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Australian
Orthodontic Journal
Volume 26 Number 1, May 2010
Contents
Original articles
1
10
16
21
27
33
38
42
49
56
61
66
73
78
84
The dimensions of the roots of the human permanent dentition as a guide to the selection of optimal orthodontic forces
Brian Lee
Amorphous calcium phosphate-containing orthodontic composites. Do they prevent demineralisation around orthodontic
brackets?
Tancan Uysal, Mihri Amasyali, Alp Erdin Koyuturk, Suat Ozcan and Deniz Sagdic
Cytotoxicity of orthodontic separating elastics
Matheus Melo Pithon, Rogério Lacerda dos Santos, Fernanda Otaviano Martins, Maria Teresa Villela Romanos and
Mônica Tirre de Souza Araújo
Porcelain brackets during initial alignment: are self-ligating cosmetic brackets more efficient?
Peter Miles and Robert Weyant
Display of the incisors as functions of age and gender
Andrea Fonseca Jardim da Motta, Margareth Maria Gomes de Souza, Ana Maria Bolognese, Clarice Júlia Guerra
and José Nelson Mucha
McNamara norms for Turkish adolescents with balanced faces and normal occlusion
Nihat Kilic, Gülhan Catal and Hüsamettin Oktay
Assessment of slot sizes in self-ligating brackets using electron microscopy
Nidhi B. Bhalla, Sarah A. Good, Fraser McDonald, Martyn Sherriff and Alex C. Cash
Space planning sensitivity and specificity: Royal London Space Planning and Korkhaus Analyses
Rania Dause, Martyn Cobourne and Fraser McDonald
Response of the expanded inter-premaxillary suture to intermittent compression. Early bone changes
Tancan Uysal, Huseyin Olmez, Mihri Amasyali, Yildirim Karslioglu, Atilla Yoldas and Omer Gunhan
Associations between upper lip activity and incisor position
Nihat Kilic
Effects of levelling of the curve of Spee on the proclination of mandibular incisors and expansion of dental arches:
a prospective clinical trial
Nikolaos Pandis, Argy Polychronopoulou, Iosif Sifakakis, Margarita Makou and Theodore Eliades
A comparison of dental changes produced by mandibular advancement splints in the management of obstructive sleep
apnoea
Hui Ching Ang and Craig Dreyer
Does ozone water affect the bond strengths of orthodontic brackets?
Matheus Melo Pithon and Rogerio Lacerda dos Santos
Incremental effects of facemask therapy associated with intermaxillary mechanics
Guilherme Thiesen, Juliana de Oliveira da Luz Fontes, Michella Dinah Zastrow and Naudy Brodbeck May
Bond strengths of different orthodontic adhesives after enamel conditioning with the same self-etching primer
Rogelio J. Scougall-Vilchis, Chrisel Zárate-Díaz, Shusuke Kusakabe and Kohji Yamamoto
Case report
90
Multidisciplinary treatment of a fractured root: a case report
Osmar Aparecido Cuoghi, Álvaro Francisco Bosco, Marcos Rogério de Mendonça, Pedro Marcelo Tondelli and
Yésselin Margot Miranda-Zamalloa
Editorial
95
Can an optimal force be estimated?
Michael Harkness
General
97
102
106
Book reviews
Research reviews
New products
107
108
Calendar
ASO Directory
Australian Orthodontic Journal Volume 26 No. 1 May 2010
The dimensions of the roots of the human
permanent dentition as a guide to the selection
of optimal orthodontic forces
Brian Lee
Bonnet Hill, Tasmania, Australia
Background: The dimensions of the roots of the teeth are important in the assessment of orthodontic anchorage and to estimate
the forces to be used during orthodontic tooth movement.
Aims: To investigate the relations between the lengths, widths and projected areas of the roots of the permanent teeth.
Methods: Intact, extracted human permanent teeth were photographed and the lengths, widths and projected areas of selected
surfaces measured. Descriptive statistics and associations between selected linear dimensions and root areas were calculated.
Results: The data showed significant kurtosis and skewness. Neither exponential nor polynomial transformations improved the
goodness of fit, and there was no a priori reason to use other than linear regression. When the lengths of all teeth were
multiplied by the respective widths of the mesial, distal and lingual surfaces, the correlations between the product of length and
width and area improved in 28 out of 30 surfaces. In the lower arch the correlation coefficients ranged from r = .343 (mesial
surface first premolar) to r = .845 (mesial surface of the canine). The correlations in the upper arch ranged from r = .201
(mesial surface of the second molar) to r = .847 (mesial surface lateral incisor).
Conclusions: For clinical purposes, root length may be an acceptable indicator of root area. Low correlations were attributed to
variations in root shape.
(Aust Orthod J 2010; 26: 1–9)
Received for publication: January 2009
Accepted: February 2010
Brian Lee: bjlee3@bigpond.com
Introduction
In 1952 Storey and Smith showed that orthodontic
forces above a certain level produced lower rates of
tooth movement than forces below that level.1
They named the lower forces ‘optimal’ forces. This
definition has been extended to include the proviso of
little or no permanent damage to the root and/or
the tissues surrounding the root. Importantly, it was
suggested that it was the pressure exerted by the
root on the surrounding tissues rather than the actual
numeric value of the force that was a critical factor in
tooth movement.1 Almost coincidentally, Begg published results of cases with dramatically short treatment times treated entirely by using round wires with
small cross-sectional areas which seemed to support
the notion of differential force, which is the use of
light and heavy forces to control the speed of tooth
movement.2
© Australian Society of Orthodontists Inc. 2010
Various authors have investigated root dimensions
such as the surface area;3–12 root volume,13,14 the
relation between root length and crown diameter14
and the projected area of the roots,15,16 that may be
important for tooth movement. It has been argued
that the relative size of the root(s) may indicate a
tooth’s resistance to an orthodontic force or the
anchorage value.17 High forces are required to move
teeth with large root surface areas. If it were possible
to determine the optimal force levels for tooth movement prior to the commencement of treatment,
appliances would function with greater efficiency.
Our attention was thus focused on the areas of the
roots of the permanent dentition.
In this study the lengths, widths and projected areas
of the roots of the upper and lower permanent teeth,
including the third molars, were measured. Our
intention was to gain an insight into the relations
Australian Orthodontic Journal Volume 26 No. 1 May 2010
1
LEE
Table I. Upper teeth, lengths and projected areas of selected surfaces.
Tooth
N
Minimum
Q25
Median
Q75
Maximum
r
R2
Distal length (cm)
1
2
3
4
5
6
7
32
32
32
30
27
31
32
1.10
1.36
1.20
1.04
0.98
0.80
0.90
1.38
1.50
1.56
1.28
1.28
1.13
1.16
1.50
1.61
1.83
1.39
1.36
1.23
1.27
1.57
1.68
1.95
1.49
1.46
1.29
1.39
1.65
1.84
2.05
1.73
1.59
1.54
1.72
.714
.762
.838
.715
.611
.524
.299
0.511
0.581
0.702
0.512
0.373
0.274
0.090
Distal area (cm2)
1
2
3
4
5
6
7
32
32
32
30
27
31
32
0.43
0.56
0.62
0.64
0.48
1.18
0.69
0.60
0.66
0.82
0.74
0.66
1.47
1.00
0.65
0.71
0.98
0.83
0.72
1.54
1.12
0.70
0.77
1.06
0.89
0.77
1.66
1.26
0.82
0.88
1.54
1.15
0.93
2.08
1.62
Lingual length (cm)
1
2
3
32
32
32
1.08
1.12
1.08
1.20
1.20
1.49
1.28
1.32
1.66
1.37
1.43
1.80
1.48
1.59
1.90
.499
.731
.746
0.249
0.535
0.557
Lingual area (cm2)
1
2
3
32
32
32
0.42
0.32
0.34
0.45
0.38
0.56
0.50
0.45
0.60
0.56
0.49
0.64
0.70
0.62
0.84
Mesial length (cm)
1
2
3
4
5
6
7
8
32
32
32
30
27
31
32
12
1.09
1.29
1.20
1.08
1.00
1.06
1.06
0.83
1.41
1.50
1.69
1.29
1.30
1.22
1.20
0.93
1.53
1.59
1.87
1.36
1.39
1.34
1.25
0.99
1.64
1.73
1.99
1.49
1.45
1.41
1.38
1.10
1.74
1.86
2.20
1.71
1.61
1.66
1.62
1.15
.803
.847
.566
.713
.558
.730
.201
.456
0.645
0.717
0.320
0.508
0.312
0.533
0.040
0.208
Mesial area (cm2)
1
2
3
4
5
6
7
8
32
32
32
30
27
31
32
12
0.50
0.54
0.61
0.48
0.48
1.10
0.84
0.77
0.59
0.65
0.97
0.73
0.70
1.56
1.14
0.97
0.67
0.69
1.00
0.85
0.74
1.68
1.23
1.19
0.74
0.74
1.09
0.94
0.79
1.81
1.31
1.27
0.85
0.86
1.83
1.13
0.96
2.34
1.75
1.36
Surface
2
Australian Orthodontic Journal Volume 26 No. 1 May 2010
ROOT DIMENSIONS AS A GUIDE TO 0PTIMAL ORTHODONTIC FORCES
Table II. Lower teeth, lengths and projected areas of selected surfaces.
Tooth
N
Minimum
Q25
Median
Q75
Maximum
r
R2
Distal length
1
2
3
4
5
6
7
30
25
26
39
23
27
27
1.16
1.20
1.44
1.16
1.21
0.86
1.00
1.31
1.34
1.61
1.44
1.42
1.19
1.12
1.39
1.48
1.74
1.50
1.60
1.26
1.20
1.47
1.57
1.79
1.60
1.64
1.39
1.37
1.68
1.73
2.17
2.00
1.79
1.70
1.60
.441
.518
.835
.375
.485
.608
.820
0.195
0.269
0.696
0.141
0.236
0.37
0.672
Distal area
1
2
3
4
5
6
7
30
25
26
39
23
27
27
0.46
0.48
0.64
0.67
0.64
0.98
0.71
0.53
0.58
0.80
0.85
0.70
1.30
1.10
0.57
0.62
0.97
1.02
0.76
1.40
1.30
0.61
0.68
1.12
1.20
0.80
1.50
1.50
0.76
0.84
1.51
1.53
0.95
2.24
1.71
Lingual length
1
2
3
33
47
28
1.02
1.10
1.36
1.18
1.32
1.61
1.28
1.40
1.67
1.37
1.48
1.77
1.65
1.60
2.01
.529
.665
.717
0.277
0.442
0.514
Lingual area
1
2
3
33
47
28
0.22
0.26
0.49
0.27
0.31
0.61
0.29
0.34
0.64
0.38
0.37
0.74
0.48
0.51
0.93
Mesial length
1
2
3
4
5
6
7
8
33
19
22
39
23
27
27
12
1.31
1.20
1.40
1.16
1.17
1.16
1.02
1.03
1.34
1.45
1.68
1.41
1.45
1.26
1.08
1.28
1.42
1.57
1.78
1.48
1.58
1.40
1.30
1.35
1.51
1.60
1.94
1.56
1.60
1.48
1.41
1.39
1.75
1.78
2.30
2.04
1.84
1.78
1.55
1.73
.566
.594
.845
.343
.582
.807
.812
.554
0.321
0.353
0.714
0.118
0.338
0.651
0.661
0.307
Mesial area
1
2
3
4
5
6
7
8
33
19
22
39
23
27
27
12
0.53
0.54
0.64
0.66
0.48
1.11
0.87
0.65
0.57
0.60
0.80
0.82
0.70
1.32
1.11
0.70
0.63
0.64
0.96
1.02
0.80
1.46
1.38
0.83
0.67
0.70
1.11
1.15
0.83
1.55
1.50
1.03
0.88
0.92
1.57
1.53
1.06
2.33
1.88
1.50
Surface
Australian Orthodontic Journal Volume 26 No. 1 May 2010
3
LEE
between the lengths and widths to the areas of
corresponding root surfaces in the hope that this
information may be of value to clinicians planning
orthodontic anchorage and selecting appropriate
forces for tooth movement.
Materials and methods
Measurements were made of the root surfaces of
approximately 580 extracted human permanent
teeth, including the third molars. Intact and fully
formed permanent teeth were collected in the period
1963–65 and measured using the methods described
below. The age, gender and ethnicity of the subjects
were not recorded.
The teeth were cleaned of attached soft tissue, dried,
labelled and numbered. Multi-rooted teeth were sectioned through the furcation(s) in order to obtain a
clear view of the root surfaces and each root was photographed and measured separately. The four surfaces
of the teeth (mesial, distal, buccal, lingual) were
photographed alongside a metric rule. The film plane
was parallel to the long axis of each tooth. The photographic images were enlarged x10 and the outline of
each root surface traced on paper. The lengths and
widths of the roots were measured on the tracings.
The length of the proximal surface of a root was the
distance from the root apex to the peak of the curve
of the cemento-enamel junction on the proximal surface, and the length of a lingual surface was the
distance from the apex to the lowest point on the
curve of the cemento-enamel junction. Root width
was measured at the cemento-enamel junction.
The dimensions of the same surfaces were added.
Data for corresponding right and left teeth were
combined.
The area of each root surface was then measured
directly with a planimeter (Allbrit 37595 Fixed Arm
planimeter, Stanley, London, UK). The accuracy of
the planimeter was tested before use by tracing a
circle using the radius arm provided with the instrument to determine if the area of the traced circle
coincided with the nominated area. Before analysis,
the planimeter measurements were converted to the
actual sizes by dividing the linear measurements by
10 and the area measurements by 100. All linear and
width measurements are in centimetres (cm) and the
areas in centimetres squared (cm2).
Descriptive statistics and skewness and kurtosis were
calculated for the distal, mesial and lingual lengths,
4
Australian Orthodontic Journal Volume 26 No. 1 May 2010
widths and projected areas of the upper and lower
teeth. Pearson’s correlation coefficients and regression
equations between the lengths and projected areas of
corresponding root surfaces, and associations between
root length and the calculated area (the product of
length and width) to the projected area of corresponding surfaces were also calculated for teeth with width
and length measurements.
Results
The results are given in Tables I and II and Figures 1
and 2. The tables contain the sample sizes, minimum
and maximum values, quartile values, medians, correlations of length to the projected areas of selected permanent teeth and coefficients of determination (R2
values). The measured and calculated values of the
various surfaces of selected upper and lower teeth are
shown in Figure 1. Regression lines of the relations
between projected root length and area of the distal,
mesial and lingual surfaces of the upper and lower
teeth are given in Figure 2.
The median length of the distal surface of the upper
central incisor root was 1.50 cm and for the upper
canine it was 1.83 cm (Table I). The median areas of
the distal surfaces of the upper canine and first molar
were 0.98 and 1.54 cm2, respectively. The palatal surface of the upper lateral incisor (Median: 1.32 cm)
was slightly longer than that of the upper central incisor (Median: 1.28 cm), but shorter than the upper
canine (Median length: 1.66 cm). The median areas
of the palatal surfaces of the upper central incisor,
upper lateral incisor and upper canine were 0.50,
0.45 and 0.60 cm2, respectively. Although the mesial
surface of the upper first molar was shorter than all
other teeth in the upper arch except the second and
third molars, it had the largest mesial area (Median:
1.68 cm2). The mesial areas (medians) of all upper
teeth were larger than the distal areas (medians) of
corresponding teeth, except for the lateral incisors.
The canine was the longest tooth in the lower arch,
but the areas of the mesial and distal root surfaces
(Distal surface area median: 0.97 cm2; Mesial surface
area median: 0.96 cm2) were less than the corresponding areas (Distal area median: 1.40 cm2; Mesial
area median: 1.46 cm2) of the first molar (Table II).
The distal surface of the lower first premolar was
shorter than the same surface of the canine, but the
median area of the distal surface of the first premolar
was greater than the median area of the canine.
ROOT DIMENSIONS AS A GUIDE TO 0PTIMAL ORTHODONTIC FORCES
1.6
Length
2
Width
1.5
Calculated
1
0.5
Length/Width/Calculated area
(cm/cm/cm2)
Length/Width/Calculated area
(cm/cm/cm2)
2.5
Length
1.4
1.2
1
0.8
0.6
0.4
0.2
0
0
0
0.5
1
1.5
Measured area cm2
2
2.5
0
Length: y = 1.1851x + 0.6068 R2 = 0.7022
Width: y = 0.1838x + 0.6022 R2 = 0.3644
Calculated area: y = 1.273x + 0.1395 R2 = 0.8378
0.1
0.2
0.3
0.4
0.5
0.6
Calculated area cm2
0.7
0.8
Length: y = 0.7647x + 0.8948 R2 = 0.2495
(b) Upper central incisor lingual.
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Length
2.5
Length/Width/Calculated area
(cm/cm/cm2)
Length/Width/Calculated area
(cm/cm/cm2)
(a) Upper canine distal.
Length
Width
Calculated
2
1.5
1
0.5
0
0
0.1
0.2
0.3
0.4
0.5
Measureed area cm2
0.6
0.7
0
Length: y = 1.2694x + 0.7516 R2 = 0.5349
0.5
1
1.5
Measured area cm2
2
2.5
Length: y = 0.7085x + 0.8334 R2 = 0.3119
Width: y = 0.9536x + 0.369 R2 = 0.6159
Calculated area: y = 0.3104x + 0.5616 R2 = 0.3256
(c) Upper lateral incisor lingual.
(d) Upper second premolar mesial.
Length
Width
Calculated
2
1.5
1
0.5
0
2.5
Length/Width/Calculated area
(cm/cm/cm2)
Length/Width/Calculated area
(cm/cm/cm2)
2.5
Length
Width
Calculated
2
1.5
1
0.5
0
0
0.5
1
1.5
Measured area cm2
2
2.5
0
0.2
0.4
0.6
0.8
1
Measured area cm2
1.2
Length: y = 0.5239x + 0.465 R2 = 0.533
Width: y = 0.2651x + 0.6938 R2 = 0.3841
Calculated: y = 0.9501x + 0.0614 R2 = 0.7864
Length: y = 0.6499x + 1.1004 R2 = 0.6968
Width: y = 0.2969x + 0.4695 R2 = 0.6301
Calculated: y = 1.0502x + 0.3006 R2 = 0.7814
(e) Upper first molar mesial.
(f) Lower canine distal.
1.4
1.6
Figure 1. Plots derived from raw data. Individual data are indicated and regression lines for length, width and calculated area (length x width) with the projected
(measured) area are given.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
5
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Length
0
0.2
0.4
0.6
0.8
Measured area
1
1.2
Length: y = 0.657x + 1.0277 R2 = 0.3383
(g) Lower second premolar mesial.
Length/Width/Calculated area
(cm/cm/cm2)
Length/Width/Calculated area
(cm/cm/cm2)
LEE
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Length
Width
Calculated
0
0.5
1
1.5
Measured area cm2
2
2.5
Length: y = 0.52181x + 0.6131 R2 = 0.6509
Width: y = 0.1664x + 0.6087 R2 = 0.3484
Calculated: y = 0.7048x + 0.1559 R2 = 0.6835
(h) Lower first molar mesial.
Figure 1 (Continued). Plots derived from raw data. Individual data are indicated and regression lines for length, width and calculated area (length x width) with the
projected area are given.
In the upper arch, the coefficients range from .847
between the length and area of the mesial surface of
the lateral incisor to .201 between the length and area
of the mesial surface of the second molar. The correlation coefficient between the distal surface and distal
area of the upper canine was .838 and between the
length and area of the mesial facing root surfaces of
the upper first molar it was .730. In the lower arch,
the coefficients for the distal surface of the canine and
the mesial surface of the first molar were .835 and
.807, respectively.
There was significant kurtosis and skewness in the
data (more than two standard deviations) indicating
that the distributions were not normal, but there was
no apparent relationship between skewness and the
coefficients of determination, nor was there any consistency in the sense or direction of the skew.
However, neither exponential nor polynomial transformations improved the goodness of fit, and there is
no a priori reason to use other than linear regression.
Coefficients of determination (R2) for selected teeth
are given in Tables I and II. The coefficient of determination indicates the degree to which the variation
amongst projected areas can be accounted for by root
length.
When the lengths of the upper teeth were multiplied
by the respective widths the correlations with the corresponding root surface lengths increased in 28 of 30
surfaces. Only the correlations between the lengths
and calculated areas of the distal surfaces of the upper
first and second molars, and the mesial lengths and
calculated areas of the lower lateral incisor and distal
surface of the lower central incisor did not improve.
6
Australian Orthodontic Journal Volume 26 No. 1 May 2010
Discussion
This study set out to determine if clinically useful
associations existed between the lengths and areas of
the roots of the upper and lower teeth, however later
in the study, root width was included to determine
whether that dimension was of any value in estimating projected area. A strong association (>.8) would
enable a clinician to use the product of root length
and width as a predictor of root area and select an
appropriate force to obtain optimal tooth movement
and/or estimate the anchorage value of a tooth or
group of teeth.
The coefficients for the distal surfaces of the upper
canines and the mesial surfaces of the lower first
molars accounted for approximately 70 and 65 per
cent of the variations in root area, respectively, when
the root lengths were known. The coefficients of
determination were relatively high for several other
teeth, notably the mesial surfaces of the upper lateral
incisor and the lower first and second molars. The
coefficient of determination for the lingual surface of
the upper central incisor was only .249, possibly
because an incisor with a short, wide root can have
the same area as one with a long, slender root. For the
upper central incisor, root length alone is not a good
predictor of root area. We succeeded in improving the
predictability of root length by using a calculated area
(length x width) in our calculations. Data for these
calculations are available on the Journal website. In
all but two cases, this quantity accounted for more
variance than using length alone.
Estimation of optimal forces needs to take into
account teeth with unusual variations in the axes of
ROOT DIMENSIONS AS A GUIDE TO 0PTIMAL ORTHODONTIC FORCES
Upper 1
Upper 2
Upper 3
Upper 4
Upper 5
Upper 6
Upper 7
Distal area (cm2)
2
1.5
1
2.5
0.5
Upper 2
Upper 3
1.5
1
0.5
0
0
0.5
1
1.5
Distal length (cm)
2
2.5
0
(a) Regression lines showing the relations between distal lengths and areas
for the upper teeth.
2.5
Upper 1
Upper 2
Upper 3
Upper 4
Upper 5
Upper 6
Upper 7
Upper 8
2
1.5
1
0.5
1
L:ingual length (cm)
1.5
2
(b) Lingual lengths and areas for the upper teeth.
2.5
Lower 1
Lower 2
Lower 3
Lower 4
Lower 5
Lower 6
Lower 7
2
Distal area (cm2)
0
Mesial area (cm2)
Upper 1
2
Lingual area (cm2)
2.5
0.5
1.5
1
0.5
0
0
0
0.5
1
1.5
Mesial length (cm)
2
2.5
0
(c) Mesial lengths and areas for the upper teeth.
0.5
1
1.5
Distal length (cm)
2
2.5
(d) Distal lengths and areas for the lower teeth.
2.5
2.5
Lower 1
Lower 2
Lower 3
Lower 4
Lower 5
Lower 6
Lower 7
Lower 8
Lower 1
2
Lower 2
Lower 3
1.5
1
0.5
Mesial area (cm2)
Lingual area (cm2)
2
1.5
1
0.5
0
0
0
0.5
1
1.5
Lingual length (cm)
2
2.5
(e) Lingual lengths and areas for the lower teeth.
0
0.5
1
1.5
Mesial length (cm)
2
2.5
(f) Mesial lengths and areas for the lower teeth.
Figure 2. Regression lines for the length and areas of the upper and lower teeth.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
7
LEE
Figure 3. Caliper designed to measure tooth dimensions at the
cemento-enamel junction.
the crowns and roots and/or root bends or curves.18,19
Also the shape of the cemento-enamel junction on a
proximal surface varies according to the labio-lingual
width of the root.18 In a wide tooth the curve of the
cemento-enamel junction has a somewhat flattened
shape, whereas in a narrow tooth the junction is
somewhat angular in shape.
Limitations in this study that should be considered
are our methods of measuring length and area: both
measurements were made parallel to the long axis of
the root and were influenced to a certain degree
by the angle between the root surface and the long
axis of the tooth, and the shape of the root.
Some teeth had pyramidal roots and other teeth had
curved roots. These variations, although small, may
contribute to the variability in tooth movement
encountered by a clinician using root length to
estimate root area and an optimal force. For some
teeth the projected length, for example of the upper
lateral incisor, would be less than the actual length.
When, however, the width (at right angles to the root
surface of interest) and the projected length of a root
are known, the actual length of the root can be calculated. Bucco-lingual widths are difficult to
measure using traditional radiographs. To overcome
this, we designed a caliper to measure the width at
the cemento-enamel junction and have used this
instrument to estimate projected areas and have
obtained results consistent with other workers
(Figure 3).16,20,21 Finally, the strengths of this study
are the size of the samples and our use of teeth with
fully developed roots.
How can the results be applied to estimate the
optimum force for tooth movement or anchorage? To
8
Australian Orthodontic Journal Volume 26 No. 1 May 2010
use the graphs, first decide on a treatment plan and
the directions of tooth movement. Estimate the root
length of a particular tooth from a radiograph or
from an already extracted tooth and use the appropriate regression line to obtain an estimate of root
area. As the mean peak velocity of movement of the
canines in both humans and dogs occurred when a
mean pressure of 200 cN/cm-2 was exerted, multiply
this estimated area by 200 (as force equals pressure x
area) to determine the force required.20 When this
figure is applied to the median projected area of the
distal surface of the upper canine (0.98 cm2) the
mean optimum pressure is 196 cN/cm-2. This
approximates reported estimates of 197 cN/cm-2
based on experimental data from humans.1,16,21,22
Using this approach it is now possible to estimate the
forces required to obtain optimal rates of tooth movement and, by using higher forces, a stable anchor
unit. Eventually, other root dimensions, such as
volume and bone density may improve estimates of a
tooth’s resistance to orthodontic movement than either
root length or the product of root length and width.12,13
Conclusions
The following conclusions were drawn:
1. For clinical purposes, root length may be an
acceptable indicator of root area.
2. The product of root length and width resulted in
higher coefficients of determination. A method of
measuring bucco-lingual width is described.
2. Low correlations between root length and area
were attributed to variations in root shape.
Acknowledgments
I would like to thank Professor Shen Gang for his
assistance in collating the data for this study and
Desmond Fitzgerald and Geoffrey Fenn for their
assistance with the statistics and my wife Joanna for
help with the preparation of this report.
Corresponding author
Dr Brian W. Lee
3 Lynden Road
Bonnet Hill, Tasmania 7053
Australia
Tel: (+61 3) 6229 9468
Email: bjlee3@bigpond.com
ROOT DIMENSIONS AS A GUIDE TO 0PTIMAL ORTHODONTIC FORCES
References
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
Storey E, Smith R. Force in orthodontics and its relation to
tooth movement. Aust J Dent 1952;56:11–18.
Begg PR. Stone age man’s dentition. Am J Orthod 1954;40:
517–31.
Brown R. A method of measurement of root area. J Can
Dent Assoc 1950;16:130–2.
Jepsen A. Root surface measurement and a method for x-ray
determination of root surface area. Acta Odontol Scand
1963:21:35–46.
Hillam DG. Stresses in the periodontal ligament. J
Periodont Res 1973; 8:51–6.
Nicholls JI, Daly CH, Kydd WL. Root surface measurement
using a digital computer. J Dent Res 1974;53:1338–41.
Jarabak JR, Fizzell JA. Techniques and treatment with the
light wire appliances: light differential force in clinical
orthodontics. Mosby, St Louis 1963:192–3,353–79.
Herman DW, Gher ME Jr, Dunlap RM, Pelleu GB Jr. The
potential attachment area of the maxillary first molar. J
Periodontol 1983;54:431–4.
Anderson RW, McGarrah HE, Lamb RD, Eick JD. Root
surface measurements of mandibular molars using stereophotogrammetry. J Am Dent Assoc 1983:107:613–15.
Dunlap RM, Gher ME Jr. Root surface measurements of the
mandibular first molar. J Periodontol 1985;56:234–8.
Verdonshot EH, Sanders AJ, Plasschaert AJ. Computeraided image analysis system for area measurement of tooth
root surfaces. J Periodontol 1990; 61:275–80.
Mowry JK, Ching MG, Orjansen MD, Cobb CM, Friesen
LR, MacNeill SR et al. Root surface area of the mandibular
cuspid and bicuspids. J Periodontol 2002;68:1095–100.
Bjorndal AM, Henderson WG, Skidmore AE, Kellner FH.
Anatomic measurements of human teeth extracted from
males between the ages of 17 and 21 years. Oral Surg 1974;
38:791–803.
14. Kay S, Forscher BK, Sackettt LM, Tooth root length-volume
relationships, an aid to periodontal prognosis. 1. Anterior
teeth. Oral Surg Oral Med Oral Pathol 1954:7:735–40.
15. Garn SM, Van Alstine WL Jr, Cole PE. Relationship
between root lengths and crown diameters of corresponding
teeth. J Dent Res 1978;57:636.
16. Lee BW. The force requirements for tooth movement. Part
III: The pressure hypothesis tested. Aust Orthod J 1996;14:
93–7.
17. Chen SK, Pan JH, C CM, Jeng JY. Accuracy of supported
root ratio estimation from projected length and area using
digital radiographs. J Periodontol 2004;75:866–71.
18. Taylor RMS. Variation in form of human teeth: I. An
anthropologic and forensic study of maxillary incisors. J
Dent Res 1969; 48:5–16.
19. Taylor RMS. Variation in form of human teeth: I. An
anthropologic and forensic study of maxillary canines. J
Dent Res 1969; 48:173–82.
20. Ren Y, Maltha J, Van’t Hof MA, Kuijpers-Jagtman AM.
Optimum force magnitude for orthodontic tooth movement: a systematic literature review. Am J Orthod
Dentofacial Orthop 2004;125:71–7.
21. Lee BW. The force requirements for tooth movement. Part I:
Tipping and bodily movement. Aust Orthod J 1995;13:
238–48.
22. Smith R, Storey E. The importance of force in orthodontics.
Design of cuspid retraction springs. Aust J Dent 1952;56:
291–304.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
9
Amorphous calcium phosphate-containing
orthodontic composites. Do they prevent
demineralisation around orthodontic brackets?
Tancan Uysal, * Mihri Amasyali, † Alp Erdin Koyuturk, + Suat Ozcan, ±
and Deniz Sagdic †
Department of Orthodontics, Erciyes University, Kayseri, Turkey and King Saud University, Riyadh, Saudi Arabia,* Department of
Orthodontics, Gülhane Military Medical Academy, Ankara, Turkey,† Department of Pediatric Dentistry, Ondokuz Mayis University, Samsun,
Turkey,+ and the Department of Conservative Dentistry and Endodontics, Gazi University, Ankara, Turkey±
Background: A preliminary study using laser fluorescence suggested that amorphous phosphate-containing orthodontic
composites may prevent demineralisation around bonded orthodontic brackets.
Objective: To compare the microhardness of the enamel around brackets bonded with an amorphous calcium phosphatecontaining orthodontic composite (ACP-containing) with the microhardness of the enamel around brackets bonded with a
conventional composite resin.
Methods: Forty extracted upper premolars were used. Orthodontic brackets were bonded to the teeth with either an ACPcontaining composite resin (N = 20) or a conventional composite resin (N = 20). The latter were used as the control. The
crowns of all teeth were painted with an acid resistant varnish, leaving a 2 mm ring of exposed enamel around the brackets.
The teeth were then subjected to a daily cycle of demineralisation for 6 hours and remineralisation for 18 hours for 21 days.
Each tooth was sectioned and the microhardness of the enamel determined 25, 50, 75, 100 and 150 µm from the surface.
Results: The enamel was significantly harder 25 µm (p = 0.000) and 50 µm (p = 0.001) from the enamel surface in the teeth
with brackets bonded with the ACP-containing composite resin as compared with the control teeth.
Conclusion: ACP-containing orthodontic composite resins may reduce the enamel decalcification found in patients with poor
oral hygiene.
(Aust Orthod J 2010; 26: 10–15)
Received for publication: April 2009
Accepted: July 2009
Tancan Uysal: tancanuysal@yahoo.com
Mihri Amasyali: mamasyali@yahoo.com.tr
Alp Koyuturk: alperdinkoyuturk@hotmail.com
Suat Ozcan: suatozcan@gazi.edu.tr
Deniz Sagdic: dsagdic@hotmail.com
Introduction
Poor oral hygiene following placement of a bonded
orthodontic appliance can result in unsightly white
spot lesions on the labial surfaces of the anterior
teeth.1,2 Although a white spot lesion is the first visible sign of enamel softening, measurable demineralisation can occur around orthodontic brackets as early
as one month after an appliance has been placed.3–6
Overall management of white spot lesions involves
methods of both preventing demineralisation and
encouraging remineralisation of existing lesions.7 The
10
Australian Orthodontic Journal Volume 26 No. 1 May 2010
former includes good oral hygiene and the latter may
include the application of materials, such as casein
phosphopeptide – amorphous calcium phosphate
nano-complexes (CPP-ACP) that enhance remineralisation of enamel.8 A recent development has been
the addition of amorphous calcium phosphate (ACP)
to orthodontic composites with the intention of
enhancing enamel remineralisation around bonded
brackets. This area is particularly prone to demineralisation because plaque readily accumulates on
orthodontic composites.
© Australian Society of Orthodontists Inc. 2010
DO ACP-CONTAINING COMPOSITE RESINS PREVENT DEMINERALISATION?
In a preliminary study we used a laser fluorescence
device to compare ‘enamel demineralisation’ around
orthodontic brackets bonded with either an ACPcontaining composite or a resin-modified glass
ionomer cement.9 We found that ACP-containing
orthodontic composites provided the highest reductions in enamel demineralisation when compared
with a resin-modified glass ionomer cement and the
control. However, Diniz et al. recently reported that
laser fluorescence devices for detecting in-vitro
demineralisation are unreliable.10 Thus, we decided
to determine the extent of demineralisation around
orthodontic brackets bonded with either an ACPcontaining composite resin or a conventional
composite resin by measuring enamel microhardness:
one of the traditional methods of determining early
demineralisation.4–6,10 The method, which has been
widely used in caries research, correlates demineralisation with microhardness.4
The aim of this in-vitro study was to compare the
microhardness of the enamel around brackets bonded
with an amorphous calcium phosphate-containing
orthodontic composite (ACP-containing) with the
enamel around brackets bonded with a conventional
composite resin after the teeth had been exposed to
acid attack.
Materials and methods
Preparation of the teeth
Forty caries-free human upper premolars, extracted
for orthodontic reasons, were used in this study.
Before use the teeth were stored in 0.1 per cent
thymol for periods no longer than one month. Teeth
with hypoplastic areas, cracks and/or gross irregularities of enamel structure or treated with chemical
agents such as alcohol, formalin or hydrogen peroxide were excluded from the study. Soft tissue remnants and calculus were removed from the teeth and
the crowns cleaned with fluoride-free pumice and a
rubber cup. The teeth were then stored in Streck
Tissue Fixative (Streck Laboratories, Inc., Omaha,
NE, USA) for two weeks. This solution has an
antimicrobial action and does not compromise histological examination of the enamel following artificial
demineralisation.11 The teeth were randomly distributed into the control (Group 1) and the experimental
group (Group 2) equally. The buccal surface of each
premolar was etched with 37 per cent orthophosphoric acid gel (3M Dental Products, St. Paul,
MN, USA) for 15 seconds, rinsed with water for 15
seconds and dried with oil-free air for 10 seconds
until the enamel appeared frosty-white.
In Group 1, Transbond XT primer (3M Unitek,
Monrovia, CA, USA) was applied to the etched surface in a thin film and not cured. Transbond XT composite paste was applied to the base of the stainless
steel bracket (Dyna-Lok series, 100-gauge mesh, 3M
Unitek, USA). Each bracket was positioned at the
maximum contour mesio-distally in the middle one
third of the buccal surface occluso-gingivally and
parallel to the long axis of the tooth, and pressed
firmly into place. The excess composite was removed
with a scaler.
In Group 2, a thin layer of ACP-containing orthodontic composite (Aegis Ortho, Harry J Bosworth
Co., IL, USA) was applied to the etched enamel and
the base of the bracket. The bracket was pressed onto
the buccal surface of the tooth in an identical position
to that used in Group 1. Following the manufacturer’s recommendations, excess composite was not
removed.
A light-emitting diode curing unit (Elipar Freelight 2,
3M-ESPE, St. Paul, MN, USA) was applied to the
mesial and distal edges of the brackets in both groups
for 10 seconds per side (Total time: 20 seconds).
Following curing, the crowns of the teeth were painted with an acid-resistant varnish, leaving a 2 mm ring
of exposed enamel around the brackets. The specimens were stored in 100 per cent humidity for 12
hours at 37 °C.
Demineralisation procedure
The baseline mineralisation of the enamel around
each bracket was measured with a portable batterypowered laser fluorescence device (Diagnodent Pen,
KaVo, Germany). The scores in both groups
were under 13, indicating that the enamel was not
demineralised and all teeth had the same risk of caries
(Figure 1).
The demineralisation procedure was adapted from
the method described by Hu and Featherstone.12 The
daily procedure of pH cycling included a demineralisation period of 6 hours (0900–1500 hours) and a
remineralisation period of 18 hours (1500–0900
hours). The crown of each tooth was immersed in 60
mL of demineralisation solution containing 2.0
mmol/L calcium, 2.0 mmol/L phosphates, and 75
Australian Orthodontic Journal Volume 26 No. 1 May 2010
11
UYSAL ET AL
Table I. Intra- and inter-examiner agreement for the microhardness
scores.
Observation
Intra-examiner agreement (Examiner 1)
Intra-examiner agreement (Examiner 2)
Inter-observer agreement
Kappa score (K)
0.83
0.88
0.81
Cohen's Kappa:
K < 0.40 poor agreement
K = 0.41 - 0.60 moderate agreement
K = 0.61 - 0.80 substantial agreement
K > 0.80 - almost perfect agreement
Figure 1. Measurement of the demineralisation on the occlusal side of the
bracket by Diagnodent Pen.
mmol/L acetate at pH 4.3 for 6 hours at 37 °C.
Specimens were then removed from the demineralisation solution, rinsed with deionised water and
immersed in 40 mL of the remineralisation solution
at 37 °C overnight (18 hours), to simulate the remineralising stage of the caries process. The remineralisation solution consisted of 1.5 mmol/L calcium, 0.9
mmol/L phosphates, 150 mmol/L potassium chloride, and 20 mmol/L cacodylate buffers at pH 7.0.
This cycling procedure was repeated daily for 21 days.
On day 21, the presence of demineralised enamel was
confirmed with the laser fluorescent device and, visually, the enamel appeared frosty-white when the teeth
were dried. The teeth were removed from the solution
and the brackets removed.
Microhardness analysis
The roots of the teeth were removed with a watercooled diamond disk. The crowns were hemisectioned vertically into mesial and distal halves with
a large 15 HC wafering blade in an Isomet low-speed
saw (Buehler, Lake Bluff, IL, USA). The hemisections were cut into a cervical portion and an
occlusal portion. Both portions were embedded in
self-curing epoxy resin (Epo-Kwick, Buehler, Lake
12
Australian Orthodontic Journal Volume 26 No. 1 May 2010
Bluff, IL, USA), leaving the cut face exposed. The
half crown sections were polished with abrasive paper
discs (320, 600, and 1200 grit) and polished with a
1 µm diamond spray and a cloth polishing disc
(Buehler, Lake Bluff, IL, USA). A microhardness
tester (HMV-700, Shimadzu, Kyoto, Japan) under a
2N load for 15 seconds was used for the microhardness analysis. In the occlusal and cervical regions,
indentations were made at the edge (0 µm) of the
composite and 25, 50, 75, 100, 125, and 150 µm
from the external surface of the enamel.
Statistical analysis
Data analysis was performed by using Statistical
Package for Social Sciences, (SPSS, Vers.13.0, SPSS
Inc. Chicago, IL, USA) and Excel 2000 (Microsoft
Corporation, Redmond, WA, USA). Descriptive
statistics were calculated for both groups. The
Shapiro-Wilks normality test and Levene’s variance
homogeneity test were applied to the microhardness
data. The data were normally distributed and there
was homogeneity of variances between the groups.
Occlusal and cervical microhardness scores at the
same depths in matching half crown specimens were
compared with the paired t-test. Student’s t-test was
used to compare the effect of the materials
(Transbond XT and Aegis Ortho) 25, 50, 75, 100,
125, and 150 µm from the enamel surface. For
multiple comparisons, the analysis of variance
(ANOVA) and Tukey Honestly Significant Difference (HSD) post-hoc test were used. A significance
level of p < 0.05 was used for all tests.
To determine the intra- and inter-observer agreement, the microhardness of the enamel was measured
by two investigators using the same instrument at two
separate times, and Cohen’s Kappa scores were
determined.
DO ACP-CONTAINING COMPOSITE RESINS PREVENT DEMINERALISATION?
Table II. Comparisons of enamel microhardness.
Microhardness (VHN)
Depth
Composite
N
Mean
SD
SEM
Minimum
Maximum
p
25µm
Transbond XT
Aegis Ortho
20
20
185.80
223.35
9.95
11.03
2.22
2.47
160
201
209
245
0.000
50µm
Transbond XT
Aegis Ortho
20
20
234.70
251.15
14.77
13.44
3.30
3.01
211
231
256
273
0.001
75µm
Transbond XT
Aegis Ortho
20
20
253.70
256.70
5.26
6.18
1.18
1.38
247
239
265
263
0.107
100µm
Transbond XT
Aegis Ortho
20
20
271.35
272.45
8.20
7.18
1.83
1.61
261
261
288
286
0.654
125µm
Transbond XT
Aegis Ortho
20
20
295.95
295.65
13.11
13.36
2.93
2.99
275
276
322
319
0.943
150µm
Transbond XT
Aegis Ortho
20
20
300.50
302.85
5.23
3.99
1.17
0.89
293
294
310
310
0.118
Significant values in bold
Results
The intra- and inter-examiner Kappa scores for
assessment of microhardness exceeded 0.80 (Table I).
There were no statistically significant differences
between the enamel microhardnesses in the occlusal
and cervical sections in each group (p > 0.05). The
mean microhardness scores in the Transbond XT
group (Group 1) increased steadily from 185.80
Vickers Hardness Number (VHN) at the 25 µm,
234.70 VHN at 50 µm, 253.70 VHN at 75 µm,
271.35 VHN at 100 µm, 295.95 VHN at 125 µm to
300.50 VHN at 150 µm (Table II). The mean microhardness scores in the Aegis Ortho group (Group 2)
also increased steadily from 223.35 VHN at 25 µm to
302.85 VHN at 150 µm. Although the mean differences between the two groups fell from 37.55 VHN
at 25 µm to 2.35 VHN at 150 µm, only the microhardness values at the 25 and 50 µm levels were significantly different. The enamel was significantly
harder in Group 2 (Aegis Ortho) than in Group 1
(Transbond XT) 25 and 50 µm from the enamel surface. There were no significant group differences in
enamel microhardness from 75 to 150 µm from the
enamel surface.
The microhardness scores in both groups at the 25
and 50 µm were approximately twice as variable as
the microhardness scores at the 75, 100 and 150 µm
levels, but not at the 125 µm level. For example, the
range in enamel microhardness 25 µm from the
surface was 49 VHN in the Transbond XT group
(Range: 160–209 VHN) and 44 VHN in the Aegis
Ortho group (Range: 201–245 VHN). Similar variation in the ranges occurred at the 50 µm level.
Discussion
We subjected teeth with stainless steel orthodontic
brackets bonded with either an ACP-containing composite resin or a conventional composite resin to
cycles of demineralisation and remineralisation and
measured the microhardness of the enamel surrounding the brackets. The enamel was significantly harder
25 µm and 50 µm from the enamel surface in the
teeth with brackets bonded with the ACP-containing
composite resin, suggesting that ACP-containing
composite resins may lessen the risk of demineralisation in patients with poor oral hygiene.
In this in-vitro study we attempted to simulate the
processes of acid attack that occurs beneath plaque in
vivo and subsequent remineralisation by minerals in
the saliva over 21 days.12,13 Whereas Hu and
Featherstone12 cycled the teeth in their study
through demineralisation and remineralisation solutions for 14 days, we extended our study to 21 days
because we found no visual evidence of demineralisation after 14 days exposure to the solutions. By 21
days, however, the enamel surrounding the brackets
in the control group appeared frosty-white when
dried.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
13
UYSAL ET AL
We assessed mineral loss from the teeth by determining the microhardness of the enamel at
selected depths. This is a proven and widely-used
method to determine the loss of mineral that is a
feature of early carious lesions. A strong correlation
(r = .91) was reported by Featherstone and coworkers between enamel microhardness scores and
the percentage loss of mineral in the carious lesions.13
While others have reported that the demineralisation of the enamel around orthodontic brackets
can extend as far as 75 µm below the enamel surface, Gorton and Featherstone4 and Pascotto et al.5
reported that enamel demineralisation extended
to only 30 µm from the enamel surface in vivo.
They allowed their subjects to brush their teeth
which presumably removed some/all of the
plaque and micro-organisms responsible for demineralisation.
We used a portable battery-powered laser fluorescence device to determine the levels of mineralisation
at the start of the study and after 21 days. Although
the device confirmed that the groups had similar
baseline levels of mineralisation at the start of the
study and that they were demineralised after 21 days
exposure to the solutions, these results should be
regarded with caution as it has recently been reported
that this method of determining the level of
mineralisation is unreliable.10
Bioactive materials, such as ACP or CPP-ACP have
been added to several materials used in dentistry to
increase the concentrations of calcium and phosphate
ions in dental plaque and replace minerals lost from
the enamel during the demineralisation process.14–17
CPP-ACP has been added to various products, such
as sugar-free chewing gum, mints, topical gels,
mousse, tooth paste, sports drinks and glass ionomer
cements and remineralisation of already demineralised enamel lesions has been reported.8,12,18 These
innovations are ideal for the prevention of enamel
demineralisation in vivo as the material is in close
proximity to the enamel, and there appears to be an
inverse relationship between calcium and phosphate
levels in dental plaque and caries experience.17
Sodium fluoride either alone or in combination with
CPP-ACP will also prevent enamel demineralisation
adjacent to orthodontic brackets.7 The consensus is
that ACP-containing materials have higher remineralising potential than the conventional composite
resins and cements.8,16
14
Australian Orthodontic Journal Volume 26 No. 1 May 2010
Conclusion
ACP-containing orthodontic composite resins may
reduce the enamel decalcification found in patients
with poor oral hygiene.
Acknowledgments
The authors thank Ertan Seçkin of Guney Dental for
providing the Diagnodent Pen and for supporting
this project.
Corresponding author
Dr Tancan Uysal
Erciyes Üniversitesi
Diş Hekimliği Facültesi
Ortodonti Anabilum Dall, 38039
Melikgazi
Kayseri
Turkey
Email: tancanuysal@yahoo.com
References
1.
Smales RJ. Plaque growth on dental restorative materials. J
Dent 1981;9:133–40.
2. Vorhies AB, Donly KJ, Staley RN, Wefel JS. Enamel demineralization adjacent to orthodontic brackets bonded with
hybrid glass ionomer cements: an in vitro study. Am J
Orthod Dentofacial Orthop 1998;114:668–74.
3. O’Reilly MM, Featherstone JD. Demineralization and remineralization around orthodontic appliances: an in vivo
study. Am J Orthod Dentofacial Orthop 1987;92:33–40.
4. Gorton J, Featherstone JD. In vivo inhibition of demineralization around orthodontic brackets. Am J Orthod
Dentofacial Orthop 2003;123:10–14.
5. Pascotto RC, Navarro MF, Capelozza Filho L, Cury JA. In
vivo effect of a resin-modified glass ionomer cement on
enamel demineralization around orthodontic brackets. Am J
Orthod Dentofacial Orthop 2004;125:36–41.
6. de Moura MS, de Melo Simplício AH, Cury JA. In-vivo
effects of fluoridated antiplaque dentifrice and bonding
material on enamel demineralization adjacent to orthodontic appliances. Am J Orthod Dentofacial Orthop 2006;130:
357–63.
7. Sudjalim TR, Woods MG, Manton DJ, Reynolds EC.
Prevention of demineralization around orthodontic brackets
in vitro. Am J Orthod Dentofacial Orthop 2007;131:
705e1–9.
8. Kumar VL, Itthagarun A, King NM. The effect of casein
phosphopeptide-amorphous calcium phosphate on remineralization of artificial caries-like lesions: an in vitro study.
Aust Dent J 2008;53:34–40.
9. Uysal T, Amasyali M, Koyuturk AE, Sagdic D. Efficiency of
amorphous calcium phosphate-containing orthodontic composite and resin modified glass ionomer on demineralization
evaluated by a new laser fluorescence device. Eur J Dent
2009;3:127–34.
10. Diniz MB, Leme AF, Cardoso KD, Rodrigues JD, Cordeiro
RD. The efficacy of laser fluorescence to detect in vitro
DO ACP-CONTAINING COMPOSITE RESINS PREVENT DEMINERALISATION?
11.
12.
13.
14.
demineralization and remineralization of smooth enamel
surfaces. Photomed Laser Surg 2009;27:57–61.
Shapiro S, Meier A, Guggenheim B. The antimicrobial activity of essential oils and essential oil components towards oral
bacteria. Oral Microbiol Immunol 1994;9:202–8.
Hu W, Featherstone JD. Prevention of enamel demineralization: an in vitro study using light-cured filled sealant. Am J
Orthod Dentofacial Orthop 2005;128:592–600.
Featherstone JB, ten Cate JM, Shariati M, Arends J.
Comparison of artificial caries-like lesion by quantitative
microradiography and microhardness profiles. Caries Res
1983;17:385–91.
Dunn WJ. Shear bond strength of an amorphous calciumphosphate-containing orthodontic resin cement. Am J
Orthod Dentofacial Orthop 2007;131:243–7.
15. Uysal T, Ulker M, Akdogan G, Ramoglu SI, Yilmaz E. Bond
strength of amorphous calcium phosphate-containing orthodontic composite used as a lingual retainer adhesive. Angle
Orthod 2009;79:117–21.
16. Shen P, Cai F, Nowicki A, Vincent J, Reynolds EC.
Remineralization of enamel subsurface lesions by sugar-free
chewing gum containing casein phosphopeptide-amorphous
calcium phosphate. J Dent Res 2001;80:2066–70.
17. Reynolds EC, Cai F, Shen P, Walker GD. Retention in
plaque and remineralization of enamel lesions by various
forms of calcium in a mouthrinse or sugar-free chewing
gum. J Dent Res 2003;82:206–11.
18. Rose RK. Binding characteristics of streptococcus mutans
for calcium and casein phosphopeptide. Caries Res 2000;34:
427–31.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
15
Cytotoxicity of orthodontic separating elastics
Matheus Melo Pithon, Rogério Lacerda dos Santos, Fernanda Otaviano Martins,
Maria Teresa Villela Romanos and Mônica Tirre de Souza Araújo
Federal University of Rio de Janeiro-UFRJ, Rio de Janeiro, Brazil
Background: Separating elastics may be cytotoxic to the interdental gingival tissues. Both latex and non-latex separating elastics
are widely used and both types should be biocompatible.
Objective: To determine if latex and non-latex orthodontic separating elastics are cytotoxic.
Methods: The cytotoxicity of natural latex (Groups A, D and O) and non-latex (Group M) orthodontic separating elastics were
determined by incubating 15 elastics of each type in Eagle’s essential medium (MEM), removing the supernatant after 24, 48,
72 and 168 hours and adding it to cultures of L-929 mouse fibroblasts in growth medium (MEM plus glutamine, garamicine,
fungizone, sodium bicarbonate, buffered saline and foetal calf serum). To verify the cell response in extreme situations, three
additional groups were included: Group CC (cell control), consisting of L-929 cells not exposed to supernatants from the maintenance medium with the elastics; Group C+ (positive control), consisting of Tween 80; Group C- (negative control), consisting
of phosphate buffered saline solution. The positive and negative controls were incubated in MEM maintenance medium for 24,
48, 72 and 168 hours and the extracted elutes were added to L-929 line cells incubated in the growth medium. The viability
of the cells was determined with neutral red (dye-uptake method) at 24, 48, 72 and 168 hours. The data were analysed with
the analysis of variance (ANOVA) and Tukey’s multiple comparison test. The significance level was p ≤ 0.05.
Results: The elastics in Groups A, D and O induced greater cell lysis at 72 hours compared to the other experimental times.
There were statistically significant differences between the cytotoxicity of the elastics in Groups A, D and O in relation to
Group CC for experimental times of 24, 48, 72 and 168 hours (p > 0.05). There was not, however, a statistically significant
difference between Groups D and CC at 24 hours.
Conclusion: The latex and non-latex orthodontic separating elastics tested were considered to be biocompatible.
(Aust Orthod J 2010; 26: 16–20)
Received for publication: June 2009
Accepted: August 2009
Matheus Melo Pithon: matheuspithon@bol.com.br
Rogério Lacerda dos Santos: lacerdaorto@hotmail.com
Fernanda Otaviano Martins: fernandamartins@gmail.com
Maria Teresa Villela Romanos: teresaromanos@micro.ufrj.br
Mônica Tirre de Souza Araújo: monicatirre@gmail.com
Introduction
Recent studies have been concerned with the biocompatibility of different types of orthodontic
materials.1,2 Separating elastics made from natural
rubber and non-latex materials are commonly used
prior to orthodontic treatment. Allergic reactions
caused by latex proteins have been well-documented,
but little is known if latex and non-latex products are
cytotoxic to oral mucosal cells.3–9
Cell lines, such as L-929 mouse fibroblasts, have been
shown to behave similarly to human gingival fibroblasts and, therefore, are a suitable in-vitro model to
test the toxicity of products used intra-orally during
16
Australian Orthodontic Journal Volume 26 No. 1 May 2010
orthodontic treatment.10–14 The objective of this invitro study was to determine if latex and non-latex
orthodontic separating elastics are cytotoxic.
Materials and methods
Fifteen blue-coloured elastics (Diameter: 4.4 mm)
from four manufacturers were assigned to the following groups: Group M, silicone (non-latex) modular
elastics (Masel, Bristol, PA, USA); Group D, natural
latex modular elastics (Dentaurum, Ispringen,
Germany); Group A, natural latex bulk pack elastics
(Aditek, Cravinhos, São Paulo, Brazil); Group O,
natural latex bulk pack elastics (OrthoSource, North
© Australian Society of Orthodontists Inc. 2010
CYTOXICITY OF ORTHODONTIC SEPARATING ELASTICS
Table I. Experimental and control groups used for the assays.
Groups
Trademark/Firm
Composition
M
D
A
O
C+
C-
Masel
Dentaurun
Aditek
OrthoSource
Tween 80
PBS solution
Non-latex
Natural latex
Natural latex
Natural latex
External
diameter
(mm)
Reference
number
Batch
number
4.4
4.4
4.4
4.4
4108-720
774-200-01
159341
00424-625
132864
401783
081126
205874
at 37 °C. This ensured that the cells adhered to
the microplates. After 48 hours, the growth medium
was replaced with 100 µl of MEM in which the
elastics had been incubated for 24, 48, 72 and 168
hours.
Figure 1. Intra-oral separating elastics tested: M (Masel), D (Dentaurum), A
(Aditek) and O (OrthoSource).
Hollywood, CA, USA) (Figure 1). All samples had
recent manufacturing dates, were from the same production lot and came in sealed plastic packages.
Before testing, the powder coating was removed by
washing the elastics for 15 seconds with deionised
water in a Milli-Q purification system (Millipore,
Bedford, MA, USA). The elastics were then sterilised
by exposure to ultraviolet light (Labconco, Kansas,
MO, USA) for 30 minutes.15,16
Volumes of 100 µl L-929 line cells (American Type
Culture Collection – ATCC, Rockville, MD, USA)
and growth medium consisting of Eagle’s minimum
essential medium (MEM, Cultilab, Campinas,
Brazil) plus 0.03 mg/ml of glutamine (Sigma, St.
Louis, MO, USA), 50 µg/ml of garamicine (Schering
Plough, Kenilworth, NJ, USA), 2.5 mg/ml of fungizone (Bristol-Myers-Squibb, New York, NY, USA),
0.25 per cent sodium bicarbonate solution (Merck,
Darmstadt, Germany), 10 mmol of HEPES (Sigma,
St. Louis, MO, USA) and 10 per cent bovine foetal
serum (Cultilab, Campinas, Brazil) were distributed
into 96-well microplates and incubated for 48 hours
To verify the cell response in extreme situations, three
additional groups were included in the study: Group
CC (cell control), consisting of L-929 cells not
exposed to supernatants from the elastics; Group C+
(positive control), consisting of Tween 80
(Polyoxyethylene-20-sorbitan, Sigma, St. Louis, MO,
USA); Group C- (negative control), consisting of
phosphate-buffered saline (PBS) solution (Table I).
The positive and negative controls were incubated in
MEM maintenance medium for 24, 48, 72 and 168
hours and the extracted elutes were added to L-929
line cells incubated in the growth medium.
Dye uptake
The cytotoxicity of the orthodontic elastics was determined with the dye-uptake method, which is based
on the uptake of neutral red by living cells.17 After 24
hours incubation, 100 µl of 0.01 per cent neutral red
dye (Sigma, St. Louis, MO, USA) was added to each
well in the microplates and incubated for 3 hours at
37 °C. Following this period of time, 100 µl of 4 per
cent formaldehyde solution (Vetec, Rio de Janeiro,
Brazil) in PBS (130 mmol of NaCl; 2 mmol of KCl;
6 mmol of Na2HPO4 2H2O; 1 mmol of K2HPO4
1 mmol; pH 7.2) were added to each well to promote
cell attachment to the plate. After 5 minutes, 100 µl
of 1 per cent acetic acid (Vetec, Rio de Janeiro, Brazil)
and 50 per cent methanol (Vetec, Rio de Janeiro,
Brazil) were added in order to remove the dye not
taken up by the cells. After 20 minutes, a spectrophotometer (BioTek, Winooski, VT, USA) set at a
Australian Orthodontic Journal Volume 26 No. 1 May 2010
17
SANTOS ET AL
Table II. Cell viability at 24, 48, 72 and 168 hours.
Groups
N
Mean
Median
SD
Cell viability
(Per cent)
Time 24 hours
CC
C+
M
D
A
O
15
15
15
15
15
15
0.680
0.061
0.660
0.642
0.631
0.634
a
a
ab
b
b
15
15
15
15
15
15
15
0.660
0.653
0.060
0.642
0.608
0.594
0.605
a
a
b
b
b
Median
SD
Cell viability
(Per cent)
0.735
0.070
0.710
0.698
0.682
0.678
0.08
0.01
0.052
0.07
0.04
0.08
100.0
8.3
96.9
94.6
92.6
93.1
0.708
0.698
0.074
0.690
0.666
0.658
0.670
0.08
0.03
0.01
0.08
0.06
0.05
0.08
100.0
98.4
8.9
97.5
95.0
93.0
94.1
Time 48 hours
0.710
0.078
0.668
0.658
0.650
0.646
0.08
0.01
0.04
0.04
0.07
0.07
100.0
9.1
97.2
94.5
92.9
93.3
Time 72 hours
CC
CC+
M
D
A
O
Mean
0.720
0.059
0.697
0.681
0.66
0.670
a
ab
bc
c
bc
Time 168 hours
0.664
0.710
0.068
0.658
0.622
0.604
0.616
0.08
0.05
0.01
0.08
0.07
0.06
0.08
100.0
99.0
9.1
97.3
92.2
90.1
91.7
0.694
0.682
0.061
0.676
0.659
0.645
0.653
a
ab
b
b
b
Values followed by same letters are not significantly different (p > 0.05) for the same time.
wavelength of 492 nm was used to determine the dye
taken up by the cells. This test was repeated three
times and each test used samples of the media
obtained by incubating 15 new elastics from each
group for 24, 48, 72 and 168 hours. Because separating elastics can be in the oral cavity for up to 7 days
(168 hours) cell viability was determined after
exposure to MEM in which the elastics had been
incubated for 24, 48, 72 and 168 hours.
Data were compared with an analysis of variance
(ANOVA) and Tukey’s multiple comparison test was
used to identify statistically significant differences
between the groups. The significance level was set at
p ≤ 0.05.
Results
There were no statistically significant differences
between the viability of the cells in Groups CC, M
and D at 24 hours or between Groups CC and M at
48, 72 and 168 hours. Nor were there any statistically significant differences between the viability of the
cells in Groups D, A and O at 24, 48 and 72 hours,
between Groups M, D and O at 48 hours or Groups
M, D, A and O at 168 hours (Table II). No statistically significant differences were observed between
Groups M and CC at any experimental time and
18
Australian Orthodontic Journal Volume 26 No. 1 May 2010
between M and D groups at 24, 48 and 168 hours
(p > 0.05). There were fewer viable cells in Groups
D, A and O at 72 hours compared to the other
experimental times (Table II, Figure 2).
At 24 hours the percentage of viable cells varied
between 97.2 per cent in Group M with the silicone
polymer separator to 92.9 per cent in Group A with
a natural rubber latex separating elastic. The percentage of viable cells fell slightly over the following 24
hours in Groups M, A and O, continued to fall in
Groups D, A and O between 48 and 72 hours and
increased between 72 and 168 hours.
Discussion
In this cross-sectional study we evaluated the cytotoxic effects of latex and non-latex separating elastics
on cultures of mouse fibroblasts. We used the vital
dye neutral red, which stains viable cells only, and
measured the optical density of the cells with a spectrophotometer. We determined the percentage of viable
cells by comparing the mean optical density of the
cells in the control group, which had no contact with
the elastics, with the mean optical densities of the
cells in contact with supernatants in which the
elastics had been incubated for varying periods of
time. The supernatants from the groups with latex
CYTOXICITY OF ORTHODONTIC SEPARATING ELASTICS
investigate further whether colourants affect cell viability as they appear to have leached from the surface
layers of the elastics in the first 24 hours. However, by-products from latex elastics are known to be
cytotoxic.3,14,19
Spectrophotometric assay is a rapid and reliable
method of determining cell viability. We used neutral
red dye as it is widely used to check L-929 cell viability. Dead or damaged cells did not take up the vital
stain and were not recognised by the assay.
Spectrophotometry does not, however, distinguish
dead and damaged cells.
Although L-929 mouse fibroblasts behave similarly to
primary human gingival fibroblasts, the cell culture
results are only a guide to the human response.12,13
Protocols for direct contact cytotoxicity tests vary
widely. Assays using L-929 mouse fibroblasts have
been shown to give comparable results to cultures of
human gingival fibroblasts, and are considered to be
an acceptable model for testing the toxicity of substances to gingival fibroblasts in vitro.10–13 There are,
however, some limitations to the method: cyotoxicity
assays of the same material can give different results
because of differences in production of the cytotoxic
substance(s) and different cell surface/volumes in the
culture medium. Internationally standardised protocols are obviously needed to obtain comparable
results and to further develop cytotoxicity screening
tests for the dental materials used in patients.13
Figure 2. Percentage viability of tested elastics obtained by
spectrophotometry.
elastics had lower cell viabilities compared to the
group with silicone polymer separating elastics. There
was no significant variation in cell viability in the
latter group over the experimental period, although
the cell viability in all groups increased slightly at 168
hours.
The cytoxicity of the supernatants may be due to byproducts from the latex elastics or the colourants in
the separating elastics. The latter appears to be an
unlikely cause for cell death as Holmes et al.18
reported that the colourants in orthodontic elastics
had low toxicity and could be regarded as ‘clinically inoffensive’. Short-term studies are needed to
Silicone separating elastics were shown to have
similar cytotoxicity to the latex separating elastics. We
removed the powder coating from the elastics beforehand in order to standardise the samples and ensure
that it did not influence the results. We could not
determine if the powder was cytotoxic or if it contributed to the cytotoxicity of the elastics. According
to Schmalz,14 potentially cytotoxic intra-oral
elastics could release harmful substances that might
accumulate in the body and over time initiate a
disease process. It is known that latex is not entirely
biocompatible and it may interact with certain
foods5,20 and medications.21
The natural latex separating elastics induced more cell
lysis at 72 hours than at 24, 48 and 168 hours, suggesting that toxic substances were ‘released’ after 72
hours. These substances could be due to degradation
products and/or the release of harmful proteins from
the latex itself. Our finding that the process was not
Australian Orthodontic Journal Volume 26 No. 1 May 2010
19
SANTOS ET AL
continuous is supported by Holmes et al. who
reported that natural latex elastics were biocompatible after 3 days intra-oral use.18 As these materials are
widely used in clinical orthodontics and are in intimate contact with the gingival tissues, they should be
used sparingly or replaced by proven biocompatible
materials.
The elastics we tested showed over 90 per cent cell
viability after 3 days. Other investigators have
reported that latex elastics cause more cell death (up
to 50 per cent) than non-latex elastics, but concluded
that both types of elastic (latex and non-latex) could
be used in orthodontics.22 We conclude that the latex
and non-latex orthodontic separating elastics we
tested have acceptable biocompatibilies, but elastics
with cell viabilities less than 50 per cent should be
avoided.14
Corresponding author
Dr Mônica Tirre de Souza Araújo
Universidade Federal do Rio de Janeiro - UFRJ
Faculdade de Odontologia - Departamento de
Ortodontia
Av. Prof. Rodolpho Paulo Rocco
325 Ilha do Fundão
Rio de Janeiro – RJ Brasil CEP: 21941-617
Email: monicatirre@gmail.com
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
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Vande Vannet BM, Hanssens JL. Cytotoxicity of two bonding adhesives assessed by three-dimensional cell culture.
Angle Orthod 2007;77:716–22.
Kao CT, Ding SJ, He H, Chou MY, Huang TH.
Cytotoxicity of orthodontic wire corroded in fluoride
solution in vitro. Angle Orthod 2007;77:349–54.
Fiddler W, Pensabene J, Sphon J, Andrzejewski D.
Nitrosamines in rubber bands used for orthodontic purposes. Food Chem Toxicol 1992;30:325–6.
Hwang CJ, Cha JY. Mechanical and biological comparison
of latex and silicone rubber bands. Am J Orthod Dentofacial
Orthop 2003;124:379–86.
Turjanmaa K, Alenius H, Makinen-Kiljunen S, Reunala T,
Palosuo T. Natural rubber latex allergy. Allergy 1996;51:
593–602.
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Tomazic VJ, Withrow TJ, Fisher BR, Dillard SF. Latex-associated allergies and anaphylactic reactions. Clin Immunol
Immunopathol 1992;64:89–97.
Everett FG, Hice TL. Contact stomatitis resulting from the
use of orthodontic rubber elastics: report of case. J Am Dent
Assoc 1974;88:1030–31.
Wakelin SH, White IR. Natural rubber latex allergy. Clin
Exp Dermatol 1999;24:245–8.
Palosuo T, Alenius H, Turjanmaa K. Quantitation of latex
allergens. Methods 2002;27:52–8.
Schmid-Schwap M, Franz A, Konig F, Bristela M, Lucas T,
Piehslinger E et al. Cytotoxicity of four categories of dental
cements. Dent Mater 2009;25:360–8.
Franz A, Konig F, Lucas T, Watts DC, Schedle A. Cytotoxic
effects of dental bonding substances as a function of degree
of conversion. Dent Mater 2009;25:232–9.
Schedle A, Samorapoompichit P, Rausch-Fan XH, Franz A,
Fureder W, Sperr WR et al. Response of L-929 fibroblasts,
human gingival fibroblasts, and human tissue mast cells to
various metal cations. J Dent Res 1995;74:1513–20.
Franz A, Konig F, Skolka A, Sperr W, Bauer P, Lucas T et al.
Cytotoxicity of resin composites as a function of interface
area. Dent Mater 2007;23:1438–46.
Schmalz G. Use of cell cultures for toxicity testing of dental
materials – advantages and limitations. J Dent 1994;22
Suppl 2:S6–11.
Santos RL, Pithon MM, Oliveira MV, Mendes GS, Romanos
MT, Ruellas AC. Cytotoxicity of intraoral orthodontic
elastics. Braz J Oral Sci. 2008;7:1520–5.
Santos RL, Pithon MM, Mendes GS, Romanos MT, Ruellas
AC. Cytotoxicity of intermaxillary orthodontic elastics of
different colors: An in vitro study. J Appl Oral Sci 2009;17:
326–9.
Neyndorff HC, Bartel DL, Tufaro F, Levy JG. Development
of a model to demonstrate photosensitizer-mediated viral
inactivation in blood. Transfusion 1990;30:485–90.
Holmes J, Barker MK, Walley EK, Tuncay OC. Cytotoxicity
of orthodontic elastics. Am J Orthod Dentofacial Orthop
1993;104:188–91.
Perrella FW, Gaspari AA. Natural rubber latex protein
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Carey AB, Cornish K, Schrank P, Ward B, Simon R. Crossreactivity of alternate plant sources of latex in subjects with
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Hanson M, Lobner D. In vitro neuronal cytotoxicity of latex
and nonlatex orthodontic elastics. Am J Orthod Dentofacial
Orthop 2004;126:65–70.
Porcelain brackets during initial alignment: are
self-ligating cosmetic brackets more efficient?
Peter Miles * and Robert Weyant †
Private practice, Caloundra, Queensland, Australia* and the Division of Pediatric and Developmental Dental Sciences, School of Dental
Medicine, University of Pittsburgh, Pittsburgh, U.S.A.†
Objective: To compare the effectiveness of a self-ligating (SL) porcelain bracket with a conventional porcelain (CP) bracket tied
with ligatures for initial alignment in the upper arch, to compare the discomfort of both bracket – archwire combinations and to
compare the times taken (both assisted and unassisted) to untie and ligate both bracket – archwire combinations.
Methods: Sixty nonextraction patients were randomly assigned to either a group with CP brackets on the upper six anterior
teeth and conventional metal brackets on the premolars and first molars, or a group with SL porcelain brackets on the anterior
teeth and SL metal brackets on the posterior teeth. The CP brackets were tied with coated ligatures. The irregularity index was
measured at the start of treatment and at the first recall 10.7 weeks later. Discomfort was recorded over the first week with a
Likert scale and the times to untie and ligate the six anterior porcelain brackets (assisted and unassisted) were recorded.
Results: There were no differences in irregularities at the start of treatment (p = 0.91) or 10.7 weeks later (p = 0.12). No significant difference in discomfort was found between the bracket types (p = 0.90). The porcelain SL brackets were significantly
faster (p < 0.001) to untie and ligate than the CP brackets with ligatures.
Conclusion: Porcelain SL brackets were faster to untie and ligate by 22 seconds per bracket, but there were no significant
differences in the alignment achieved or discomfort experienced.
(Aust Orthod J 2010; 26: 21–26)
Received for publication: September 2009
Accepted: October 2009
Peter Miles: pmiles@beautifulsmiles.com.au
Robert Weyant: rjwl@pitt.edu
Introduction
Although self-ligating (SL) brackets have been available for many years they have recently become
popular with clinicians because of claims that they
result in shorter treatment times. There is some evidence that these brackets can be ligated quickly and
have less friction than conventional brackets.1–3
Many of these claims have been based on evidence
from retrospective clinical studies, which may be confounded by factors such as the proficiency of the
clinician(s), the treatment mechanics used and/or
observer bias.4,5 Randomised clinical trials attempt to
overcome the shortcomings of retrospective trials, but
they may have limitations also, such as the use of
archwires with different dimensions.6 Prospective
clinical trials that have used identical wire sequences
found no difference in the ability to align anterior teeth
between SL brackets and conventional brackets.7–13
© Australian Society of Orthodontists Inc. 2010
There is little doubt that the latches on SL brackets
can be unfastened and closed more quickly than elastomeric modules or wire ligatures can be removed and
placed on conventional brackets. Time savings of up
to 10–12 minutes per patient for SL brackets compared with tying steel ligatures and 2–3 minutes
compared with elastomeric modules have been
reported.1,5,14,15 Many patients would like their treatment to be as short and as inconspicuous as possible,
and for these reasons they prefer to have porcelain or
plastic brackets bonded on their upper anterior teeth.
The aims of this study are to compare the effectiveness of SL porcelain brackets with conventional porcelain (CP) brackets tied with ligatures for initial
alignment in the upper arch, to compare the discomfort
of both bracket – archwire combinations and to compare the times taken (both assisted and unassisted) to
untie and ligate both bracket – archwire combinations.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
21
Randomised
(N = 68)
Group 2
Allocated to Clarity (N = 34)
Received allocated intervention (N = 34)
Follow-up
Group 1
Allocated to In-Ovation C (N = 34)
Received allocated intervention (N = 34)
Lost to follow-up (N = 0)
Impression missed (N = 2)
Lost to follow-up (N = 0)
Impression missed (N = 4)
Analysis
Allocation
Enrolment
MILES AND WEYANT
Analysed (N = 30)
Excluded from analysis (N = 2)
Analysed (N = 30)
Excluded from analysis (N = 0)
Figure 1. Flow chart showing the progress of patients through the trial.
Sixty-eight consecutive subjects, scheduled for nonextraction treatment in the upper arch, were drawn
from the senior author’s private orthodontic practice.
All subjects agreed to participate in the study after the
purpose had been explained to them. The subjects
were not informed which bracket was the newer
design.
Of the 68 patients enrolled in the study, follow-up
impressions were missed for two subjects in Group 1
and four subjects in Group 2 (Figure 1). Two subjects, matched for age, gender and incisor irregularity
with two subjects in Group 2, were dropped from
Group 1 to keep the same number of subjects in each
group. At analysis both groups had 19 female subjects
and 11 male subjects. The overall mean age at the
conclusion of the trial was 13.5 + 1.5 years.
The subjects were randomly allocated to one of two
groups. In Group 1, SL porcelain 0.018 inch InOvation C brackets (GAC International, Bohemia,
NY, USA) were indirectly bonded to the upper
incisors and canines and metal In-Ovation brackets
were indirectly bonded on the upper premolars and
first molars. In Group 2, conventional porcelain (CP)
0.018 inch Clarity brackets (3M/Unitek, Monrovia,
CA, USA) were bonded indirectly to the upper
incisors and canines and Victory brackets (3M/
Unitek, Monrovia, CA, USA) were bonded to the
upper premolars and first molars.
Alginate impressions for study models were taken
prior to bonding. Immediately after bonding a 0.014
inch G4 heat-activated NiTi wire (G & H Wire
Company, Franklin, IN, USA) was placed in each
subject. To prevent the archwire from sliding around
the arch and interfering with the incisors during
alignment, V-bends were placed distal to each central
incisor. The six anterior CP brackets were ligated with
coated ligatures while elastomeric modules (3M
Unitek, Monrovia, CA, USA) were used on the premolars. The SL In-Ovation brackets were ‘ligated’
using the clip mechanism in the bracket. The first
Subjects and methods
22
Australian Orthodontic Journal Volume 26 No. 1 May 2010
ARE SELF-LIGATING COSMETIC BRACKETS MORE EFFICIENT?
Table I. Irregularity scores for each bracket type, in millimetres.
Table II. Ratings of upper arch discomfort for each bracket type.
Time
In-Ovation C
Mean (SD)
Clarity
Mean (SD)
p
T1
T2
7.0 (3.4)
2.3 (1.0)
7.1 (3.0)
2.7 (1.1)
0.91
0.12
T1, pretreatment; T2, recall at approximately 10.7 weeks
wire change was scheduled approximately 10 weeks
after bonding, at which time a second alginate
impression and photographs were taken of the
upper arch.
The alginate impressions were poured up in dental
stone for later measurement of the irregularity
index.16 The irregularity index, defined as the summed
displacement of adjacent anatomical contact points
of the six anterior teeth, was measured using a digital
caliper to the nearest 0.1 mm with the operator
blinded to the identity of each cast.
The irregularity data before the start of the trial (T1)
and after approximately 10 weeks (T2) were compared with a one-way analysis of variance (ANOVA).
The irregularity data were also divided into two subgroups: subjects with an initial irregularity score < 5.0
mm and subjects with an initial irregularity score
≥ 5.0 mm.6
To assess the accuracy of measuring the irregularity
index, 10 models were randomly selected and
remeasured one month after the first set of measurements. Pearson’s correlation coefficient and a paired
t-test were used to assess the accuracy and reproducibility of the method. There was no significant
difference between the two sets of measurements
(Mean difference: 0.06 mm, p = 0.76, r = .98)
indicating that the irregularity measurements were
reliable.
To assess the discomfort with each type of bracket,
the subjects were asked to record the levels of discomfort in the upper arch on a 7-point Likert scale
4 hours, 24 hours, 3 days and 1 week after placement
of the initial archwire. They were also asked to return
the questionnaires at the following visit. The 4-, 24hour, 3-day and 1-week and total discomfort scores
were compared with a one-way ANOVA and with
post-hoc Tukey’s HSD test for multiple comparisons.
The times taken by the senior author to untie and
ligate 10 consecutive cases from each group, and the
Time
In-Ovation C
Mean rating (SD)
4-hours
1-day
3-days
7-days
Total
2.8
3.4
2.5
1.6
10.2
(1.5)
(1.8)
(1.5)
(1.1)
(5.2)
Clarity
Mean rating (SD)
2.4
3.9
2.4
1.3
10.1
(1.1)
(1.7)
(0.9)
(0.6)
(3.2)
p
0.42
0.33
0.87
0.29
0.90
Table III. Times taken to untie and ligate six porcelain brackets unassist-
ed and assisted by a staff member, in seconds.
In-Ovation C
Mean (SD)
Clarity
Assisted
Clarity
Unassisted
Untying 9.2 (2.5) a,b 31.5 (10.2) a
32.2 (12.9) b
Ligating 12.4 (6.3) a,b 91.2 (5.8) a,c 119.6 (8.7) b,c
Total
21.6 (7.5) a,b 122.7 (10.1) a,c 151.8 (16.3) b,c
The letters indicate groups significantly different at p < 0.001 with
Tukey’s HSD test.
times taken by the senior author assisted by a staff
member to untie and ligate the CP brackets in 10
consecutive subjects were compared with a one-way
ANOVA.
Results
There were no statistically significant differences
between the irregularity scores in the groups either
pretreatment (T1) or 10.7 weeks later (T2). At T2
the anterior teeth in the self-ligating group were
slightly less irregular than the anterior teeth in the
Clarity group, but the difference was not statistically
significant (Table I).
When the irregularity data were subdivided into the
low irregularity (< 5 mm) and high irregularity
(≥ 5 mm) subgroups, there were no statistically
significant group differences at T1 (Low irregularity
subgroup: SL vs CP, p = 0.92; High irregularity subgroup: SL vs CP, p = 0.63) or T2 (Low irregularity
subgroup: SL vs CP, p = 0.95; High irregularity subgroup: SL vs CP, p = 0.11).
Of the 60 patients who completed the study, 42 (70
per cent) returned the discomfort questionnaires. To
determine if there was any difference in the irregularity scores of those who returned the questionnaires
Australian Orthodontic Journal Volume 26 No. 1 May 2010
23
MILES AND WEYANT
and those who did not, the T2 irregularity scores of
these two subgroups were compared. There were no
statistically significant differences between the irregularity scores of the SL subjects either with or without
pain scores (p = 0.85) or for the CP subjects with or
without pain scores (p = 0.19). There were no statistically significant group differences in the subjects’
ratings of discomfort at any of the time intervals or in
the total rating (Table II).
The times to untie and ligate the six anterior SL
brackets unassisted and the six anterior CP brackets
unassisted and assisted, are given in Table III. The SL
brackets could be untied and ligated significantly
faster than the CP brackets either assisted or unassisted
(p < 0.001). On average, the SL brackets could be
untied and ligated 1 minute 41 seconds (assisted) or
2 minutes 10 seconds (unassisted) less than the CP
brackets. The help of an assistant saved no time when
untying the CP bracket (p = 0.89), but tying ligatures
with the help of an assistant saved 29 seconds for the
six CP brackets (p < 0.001).
Discussion
We found that SL and CP brackets with 0.014 inch
NiTi archwires were equally effective at aligning the
upper six anterior teeth and that our subjects considered both bracket – archwire combinations equally
uncomfortable. We did, however, find significant
savings in the times required to untie and ligate the
SL brackets over the CP brackets, which is hardly surprising as the SL brackets were closed with a latch,
whereas the CP brackets were ligated with coated ligatures. An assistant significantly reduced the time
required to ligate the CP brackets.
Coated ligatures were used on the CP brackets as
elastomeric modules could not be tied in a figure-8
on these ceramic brackets. The ligatures ensured that
the archwire was seated in the bracket slots. Small,
but statistically significant, improvements in alignment have been reported for conventional metal
brackets tied with either modules in a figure-8 pattern
or steel ligatures over passive SL brackets.7,8 On the
other hand, no statistically significant differences in
lower arch alignment were found between SL brackets
and metal conventional brackets,9–11 or between
active and passive SL brackets in upper arch aligment.17
In addition to the method of ligation, factors such as
tooth shape, slot dimensions, bracket width and
bracket position may influence alignment. We
24
Australian Orthodontic Journal Volume 26 No. 1 May 2010
limited the variation due to bracket position by
using an indirect bonding technique and randomly
assigning the subjects to both groups.
As we found no difference in alignment, the small
differences reported in previous studies could be
due to the use of a passive rather than an active SL
bracket. The bracket geometry may also be a factor as
some SL brackets are narrower than conventional
brackets and offer less rotational control. A recent
study comparing an active SL bracket with a passive
SL bracket in the upper arch found no significant difference in the time required to attain alignment,17
and a study comparing plastic/metal Damon 3 SL
brackets with conventional metal brackets ligated
with elastomeric modules also found no difference
during initial alignment in the lower arch.9
In agreement with previous studies we found no significant difference in the ratings of discomfort
between the different brackets.18–20 In other words,
the SL bracket – archwire combination was no more
uncomfortable during initial alignment than the CP
bracket – archwire combination. On four out of five
occasions the Clarity group ratings were slightly less,
but not significantly so, than the ratings by the InOvation C group. The lack of significant findings
could also be due to the lack of sensitivity of the
Likert rating scale, because the raters had different
frames of reference or because they were influenced
by what they thought was the purpose of the scale.
The Likert scale was used in this study to enable our
results to be compared with other studies using the
same method.
A previous study reported that SL brackets were no
more efficient in terms of the time required to align
incisors with high irregularity scores (≥ 5 mm) than
conventional brackets, but incisors with low irregularity scores (< 5 mm) were aligned more quickly with
SL brackets.6 In that study two different wire
sequences were used for each bracket type: the second
archwire in the conventional bracket group was a
round wire whereas a rectangular archwire was used
in the SL bracket group. Use of archwires with different cross-sections may have accounted for the different results. We used identical archwires in both
groups and found no significant difference between
the subjects with low irregularity scores (< 5 mm) and
those with high scores (≥ 5 mm).
Anecdotal reports have suggested that high canines
respond more favourably to the lesser friction of SL
ARE SELF-LIGATING COSMETIC BRACKETS MORE EFFICIENT?
Figure 2. Subjects with high canines. Both subjects had 0.014 inch heat-activated NiTi archwires.
Top left, Group 1 subject at T1; Top centre, the same Group 1 subject at T1; Top right, the same Group 1 subject at T2 (CP and metal brackets).
Bottom left, Group 2 subject at T1; Bottom centre, the same Group 2 subject at T1; Bottom right, the same Group 2 subject at T2 (SL porcelain and SL metal
brackets).
brackets. We subjectively assessed the subjects in our
study and found four with high canines: two subjects
in each group. The mean irregularities reduced from
12.0 mm to 1.8 mm in the subjects with CP brackets
and from 11.4 mm to 1.2 mm in the subjects with SL
brackets (Figure 2). In both cases the mean improvement in alignment was identical at 10.2 mm. This is
not unexpected as displacement of the archwire into
the bracket on a high canine can result in the archwire binding and notching, which are the major
contributors to resistance to sliding.
In the present study, untying and ligating SL brackets
on the upper anterior teeth saved a small, but statistically significant, amount of time over the time
required to untie and ligate the CP brackets. Without
help from an assistant the time saved with six anterior SL brackets averaged 2 minutes 10 seconds or 22
seconds per bracket compared with a ligature tie on
each CP bracket. Extrapolating this time saving to 20
SL brackets in both arches could save approximately
7 minutes 20 seconds over CP brackets tied with
ligatures. This time saving is less than the saving of
10–12 minutes reported by others when using
ligatures.14 Although the time savings were small, a
potential saving of 2 minutes 10 seconds at each visit
could add up to approximately 32 minutes over the
course of 15 visits if ligatures were replaced at every
visit.
During initial alignment it is important to engage the
wire completely to gain the maximal correction of
rotations and vertical alignment. Once alignment has
been achieved, elastomeric modules, which can be
placed more quickly, can be used to maintain the correction and time savings would be less. The time
savings of SL brackets compared with modules are in
the order of one minute for both arches.5,15 This represents only a portion of the actual chair time during
an orthodontic adjustment and, depending upon the
utilisation of staff and flow of patients in the office,
may have little impact upon practice efficiency. In
some circumstances small gains in efficiency may be
possible if the orthodontist works unaided. However,
if an auxiliary ligates the archwire and the orthodontist is not available to check the patient, efficiency will
depend upon the availability of the orthodontist
rather than the method of ligation. In some cases,
such as using chain or a long ligature to close or consolidate space closure or prevent spaces opening,
having to close a clip or gate on an SL bracket as well
as tying a chain or ligature could actually add a small
Australian Orthodontic Journal Volume 26 No. 1 May 2010
25
MILES AND WEYANT
amount of time compared with a conventional
bracket. Finally, the bracket and ligation mechanism
need to be reliable throughout the course of treatment. If a clip or gate ‘locks’ and cannot be opened,
or distorts or breaks during treatment, then this can
affect either the time to ligate the bracket and/or the
ability of the bracket to align the tooth if the bracket
is not fully engaging the archwire. Future research
will need to evaluate the full-course of treatment with
detailed records of any difficulties. This is highlighted by a previous retrospective study that found no
difference between an active SL bracket and a conventional bracket in overall treatment time or
number of visits, but reported significantly more
breakages and emergencies using the SL bracket.12
6.
7.
8.
9.
10.
11.
Conclusions
There were no significant differences between selfligating porcelain brackets and conventional porcelain brackets in aligning the upper anterior teeth or
the discomfort experienced by the subjects.
Self-ligating porcelain brackets were significantly
faster to untie and ligate than the conventional
porcelain brackets tied with coated ligatures.
12.
13.
14.
15.
Corresponding author
Dr Peter Miles
10 Mayes Avenue
Caloundra Qld 4551
Australia
Email: pmiles@beautifulsmiles.com.au
16.
17.
References
1.
2.
3.
4.
5.
26
Shivapuja PK, Berger J. A comparative study of conventional ligation and self-ligation bracket systems. Am J Orthod
Dentofac Orthop 1994;106:472–80.
Sims AP, Waters NE, Birnie DJ, Pethybridge RJ. A comparison of the forces required to produce tooth movement in
vitro using two self-ligating brackets and a pre-adjusted
bracket employing two types of ligation. Eur J Orthod 1993;
15:377–85.
Pizzoni L, Ravnholt G, Melsen B. Frictional forces related to
self-ligating brackets. Eur J Orthod 1998;20:283–91.
Eberting JJ, Straja SR, Tuncay OC. Treatment time, outcome, and patient satisfaction comparisons of Damon and
conventional brackets. Clin Orthod Res 2001;4:228–34.
Harradine NW. Self-ligating brackets and treatment
efficiency. Clin Orthod Res 2001;4:220–7.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
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19.
20.
Pandis N, Polychronopoulou A, Eliades T. Self-ligating vs
conventional brackets in the treatment of mandibular
crowding: a prospective clinical trial of treatment duration
and dental effects. Am J Orthod Dentofacial Orthop 2007;
132:208–15.
Miles PG. Smartclip versus conventional twin brackets for
initial alignment: is there a difference? Aust Orthod J
2005;21: 123–7.
Miles PG, Weyant RJ, Rustveld L. A clinical trial of Damon
2 versus conventional twin brackets during initial
alignment. Angle Orthod 2006;6:480–5.
Scott P, DiBiase AT, Sherriff M, Cobourne MT. Alignment
efficiency of Damon 3 self-ligating and conventional orthodontic bracket systems: a randomized clinical trial. Am J
Orthod Dentofacial Orthop 2008;134:470.e1–8.
Fleming PS, DiBiase AT, Lee RT. Randomised controlled
trial of mandibular alignment with two pre-adjusted
appliances. J Orthod 2008;35:223–4 (Abstract).
O’Dwyer LA, Littlewood SJ, Rahman S, Spencer RJ.
Efficiency of SmartClip self-ligating brackets compared to
brackets using conventional ligation. J Orthod 2008;35:226
(Abstract).
Hamilton R, Goonewardene MS, Murray K. Comparison of
active self-ligating brackets and conventional pre-adjusted
brackets. Aust Orthod J 2008;24:102–9.
Justine Brock. A comparison of initial alignment and pain
with self-ligating and conventionally ligated bracket systems.
University of Queensland, Thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of
Clinical Dentistry (Orthodontics), 2008.
Berger J, Byloff FK. The clinical efficiency of self-ligated
brackets. J Clin Orthod 2001;35:304–8.
Turnbull NR, Birnie DJ. Treatment efficiency of conventional vs self-ligating brackets: effects of archwire size and
material. Am J Orthod Dentofacial Orthop 2007;131:
395–9.
Little R. The Irregularity Index: a quantitative score of
mandibular anterior alignment. Am J Orthod 1975;68:
554–63.
Pandis N, Polychronopoulou A, Eliades T. Active or passive
self-ligating brackets? A randomized control trial of comparative efficiency in resolving maxillary anterior crowding in
adolescents. Am J Orthod Dentofacial Orthop 2009;
Accepted for publication.
Scott P, Sherriff M, DiBiase AT, Cobourne MT. Perception
of discomfort during initial orthodontic tooth alignment
using a self-ligating or conventional bracket system: a randomized clinical trial. Eur J Orth 2008;30:227–32.
Rahman S, Spencer RJ, O’Dwyer LA, Littlewood SJ.
SmartClip versus a conventional pre-adjusted edgewise
appliance – Is there a difference in pain and breakages? J
Orthod 2008;35:226–7 (Abstract).
Fleming PS, DiBiase AT, Sarri G, Lee RT. Pain experience
during initial alignment with a self-ligating and a conventional fixed orthodontic appliance system: a randomized
controlled clinical trial. Angle Orthod 2009;79:46–50.
Display of the incisors as functions of age
and gender
Andrea Fonseca Jardim da Motta, * Margareth Maria Gomes de Souza, * Ana Maria
Bolognese, * Clarice Júlia Guerra † and José Nelson Mucha †
Department of Orthodontics, School of Dentistry, Federal University of Rio de Janeiro* and the Department of Clinical Dentistry, School of
Dentistry, Fluminense Federal University,† Rio de Janeiro, Brazil
Background: Older subjects usually show less of their upper incisors and more of their lower incisors than younger subjects.
Objectives: To determine how much of the upper and lower central incisor crowns are visible in Brazilian subjects with their lips
at rest.
Methods: The subjects were 240 white Brazilian subjects divided into four age groups: Group 1, 12 to 15 years of age;
Group 2, 20 to 30 years of age; Group 3, 31 to 50 years of age and Group 4, 51 years of age and older. Each group
contained 30 males and 30 females. The vertical display of the incisors was measured in millimetres from the midpoints of the
incisal edges of the upper and lower central incisors to the borders of the upper and lower lips.
Results: In females, the mean upper central incisor display reduced from 4.45 mm in Group 1 to 1.32 mm in Group 4, and in
males it reduced from 3.35 mm in Group 1 to 0.57 mm in Group 4. Less of the lower central incisor crowns were displayed
in Group 1 females (Mean: 0.47 mm) than in Group 4 females (Mean: 2.22 mm), and in Group 1 males (Mean: 0.61 mm)
than in Group 4 males (Mean: 3.05 mm). Brazilian women showed significantly more of their upper incisor crowns than
Brazilian men in Groups 1, 2 and 4, whereas Brazilian men showed significantly more of their lower central incisors than
Brazilian women in Group 4.
Conclusions: With the lips at rest, older Brazilians display less of their upper central incisors and more of their lower central
incisors than young Brazilians. Women show more of their upper incisors than men, while men display more of their lower
central incisors than women.
(Aust Orthod J 2010; 26: 27–32)
Received for publication: June 2009
Accepted: November 2009
Andrea Fonseca Jardim da Motta: afjmotta@gmail.com
Margareth Maria Gomes de Souza: margasouzaster@gmail.com
Ana Maria Bolognese: anabolognes@yahoo.com.br
Clarice Júlia Guerra: neycurvo@yahoo.com.br
José Nelson Mucha: nelsonmucha@wnetrj.com.br
Introduction
Facial appearance is an important factor in many cultures and the mouth and teeth in particular are major
factors determining our perceptions of emotion and
facial attractiveness.1–3 In orthodontics, we generally
evaluate dentofacial attractiveness from a lateral view
rather than in a full or three-quarter view of the
face.4–8 The latter two views are widely used by
the media to illustrate and identify faces while the
profile view is generally reserved for postage stamps,
coins and orthodontic publications. It could be
argued that an assessment of facial aesthetics should
begin by viewing the patient from the front, at rest,
© Australian Society of Orthodontists Inc. 2010
during conversation and smiling.8 The extent to which
the anterior teeth are displayed when the lips are at
rest and during activities, such as smiling, may influence our perception of facial attractiveness and should
be part of the initial orthodontic assessment.3,7
Various authors have described a gradual reduction in
the display of the upper central incisors and an
increase in lower incisor display with increasing
age.9–12 The display of lower incisors in individuals
60 years or older was reported to be similar to the display of upper incisors in subjects less than 30 years of
age.9 Furthermore, women tend to show more of
their upper anterior teeth and less of their lower
Australian Orthodontic Journal Volume 26 No. 1 May 2010
27
MOTTA ET AL
Households, conducted by the Brazilian Institute of
Geography and Statistics (IBGE), white Brazilians
make up 53.6 per cent of the metropolitan population. The remainder are: Pardos, a mixture of Whites,
Blacks and Indigenous groups with complexions
varying from light to dark (33.6 per cent); black
Brazilians (12.3 per cent); Asian and/or Indigenous
Brazilians (0.5 per cent).
Figure 1. Measurement of upper central incisor display.
anterior teeth than men.9,11–13 However, Peck et al.
found no significant gender differences in the relationships between the upper lip and the teeth with
the lips at rest.10
Although various authors have suggested guidelines
for the arrangement of the anterior teeth, no author
has reported the extent to which the anterior teeth are
visible in the frontal view in a mixed population,
when the lips are relaxed.9,10,12,15 We aim to determine how much of the upper and lower central
incisor crowns are visible in the white Brazilian subjects with their lips at rest, and to determine if age
and gender influence the findings.
Materials and methods
The subjects in this cross-sectional study were 120
male and 120 female white Brazilians between 12 and
72 years of age. The subjects were divided into the
following age groups: 12 to 15 years of age (Group 1);
20 to 30 years of age (Group 2); 31 to 50 years of age
(Group 3); 51 years of age and older (Group 4). Each
group consisted of 30 males and 30 females randomly selected from three sources. The subjects in
Group 1 were selected from students attending a city
high school and the subjects in Group 2 were selected from dental students attending the Federal
University of Rio de Janeiro. Group 3 and 4 subjects
were selected from patients attending two private
dental clinics. The subjects in all groups were randomly selected from those that met the inclusion criteria using the Statistical Package for the Social
Sciences (SPSS Inc., Chicago, IL, USA).
At the time of examination all subjects lived in Rio de
Janeiro. According to the latest National Survey of
28
Australian Orthodontic Journal Volume 26 No. 1 May 2010
Only white Brazilians with orthognathic profiles, no
facial disharmony, normal occlusion or Angle Class I
malocclusion who would not benefit from any form
of orthodontic treatment were included. Subjects
with a history of facial surgery, anterior dental
trauma, restored upper or lower incisors or previous
orthodontic treatment were excluded.
Measurements of incisor display were obtained with
the lips at rest and mandibular posture unstrained.10,16
The following procedure was used: subjects were
asked to stand in front of the examiner in a natural
upright posture with Frankfort plane parallel to the
floor.16 They were then instructed to wet their lips
with their tongues, open their mouths gently, swallow
and articulate the word ‘Emma’.17 Each subject’s posture was checked twice to ensure that the lips were at
rest and the teeth slightly apart.8
The amounts of upper and lower central incisor
crowns displayed were then measured with a dial
caliper from the midpoints of the incisal edges of
both upper central incisors to the lower border of the
upper lip and from the midpoints of both lower
central incisors to the upper border of the lower lip
(Figure 1).9,12 When measurements of the right and
left central incisors differed, the mean of both incisors
was used, and when an incisor could not be seen the
measurement was considered to be zero.
The entire procedure was performed by a single
examiner and the error of the method was established
by repeating the measurements in 60 subjects, one
week apart. In order to verify the intra-examiner
systematic error, Student’s paired t-tests were applied
and the random error was calculated using Dahlberg’s
formula.18 The results of the error analysis indicated
that the method was reliable because the differences
were not statistically significant and Dahlberg’s formula revealed that the errors ranged from 0.22 to
0.31 mm.
The Kruskal-Wallis non-parametric test was performed to assess differences between the age groups
DISPLAY OF INCISORS AS FUNCTIONS OF AGE AND GENDER
Table I. Upper and lower central incisor display with the lips at rest.
Group
Central
incisors
Gender
Mean
(mm)
SD
(mm)
Median
Minimum
Maximum
Group 1 (12–15 years)
Upper
Female
Male
Female
Male
4.45
3.35
0.47
0.61
1.19
1.14
0.42
0.57
4.62
3.35
0.50
0.66
2.49
1.09
0.00
0.00
6.39
5.57
1.06
1.72
Female
Male
Female
Male
3.57
2.24
0.60
0.97
1.28
1.34
0.66
1.08
3.64
1.89
0.50
0.58
0.69
0.18
0.00
0.00
5.97
5.21
2.66
4.39
Female
Male
Female
Male
2.25
1.73
1.75
1.82
0.87
1.28
1.16
0.93
2.49
1.53
1.56
1.52
0.52
0.00
0.00
0.52
4.32
4.36
4.58
4.01
Female
Male
Female
Male
1.32
0.57
2.22
3.05
1.18
0.53
1.20
1.45
1.24
0.60
2.24
3.12
0.00
0.00
0.00
0.95
3.55
1.94
4.22
5.30
Lower
Group 2 (20–30 years)
Upper
Lower
Group 3 (31–50 years)
Upper
Lower
Group 4 (≥ 51 years)
Upper
Lower
and genders, and when a significant difference was
found the Mann-Whitney U test was used. Probabilities < 0.05 were considered to be statistically significant.
Results
The results indicate that the display of the upper
incisors declined with age in both genders, and that
male Brazilians showed less of their upper incisors
than female Brazilians (Table I). In both genders
there was a gradual increase in lower incisor display
with age.
In the youngest female subjects (Group 1) 4.45 ±
1.19 mm of the upper incisor crowns were visible
below the upper lip and in the youngest male subjects
3.35 ± 1.14 mm of the upper incisor crowns were visible. The lengths of the upper central incisors crowns
visible below the upper lips in the females fell steadily
with increasing age from 3.37 ± 1.28 mm (Group 2),
to 2.25 ± 0.87 mm (Group 3) to 1.32 ± 1.18 mm
(Group 4). The lengths of the upper incisors crowns
visible below the upper lips in the males fell at a
similar rate from 3.35 ± 1.14 mm in Group 1 to 0.57
± 0.53 mm in Group 4 (Figure 2).
In the female subjects, the lengths of lower central
incisors displayed at rest increased from a mean
of 0.47 mm in Group 1, to 0.60 mm in Group 2,
1.75 mm in Group 3 and 2.22 mm in Group 4. The
increase was greater in the male subjects than in the
female subjects: 0.61 mm in Group 1, 0.97 mm in
Group 2, 1.82 mm in Group 3 and 3.05 mm in
Group 4 (Figure 3).
Table II gives gender comparisons of the upper and
lower incisor display for the different age groups. In
all age groups, the female subjects displayed more of
the upper central incisors than the male subjects, and
the males showed more of their lower incisor crowns
than the female subjects. The male – female differences for upper incisor display reached statistical significance in Groups 1, 2 and 4 and for lower incisor
display in Group 4 (Table II).
Comparisons of incisor display in the various groups
and for both genders are given in Table III. In the
female subjects, the decrease in upper incisor display
was significant when all groups were compared with
each other, but there were no significant differences
in lower incisor display in Groups 1 and 2, and
Groups 3 and 4. In males, the display of upper incisors fell significantly in all groups, except between
Groups 2 and 3. The age-related increase in the display of lower incisors in the men was not significant
when comparing Groups 1 and 2, but it was significant for the other groups.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
29
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
4.45
3.5
3.45
3.57
2.5
2.24
2.25
1.73
Female
Male
1.32
0.57
Group 1
12 to 15
years
Group 2
20 to 30
years
Group 3
31 to 50
50 years
2.22
2
1.75
1.82
1.5
Female
Male
0.97
1
0.5
0.47
0.61
0.6
0
Group 4
50 years
or more
Group 1
12 to 15
years
Group 2
20 to 30
years
Group 3
31 to 50
50 years
Group 4
50 years
or more
Figure 2. Mean values (mm) for the display of upper incisors, by age and
gender.
Figure 3. Mean values (mm) for the display of lower incisors, by age and
gender.
Table II. Gender comparisons of upper and lower incisor display.
country with five geographical regions and several
large cities. As can be seen from the data provided by
the IBGE (the agency responsible for statistical, geographic, cartographic, geodetic and environmental
information in Brazil) the country’s population is
diverse, comprising many races and ethnic groups. So
it is possible that white Brazilians from Southern
Brazil may differ from white Brazilians in the North
of the country. However, the results obtained in this
study confirm what others have reported on upper
and lower incisor display.
Group
Central
incisors
Group 1
(12–15 years)
Group 2
20–30 years)
Group 3
(31–50 years)
Group 4
(≥ 51 years)
Upper
Lower
Upper
Lower
Upper
Lower
Upper
Lower
Median (mm)
Females Males
4.62
0.50
3.64
0.50
2.49
1.56
1.24
2.24
3.35
0.66
1.89
0.58
1.53
1.52
0.60
3.12
U*
p
235.0
363.5
205.0
372.5
334.0
426.0
282.5
312.5
< 0.01
> 0.05
< 0.01
> 0.05
> 0.05
> 0.05
< 0.05
< 0.05
* Mann-Whitney U test, significant values in bold
Discussion
We measured the upper and lower incisor crowns visible below and above the margins of the lips in white
Brazilians living in Rio de Janeiro. When the lips were
at rest, we found the upper incisor display reduced
with age and the lower incisor display increased in
women and men. As a rule, the women showed more
of their upper incisors than the men, while the men
displayed more of their lower incisors than the
women. These findings may have important implications for orthodontic treatment planning, which
tends to ignore long-term changes in the incisor – lip
relationships.
One aspect that must be considered is that the
sample selected for this study may not be representative of all white Brazilians since the research was
held in the city of Rio de Janeiro and Brazil is a large
30
3.05
3
mm
mm
MOTTA ET AL
Australian Orthodontic Journal Volume 26 No. 1 May 2010
The display of the anterior teeth is relevant not only
for dental aesthetics, but also for facial attractiveness.
The shape, alignment, position and display of
the upper central incisors determine a pleasant
smile and should be considered when planning
orthodontic treatment.20 One of the challenges an
orthodontist or restorative dentist may face is
to determine the extent to which damaged upper
incisors should be displayed. In such situations, the
relationship between the upper lip and the displayed
portion of the anterior teeth at rest is an important
consideration.5–8,10,12,21
We selected subjects with a normal or Angle’s Class I
malocclusion. Subjects with the latter condition had
slightly misaligned teeth, but it was not severe
enough to require orthodontic treatment. Although
the subjects we selected may not be representative of
the patients seeking orthodontic treatment, our
average values can be used as reference points or
guidelines for incisor display, particularly for smile
aesthetics in the long-term.
DISPLAY OF INCISORS AS FUNCTIONS OF AGE AND GENDER
Table III. Age comparisons of upper and lower central incisor display.
Females
Group 2
Males
Group 3
Group 4
Group 2
Group 3
Group 4
Upper central incisors
Group 1
238.0 (<0.05)
Group 2
Group 3
-
56.5 (<0.01)
183.0 (<0.01)
-
33.5 (<0.01)
91.0 (<0.01)
249.0 (<0.01)
224.0 (<0.01)
-
159.5 (<0.01)
355.0 (>0.05)
-
8.5 (<0.01)
83.5 (<0.01)
205.0 (<0.01)
Lower central incisors
Group 1
427.5 (>0.05)
Group 2
Group 3
-
117.0 (<0.01)
159.5 (<0.01)
-
98.5 (<0.01)
124.5 (<0.01)
334.5 (>0.05)
378.5 (>0.05)
-
129.0 (<0.01)
222.0 (<0.01)
-
56.0 (<0.01)
117.5 (<0.01)
228.0 (<0.01)
Mann-Whitney U test, p values in brackets, significant values in bold
Some authors consider that the smile is the main aesthetic factor in an orthodontic diagnosis.12–24 Useful
information can be obtained by observing a patient
during normal conversation, but care should be exercised when observing the upper lip as it moves
from the rest position to a full smile as the final
position can be highly variable.8 The positions of
the incisal edges of the upper incisors relative to the
relaxed lips are often used in orthodontic treatment planning as a vertical reference point. The
determination of the ‘relaxed lips position’ is reproducible, but not easily obtained for all patients or on
some occasions.21
Our findings on the age changes in the display of
the upper and lower incisors and, in particular, the
reduced display of the upper anterior teeth and
increased display of lower anterior teeth with age,
agree with previous studies.9–12 These results confirm
previous reports that young people display more of
their upper incisors than older people.5,14 These
changes were not determined by changes in the positions of the teeth, but rather by age-related changes in
the facial tissues and the effect of gravity on the lips.25
Elongation of the lips continues throughout life and
exceeds the age-related increase in lower anterior face
height.19 The positions of the lips also depend on
factors such as lip length, lip type and muscle tonus,
but we did not assess these factors.
Age-related changes in incisor display can be underestimated if the sample includes subjects from a
narrow age band.10 We used subjects between 12 and
72 years, but only the gender comparisons between
Groups 1, 2 and 4 were statistically different. It is
important that incisor display is appropriate for the
age of the patient. The prosthodontic literature
typically recommends that artificial teeth are set up so
that 2 mm of the central incisor crowns are visible
when the lips are at rest, but patients who want a
more youthful appearance will often ask for more of
their incisor crowns to be visible.14 When the display
of the anterior teeth is considered insufficient (e.g.
excessive tooth wear) the patient’s age can be used as
a reference to determine the average length of incisors
visible at rest. In orthodontic treatment planning the
mean values can be used to establish the amount of
intrusion to be performed in the upper and/or lower
arches. Over-intrusion of the upper incisors in young
patients may result in aesthetically compromised
smiles later in life.8,26 Some authors have recommended that the lower incisors rather than the
upper incisors should be intruded to preserve smile
aesthetics as the patient ages.8,22,23
Routine use of incisal edge – lip border measurements
taken with the lips at rest should be an important part
of a diagnosis and subsequent treatment planning, not
only in orthodontics but also in other fields of dentistry.
We have provided data on the appropriate positions
of the incisors to optimise dentofacial aesthetics in a wide
age range of patients. Additional studies are needed, however, to determine how a smile may change with age.
Conclusions
1. With increasing age, both genders show less of
their upper incisors and more of their lower incisors.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
31
MOTTA ET AL
2. Females display more of their upper incisors than
males and males display more of their lower incisors
than females.
Corresponding author
Dr Andrea Fonseca Jardim da Motta
Ave. Engenheiro Martins Romeu n.41, apt.803
Ingá, Niterói, RJ
Brazil CEP 24210-400
Email: afjmotta@gmail.com
References
1.
Kershaw S, Newton JT, Williams DM. The influence of
tooth colour on the perceptions of personal characteristics
among female dental patients: comparisons of unmodified,
decayed and ‘whitened’ teeth. Br Dent J 2008;204:pE9.
2. Eli I, Bar-Tal Y, Kostovetzki I. At first glance: social meanings of dental appearance. J Public Health Dent 2001;61:
150–4.
3. Mack MR. Perspective of facial esthetics in dental treatment
planning. J Prosthet Dent 1996;75:169–76.
4. Hulsey CM. An esthetic evaluation of lip-teeth relationships
present in the smile. Am J Orthod 1970;57:132–44.
5. Miller CJ. The smile line as a guide to anterior esthetics.
Dent Clin North Am 1989;33:157–64.
6. Mackley RJ. ‘Animated’ orthodontic treatment planning. J
Clin Orthod 1993;27:361–5.
7. Sarver DM, Ackerman JL. Orthodontics about face: The reemergence of the aesthetic paradigm. Am J Orthod
Dentofacial Orthop 2000;117:575–6.
8. Zachrisson BU. Esthetic factors involved in anterior tooth
display and the smile: vertical dimension. J Clin Orthod
1998;32:432–45.
9. Vig RG, Brundo GC. The kinetics of anterior tooth display.
J Prosthet Dent 1978;39:502–4.
10. Peck S, Peck L, Kataja M. Some vertical lineaments of lip
position. Am J Orthod Dentofacial Orthop 1992;101:
519–24.
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Australian Orthodontic Journal Volume 26 No. 1 May 2010
11. Dickens ST, Sarver DM, Proffit WR. Changes in frontal soft
tissue dimensions of the lower face by age and gender. World
J Orthod 2002;3:312–20.
12. Al Wazzan KA. The visible portion of anterior teeth at rest.
J Contemp Dent Pract 2004;5:53–62.
13. Arnett GW, Bergman RT. Facial keys to orthodontic diagnosis and treatment planning. Part II. Am J Orthod
Dentofacial Orthop 1993;103:395–411.
14. McLaren EA, Rifkin R. Macroesthetics: facial and dentofacial analysis. J Calif Dent Assoc 2002;30:839–46.
15. Misch CE. Guidelines for maxillary incisal edge position-a
pilot study: the key is the canine. J Prosthodont 2008;17:
130–4.
16. Burstone CJ. Lip posture and its significance in treatment
planning. Am J Orthod 1967;53:262–84.
17. Zachrisson BU. Facial esthetics: guide to tooth positioning
and maxillary incisor display. World J Orthod 2007;8:
308–14.
18. Houston WJ. The analysis of errors in orthodontic measurements. Am J Orthod 1983;83:382–90.
19. Vig PS, Cohen AM. Vertical growth of the lips: a serial
cephalometric study. Am J Orthod 1979;75:405–15.
20. Spear FM, Kokich VG, Mathews DP. Interdisciplinary management of anterior dental esthetics. J Am Dent Assoc 2006;
137:160–9.
21. Burstone CJ. Charles J. Burstone, DDS, MS. Part 1. Facial
esthetics. Interview by Ravindra Nanda. J Clin Orthod
2007;41:79–87.
22. Sarver DM. The importance of incisor positioning in the
esthetic smile: the smile arc. Am J Orthod Dentofacial
Orthop 2001;120:98–111.
23. Sarver DM, Ackerman MB. Dynamic smile visualization and
quantification: Part 1. Evolution of the concept and dynamic records for smile capture. Am J Orthod Dentofacial
Orthop 2003;124:4–12.
24. Lindauer SJ, Lewis SM, Shroff B. Overbite Correction and
Smile Aesthetics. Semin Orthod 2005;11:62–6.
25. Fudalej P. Long-term changes of the upper lip position
relative to the incisal edge. Am J Orthod Dentofacial
Orthop 2008;133:204–9.
26. Ackerman MB, Ackerman JL. Smile analysis and design in
the digital era. J Clin Orthod 2002;36:221–36.
McNamara norms for Turkish adolescents with
balanced faces and normal occlusion
Nihat Kilic, Gülhan Catal and Hüsamettin Oktay
Department of Orthodontics, Faculty of Dentistry, Atatürk University, Erzurum, Turkey
Background: There are no norms for the McNamara analysis for Turkish adolescents.
Objective: To obtain cephalometric standards for the McNamara analysis for Turkish adolescents with balanced faces and
Class I occlusions, and to compare the standards with published data.
Methods: The cephalometric radiographs of 116 children (83 female, 33 male) between 11 and 16 years of age with Turkish
grandparents and Class I occlusion, well-aligned upper and lower dental arches, no anterior and/or posterior crossbites and
normal dentofacial structures were used. The eight linear and two angular measurements in the McNamara analysis were measured on images of the scanned radiographs. Measurements of the male and female subjects were compared with each other
and with published norms for North American adolescents and adults.
Results: The Co-Gn, Co-A, ANS-Me and Ui-A were larger in the male subjects. Comparisons between the present study and
McNamara’s original study revealed that Anatolian Turkish adolescents, particularly girls, have smaller midfacial and mandibular lengths and longer and more retrusive faces than North American adolescents and adults.
Conclusions: The small, but statistically significant, gender differences in mandibular and midfacial lengths and lower anterior
face height may not be clinically significant. A single set of Turkish norms for the McNamara analysis may be appropriate.
(Aust Orthod J 2010; 26: 33–37)
Received for publication: January 2009
Accepted: November 2009
Nihat Kilic: drnkilic@yahoo.com
Gülhan Catal: drgulhancatal@yahoo.com
Hüsamettin Oktay: hoktay@atauni.edu.tr
Introduction
Cephalometric analysis is an important part of orthodontic diagnosis and treatment planning. It provides
information on the relationships of the facial bones
and teeth not easily obtained by physical examination. The usual method is to compare a variable in
an individual with the same variable in an agematched, representative sample. The information
gained can be used in communication with other
professionals and with patients. Some specialised
analyses have been designed to compare different
ethnic/racial or family groups, but the McNamara
analysis, which is the subject of this communication,
is a clinical analysis composed of eight linear and two
angular measurements.1 This analysis describes the
relative positions of the maxillae and mandible,
the length of the mandible, the height of the face and
© Australian Society of Orthodontists Inc. 2010
the positions of the incisors. It has several limitations,
such as reliance on linear measurements, which are
influenced by magnification and may differ from
cephalostat to cephalostat, the use of unfamiliar
measurements to describe the positions of the incisors
and no soft tissue measurements. In spite of these disadvantages we have found that the measurements in
the analysis give a useful appraisal of dentofacial
relationships, particularly for the age group likely to
require orthopaedic treatment.
As no norms for Turkish adolescents exist for the
McNamara analysis and eight out of 10 of the
measurements in this analysis are affected by magnification, we decided to obtain norms for Turkish
adolescents with well-balanced faces and Class I
occlusions, and to determine if there are gender
differences in the measurements.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
33
KILIC ET AL
Materials and methods
This study was approved by the Ethics Committee
Board of the School of Dentistry, Atatürk University.
The material consisted of the lateral cephalometric
films of 116 (83 female, 33 male) 11 to 16 year-old
Turkish adolescents with Turkish grandparents,
selected from the longitudinal archive in the
Department of Orthodontics, Faculty of Dentistry,
Atatürk University. The mean ages of the girls and
boys were 13.42 ± 1.13 years and 13.65 ± 1.47 years,
respectively. The subjects had a Class I molar
relationship, well-aligned upper and lower dental
arches with no/little crowding, no anterior and/or
posterior crossbites and normal dental development.
The radiographs of subjects with a history of previous
orthodontic treatment, facial and/or dental trauma,
systemic disease, subjective neuromuscular symptoms,
symptoms of TMD, developmental and/or acquired
craniofacial or neuromuscular deformities were
excluded.
Figure 1. The landmarks and measurements used in McNamara
cephalometric analysis.1
1. A-N perpendicular (mm)
2. Effective mandibular length (Co-Gn, mm)
3. Effective midfacial length (Co-A, mm)
4. Maxillo-mandibular difference (Mx-Md difference, mm)
5. Lower anterior facial height (ANS-Me, mm)
6. Mandibular plane angle (FH/MP, degrees)
7. Facial axis angle (90˚ minus NBa-PtmGn, degrees)
8. Pog-N perpendicular (mm)
9. Ui-A (mm)
10. Li-APog (mm)
All radiographs were taken with the Frankfort plane
parallel to the floor, the teeth in centric occlusion and
the lips at rest. The image enlargement was 8.7 per
cent and the data were not corrected for this enlarge-
Table I. McNamara cephalometric norms for 11-16 year-old Turkish children.
Variable
1.
A-N perpendicular (mm)
Female
Male
2. Effective mandibular length (Co-Gn) (mm)
Female
Male
3. Effective Midfacial length (Co-A) (mm)
Female
Male
4. Maxillo-mandibular difference
Female
(Mx-Md diff) (mm)
Male
5. Lower anterior facial height
Female
(ANS-Me) (mm)
Male
6. Mandibular plane angle (FH/MP) (degrees) Female
Male
7. Facial axis angle (90˚minus
Female
NBa-PtmGn) (degrees)
Male
8. Pog-N perpendicular (mm)
Female
Male
9. Ui-A (mm)
Female
Male
10. Li-APog (mm)
Female
Male
Significant values in bold
34
Australian Orthodontic Journal Volume 26 No. 1 May 2010
Mean
SD
Minimum
Maximum
p
-0.44
0.18
113.65
117.36
88.65
91.39
24.86
25.97
66.66
69.43
25.01
25.02
-1.93
-2.34
-4.79
-3.92
3.15
4.19
1.67
2.48
2.52
2.36
5.64
6.24
4.13
4.73
3.39
3.87
4.16
4.84
3.65
3.22
3.89
3.38
4.55
4.29
2.15
2.22
2.28
1.92
-6.20
-3.50
95.40
106.90
79.20
82.20
13.30
18.70
56.60
59.10
16.40
17.90
-11.60
-9.80
-15.50
-13.10
-3.70
0.50
-3.70
-0.50
5.50
5.30
133.00
133.40
99.00
103.90
32.70
32.80
76.10
79.60
33.30
32.70
9.90
4.60
4.90
3.70
6.70
10.90
6.90
7.00
0.226
0.002
0.002
0.127
0.003
0.983
0.594
0.342
0.022
0.073
MCNAMARA NORMS FOR TURKISH ADOLESCENTS
Table II. Comparisons of the means with published norms.
Parameters
1.
A-N perpendicular (mm)
Female
Male
2. Effective mandibular length (Co-Gn) (mm)
Female
Male
3. Effective midfacial length (Co-A) (mm)
Female
Male
4. Maxillo-mandibular difference (Mx-Md diff) (mm)
Female
Male
5. Lower anterior facial height (ANS-Me) (mm)
Female
Male
6. Mandibular plane angle (FH-MP) (degrees)
Female
Male
7. Facial axis angle (90˚ minus NBa-PtmGn) (degrees) Female
Male
8. Pog-N perpendicular (mm)
Female
Male
9. Ui-A (mm)
Female
Male
10. Li-APog (mm)
Female
Male
Present
study
Bolton
(14 years)1
-0.44 a
0.18
113.65 c
117.36
88.65 a,c
91.39 b1,b2
24.86
25.97
66.66
69.43
25.01 c
25.02 c
-1.93 c
-2.34 c
-4.79 c
-3.92 c
-3.15
-4.19
-1.67
-2.48
Burlington
(14 years)1
Ann Arbor
(Adults)1
-0.4 a
-1.1
118.9 c
120.6
92.1 c
95.2 b1
26.7
25.3
65.6
66.8
114.9
119.2
89.2 a
93.9 b2
25.7
25.3
66.2
68.8
-22.7
-21.3
-0.2
-0.5
-1.8
-0.3
c
c
c
c
c
c
4.2
3.8
1.4
1.4
a, p < 0.05; b, p < 0.01; c, p < 0.001
Image enlargement: present study 8.7 per cent; McNamara’s study 8.0 per cent
ment. The films were scanned with an Epson
Expression 1860 Pro scanner (Seiko Epson
Corporation, Japan) and the resulting images (100
per cent) were digitised and measured using Quick
Ceph 2000 (Quick Ceph Systems, San Diego, CA,
USA). The landmarks and measurements in
McNamara analysis are shown in Figure 1.1
Statistical analysis
To determine the measurement errors, 15 randomly
selected radiographs were remeasured by the same
examiner two weeks after the initial measurements.
The reliability of the measurements was assessed with
intra-class correlation coefficients.2 Student’s t-tests
were used to compare the measurements in the boys
and girls, and to compare the measurements in the
Turkish boys and girls with the norms published by
McNamara.1 All statistical analyses were performed
using the SPSS software package (SPSS for Windows
98, version 10.0, SPSS Inc., Chicago, IL, USA).
Results
The reliability coefficients exceeded 0.90 for all
measurements, indicating that the measurements
could be reliably repeated.
Comparisons of the measurements in the girls and
boys are given in Table I. The effective mandibular
length (Co-Gn), effective midfacial length (Co-A),
lower anterior facial height (ANS-Me) and the distance from the labial surface of the most prominent
upper central incisor to the perpendicular to the
Frankfort line through A point (Ui-A) were significantly larger in the boys. The lower incisors in the
boys were almost 1 mm further behind the A-Pog line
than the lower incisors in the girls, but the difference
was not statistically significant (p = 0.073).
The means of the female and male Turkish adolescents were compared with the 14 year-old adolescents
in the Bolton and Burlington studies and the adults
in the Ann Arbor study reported by McNamara
(Table II).1 The Turkish girls had significantly more
Australian Orthodontic Journal Volume 26 No. 1 May 2010
35
KILIC ET AL
retruded maxillae (A-N perp, p < 0.05) than the Ann
Arbor adults, and significantly shorter mandibles
(Co-Gn, p = 0.001) than the 14 year-old American
girls in the Bolton study, but not the Canadian girls
in the Burlington study. The midfacial lengths
(Co-A) in the Turkish girls and boys were shorter
than the same lengths in the adolescents in the Bolton
and Burlington studies. The Turkish adolescents also
had significantly steeper mandibular plane angles
(FH/MP) than the Ann Arbor adults (Females,
p < 0.001; Males, p < 0.001). The facial axis angle
(90º minus NBa-PtmGn), the angle between the
nasion-basion line and the constructed line from the
postero-superior aspect of the pterygomaxillary fissue
to gnathion subtracted from 90 degrees, was significantly less in Turkish adolescents compared with the
adolescents in the Ann Arbor study (Females,
p < 0.001; Males, p < 0.001). The mandibles (Pog-N
perp) in the Turkish adolescents were also 3 to 3.5
mm more retruded than the mandibles in the Ann
Arbor adults. There were no significant differences
between the positions of the upper and lower incisors
(Ui-A distance, Li-APog distance) in the Turkish
adolescents and the samples reported by McNamara.1
Discussion
We used the lateral cephalometric radiographs of
Turkish adolescents with well-balanced faces to establish clinical norms for the McNamara analysis. This
analysis uses relatively few measurements to describe
the dental and skeletal relationships of interest to
orthodontists and maxillofacial surgeons. We found
that the girls in our sample had slightly shorter midfacial (Co-A) and mandibular lengths (Co-Gn) and
shorter lower anterior face heights (ANS-Me) than
the boys in our sample. The differences were small,
ranging from slightly over 1 mm in the case of Ui-A
to almost 4 mm in the case of Co-Gn and very variable. Because different ethnic groups can have different morphological features we wanted our sample to
be representative of the children we treat. Therefore,
we chose adolescents with Class I occlusions and
Turkish grandparents attending our clinic for treatment and in the same age group as the majority of
our patients. Besides sharing a common culture and
language, individuals in an ethnic group often have a
similar dentofacial morphology that sets them apart
from other groups.3 However, many countries such as
Turkey contain several different ethnic groups and
separate norms may be required for each group.
36
Australian Orthodontic Journal Volume 26 No. 1 May 2010
We were primarily interested in providing norms for
the McNamara analysis, which appraises dentofacial
skeletal relationships. We selected individuals with
close-to-ideal occlusal relationships and no visible
dentoskeletal anomalies because we wanted to use the
norms for orthodontic diagnosis and treatment planning for patients attending our clinic. Unlike many
other orthodontic analyses the McNamara analysis
relates the maxillae, mandible and incisors to vertical
facial planes: the principal one is the perpendicular
line to the Frankfort plane passing through nasion.
Although this analysis avoids some of the problems
associated with more widely used ANB angle for
determining skeletal relationships, it relies on linear
measurements that may vary with age and with the
cephalostat used. The SNA angle increases approximately 1 degree from 6 to 18 years of age, and a
1 degree change at point A is equivalent to a 1 mm
linear change in the position of point A relative to
nasion.4 Furthermore, analyses that have linear measurements are not popular because separate norms or
correction factors are required for cephalostats with
different image enlargements. However, we were fortunate that the image magnification of our cephalostat was 8.7 per cent, which closely matches the 8 per
cent image enlargement in McNamara’s study.1
Previous studies have reported significant differences
in the dentofacial relationships of Turkish and nonTurkish children.5–7 We found that the midfaces of
the Turkish girls were slightly less protrusive than the
North American adults reported by McNamara, and
that the girls and boys in our sample had slightly
longer faces (FH/MP, 90º minus NBa-PtmGN, PogN perp) than the North American adults.1 These differences may be due to growth and/or maturational
changes in the North American sample or methodological differences.8 In contrast to our findings,
Bassciftci et al., who also used the McNamara analysis,
reported there were no significant differences in the
A-N perpendicular distance, effective mandibular
and midfacial lengths between his sample of Turkish
adults and North American adults.1,8 Gazilerli6 and
Ceylan and Gazilerli7 also reported that Turkish children had retrusive faces compared with American
children.
Generally boys have larger dentofacial measurements
than girls, although the differences may not be clinically significant. The concept of clinical significance
in cephalometric studies has yet to become widely
MCNAMARA NORMS FOR TURKISH ADOLESCENTS
adopted. We found the mean gender differences for
Co-A, Co-Gn and ANS-Me were around 3–4 mm. In
agreement with Ioi et al.,9 Basciftci et al.8 and
Swlerenga et al.10 we found that the mandibular
length (Co-Gn), midfacial length (Co-A) and lower
anterior face height (ANS-Me) were significantly
larger in the boys. Our differences ranged from 2.74
mm for Co-A to 3.71 mm for Co-Gn. On the other
hand, Wu et al.,11 who also used the McNamara
analysis, reported that only midfacial length and
lower anterior facial height were larger in male
Chinese subjects. Ioi et al.9 reported that measurements of Pog-N perpendicular in Japanese and
Caucasian males were -6.8 mm and -0.3 mm, respectively; and the effective mandibular lengths (Co-Gn)
were 130.40 mm and 134.3 mm, respectively. The
differences were statistically significant, indicating
that Japanese have more retruded facial profiles than
Caucasians.
Conclusions
The small, but statistically significant, gender
differences in mandibular and midfacial lengths,
lower anterior face height and upper incisor protrusion may not be clinically significant. A single set of
Turkish norms for the McNamara analysis may be
appropriate.
Corresponding author
References
1.
McNamara Jr JA. A method of cephalometric evaluation.
Am J Orthod 1984;86:449–69.
2. Houston WJ. The analysis of errors in orthodontic measurements. Am J Orthod 1983;83:382–90.
3. Richardson ER. Racial differences in dimensional traits of
the human face. Angle Orthod 1980;50:301–11.
4. Riolo ML, Moyers RE, McNamara JA, Hunter WS. An atlas
of craniofacial growth: cephalometric standards from the
University School growth study. Monograph No. 2,
Craniofacial Growth Series, Center for Human Growth and
Development, University of Michigan, Ann Arbor. 1974;
23–373.
5. Gulyurt M. Ricketts' frontal cephalometric measurements in
the children of Erzurum region. Türk Ortodonti Derg
1989;2:144–51.
6. Gazilerli Ü. (Thesis) Seiner norms of Ankara Children with
normal occlusion aged between 13–16 years. Ankara
University, Faculty of Dentistry, Department of Dentomaxillo-facial Orthopedics. Ankara, 1976.
7. Ceylan I, Gazilerli Ü. A comparison of Steiner, Downs and
Tweed measurements of the children living Erzurum area
with other some groups. J Dental Faculty Ankara University.
1992;19:143–52.
8. Basciftci FA, Uysal T, Buyukerkmen A. Craniofacial structure of Anatolian Turkish adults with normal occlusions and
well-balanced faces. Am J Orthod Dentofacial Orthop 2004;
125:366–72.
9. Ioi H, Nakata S, Nakasima A, Counts AL. Comparison of
cephalometric norms between Japanese and Caucasian adults
in antero-posterior and vertical dimension. Eur J Orthod
2007;29:493–9.
10. Swlerenga D, Oesterle LJ, Messersmith ML. Cephalometric
values for adult Mexican-Americans. Am J Orthod
Dentofacial Orthop 1994;106:146–55.
11. Wu J, Hägg U, Rabie AB. Chinese norms of McNamara's
cephalometric analysis. Angle Orthod 2007;77:12–20.
Dr Nihat Kilic
Atatürk Üniversitesi Diş Hekimliği Fakültesi
Ortodonti Anabilim Dalı
25240 Erzurum
Turkey
Email: drnkilic@yahoo.com
Tel: +90 442 2311810
Fax: +90 442 2312270 - 2360945
Australian Orthodontic Journal Volume 26 No. 1 May 2010
37
Assessment of slot sizes in self-ligating brackets
using electron microscopy
Nidhi B. Bhalla, * Sarah A. Good, + Fraser McDonald, * Martyn Sherriff †
and Alex C. Cash ±
Department of Orthodontics, King’s College Hospital;* ‘Guys and St Thomas’ NHS Foundation Trust, London,+ Department of Biomaterials,
King’s College London Dental Institute† and the Queen Victoria Hospital, East Grinstead,± United Kingdom
Objective: To measure the slot dimensions of 0.022 inch self-ligating upper central incisor brackets from six manufacturers using
electron microscopy, to compare the measured dimensions with the manufacturers’ published dimensions, and to determine if
the walls of the slots were parallel.
Materials: Six self-ligating upper central incisor brackets from four manufacturers (SmartClip and Clarity SL, 3M Unitek,
Monrovia, CA, USA; Speed, Strite Industries Ontario, Canada; Damon MX, Ormco, Orange, CA, USA; In-Ovation R and
In-Ovation C, Dentsply GAC, Bohemia NY, USA) were imaged with a scanning electron microscope and the slots heights
measured. Intra-operator repeatability and accuracy were determined.
Results: All brackets had slot sizes that were significantly larger (p < 0.05) than the stated 0.022 inch. Speed brackets were
5.1 per cent larger (0.02311 inch) and the closest to the published dimension. The SmartClip brackets were 14.8 per cent
larger (0.02526 inch) than the quoted slot size of 0.022 inch. In most brackets the distances between the slot walls was
generally greater further from the bracket bases.
Conclusions: The actual measurements of upper central incisor self-ligating brackets from six manufacturers were larger than the
manufacturers’ stated dimension, and the walls of the slots diverged from the bracket bases.
(Aust Orthod J 2010; 26: 38–41)
Received for publication: March 2009
Accepted: November 2009
Nidha Bhalla: nbbhalla@hotmail.com
Sarah Good: sarah.good@gstt.nhs.uk
Fraser McDonald: fraser.mcdonald@kcl.ac.uk
Martyn Sherriff: martyn.sherriff@kcl.ac.uk
Alex Cash: alex.cash@qvh.nhs.uk
Introduction
Pre-adjusted self-ligating edgewise orthodontic brackets are claimed to be accurately manufactured to each
manufacturer’s prescription, allowing a tooth to be
moved predictably in three dimensions. There has
long been an assumption that the quoted dimensions
of bracket slots are indeed accurate. In fact, several
studies have shown discrepancies between the published and actual dimensions of orthodontic brackets.1–3
The importance of accurately published dimensions
of bracket slots was underlined by Kusy and Whitley.4
They emphasised that clinicians should be aware of
the exact dimensions so that the critical contact angle
for binding can be calculated. This angle is thought to
be important for the efficient treatment of patients, as
38
Australian Orthodontic Journal Volume 26 No. 1 May 2010
binding and the resistance to sliding mechanics can
occur if the contact angle between the archwire and
bracket increases, but it can be somewhat compensated for by the use of slightly oversized brackets and
undersized archwires.
The aims of this study were to measure the slot
dimensions of 0.022 inch self-ligating upper central
incisor brackets from six manufacturers, to compare
the measured dimensions with the manufacturers’
published dimension of 0.022 inch, and to determine
if the walls of the slots were parallel.
Materials and method
Five randomly selected, upper left central incisor
0.022 x 0.028 inch self-ligating brackets from the
© Australian Society of Orthodontists Inc. 2010
ASSESSMENT OF SLOT SIZES IN SELF-LIGATING BRACKETS USING ELECTRON MICROSCOPY
Figure 1. Speed bracket (Original magnification x100).
Figure 2. In-Ovation R bracket (Original magnification x100).
following manufacturers were used: SmartClip and
Clarity SL (3M Unitek, Monrovia, CA, USA); Speed
(Strite Industries Ontario, Canada) (Figure 1);
Damon MX (Ormco, Orange, CA, USA); InOvation R (Figure 2) and In-Ovation C (Dentsply
GAC, Bohemia, NY, USA).
Student’s t-test was used to compare the slot heights.
The method errors were determined using a standard
calibration chart prior to measurements being taken,
and the measurements were repeated two weeks later.
The successive measurements were accurate and
repeatable to greater than 99 per cent.
The brackets were mounted on electron microscope
stubs with conductive putty with the self-ligating
spring or clip either fully open or removed to provide
a clear view of the slot walls. They were orientated on
the stubs so that the mesio-distal axes of the bracket
slots were perpendicular to the bases of the stubs and
the microscope table. The putty allowed the brackets
to be manipulated in the electron microscope to
ensure that the edges of the slots could be imaged.
Non-metallic brackets were sputter-coated with gold
to a thickness no greater than 20 nm in order to allow
accurate scanning and measurement.
Each bracket was scanned individually in the scanning electron microscope (Hitachi S-3500N High
Technologies Corporation, Berkshire, UK) to produce an image from which digital measurements
could be taken. Images were captured, saved as TIFF
Images and exported to Quartz PCI 5.1 (Quartz
Imaging Corporation, Vancouver, Canada). The distances or heights between the walls of the slots were
measured on x100 images and compared to the
dimensions published by each manufacturer.
Data were analysed using the statistical package Stata
10.0 (StataCorp 2003, College Station, TX, USA).
Significance was predetermined at a level of α = 0.05.
Results
The results are given in Tables I and II.
The mean slot heights ranged from 0.02311 inch for
the Speed brackets to 0.02526 inch for the Smartclip
brackets (Table I). Smartclip brackets were the most
variable in slot size (SD: 0.00073 inch) and InOvation R brackets the most consistent in size (SD:
0.00021 inch). The discrepancies ranged from 5.1
per cent for the Speed brackets to 14.8 per cent for
the SmartClip brackets (Table II).
All brackets were statistically significantly larger
than 0.022 inch and most brackets had divergent
slot walls: the distance between the slot walls was
generally greater further from the bracket base.
Discussion
Although the results of this study agree with previous
studies of the slot sizes of conventional brackets, our
use of electron microscopy has enabled a high degree
of accuracy of measurement. We found the slot sizes
of self-ligating brackets to be significantly larger than
the manufacturers’ quoted size of 0.022 inch and the
slot walls to diverge from the base of the slot. The
Australian Orthodontic Journal Volume 26 No. 1 May 2010
39
BHALLA ET AL
Table I. The measured slot heights of self-ligating brackets, in inches.
Bracket
Mean (Inch)
SD (Inch)
Minimum
Maximum
p
In-Ovation R
SmartClip
Speed
Damon MX
Clarity SL
In-Ovation C
0.02385
0.02526
0.02311
0.02478
0.02409
0.02450
0.00021
0.00073
0.00026
0.00033
0.00043
0.00060
0.02362
0.02390
0.02260
0.02429
0.02331
0.02362
0.02417
0.02626
0.02358
0.02516
0.02472
0.02547
0.001
0.001
0.001
0.001
0.001
0.001
Significant values in bold
Probability associated with the t - test for slot height = 0.022 inch
Table II. Percentage differences between the measured bracket heights
and quoted height of 0.022 inch.
Per cent > 0.022 inch
Speed
In-Ovation R
Clarity SL
In-Ovation C
Damon MX
SmartClip
5.1
8.4
9.5
11.4
12.6
14.8
slots in brackets from the same manufacturer may
vary in size as well.2,3
Manufacturing and material parameters affect the
amount of play in the torque dimension.2 FischerBrandies et al. measured five commercially available
archwires and brackets with computer-aided light
microscopy and reported that although the brackets
were on average 0.8 per cent larger than the dimensions quoted by the manufacturers, the archwires had
significantly smaller cross-sections.2 The slot –
archwire difference was thought to be a major contributor to torque play. This rather large discrepancy,
as compared to the findings of our study, may be a
function of the relative accuracy of the two measurement techniques or, indeed, the different brackets
measured.
The greatest amount of play is in the torque plane.5
When using a full-sized archwire, there is still a
6-degree loss of torque, as calculated from bracket
slot size tolerances, but this can extend to 100 per
cent torque loss in a low torque prescription.6 These
are theoretical calculations that do not necessarily
40
Australian Orthodontic Journal Volume 26 No. 1 May 2010
represent actual values. For ease of use and patient
comfort it has been suggested that some play between
the wire and slot walls is reasonable,1 providing
torque to teeth such as the upper incisors is not compromised. Incorrectly torqued teeth may affect the
final occlusion, anterior tooth guidance and space in
the arch.
The method of manufacture affects the accuracy of
the slot walls and contributes to loss of torque.
Brackets cast from moulds are affected by shrinkage
and milling introduces various imperfections such as
grooves and striations and uncovers porosity in the
slot walls. To compensate for manufacturing imperfections and to ensure that the imperfections do not
interfere with archwire engagement, manufacturers
deliberately increase the slot dimensions and bevel
the edge of archwires.1 Torque-induced stresses such
as notching of the internal surface of walls of a bracket slot further increase bracket – wire play. FischerBrandies et al.2 suggested these stresses can lead to a
further 0.016 mm widening of bracket slots. We
should, however, expect manufacturers to produce
brackets and wires to accurate dimensions as these are
variables that can be controlled.
The effects of manufacturing inaccuracies on the
clinical performance of orthodontic appliances has
highlighted the need for a regulatory body, supported
by an appropriate legal framework, that ensures minimum standards of these devices. The German tolerance limits published in 2000 specify the tolerance
limits for orthodontic bracket slots should be no
more than 0.056 ± 0.04 mm.7 The American
Standards Association 2004 also stipulated their
bracket tolerances for slot height must be within
0.0025 mm.8 The Medical and Healthcare Products
Regulatory Agency (MHRA), set up in April 2003, is
ASSESSMENT OF SLOT SIZES IN SELF-LIGATING BRACKETS USING ELECTRON MICROSCOPY
the UK government agency responsible for ensuring
that medical devices work and are acceptably safe.
The MHRA have produced specific regulatory
guidance for manufacturers of dental appliances and
prostheses. The Medical Devices Directive provides
guidelines, which enable manufactured devices to
meet the requirements set. Some dental appliances,
made to specific prescriptions, may be defined as
custom-made devices and the requirements of the
Medical Devices Directive will apply to those who
wish to manufacture these products.9
Conclusions
1. The slot heights of upper left central incisor selfligating brackets from six manufacturers were greater
than the manufacturers’ stated dimension of 0.022
inch. The differences ranged from 5.1 per cent larger
(Speed) to 14.8 per cent larger (SmartClip) than the
0.022 inch dimension published.
2. There was considerable variation in slot sizes
between different bracket systems.
References
1.
2.
3.
4.
5.
6.
7.
8.
9.
Kusy RP, Whitley JQ. Assessment of second-order clearances
between orthodontic archwires and bracket slots via the
critical contact angle for binding. Angle Orthod 1999;69:
71–80.
Fischer-Brandies H, Orthuber W, Es-Souni M, Meyer S.
Torque transmission between square wire and bracket as a
function of measurement, form and hardness parameters. J
Orofac Orthop 2000;61:258–65.
Cash A, Good SA, Curtis RV, McDonald F. An evaluation of
slot size in orthodontic brackets – are standards as expected?
Angle Orthod 2004;74:450–3.
Kusy RP, Whitley JQ. Influence of archwire and bracket
dimensions on sliding mechanics: derivations and determinations of the critical contact angles for binding. Eur J
Orthod 1999;21:199–208.
Creekmore TD, Kunik RL. Straight wire: the next generation. Am J Orthod Dentofacial Orthop 1993;104:8–20.
Sebanc J, Brantley WA, Pincsak JJ, Conover JP. Variability
of effective root torque as a function of edge bevel on orthodontic arch wires. Am J Orthod 1984;86:43–51.
German Standards Tolerance Limits. January 2000.
American National Standards/American Dental Association
Specification No. 100 Orthodontic Brackets and Tubes.
2004.
EC Medical Devices Directives. Medicines and Healthcare
products Regulatory Agency. Directive 93/42/EEC. Updated
March 2008.
3. The walls of the slots diverged from the bracket
bases.
Acknowledgments
We wish to thank Ken Brady and the staff in the
Electron Microscopy Suite, King’s College Hospital,
for all their help and advice with this study.
Corresponding author
Dr Nidhi Bhalla
Department of Orthodontics
King’s College Hospital
Denmark Hill
London SE5 9RS
United Kingdom
Tel: 01483 571 122 Ext 4444
Email: nbbhalla@hotmail.com
Australian Orthodontic Journal Volume 26 No. 1 May 2010
41
Space planning sensitivity and specificity: Royal
London Space Planning and Korkhaus Analyses
Rania Dause, Martyn Cobourne and Fraser McDonald
Department of Orthodontics, King’s College London Dental Institute, London, United Kingdom
Objectives: To establish the sensitivity and specificity of the Korkhaus and Royal London Space Planning Analyses.
Methods: The sample consisted of 30 cases with two sets of study models and lateral cephalometric radiographs taken at least
three years apart. These were then further subdivided into Class I (N = 10), Class II division 1 (N = 10) and Class II division 2
cases (N = 10). The Royal London Space Planning Analysis and the Korkhaus Analysis were applied on these cases at both
times.
Results: Study model analysis: The Royal London Planning Analysis revealed that in Class I malocclusions, upper and lower arch
crowding and spacing changed significantly with time. The total space required and tooth size reduction for the lower arch
had also changed significantly. Additionally, in the Class II division 1 malocclusions, lower arch crowding and spacing, total
space required and the need for tooth size reduction had significantly increased, while, in Class II division 2 malocclusions, a
statistically significant increase was observed in the upper and lower arch crowding and spacing.
The Korkhaus Analysis showed that in Class I malocclusions a significant decrease was observed in the lower arch length and
the lower anterior arch width. The upper posterior (inter-molar) arch width had significantly increased. In Class II division 1 malocclusions the lower right posterior space available had decreased significantly. The upper posterior arch width and the lower
posterior arch width also significantly increased. In Class II division 2 malocclusions, a statistically significant decrease was
observed in the lower anterior arch length. There were no significant changes in all angular and the two linear measurements
for all classes.
Conclusions: The Royal London Space Planning Analysis and the Korkhause Analysis are clinically sensitive analyses. The Royal
London Space Planning Analysis lacks specificity to be a robust model for treatment planning; modification may be required
before this technique is accepted.
(Aust Orthod J 2010; 26: 42–48)
Received for publication: July 2009
Accepted: December 2009
Rania Dause: rania.dause@kcl.ac.uk
Martyn Cobourne: martyn.cobourne@kcl.ac.uk
Fraser McDonald: fraser.mcdonald@kcl.ac.uk
Introduction
Orthodontics is mainly a cosmetic specialty of
dentistry focused on the diagnosis, interception, and
treatment of malocclusions and associated facial
appearance. The ideal orthodontic result is to complete treatment by moving the teeth into stable and
aesthetically pleasing positions, without compromising their health either in the short- or long-term. In
order to achieve this we need an accurate and
thorough clinical evaluation and diagnosis.1 The
accurate assessment of crowding and/or space
requirements is a major part of this planning process;
the majority of the current populations seeking
42
Australian Orthodontic Journal Volume 26 No. 1 May 2010
orthodontics require treatment of crowding to relieve
the misalignment of the teeth.1,2
Space assessment can be undertaken in both the permanent and the mixed dentitions. Mixed dentition
space analysis is a method that predicts the mesiodistal widths of the unerupted permanent canines and
premolars in patients still awaiting the exfoliation of
primary teeth. Part of this analysis may identify a period
of space maintenance, regaining space already lost by
mesial migration, eruption guidance or serial extraction.
Conversely, the space requirements can be evaluated by a permanent dentition analysis when the
permanent dentition is fully erupted (the permanent
© Australian Society of Orthodontists Inc. 2010
ROYAL LONDON SPACE PLANNING AND KORKHAUS ANALYSES
crowded teeth, opening space for bridges, tooth
enlargement, mesial movement, arch constriction,
incisor retraction, palatal apical incisor torque and
levelling the occlusal curve. Space creation included
extraction, enamel reduction, distal movement, arch
expansion, incisor advancement and labial apical
incisor torque. The total space consumed should be
equal to the total space created such that neither
space excess nor deficiency is present at the end of the
space planning process. This is known as a zero
residue. This information can be used to decide the
need for extraction, plan anchorage management,
plan the mechanics for correction of arch relationships and identify whether the treatment objectives or
mechanics are to be modified.4,5
Figure 1. Korkhaus analysis kit (orthometer, divider and sliders).
dentition often excludes the eruption of the third
molars).3 One of the methods used to assess space
and formalise the process of treatment planning is the
Royal London Space Planning Analysis.4,5 It is a
protocol that incorporates space analysis with
treatment planning and is undertaken as part of the
treatment planning process after detailed clinical
examination, cephalometric analysis,6,7 and study
model analysis. It tries to establish a disciplined
approach to diagnosis and treatment planning and it
provides clinicians with a record to justify treatment decisions for professional accountability and
determines whether the treatment objectives are
achievable.4,5 In brief, this process is carried out in
two stages. The first stage calculates the total space
required in each dental arch to attain the treatment
objectives. These include measuring the crowding
and spacing, levelling the occlusal curve, arch width
changes, incisor A/P changes and upper incisor angulation/inclination. The second stage calculates any
additional space to be created or utilised including
tooth reduction/enlargement, extractions, space
opening for a bridge/implant, molar distal movement, molar mesial movement and differential
maxillary/mandibular growth.
Space planning measures those aspects of a malocclusion and proposed treatment that either consume or
create space.4,5 Space utilisation included aligning
On the other hand, the Korkhaus analysis is a technique designed to provide an accurate assessment for
the space requirements. This analysis requires a
specific kit, which includes an orthometer, dividers
and sliders (Figure 1). The orthometer is a device that
consists of a central white plastic disc with an
engraved scale and four windows, which rotate
around a scale, revealing numbers that represent different dimensions. The divider is used to measure the
tooth and arch widths. The sliders are transparent
plastic discs with engraved scales that are used for cast
and radiograph analysis.
In brief, the width of the four central incisors are
measured with the dividers, this value is then transferred to the SJ window (this includes a range of
normal values representing the sum of the mesiodistal widths of all central incisors) on the orthometer. The orthometer provides us with the required
values of the anterior arch length and width and posterior arch width. Then, using dividers, the space
available in the anterior arch length and width and
the posterior width are measured on the dental casts.
The difference between the space available and the
space required indicates the total amount of crowding/spacing, which are vital in the process of
treatment planning.
Treatment in the permanent dentition, whether
inclusive of crowding or spacing, can be carried out
by one of the following methods: dental crowding
can be treated by interproximal reduction,8,9 arch
expansion, inter-maxillary mechanics, extractions
with or without anchorage support,10 or surgically;
dental spacing can be treated by either closing those
spaces or relocating them.11
Australian Orthodontic Journal Volume 26 No. 1 May 2010
43
DAUSE ET AL
This study aimed to evaluate two methods of space
analysis using untreated cases of different malocclusions. The two techniques, the Korkhaus and Royal
London Space Analyses, both have limitations, but
we aimed to compare the two techniques to establish
if they were robust clinical adjuncts to treatment
planning.
Materials and methods
Study sample
This study used serial records collected by the late
Professor Leighton. The collection consists of the
records of 1095 reportedly untreated subjects who
had been followed from 1952 until the present. We
used the lateral skull radiographs and the study
models collected in the Leighton study.
The following selection criteria were used:
Methods
The cephalometric radiographs were traced and the
angular and distance measurements in the Eastman
cephalometric analysis used to determine if changes
occurred in the inclinations of the incisors or the
skeletal relationships.12,13
The two stages in the Royal London Space Planning
Analysis were applied to the paired study models to
determine the total space required and the amount of
space created/utilised in each dental arch.4,5
The Korkhaus Analysis was then applied to the
matching study models in which anterior arch length,
anterior and posterior arch widths and the space
available for the posterior teeth were measured.
1. No evidence of treatment. This could be:
Error study method
a. Extractions: this was validated by examination of
the study casts and, when required, the panoramic
radiograph.
Ten randomly selected sets of records that were not
part of this study were measured twice with a two
week interval between measurements, by the same
examiner. There was no systemic error and there were
no significant differences between the first and
second measurements.
b. Use of fixed appliances: this was determined by the
impression of brackets on the teeth of the study
models.
c. Use of removable appliances: there were seven cases
where the study model box had a significant number
of removable appliances which fitted the study
models, and extra-oral appliances.
Statistical method
2. Permanent dentition.
All statistical analyses were carried out using SPSS
15.0 for Windows (Statistics Package for the Social
Sciences).13 The T1 and T2 means and standard deviations for each reading and the differences between
the T1 and T2 readings were calculated. Paired t-tests
were used to determine the significant differences
between the two ages. The statistical significance was
set at the probability level of 0.05.
3. Class III malocclusions were excluded because
there were insufficient cases.
Results
The final sample was 30 cases with pairs of lateral
cephalometric radiographs and study models representing various types of malocclusion and different
levels of crowding: Class I (N = 10; 6 males, 4
females), Class II division 1 (N = 10; 5 males, 5
females) and Class II division 2 cases (N = 10; 6
males, 4 females). The records of each case were
selected at two different ages with a minimum of
three years apart. The mean age of the subjects at the
initial records was 12 years, 10 months (Range: 12
years 5 months to 13 years 10 months) and at the
The Royal London Space Analysis (Table I) revealed
that in Class I malocclusion, crowding and spacing in
the upper and lower arches changed significantly
(Mean T1: -0.10; Mean T2: -1.10, p = 0.004). The
total space required and tooth size reduction for the
lower arch has also changed significantly (Mean T1: 0.80; Mean T2: -2.10, p = 0.033). In Class II division
1 the lower arch crowding and spacing (Mean T1: 1.30; Mean T2: -2.30, p = 0.004), total space required
(Mean T1: -1.10; Mean T2: -2.20, p = 0.007) and the
need for tooth size reduction (Mean T1: 1.80; Mean
d. There was a small number of cases (< 20) where the
alignment of teeth on the final study models was
inconsistent with normal development, as judged by
an experienced clinician.
44
second set of records it was 16 years 2 months
(Range: 15 years 6 months to 17 years 7 months).
Australian Orthodontic Journal Volume 26 No. 1 May 2010
ROYAL LONDON SPACE PLANNING AND KORKHAUS ANALYSES
Table I. Comparisons of the Royal London Space Planning from T1 to T2.
Components
Mean difference
Class I
Crowding and spacing
Incisor A/P change
Total space required
Tooth reduction/enlargement
Class II division 1 Crowding and spacing
Incisor A/P change
Total space required
Tooth reduction/enlargement
Class II division 2 Crowding and spacing
Incisor A/P change
Total space required
1.00
0.10
0.81
-1.20
1.10
0.90
2.10
-0.10
1.20
-0.90
-0.10
Upper arch
SD difference
p
0.82
0.74
1.77
1.87
1.73
3.66
4.63
2.08
0.92
1.37
1.85
0.004
0.678
0.182
0.074
0.075
0.457
0.185
0.882
0.003
0.068
0.868
Mean difference
1.20
0.10
1.30
-0.80
1.00
0.00
1.10
-0.60
0.80
-0.20
0.50
Lower arch
SD difference
p
1.23
0.88
1.64
1.03
0.82
0.47
0.31
0.70
0.92
1.23
1.27
0.013
0.726
0.033
0.037
0.004
1.000
0.007
0.024
0.022
0.619
0.244
All measurements in mm
Paired t - test, statistically significant values in bold
Table II. Comparisons of the cephalometric measurements from T1 to T2.
SNA – SNA2
SNB – SNB2
ANB – ANB2
SNMx – SNMx2
MxMP – MxMP2
UISN – UISN2
UIMxP – UIMxp2
UI-APg – UI-APg2
LIMP – LIMP2
LIAPg – LIAPg2
Mean
difference
Class I
SD
difference
p
-0.50
-0.85
0.20
0.40
0.40
-0.55
-1.00
-0.35
0.10
-0.10
1.92
1.20
1.32
3.24
2.50
1.83
2.91
0.82
2.56
0.91
0.389
0.052
0.642
0.705
0.389
0.117
0.305
0.209
0.904
0.735
Class II division 1
Mean
SD
difference
difference
T2: 2.40, p = 0.024) has significantly increased. In
Class II division 2 malocclusions statistically significant increases were observed in the upper and lower
arch crowding and spacing (Mean T1: -1.20; Mean
T2: -2.40, p = 0.003).
There were no significant cephalometric changes for
all classes from T1 to T2. The detailed results are
shown in Table II.
The Korkhaus Analysis (Table III) showed that in
Class I malocclusion a significant decrease was
observed in the lower arch length (Mean T1: 16.05;
Mean T2: 15.60, p = 0.041) and the lower anterior
arch width (Mean T1: 36.05; Mean T2: 35.45,
-0.80
-0.95
0.10
0.70
1.10
-0.10
0.70
-0.10
-0.80
-0.05
1.99
1.38
1.29
1.34
3.00
3.84
3.40
1.74
2.10
1.21
p
0.235
0.058
0.811
0.132
0.276
0.936
0.531
0.860
0.259
0.899
Class II division 2
Mean
SD
difference
difference
0.00
-0.45
0.40
0.60
0.90
-0.90
-0.60
0.30
1.80
-0.15
1.70
2.43
1.58
1.35
2.02
2.85
2.72
1.00
5.39
2.33
p
1.000
0.573
0.443
0.193
0.193
0.343
0.502
0.370
0.319
0.843
p = 0.018). The upper posterior (inter-molar) arch
width significantly increased (Mean T1: -4.40; Mean
T2: -4.90, p = 0.015). In the Class II division 1 group,
the lower right posterior space available has decreased
significantly (Mean T1: 21.25; Mean T2: 20.65, p =
0.030). The upper posterior arch width (Mean T1:
47.05; Mean T2: 47.50, p = 0.041) and the lower
posterior arch width (Mean T1: 45.40; Mean T2:
46.15, p = 0.003) have significantly increased. In
Class II division 2 a statistically significant decrease
was observed in the lower anterior arch length (Mean
T1: 15.51; Mean T2: 14.85, p = 0.026). Additionally,
there were no significant changes in the posterior arch
width found in the Class II division 2 malocclusions.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
45
DAUSE ET AL
Table III. Comparisons of the Korkhaus Analysis from T1 to T2.
Mean
difference
Upper arch
SD
difference
p
Mean
difference
Lower arch
SD
difference
p
Class I
Anterior arch length
Anterior arch length difference
Anterior arch width
Posterior arch width
Posterior arch width difference
0.50
-0.50
0.30
0.35
0.50
0.91
1.08
0.95
0.78
0.53
0.117
0.117
0.343
0.191
0.015
0.45
0.70
0.60
0.25
0.50
0.60
0.95
0.66
1.40
1.43
0.041
0.045
0.018
0.586
0.299
Class II division 1
Anterior arch length
0.10
0.74
0.678
0.60
1.49
0.234
Anterior arch width
-0.25
1.11
0.495
0.20
0.79
0.443
Right posterior space available
Posterior arch width
Posterior arch width difference
0.25
-0.45
-0.70
0.49
0.60
1.06
0.138
0.041
0.066
0.60
-0.75
-0.90
0.74
0.59
1.20
0.030
0.003
0.041
Anterior arch length
Anterior arch width
Posterior arch width
0.60
0.55
0.00
0.88
1.55
0.82
0.058
0.292
1.000
0.66
0.35
-0.15
0.78
0.63
1.16
0.026
0.111
0.691
Class II division 2
Measurements in mm
Paired t - test, statistically significant values in bold
Discussion
The sample consisted of 30 cases with two sets of
records (study models and lateral cephalometric)
taken on two occasions at least three years apart. The
cases were derived from the Leighton collection to
evaluate the sensitivities and specificities of the
Korkhaus Analysis and the Royal London Space
Planning Analysis. By definition, sensitivity is the
proportion of positives correctly identified by the
test and specificity is the proportion of negatives
correctly identified by the test.14
The intercanine and intermolar widths, and arch
length were significantly reduced in the present study
in all malocclusions when assessed using the
Korkhaus analysis. These findings were consistent
with previous studies.15–17 Bishara and coworkers
assessed several parameters including arch widths and
length as well as crowding and space requirements in
a sample from Iowa Longitudinal Growth Study.15
They found an increase in crowding and as a result
space requirements as well as a reduction in arch
widths and lengths. The decrease in mandibular arch
length was significantly greater in the male subjects as
compared with the female subjects (p < 0.001). This
parameter is of great clinical value as it holds a longterm implication on the retention and stability of
46
Australian Orthodontic Journal Volume 26 No. 1 May 2010
orthodontic treatment. This has been shown by Little
and other investigators.18,19 Little and Riedel have
reviewed records of 31 subjects at 10 and 20 years
post-retention. They found that arch widths and
length decreased after the retention period whereas
crowding increased. Only 10 per cent of the subjects
were considered to retain an acceptable alignment
after 20 years post-retention.19
The present study showed statistically significant
changes in the amount of crowding and space
requirements using both analyses. These were
expected dental changes with normal growth and
development of the dentofacial complex.17,20
However, correlating the two parameters is complex
in nature. Several other factors were considered in the
literature to play a role in the changes that occur to
the mixed and permanent dentitions.17,20 Incisor
crowding was linked to factors such as: the characteristics of the dentition and the discrepancy between
the mesiodistal and buccolingual dimensions of the
incisors, physiological forces such as mesial drift, and
the uprighting of mandibular incisor with growth of
the mandible.18,19 In agreement with others we
believe though that the overriding factor in crowding
and space requirement is the reduction in arch widths
and length.21,22
ROYAL LONDON SPACE PLANNING AND KORKHAUS ANALYSES
Royal London Space Planning Analysis is unable to
identify and quantify growth imbrications (Figure 2).
This is clearly demonstrated in the inability of the
analysis to predict differential growth of dentoalveolar complex and mesial drift of the buccal segment.
Figure 2. An example of a Class II division 1 case showing anterior point
displacement from the time of T1 (left) to T2 (right).
In the current study, it was observed that crowding
was more pronounced in Class II division 2 subjects
when compared to Class I and Class II division 1 subjects. This is clearly related to the greater reduction in
arch widths and length, which featured in the Class II
division 2 subjects. These significant changes may be
attributed to the fact that Class II division 2 malocclusion is characterised by reduced vertical proportions, which would influence the amount of
crowding and arch length changes as the mandibular
incisors tend to tip lingually in low angle subjects.
The ability of both analyses to identify dental changes
such as crowding, arch width and arch length reduction that occur with growth and development of the
craniofacial complex clearly shows a good sensitivity
for the Korkhaus and the Royal London Space
Analyses.
However, the problems initially identified with the
Royal London Space Planning Analysis as it is currently described do not take into consideration midline correction and arch asymmetries. These are
clearly significant areas that need consideration for
treatment planning and should be factored into
orthodontic treatment decisions.23 By definition,
‘dental midline’ is the midsagittal line of maxillary
and mandibular dental arches. Each arch has its own
midline. The upper incisor midline should coincide
with that of the maxilla and the lower incisor midline
should coincide with that of the mandible.24 Whilst
dental arch asymmetry is defined as the imbalance
between left and right sides of the jaws in terms of
shape/archform and occlusion, this can be due to a
unilateral crossbite.23
The Royal London Space Planning Analysis is reliable, but it’s specificity is questionable.25 As it appears
that, like most other space planning techniques, the
Cephalometric analysis showed no significant
changes in the angular and linear measurements for
all classes from T1 to T2. One reason may be attributed to the fact that radiographs, unlike study models,
are two-dimensional views of a three-dimensional
structure. For example, it is not possible to calculate
or observe the changes in arch widths using a lateral
cephalometric radiograph. Another reason would be
the fact that some of the subjects had past their
growth spurts and as a result any changes would be
of small magnitude and, therefore, would not be
significant.
It is also apparent that there are different requirements of treatment planning for differing incisal
relationships i.e. Class I, Class II division 1 and Class
II division 2 relationships. There appears no clear or
robust consideration of the differing growth changes
that may influence the outcome of treatment as
dependent on the incisal relationship and the underlying growth pattern.
Conclusion
The present study demonstrated an increase in the
anterior crowding and a decrease in the total arch
length and arch widths. The Royal London Space
Planning Analysis and the Korkhaus Analysis are clinically sensitive analyses in that they identified this
change. As anticipated, the Royal London Space
Planning Analysis was unsuccessful in indicating the
growth imbrications, which would have adverse
implications on the treatment planning process. The
Royal London Space Analysis lacks specificity to be a
fully robust model for treatment planning; modification may be required prior to the complete acceptance of this technique to identify factors that are not
incorporated within its basic calculations. Clearly
there is need for further clarification if such a method
is to be developed.
The present work sheds light on the clinical value of
two processes in space planning. However, the sample
was relatively small. It is recommended that the study
is repeated with more subjects to increase the reliability, minimise the bias and improve the validity of the
outcomes.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
47
DAUSE ET AL
Corresponding author
11
Dr Rania R. Dause
Department of Orthodontics
Floor 22, Tower Wing
King’s College London Dental Institute
St Thomas St
London SE1 9RT
United Kingdom
Email: rania.dause@kcl.ac.uk
12.
References
Proffit William R. Contemporary Orthodontics. St. Louis;
Mosby, 2007;195–218.
2. Mockers O, Aubry M, Mafart B. Dental crowding in a prehistoric population. Eur J Orthod 2004;26:151–6.
3. Shellhart WC, Lange DW, Kluemper GT, Hicks EP, Kaplan
AL. Reliability of Bolton tooth-size analysis when applied to
crowded dentitions. Angle Orthod 1995;65:327–34.
4. Kirschen RH, O’Higgins EA, Lee RT. The Royal London
Space Planning: an integration of space analysis and treatment planning: Part I: Assessing the space required to meet
treatment objectives. Am J Orthod Dent Orthop 2000a;118:
448–55.
5. Kirschen RH, O’Higgins EA, Lee RT. The Royal London
Space Planning: an integration of space analysis and treatment planning: Part II: The effect of other treatment procedures on space. Am J Orthod Dent Orthop 2000b;118:
456–61.
6. Brown M. Eight methods of analysing a cephalogram to
establish anteroposterior skeletal discrepancy. Br J Orthod
1981;8:139–46.
7. Paskow H. Self-alignment following interproximal stripping.
Am J Orthod 1970;58:240–9.
8. Abu Alhaija ES, Al-Khateeb SN, Al-Nimri KS. Prevalence of
malocclusion in 13–15 year-old North Jordanian school
children. Community Dent Health 2005;22:266–71.
9. Chate RA. The burden of proof: a critical review of orthodontic claims made by some general practitioners. Am J
Orthod Dent Orthop 1994;106:96–105.
10. Chaimattayompol N, Wong SX. Diagnostic management of
interdental spacing. J Prosthet Dent 2000;84:467–9.
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Mills JR. The application and importance of cephalometry
in orthodontic treatment. Orthodontist 1970;2:32–47.
Jacobson A. Radiographic cephalometry: from basics to
video-imaging. Quintessence Publishing Co. Inc., 1995;
53–63.
The Statistics Package for the Social Sciences website.
http://www.spss.com
Altman DG. Practical statistics for medical research.
London: Chapman and Hall, 1991;409–19.
Bishara SE, Jakobsen JR, Treder JE, Stasi MJ. Changes in the
maxillary and mandibular tooth size-arch length relationship
from early adolescence to early adulthood. A longitudinal
study. Am J Orthod Dent Orthop 1989;95:46–59.
Bishara SE, Treder JE, Jakobsen JR. Facial and dental
changes in adulthood. Am J Orthod Dent Orthop 1994;106:
175–86.
Lundström A. Changes in crowding and spacing of the teeth
with age. Dent Pract Dent Rec 1969;19:218–24.
Little RM, Wallen TR, Riedel RA. Stability and relapse of
mandibular anterior alignment-first premolar extraction
cases treated by traditional edgewise orthodontics. Am J
Orthod 1981;80:349–65.
Little RM, Riedel RA. An evaluation of changes in mandibular anterior alignment from 10 to 20 years postretention. Am J Orthod Dent Orthop 1988;93:423–8.
Thilander B. Dentoalveolar development in subjects with
normal occlusion. A longitudinal study between the ages of
5 and 31 years. Eur J Orthod 2009;31:109–20.
O’Higgins EA, Lee RT. How much space is created from
expansion or premolar extraction? J Orthod 2000;27:11–13.
O’Higgins EA, Kirschen RH, Lee RT. The influence of maxillary incisor inclination on arch length. Br J Orthod 1999;
26:97–102.
Langberg BJ, Arai K, Minerc RM. Transverse skeletal and
dental asymmetry in adults with unilateral lingual posterior
crossbite. Am J Orthod Dent Orthop 2005;127:6–16.
Jerrold L, Lowenstein LJ. The midline: diagnosis and treatment. Am J Orthod Dent Orthop 1990;97:453–62.
Al-Abdallah M. Sandler J. O’Brien K. Is the Royal London
Space Analysis reliable and does it influence orthodontic
treatment decisions? Eur J Orthod 2008;30:503–7.
Response of the expanded inter-premaxillary
suture to intermittent compression.
Early bone changes
Tancan Uysal, * Huseyin Olmez, † Mihri Amasyali, † Yildirim Karslioglu, + Atilla Yoldas ±
and Omer Gunhan +
Department of Orthodontics, Erciyes University, Kayseri, Turkey and the King Saud University, Riyadh, Saudi Arabia,* Departments of
Orthodontics† and Pathology+ Gülhane Military Medical Academy, Ankara and the Veterinary Research and Control Institute, Adana,± Turkey
Objective: To determine the response of the expanded premaxillary suture in the rat to an externally applied force. Specifically,
to investigate early bone changes in the expanded suture to intermittent loading and unloading.
Methods: Twenty-four 50 to 60 day-old Wistar rats were assigned to three groups. The inter-premaxillary sutures in all animals
were expanded with a 50 g force applied to the upper incisors. Group I served as the control, whereas in Groups II and III
the incisors were subjected to intermittent loading and unloading after five days of expansion. The intermittent forces were
produced by a cam (0.416 mm, 100 cycles per minute) applied to the disto-gingival margins of the upper incisors. The
mechanical stimuli were applied daily over nine days for six seconds in Group II (30 grams force, 10 cycles/day) and
10 minutes in Group III (30 grams force, 1000 cycles/day). Bone regeneration in the suture was evaluated histomorphometrically. The area of new bone (µm2), the perimeter around the new bone (µm), Feret’s diameter (µm) and the percentage of
new bone to non-ossified tissue (%) were measured and compared.
Results: Statistically significant differences were found between the groups for all histomorphometric parameters. New bone
area (p < 0.001), bone perimeter (p < 0.001), Feret’s diameter (p < 0.001) and percentage of new bone (p < 0.001) were
significantly larger in the experimental groups as compared with the Control group. The histomorphometric measurements
confirmed that more new bone was deposited in the sutures subjected to intermittent loading and unloading.
Conclusion: The application of cyclic loading and unloading to the orthopaedically expanded inter-premaxillary suture
during the early retention phase stimulated the formation of new bone.
(Aust Orthod J 2010; 26: 49–55)
Received for publication: July 2009
Accepted: January 2010
Tancan Uysal: tancanuysal@yahoo.com
Huseyin Olmez: holmez60@yahoo.com
Mihri Amasyali: mamasyali@yahoo.com.tr
Yildirim Karslioglu: ykarslioglu@gmail.com
Atilla Yoldas: yoldasatilla@yahoo.com
Omer Gunhan: omergunhan@gata.edu.tr
Introduction
Rapid maxillary expansion (RME) is often used to
correct a transverse maxillary deficiency. During
RME the mid-palatal suture is widened and the two
maxillae forced apart by an appliance anchored to the
buccal teeth. Following expansion, bone is deposited
in the mid-palatal suture.1–4 It is well-known that
even after a period of retention the expanded maxillae can ‘rebound’ to their original positions, in some
cases by as much as 90 per cent.5–7
© Australian Society of Orthodontists Inc. 2010
Deposition of bone in the expanded suture starts at
the end of active treatment phase and continues for
60 to 90 days.8,9 Although the reason for the postexpansion relapse is not fully understood, the quality
and rapidity of bone deposited in the mid-palatal
suture during and after expansion may influence the
relapse.1 It could be postulated that accelerated bone
formation in the suture after expansion may reduce
the amount of time required for retention and
prevent the maxillae from relapsing.1,2
Australian Orthodontic Journal Volume 26 No. 1 May 2010
49
UYSAL ET AL
Attempts to shorten the healing period in a healing
fracture or distraction callus may throw further light
on the relapse that follows maxillary expansion.
Various methods have been used to stimulate the deposition of new bone in a fracture callus. Demineralised bone matrix, autologous marrow cells or cultured periosteal cells have been transplanted into the
distracted area and bone formation in the callus has
been stimulated either mechanically, electrically or
electromagnetically.10–16 Micro-movements applied
externally to a callus may result in the early formation
of new bone which also happens to be ‘stronger’.17–23
Recent evidence suggests that cyclic compression may
be more beneficial than cyclic distraction, but the evidence is by no means clear-cut.21–23 The aim of this
experimental study was to evaluate the effects of
externally applied, intermittent compression on bone
regeneration in the expanded inter-premaxillary
suture in the rat.
Material and methods
Animals
Twenty-four male 50 to 60 day-old Wistar rats with a
mean weight of 210.63 ± 20.95 g were used. All animals were housed in polycarbonate cages, subjected
to a 12-hour light – dark cycle at the constant temperature of 23 °C and fed a standard pellet diet
(Expanded pellets, Stepfield, Witham, Essex, UK)
with tap water ad libitum. Permission was obtained
from the Gulhane Military Medical Academy, Ethics
Committee of Experimental Animals after the
Research Scientific Committee at the same institution had approved the experimental protocol. The
experiments were carried out in the Department of
Experimental Animals, Research and Development
Center, Gulhane Military Medical Academy.
Appliance placement
The animals were anaesthetised with an intramuscular injection of Xylasine (Bayer, Istanbul,
Turkey) and Ketamine (Parke-Davis, Istanbul,
Turkey) at 0.5 ml/kg and 1 ml/kg body weight,
respectively. The expansion appliances were helical
springs fabricated from 0.014 inch stainless steel wire
inserted in holes drilled close to the gingival margins
of both upper incisors. The springs were activated
to deliver a force of 50 g and were not reactivated
during the 5-day expansion period.
50
Australian Orthodontic Journal Volume 26 No. 1 May 2010
After five days the springs were removed and replaced
with short lengths of rectangular retaining wire.
Tooth separation was maintained for 10 days. The
distance between the mesial edges of the upper
incisors was measured at the beginning of the experiment and at the end of expansion with a digital
caliper (MSI-Viking Gage, SC, USA).
Application of intermittent compression
The animals were randomly allocated to three groups
with eight rats in each group. The animals in Group
I were not subjected to intermittent compression and
served as the control. In Groups II and III, intermittent compression was applied at the disto-gingival
margins of the upper incisors 24 hours after five days
of expansion and continued for a further nine days.
The intermittent compressive loads (100/minute)
were produced by a cam with an amplitude of 0.416
mm operated by an electrical motor. Intermittent
compression was applied by two acrylic pads placed
on the disto-gingival margins of the incisors for six
seconds in Group II (30 grams force, 10 cycles/day)
and 10 minutes in Group III (30 grams force, 1000
cycles/day). The stimuli were applied daily from the
second to the seventh day of retention.
Specimen preparation
After the retention period of 10 days, the rats were
sacrificed with an overdose of Ketamine and Xylasine
and their premaxillae were dissected out and fixed in
10 per cent formalin. After fixation, the retaining
wires were removed and the premaxillae were decalcified with 5 per cent formic acid for three days. After
decalcification, the premaxillae were cut into blocks
with one cut passing through the incisor crowns at
the alveolar crest and perpendicular to the sagittal
plane, the second cut 4 mm apical to the first cut.
The sections were rinsed, trimmed and embedded in
paraffin. The paraffin blocks were sectioned serially at
5 µm intervals.
Histomorphometric analysis
The histological sections were stained with haematoxylin and eosin (Figure 1). The histomorphometric
measurements were performed 200 µm beneath the
oral surface of the osseous palate because bone formation in the surface layer was sometimes irregular
and unsuitable for quantitative measurement. The
sections were viewed under a microscope (Olympus
RESPONSE OF THE EXPANDED INTER-PREMAXILLARY SUTURE TO INTERMITTENT COMPRESSION
Figure 2. Measurement of an outlined area of new bone (µm2).
Figure 1. Histological section of an expanded suture (H&E, x40
magnification).
CX41/DP25 Research System, Olympus Corporation, Japan) and the histomorphometric measurements were calculated with an image analysis
programme.
The histomorphometric measurements were performed by two assessors who were blinded to the
identity of the sections. The final results are averages
of these separate evaluations. Two histological
sections from each animal were analysed and representative areas, which were defined beforehand, were
captured at x400 magnification. The image analysis
software, Image-J (US National Institutes of Health,
Bethesda, MA, USA) was used to compute the histomorphometric measurements.24 The following
parameters were measured: new bone area (µm2),
bone perimeter (µm), Feret’s diameter (µm) and
percentage of new bone. These basic planimetric
measurements provided a description of the amount
of new bone. The new bone area is the total crosssectional area of new bone. The bone perimeter and
Feret’s diameter are the length of the perimeter
around the new bone and the maximum distance
between any two points on the perimeter, respectively. Two separate image analysis macroprogrammes were written by one of the authors
(Y.K.) to increase the contrast between the bone and
surrounding tissue and display the basic planimetric measurements of the outlined new bone
Figure 3. The number of grid intersections on new bone and non-osseous
connective tissue were counted and the percentage of new bone calculated.
(Figure 2). The second macro enhanced each image
and superimposed a grid, consisting of squares with
areas of 1000 µm2, on the image. Intersections of the
grid superimposed on new bone were recorded. After
recording the new bone, non-ossified areas were
recorded in the same manner. At the end of the
macro, the programme calculated the percentage of
new bone (Figure 3).
Statistical analysis
Statistics were analysed with the Statistical Package
for Social Sciences 13.0 (SPSS for Windows, SPSS
Inc, Chicago, IL, USA). A non-parametric test, the
Kruskal-Wallis one-way analysis of variance was used
to compare the groups and a one-sided MannWhitney U test was used to determine which groups
Australian Orthodontic Journal Volume 26 No. 1 May 2010
51
UYSAL ET AL
Table I. Comparisons of the histomorphometric measurements.
Parameters
Minimum
Maximum
p
Multiple comparisons (p)
Group II
Group III
Group
N
Mean
SD
SE
Area (µm2 )
I
II
III
8
8
8
57.64
104.51
130.96
19.98
14.15
19.85
7.55
5.34
3.72
28.90
89.57
84.67 129.60
112.55 142.04
0.000
0.000
0.000
0.012
Perimeter (µm)
I
II
III
8
8
8
137.07
178.20
193.83
15.21
14.76
19.18
1.96
1.79
3.46
82.47 236.19
125.55 232.21
163.71 289.71
0.000
0.000
0.000
0.039
Feret's diameter (µm)
I
II
III
8
8
8
15.21
59.81
66.06
19.59
14.78
13.28
7.40
5.58
1.24
12.08
42.87
22.77
17.15
76.11
103.39
0.000
0.000
0.000
NS
Newly formed bone (%)
I
II
III
8
8
8
34.86
58.78
70.14
11.90
10.35
8.26
4.49
3.91
3.12
20.00
44.44
60.00
55.55
76.34
84.84
0.000
0.001
0.000
NS
Significant values in bold
NS, not significant
were significantly different. Probability values less
than 0.05 were accepted as significant.
Results
All animals survived to the end of the study. Deep
mucosal infections, dehiscences or other adverse
effects were not observed in any animals. The expansion appliances were well-tolerated and the animals
gained weight. Two rats in Group II and one rat in
Group III lost weight during retention, but subsequently gained weight. As no statistically significant
changes in body weight were found during the expansion and retention periods there was no reason to
weight-correct the data.
The histological sections confirmed that the interpremaxillary sutures were expanded in all groups and
there was no statistically significant difference
(p = 0.071) in the amount of expansion in the groups.
The ANOVA analysis did, however, show significant
differences between the groups for the area of new
bone, the bone perimeter, Feret’s diameter and the
percentage of new bone formed (Table I).
With regard to the areas of new bone, the highest
value was observed in Group III (Mean: 130.96 ±
19.85 µm2) and the lowest value in Group I (Mean:
57.64 ± 19.98 µm2) and the difference between these
groups was statistically significant (p < 0.001).
Significant differences were also found between
52
Australian Orthodontic Journal Volume 26 No. 1 May 2010
Groups I and II (p < 0.001) and Groups II and III
(p = 0.05) (Figures 4 and 5).
The perimeters around the islands of new bone in
Groups I and II, I and III, and II and III were significantly different (Table I). The mean perimeter
around the new bone in Group III (Mean: 193.83 ±
19.18 µm) was significantly longer than the mean
perimeter in Group I (Mean: 137.08 ± 15.21 µm)
(p < 0.001) and Group II (Mean: 178.20 ± 14.76
µm) (p = 0.039). The mean bone perimeter measurements in Group I and Group II were also significantly
different (p < 0.001).
Statistically significant differences were found
between Feret’s diameters in Groups I and II (p <
0.001) and Groups I and III (p < 0.001). No significant difference was found between Groups II and III.
The greatest percentage of new bone was found in
Group III (Mean: 70.14 ± 8.26 per cent) and the lowest percentage of new bone in Group I (Mean: 34.86
±11.89 per cent) and the difference was statistically
significant (p < 0.001). A significant difference was
also found between Groups I and II (p < 0.001).
Discussion
To our knowledge, this study is the first to report that
externally applied intermittent compression increased
bone healing in the expanded inter-premaxillary
RESPONSE OF THE EXPANDED INTER-PREMAXILLARY SUTURE TO INTERMITTENT COMPRESSION
Figure 4. A Group III specimen (Intermittent compression, 1000 cycles/day),
showing large amounts of new bone, indicating a later stage of bone formation (HE, x200 magnification). O, old bone; W, expanded suture; N, new
bone; C, well-organised fibrous connective tissue.
Figure 5. A Group I specimen (Control group) showing the beginning of
bone formation (HE 200X magnification). A, old bone; B, osteoblastic area;
C, connective tissue, containing some inflammatory cells.
suture in the rat. More new bone was deposited in the
expanded suture following intermittent compression
than in the control suture, leading to a more
advanced stage of healing.
opening (between 297.17 and 371.23 µm) after five
days. Although we found no difference between the
groups in the amount of expansion, the histomorphometric parameters (i.e. area of new bone,
perimeter around the new bone, Feret’s diameter and
the percentage of new bone to non-ossified tissue)
were significantly less in the Control group, indicating that new bone deposited along the sutural margins had reduced the widths of the inter-premaxillary
sutures in the experimental groups. Intermittent
compression of the edges of the expanded premaxillae
presumably resulted in some force (compression
and/or relaxation) being transferred to the healing
tissues in the suture in spite of the retaining wire.
There have been several reports in the orthopaedic
literature that an intermittent mechanical force
stimulates the formation of new bone, but in the
orthodontic literature few studies have been carried
out to stimulate regeneration in the mid-palatal/
inter-premaxillary suture after expansion.1,2 Recently,
we investigated the effects of dietary boron in rabbits
and locally administered ED-71 on bone formation
in the mid-palatal suture in rats, and found that these
agents stimulated bone regeneration during the
expansion and retention periods.3,4
During expansion a multi-factorial adaptive response
takes place in the mid-palatal suture. Mechanical
expansion disrupts the orderly sutural structure and
induces a chain of events that restore the suture to its
original architecture.25 In the present study, we
followed the sutural response to intermittent
compression histomorphometrically: a method that
provides reliable quantitative information on
bone remodelling in experimental and in-vitro
conditions.1–4,26
The width of the normal inter-premaxillary suture in
young rats is approximately 20–60 µm.27 Burstone
and Shafer28 determined that expansion of the suture
over a period of five days ‘opened’ the suture, on average, 380 ± 10 µm. Our springs achieved slightly less
Animals have been used to study the effects of force
on the rates of bone formation in the craniofacial
sutures. While monkeys and cats have similar maxillary sutures to man and have been used in maxillary
expansion experiments, rabbits and rats are less
costly and give a clear picture of the changes in a
suture under stress.27 In view of the ethical and cost
considerations, we chose the rat to investigate the
effects of mechanical stimulation on bone modelling.
The optimal mechanical stimulation to accelerate
bone healing has not been determined. To date, studies have focused on the magnitude of the micromovement (i.e. the amplitude) and the delay before
loading. Several reports indicate that immediate and
early mechanical interventions are the most effective,
while other authors have suggested that a short delay
Australian Orthodontic Journal Volume 26 No. 1 May 2010
53
UYSAL ET AL
may be necessary to allow neurovascularisation to
occur.29–32 We decided on the latter course of action
and applied an intermittent mechanical force to the
premaxillae 24 hours after the expansion.
Similar uncertainty exists concerning the frequency
and magnitude of loading on bone healing. For
example, a wide range of load and strain magnitudes
have been studied in sheep models.20,33 Some investigators were able to both enhance and inhibit bone
healing with different combinations of the timing of
load initiation and load amplitude.16 It appears that a
stronger callus occurs if axial cyclic compression is
applied after a short delay and at a low load amplitude.16 For this reason we used a low load amplitude
of only 30 grams (the expansion force was 50 grams)
and applied the force after a short delay.
It is uncertain whether it is the compressive or distractive displacements that enhance new bone formation.23 There appears to be a critical number of
loading cycles necessary to enhance new bone formation: in a fractured bone increasing the number of
loading cycles above the critical value did not result in
more new bone.34 We found significant histomorphometric differences in bone area and perimeter
between the Groups II and III (in both cases the
Group II findings were less than the Group III findings) which suggests that high loading cycles may
enhance bone formation in the inter-premaxillary
suture.
Melikgazi
Kayseri
Turkey
Email: tancanuysal@yahoo.com
References
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Conclusion
The application of cyclic micromovements to the
expanded inter-premaxillary suture during the early
phase of retention stimulates bone formation and
improves healing. Future studies will investigate
whether additional loading cycles enhance new bone
formation in inter-premaxillary suture in the rat.
Acknowledgments
12.
13.
14.
15.
This work was supported by a research grant from
Gulhane Military Medical Academy Research
Scientific Committee (AR-2009-05).
16.
Corresponding author
Dr Tancan Uysal
Erciyes Üniversitesi
Diş Hekimliği Facültesi
Ortodonti Anabilum Dall, 38039
54
Australian Orthodontic Journal Volume 26 No. 1 May 2010
17.
Saito S, Shimizu N. Stimulatory effects of low-power laser
irradiation on bone regeneration in midpalatal suture during
expansion in the rat. Am J Orthod Dentofacial Orthop
1997;111:525–32.
Sawada M, Shimizu N. Stimulation of bone formation in
the expanding mid-palatal suture by transforming growth
factor-beta 1 in the rat. Eur J Orthod 1996;18:169–79.
Uysal T, Ustdal A, Sonmez MF, Ozturk F. Stimulation of
bone formation by dietary boron in an orthopedically
expanded suture in rabbits. Angle Orthod 2009;79:984–90.
Uysal T, Amasyali M, Enhos S, Sonmez MF, Sagdic D. Effect
of ED-71, a new active vitamin D analog, on bone formation in an orthopedically expanded suture in rats. A histomorphometric study. Eur J Dent 2009;3:165–72.
Krebs AA. Midpalatal suture expansion studied by the
implant method over a seven-year period. Trans Eur Orthod
Soc 1964;131–42.
Vardimon AD, Graber TM, Voss LR. Stability of magnetic
versus mechanical palatal expansion. Eur J Orthod 1989;11:
107–15.
Timms DJ. Long term follow-up of cases treated by rapid
maxillary expansion. Trans Eur Orthod Soc 1976;52:
211–15.
Haas AJ. The treatment of maxillary deficiency by opening
the midpalatal suture. Angle Orthod 1965;35:200–17.
Cleall JF, Bayne DI, Posen JM, Subtelny JD. Expansion of
the midpalatal suture in the monkey. Angle Orthod 1965;
35:23–35.
Hagino T, Sato H, Yokoyama Y, Akamatsu N. Shortening of
bone union in limb lengthening. J Jpn Orthop Assoc
1995;64: 928.
Hamanishi C, Yoshii T, Totani Y, Tanaka S. Lengthened
callus activated by axial shortening: Histological and cytomorphometrical analysis. Clin Orthop Relat Res 1994;307:
250–4.
Tsubota S, Tsuchiya H, Shinokawa Y, Minematsu K, Tomita
K. Osteoblast-like cell transplantation to the distracted
callus. J Jpn Soc External Fixation 1997;81–B:125–9.
Kassis B, Glorion C, Tabib W, Blanchard O, Pouliquen J.
Callus response to micromovement after elongation in the
rabbit. J Pediatr Orthop 1996;16:480–3.
Pepper JR, Herbert MA, Anderson JR, Bobechko WP. Effect
of capacitive coupled electrical stimulation on regenerate
bone. J Orthop Res 1996;14:296–302.
van Roermund PM, ter Haar Romeny BM, Hoekstra A,
Schoonderwoert GJ, Brandt CJ, van der Steen SP et al. Bone
growth and remodelling after distraction epiphysiolysis of
the proximal tibia of the rabbit: Effect of electromagnetic
stimulation. Clin Orthop Relat Res 1991;266:304–12.
Gardner MJ, van der Meulen MC, Demetrakopoulos D,
Wright TM, Myers ER, Bostrom MP. In vivo cyclic axial
compression affects bone healing in the mouse tibia. J
Orthop Res.2006;24:1679–86.
Claes LE, Heigele CA, Neidlinger-Wilke C, Kaspar D, Seidl
W, Margevicius KJ, Augat P. Effects of mechanical factors on
the fracture healing process. Clin Orthop Relat Res 1998;
355:S132–S47.
RESPONSE OF THE EXPANDED INTER-PREMAXILLARY SUTURE TO INTERMITTENT COMPRESSION
18. Goodship AE, Kenwright J. The influence of induced micromovement upon the healing of experimental tibial fractures.
J Bone Joint Surg Br 1985;67:650–5.
19. Kenwright J, Richardson JB, Cunningham JL, White SH,
Goodship AE, Adams MA, Magnussen PA, Newman JH.
Axial movement and tibial fractures. A controlled randomized trial of treatment. J Bone Joint Surg Br 1991;73:654–9.
20. Claes LE, Heigele CA. Magnitudes of local stress and strain
along bony surfaces predict the course and type of fracture
healing. J Biomech 1999;32:255–66.
21. Augat P, Merk J, Wolf S, Claes L. Mechanical stimulation by
external application of cyclic tensile strains does not effectively enhance bone healing. J Orthop Trauma 2001;15:
54–60.
22. Matsushita T, Kurokawa T. Comparison of cyclic compression, cyclic distraction and rigid fixation. Bone healing in
rabbits. Acta Orthop Scand 1998;69:95–8.
23. Hente R, Füchtmeier B, Schlegel U, Ernstberger A, Perren
SM. The influence of cyclic compression and distraction on
the healing of experimental tibial fractures. J Orthop Res
2004;22:709–15.
24. Rasband WS. Image-J, U.S. National Institutes of Health,
Bethesda, Maryland, USA, http://rsb.info.nih.gov/ij/,
1997–2008.
25. Chang HN, Garetto LP, Potter RH, Katona TR, Lee CH,
Roberts WE. Angiogenesis and osteogenesis in an orthopedically expanded suture. Am J Orthod Dentofacial Orthop
1997;111:382–90.
26. Eriksen EF, Axelrod DW, Melson F. Bone Histology and
Histomorphometry. In: Bone Histomorphometry. New York:
Raven Press, 1994:33–8.
27. Storey E. Tissue response to the movement of bones. Am J
Orthod 1973;64:229–47.
28. Burstone CJ, Shafer WG. Sutural expansion by controlled
mechanical stress in the rat. J Dent Res 1959;38:534–40.
29. Miclau T, Lu C, Thompson Z, Choi P, Puttlitz C, Marcucio
R et al. Effects of delayed stabilization on fracture healing. J
Orthop Res 2007;25:1552–8.
30. Klein P, Schell H, Streitparth F, Heller M, Kassi JP,
Kandziora F et al. The initial phase of fracture healing is
specifically sensitive to mechanical conditions. J Orthop Res
2003;21:662–9.
31. Bailón-Plaza A, van der Meulen MC. Beneficial effects of
moderate, early loading and adverse effects of delayed or
excessive loading on bone healing. J Biomech 2003;36:
1069–77.
32. Claes L, Eckert-Hübner K, Augat P. The effect of mechanical stability on local vascularization and tissue differentiation in callus healing. J Orthop Res 2002;20:1099–105.
33. Mark H, Nilsson A, Nannmark U, Rydevik B. Effects of
fracture fixation stability on ossification in healing fractures.
Clin Orthop Relat Res 2004;419:245–50.
34. Rubin CT, Lanyon LE. Regulation of bone formation by
applied dynamic loads. J Bone Joint Surg Am 1984;66:
397–402.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
55
Associations between upper lip activity and
incisor position
Nihat Kilic
Department of Orthodontics, Faculty of Dentistry, Atatürk University, Erzurum, Turkey
Background: Muscle activity in the upper lip may influence the positions of the upper and lower incisors.
Objective: To determine the associations between muscle activity in the upper lip and the inclinations of the incisors, overjet
and overbite.
Methods: Forty-five subjects (29 girls, 16 boys), between 11 and 15 years of age with predominantly Class I malocclusion,
were used. The inclinations of the incisors, overjet and overbite were measured on lateral cephalometric radiographs. Bipolar
electrodes were placed on the upper lip to record the activity in orbicularis oris muscle at rest, during maximal clenching, chewing hazelnuts and swallowing. Correlation coefficients between the cephalometric variables and the electromyographic (EMG)
activity in the upper lip were calculated.
Results: There was no gender difference in the EMG activity in the upper lip. There were no statistically significant associations
between the EMG activities in the upper lip and the inclinations of the incisors, overjet and overbite.
Conclusions: The positions of the incisors do not appear to be influenced by muscle activity in the upper lip.
(Aust Orthod J 2010; 26: 56–60)
Received for publication: March 2009
Accepted: January 2010
Nihat Kilic: drnkilic@yahoo.com
Introduction
The traditional view is that facial morphology and
the positions of the incisors are determined to a large
extent by the resting posture and activity of the orofacial musculature, and in particular the lower lip.1
This view is supported by evidence that the electromyographic activities of the orbicularis oris muscles
in the lower lips of subjects with Class I, Class II
division 1 and Class II division 2 malocclusions are
associated with the inclinations of the incisors.2
However, significant associations between electromyographic activity in the lower lip musculature
and the inclinations of the incisors, overjet and overbite were not found in subjects with a normal bite or
an anterior open bite.3 Associations between muscle
activity in the upper lip and dentoalveolar morphology have not received the same attention, although
there is some evidence that the orbicularis oris muscle
in the upper lip may be active in children with an
atypical swallowing pattern and incompetent lips.4
Furthermore, some reports have suggested that
the force exerted by the upper lip may influence the
inclination of the upper incisors.5
56
Australian Orthodontic Journal Volume 26 No. 1 May 2010
The purpose of the present study is to determine if
muscle activity in the upper lip, specifically in the
orbicularis oris muscle, is associated with the inclinations of the upper and lower incisors, overjet and
overbite.
Materials and methods
The 45 subjects (29 girls, 16 boys) in this investigation were randomly selected from those with
crowding, increased or decreased overjet or overbite,
spacing, flared or retruded incisors who applied to the
Department of Orthodontics, Faculty of Dentistry,
Atatürk University for orthodontic treatment. The
mean ages of girls and boys were 13.56 ± 1.04 and
13.47 ± 0.91 years, respectively. Thirty-two subjects
had dental and skeletal Class I malocclusions, seven
subjects had Class II malocclusions and six subjects
had Class III malocclusions. The subjects had competent lips and no developmental and/or acquired
craniofacial or neuromuscular deformities, no systemic disease, no history of orthodontic treatment,
no signs or symptoms of temporomandibular joint
disorder (TMD) and no habits such as an abnormal
© Australian Society of Orthodontists Inc. 2010
ASSOCIATIONS BETWEEN UPPER LIP ACTIVITY AND INCISOR POSITIONS
U1_SN
Figure 2. Raw and integrated EMG obtained during chewing.
Overjet
Overbite
IMPA
Figure 1. Cephalometric measurements.
swallowing pattern, finger or thumb sucking. The
materials used in this study were the lateral cephalometric radiographs and EMG records of the subjects.
This study was approved by the Ethics Committee
Board of the School of Dentistry, Atatürk University,
and the parents of all subjects gave their informed
consent.
The lateral cephalometric radiographs were taken
under standardised conditions and scanned with an
Epson Expression 1860 Pro scanner (Seiko Epson
Corporation, Nagano-ken, Japan) at a magnification
of 100 per cent. Quick Ceph 2000 (Quick Ceph
Systems, San Diego, CA, USA) was used to measure
the overjet, overbite and inclinations of the upper and
lower incisors (Figure 1).
The EMG records were obtained in the Physiology
Department, Faculty of Medicine, Atatürk University.
Before each recording session, the procedure was
explained in detail to the subjects and their parents to
allay anxiety. During the EMG recording, the subjects sat in an upright and relaxed position with their
head in normal posture. Before placement of the
surface electrodes, the recording sites on the upper lip
were thoroughly cleaned with 70 per cent alcohol to
minimise electrode impedance. Bipolar surface electrodes (EL350S, Biopac System, Inc, 42 Aero
Camino, Galeta, CA, USA) were placed on either
side of the philtrum.6 The electrodes consisted of two
tin electrodes (9.5 mm diameter) embedded 30 mm
apart in a watertight acrylic bar. Conductive paste
(Sanborn Redux Electrode Paste, Hewlett Packard
Sunborn Division, Maltham, MA, USA) was applied
to the upper lip and at least 5 minutes elapsed for
the paste to moisten the surface of the skin. EMG
activity in the upper lip muscle was recorded with the
lips at rest, during maximal clenching, chewing of
two hazelnuts and swallowing of the chewed nuts. To
obtain the rest position, each subject was asked to
close her/his eyes, moisten the lips, swallow, breathe
deeply and relax their lower jaw. For maximal clenching the subjects were instructed to close their teeth in
centric occlusion as forcibly as possible. The only
instruction given to the subjects for chewing and
swallowing was to ask each subject to chew freely two
hazelnuts and then to swallow the chewed nuts. A
few trial tests were made to familiarise each subject
with the procedures before beginning an EMG
recording.
Electromyographic records were taken at rate of 5000
samples/second with maximum voltage of 10 mV.
EMG signals were band-pass filtered (10 Hz – 1 kHz)
using an A/D board (Biopac, MP100, Galeta, CA,
USA) and stored as raw EMG recordings for off-line
analysis with commercially-available software. Raw
EMGs were amplified, full-wave rectified, integrated,
and analysed (Figure 2). For each procedure, the integrated EMG was analysed over 10 seconds. All procedures were carried out with MP 100 data acquisition and analysis systems (Biopac Systems EMG100
Australian Orthodontic Journal Volume 26 No. 1 May 2010
57
KILIC
Table I. Comparisons of the cephalometric and electromyographic variables in the boys and girls.
Overjet (mm)
Overbite (mm)
U1/SN (degrees)
LI/MP (degrees)
Rest (µV)
Clenching (µV)
Chewing (µV)
Swallowing (µV)
Male
Female
Male
Female
Male
Female
Male
Female
Male
Female
Male
Female
Male
Female
Male
Female
Mean
SD
Minimum
Maximum
p
3.89
3.10
0.92
0.40
102.70
101.50
90.26
88.21
33.74
40.84
108.74
130.05
326.88
359.32
432.22
415.87
1.78
2.26
1.14
1.29
6.32
5.99
4.66
5.39
13.08
15.85
55.62
50.18
188.59
150.28
151.85
141.97
0.70
- 0.60
-1.20
-1.90
92.00
85.10
83.70
75.90
15.35
15.20
37.64
62.29
80.14
168.37
174.62
207.74
6.90
9.30
2.60
4.00
113.60
112.20
96.90
97.70
60.50
77.57
224.16
234.59
754.89
966.50
737.48
718.71
0.232
amplifiers; MP100 module; AcqKnowledge MP 100
Software version 3.0; Biopac System Inc., Galeta, CA,
USA).
Amplitudes of action potentials were determined in
microvolts (µV). The mean amplitude of the action
potential for the rest position, and the peak-to-peak
values of maximal clenching, chewing and swallowing
were used for the statistical analyses.
Statistical analysis
The gender differences in the chronological ages,
cephalometric and electromyographic variables were
compared with Student’s t-test. Pearson’s correlation
coefficient was used to determine if there were significant associations between the electromyographic
variables and the dental parameters. All statistical
analyses were performed using the SPSS software
package SPSS for Windows (Version 11.5, SPSS Inc,
Chicago, IL, USA).
Results
There was no significant difference between the mean
ages of the boys and girls (p = 0.756). The ages of the
boys ranged from 12.00 to 14.86 years (Mean age:
13.47 years) and the ages of the girls ranged from
11.08 to 15.00 years (Mean age: 13.56 years).
58
Australian Orthodontic Journal Volume 26 No. 1 May 2010
0.183
0.528
0.204
0.132
0.193
0.527
0.718
There were no significant gender differences in the
cephalometric and electromyographic variables
(Table I). Overjet in the girls was almost twice as
variable as the overjet in the boys (Coefficients
of variation: 73 per cent and 45 per cent, respectively), whereas the variability in swallowing and UI/SN
was almost identical in the boys and girls
(Coefficients of variation, Swallowing: 35 per cent,
34 per cent; UI/SN: 6.1 per cent, 5.9 per cent).
Generally, the girls showed higher activity in all EMG
parameters than the boys, but the EMG recordings in
both genders were very variable. For example, the
range of EMG values in the boys and girls during chewing were 80 – 754 µV and 168 – 966 µV,
respectively.
Associations between the cephalometric and electromyographic variables are given in Table II. The positive coefficients ranged from .005 (UI/SN and Rest)
to .286 (UI/SN and Swallowing), and the negative
coefficients ranged from -.028 (Overjet and Rest) to
-.228 (LI/MP and Rest). There was no statistically
significant correlation between the dental parameters
and electromyographic activity in the superior orbicularis oris muscle. The only coefficient to approach
statistical significance occurred between swallowing
and UI/SN (p = 0.062).
ASSOCIATIONS BETWEEN UPPER LIP ACTIVITY AND INCISOR POSITIONS
Table II. Associations between the cephalometric and electromyograph-
ic variables.
EMG
parameters
Rest
Clenching
Chewing
Swallowing
r
p
r
p
r
p
r
p
Overjet
Overbite
U1/SN
L1/MP
-.028
0.855
-.146
0.334
.030
0.844
.022
0.886
-.117
0.438
.040
0.791
-.038
0.800
-.160
0.289
.005
0.972
.212
0.156
.204
0.173
.289
0.062
-.228
0.128
.010
0.946
-.119
0.430
.033
0.826
Discussion
The present study failed to find significant associations between the electromyographic activity in
superior orbicularis oris muscle at rest, during clenching, chewing and swallowing and the positions of the
incisors. The associations were weak and no coefficient exceeded .3. The highest statistical finding
occurred between UI/SN and swallowing, but this
accounted for only 8 per cent of the variation and
while this is unlikely to be of value clinically, it does
indicate the direction for future EMG studies. The
findings on muscular activity in the upper lip during
chewing and swallowing agree with published work
and, indirectly, support the view that the upper lip
plays little part in determining the positions of the
incisors, except in subjects with an anterior open bite.7
Although electromyography was introduced to the
profession 50 years ago, the method has delivered
little of value to practicing orthodontists.8 Some
problems are the reliability and utility of recordings
made with surface electrodes, the processing of
the signal (raw versus integrated) and, in particular,
the variability in recordings from the same muscles
under apparently identical conditions.9 The method
is primarily a research tool. Providing samples are
well-defined and the recording method carried out
under tightly controlled conditions by experienced
people, the findings can indicate directions for future
research.10 The finding that the coefficient between
the inclination of the upper central incisors and the
activity in the superior orbicularis oris muscle during
swallowing approached significance suggests that the
upper lip and upper incisors need to be described in
greater detail.
One explanation for the negative findings may have
been the choice of subjects: the majority had Class I
malocclusions. The upper lip in subjects with this
malocclusion acts as a passive ‘drape,’ covering the
upper incisors at rest and during function and playing little/no part in forming an anterior oral seal. In
subjects with an increased overjet and incompetent
lips and an anterior open bite, the upper lip may contribute to the formation of an anterior oral seal with
a consequential increase in activity in the superior
orbicularis oris muscle. This view is supported by previous studies that have reported upper lip activity in
children with atypical swallowing patterns and
incompetent lips. The majority view, however, is that
the upper lip plays little part in forming an anterior
oral seal.
The computer software programme used to measure
the cephalometric radiographs had some advantages
over traditional tracings. It was possible to see the
contours of bony structures by enlarging the image
and changing the contrast when needed.11 The
reproducibility of surface EMG recording by the
MP 100 Data Acquisition and Analysis System has
been assessed previously and high interclass correlation coefficients for repeated trials were
reported.12,13
Others have reported that activity in superior orbicularis oris muscle does not appear to be correlated with
overjet, overbite and incisor inclinations, even in subjects with Class II malocclusion.3,6 But in subjects
with atypical swallowing, the orbicularis oris muscle
in the upper lip is active, presumably because it participates with the tongue in forming an anterior oral
seal.4 Significant correlations have, however, been
reported between inferior orbicularis oris muscle
activity and the positions of the incisors.2 High
amplitudes of activity in the lower lip were correlated
significantly with retroclined upper and lower incisors,
but there was no significant association between the
resting activity in the upper lip and the inclination
of the lower incisors. Recent evidence suggests that
resting pressures from the lips and tongue are not
balanced: lower lip pressure is less than tongue pressure in the mandibular incisor area, but upper lip
pressure is greater than tongue pressure in the maxillary incisor area.14 These unequal pressures may
be balanced by metabolic activity in the periodontal
ligament.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
59
KILIC
Conclusion
5.
The positions of the incisors do not appear to be
influenced by muscle activity in the upper lip at rest,
during clenching, chewing or swallowing.
6.
7.
Corresponding author
Dr Nihat Kilic
Atatürk Üniversitesi Diş Hekimliǧi Fakültesi
Ortodonti Anabilim Dalı
25240 Erzurum
Turkey
Tel:
+90 442 2311810
Fax:
+90 442 2312270 – 2360945
Email: nkilic@atauni.edu.tr - drnkilic@yahoo.com
8.
9.
10.
11.
12.
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pp.331–58.
Effects of levelling of the curve of Spee on the
proclination of mandibular incisors and expansion
of dental arches: a prospective clinical trial
Nikolaos Pandis, * Argy Polychronopoulou, † Iosif Sifakakis, + Margarita Makou + and
Theodore Eliades ±
Private practice, Corfu,* Departments of Community and Preventive Dentistry† and Orthodontics,+ School of Dentistry, University of Athens
and the Department of Orthodontics, School of Dentistry, Aristotle University of Thessaloniki,± Greece
Objectives: To investigate the effects of levelling the curve of Spee (COS) on the inclination of the mandibular incisors and the
width of the mandibular arch.
Methods: Fifty patients, 10–18 years of age, were selected using the following inclusion criteria: nonextraction treatment in the
mandibular arch; eruption of all mandibular teeth; no spaces in the mandibular arch; no crowding in the posterior mandibular
segments; a mandibular irregularity index greater than 2.5. The depth of the COS, the amount of crowding of the mandibular
anterior dentition and the intercanine and intermolar widths were measured on standardised photographs of the casts. The
inclinations of the mandibular incisors were measured on cephalometric radiographs. The paired t-test was used to analyse
changes in the intercanine and intermolar widths and incisor inclinations before and after treatment, whilst the Wilcoxon signed
ranks test was used to examine changes in the COS with treatment. The data were further analysed with a regression analysis
to determine the measurements that predicted a reduction of the curve of Spee at the 5 per cent level of significance.
Results: The COS showed a median decrease of 0.9 mm, with 50 per cent of the cases ranging between 0.4 mm and 1.4
mm. The sole predictor of curve flattening was the lower incisor to mandibular plane angle.
Conclusions: The COS is mainly ‘flattened’ by proclining the mandibular incisors. For 1 mm of levelling the mandibular incisors
were proclined 4 degrees, without increasing arch width.
(Aust Orthod J 2010; 26: 61–65)
Received for publication: August 2009
Accepted: January 2010
Nikolaos Pandis: npandis@yahoo.com
Argy Polychronolpoulou: argypoly@dent.uoa.gr
Iosif Sifakakis: isifak@gmail.gr
Margarita Makou: mmakou@dent.uoa.gr
Theodore Eliades: teliades@ath.forthnet.gr
Introduction
The curve of Spee (COS) describes the curved plane
formed by the tips of the buccal cusps of the
mandibular dentition, and it is defined as the distance
from the deepest point on the mandibular arch to the
line connecting the tip of the mesio-buccal cusp of
the lower second molar and the incisal edge of the
most extruded incisor.1 This curve was first reported
to occur in the dentitions of mammals other than
man and was first applied to the human dentition by
Ferdinand Graf von Spee in 1890.2
© Australian Society of Orthodontists Inc. 2010
The COS is flatter in deciduous dentitions than in
adult dentitions and develops with the eruption of
the mandibular first permanent molars and incisors.3,4
Once established it remains relatively stable.5,6
Differences in the times of eruption of the mandibular permanent teeth as well as variations in skeletal
morphology, sagittal jaw relationship and incisor
occlusion may affect the depth of the COS.4,7,8
An increased curve of Spee before treatment has
been associated with a low Frankfort-mandibular
plane angle, deep overbite, increased overjet and Class
Australian Orthodontic Journal Volume 26 No. 1 May 2010
61
PANDIS ET AL
Table I. Demographic and clinical characteristics of the subjects.
Variable
Mean ± SD
(Per cent)
Age (years)
Gender
13.8 ± 1.3
Male
10 (20.0)
Female
40 (80.0)
Total
50 (80.0)
Crowding (Irregularity index)
5.6 ± 2.3
Crowding
Moderate (<5.5 mm)
25 (50.0)
Severe (>5.5 mm)
25 (50.0)
Angle Class
I
30 (60.0)
II
18 (36.0)
III
2 (4.0)
Mean treatment time
2.75 ± 0.84
II molar malocclusion, but no significant gender
differences have been identified.9
The rationale behind the traditional concept of levelling the COS is somewhat obscure.10 It probably
facilitated early attempts at deep overbite correction
before effective intrusion mechanics were available.10
Andrews believed that a deep COS may make it
almost impossible to achieve a Class I canine relationship and he associated the COS with post-treatment relapse. He concluded that flattening the COS
should be an orthodontic treatment goal, even
though not all normal occlusions have flat occlusal
planes.11 A deep curve of Spee may also result in
occlusal interferences during mandibular function.12
There are two types of COS: in the first one, which is
more common in cases requiring extractions, the posterior teeth are mesially inclined and they require
space for uprighting.10 In the second type of COS, no
additional space is needed since the posterior axial
inclinations are normal. In any case, levelling of the
curve of Spee by controlled incisor intrusion and/or
molar tip-back does not affect the amount of space
required.13,14 Some authors reported a linear relationship between the depth of the curve and the space
required for levelling,14-16 but others have concluded
that the relationship is nonlinear and that a number
of factors affect this relationship, including the site of
registration of the arch circumference and the arch
form.17
An additional factor, which can affect both the
mandibular arch perimeter and arch space, is arch
expansion. Steiner and Ricketts have proposed that
62
Australian Orthodontic Journal Volume 26 No. 1 May 2010
Table II. Age distribution of the subjects.
Age
N
(Per cent)
10
12
13
14
15
16
18
1
4
18
13
10
3
1
(2)
(8)
(36)
(26)
(20)
(6)
(2)
1 mm of lower incisor advancement produces 2 mm
of arch length.18,19 Also, 1 mm of canine expansion
produces 1 mm of arch space, 1 mm of molar expansion results in only 0.25 mm increase in arch length
and 2 mm per side of arch length is gained by molar
uprighting.18 Germane et al.,20 used a mathematical
model to demonstrate that a 5 mm increase in arch
length required approximately 5 mm of lateral expansion or 4 mm of incisor advancement. It was also
discovered that wide dental arches produce more
arch length per millimetre of expansion compared to
narrow arches.20
Currently, there is a lack of evidence of the extent of
proclination of mandibular incisors and the expansion of the mandibular dental arch associated with
levelling of the curve of Spee with a straight-wire
appliance. Therefore, the objective of this prospective
study was to investigate the effects of levelling the
curve of Spee on the proclination of mandibular
incisors and dental arch expansion.
Sample and methods
Fifty patients, 10–18 years of age, were included in
this prospective study. The participants were selected
from a large pool of patients using the following
inclusion criteria: nonextraction treatment in the
mandible; eruption of all mandibular teeth; no spaces
in the mandibular arch; no crowding in the posterior
mandibular segments; a mandibular irregularity
index greater than 2.5. The basic demographic and
clinical characteristics of the sample are shown in
Table I. Table II depicts distribution of the patients in
each age group.
CURVE OF SPEE AND MANDIBULAR INCISOR PROCLINATION
Table III. Cephalometric and cast characteristics at baseline and after
treatment in all subjects (N = 50).
Measurement
Incisor inclination
L1-MP (degrees)
L1-NB (degrees)
L1-APog (degrees)
Intercanine width (mm)
Intermolar width (mm)
Spee curve (mm)
Baseline
Mean ± SD
92.3
25.1
23.5
25.4
44.1
2.0
±
±
±
±
±
±
6.8
5.9
4.6
1.8
2.6
0.5
After treatment
Mean ± SD
96.8
29.8
28.8
27.1
45.8
1.0
±
±
±
±
±
±
7.6
5.9
4.6
1.3
1.9
0.4
p
<10-3
<10-3
<10-3
<10-3
<10-3
<10-3+
L1-MP: Mandibular incisor to mandibular plane
L1-NB: Mandibular incisor to nasion-point B line
L1-APog: Mandibular incisor to point A-pogonion line
p value for comparison of baseline and post-treatment measurements
based on paired t-test
+p value for comparison of baseline and post-treatment measurements
based on the Wilcoxon signed rank test
All patients were bonded with a 0.022 inch slot edgewise appliance and the lower arch was levelled using a
straight-wire appliance. The wire sequence was as
follows: 0.014 or 0.016 ideal form Sentalloy (GAC,
Central Islip, NY, USA), followed by 0.020 inch ideal
form Sentalloy, 0.020 inch stainless steel wire and
0.018 x 0.025 inch stainless steel wire. Brackets were
bonded at a standard height on each tooth using a
bracket-positioning gauge (Ormco, Glendora, CA,
USA).
Bracket bonding, archwire placement and all treatment stages were performed by the first author.
Complete records were obtained before and at the
end of treatment, and the amount of crowding of the
mandibular anterior teeth was assessed on dental casts
using the irregularity index, measured with a fine-tip
digital caliper, (Mitutoyo Digimatic NTD12-6” C,
Mitutoyo Corporation, Japan). Changes in the intercanine and intermolar widths were also measured on
the dental casts using the cusp tips of the lower
canines and the central grooves in the lower molars as
reference points. The same archwire sequence was
used for all subjects, and all subjects were recalled at
4–8 week intervals.
Pre- and post-treatment lateral cephalograms were
traced by the same person. The inclinations of the
mandibular incisors were assessed with the following
angular measurements: lower incisor to mandibular
plane (L1-MP); lower incisor to N-B line (L1-NB);
Figure 1. The depth of the COS was measured on digital images of the
initial and final models.
and lower incisor to the A-Pog line (L1-APog). The
COS was measured on standardised pre- and posttreatment photographs of the casts. Both sides of the
models were photographed (Figure 1). The resultant
digital images were entered into a cephalometric software programme (Viewbox 4.0, Dhal, Greece) and
the depth of the COS was measured using the second
molars and incisors as reference points. The means of
the right and left side measurements were used in all
subsequent calculations. The radiographs and the
models were measured in a random order to blind the
investigator and reduce observer bias.
To assess the intra-examiner reliability, seven models
and seven cephalometric radiographs were randomly selected from the records. The radiographs
were re-traced and the measurements repeated.
Additionally, the intercanine and intermolar widths
were remeasured on the casts. The reproducibility of
the measurements was investigated with a paired
t-test analysis for each variable. The analysis revealed
no statistical significance between the first and second
measurements (p > 0.05).
Descriptive statistics for the study sample, clinical
characteristics, cast and cephalometric data were calculated. Paired t-tests were used to analyse changes in
intercanine and intermolar widths and incisor inclinations before and after treatment, and the Wilcoxon
signed rank test was used to compare the change in
the COS before and after treatment. A regression
analysis determined the characteristics/measurements
that could be used to predict a reduction in the COS.
Incisor inclination, intercanine width, intermolar
width and the clinical and demographic characteristics were used in a multiple median regression model
and non-significant variables were deleted by backward elimination (Deletion criterion, p > 0.05). A
p < 0.05 was considered to be statistically significant.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
63
PANDIS ET AL
All the analyses were conducted with the STATA 10.1
statistical package (StataCorp LP, Houston, TX,
USA).
Results
Table III gives the cephalometric and cast characteristics at baseline and after treatment in the subjects. As
shown, the inclinations of the incisors and the intercanine and intermolar widths increased. The COS
showed a median decrease of 0.9 mm, with 50 per
cent of the cases ranging between 0.4 mm and 1.4
mm and a slight expansion of the buccal segments
(Mean value: 1.7 mm). On average, a 4 degree proclination of the mandibular incisors resulted in 1 mm
levelling in the COS. In the regression analysis only
the baseline L1-MP angular measurement was found
to be a significant predictor of the COS levelling
(p < 0.01). The data for this finding are not shown.
Discussion
Levelling of the COS is accomplished by molar
uprighting, premolar eruption, incisor intrusion and
incisor flaring or a combination of the above.21 It
seems that expansion may generate arch space in
crowded arches, however, most levelling of the COS
with a straight-wire appliance was accomplished by
the extrusion of the premolars.22 In agreement with a
recent study, which showed a marginally significant
post-treatment increase in the mandibular intercanine width in Class II division 1 deep bite cases, we
found a small, but insignificant, increase in arch
width.23 The authors attributed their finding to normal
physiologic changes that occur with increasing age.23
We found that levelling of the COS with a straightwire appliance correlated well with proclination of
the mandibular incisors measured as an increase in
the mandibular incisor to MP line angle. Whilst
other changes, such as an increase in both the intercanine and intermolar widths, accompanied levelling
of the curve, they were found to be coincidental and
not correlated with the actual levelling of the
mandibular arch.
Although many studies evaluating the amount of
space required to correct 1 mm of the COS have indicated that the relationship is not one-to-one, some
authors have ignored their own evidence and proposed formulae to ‘accurately’ predict the space
required to level the COS.14-16 For example, Baldridge
suggested the following formula for the accurate pre64
Australian Orthodontic Journal Volume 26 No. 1 May 2010
diction of the required space Y = 0.488 X - .51, where
Y = arch length differential in millimetres, X = sum of
right and left side maximum depths of the COS in
millimetres.15 Similar formulae have been developed
by Garcia (Y = 0.657 X + 1.34) and Braun (Y = 0.2462
X - 0.1723).14,16 On the other hand, Germaine et al.
found that the relation between the levelling of the
COS and the space required did not follow a linear
relationship and it was dependent on arch form and
the depth of the COS.22 They also showed that under
most circumstances, less than 1 mm of space was
required to level 1 mm of Spee.17
In crowded mandibular arches with a deep COS, the
space required to level the curve should be considered
in the treatment planning and may indicate a need
for extractions. A case with 5 mm of crowding with a
flat COS may be treated differently from a case with
similar crowding, but with a 3 mm of COS, because
proclination of mandibular incisors in the latter case
could predispose the incisors to periodontal complications. In the opinion of one author the most effective means of alleviating crowding is combined incisor proclination and canine expansion.20
There is no general agreement as to the most appropriate biomechanical principles that should be used
to accomplish stable, long-term levelling of the
mandibular arch. There is no difference in the relapse
of a corrected COS between extraction and nonextraction cases,21,24 although in 16 per cent of cases
the return of the COS was accompanied by an
increase in the overbite.21 Recent evidence suggests that the amount of relapse of the COS is not
correlated with the initial depth of the curve.23,25
Relapse in the COS does not appear to be correlated
with degree of the COS levelling during treatment.
Some investigators consider that there is a higher
incidence and magnitude of COS relapse if the COS
is not completely reduced during treatment.23,26 But
the evidence is by no means clear-cut: De Praeter
et al. reported there was no such correlation between
the degree of levelling and relapse.25 There is also
some evidence that the contrary may be true: the
more the COS is levelled during treatment the more
it will relapse after treatment.21,22 The explanation of
these conflicting results lies in the differences between
these studies, in particular the axial inclinations of the
posterior teeth and the mechanisms of arch levelling.
Indiscriminate levelling in the mandibular arch can
produce undesirable side effects, including posterior
CURVE OF SPEE AND MANDIBULAR INCISOR PROCLINATION
rotation of the mandible. Building in some occlusal
curvature could be desirable for both aesthetics and
function.10 A recent study concluded that a curve
depth of 1.9 mm at the end of the treatment might
result in higher stability, since these cases were associated with the least amount of post-treatment
change.24 Moreover, uncontrolled arch levelling with
continuous archwires containing a reverse COS
should be avoided, especially beyond the stage at
which the occlusal plane is flat. After this stage, these
wires produce excessive incisor tipping resulting from
intrusive forces at the incisor brackets.14,27 Further
investigation is required of COS levelling in different
facial types and its effect on mandibular rotation.
Conclusion
8.
9.
10.
11.
12.
13.
14.
15.
Flattening of the COS is mostly achieved by proclination of the mandibular incisors. On average, a
4 degree proclination of the mandibular incisors
results in 1 mm levelling of the COS. Only the
L1-MP angular measurement was found to be a
significant predictor of the COS levelling.
16.
Corresponding author
19.
Dr Theodore Eliades
57 Agnoston Hiroon Str
Nea Ionia GR-14231
Greece
Email: teliades@ath.forthnet.gr
References
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2.
3.
4.
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7.
Hitchcock HP. The curve of Spee in Stone Age man. Am J
Orthod 1983;84:248–53.
Spee FG. Die Verschiebungsbahn des Unterkiefers am
Schadel. Archives fur Anatomic und Physiologie. Leipzieg:
Verlag Veitund Comp., 1890:285–93.
Ash MM. Wheeler’s dental anatomy, physiology and occlusion. Philadelphia: WB Saunders, 1993:151.
Marshall SD, Caspersen M, Hardinger RR, Franciscus RG,
Aquilino SA, Southard TE. Development of the curve of
Spee. Am J Orthod Dentofacial Orthop 2008;134:344–52.
Carter GA, McNamara JA Jr. Longitudinal dental arch
changes in adults. Am J Orthod Dentofacial Orthop 1998;
114:88–99.
Bishara SE, Jakobsen JR, Treder JE, Stasi MJ. Changes in the
maxillary and mandibular tooth size-arch length relationshipfrom early adolescence to early adulthood. Am J Orthod
Dentofacial Orthop 1989;95:46–59.
Farella M, Michelotti A, van Eijden TMGJ, Martina R. The
curve of Spee and craniofacial morphology: a multiple
regression analysis. Eur J Oral Sci 2002;110:277–81.
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Cheon SH, Park YH, Paik KS, Ahn SJ, Hayashi K,Yi WJ,
Lee SP. Relationship between the curve of Spee and dentofacial morphology evaluated with a 3-dimensional reconstruction method in Korean adults. Am J Orthod Dentof
Orthop 2008;133:640.e7–14.
Xu H, Suzuki T, Muronoi M, Ooya K. An evaluation of the
curve of Spee in the maxilla and mandible of human permanent healthy dentitions. J Prosthet Dent 2004;92:536–9.
Burstone JC, Marcotte MR. Problem solving in Orthodontics
– Goal oriented treatment strategies. 1st edn. Chicago:
Quintessence, 2000:40:181–3.
Andrews FL. The six keys to normal occlusion. Am J Orthod
1972;62:296–309.
Dawson P. Evaluation, diagnosis and treatment of occlusal
problems. St. Louis: CV Mosby, 1974.
Woods M. A reassessment of space requirements for lower
arch leveling. J Clin Orthod 1986;20:770–8.
Braun S, Hnat WP, Johnson BE. The curve of Spee revisited.
Am J Orthod Dentofacial Orthop 1996;110:206–10.
Baldridge DW. Leveling the curve of Spee: its effect on
mandibular arch lengths. J Pract Orthod 1969;3:26–41.
Garcia R. Leveling the curve of Spee: a new prediction
formula. J Charles H Tweed Int Found 1985;13:65–72.
Germane N, Staggers JA, Rubinstein L, Revere JT. Arch
length considerations due to the curve of Spee: a mathematical model. Am J Orthod Dentofacial Orthop 1992;102:
251–5.
Ricketts R M, Bench RW, Gugino CF, Hilgers JJ, Schulhof
RJ. Bioprogressive Therapy. Denver: Rocky Mountain/
Orthodontics, 1979:115–6, 143–4.
Steiner CC. The use of cephalometrics as an aid to planning
and assessing orthodontic treatment: Report of a case. Am J
Orthod 1960;46:721–35.
Germane N, Lindauer SJ, Rubenstein LK, Revere JH,
Isaacson RJ. Increase in arch perimeter due to orthodontic
expansion. Am J Orthod Dentofacial Orthop 1991;100:
421–7.
Shannon KR, Nanda RS. Changes in the curve of Spee with
treatment and at 2 years posttreatment. Am J Orthod
Dentofacial Orthop 2004;125:589–96.
Bernstein RL, Preston CB, Lampasso J. Leveling the curve of
Spee with a continuous archwire technique: a long term
cephalometric study. Am J Orthod Dentofacial Orthop
2007;131:363–71.
Carcara S, Preston C B, Jureyda O. The relationship
between the curve of Spee, relapse, and the Alexander
discipline. Semin Orthod 2001;7:90–9.
Lie F, Kuitert R, Zentner A. Post-treatment development of
the curve of Spee. Eur J Orthod 2006;28:262–8.
De Praeter J, Dermaut L, Martens G, Kuijpers-Jagtman AM.
Long-term stability of the leveling of the curve of Spee. Am
J Orthod Dentofacial Orthop 2002;121:266–72.
Preston CB, Maggard MB, Lampasso J, Chalabi O. Longterm effectiveness of the continuous and the sectional archwire techniques in leveling the curve of Spee. Am J Orthod
Dentofacial Orthop 2008;133:550–5.
Ferguson JW. Lower incisor torque-the effects of rectangular
archwires with a reverse curve of Spee. Br J Orthod 1990;
17:311–15.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
65
A comparison of dental changes produced by
mandibular advancement splints in the
management of obstructive sleep apnoea
Hui Ching Ang and Craig Dreyer
School of Dentistry, The University of Adelaide, Adelaide, Australia
Background: Mandibular advancement splints (MAS) are a recognised and popular treatment option for obstructive sleep
apnoea (OSA) due to their simplicity, tolerance and non-invasiveness.
Objectives: To investigate and compare the dental changes associated with the use of monoblock and duoblock appliances.
Methods: Fifty-two pretreatment and follow-up study models of patients from a public hospital and private dental clinic were
assessed. Seventeen subjects used a soft elastomeric monoblock appliance (MB), 29 subjects used a hard acrylic duoblock
(DB) and six subjects wore a monoblock followed by a duoblock appliance (MB-DB). Measurements of dental and arch
changes were obtained and analysed on study models and standardised bitewing radiographs.
Results: A statistically significant reduction was observed in the maxillary intercanine distance in all splint categories, with DB
users showing the greatest decrease (p < 0.05). The change in the mandibular intercanine distances differed according to
splint categories (p < 0.05). MB and MB-DB patients demonstrated a decrease in this measurement variable, whereas an
increase was seen in DB users. A statistically significant increase in the mandibular intermolar distance was also observed in all
splint categories (p < 0.05), with DB users showing the greatest increase.
Conclusions: Both MB and DB appliance systems produced similar, but mild dental effects. No particular appliance can be
recommended and the choice of appliance should be considered on a case-by-case basis.
(Aust Orthod J 2010; 26: 66–72)
Received for publication: June 2009
Accepted: March 2010
Hui Ching Ang: cori.ang@gmail.com
Craig Dreyer: craig.dreyer@adelaide.edu.au
Introduction
Obstructive sleep apnoea (OSA) is a chronic medical
condition characterised by repetitive episodes of
upper airway collapse during sleep which results in
apnoeic and hypopnoeic episodes, despite persistent
thoracic and abdominal respiratory effort.1 OSA is a
significant and heavy burden on society, not only in a
financial sense, but also from the aspect of health
morbidity. It is estimated that six per cent of the
Australian population (i.e. over 1.2 million people)
experience sleep disorders, the most common of
which is OSA.2
Therapeutic options to manage this condition
include conservative measures, continuous positive
airway pressure (CPAP)3–5 and surgery.6 The conservative management of OSA includes the use of oral
66
Australian Orthodontic Journal Volume 26 No. 1 May 2010
appliances, the most common of which is the
mandibular advancement splint (MAS) that could be
of one-piece design (monoblock) or of two pieces
(duoblock).7 The one-piece design fixes the mandible rigidly in a forward position, while a two-piece
MAS allows some mandibular movement and the
possibility of further mandibular advancement.7,8
Previous studies have investigated the dental effects of
either the monoblock or the duoblock systems.9–15
There has yet to be a comprehensive study comparing
the arch changes associated with both splints, which
may influence the clinician’s decision when selecting
an appropriate splint for the patient. We aimed to
investigate the dental changes associated with the use
of both splints and to compare the extent of changes
between both systems.
© Australian Society of Orthodontists Inc. 2010
DENTAL CHANGES FROM MANDIBULAR ADVANCEMENT SPLINTS
Figure 1. Monoblock appliance.
Figure 2. Twinblock appliance.
Figure 3. Positioning of the modified Snapex film holder on the study model.
Figure 4. Positioning the cone for a radiograph.
Materials and methods
51 years; Range: 30 to 73 years) wore hard acrylic
duoblock appliances (Figure 2); and six subjects
(Mean age: 45 years; Range: 25 to 60 years) wore a
monoblock followed by a duoblock appliance
(MB-DB).
The study was designed as a prospective, crosssectional examination of study models of OSA subjects from an institution and a private dental clinic.
The following inclusion criteria were applied:
1) Subjects with maxillary and mandibular first
permanent molars and canines.
2) Subjects who had worn a MAS continuously (minimum of five to six hours per night) for at least 6
months.
Of the 191 subjects who fulfilled the inclusion criteria, only 52 (17 females, 35 males) attended for
review. Of these: 17 subjects (Mean age: 47 years;
Range: 32 to 72 years) wore soft elastomeric monoblock appliances (Figure 1); 29 subjects (Mean age:
At recall, repeat study models were taken using alginate impression material and a bite registration was
taken with softened brown wax. Pretreatment and
follow-up study models were articulated in the intercuspal position on a Dentatus adjustable articulator.
Measurements were made on the articulated study
models using electronic digital calipers to 0.01 mm.
Vertical changes were measured directly on standardised bitewing radiographs using the digital calipers.
Liquid barium was painted on the cusp tips of the
Australian Orthodontic Journal Volume 26 No. 1 May 2010
67
Maxillary intercanine distance (mm)
ANG AND DREYER
Maxillary intercanine distance (mm)
Figure 5. Example of radiographs taken to measure the posterior open bite.
34
MS1
33
MS2
32
MS3
31
FS1
30
FS2
FS3
29
0
50
100 150 200 250 300 350 400
Time (weeks)
Figure 7. Mean value changes for the mandibular intercanine distance
following treatment using the 3 MAS systems.
MS1: Males using monoblock appliance
MS2: Males using twinblock appliance
MS3: Males using a monoblock followed by a twinblock appliance
FS1: Females using monoblock appliance
FS2: Females using twinblock appliance
FS3: Females using a monoblock followed by a twinblock appliance
35
34
MS1
33
MS2
32
MS3
31
FS1
30
FS2
FS3
29
0
50 100 150 200 250 300 350 400
Time (weeks)
Figure 6. Mean value changes for the maxillary intercanine distance
following treatment using the 3 MAS systems.
MS1: Males using monoblock appliance
MS2: Males using twinblock appliance
MS3: Males using a monoblock followed by a twinblock appliance
FS1: Females using monoblock appliance
FS2: Females using twinblock appliance
FS3: Females using a monoblock followed by a twinblock appliance
plaster first molars which produced a fine radiopaque
line to facilitate measurement. The bitewing films
were held in position on the articulated models with
a modified Snapex (Dentsply Pty Ltd., Mt. Waverley,
Victoria, Australia) film holder. A customised flat
metal ruler was placed on the occlusal surface of the
mandibular first molars as a horizontal guide plane
for the positioning the Snapex holder and radiographic machine cone (Figures 3 and 4). A metal wire
attached to the Snapex holder, acted as a radiographic
horizontal reference line (Figure 5).
Ten per cent (5 pretreatment, 5 follow-up) of the
models were remeasured and assessed using a paired
t-test and Dahlberg statistics to determine the presence
of systematic and random errors.
68
35
Australian Orthodontic Journal Volume 26 No. 1 May 2010
The data were analysed using linear models and were
first adjusted for a number of effects a priori, using
the following models: variable prior to treatment =
cast material + maxillary tooth number + mandibular
tooth number + error; variable at the follow-up
assessment (while still undergoing treatment) = cast
material x operator + maxillary tooth number +
mandibular tooth number. Appliance material and
operator were class variables and tooth number was a
covariate. Subsequent analysis of predicted values was
then undertaken using the fixed linear model:
variable = gender + age + time + gender x time + age
x time + splint x time + error. Gender and splint type
were class variables, age was a covariate, and treatment duration was a continuous measure of repetition modelled using a spatial covariance structure
(sp[pow]). Least squares variable estimates were
derived for each gender by splint type combination
and plotted against the maximum duration of treatment to construct graphs illustrating the significant
model effects.
Results
None of the paired t-tests comparing 10 per cent of
the models with repeat measurements showed a significant difference (p > 0.05), indicating that there
were no systematic errors due to the equipment used
in the study. The random experimental error was less
than 10 per cent of the observed population variation
for all measured variables, which suggested that the
measurement approach had little influence.
DENTAL CHANGES FROM MANDIBULAR ADVANCEMENT SPLINTS
Table I. Study model measurements, expressed values are the follow-up minus the pretreatment measurements.
Variables
Combined (N = 52)
Mean
SD
p
MB (N = 17)
Mean
SD
DB (N = 29)
Mean
SD
Mean
MB-DB (N = 6)
SD
p
Maxillo-mandibular relationship
Left posterior open bite (mm)a
Right posterior open bite (mm)a
Overbite (mm)
Overjet (mm)
Left canine relationship (mm)b
Right canine relationship (mm)b
Left molar relationship (mm)b
Right molar relationship (mm)b
1.4
1.0
-1.4
-1.1
-1.1
-0.6
-1.5
-1.3
0.9
1.2
1.2
1.7
1.5
1.4
1.7
1.8
0.05
0.13
0.08
0.00
0.03
0.73
0.02
0.30
1.4
1.0
-1.3
-0.9
-0.7
0.1
-1.5
-0.8
1.0
1.1
1.2
1.4
1.5
1.5
1.6
1.5
1.4
1.1
0.3
-0.8
-1.1
-1.1
-1.3
-1.2
0.8
1.2
0.5
1.1
1.3
1.0
1.4
1.3
1.9
1.2
-2.5
-2.2
-1.4
-0.4
-1.5
-1.3
1.0
1.1
1.5
1.3
1.5
1.7
2.2
2.2
0.24
0.11
0.31
0.03
0.38
0.42
0.00
0.15
Maxillary arch
Intercanine distance (mm)c
Intermolar distance (mm)c
Arch length (mm)c
Arch depth (mm)c
0.0
0.1
-1.3
0.1
0.4
0.6
2.0
0.7
0.52
0.90
0.26
0.54
0.2
0.3
-1.1
-0.1
0.5
0.4
1.3
0.7
-0.1
0.0
-0.8
0.3
0.4
0.6
1.8
0.8
0.0
0.0
-4.6
-0.2
0.4
0.9
1.3
0.5
0.03
0.48
0.14
0.84
Mandibular arch
Intercanine distance (mm)c
Intermolar distance (mm)c
Arch length (mm)c
Arch depth (mm)c
0.1
0.3
0.4
-0.1
0.6
0.9
1.4
0.7
0.44
0.17
0.65
0.95
0.0
0.1
0.0
-0.2
0.4
0.5
0.9
0.9
0.0
0.3
0.7
-0.2
0.7
1.1
1.4
0.6
0.3
0.9
1.3
0.0
0.5
0.3
1.1
0.4
0.00
0.01
0.11
0.47
Significant values in bold
a Means calculated from scores: overbite = -1, cusp-to-cusp relationship = 0, open bite = +1
b Means calculated from scores: Class I = 0, Class II = +1, Class III = –1
c Means calculated from scores: decrease = –1, no change = 0, increase = +1
Subjectively, subjects in general coped well with their
appliances and reported a reduction in sleep apnoea
symptoms. Repeat polysomnograph tests were conducted for most subjects and indicated successful
control of OSA by the appliances.
Prior to treatment, a normal bilateral posterior overbite was observed for all subjects. At recall, all subjects
had bilateral posterior open bites attributed to the
appliances. Changes in the left side posterior open
bite approached significance as treatment duration
increased (p = 0.05), while changes in the right
posterior open bite were not statistically significant.
A significantly greater decrease in overjet was
observed in MB and MB-DB subjects compared with
the DB subjects (p < 0.05). There was a tendency for
anterior overbite to decrease with the length of time
the appliances were worn (p = 0.08). However, there
were no apparent statistically significant differences
between splint categories.
With treatment, a mesial shift of the mandibular
canine relative to the maxillary canine and first
premolar was observed in all patients, resulting in
bilateral changes to the canine relationships. Changes
in the canine relationships on the left side were statistically significant (p < 0.05) for all splint categories.
In comparison, changes to the right canine relationship were not statistically significant.
A mesial shift of the mandibular molar relative to the
maxillary molar was also noted, causing a bilateral
change in the molar relationships. The shift was
significantly different between splint categories
(p < 0.05) for the left molar relationship, with MB
and MB-DB users having greater change compared
with DB users. In contrast, changes to the right molar
relationship were not statistically significant.
The maxillary intercanine distance decreased with
appliance wear. The decrease was statistically significant between splint categories (p < 0.05), with DB
Australian Orthodontic Journal Volume 26 No. 1 May 2010
69
ANG AND DREYER
users experiencing the greatest decrease (Figure 6). In
comparison, MB and MB-DB and users had less
change.
Changes in the mandibular intercanine distance were
statistically significant between splint categories over
time (p < 0.05). MB and MB-DB users experienced a
reduction in mandibular intercanine distance, with a
greater decrease apparent in MB users (Figure 7). In
contrast, mandibular intercanine distance remained
stable or increased slightly for all DB users.
The maxillary and mandibular intermolar distances
also increased as treatment progressed. This change
was statistically significant between splint categories
(p < 0.05) for the mandibular intermolar distance,
with all DB patients experiencing the greatest
increase in comparison with MB and MB-DB users.
In comparison, the increase in maxillary intermolar
distance was not statistically significant between
splint categories. A trend was observed such that the
increase in maxillary intermolar distance was greatest
in DB subjects.
Discussion
Previous long-term cephalometric and study model
investigations have indicated that extended use of
MAS is associated with dentofacial changes.9,10,12,15,16
The orthodontic effects of the MAS observed in
adults differ from functional appliances used in growing children in which a dentoskeletal growth alteration is desired.9 While skeletal changes noted often
involved a rotation and/or transposition of the
mandible,17–19 other studies have reported changes in
overbite and overjet, arch widths, and the canine and
molar relationships.9,10,15,16 However there has been
no comparative study which has examined the side
effects of various MAS appliances. This may be important for the clinician when selecting an appropriate
appliance for a patient. This study therefore aimed to
investigate the dental changes associated with the use
of MB and DB appliances and to compare the extent
of the changes induced by both appliances.
MAS-induced posterior open bite is a variable that is
not commonly assessed in OSA studies. In the present study, standardised bitewing radiographs of the
study models were taken, enabling the measurement
of the posterior open bite. Barium liquid provided an
excellent radiopaque marker because it produced a
thin layer on study models from which accurate
70
Australian Orthodontic Journal Volume 26 No. 1 May 2010
measurements could be made. Anatomical anomalies,
such as mandibular tori, which prevented optimal
positioning of the Snapex film holder were the same
for each patient. The potential radiographic magnification did not influence the difference (delta value)
between the pretreatment and follow-up measurements and did not therefore affect statistical
assessment of the variables.
A recent paper by Chen et al.20 used a 3-dimensional
computerised analysis system to accurately measure
conventional variables such as overbite and overjet,
and to enable the measurement of formerly
unassessed variables such as the posterior open bite.
The reference points Chen and coworkers used to
measure the posterior open bite were similar to the
points we used.
The present study, as well as other studies,10,12,15
demonstrated bilateral changes to the canine and
molar relationships following MAS wear. However,
changes in the left canine and molar relationships
were statistically significant, while changes to the
right side were not. Almeida and colleagues similarly
observed a more significant mesial shift of the left
mandibular molar.21 These authors in their angled
force theory suggested that the right side of the
mandible was the preferred chewing side and this
displaced the right condyle. Therefore, the resultant force from the MAS on the teeth was directed
anteriorly and to the left.
In contrast to the present study, Almeida and colleagues reported a greater change in the right canine
relationship.21 This variation may be attributed to
dentoalveolar changes associated with longer durations of treatment. The study by Almeida and associates reported dentoalveolar changes following a mean
treatment duration of 7.4 years. In comparison, the
present study (mean of 3.6 years) suggested changes
in the positioning of the mandible as the maxillary
and mandibular arch lengths remained stable
throughout treatment.
The decrease in the maxillary and mandibular intercanine distances in the present study may possibly be
due to a change in the forces exerted by the intra-oral
and extra-oral musculature. As the mandible is postured forward during the day due to the nocturnallyinduced mandibular advancement,19,21–23 a change in
tongue position9 occurs. This may cause an imbalance
of forces, leading to a greater influence of the extra-
DENTAL CHANGES FROM MANDIBULAR ADVANCEMENT SPLINTS
oral facial musculature compared to intra-oral
musculature (i.e. tongue) on the canines. Palatal or
lingual movements of the canines follow, resulting in
reductions in the maxillary and mandibular intercanine distance.
Similarly, the force differential between the intra-oral
and extra-oral musculature may also explain the
increase in the mandibular intermolar distance, possibly from buccal movement of the mandibular molars.
This buccal movement may be further encouraged
due to reduced occlusal contact between opposing
molars, which occurs as the posterior open bite develops over time.9
A major difference between MB and DB appliances
was that the DB caused an overall increase in
mandibular arch width (mandibular intercanine and
intermolar distances),9,10 while the MB appliance was
associated with a reduction in mandibular intercanine
distance, but an increase in mandibular intermolar
distance.12,15 Even within the MB category, there
were statistically significant differences in the
mandibular intermolar distances between the hard
acrylic and soft elastomeric appliances.12 The variation in findings suggests that differences in appliance
design may have an effect on the distribution of
forces affecting the alignment of the teeth. The disparity in design and material of the MAS used in the
current study is possibly an important factor, which
may account for the differences in mandibular arch
width changes. The MB appliance in the current
study was made of soft elastomeric material with a
greater alveolar coverage, while the hard acrylic DB
did not have any alveolar coverage. Alveolar coverage
has been suggested to affect the force vectors on the
dental arches.12 The type of occlusal splint material
used has been shown to affect the nocturnal activity
of the masticatory muscles; muscle activity is
decreased in 80 per cent of hard splint users, but
increased in 50 per cent of those using soft splints.24
It is possible that the hard DB and soft MB appliances, also used nocturnally in the present study, may
lead to similar patterns in masticatory muscle activity. It is unclear how masticatory muscle activity may
affect the mandibular arch width and this would
benefit from further investigation.
There were limitations associated with the study
which require future consideration. Because there was
no objective measure of appliance wear, the patients’
reporting of wear was relied upon. In addition,
because of the long time scale (43 to 414 weeks), it
was not possible to split the samples into two or three
time groups for comparison. Doing so would have
rendered group numbers too small for informative
statistical assessment. Furthermore, it was difficult to
perform any meaningful comparisons of mandibular
advancement because data were not available for all
subjects, and, had the combined MB-DB group been
removed from the sample, it would have resulted in a
reduction in statistical power. Future investigations
should ideally include cephalometric measurements
in conjunction with study model assessments to provide a better understanding of the dental changes
associated with MAS.
Conclusions
A comparison of dental changes produced by the MB
and DB appliance systems is important to aid the
clinician in selecting an effective device that has minimal dental side effects. The present study indicated
several statistically significant observations, including
changes in the intercanine and intermolar distances
which may possibly be explained by a daytime imbalance of forces between the intra-oral and extra-oral
musculature due to nocturnally-induced mandibular
advancement. A major difference between MB and
DB appliances was that the DB caused an overall
increase in mandibular intercanine and intermolar
distances,9,10 while the MB appliance was associated
with a reduction in mandibular intercanine distance,
but an increase in mandibular intermolar distance.12,15
The variation in findings suggests that differences in
appliance design (splint material, alveolar coverage)
may have an effect on the distribution of forces
affecting the alignment of the teeth.
While some of the orthodontic measurements
demonstrated trends towards differences between the
monoblock and duoblock systems, these were not significantly different. This indicates that both appliances
may be used safely as they both produced similar, but
mild, effects, and no particular recommendation can
be made regarding the choice of appliance.
Acknowledgments
The authors would like to thank Dr Norm Vowles for
assisting with the data collection, and Dr Toby
Hughes for his help with the statistical analysis.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
71
ANG AND DREYER
Corresponding author
Dr Craig Dreyer
School of Dentistry
The University of Adelaide
Adelaide SA 5005
Australia
Tel: (+61 8) 8303 3299
Fax: (+61 8) 8303 3444
Email: craig.dreyer@adelaide.edu.au
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12. Marklund M, Franklin KA, Persson M. Orthodontic sideeffects of mandibular advancement devices during treatment
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changes during mandibular advancement splint therapy in
sleep disordered patients. Eur J Orthod 2003;25:371–6.
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Does ozone water affect the bond strengths of
orthodontic brackets?
Matheus Melo Pithon and Rogerio Lacerda dos Santos
Faculty of Dentistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
Background: Ozone water can be used to eliminate micro-organisms from the water systems in dental offices.
Objectives: To determine if ozone water diminishes the bond strength of orthodontic adhesives.
Methods: One hundred and twenty bovine mandibular incisors were randomly divided into four equal groups. The teeth were
cleaned with pumice and washed either with tap water (Groups 1 and 3) or with ozone water Groups (2 and 4) before
bonding stainless steel orthodontics brackets to the teeth with either a composite resin (Groups 1 and 2; Transbond XT, 3M
Unitek, Monrovia, CA, USA) or a resin-modified glass ionomer cement (Groups 3 and 4; Fuji Ortho LC, GC America
Corporation, Tokyo, Japan). The manufacturers’ recommendations for bonding were followed. All samples were subjected to
thermal cycling and the shear bond strengths were determined with a universal testing machine. The Adhesive Remnant Index
(ARI) was used to score the amount of resin remaining on the teeth after debonding the brackets.
Results: There were no statistical differences in the shear bond strengths of the brackets debonded from enamel washed with
either ozone water or tap water or between the groups bonded with the two adhesive resins (p = 0.595). The ARIs in Groups
2 and 3 were significantly different from the ARIs in Groups 3 and 4 (p = 0.030).
Conclusion: Ozone water did not alter the bond strength of brackets bonded with composite resins, but it did alter the sites of
resin fracture when Fuji Ortho LC was used.
(Aust Orthod J 2010; 26: 73–77)
Received for publication: August 2009
Accepted: February 2010
Matheus Pithon: matheuspithon@col.com.br
Rogerio Lacerda dos Santos: laceraorto@hotmail.com
Introduction
Ozone water, which contains three times more
oxygen than tap water, has been used to disinfect the
water systems in dental units.1–3 Ozone is thought to
penetrate the cell and oxidise intracellular amino and
nucleic acids.2 Cellular lysis depends to some extent
on the severity of these reactions.4,5 The polymerisation and bond strengths of orthodontic adhesives
used on teeth washed with ozone water may be affected
by the high concentration of oxygen. We aim to
determine if post-prophylaxis washing of bovine
enamel with ozone water affects the bond strengths
and sites of failure of orthodontic brackets bonded
with different adhesives systems.
Materials and methods
Ozone water
The materials used to produce ozone water were: an
oxygen cylinder with reduction valves and mano© Australian Society of Orthodontists Inc. 2010
meters; an ozone generator (Ozone, mod. EAS 30 UV) with a production capacity of 0.5 g/h (0.25 per
cent, p/p, in the mixture of oxygen and ozone); a
crystal reactor with a capacity of 100 ml, coupled to
the ozone generator. To produce ozone water, a mixture of oxygen and ozone were bubbled through 100
ml of distilled water during autoclaving in the crystal
reactor. To ensure sterilisation and cleaning of the
system, ozone was bubbled through 100 ml of autoclaved distilled water, contained in the crystal reactor,
for 20 minutes. This water was discarded and
replaced with an equal volume of water to start the
experiment. The ozone concentration in the water
used was 0.6 mg/L.
Preparation of the teeth
One hundred and twenty extracted, bovine permanent mandibular incisors were collected and cleaned.
They were then placed in 10 per cent formaldehyde
Australian Orthodontic Journal Volume 26 No. 1 May 2010
73
PITHON AND SANTOS
Table I. Comparisons of shear bond strength, in megapascals.
Table II. ARI scores.
Group
Group
1
2
3
4
Mean
SD
Minimum
Median Maximum ANOVA
21.02
20.07
19.81
19.44
2.41
1.94
2.34
1.87
17.27
16.70
16.23
17.23
22.07
20.21
20.06
18.73
24.24
23.1
22.9
23.2
A
A
A
A
Group 1: Transbond XT/tap water; Group 2: Transbond XT/ozone
water; Group 3: Fuji Ortho LC/tap water; Group 4: Fuji Ortho
LC/ozone water
Groups with the same letter were not significantly different from each
other, p > 0.05
solution and stored in a refrigerator (8 °C) until
required. Only caries-free teeth with intact buccal
enamel, no previous chemical treatment (e.g. hydrogen peroxide) and no enamel cracks caused by the
extraction forceps were used.
The teeth were embedded in PVC reducing bushes
(Tigre, Joinville, Brazil) with acrylic resin (Clássico,
São Paulo, Brazil), leaving only the crowns exposed.
To faciliate mechanical testing, the buccal surfaces of
the crowns were placed perpendicular to the shearing
base of the dies. The embedded teeth were placed in
distilled water and stored in a refrigerator (8 °C) until
required for testing.
The mounted teeth were randomly divided into four
equal groups. The buccal surfaces of the teeth were
cleaned for 15 seconds with a paste made from extrafine pumice (S.S. White, Juiz de Fora, Brazil) mixed
with either tap water (Groups 1 and 3) or ozone water
(Groups 2 and 4) and rubber prophylaxis cups
(Viking, KG Sorensen, Barueri, Brazil). The teeth
were then rinsed with an air - tap water spray (Groups
1 and 3) or an ozone water spray (Groups 2 and 4) for
15 seconds and dried with oil-free air for 15 seconds.
The rubber cups were replaced after they had been
used on five teeth in the same group.
Stainless steel 0.018 inch upper central incisor
brackets (Morelli, Sorocaba, Brazil), with a mean base
area of 14.2 mm2, were bonded to the teeth in
Groups 1 and 2 with Transbond XT (3M Unitek,
Monrovia, CA, USA) and to the teeth in Groups 3
and 4 with Fuji Ortho LC (GC America
Corporation, Tokyo, Japan). The resin was applied to
each bracket base and the bracket seated on the tooth
with 300 g force using a Correx gauge for 10 seconds.
The force was applied uniformly to ensure an even
74
Australian Orthodontic Journal Volume 26 No. 1 May 2010
1
2
3
4
ARI score*
0
1
2
3
3
9
0
0
3
6
3
12
15
12
15
18
9
3
12
0
* 0, no adhesive remaining on the tooth; 1, less than half of adhesive
remaining on the tooth; 2, more than half of the adhesive remaining on
the tooth; 3, all adhesive remaining on the teeth
adhesive thickness between bracket and enamel, and
the adhesive flash was removed with a dental probe.
A Light Curing Unit 2500 (3M Dental Products,
Oakdale, CA, USA) with an intensity of 550
mW/cm2 was applied at a distance of 1 mm to
each side of the bracket for 10 seconds (Total curing
time: 40 seconds). The light intensity was calibrated
for each bracket using a radiometer (Demetron,
Danburry, CT, USA).
The bonded teeth were left undisturbed for 30
minutes to ensure complete polymerisation of the
adhesive. After a 24-hour period of immersion in
distilled water the specimens were alternately cycled
(500 cycles) through distilled water baths at 5 °C
and 55 °C, with a dwell time of 15 seconds in each
bath.6
Mechanical testing and statistical analyses
A purpose-built device was used to stabilise the specimens during mechanical testing. The brackets were
debonded with an Emic DL 10.000 universal testing
machine (São José dos Pinhais, Paraná, Brazil) at a
crosshead speed of 0.5 mm/minute. A shear load was
applied to the bracket base with a chisel-shaped rod
and the force required to dislodge the bracket recorded. The shear bond strength (SBS) in megapascals
(MPa) was calculated from this data. Following
debonding the enamel surfaces were examined with a
stereomicroscope (Stemi 2000-C; Carl Zeiss,
Göttingen, Germany) at x16 magnification and the
adhesive remnant index (ARI) recorded. With the latter index: 0, no adhesive left on the tooth; 1, less than
half the adhesive left on the tooth; 2, more than half
the adhesive left on the tooth; 3, all of the adhesive
left on the tooth.
DOES OZONE WATER AFFECT THE BOND STRENGTHS OF ORTHODONTIC BRACKETS
Table III. Group comparisons of the ARI, probability values.
1
1
2
3
4
2
3
4
26.00
0.128
0.508
0.030
0.155
0.511
0.024
24.00
Significant values in bold
Statistical analyses were performed using the
Statistical Package for the Social Sciences version 13.0
(SPSS Inc, Chicago, IL, USA). An analysis of variance (ANOVA) was used to determine whether there
were significant differences among the groups and the
Tukey HSD test was applied post-hoc if necessary.
The Kruskal-Wallis and Mann-Whitney U tests were
used to compare the ARI scores.
Shear bond strength (Mpa)
Groups
22.00
20.00
18.00
16.00
1
2
3
4
Groups
Figure 1. Box plots of shear bond strength values.
Results
The results are given in Tables I to III and Figure 1.
The SBS of the brackets washed with ozone water
(Groups 2 and 4) were slightly less than the brackets
washed with tap water (Groups 1 and 3), but the
differences were not statistically significant.
There were, however, statistically significant differences in the ARI between Groups 2 and 3 and
Groups 3 and 4 (Tables II and III).
Discussion
Contamination of piped water supplies with microorganisms poses a health danger to patients. Ozone,
which has an antimicrobial action, is used to prevent
the formation of biofilms in water pipes and to disinfect water distribution systems in dental offices.4,7–10
Although ozone water is widely used, little is known
of its effects on the polymerisation processes of
adhesive and restorative materials. We postulated that
the additional oxygen molecules in ozone water,
which contains three times more oxygen than tap
water, may hamper the polymerisation processes in
orthodontic adhesive materials and affect the shear
bond strengths and sites of fracture of the materials.11–21 We found no statistically significant differences in the shear bond strengths of resins when
ozone water was used to wash the enamel prior to
bonding, but the sites of resin fracture during
debonding were affected. Used in this limited way, we
concluded that ozone water did not affect the bond
strengths of brackets bonded with Transbond XT and
Fuji Ortho LC composite resins.
The materials we evaluated (Transbond XT and Fuji
Ortho LC) are widely used in the clinic and in shear
bond strength studies.22–25 Although we found no
statistically significant differences between the SBSs of
the materials, the mean SBS of the brackets bonded
with Transbond XT were slightly higher and more
variable than the brackets in comparable groups
bonded with Fuji Ortho LC resin. The mean shear
bond strengths we found agree with previous studies
that have used Transbond XT and Fuji Ortho LC,23,24
and fell within the range of values (5–20 Mpa)
considered by Owens26 to be suitable for clinical use.
Lower mean ARI values, indicating that less adhesive
remained on the teeth after debonding, were found in
the groups washed with ozone water (Groups 2 and 4)
than those washed with tap water (Groups 1 and 3).
These differences were significant between Groups 2
(Transbond XT/ozone water) and 3 (Fuji Ortho
LC/tap water) and between Groups 3 (Fuji Ortho
LC/tap water) and 4 (Fuji Ortho LC/ozone water).
These results are clinically important, since with a
slight reduction in ARI promoted by the ozone water,
the enamel surface is less protected during the
bracket removal process, and fractures of the enamel
are more likely to occur.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
75
PITHON AND SANTOS
We also found a reduction in the mean ARI between
the teeth bleached with different concentrations of
hydrogen peroxide, although there was no statistical
difference between the bond strengths.27 In the present study with ozone water, the differences in ARI
can be attributed to the presence of oxygen molecules
in the bond area. It is worth pointing out that the
concentration of ozone in the water we used was 0.6
mg/L, the same concentration was used by Velano,28
in her study of the micro-biocidal action of ozone
water. This concentration appears to be ideally suited
to disinfect dental water systems and prevent the formation of biofilms.
7.
8.
9.
10.
11.
12.
Conclusion
The hypothesis that ozone water would interfere in
the shear bond strength of orthodontic brackets was
not proved. Washing the enamel with ozone water
before orthodontic bracket bonding did not diminish
the shear bond strength, but it did alter the sites of
resin fracture when Fuji Ortho LC was used.
Corresponding author
Dr Matheus Melo Pithon
Av. Otávio Santos
395, sala 705
Centro Odontomédico
Dr. Altamirando da Costa Lima
Vitória da Conquista
Bahia
Brazil CEP 45020750
Email: matheuspithon@bol.com.br
13.
14.
15.
16.
17.
18.
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Edmunds LM, Rawlinson A. The effect of cleaning on blood
contamination in the dental surgery following periodontal
procedures. Aust Dent J 1998;43:349–53.
Huntington MK, Williams JF, Mackenzie CD. Endotoxin
contamination in the dental surgery. J Med Microbiol 2007;
56:1230–4.
Putnins EE, Di Giovanni D, Bhullar AS. Dental unit waterline contamination and its possible implications during
periodontal surgery. J Periodontol 2001;72:393–400.
Acosta–Gio AE, Borges–Yanez SA, Flores M, Herrera A,
Jeronimo J, Martinez M et al. Infection control attitudes
and perceptions among dental students in Latin America:
implications for dental education. Int Dent J 2008;58:
187–93.
Askarian M, Assadian O. Infection control practices among
dental professionals in Shiraz Dentistry School, Iran. Arch
Iran Med 2009;12:48–51.
Thomas MV, Jarboe G, Frazer RQ. Infection control in the
dental office. Dent Clin North Am 2008;52:609–628, x.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
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23.
Zimmerli M, Widmer AF, Dangel M, Filippi A, Frei R,
Meyer J. Methicillin–resistant Staphylococcus aureus
(MRSA) among dental patients: a problem for infection
control in dentistry? Clin Oral Investig 2008.
Loncar B, Stipetic MM, Matosevic D, Tarle Z. Ozone
application in dentistry. Arch Med Res 2009;40:136–7.
Nogales CG, Ferrari PH, Kantorovich EO, Lage–Marques
JL. Ozone therapy in medicine and dentistry. J Contemp
Dent Pract 2008;9:75–84.
Wilson SR, Solomon KR, Tang X. Changes in tropospheric
composition and air quality due to stratospheric ozone
depletion and climate change. Photochem Photobiol Sci
2007;6:301–10.
Nagayoshi M, Kitamura C, Fukuizumi T, Nishihara T,
Terashita M. Antimicrobial effect of ozonated water on
bacteria invading dentinal tubules. J Endod 2004;30:
778–81.
Pereira JT, Costa AO, de Oliveira Silva MB, Schuchard W,
Osaki SC, de Castro EA et al. Comparing the efficacy of
chlorine, chlorine dioxide, and ozone in the inactivation of
Cryptosporidium parvum in water from Parana State,
Southern Brazil. Appl Biochem Biotechnol 2008;151:
464–73.
Uhm HS, Hong YF, Lee HY, Park YH. Increase in the ozone
decay time in acidic ozone water and its effects on sterilization of biological warfare agents. J Hazard Mater 2009;168:
1595–601.
Zuma F, Lin J, Jonnalagadda SB. Ozone–initiated disinfection kinetics of Escherichia coli in water. J Environ Sci
Health A Tox Hazard Subst Environ Eng 2009;44:48–56.
Azarpazhooh A, Limeback H. The application of ozone in
dentistry: a systematic review of literature. J Dent 2008;36:
104–16.
King MD, Thompson KC, Ward AD, Pfrang C, Hughes BR.
Oxidation of biogenic and water–soluble compounds in
aqueous and organic aerosol droplets by ozone: a kinetic and
product analysis approach using laser Raman tweezers.
Faraday Discuss 2008;137:173–192; discussion 193–204.
Lazzarotto B, Frioud M, Larcheveque G, Mitev V, Quaglia P,
Simeonov V et al. Ozone and water–vapor measurements by
Raman lidar in the planetary boundary layer: error sources
and field measurements. Appl Opt 2001;40:2985–97.
Amra I, Samsodien G, Shaikh A, Lalloo R. Xeno III
self–etching adhesive in orthodontic bonding: the next
generation. Am J Orthod Dentofacial Orthop 2007;131:160
e111–115.
Årtun J, Bergland S. Clinical trials with crystal growth
conditioning as an alternative to acid–etch enamel
pretreatment. Am J Orthod 1984;85:333–40.
Coleman DC, O’Donnell MJ, Shore AC, Russell RJ. Biofilm
problems in dental unit water systems and its practical
control. J Appl Microbiol 2009;106:1424–37.
Johansson E, Andersson–Wenckert I, Hagenbjork–
Gustafsson A, Van Dijken JW. Ozone air levels adjacent to a
dental ozone gas delivery system. Acta Odontol Scand 2007;
65:324–30.
Cacciafesta V, Sfondrini MF, Stifanelli P, Scribante A, Klersy
C. The effect of bleaching on shear bond strength of
brackets bonded with a resin–modified glass ionomer. Am J
Orthod Dentofacial Orthop 2006;130:83–7.
Pithon MM, de Oliveira Ruellas AC, Sant’Anna EF, de
Oliveira MV, Alves Bernardes LA. Shear bond strength of
brackets bonded to enamel with a self–etching primer.
Effects of increasing storage time after activation. Angle
Orthod 2009;79:133–7.
DOES OZONE WATER AFFECT THE BOND STRENGTHS OF ORTHODONTIC BRACKETS
24. Pithon MM, Dos Santos RL, de Oliveira MV, Ruellas AC,
Romano FL. Metallic brackets bonded with resin–reinforced
glass ionomer cements under different enamel conditions.
Angle Orthod 2006;76:700–4.
25 Pithon MM, Oliveira MV, Ruellas AC, Bolognese AM,
Romano FL. Shear bond strength of orthodontic brackets to
enamel under different surface treatment conditions. J Appl
Oral Sci 2007;15:127–30.
26. Owens SE, Miller BH. A comparison of shear bond
strengths of three visible light–cured orthodontic adhesives.
Angle Orthod 2000;70:352–6.
27. Pithon MM, Ruellas AC, Sant’Anna EF. Effect of bleaching
with hydrogen peroxide into different concentrations on
shear strength of brackets bonded with a resin–modified
glass ionomer. Braz J Oral Sci 2008;7:1484–8.
28. Velano HE, do Nascimento LC, de Barros LM, Panzeri H. In
vitro assessment of antibacterial activity of ozonized water
against Staphylococcus aureus. Pesqui Odontol Bras
2001;15: 18–22.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
77
Incremental effects of facemask therapy associated
with intermaxillary mechanics
Guilherme Thiesen, * Juliana de Oliveira da Luz Fontes, † Michella Dinah Zastrow +
and Naudy Brodbeck May *
Departments of Orthodontics* and Radiology,+ School of Dentistry, University of South Santa Catarina and Private Practice,† Florianópolis,
Santa Catarina, Brazil
Objectives: To determine the dentofacial changes in children with skeletal Class III malocclusions treated with maxillary
expansion, external maxillary protraction and intermaxillary traction.
Methods: Fifteen Class III patients in either the deciduous or the mixed dentition (Mean age: 7.6 years; SD: 1.9 years) were
used. The children were treated with a modified Haas expander, a modified lingual arch, intermaxillary elastics and facemask
for nine months. Lateral cephalometric radiographs were taken at the beginning of treatment (T1) and at 3-month intervals (T2,
T3, T4).
Results: Most significant sagittal skeletal modifications occurred in the first three months of treatment. During the first three months
of treatment the upper and lower incisors tipped lingually and the face height increased. Towards the end of treatment the
upper incisors proclined and the upper lip became more protrusive.
Conclusion: The therapy corrected the horizontal skeletal and arch discrepancies and improved the positions of the lips.
(Aust Orthod J 2010; 26: 78–83)
Received for publication: October 2009
Accepted: February 2010
Guilherme Thiesen: guilhermethiesen@yahoo.com.br and guilherme.thiesen@unisul.br
Juliana de Oliveira da Luz Fontes: xaozinha@hotmail.com
Michella Dinah Zastrow: michelladz@yahoo.com.br
Naudy Brodbeck May: naudy@unisul.br
Introduction
Skeletal Class III malocclusion is considered one of
the most complex and difficult orthodontic problems
to treat. Much controversy and uncertainty surrounds
the efficacy and stability of early treatment of this
condition.1–3 Since 45 to 65 per cent of skeletal Class
III malocclusions have maxillary retrusion and a normal or prognathic mandible, many Class III patients
can be managed with maxillary expansion and facemask therapy.4,5 Although this approach has been
described as maxillary protraction, the anteroposterior discrepancy is corrected by a combination of
skeletal and dental movements in the maxilla and
mandible.2,6–13
Recent publications have reported that favourable
outcomes can be maintained long-term in approximately 65 to 75 per cent of cases treated with this
type of early orthopaedic Class III treatment.14–18
However, a recent finite element study by Holberg,
78
Australian Orthodontic Journal Volume 26 No. 1 May 2010
Mahaini and Rudzki19 has cast doubt on the notion
of remodelling changes in the facial skeleton. They
reported that the strains applied by a facemask were
not high enough to stimulate bone growth in the
circum-maxillary sutures. Their findings lead us to
formulate a study to investigate the skeletal, dentoalveolar and soft tissue effects of combined facemask,
intermaxillary traction and rapid maxillary expansion
therapy in young subjects with skeletal Class III malocclusion. We postulated that it would be possible to
maximise the skeletal changes and minimise the dentoalveolar changes by starting treatment in the late
deciduous to mixed dentition. We also aimed to
determine the changes at short intervals throughout
treatment.
Materials and methods
The sample comprised 15 children (8 girls, 7 boys)
between 5 years, 1 month and 11 years, 2 months of
© Australian Society of Orthodontists Inc. 2010
EFFECTS OF FACEMASK THERAPY
N
N
S
S
Po
Co
Or
ANB
Po
N
PNS
A
Go
U6c
L6c
U1t L1t
Go
Cm
U1a ANS
A
UI
U1t L1t
L1a
B
Pog
Gn
(a)
PNS
ANS
LI
B
Pog
Mo
(b)
Me
(c)
Figure 1. Measurements used.
(a) Sagittal change in maxilla: SNA, NPerp-A, Co-A
Sagittal change in mandible: SNB, NPerp-Pog, Co-Gn
Maxillo-mandibular relationship: ANB, Wits appraisal
(b) Vertical relationship: SN/Ocl, SN/PP, SN/GoMe, FMA, ANS-Me
(c) Maxillary teeth: 1/NA, 1-NA, 1/PP
Mandibular teeth: 1/NB, 1-NB, IMPA
Facial profile: Steiner ‘S’ line, S-Ul; Steiner ‘S’ line, S-Ll
age (Mean age: 7.6 ± 1.9 years) with Class III malocclusion. Consecutive subjects were selected
prospectively and treated for nine months. The selection criteria included: Class III malocclusion characterised by an anterior crossbite or edge-to-edge incisal
relationship and a Wits appraisal of -2 mm or less; a
maxillary deficiency established by facial analysis;20 a
stage of dental development between late deciduous
dentition and mixed dentition; no previous orthodontic or orthopaedic treatment; no other craniofacial anomalies. All subjects were treated before their
pubertal peak in mandibular growth, as verified by
the cervical vertebral maturation method.21 The
study was approved by the Ethics Committee of the
University of South Santa Catarina.
Cephalometric analysis
Lateral cephalometric radiographs were taken at the
start of treatment (T1) and at 3-month intervals (T2,
T3, T4). The radiographs were taken with the teeth
in centric relation, and the image magnification was
7 per cent. All radiographs were traced and measured
with digital calipers or protractor by the same operator (G.T.). The linear measurements were recorded to
the nearest 0.1 mm and the angular measurements to
the nearest 0.1 degree. The landmarks and measurements used in the study are shown in Figure 1.
Treatment regimen
The upper appliances were a modified Haas rapid
maxillary expansion appliance soldered to bands on
the deciduous second molars or first permanent
molars (Figure 2). When possible, the first premolars
were also banded. Teeth not banded were generally
bonded to the appliance with composite resin. Heavy
0.045 inch wires joined the palatal appliance and
bands and contacted the palatal and buccal surfaces
of the posterior teeth. Hooks for extra-oral and intermaxillary elastics were placed in the buccal wires. The
anterior hooks extended to the canine areas. An 11
mm expansion screw, placed in the midline of the
palatal appliance, was activated a quarter turn twice
daily (0.2 mm per turn) until fully activated. At the
end of the second week a protraction force of 450 to
600 g per side with a downward vector of 30 degrees
to the occlusal plane was used. The elastics were
attached to a Petit facemask (Orthotech, Porto
Alegre, Brazil) and the subjects were instructed to
wear the appliance for 12 hours a day.
In the lower ach, a modified 0.045 inch lingual arch
was soldered to bands on either the deciduous second
molars or, generally, the first permanent molars. The
buccal surfaces of teeth not banded were bonded to
the appliance with composite resin. Buccal 0.045
Australian Orthodontic Journal Volume 26 No. 1 May 2010
79
THIESEN ET AL
(a)
(b)
(c)
Figure 2. Appliances used in this study for Class III correction:
(a) modified Haas expander. (b) modified lingual arch. (c) Class III intermaxillary elastics and extra-oral elastics to the facemask.
inch wires were soldered to the lower molar bands
and formed into hooks for Class III intermaxillary
elastics. The hooks extended forwards to the canines.
The intermaxillary elastics delivered 200 to 350 g per
side and subjects were instructed to use the elastics 24
hours per day, only removing them during eating and
tooth brushing (Figure 2).
Statistical analysis
The data were normally distributed. The cephalometric measurements were compared at T1, T2, T3 and
T4 by the analysis of variance of repetitive measurements, since the same individual was analysed at different times. Tukey’s HSD test was then used to determine which time intervals were significantly different.
The significance level was set at p ≤ 0.05 for all tests.
All measurements were re-traced on two separate
occasions with a 2-week interval between them. The
systematic error was assessed using a paired t-test and
the combined method errors in location of the landmarks, tracing and measurement with Dahlberg’s formula. There was no systematic error and no error
exceeded 0.5 mm or 0.5 degree.
Results
Most of the maxillary sagittal changes occurred in the
first three months of treatment, as demonstrated by
the SNA angle, NPerp-A and Co-A (Table I). The
maxillary incisors (1/PP) retroclined in the first three
months then slowly proclined over the following six
months. The SNB angle and NPerp-Pog remained
unchanged throughout treatment.
Mandibular length (Co-Gn) increased significantly
from T1 to T4. The lower incisors (IMPA) were
80
Australian Orthodontic Journal Volume 26 No. 1 May 2010
tipped progressively lingually from T1 to T4, but
there were no significant changes in 1-NB and 1/NB.
The ANB angle and Wits appraisal showed significant changes in maxillo-mandibular relations
from T1 to T4. The greatest changes in these
measurements occurred in the first three months of
treatment.
There were no significant changes in either FMA or
SN/GoMe, indicating that the therapy did not
induce a growth rotation. There was no significant
change in the inclination of the palatal plane to the
cranial base (SN/PP), although the lower anterior
facial height (ANS-Me) and occlusal plane to cranial
base (SN/Ocl) increased throughout treatment (Table
I). Small, but statistically significant, changes
occurred in the positions of the lips (S-U1, S-L1),
indicating that the soft tissue profile became more
convex with treatment.
Discussion
Subjects with skeletal Class III malocclusion often
present with concave facial profiles, nasomaxillary
retrusion, and a prominent lower lip and lower third
of the face. The goal of early treatment is to produce
the greatest orthopaedic effect with minimal dental
compensation. Previous attempts to maximise the
orthopaedic effects of facemask therapy have used
fixed splints with elastics, skeletal anchorage with
miniplates and ankylosed deciduous canines.25–29
Our treatment protocol of combined maxillary
expansion, facemask therapy and Class III mechanics
straightened the skeletal and soft tissue facial profiles
of our young subjects with only a few, small
dentoalveolar changes, but it was no more successful
than some of the appliance combinations others have
EFFECTS OF FACEMASK THERAPY
Table I. Combined facemask therapy, comparisons at 3-month intervals.
Stages
Measurement
T1
Mean (SD)
T2
Mean (SD)
SNA (degrees)
78.12 (2.77) a,b,c 80.36 (3.12) a
NPerp-A (mm)
-0.53 (2.69) a,b,c
2.31 (2.14) a
Co-A (mm)
82.98 (3.21) a,b,c 85.55 (3.09) a,d
SNB (degrees)
80.56 (3.11)
79.17 (3.23)
NPerp-Pog (mm)
-0.11 (4.72)
-0.53 (5.01)
Co-Gn (mm)
110.77 (5.91) a
111.35 (6.31)
ANB (degrees)
-2.44 (2.81) a,b,c
1.19 (2.56) a
Wits (mm)
-5.70 (3.17) a,b,c
-0.05 (4.21) a
1/NA (degrees)
24.87 (3.13)
23.97 (2.98)
1-NA (mm)
4.61 (2.77)
4.21 (2.48)
1/PP (degrees)
114.98 (6.32) a
112.43 (6.99) a,b
1/NB (degrees)
23.55 (5.78)
22.53 (4.44)
1-NB (mm)
3.21 (2.01)
3.02 (2.12)
IMPA (degrees)
88.89 (6.13) a,b,c 86.03 (6.21) a
SN/Ocl (degrees)
19.36 (6.74)
19.76 (6.87) a
SN/PP (degrees)
8.31 (3.23)
7.67 (3.10)
SN/GoMe (degrees) 37.88 (4.64)
40.01 (4.89)
FMA (degrees)
26.21 (5.14)
27.63 (5.97)
ANS-Me (mm)
61.11 (5.60) a,b,c 64.60 (5.35) a,d
S-Ul (mm)
-0.45 (2.98) a,b
0.25 (3.10) c
S-Ll (mm)
1.88 (3.92) a
0.32 (3.43)
T3
Mean (SD)
80.43 (2.63)
2.32 (2.41)
86.07 (3.06)
79.31 (2.81)
-0.16 (4.70)
111.99 (7.40)
1.12 (2.71)
0.18 (4.03)
24.55 (2.87)
4.35 (2.91)
113.37 (6.64)
21.54 (6.01)
3.01 (2.14)
85.83 (6.35)
16.02 (7.31)
7.76 (3.05)
38.87 (5.05)
26.43 (4.66)
65.17 (4.98)
0.96 (3.17)
0.45 (3.41)
T4
Mean (SD)
b
b
b
b
b
b
a
b
a,d
80.44
2.49
86.94
79.14
0.02
112.75
1.30
0.25
25.03
5.08
116.53
21.30
2.96
85.12
17.51
8.31
38.96
25.84
65.89
1.98
0.68
(3.11)
(2.29)
(3.09)
(3.74)
(4.79)
(8.17)
(3.29)
(3.07)
(3.32)
(2.49)
(7.01)
(6.20)
(2.32)
(6.01)
(8.39)
(3.28)
(5.53)
(5.26)
(5.19)
(2.73)
(3.61)
p*
c
c
c,d
a
c
c
b
c
c,d
b,c,d
a
0.0001
<0.0001
<0.0001
0. 077
0.098
0.006
<0.0001
<0.0001
0.061
0.059
0.003
0.099
0.171
0.001
0.029
0.606
0.082
0.075
<0.0001
0.0003
0.040
Means followed by the same letter are statistically different
*ANOVA, significant values in bold.
In the first three months of treatment the upper
incisors tipped palatally and then tipped labially over
the next six months. We attribute the initial palatal
movement of the upper incisors (1/PP) to the maxillary expansion, which increased the perimeter of the
upper arch, and labial tipping of the upper incisors to
the combined effects of Class III traction and facemask therapy.34,35 The lower incisors (IMPA) tipped
lingually throughout treatment, but the changes,
although statistically significant, were less than 4
degrees. Pressure from the mandibular pad on the
facemask may be responsible for these changes.
changes with a view to identifying the effects of the
various components of our therapy. As mentioned
above, maxillary expansion and unwanted pressure
from the facemask were probably responsible for the
incisors tipping lingually in our young subjects.
Significant sagittal skeletal modifications occurred in
the first three months of treatment (SNA, NPerp-A,
Co-A), although lingual tipping of the lower incisors
could account for some of these changes. After the
initial period, the changes in all three measurements
were maintained until the end of the treatment. A statistically significant increase in the vertical dimension
(ANS-Me) also occurred during treatment, but some
of this increase (Mean difference: 4.58 mm) may be
due to the mechanics and some to facial growth. The
vertical change was small and may not be of clinical
significance.
We decided to follow our subjects at 3-month intervals because we wanted to determine the incremental
In this preliminary study, our protocol of maxillary
expansion, facemask therapy and intermaxillary
used.2,3,7,8,10,12,13,27,29–33 It has been reported that
combined facemask therapy and Class III mechanics
are no more effective in treating skeletal Class III
malocclusions than facemask therapy alone.1,2,29,33
Australian Orthodontic Journal Volume 26 No. 1 May 2010
81
THIESEN ET AL
mechanics resulted in the skeletal changes and progressive dental compensations we were aiming for.
Although most of the changes occurred in the first
three months of treatment, sustained treatment is
essential to correct the overjet and molar relationships
and maintain the skeletal correction. Ideally, Class III
malocclusions in young subjects should be overcorrected and retained as facial growth can undo any
favourable changes.14,16,18 Further studies are
required to determine the amount of overcorrection
required, the length of retention, the effects of normal facial growth and the contributions made by the
various appliances. Moreover, the limitations in the
present study, such as the small sample size and the
lack of untreated control group should be mentioned.
6.
7.
8.
9.
10.
11.
12.
Conclusions
Correction of a skeletal Class III malocclusion in
young subjects with combined facemask therapy,
maxillary expansion and intermaxillary mechanics
resulted from forward movement of the maxilla and
incisor tipping. The most significant skeletal modifications occurred in the first three months of treatment. The therapy improved the positions of the lips
and resulted in a more convex profile.
13.
14.
15.
16.
Corresponding author
Professor Guilherme Thiesen
Av. Madre Benvenuta
1285 - Santa Mônica
CEP: 88035-001
Florianópolis – SC
Brazil
Email: guilhermethiesen@yahoo.com.br
and guilherme.thiesen@unisul.br
References
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2.
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4.
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Ngan P, Wei SH, Hägg U, Yiu C, Merwin D, Stickel B.
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combined palatal expansion and facemask therapy on Class
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da Silva Filho OG, Magro AC, Capelozza Filho L. Early
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Am J Orthod Dentofacial Orthop 2004;126:16–22.
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EFFECTS OF FACEMASK THERAPY
25. Ferro A, Nucci LP, Ferro F, Gallo C. Long-term stability of
skeletal Class III patients treated with splints, Class III elastics, and chincup. Am J Orthod Dentofacial Orthop 2003;
123:423–34.
26. Hong H, Ngan P, Han G, Qi LG, Wei SH. Use of onplants
as stable anchorage for facemask treatment: a case report.
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27. Kircelli BH, Pektas ZÖ, Uçkan S. Orthopedic protraction
with skeletal anchorage in a patient with maxillary hypoplasia and hypodontia. Angle Orthod 2006;76:156–63.
28. Liou EJ, Tsai WC. A new protocol for maxillary protraction
in cleft patients: repetitive weekly protocol of alternate rapid
maxillary expansions and constrictions. Cleft Palate
Craniofac J 2005;42:121–7.
29. da Silva Filho OG, Osawa TO, Okada CH, Okada HY,
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31. Pangrazio-Kulbersh V, Berger J, Kersten G. Effects of protraction mechanics on the midface. Am J Orthod
Dentofacial Orthop 1998;114:484–91.
32. Saadia M, Torres E. Sagital changes after maxillary protraction with expansion in Class III patients in the primary,
mixed and late mixed dentitions: a longitudinal retrospective study. Am J Orthod Dentofacial Orthop 2000;117:
669–80.
33. Macdonald KE, Kapust AJ, Turley PK. Cephalometric
changes after the correction of Class III malocclusion with
maxillary expansion facemask therapy. Am J Orthod
Dentofacial Orthop 1999;116:13–24.
34. Chung C, Font B. Skeletal and dental changes in the sagittal, vertical, and transverse dimensions after rapid palatal
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569–75.
35. Wertz RA. Skeletal and dental changes accompanying rapid
midpalatal suture opening. Am J Orthod 1970;58:41–66.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
83
Bond strengths of different orthodontic adhesives
after enamel conditioning with the same
self-etching primer
Rogelio J. Scougall-Vilchis, * Chrisel Zárate-Díaz, † Shusuke Kusakabe + and Kohji
Yamamoto +
Department of Orthodontics, School of Dentistry, Autonomous University State of Mexico,* Private Practice, Toluca City, Mexico† and the
Division of Oral Functional Sciences and Rehabilitation, School of Dentistry, Asahi University, Japan+
Aim: To determine the shear bond strengths (SBS) of stainless steel brackets bonded with seven light-cured orthodontic adhesives
after the enamel was conditioned with the same self-etching primer.
Methods: A total of 140 extracted human molars were randomly divided into seven groups (N = 20). In all the groups, the
enamel was conditioned with Transbond Plus SEP (TPSEP). Stainless steel brackets were bonded with the following orthodontic
adhesives: Group I, Transbond XT; Group II, Blūgloo; Group III, BeautyOrtho Bond; Group IV, Enlight; Group V, Light Bond;
Group VI, Transbond CC; Group VII, Xeno Ortho. The teeth were stored in distilled water at 37 °C for 24 hours and
debonded with a universal testing machine. The modified adhesive remnant index (ARI) was also recorded.
Results: There were no significant differences in the SBS values among the groups: I (18.0 ± 7.4 MPa); II (18.3 ± 5.1 MPa);
III (14.8 ± 4.3 MPa); IV (18.3 ± 7.0 MPa); V (16.4 ± 4.3 MPa); VI (20.3 ± 5.3 MPa); VII (15.9 ± 6.4 MPa), but significant
differences in ARI were found.
Conclusions: The seven orthodontic adhesives evaluated in this study can be successfully used for bonding stainless steel
brackets when the enamel is conditioned with TPSEP, however, the differences among some groups might influence the clinical
bond strengths. In addition, the amount of residual adhesive remaining on the teeth after debonding differed among the
adhesives. Further studies are required to better understand the differences in SBS and ARI.
(Aust Orthod J 2010; 26: 84–89)
Received for publication: December 2008
Accepted: February 2010
Rogelio J. Scougall-Vilchis: rogelio_scougall@hotmail.com
Chrisel Zárate-Díaz: chzd@yahoo.com
Shusuke Kusakabe: kusakabe@dent.asahi-u.ac.jp
Kohji Yamamoto: yamamoto.k@ray.ocn.ne.jp
Introduction
For more than 40 years researchers have been working to improve the bonding of orthodontic brackets
to teeth. Recent developments have been the introduction of self-etching primers (SEP), originally
intended for use in operative dentistry, to successfully bond orthodontic brackets.1–3 These primers
cause less aggressive decalcification and less enamel
loss than traditional phosphoric acid etchants, are less
affected by humidity, prevent contamination with
saliva and are quick to apply.3,4 It has also been
reported that although these primers result in
short enamel tags, brackets bonded after enamel
84
Australian Orthodontic Journal Volume 26 No. 1 May 2010
conditioning with SEPs have adequate shear bond
strengths and, in many instances, less adhesive
remains on the teeth after debonding.5 As a rule they
are combined with a light-cured adhesive which
enables brackets to be ‘tacked’ immediately in
position.6
To our knowledge, Transbond Plus SEP (TPSEP) is
the only SEP that does not significantly affect the
shear bond strength (SBS) of orthodontic brackets.5
In light of the great diversity in ultrastructure, filler
content, microhardness and chemical composition of
different orthodontic adhesives,7 and the possibility
that TPSEP may not behave favourably with all
© Australian Society of Orthodontists Inc. 2010
BOND STRENGTHS OF DIFFERENT ADHESIVES WITH THE SAME SEP
Table I. Orthodontic adhesives used in this study.
Table II. Comparisons of the shear bond strengths of the adhesives.
Group Orthodontic
adhesive
Manufacturer
Group
I
II
III
IV
V
Transbond XT
Blūgloo
BeautyOrtho Bond
Enlight
Light Bond
VI
VII
Transbond CC
Xeno Ortho
3M Unitek, Monrovia, CA, USA
Ormco Corp., Glendora, CA, USA
Shofu Inc., Kyoto, Japan
Ormco Corp., Glendora, CA, USA
Reliance Orthodontic Products,
Itasca, IL, USA
3M Unitek, Monrovia, CA, USA
Dentsply-Sankin K.K., Tochigi,
Japan
adhesives, we decided to determine the bond
strengths of seven readily available light-cured orthodontic adhesives on the SBS of stainless steel brackets
after the enamel was conditioned with TPSEP.
Materials and methods
One hundred and forty extracted human molars were
collected and stored in a solution of 0.2 per cent
(wt/vol) thymol to prevent bacterial growth, until
required. The criteria for tooth selection included:
molars with intact enamel surfaces, no white spot
lesions and no history of orthodontic treatment or
chemical treatment for bleaching.8 The teeth were
rinsed with water and cleaned with a fluoride-free
paste (Pressage, Shofu Incorporated, Kyoto, Japan)
and rubber prophylactic cups (Merssage, Shofu
Incorporated, Kyoto, Japan) in a slow-speed handpiece. The teeth were then washed with water for 30
seconds and air-dried.
One hundred and forty stainless steel 0.018 inch,
standard edgewise, upper incisor brackets (Tomy
International, Tokyo, Japan) were used. The average
surface area of the bases of 10 randomly selected
brackets was 13.58 mm2.
The teeth were randomly divided into seven groups
(N = 20 per group). The buccal surface of each tooth
was conditioned with TPSEP (3M Unitek,
Monrovia, CA, USA) following the manufacturer’s
instructions.5 The TPSEP was rubbed on the enamel
surface for 5 seconds then gently dried with
compressed air for a few seconds.
The brackets were bonded with different light-cure
orthodontic adhesives (Table I). Immediately after
the brackets were placed, they were light-cured
I
II
III
IV
V
VI
VII
N Mean (MPa) SD
Transbond XT
Blūgloo
BeautyOrtho Bond
Enlight
Light Bond
Transbond CC
Xeno Ortho
20
20
20
20
20
20
20
18.0
18.3
14.8
18.3
16.4
20.3
15.9
Range
7.4
8.3 - 34.9
5.1 11.3 - 30.5
4.3
7.8 - 21.0
7.0
7.6 - 30.5
4.3
5.4 - 31.0
5.3
9.0 - 26.7
6.4
5.8 - 27.1
ANOVA, p > 0.05
(BlueLex, Yoshida Dental, Tokyo, Japan) for a total
of 20 seconds (10 seconds on the mesial edge of
the bracket and 10 seconds on the distal edge). All
procedures were performed by the same researcher.
SBS test
After bonding, a short length of 0.017 x 0.025 inch
stainless steel wire was ligated into each bracket slot
to reduce deformation of the bracket during debonding. The teeth were embedded in acrylic resin and
mounted in the universal testing machine (EZ
Graph, Shimazdu, Kyoto, Japan) with the labial
surfaces parallel to the debonding force.
An occluso-gingival load was applied to each bracket,
producing a shear force at the bracket – tooth interface. This was accomplished with the flattened end of
a steel rod attached to the crosshead of the universal
testing machine. The SBS was measured at a
crosshead speed of 0.5 mm/min and the load applied
at fracture was recorded in newtons (N) and converted to megapascals (MPa) by dividing the load by the
mean area of the bracket bases (13.58 mm2).
Following debonding, the teeth were stored in
distilled water at 37 °C for 24 hours.9
Modified adhesive remnant index
The enamel surface of each molar was inspected at
x10 magnification and the amount of residual adhesive remaining on the surface of the tooth scored with
the modified ARI: 1, all composite remained on the
tooth; 2, more than 90 per cent of the composite
remained on the tooth; 3, between 10 and 90 per cent
of the composite remained on the tooth; 4, less than
10 per cent of the composite remained on the tooth;
5, no composite remained on the tooth.10
Australian Orthodontic Journal Volume 26 No. 1 May 2010
85
SCOUGALL-VILCHIS ET AL
Table III. Distributions and percentages of adhesive remaining on the teeth after debonding.
Group
N
I Transbond XT
II Blūgloo
III BeautyOrtho Bond
IV Enlight
V Light Bond
VI Transbond CC
VII Xeno Ortho
20
20
20
20
20
20
20
1
0
0
2
0
0
0
8
(0)
(0)
(10)
(0)
(0)
(0)
(40)
2
0
3
9
2
2
4
7
Modified ARI scores
Count (Per cent)
3
(0)
(15)
(45)
(10)
(10)
(20)
(35)
10
9
9
8
8
11
5
(50)
(45)
(45)
(40)
(40)
(55)
(25)
5
6
0
7
8
5
0
4
(25)
(30)
(0)
(35)
(40)
(25)
(0)
5
5
2
0
3
2
0
0
(25)
(10)
(0)
(15)
(10)
(0)
(0)
χ2 = 81.82; df = 24, p = 0.0001
Statistical analysis
The SBS data were compared with a one-way
ANOVA and post-hoc Scheffe tests. The significance
in both tests was predetermined at p < 0.05. The
distributions of ARI scores were compared with a
chi-squared test.
Results
The SBS values and the descriptive statistics are presented in Table II. The mean SBS in all the groups
exceeded 14.8 MPa and there were no statistically
significant differences between the groups (ANOVA:
p > 0.05). Groups I (Mean: 18.0 ± 7.4 MPa), II
(Mean: 18.3 ± 5.1 MPa), and IV (Mean:18.3 ± 7.0
MPa) had comparable mean values of SBS followed
by Groups V (Mean: 16.4 ± 4.3 MPa) and VII
(Mean: 15.9 ± 6.4 MPa). Group VI (Mean: 20.3 ±
5.3 MPa) had the highest mean value and Group III
(Mean: 14.8 ± 4.3 MPa) the lowest mean SBS.
The ARI scores are given in Table III. The distributions of adhesive remnants in the groups were significantly different (p = 0.0001). The smallest amounts
of adhesive remnant were found in Group I with a
mean ARI score of 3. This group also had the highest
number of teeth with a score of 5 and no teeth with
scores of 1 or 2. Groups II, IV, V and VI showed
comparable ARI scores, with mean scores of 3. More
than 90 per cent of the composite remained on the
buccal surfaces (ARI: 2) of between 10 and 15 per
cent of the teeth in these groups, but no tooth had an
ARI score of 1. The teeth in Group VII followed by
Group III had the highest amount of adhesive left on
the tooth after debonding: 40 per cent and 10 per
86
Australian Orthodontic Journal Volume 26 No. 1 May 2010
cent, respectively. In these groups there were no teeth
with scores of 4 or 5.
Discussion
The SBS values for all TPSEP – composite combinations exceeded the range of values (6–8 MPa) considered by some researchers to be a suitable SBS for
routine clinical use.11,12 Stainless steel brackets can be
successfully bonded with any of the seven adhesives
we investigated after the enamel is conditioned
with TPSEP. However, we found different patterns
of adhesive fracture during debonding that may
influence the choice of adhesive.
In orthodontic practice, a reliable bond between the
brackets and enamel is essential,13 but as the appliances are temporary, methods that avoid damage to
the enamel during bonding and following debonding
are desirable.14,15 Self-etching primers for enamel
conditioning avoid the decalcification characteristic
of phosphoric acid-based agents.16 They provide a
‘gentler’ etch pattern, which has been illustrated in
several SEM studies.4,8,17 We selected TPSEP for
enamel conditioning because it is frequently used in
orthodontics,18 and brackets bonded to teeth conditioned with TPSEP had significantly higher SBSs
than those bonded after the application of other
SEPs.5,19 When different SEPs were used with the
same composite resin we found TPSEP – resin was
the only combination that did not affect the bond
strength significantly compared to the control
group etched with 37 per cent phosphoric acid for
15 seconds.19 When TPSEP was applied for only 3
seconds and the brackets debonded after 24 hours,
BOND STRENGTHS OF DIFFERENT ADHESIVES WITH THE SAME SEP
the orthodontic brackets presented higher SBS values
than those in which the enamel had been etched with
37 per cent phosphoric acid.9 Furthermore, TPSEP
has also been shown to provide higher 6-month survival rates than brackets bonded after a conventional
acid etch.20 Moreover, it has been shown to provide a
suitable bond strength even if it is contaminated with
saliva.21 A recent study reported that activated
TPSEP stored for up to 15 days did not significantly
affect the SBS of orthodontic brackets.18
The direct bonding of molar tubes is now a common
procedure in orthodontic practice. In spite of the fact
that the buccal surfaces of human molars have complex and variable shapes, the seven adhesives we evaluated yielded higher SBSs than considered adequate
to accomplish treatment.11,12 Although we found
there were no significant differences between the
TPSEP – adhesive combinations, thermal stresses can
significantly reduce the bond strength of TPSEP and
a longer study may have disclosed differences between
the groups.22 The SBS was variable in Groups I, IV,
and VII: findings that are consistent with a previous
study in which the enamel was conditioned with
TPSEP and the brackets were bonded with
Transbond XT.5 Groups I (Transbond XT), II
(Blūgloo), and IV (Enlight) had approximately the
same mean SBS values. A larger mean difference
(slightly >5 MPa) was found between Groups VI
(Transbond CC: 20.3 MPa) and III (BeautyOrtho
Bond: 14.8 MPa). An interesting finding was the
higher SBS value in Group VI (Transbond CC) when
compared with Group I (Transbond XT). As
Transbond CC is a fluoride-releasing adhesive, we
expected a lower SBS value than that obtained with
Transbond XT, but there was no significant difference
between the two resins. The concentration of fluoride
in Transbond CC did not appear to influence the
bond strength of the resin under the conditions in
our study.
As ceramic brackets have higher bond strengths than
stainless steel brackets, an adhesive with a low SBS,
such as BeautyOrtho Bond or Xeno Ortho, may be
preferable to adhesives with high bond strengths.20,23
The bond strengths of stainless steel and ceramic
brackets can be raised by treating the bracket pad
with a silicone product and altered by using a different etchant or by applying a caries-protective resin
after etching.25–27 Light Bond demonstrated slightly
higher SBS than Transbond XT when the enamel was
etched with phosphoric acid,26 and Blūgloo presented lower shear peel bond strength than Transbond XT.27 Light Bond had a significantly higher
SBS than both Transbond XT and Blūgloo after a
caries protective sealant was applied.27 With the combinations of TPSEP and resins we used, procedures
that increase the SBS appear to be unnecessary as the
bond strength values exceeded those considered to be
appropriate for most clinical procedures, but there
may be some advantages if the site of failure occurs at
the resin – enamel interface.
Although frequently used, the ARI is a problematic
parameter and the results should be regarded
cautiously. It has been demonstrated that the amount
of adhesive remaining on the tooth tends to be larger
when a high SBS value is obtained.5,28 However, our
findings are slightly contradictory as significantly
more adhesive was found in the groups with low SBS
values (Groups VII and III). In these groups, bracket
failure frequently occurred at the bracket – adhesive
interface. Pretreatment that enhances the visibility of
the resin flash or the bond strength at the resin –
bracket interface might reduce the amount of
adhesive left on the tooth after debonding and/or the
amount of time spent removing resin remnants.24 A
colouring agent in the resin flash has been tried.29
With improvements in the physical and mechanical
properties of composite resins, removing the adhesive
remnants after debonding has become a clinical
problem. Resin remnants may discolour over time
and retain plaque.30 Tooth cleaning is easier and faster
and iatrogenic damage during cleaning is less likely to
occur when brackets fail at the enamel – resin interface.5,10,31 However, bond failure at the bracket –
adhesive interface or within the adhesive is considered
to be safer than failure at the enamel – adhesive interface because enamel fracture can occur if failure
occurs at the latter site.10
Apart from enamel fracture or gouges from injudicious use of hand instruments or burs, the enamel lost
during orthodontic procedures is insignificant in
terms of the total thickness of the enamel.32
Nevertheless, enamel loss at the time of bracket
removal depends largely on the orthodontic materials
used, the method of debonding, the tactile ability of
the clinician and the instruments used.20,32 Least
enamel loss occurs when TPSEP is used and the
enamel cleaned with a slow-speed tungsten carbide
bur.28
Australian Orthodontic Journal Volume 26 No. 1 May 2010
87
SCOUGALL-VILCHIS ET AL
Conclusions
Under the conditions of this in-vitro study, the
following conclusions were drawn:
1. The seven orthodontic adhesives and TPSEP had
SBS values that exceeded the range of values (6–8
MPa) considered by some researchers to be suitable
for routine clinical use.
2. Stainless steel brackets can be successfully bonded
with any of these adhesive pastes when the enamel is
conditioned with TPSEP.
3. Less adhesive was found on the teeth when
Transbond XT, Blūgloo, Enlight, Light Bond and
Transbond CC were used.
4. Further in vivo and in-vitro studies are necessary to
determine the effects of time on the shear bonding
strengths and sites of fracture of the resin – TPSEP
combinations we studied.
7.
8.
9.
10.
11.
12.
13.
Corresponding author
Professor Rogelio J. Scougall-Vilchis
Department of Orthodontics
School of Dentistry
Autonomous University State of Mexico
Francisco Carbajal Bahena #241
Col. Morelos, Z.C. 50120
Toluca City
México
Tel: (+52) 722-280-91-13
Email: rogelio_scougall@hotmail.com
14.
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on enamel. Angle Orthod 2006;76:132–6.
Pithon MM, de Oliveira Ruellas AC, Sant’Anna EF, de
Oliveira MV, Alves Bernardes LA. Shear bond strength of
brackets bonded to enamel with a self-etching primer:
effects of increasing storage time after activation. Angle
Orthod 2009;79:133–7.
Scougall-Vilchis RJ, Ohashi S, Yamamoto K. Effects of selfetching primers on shear bond strength of orthodontic
brackets. Am J Orthod Dentofacial Orthop 2009;135:
424.e1–.e7.
dos Santos JE, Quioca J, Loguercio AD, Reis A. Six-month
bracket survival with a self-etch adhesive. Angle Orthod
2006;76:863–8.
Dunn WJ. Shear bond strength of an amorphous calciumphosphate–containing orthodontic resin cement. Am J
Orthod Dentofacial Orthop 2007;131:243–7.
Elekdag-Turk S, Turk T, Isci D, Ozkalayci N. Thermocycling
effects on shear bond strength of a self-etching primer.
Angle Orthod 2008;78:351–6.
Uysal T, Ulker M, Ramoglu SI, Ertas H. Microleakage under
metallic and ceramic brackets bonded with orthodontic selfetching primer systems. Angle Orthod 2008;78:1089–94.
Atsü SS, Gelgör IE, Sahin V. Effects of silica coating and
silane surface conditioning on the bond strength of metal
BOND STRENGTHS OF DIFFERENT ADHESIVES WITH THE SAME SEP
25.
26.
27.
28.
29.
and ceramic brackets to enamel. Angle Orthod 2006;76:
857–62.
Yamamoto A, Yoshida T, Tsubota K, Takamizawa T,
Kurokawa H, Miyazaki M. Orthodontic bracket bonding:
enamel bond strength vs time. Am J Orthod Dentofacial
Orthop 2006;130:435.e1–6.
Vicente A, Bravo LA, Romero M, Ortíz AJ, Canteras M.
Effects of 3 adhesion promoters on the shear bond strength
of orthodontic brackets: an in-vitro study. Am J Orthod
Dentofacial Orthop 2006;129:390–5.
Lowder PD, Foley T, Banting DW. Bond strength of 4
orthodontic adhesives used with a caries-protective resin
sealant. Am J Orthod Dentofacial Orthop 2008;134:291–5.
Hosein I, Sherriff M, Ireland AJ. Enamel loss during bonding, debonding, and cleanup with use of a self-etching
primer. Am J Orthod Dentofacial Orthop 2004;126:
717–24.
Armstrong D, Shen G, Petocz P, Darendeliler MA. Excess
adhesive flash upon bracket placement: a typodont study
comparing APC plus and transbond XT. Angle Orthod
2007;77:1101–8.
30. Kim SS, Park WK, Son WS, Ahn HS, Ro JH, Kim YD.
Enamel surface evaluation after removal of orthodontic
composite remnants by intraoral sandblasting: a 3-dimensional surface profilometry study. Am J Orthod Dentofacial
Orthop 2007;132:71–6.
31. Al Shamsi A, Cunningham JL, Lamey PJ, Lynch E. Shear
bond strength and residual adhesive after orthodontic bracket debonding. Angle Orthod 2006;76:694–9.
32. Al Shamsi AH, Cunningham JL, Lamey PJ, Lynch E. Threedimensional measurement of residual adhesive and enamel
loss on teeth after debonding of orthodontic brackets: an invitro study. Am J Orthod Dentofacial Orthop 2007;131:
301.e9–15.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
89
Multidisciplinary treatment of a fractured root:
a case report
Osmar Aparecido Cuoghi, * Álvaro Francisco Bosco, † Marcos Rogério de Mendonça, *
Pedro Marcelo Tondelli * and Yésselin Margot Miranda-Zamalloa *
Departments of Pediatric and Community Dentistry* and Surgery and Integrated Clinic,† Dental School of Araçatuba, São Paulo State
University, Araçatuba, Brazil.
Aim: To describe the orthodontic, periodontal and prosthetic management of a case with a 3 mm root fracture below the crest
of the alveolar bone.
Methods: The root was extruded and periodontal surgery carried out to improve aesthetics and dental function.
Conclusion: A multidisciplinary approach to the management of dental root fractures is necessary for successful treatment.
(Aust Orthod J 2010; 26: 90–94)
Received for publication: October 2009
Accepted: January 2010
Osmar Aparecido Cuoghi: osmarorto@terra.com.br
Álvaro Francisco Bosco: afbosco@foa.unesp.br
Marcos Rogério de Mendonça: marcosrm@foa.unesp.br
Pedro Marcelo Tondelli: tondelli.ortodontia@hotmail.com
Yésselin Margot Miranda-Zamalloa: yesselinmiranda@hotmail.com
Introduction
Successful management of a tooth with the root fractured below the crest of the alveolar bone requires the
cooperation of professionals with different knowledge
and skills. The options for treatment include: removal
of the fractured root and placement of either a
restoration, implant or prosthesis;1–5 periodontal
reconstruction, ranging from a simple gingivectomy
to surgical exposure of the fracture line;2,6–8 orthodontic extrusion with or without periodontal
surgery.2,6–8 The principal aim of orthodontic extrusion is to restore the relationship between the root
fragment, the crest of the alveolar bone and the gingival tissues.9,10 The final choice of therapy depends
on the level and angle of the fracture line and the
length of the apical root fragment.11
When the fracture occurs in the middle third of the
root, the prognosis is unfavourable because the
extruded and restored root fragment is unable to
resist normal functional loads.12 On the other hand,
if the fracture level is more-or-less horizontal and
close to the alveolar crest and providing the tooth has
not been displaced, periodontal surgery is usually the
90
Australian Orthodontic Journal Volume 26 No. 1 May 2010
most appropriate form of treatment. If, however, the
fracture line is more apically placed and periodontal
treatment will lead to loss of alveolar bone and an
unsightly appearance,9,13 a practicable option is to
extrude the apical root fragment. New bone is
deposited behind the extruded root fragment and the
root fragment – alveolar bone – gingival tissue relationships are restored.12–14 Often periodontal surgery
is required after extrusion to recontour the gingival
tissues.9,13
The aim of this report is to describe the multidisciplinary management of a fractured upper lateral
incisor requiring extrusion, periodontal surgery and
restoration.
Case report
A 30 year-old male was referred to the postgraduate
clinic at the Dental School, Araçatuba, São Paulo
State University, following a blow to the upper
left lateral incisor. The patient complained of pain
and the tooth, which had been restored with a porcelain post-crown, was very mobile. The gingivae
were inflamed and there appeared to be a fistula
© Australian Society of Orthodontists Inc. 2010
MULTIDISCIPLINARY TREATMENT OF A FRACTURED ROOT
Figure 2. The root fragment, ‘J’ hook and temporary wire bar after six weeks
extrusion. The temporary crown has been removed.
Figure 1. The fractured tooth, showing the fracture 3 mm below the alveolar
crest and the displaced crown.
about 3-4 mm above the labial gingival margin. An
intra-oral radiograph confirmed that the root and
alveolar bone had been fractured about 3 mm below
the alveolar crest and the coronal fragment displaced
mesio-occlusally (Figure 1).
The treatment objectives were to remove the coronal
fragment, extrude the apical fragment until the fracture level was about 3 mm beyond the alveolar crest,
fabricate a new post-crown and, if necessary, carry
out a gingivoplasty to recontour the gingival tissues.
We estimated approximately 6 mm of extrusion
was required for the fracture line to reach the desired
position.
The coronal fragment was removed under local
anaesthesia, and a short length of 0.7 mm stainless
steel wire with a small ‘J’ hook in the coronal end was
cemented in the root canal with composite resin. A
second length of 0.7 mm stainless steel wire with a
palatal loop and an acrylic crown was bonded with
composite resin (Concise, Unitek 3M, Monrovia,
CA, USA) to the adjacent teeth. This temporary
replacement maintained space for the future crown
and served as anchorage to extrude the apical fragment. Dental floss was tied between the loop in the
horizontal wire and the ‘J’ hook. The loop was carefully sited to ensure that extrusion occurred along the
long axis of the apical fragment. After one month the
floss tie was replaced with a one-eighth inch elastic:
this was renewed weekly.
Over the following fortnight, the distance between
the hook and loop reduced, and the short elastic was
replaced with elastic chain. After six weeks, the apical
fragment had extruded approximately 3 mm and the
gingival tissues appeared to be healthy (Figure 2). The
root fragment was now fixed by passing a wire ligature between the hook and the horizontal section of
wire.
After three months retention, an additional periodontal procedure was undertaken to restore the
height of the alveolar bone and to recontour the gingival tissues. A partial thickness labial flap and a full
thickness palatal flap were raised and a small osteotomy carried out to recontour the crestal bone. Both
flaps were then repositioned apically and sutured in
place (Figure 3). The patient was prescribed analgesics
(Acetaminophen 750 mg, Johnson and Johnson, São
Paulo, Brazil) and a daily 0.12 per cent chlorhexidine
mouthrinse. The sutures were removed after seven
days and healing occurred without any complications
(Figure 3). The ‘J’ hook was removed and the root
canal prepared for the final post-crown (Figures 4 and
5). Clinical and radiographic examination indicated
that all aesthetic and functional objectives had been
met and that new bone had been deposited in the
socket and on the alveolar crest (Figure 4).
Discussion
Teeth fractured at the level of the marginal gingivae
or below the crest of the alveolar bone are usually
Australian Orthodontic Journal Volume 26 No. 1 May 2010
91
CUOGHI ET AL
(a)
(b)
Figure 3. (a) The root fragment immediately after periodontal surgery. (b) Two weeks later.
(a)
(b)
Figure 4. Periapical radiographs. (a) At the start of extrusion and eight weeks later. (b) After periodontal surgery and the final post-crown.
treated with periodontal surgery and/or orthodontic
extrusion of the apical root fragment. The intention
is to restore the gingival sulcus to approximately
1 mm and the distance between the bottom of the
sulcus and the alveolar crest to about 2 mm. Thus,
3 mm is considered to be the minimum distance
between the top of the alveolar crest and the gingival
margin. In the case we have presented the fracture
occurred approximately 3 mm below the crest of the
alveolar bone necessitating 6 mm of extrusion.
Removing crestal bone without extruding the root
can compromise both the aesthetics (the crown must
be larger) and the crown-root ratio.15 If, on the other
hand, the apical fragment is extruded orthodontically
92
Australian Orthodontic Journal Volume 26 No. 1 May 2010
the root will be shorter, but the dimensions of the
crown will be unchanged and the aesthetics and
crown-root ratio maintained. Whatever therapeutic
procedure is adopted, at the end of rehabilitation the
crown-root ratio should be approximately 1:1.
How does one decide if extrusion of an apical root
fragment is the best course of action? Ideally, only one
or two teeth should be involved and the fracture
should be in the coronal third of the root.12 To determine the suitability of the present case for extrusion
we divided the overall length of the tooth on a long
cone periapical radiograph into eight equal parts. Five
parts corresponded to the root length and three parts
to the crown length. This indicated to us that we
MULTIDISCIPLINARY TREATMENT OF A FRACTURED ROOT
Figure 6. Initial or pretreatment crown-root ratio 3:5 (a) and after the
rehabilitation 3:4 (b). The crown–root lengths were measured on periapical
radiographs.
Figure 5. The final restoration.
could extrude the root 3 to 4 mm and still have a
minimum crown-root ratio of 1:1. The crown was
originally three-eighths of the length of the intact
tooth: after extrusion it was three-sevenths of the
restored tooth (Figure 6).
Upper central incisors have a mean crown length
of 12 mm and a mean root length of 16 mm. Upper
lateral incisors, on the other hand, have a mean
crown length of 9 mm and a mean root length of
15 mm.16 Considering the crown-root ratios of these
teeth, the central and lateral incisors can be extruded
4 and 6 mm, respectively. The upper central incisors
are more likely to be fractured, but upper lateral
incisors have a more favourable crown-root ratio for
extrusion.
Following approximately 3 mm extrusion we retained
the tooth for three months to allow bone to be
deposited behind the extruded tooth and reduce
relapse (Figure 4). We then recontoured the bone to
position the root face 3 mm above the alveolar crest.
Although the root was shorter the new crown-root
ratio was 3:4 and aesthetics were not compromised
(Figures 5 and 6).
More bone may be deposited during slow extrusion
than during rapid extrusion. Providing extrusion does
not exceed 2 mm per month, deposition of new bone
proceeds at a satisfactory rate. It has been reported
that high forces and a faster rate of extrusion, approximately 1 mm per week, were accompanied by
reduced migration of the supporting tissues, less new
bone cervically and ankylosis.17–19
The periodontal fibres, in particular the marginal and
apical fibres, may be ‘stretched’ during extrusion and
remained stretched for some months.20 If a supracrestal fibrotomy is carried out shortly after extrusion
some additional extrusion will occur, but it may be
accompanied by less new cervical bone, gingival recession and loss of periodontal attachment.14,17,21–23
Low magnitude forces in the region of 15 to 30 cN
extrude a tooth slowly and promote bone and periodontal ligament remodelling. Progress should be
monitored clinically and radiographically. The initial
force applied to the root fragment should be used as
a reference value and adjusted according to the root
morphology and speed of extrusion.
The case we have described demonstrates that with a
multidisciplinary approach to treatment, fractures
below the crest of the marginal bone can be treated
successfully. The lateral incisor was extruded with
materials available in many dental practices. Despite
the simplicity of the method, unwanted tipping,
rotation or even contact of the extruding tooth with
adjacent roots may result if the force is applied
without regard to the centre of resistance of the root
fragment.
Corresponding author
Prof. Adj. Osmar Aparecido Cuoghi
Disciplina de Ortodontia - Faculdade de
Odontologia de Araçatuba – UNESP
Rua José Bonifácio 1193
CEP 16015-050
Araçatuba, SP
Brazil
Tel: (+55 18) 3636 3236
Email: osmarorto@terra.com.br
Australian Orthodontic Journal Volume 26 No. 1 May 2010
93
CUOGHI ET AL
References
1.
Turley PK, Crawford LB, Carrington KW. Traumatically
intruded teeth. Angle Orthod 1987;57:234–44.
2. Olsburgh S, Jacoby T, Krejci I. Crown fracture in the permanent dentition: pulpal and restorative considerations.
Dent Traumatol 2002;18:103–15.
3. Trushkowsky RD. Aesthetic, biologic and restorative considerations in coronal segment reattachment for fractured
tooth: a clinical report. J Prosthet Dent 1998;79:115–19.
4. Leroy RL, Asp JK, Raes FM, Martens LC, De Boever JA. A
multidisciplinary treatment approach to a complicated maxillary dental trauma: a case report. Endod Dent Traumatol
2000;16:138–42.
5. Meiers JC, Freilich MA. Chairside prefabricated fiber-reinforced resin composite fixed partial dentures. Quintessence
Int 2001;32:99–104.
6. Andreasen JO, Andreasen FM, Andersson L. Textbook and
color atlas of traumatic injuries to the teeth, ed 4. Oxford :
Blackwell Munksgaard, 2007: p 897.
7. Poi WR, Cardoso LC, Castro JC, Cintra LT, Gulinelli JL,
Lazari JA. Multidisciplinary treatment approach for crown
fracture and crown-root fracture: a case report. Dent
Traumatol 2007;23:51–5.
8. Villat C, Machtou P, Naulin-Ifi C. Multidisciplinary
approach to the immediate aesthetic repair and long-term
treatment of an oblique crown-root fracture. Dent
Traumatol 2004;20:56–60.
9. Padbury A Jr, Eber R, Wang HL. Interactions between the
gingiva and the margin of restorations. J Clin Periodontol
2003;30:379–85.
10. Gargiulo AW, Wentz F, Orban B. Dimensions and relations
of the dentogingival junction in humans. J Periodontol
1961;32:261–7.
11. Turgut MD, Gönül N, Altay N. Multiple complicated
crown-root fractured of a permanent incisor. Dent
Traumatol 2004;20:288–92.
12. Bach N, Baylard JF, Voyer R. Orthodontic extrusion: periodontal considerations and applications. J Can Dent Assoc
2004;70:775–80.
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Australian Orthodontic Journal Volume 26 No. 1 May 2010
13. Ingber JS, Rose LF, Coslet JG. The biologic width – a concept in periodontics and restorative dentistry. Alpha
Omegan 1977;70:62–5.
14. Berglundh T, Marinello CP, Lindhe J, Thilander B,
Liljenberg B. Periodontal tissue reactions to orthodontic
extrusion. An experimental study in the dog. J Clin
Periodontol 1991;18:330–6.
15. Ingber JS. Forced eruption: Part II. A method of treating
nonrestorable teeth – Periodontal and restorative considerations. J Periodontol 1976;47:203–16.
16. Sicher H, Du Brul EL. Anatomia Bucal. ed 8. São Paulo: Ed.
Artes Médicas. 1991. p 511.
17. Sabri R. Crown lengthening by orthodontic extrusion.
Principles and technics. J Periodontol 1989;8:197–204.
18. Minsk L. Orthodontic tooth extrusion as an adjunct of periodontal therapy. Compend Contin Educ Dent 2000;21:
768–70,72,74.
19. Malmgren O, Malmgren B and Goldson L. Orthodontic
management of the traumatized dentition, In Andreasen JO,
Andreasen FM, Andersson L. Textbook and Color Atlas of
Traumatic Injuries to the Teeth, 4th edn. Oxford: Blackwell
Munksgaard, 2007, 669–715.
20. Reitan K. Principles of retention and avoidance of posttreatment relapse. Am J Orthod 1969;55:776–90.
21. Bondemark L, Kurol J, Hallonsten A, Andreasen JO.
Attractive magnets for orthodontic extrusion of crown-root
fractured teeth. Am J Orthod Dentofacial Orthop 1997;
112:187–93.
22. Pontoriero R, Celenza F Jr, Ricci G, Carnevale G. Rapid
extrusion with fiber resection: a combined orthodontic-periodontic treatment modality. Int J Periodontics Restorative
Dent 1987;7:30–43.
23. Lovdahl PE. Periodontal management and root extrusion of
traumatized teeth. Dent Clin North Am 1995;39:169–79.
Editorial
Can an optimal force be estimated?
Dr Brian Lee thinks so. In a carefully executed study
Dr Lee calculated the associations between the lengths
and areas of the roots of the permanent teeth and
found some remarkably high values. He reports the
correlations were improved when the product of
length and width were used, and describes how to use
his data and to obtain optimal rates of tooth movement. This extensive study provides a wealth of data
for the clinician.
Decalcification around orthodontic attachments can
be distressing for patients and clinicians. According to
Drs Uysal, Amasyali, Koyuturk, Ozcan and Sagdic,
amorphous calcium phosphate-containing composites
replace the mineral lost due to decalcification and may
lessen the risk of decalcification in patients with poor
oral hygiene.
The cytotoxicities of separating elastics were investigated by Drs Pithon, Santos, Martins, Romanos and
Araujo using neutral red over periods up to 168 hours.
Both latex and non-latex separating elastics were
investigated and clinicians will be pleased to learn
both types were considered to be biocompatible.
In this latest study, Drs Miles and Weyant compare
the efficiencies of self-ligating and conventional porcelain brackets and report that the self-ligating
brackets were quicker to ‘untie’ and ‘tie’ than conventional brackets and there were no significant differences in the alignment or discomfort experienced
by the subjects.
In a study of Brazilian subjects, Drs Motta, Souza,
Bolognese, Guerra and Mucha report older Brazilians
show less of their upper incisors and more of their
lower incisors than young Brazilians. Some would
argue that this is a good reason for the current concern
about maintaining lower incisor alignment.
Drs Kilic, Catal and Oktay provide norms for the
McNamara analysis for Turkish adolescents. They
found some small gender differences, but conclude
that it may be possible to use the same norms for boys
and girls.
In an electron microscopic study, Drs Bhalla, Good,
McDonald, Sherriff and Cash confirm that the slot
sizes of six self-ligating brackets were larger than the
stated dimension: in some cases by quite large
amounts. They caution that differences between slot
widths and archwire sizes may lead to significant loss
of torque with some prescriptions.
Drs Dause, Cobourne and McDonald investigated the
sensitivity and specificity of the Royal London Space
Planning and Korkhaus analyses. They report both
analyses were clinically sensitive, but the Royal
London Space Planning Analysis lacked specificity.
Readers who are not familiar with these analyses will
find their article interesting and informative.
In an interesting study of indirectly applied cyclic
loading and unloading to the inter-premaxillary
suture, Drs Uysal, Olmez, Amasyali, Karslioglu,
Yoldas and Gunhan report that new bone was
deposited in the expanded suture. They used two
loading cycles and report that the greatest percentage
of new bone was found in the group subjected to the
higher loading cycle. Further studies will investigate
additional loading cycles and whether it is loading or
unloading that is important for the formation of new
bone.
In an EMG study of muscle activity in the upper lip,
Dr Nihat Kilic confirmed that lip activity did not
appear to determine the positions of the incisors. In a
prospective clinical trial, Drs Pandis, Polychronopoulou, Sifakakis, Makou and Eliades examine the
effects of levelling the curve of Spee on the mandibular incisors and arch widths. They report that about
4 degrees of lower incisor proclination accompanied
1 mm of levelling with a straight-wire appliance.
Drs Ang and Dreyer compared the dental changes
produced by two advancement appliances used by
patients with obstructive sleep apnoea. Users of
these appliances will be pleased to note that both
appliances had similar, mild effects on the dentition
and occlusion.
I was unaware that ozone water is used widely to disinfect water systems until I read this article by Drs
Pithon and Santos. They report that ozone water did
not affect the bond strengths of the adhesives they
Australian Orthodontic Journal Volume 26 No. 1 May 2010
95
EDITORIAL
used; a finding of interest to orthodontists and
restorative dentists using these materials.
When the skeletal changes in young Class III patients
treated with combined facemask and intermaxillary
traction were examined, Drs Thiesen, Fontes,
Zastrow and May found that the most significant
changes occurred in the first three months of
treatment.
The bond strengths of a number of different adhesives were not adversely affected when the same selfetching primer was used, according to Drs ScougallVilchis, Zarate-Diaz, Kusakabe and Yamamoto.
96
Australian Orthodontic Journal Volume 26 No. 1 May 2010
The final article in this issue is a case report by Drs
Cuoghi, Bosco, Mendonca, Tondelli and MirandaZamalloa of an incisor with a fractured root. The
tooth was extruded orthodontically and restored,
following periodontal surgery. The authors point out
the advantages of a multidisciplinary approach to
treatment of these challenging cases.
Michael Harkness
Book
reviews
Current Therapy in Orthodontics
Authors: Ravindra Nanda and Sunil
Kapila
Publisher: Mosby Elsevier
(shop.elsevier.com.au)
Price: AUD $236.00
ISBN: 978 0323054607
This book has been prepared in honour of the significant contributions that Dr Ram Nanda has made to
orthodontics throughout his 50 years in education. It
is seen as a collection of contemporary papers on
numerous relevant topics in orthodontics by a group
of professional colleagues who are seen as leaders in
their fields, and to a large extent, have shared their
professional development.
This book does not aim to outline the routine aspects
of diagnosis and treatment planning as seen in most
textbooks in orthodontics, but focuses on some
specific issues which make it compelling reading for
the experienced practitioner and graduate student.
Unlike many textbooks in orthodontics, every chapter
has a unique focus with material that is generally
contemporary in nature, leaving very little for the
reader to gloss over.
The book is divided into four parts, based on issues
in orthodontic diagnosis and treatment, clinical
management of sagittal and vertical discrepancies,
management of adult and complex cases and in Part 4,
a glimpse into the future as to where the profession
stands in embracing molecular techniques.
Part 1 introduces the reader to issues related to quality of life and compliance. The outcome of contemporary orthodontic treatment frequently includes
issues relating to quality of life. In fact, many reviews
of publicly funded healthcare delivery systems now
require this to be considered in evaluating treatment
outcome. These two chapters are thoughtfully pre-
pared and comprehensively referenced. Chapter 3
demonstrates a method of cephalometric analysis,
which challenges the orthodontist to simultaneously
incorporate developmental status into the dynamics of
craniofacial growth. Chapter 4 demonstrates how a
comprehensive assessment of occlusal contact
relationships may assist if developing treatment
need, the outcome of treatment and how this may
relate to orthodontic stability. Chapter 5 is an excellent chapter, which outlines the state of the art in
three-dimensional imaging to evaluate treatment outcomes. This provides an exciting view of what the
clinician may anticipate in the future. Chapter 6 is a
comprehensive outline of issues related to bonding of
appliances with a contemporary strategy to handling
white spot lesions. Chapters 7 and 8 provide a concise
summary of two excellent clinicians’ focuses in recent
years: Dr Sondhi on bracket placement and design
and Dr Zachrisson on aesthetics and biomechanics.
These chapters are excellent complements to their
publications and lecture material.
Part 2 introduces the sagittal and vertical theme with
Chapter 9 presented by William Clark. This is an
excellent summary of Dr Clark’s twin block appliance,
applying some of the significant research findings to
his own personal work. Chapters 10 and 11 present a
comprehensive outline of the effectiveness of noncompliance Class II correctors. In Chapter 11, Dr
Bowman comprehensively outlines how treatment
choices may be based on the treatment objectives,
moreover how appliance effects may be enhanced by
incorporation of temporary anchorage devices.
Chapter 12 gives a brief summary of maxillary
deficiency in the transverse and antero-posterior
planes. In Chapter 13 strategies to enhance protraction, including supplemental temporary anchorage
devices and alternate expansion and contraction
regimes to disarticulate the maxilla, are discussed.
Chapter 14 is a brief overview of the physiology of
mastication and respiration and how this may relate to
the aetiology of open bites.
Chapters 15 and 16 outline biomechanical strategies
which may be considered to address open bites and
Australian Orthodontic Journal Volume 26 No. 1 May 2010
97
BOOK REVIEWS
deep bites, based on differential diagnosis and developing specific individualised goals.
Part 3 begins with a brief chapter demonstrating
treatment of patients with periodontal complications.
It is followed by Chapter 18, which describes a
thought-provoking strategy to maintain midline
diastema closure with creative positioning of the
teeth. Chapter 19 outlines complex goal-oriented
biomechanics to manage some challenging clinical
situations in adults. Chapter 20 discusses the subject
of sleep apnoea and the role of the orthodontist in
both non-surgical and surgical management of this
problem, as orthodontists increasingly receive
referrals for this serious condition. Chapter 21
focuses on the management of the worn dentition
and provides an overview of interdisciplinary planning to achieve optimal results. Chapters 22 to 24
focus on temporary anchorage appliances, their indications, placement and biomechanical application.
These excellent chapters will facilitate the comprehension of how these adjuncts may be used effectively. The objective of decreasing treatment time is
the focus of many clinicians’ research; distraction of
the canine was introduced nearly a decade ago and
numerous physical, chemical and surgical strategies
have been suggested. Chapter 25 outlines the technique,
which on the surface appears quite challenging, but it
has provoked further developments in this field.
Part 4 begins with chapters that are well-written and
easy to comprehend on the biological mechanisms in
tooth movement. Comprehension of these pathways
has opened the door to understanding how clinicians
may improve treatment effectiveness without undesirable consequences such as root resorption. A final
chapter outlines the future of tissue engineering; as
clinicians become more enthusiastic of the impact
that these procedures will have on contemporary
medicine.
Drs Ravindra Nanda and Kapila should be congratulated on establishing such a collaborative effort to
produce a state of the art book. In summary, this
book is clinically focussed with extensive illustrations
with particular emphasis on biomechanics, as you
would expect from Drs Nanda and Kapila. This book
updates many new exciting developments in orthodontics. It should grace the personal libraries of all
graduate students and practising orthodontists.
Mithran Goonewardene
98
Australian Orthodontic Journal Volume 26 No. 1 May 2010
Self-Ligation in Orthodontics
Authors: Theodore Eliades and Nikolaos
Pandis
Publisher: Wiley-Blackwell, 2009
(www.wiley.com)
Price: AUD $170.00
ISBN: 9781405181907
Clinical orthodontics has been inundated with discussion, promotion, hype and controversy about selfligating brackets for the past 10 years or so.
Extraordinary claims have been made that a little clip
or slide instead of a piece of wire or elastomeric ring
can reduce the need for surgery, extractions, expansion devices etc. Other claims of faster treatment, less
discomfort, better hygiene, less root resorption make
these brackets seem highly desirable. If these claims
are true, the much higher price paid for them would
be worth it.
Orthodontists with a healthy skepticism about claims
made for more expensive products than they currently use are right to want high quality evidence to
support the various claims. Even if all the claims
made are not substantiated, perhaps there are some
real advantages in using the brackets that would make
their use beneficial. Here is a text book that may
provide the answers to those considering using selfligating brackets, or seeking to know how to use them
more efficiently.
The authors’ preface notes the hype around the
brackets, with the industry organising conferences
and pushing an agenda. This has resulted in ‘statements and claims which contradict fundamental
principles of mechanics and craniofacial biology,
actually doing an injustice to a bright idea for a new
appliance’. The stated aim of this book is to ‘comprehensively review self-ligation and summarise the evidence available in the literature’. There are indeed
many references right up to publication date quoted
at the end of each chapter.
There are also many chapters of background texts
written by eminent scholars. These cover bracket
material properties, essentials of clinical research
design, molecular response of periodontal ligament
BOOK REVIEWS
and bone to loading, root resorption, and attachment
of oral microbiota to dental surfaces. These background chapters are quite detailed and relate to
dentistry and oral biology in general, not specifically
to self-ligating brackets. These chapters occupy about
one third of the book and can act as a refresher or
update on the basic topics. However, to get full
understanding, some of the chapters would require
significant extra study by any clinicians who have
been out of dental school a few years.
The book starts with a review of the development and
evolution of light force and self-ligating orthodontics.
There is a listing of the various brackets available at
the time of publication, and a brief review of some of
the features of the most well-known brackets. There
is some discussion of the active and passive bracket
concept. A more comprehensive description and
comparison of the features of the main brackets on
the market would give the reader a better understanding and ability to evaluate which bracket might
suit his or her practice.
The short chapter on the biomechanics of selfligation describes some of the authors’ laboratory
studies the forces generated on regular and different
self-ligating brackets. Some predictable differences
are found between the various brackets in forces
applied in different planes of space. For instance,
passive self-ligating brackets with a rigid closing
mechanism deliver higher forces to the tooth in
bucco-lingual and rotational movements than do
brackets with active spring clips or elastomeric ties.
There is discussion about the loss of stiffness that
has been reported in the spring clips of the active
brackets, In-Ovation R, but not Speed. The authors
say that ‘the performance and aging of the nickeltitanium clips significantly depend on the alloy composition and the associated phase transformations’. In
fact, the clip on the In-Ovation bracket is cobaltchrome and only the Speed is nickel-titanium.
The final chapter on treatment mechanics with selfligating brackets is where the reader would be looking
for tips and ideas for using the advantages of selfligating brackets to improve treatment progress and
outcomes. Instead, the chapter is a brief and basic
primer on orthodontic diagnosis, treatment planning,
mechanics and retention, with only a couple of points
about doing things differently with self-ligating
brackets. There is no discussion of the better rotational control we see when using sliding mechanics,
different anchorage setups that can be used due to
lower forces required in retraction, or the use of
specially designed archwires to complement the
action of the spring clips.
In short, if you are looking for a book that gives a
comprehensive overview of the features and possibilities of the different self-ligating brackets, along with
the most efficient ways to use them, you will need to
look elsewhere.
Paul Schneider
Minor Tooth Movement with Microimplants
for Prosthetic Treatment
Author: Hyo-Sang Park
Publisher: Dentos Australia Pty Ltd
Email: dentos1@optusnet.com.au
Price: AUD $200.00
ISBN: 978 89 956605 4 6
This hard covered book is published by Dentos Co
Ltd., manufacturers of the micro-implants used by
the author. The book is well laid-out with high
quality photographs and illustrations in all sections.
The original text was presumably written in Korean
and has been translated into English. This has the
effect of confronting the reader with occasional, often
distracting, errors of expression.
The book is divided into seven chapters. The
first chapter describes the surgical procedure recommended by Dr Park. It is a detailed description of
technique, also discussing the pros and cons of
self-tapping and self-drilling micro-implants.
The anatomical considerations in the selection of
implant sites are described and a brief section on
complications is included.
The second chapter is on molar uprighting. The
extrusive side effects of molar uprighting are discussed, along with options for micro-implant placement to control the vertical effects. The concept of
indirect anchorage, where the implant is attached to
anchor teeth that are then used to place load on the
target tooth or teeth, is introduced in this section. An
interesting innovation described is the use of two
Australian Orthodontic Journal Volume 26 No. 1 May 2010
99
BOOK REVIEWS
adjacent micro-implants to increase stability. Several
cases are presented to illustrate the techniques
discussed.
The next chapter, the largest, is on molar intrusion.
Several case reports are used to describe methods for
intruding various teeth and combinations of teeth.
These include maintaining the vertical position of
teeth after the loss of opposing teeth, and intrusion of
one and two maxillary molars. The use of a combination of buccal and palatal micro-implants is shown,
along with a strategy to control the transverse side
effects of intrusion. The intrusion of mandibular
molars is briefly described, including the difficulty
experienced because of the inability to place
mandibular lingual micro-implants.
The fourth chapter describes the protraction of
molars; the mandibular and maxillary molars discussed separately. Micro-implant placement options
are described with clinical examples. In some cases
indirect anchorage was used. For direct protraction an
orthodontic bracket was attached to adjacent microimplants with a sectional archwire.
The next section describes forced eruption. Two
interesting cases are described: one using twin microimplants with an orthodontic bracket and archwire to
extrude a fractured maxillary canine, and the other to
extrude a fractured upper central incisor. Both cases
are described and illustrated with radiographs and
photographs. A palatally impacted canine case is
adequately managed, using the same technique.
A short penultimate chapter discusses the redistribution of space for dental prostheses.
The final chapter discusses the ‘nuts and bolts’ of
micro-implants including such topics as success rates,
complications, force levels, osseointegration and solutions when initial stability is not obtained. This book,
while being the opinion of a single author, has value
because of Dr Park’s extensive experience with these
adjuncts. Each section has a reasonable number of
references, mostly from recent publications. The
illustrations are of a very high quality, making the
description of techniques easy to understand.
While the title of the book suggests a focus on prosthetic treatment, it can be considered a useful
resource for all orthodontists using micro-implants
for any purpose.
Joe Geenty
100
Australian Orthodontic Journal Volume 26 No. 1 May 2010
Dental Practice: Get in the Game
Editor: Michael Okuji
Publisher: Quintessence Books 2010
(www.quintpub.com)
Price: USD $48.00
ISBN: 978 0 86715 492 4
Dr Okuji has edited a book which attempts to fill a
well-known gap in dental undergraduate education –
understanding the business environment and setting
up or buying a practice and getting that first job. And
I would have to say this is an excellent publication for
that purpose.
Like many textbooks with chapters by different contributors, this book is very good in parts. There are 10
chapters that cover everything from ‘Choosing a Path’
through to business plans and valuation methods,
with some useful appendices. The chapters that work
less well, particularly for Australian dentists, include
the ones on dental practice regulations, managed care
and insuring your practice. This is predominantly
because of the large differences in legislation and
business regulations.
A few other chapters work less well also, but for different reasons. The chapter on communications is not
long enough to develop adequately – with only one
reference to Dr Coveys' celebrated ‘Seven habits of
highly effective people’. But I imagine that only so
much can be presented in a single book covering such
a large area of interest. More references would have
helped the reader explore these areas. Chapter 7, on
understanding basic finances is perhaps the opposite,
with many pages devoted to this and the introduction
of some complex concepts from corporate finance
such as net present value, which while important,
might be a stumbling block for young dentists.
There is a necessarily long section on taxation for
USA residents.
However, the other chapters more than make up for
these small deficiencies. Chapter 1 is an excellent
structured guide for the young dentist on how to
decide which way to go. It has many break-out boxes
of anecdotes and advice and these alone would be
worthwhile for young general or specialist dentists.
BOOK REVIEWS
The chapters on finding a job, purchasing a practice
and starting a new practice are excellent.
Dr Okuji has edited and written a very good reference
book for younger dentists to read about their practice
future. I hope that such a book is used in the undergraduate curriculum here and the USA.
Brad Wright
Introduction of Innovative Orthodontic
Concepts Using Microimplant Anchorage
Author: Haruyuki Hayashi
Publisher: Dentos Australia Pty Ltd
Email: dentos1@optusnet.com.au
Price: AUD $75.00
ISBN: 978 89 956605 2 2
Technical issues of placement and minimising and
overcoming problems are dealt with at the end of the
text, also offering some handy tips. However, in what
is a rapidly growing and evolving area of clinical
practice there are possibly some superseded concepts, most notably the suggested timing of loading
in relation to placement.
Overall, this booklet is a worthwhile stimulus for
devising relatively simple solutions for problems to
aid oral restoration, but it may not offer much that is
truly new to the orthodontist who has taken an interest in the use and application of micro-implants
(miniscrews, TADS) over recent years.
Steven Langford
This 75-page booklet has been translated into English
(except for the bibliography!), but it is easy-to-read
and well-illustrated, making for a short read also.
The introduction is dated August 2006 and indicates
that Dr Hayashi has been involved in micro-implant
anchorage for more than 15 years. The aim of the
publication is to address possible uses of microimplant anchorage for minor tooth movements to
facilitate oral rehabilitation without involving fullbracketed orthodontic appliances. It is primarily
directed at the general practitioner or restorative specialist, but certainly offers some innovative and
thought provoking ideas as suggested by the title.
There are apparently further publications by the
author addressing more complex and specific issues,
either planned or in print.
Australian Orthodontic Journal Volume 26 No. 1 May 2010
101
Recent
publications
Abstracts of recently published papers reviewed by the Assistant Editor, Craig Dreyer
Impaction and retention of second molars:
diagnosis, treatment and outcome.
A retrospective follow-up study
C. Magnusson and H. Kjellberg
Failure of tooth eruption or tooth impaction is a common problem affecting 20 per cent of the population.
While the incidence of second molar impaction is low,
knowledge regarding the aetiology is largely based on
case reports and a few clinical studies. The treatment
of these teeth often requires a multidisciplinary
approach and interdisciplinary discussion in deciding
the best treatment plan. The authors aimed to
describe the outcome of treatment in patients experiencing second molar impaction and to report the outcome of no treatment.
The retrospective, longitudinal follow-up study identified after exclusion, 87 patients (42 males, 45
females) with a mean age of 15 years and with 166
impacted second molars. One hundred and eight of
the second molars were treated, of which 79 were followed over periods ranging from 1 to 5 years. The
impacted molars were diagnosed from CT scans,
panoramic or periapical radiographs. Study casts and
photographs were used to assess other parameters
related to the occlusion. The outcome of treatment
and the outcome of no treatment was assessed, with
treatment designated a failure if the impacted second
molar did not erupt 12 months after surgical intervention. If a second molar was extracted, success was
defined by the acceptable eruption and position of the
third molar.
Of the diagnosed impacted second molars, 80 per cent
were either orthodontically or surgically treated and,
of those, less than half erupted into a proper position.
Of the 20 per cent which remained untreated, slightly
fewer than half erupted favourably. The most successful form of treatment was the surgical exposure of the
impacted molar and the least successful treatment
used the third molar to replace the second molar
102
Australian Orthodontic Journal Volume 26 No. 1 May 2010
following its extraction. The authors concluded that
no matter what the treatment, success could not be
assured, but surgical exposure offered the best option.
Unfortunately, the severity of the impactions was not
detailed and so a solid and reliable conclusion
becomes more difficult. The clinical experience of the
reviewer indicates that the more vertical the
impaction, the more likelihood of success, and the
more horizontal the second molar impaction, the
more problematic the management. The article would
have been improved by an indication of the severity
of the impaction and its relationship with treatment
outcome.
Angle Orthodontist 2009; 79: 422-427
Exposure of unerupted palatal canines: a
survey of current practice in the United
Kingdom and experience of a gingivalsparing procedure
H.R. Spencer, R. Ramsey, S. Ponduri and P.A. Brennan
There is argument regarding the best surgical procedure for the exposure of palatally impacted canines.
Surgical exposure may either be open or closed
depending on diagnostic needs, but there has been
reported surgical variation among operators. In order
to determine the current practice in the UK, a questionnaire was sent to consultant oral and maxillofacial
surgeons. The questionnaire described pictorially, four
different exposure procedures and respondents were
asked to indicate which surgical procedure they used
and preferred.
The four procedures were:
1. A full thickness palatal mucoperiosteal flap with
excision of a wedge of tissue over the unerupted
canine to the gingival margin of the flap, prior to its
replacement.
2. A full thickness flap as before, but with only a
window of tissue removed over the unerupted canine.
RECENT PUBLICATIONS
3. A gingival-sparing approach involving the removal
of tissue over the crown of the unerupted canine and
the application of a periodontal dressing.
4. A full thickness palatal gingival margin flap and the
bonding of an orthodontic attachment with gold
chain affixed. The flap is subsequently replaced without the excision of any soft tissue (closed exposure).
The respondents had an opportunity to annotate
their preferred procedure if the above four were not
practised. There were 343 replies to 565 questionnaires and, as expected, there was extreme variation
among the surgeons. Two-thirds of the respondents
only performed one procedure, either 1 (wedge excision) or 4 (closed exposure). Half of the respondents
included procedure 4 as one of the techniques
employed. Seventy-one per cent included the open
procedure as a preferred technique. Only 9 per cent
of respondents avoided the gingival margin of the
adjacent teeth during the canine exposure. Nevertheless, the authors recommended procedure 3 as the tissue-sparing technique of choice. The premise of the
technique was that the canine would erupt spontaneously after the removal of the overlying tissues. The
technique was quick and minimally invasive but it
was noted, with concern, that the technique was used
by so few.
British Journal of Oral and Maxillofacial Surgery 2009:
doi: 10.1016/j.boms.2009.08.032
females) with 390 impacted third molars referred for
surgical removal. The molars were in submucosal
positions, either partially or totally impacted in bone.
Root formation had been completed, there was no
associated pathology and patients with uncontrolled
systemic disease or local infection were excluded.
The position, morphology and surgical technique
were recorded on 84 molars assessed by digital
panoramic radiographs and 306 molars assessed by
conventional panoramic radiography. Four assessors
of varying experience compared the presurgical data
with the surgical findings and established diagnostic
precision. There were statistically significant benefits
and precision in using the digital radiographs for
presurgical evaluation of the third molars. The
conventional panoramic film distorted the position
and morphology of the molar, which affected the
presurgical strategy of the less experienced surgeons.
Surgeon experience had a profound influence on
diagnostic planning. It was concluded that digital
panoramic radiography offered significantly
greater diagnostic advantages over conventional
radiography.
International Journal of Oral Maxillofacial Surgery 2009; 38:
1184–1187
A review of the diagnosis and management
of impacted maxillary canines
M.M. Bedoya and J.H. Park
Diagnostic predictability of digital versus
conventional panoramic radiographs in the
presurgical evaluation of impacted
mandibular third molars
E. Ferrús-Torres, J. Gargallo-Albiol, L. Berini-Aytés and
C. Gay-Escoda
To date, panoramic radiographs are the most widely
used radiological diagnostic technique in dentistry.
There are several limitations with this two-dimensional approach to diagnosis, which often necessitates
the use of complementary films. With improvements
and the advent of digital radiology, conventional
panoramic radiology is being replaced, but questions
remain regarding the diagnostic quality of digital
images. The authors designed a prospective study to
compare the diagnostic predictability of conventional
panoramic radiographs with digital radiographs in
the presurgical assessment of impacted third molars.
The study assessed 287 patients (125 males, 162
This article is a literature review which deals with the
clinical and radiographic diagnosis of impacted maxillary canines. In addition, the authors searched the
literature to determine the types of interceptive treatment (surgical and orthodontic) used to prevent or
treat canine impaction. The literature was gathered
from clinical and radiographic studies as well as case
reports, and only studies pertaining to the prevalence,
aetiology and diagnosis of impacted canines were
selected. Included were the most recently published
articles, which described the orthodontic and surgical
techniques of management.
The review covers in overview, the incidence, possible
aetiology and sequelae of canine impaction as well as
the clinical and radiographic diagnostic procedures
involved in management. Interceptive treatment is
explored and limited to deciduous canine extraction
while the orthodontic and surgical management is
described more comprehensively. However, there is
Australian Orthodontic Journal Volume 26 No. 1 May 2010
103
RECENT PUBLICATIONS
little about the significant treatment difficulties that
may arise and this, given that the review has been
written for general practitioners, is hardly surprising.
The authors conclude that impacted canines are a
common occurrence that is best managed by early
detection and timely interception. The common
treatment of surgical exposure and orthodontic elevation to guide the canine into place is an over-simplification of management and denies the problems and
difficulties that often arise.
Journal of the American Dental Association 2009; 140: 1485-1493
Wisdom teeth: mankind’s future third
vice-teeth?
D-H. Zou, J. Zhao, W-H. Ding, L-G. Xia, X-Q. Jang and
Y-L. Huang
The science of tissue engineering has proven to be
useful for dental tissue and whole-tooth regeneration
strategies. The recent identification of postnatal dental
stem cell populations suggests that bioengineering
approaches may be used to regenerate a variety of
dental tissues and even entire teeth, provided that an
appropriate seed cell is identified. Autologous tooth
germ cells are multipotent stem cells that have the
capability of differentiating into ameloblasts, odontoblasts, cementoblasts and alveolar bone providing
almost any tooth tissue. The authors identified that
third molars might be extracted for a variety of
reasons and provide a strategy for the replacement of
permanent teeth in later life by the prior harvesting of
third molar stem cells. The concept involves the
salvaging of germ cells from a young patient
whose third molars are in the early stages of development. The extracted tooth germ is cryopreserved in
liquid nitrogen and an electronic database of material
established and maintained. In later life at a time of
tooth loss, the patient’s tooth germ cells may be
located and multipotentiality identified, to produce a
tooth with specific characteristics to the tooth requiring replacement. The addition of growth factors and
scaffold materials would guide the formation of the
new tooth as it is seeded in an intra-arch space.
The authors reveal how successful innovations in
dentistry may be guided by advances in basic research
and close partnerships between researchers and clinicians. This article heralds a dental future that is not
that far distant provided philosophical and ethical
considerations can be overcome.
Medical Hypotheses 2010; 74: 52-55
104
Australian Orthodontic Journal Volume 26 No. 1 May 2010
Orthodontic management of a patient with
impacted and transposed mandibular
canines
R.C. Almeida, F.A.R. Carvalho, M.O.A. Almeida and
J. Jr Capelli
Ectopically erupting and impacted canines may be
found in transposition with neighbouring teeth. The
authors of this article provide a case report of
impaction of both mandibular canines with their
adjacent lateral incisors. The patient was a 10 yearold female with good facial proportions and a Class I
bimaxillary protruded malocclusion. Radiographically, both lower permanent canines were impacted
between the central and lateral incisors and the lower
right second premolar was extremely hypoplastic and
unerupted. The treatment aims were to improve the
patient’s dental appearance by creating space for the
unerupted canines. This initially occurred by the
placement of coil springs bilaterally between the
incisors using fixed appliances supported by a lingual
arch. Even though there was some space distal to the
lateral incisors, it became apparent that additional
space would be required. This was created by the
extraction of the lower left lateral incisor which left
the patient, at deband, with Class I buccal segments,
a ‘normal’ overbite and overjet and dental midlines
that did not coincide. The upper arch was simply
aligned. The authors achieved a satisfactory result and
indicated that transpositions often should not be
corrected from a cost-benefit viewpoint.
Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and
Endodontics
2009;08:e26-e32
Assessment of the associated symptoms,
pathologies, positions and angulations of
bilateral occurring mandibular third molars:
is there any similarity?
Z.Z. Akarslan and C. Kocabay
As the most common dental impaction, an incompletely erupted third molar often gives rise to
symptoms and pathologies, including pericoronitis,
pain, swelling, distal caries, bone loss and many
others. The eruption status, position and angulation
of the tooth reportedly have an impact on these
symptoms. The aim of the article was to evaluate and
establish possible similarities between associated
symptoms, pathologies, position and angulation
types on bilaterally occurring mandibular third
molars in young adult patients.
RECENT PUBLICATIONS
Clinical and radiographic examinations were performed on 342 patients (167 females, 175 males)
aged between 20-25 years (Mean: 22.2, SD: 1.8).
Eruption status, mucosal and bony coverage type,
presence of pain, pericoronitis, suppuration, ulceration, caries, bone loss, root resorption, cyst or
tumour formation was investigated and recorded.
Patients having one completely or partially erupted
mandibular third molar were classified as Group 1
while patients with bilaterally impacted mandibular
third molars were placed in Group 2.
No significant difference was found between the
symptoms and pathologies related to the mandibular
right and left third molars among both groups and
genders. In addition, no significant difference was
found between the right and left mandibular molars
in the assessment of mucosal coverage type, bony
coverage type and position in either group. However,
gender had an influence on bony coverage type and
ramus distance of both molars in Group 2. This was
ascribed to a difference in the size and anatomy of the
mandible in females. In the total sample, symmetry
was present for horizontal or distoangular, and vertical or distoangular angulations in Group 1 and
Group 2. Gender was also found to have an influence
on angulation symmetry. The authors concluded that
similarity was evident between the symptoms and
pathologies related to bilaterally impacted third
molars; however, symmetry in position and angulation differed according to eruption status, angulation
type and gender. It was concluded that this information provided assistance to surgeons in their
evaluation of third molars for extraction.
World Journal of Orthodontics 2009; 10:345-349
Australian Orthodontic Journal Volume 26 No. 1 May 2010
105
New
products
Interproximal diamond strips
topsOrtho practice management software
Ortho Technology’s new
range of perforated interproximal diamond strips are
designed for interproximal
stripping, shaping and contouring. According to the
manufacturer, the perforated strips are more flexible than solid
strips and provide better visibility and control. The strips are
colour-coded and available in two widths, narrow and wide.
topsOrtho is a Mac OS X practice management programme
designed by a practising orthodontist. The programme includes
all necessary software: practice
management, imaging, word
processing, backup software and a SQL database. Just one
server at a main office also serves satellite offices, with no
impact on speed.
For more information on the range of interproximal strips,
diamond burs and diamond discs, contact Ortho Technology
Pty Limited.
Freecall: 1800 678 407
Website: www.orthotechnology.com
For further information contact topsOrtho
Email: sales@topsOrtho.com
Website: www.topsOrtho.com
InVu aesthetic brackets with Readi-Base
pre-applied adhesive
InVu aesthetic brackets by TP
Orthodontics have colour-matching technology that enables the
brackets to blend with individual
teeth, and a pre-applied adhesive
for easy application. The latter is
claimed to reduce chair-time and
prevent brackets from drifting
during placement. According to
the manufacturer, the brackets are robust, have excellent
aesthetics, low friction and debond easily.
For further information contact TP Orthodontics
Tel: 1800 643 055
Email: tpaus@tportho.com
topsCephMate digitising software
This software allows the user
to quickly place cephalometric
landmarks, trace, analyse,
measure and perform STO
and VTO simulations in a
single window. Key features
include the ability to adjust
landmarks without re-digitising
and realistic, live soft tissue morphing. CephMate works with
any X-ray imaging software or digital camera.
For further information contact topsOrtho
Email: sales@topsortho.com
Website: www.topsOrtho.com
106
Australian Orthodontic Journal Volume 26 No. 1 May 2010
Damon Clear Bracket
Ormco’s new Damon Clear brackets
are polycrystalline alumina brackets.
They are impervious to staining and
discolouration, combine the lowfriction properties of passive self-ligation technology and have good
aesthetics, according to the manufacturer. They provide full rotation control and the Spin-Tek slide
facilitates fast, comfortable wire changes and adjustments.
For further information contact Ormco Pty Limited
Tel: 1800 023 603 or your Ormco Territory Manager
Clear Debonding Tool
The New Damon Clear Debonding Tool from Ormco enables
quick, pain-free debonding of the
Damon Clear bracket, ac-cording
to the manufacturer. The wedge
of the instrument is positioned on
the occlusal side of the bracket
and the instrument jaws placed
behind the gingival and occlusal
tie wings. When the instrument
handle is squeezed, the wedge
engages the crown and the
bracket peeled from the tooth.
For further information contact Ormco Pty Limited
Tel: 1800 023 603 or your Ormco Territory Manager
New products are presented as a service to our readers, and
in no way imply endorsement by the Australian Orthodontic
Journal.
Orthodontic
calendar
2010
June 15-19
86th Congress of the European Orthodontic Society, St.
Bernardin Adriatic Resort and Convention Centre, Portoroz,
Slovenia.
Website: www.eos.2010.si
Email: info@eos2010.si
June 30 – July 3
New Zealand Association of Orthodontists’ Biennial Conference,
Hotel Grand Chancellor, Christchurch, New Zealand.
Website: www.conference.co.nz
July 1-3
4th Bali Orthodontic Conference and Exhibition, The Ayodya
Resort, Nusa Dua, Bali.
Website: www.boce5.ikorti-iao.org
Email: bali_ortho@yahoo.com
July 8-11
European Society of Lingual Orthodontics Congress, Queen
Elizabeth II Conference Centre, Westminster, London.
Website: www.eslo-congress.com
August 2-3
Association of Philippine Orthodontists’ 7th Biennial National
Orthodontic Congress, Hotel InterContinental Manila, Makati
City, The Philippines.
Website: www.apo.com.ph
August 18-21
XIII International Orthodontic Congress of the Chilean Orthodontic
Society, Centro de Eventos Casa Piedra, Santiago, Chile.
Website: www.sociedadortodonciachile.org
Email: sortchile@sociedadortodonciachile.org
September 23-25
62nd Annual Scientific Session of the Canadian Association of
Orthodontists, Whistler, British Columbia, Canada.
Website: www.cao-aco.org
November 25-27
Societa Italiana di Ortodonzia’s 22nd International Congress,
Florence, Italy.
Website: www.sido.it
December 11-12
Taiwan Association of Orthodontists’ 2nd World and 9th Asian
Implant Orthodontic Conference, Taipei International Cenvention
Center, Taipei, Taiwan.
Website: www.wioc2010.org.tw
Email: tao.taiwan@msa.hinet.net
December 17-19
Indian Orthodontic Society’s 34th Indian Orthodontic Conference,
Mangalore, India.
Website: www.iosweb.net
Email: rohanmasc@yahoo.com
2011
March 4-6
Australian Society of Orthodontists’ Foundation for Research and
Education Meeting, Melbourne, Australia.
Website: www.aso.org.au
June 19-23
87th Congress of the European Orthodontic Society, Istanbul,
Turkey.
Website: www.eso2011.com
2012
September 18-21
British Orthodontic Society Conference, Brighton, United Kingdom.
Website: www.bos.org.uk
February 11-14
23rd Australian Orthodontic Congress, Perth, Western Australia,
Australia.
Website: aso2012perth.com
September 20-22
South African Society of Orthodontists Conference, Newlands
Conference Centre, Cape Town, South Africa.
Website: www.saso.co.za
November 23-26
8th Asian Pacific Orthodontic Society and the 8th Asian Pacific
Orthodontic Conference, New Delhi, India.
Website: www.iosweb.net
For a list of meetings and links to websites of national and international orthodontic societies, visit the World Federation of Orthodontics, www.wfo.org
For inclusion in the Australian Orthodontic Journal please contact: Dr Tony Collett Tel: (+61 3) 9756 0519
Email: tonycol@netspace.net.au
Australian Orthodontic Journal Volume 26 No.1 May 2010
107
Directory
Australian Society of Orthodontists
Secretariat
PO Box 576, Crows Nest, NSW 1585
ASO Federal Council
President
Mike Razza: mike.razza@uwa.edu.au
Vice President
Chairman: Stephen Moate
sm@nso.net.au
23rd Congress Organising Committee (2012)
Chairman: Howard Holmes
braces@iinet.net.au
24th Congress Organising Committee (2014)
Steven Langford: ortho@adam.com.au
Chairman: Marie Reichstein
reichstein@ozemail.com.au
Secretary
Constitution Committee
Carl Sim: csim@cyllene.uwa.edu.au
Treasurer
Chairman: John Cameron
info@cameronorthodontics.com
Crofton Daniels: croftondaniels9@gmail.com
Education/Membership Advisory Committee
Secretary-Elect
Andrew Toms: aptoms@internode.on.net
Chairman: Mithran Goonewardene
mithran.goonewardene@uwa.edu.au
Treasurer-Elect
Foundation for Research and Education
Simon Freezer: freezer@chariot.net.au
Councillors
Peter Lewis: pjlewis@bigpond.com
Pat Hannan: phan4111@bigpond.net.au
Tony Collett: tonycol@netspace.net.au
Presidents and Secretaries of ASO State Branches
New South Wales
President: Stephen Duncan: sld@ortho-x.com.au
Secretary: Stephen Moate:sm@nso.net.au
Victoria
President: Tracey Shell: tracey@bigpond.net.au
Secretary: Kylie Moseling: kylie.moseling@gmail.com
Chairman: John Owen
john.owen@owenorthodontics.com.au
Orthodontic Services Committee
Chairman: Tony Collett
tonycol@netspace.net.au
Give a Smile Committee
Chairman: T. Crawford
ted@tedcrawford.com.au
Communications and Information committee
Chairman: Ronda Coyne
rondac@ozemail.com.au
Recent Graduates Committee
Queensland
Chairman: Matthew Foo
foo@netspace.net.au
President: Grant Hamilton-Ritchie: ippyortho@westnet.com.au
Secretary: Claylia Ward: brortho@bigpond.net.au
Chairmen/Heads of Academic Departments
South Australia
University of Adelaide
President: Jonathan Ashworth: jashworth@adam.com.au
Secretary: Darren Di Iulio:ddiiulio@tpg.com.au
Professor Wayne Sampson
wayne.sampson@adelaide.edu.au
Western Australia
University of Melbourne
President: Fiona Hall: fiona-graham@bigpond.com
Secretary: Kevin Murphy: kmurphy@amnet.net.au
University of Queensland
TBA
ASO Committees 2010-2012
Dr Shazia Naser-ud-Din
s.naseruddin@uq.edu.au
Appeal Committee
University of Sydney
Chairman: Craig Dreyer
craig.dreyer@adelaide.edu.au
Professor M. Ali Darendeliler
adarende@mail.usyd.edu.au
Archival Committee
University of Western Australia
Archivist: Grant Keogh
grantkeogh@hotmail.com
Associate Professor M. Goonewardene
mithran.goonewardene@uwa.edu.au
Australasian Orthodontic Board
Chairman: Stephen Langford
ortho@adam.com.au
Journal Committee
Editor: Michael Harkness
michael-harkness@xtra.co.nz
Awards Committee
Chairman: David Thornton-Taylor
dttaylor@tpg.com.au
Cleft Lip and Palate Reference Committee
Chairman: Kit Chan
orthob@totallyortho.com.au
108
Communications and Information Committee
Australian Orthodontic Journal Volume 26 No. 1 May 2010
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Allied Associations
Australian Dental Association
Federal Secretariat: Executive Director, Neil Hewson
www.ada.org.au
World Federation of Orthodontists
President: Athanasios E. Athanasiou
www.wfo.org
New Zealand Association of Orthodontists
President: P. Fowler
peter@braces.co.nz