22 ____________________________________________________________________________________ Iraqi Orthod J 1(2) 2005
Tooth Size Discrepancy of the Permanent Dentition
in Class II div. 1 Malocclusion with Crowding or Spacing
Mushriq F. Al-Janabi,a Hayder F. Saloom,a and Nameer T. Al-Taai a
Abstract: A proper relationship of the total mesiodistal width of the maxillary dentition to that of the
mandibular dentition will favor an optimal post treatment occlusion, the purpose of this study is to compare
the mesiodistal crown dimension and tooth size discrepancy in subject with class II div.1 malocclusion with
spacing or crowding in the upper and lower arches. Sixty pairs of dental casts were obtained (30 crowding,
30 spacing) were measured and analyzed, the results indicates males generally have greater mesiodistal
crown dimension than females in both crowding and spacing groups, and there was a significant difference
between both groups with greater mesiodistal width for the crowding group, and non significance
difference regarding tooth size analysis ( Bolton ratio).
Keywords: Anterior facial height, tooth size (Iraqi Orthod J 2005; 1(2): 22-25).
T
reatment planning should always take into
consideration a discrepancy of the tooth size
ratios and should include compensating esthetic
procedures such as composite bonding. 1
Tooth size ratios represent a valid diagnostic tool
that allow for an educated prediction of treatment
outcomes and may also limit the necessity for diagnostic
setups for complex cases. A proper relationship of the
total mesiodistal width of the maxillary dentition to the
mesiodistal width of the mandibular dentition will favor
an optimal post treatment occlusion.2
It is known that several etiologic factors are
associated individually or in groups to dental crowding
in the permanent dentition.3 Mesiodistal tooth width is
considered a primordial etiologic factor in space
anomalies, which together with tooth width discrepancy
may cause malocclusion.4-5
Differences between mesiodistal tooth width in
crowded and non-crowded dentitions have been
reported in several studies.5-8 but only few of these
studies analyzed mesiodistal tooth width collectively
instead of individually.6
Some of the studies showed that Bolton anterior
ratio was significantly higher in the group with lower
incisal crowding compared with the group with good
alignment.9
The space available in the dental arches is not,
however, a function only of the size and morphology of
the bony bases of the jaws, but is also associated with
the size of the teeth, in persons whose teeth have large
mesiodistal dimensions for example crowding is more
common in persons with smaller teeth.10
Therefore this study was designed to evaluate
and measure tooth size ratios in the permanent dentition
of Cl. II div. 1 malocclusion patients having crowding
or spacing.
a
B.D.S., M.Sc.; Department of Orthodontics, College of Dentistry,
University of Baghdad.
MATERIALS AND METHODS
The data of this study were derived from dental
casts, of 60 patients attending the college of dentistry
university of Baghdad and some of the private clinics,
with an age range of 14-22 years, those patients have no
history of orthodontic treatment, and they have full
complement of permanent dentition excluding the 3rd
molars, with Cl. II Div. 1 Angle's classification, the
teeth were caries free with no gross restoration or any
anomaly in the size, shape. Dental arch discrepancy was
considered as the difference between the available and
required space in each dental arch, according to dental
arch discrepancy the sample was divide into two groups;
crowding group (15 males, 15 females), spacing group
(15 males, 15 females).
The measurement were made directly on the dental
casts, which were taken using alginate impression
materials and poured with plaster of Paris.
The greatest mesiodistal measurement were taken
from the greatest mesiodistal width of the teeth from the
anatomic mesial contact area to the anatomic distal
contact area to the nearest 0.1 mm by mean of sharp end
vernier with sharpened peaks parallel to the long axis of
the crown.
Tooth size ratios were calculated in the groups using
formulas proposed by Bolton.1,4
Overall ratio = Sum mandibular “12” X 100
Sum maxillary “12”
Anterior ratio = Sum mandibular “6” X 100
Sum maxillary “6”
Statistical analysis was done using SPSS program
with t-test. A p level of more than 0.05 was regarded as
statistically non-significant (NS) while figures less than
0.05 were considered as significant (*).
Tooth size discrepancy of the permanent dentition in Class II div. 1 malocclusion… ___________Al-Janabi, Saloom, Al-Taai
RESULTS AND DISCUSSION
Table 1 and2 show that in both groups male crown
measurements were slightly larger and shows higher
variability than the females but follow the same
distribution pattern. Although the difference was not
significant in some of the measurements which agrees
with most of the previous studies.2,10,11
The exact reason behind this difference is not well
understood. However sex-linked inheritance and sexhormonal influence were suggested,13 other suggested
that in adults dimensions of the skeletal component of
the face and jaws could be one of the reasons why large
teeth seem to be related to males than females.10
This study shows that there is a significant
difference in most of the mesiodistal width of the teeth
between group I (crowding) and group II (spacing) with
greater mean values for the first group as shown in table
3, which agrees with most of the previous studies,2,5,6
this larger mesiodistal width in this group (crowding)
may be due to the inheritance of mesiodistal diameter
and dental occlusion where the action of many genes
together with environmental factors will give the final
result (phenotype) of the dental trait according to
polygenic system.7
In crowding group overall ratio was found to be
92.01% while in spacing group it was 91.44%, in
comparison with a previous study by Saleem 11 which
was 91.8% which is less than the crowding group and
more the spacing group this is logical because the
sample in the last study was Cl. II div.1 malocclusion
with no crowding or spacing.
On the other hand anterior ratio were 79.57%,
79.84% in crowding and spacing group respectively,
which were more than that found by Saleem 11 (78.3%).
On the other hand there was no significant
difference between both groups when Bolton ratio was
used regarding both anterior and posterior ratios as
shown in table 4 which agrees with other studies.10,12
Table 1: Comparison of males and females in crowding group (N=15, S.D.=28).
Males
Females
t
p
Mean S.D. Mean S.D.
9.033 0.705 8.933 0.677 0.396 0.695
R
U1
9.053 0.725 8.933 0.697 0.462 0.648
L
6.993 0.274 7.033 0.695 -0.207 0.837
R
U2
6.987 0.345 6.973 0.641 0.074 0.941
L
8.12
0.42
7.907 0.539 1.207 0.237
R
U3
8.04
0.422 7.867
0.51 1.012 0.320
L
7.513 0.203 7.087 0.455 3.311 0.003**
R
U4
7.487 0.281 7.127 0.421 2.755 0.010*
L
7.227
0.39
6.733 0.417 3.351 0.002**
R
U5
7.147 0.435 6.793 0.385 2.360 0.025*
L
11.107 0.464 10.427 0.671 3.228 0.003**
R
U6
11.027 0.486 10.48
0.63 2.663 0.013*
L
5.607
0.39
5.707 0.461 -0.641 0.526
R
L1
5.633
0.35
5.74
0.504 -0.675 0.505
L
6.313 0.276
6.22
0.582 0.559 0.580
R
L2
6.240 0.292 6.253 0.559 -0.080 0.937
L
7.2
0.272 6.987 0.417 1.657 0.109
R
L3
7.32
0.253 7.013 0.883 1.294 0.206
L
7.44
0.222 7.207 0.515 1.609 0.119
R
L4
7.573 0.242 7.213 0.496 2.526 0.017*
L
7.400 0.306 7.227 0.419 1.291 0.207
R
L5
7.433 0.265
7.28
0.461 1.114 0.275
L
11.5
0.387 11.187 0.77 1.407 0.171
R
L6
11.460 0.387 11.187 0.793 1.198 0.241
L
U=upper , L= lower, * significant (p<0.05), ** highy significant (p<0.01)
Tooth
side
23
24 ____________________________________________________________________________________ Iraqi Orthod J 1(2) 2005
REFERENCES
1. Bolton WA. Disharmony in tooth size and its relation to
the analysis and treatment of malocclusion. Angle Orthod
1958; 28: 113-30.
2. Santoro M, Ayoub ME, Pardi VA, Cangialosit J.
Mesiodistal crown dimensions and tooth size discrepancy
of the permanent dentition of Dominican Americans.
Angle Orthod 2000; 70(4) 303-7.
3. Van Der Linder FP. Theoretical and practical aspects of
crowding in the human dentition. J Am Dent Assoc 1974;
89: 139-53.
4. Bolton WA. The clinical application of tooth- size analysis
Am J Orthod 1962; 48: 504-29.
5. Fastlicht J. Crowding of mandibular incisors. Am J Orthod
1970; 58(2): 156-63.
6. Doris JM, Bernard BW, Kuftinec MM, Stom D. A
biometric study of tooth size and dental crowding. Am J
Orthod 1981; 79: 326-36.
7. Smith RJ, Davidscn WM, Gipe DP: Incisor shape and
incisor crowding: a re-evaluate of the peck and peck ratio.
Am J Orthod 1982; 82: 231-5.
8. Yoshihara T, Masumeto Y, Suzuki J, Sato N, Ojuchi H.
Effect of serial extraction alone on crowding: relation
ships between tooth width, arch length and crowding. Am
J Orthod Dentofac Orthop 1999; 116: 691-6.
9. Novderval K, wisth PJ, Boe OE. Mandibular anterior
crowding in relation to tooth size and cranio-facial
morphology. Scand J Dent Res 1972; 83: 267-73.
10. Forsberg CM. Tooth size, spacing and crowding in
relation to eruption or impaction of 3rd molars. Am J
Orthod Dentofac Orthop 1988; 94(1): 57-62.
11. Saleem AE. Permanent tooth size ratio assessment for a
sample of Iraqi patients aged 14-25 year with different
malocclusion type. Thesis, University of Baghdad, 2003.
12. Bernabe E, Biostat C, Villanueva KM, Mir CR. Tooth
width ratios in crowded and non-crowded dentition. Angle
Orthod; 74(6): 763-6.
13. Garn SM, Lewis AB, Kerewsky RS. X-linked inheritance
of tooth size . J Dent Res 1965; 44: 439-41.
Tables 2: Comparison of males and females in spacing group (N=15, S.D.=28).
Males
Females
t
p
Mean S.D. Mean S.D.
8.700 0.442 8.427 0.477 1.626 0.115
R
U1
8.713 0.417
8.5
0.475 1.305 0.202
L
6.953 0.527
6.42
0.304 3.393 0.002**
R
U2
6.927 0.415 6.407 0.308 3.897 0.001**
L
8.08
0.389 7.333 0.438 4.939 0.000**
R
U3
8.013
0.35
7.287 0.452 4.919 0.000**
L
7.087 0.183 6.927 0.314 1.705 0.099
R
U4
7.093 0.225 6.907 0.279 2.010 0.054
L
7.193 0.259
6.8
0.225 4.436 0.000**
R
U5
7.173 0.244
6.86
0.228 3.630 0.001**
L
10.613 0.367 10.173 0.236 3.906 0.001**
R
U6
10.607 0.35 10.167 0.281 3.797 0.001**
L
5.660 0.301 5.307 0.350 2.962 0.006**
R
L1
5.640 0.309 5.313 0.331 2.797 0.009**
L
6.193 0.432 5.907 0.356 1.979 0.058
R
L2
6.180 0.379 5.907 0.336 2.088 0.046*
L
6.987 0.329 6.653 0.234 3.204 0.003**
R
L3
6.987 0.424 6.533 0.261 3.532 0.001**
L
7.147 0.263 6.907 0.295 2.352 0.026*
R
L4
7.133 0.249 6.893 0.269 2.536 0.017*
L
7.180 0.353 7.093 0.371 0.658 0.516
R
L5
7.173 0.359
7.12
0.339 0.416 0.681
L
10.83 0.489 10.693 1.26 0.393 0.698
R
L6
11.120 0.499 10.62 0.310 3.296 0.003**
L
U=upper , L= lower, * significant (p<0.05), ** highy significant (p<0.01)
Tooth
side
Tooth size discrepancy of the permanent dentition in Class II div. 1 malocclusion… ___________Al-Janabi, Saloom, Al-Taai
Table 3: Comparison of the left and right sides between males and females (N=30, S.D.=58).
Spacing
Crowding
t
p
Mean
S.D.
Mean S.D.
8. 563 0. 472 8. 983 0.681 2.78 0.008**
R
U1
8.607 0.453 8.993 0.701 2.54 0.014*
L
6.687 0.502 7.013 0.520 2.48 0.016*
R
U2
6.667 0.446 6.980 0.506 2.54 0.014*
L
7.707 0.556 8.013 0.487 2.27 0.027*
R
U3
7.650 0.543 7.953 0.468 2.32 0.024*
L
7.007 0.265 7.300 0.409 3.30 0.002**
R
U4
7.00
0.267 7.307 0.396 3.52 0.001**
L
6.997 0.311 6.980 0.469 0.16 0.870
R
U5
7.017 0.282 6.970 0.442 0.49 0.630
L
10.393 0.377 10.767 0.664 2.68 0.010**
R
U6
10.387 0.384 10.753 0.619 2.76 0.008**
L
5.483 0.368 5.657 0.422 1.70 0.096*
R
L1
5.477 0.356 5.687 0.430 2.06 0.044*
L
6.050 0.415 6.267 0.450 1.94 0.057*
R
L2
6.043 0.378 6.247 0.438 1.42 0.060
L
6.817 0.326 7.093 0.363 3.11 0.003**
R
L3
6.760 0.416 7.167 0.657 2.86 0.006**
L
7.027 0.300 7.323 0.407 3.21 0.002**
R
L4
7.013 0.283 7.393 0.425 4.08 0.000**
L
7.137 0.359 7.313 0.371 1.87 0.066
R
L5
7.147 0.344 7.357 0.378 2.25 0.028*
L
10.760 0.440 11.343 0.620 2.84 0.007**
R
L6
10.870 0.481 11.323 0.29 3.14 0.003**
L
U=upper , L= lower, * significant (p<0.05), ** highy significant (p<0.01)
Tooth
side
Table 4: Comparison of overall and anterior ratios between crowding and spacing (N=30, S.D.=58).
Tooth ratio
Overall ratio
Anterior ratio
Spacing
Mean S.D.
91.44 2.58
79.84 3.12
Crowding
Mean S.D.
92.01 2.13
79.57 2.67
t
p
0.94
0.35
0.35
0.73
25