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D E N T I S T RY
The Orthodontic Restorative
Management of the Peg-lateral
DAN COUNIHAN
Abstract: There are usually two orthodontic options in dealing with the peg-lateral. First,
the lateral incisor can be extracted and the resultant space closed. However, this will often
give a narrow unaesthetic smile. The canine is too yellow and the gingival margin is too
high. The second, preferred, option is often to open the space mesial and distal to the peglateral and create a proper space for a normal-sized lateral incisor. The restorative dentist has
to build up the peg-lateral to simulate a normal-sized lateral incisor.
Dent Update 2000; 27: 250-256
Clinical Relevance: Patients are often concerned about the poor aesthetics of the peglateral. Clinicians should be aware of the management of this problem.
peg-shaped maxillary lateral incisor
is an anomaly of tooth
development characterized by an
alteration in coronal morphology.
Typically, the teeth have a reduced
mesial–distal diameter with the
proximal surfaces converging markedly
in the incisal dimension. The term is
generally applied to those lateral
incisors in which only the middle lobe
calcifies during development.
A
INCIDENCE
A number of studies have discussed the
incidence of peg-shaped maxillary lateral
incisors. Meskin and Gorlin1 reported
that 1.78% of a sample of over 8000
American students demonstrated either
peg-shaped or missing maxillary lateral
incisors, with a higher frequency in
females and a predominance of left-sided
occurrence. Clayton2 found an incidence
of 0.3% in American subjects, while
Dan Counihan, BDS, FDS, FFD, MOrth,
DDOrth, Specialist Or thodontic Practice,Tralee,
Co. Kerry, Ireland.
250
Thilander and Myrberg3 discovered that
0.6% of Swedish schoolchildren had the
anomaly. Al-Emran, investigating
developmental malformations in 500
Saudi Arabian schoolchildren, reported
an incidence of 4%.4
The different results obtained may
reflect differences in the manner in
which the individual studies were
conducted. However, if one accepts the
genetic basis for peg-shaped lateral
incisor anomaly, then the variation of
the results could reflect differences in
the gene pools of the different
population groups.
anomaly: Grahnén7 claimed that pegshaped incisors may be a modified
manifestation of the genotype that
causes hypodontia. Witkop8 proposed
that small, peg-shaped or missing
maxillary lateral incisors are inherited in
an autosomal dominant fashion and
Alvesalo and Portin suggest that missing
and peg-shaping of upper lateral incisors
are different expressions of one
dominant autosomal gene, the
penetrance of which is 72%.6
ASSOCIATED FACTORS
The peg-shaped lateral incisor is one of a
variety of dental abnormalities associated
with hypodontia. A controlled study of
the association of various dental
anomalies with the occurrence of
hypodontia in the permanent dentition
reported that peg-shaped maxillary lateral
incisors occurred in 8.9% of the
hypodontia group, whereas no patient
with this trait was detected in the control
group.9 The researchers concluded that
AETIOLOGY
In general, abnormalities in tooth size
and shape result from disturbances
during the morphodifferentiation stage
of development, perhaps with some
carryover from the histodifferentiation
stage.5
The aetiology of the development of
peg-shaped laterals is probably such that
they have only one (medial) lobe instead
of three.6
A genetic basis has been suggested for
the aetiology of the peg-shaped
Figure 1. Case 1: Poor dental aesthetics.
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O R T H O D O N T I C S
Figure 2. Case 1: Orthopantomogram showing radiolucent area6/.
there was a significant association
between hypodontia and certain dental
anomalies including peg-shaped incisors.
Peg-shaped laterals have also been
Figure 3. Case 1: Crowded lower arch.
observed in patients with cleft lip and
palate. The cleft side lateral incisor is
frequently peg-shaped.10
It is recognized that there is an
association between the form of the
permanent lateral incisor and the
likelihood of ectopic eruption of the
canine. Where the lateral incisor is
small or absent, the probability of a
palatal path of eruption is greatly
increased.11 Peck et al.12 investigated
the prevalence of peg-shaped maxillary
lateral incisors in a sample of white
North American orthodontic patients
with palatal displacement of one or
both maxillary canine teeth. They
reported a ten-fold elevation in the
expression of the peg-shaped anomaly
in the palatally displaced canine (PDC)
sample.
past, peg-shaped lateral incisors were
the tooth of choice for extraction as part
of the orthodontic treatment plan for
crowded mouths. However, with recent
advances in restorative materials, a
number of options are now available to
alter the morphology of such teeth –
including direct composite build-ups,
indirect composite resin veneers,
porcelain veneers and resin-bonded
porcelain crowns. As a result the
extraction of peg-shaped lateral incisors
as part of the orthodontic treatment plan
is less frequently indicated than
previously.
Diminutive teeth may be modified
before, during, or immediately after,
orthodontic tooth movement.15 A pretreatment set-up that simulates the
desired tooth position and the proposed
Figure 6. Case 1: Anterior occlusion lower
incisors influencing arrangment of upper incisors.
TREATMENT OPTIONS
Figure 4. Case 1: Palatal view.
Figure 5. Case 1: Right buccal segment
occlusion.
Dental Update – June 2000
Peg-shaped maxillary lateral incisors
have been listed among the conditions
that can lead to a relative mandibular
excess which can be verified by a
Bolton analysis.13
Miller et al. proposed two treatment
options for such cases:14
● extraction of the diminutive teeth,
moving canines mesially into the
lateral incisor position and reshaping them to simulate lateral
incisors;
● recreating the space and increasing
the size of the peg-shaped laterals.
There can be no doubt that, in the
Figure 7. Case 1: Left buccal segment occlusion
crossbite /6.
Figure 8. Case 1: Upper fixed appliance in
place.
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O R T H O D O N T I C S
restorations is a valuable adjunct to
treatment planning in these cases.13
RESTORATIVE TECHNIQUES
Direct Composite Build-ups
Acid-etch-retained composite is
Figure 9. Case 1: 2/2 have been built up with
composite.
Figure 10. Case 1: Final anterior alignment.
Figure 11. Case 1: Final right buccal segment
occlusion.
Figure 12. Case 1: Final left buccal segment
occlusion.
252
increasingly being used as a reversible
addition to teeth. This method
provides a quick and easy means of
modifying the morphology of
diminutive teeth.16 The earlier
chemically cured composite materials
did, however, have the disadvantages
of poor abrasion resistance and a
tendency to stain, as well as short
working times. The newer light-cured
hybrid and microfilled composite
materials have increased wear
resistance and command set, enabling
incremental build-ups.
As the position of the gingival
margin is not considered to be stable
until 16 years of age, this technique can
be used as an interim restoration to be
followed by a more permanent
restoration such as porcelain veneers or
resin-bonded porcelain crowns.
A major advantage of this technique
is that it can be used without any
preparation of the enamel (other than
acid-etching), so that it is almost
entirely reversible.17 In the case of pegshaped laterals, the composite can be
tapered down to a knife-edge finish
cervically, leaving a cleansable margin
and thus avoiding tooth preparation at
an early age.
Indirect Composite Veneers
The use of indirect laboratoryprocessed composite veneers in the
management of unsightly anterior teeth
in young adolescent patients was
described by Heymann.18 These
restorations are fabricated using a
microfilled laboratory composite,
which is subjected to a secondary or
super curing cycle involving
combinations of light, heat and
pressure. As a result of the more
aggressive curing conditions, the
materials display superior physical
properties compared with their direct
light-cured counterparts.19
It has been pointed out that indirect
fabrication carries the advantages of
less polymerization shrinkage at the
time of placement and enables the
development of restorations with
correct anatomical contour and
acceptable marginal adaptation.20 These
Figure 13. Case 1: Palatal view with bonded
retainer 1/1.
Figure 14. Case 1: Final lower arch.
restorations also tend to withstand the
rigours of an adolescent’s oral
environment somewhat better than
direct-composite veneers; indirect
rather than direct composite veneers
may be indicated where the provision
of porcelain veneers should be delayed.
When reviewing the 2-year clinical
performance of indirect composite
veneers, Heymann18 noted that the
surface glaze had been lost and that the
restorations were prone to chipping and
brittle fracture when subjected to
excessive functional or biting force.
The clinical technique described by
Figure 15. Case 1: Facial appearance.
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O R T H O D O N T I C S
Resin-Bonded Porcelain
Crowns
Figure 16. Case 2: Irregular teeth, pegshaped lateral incisors.
Heymann also has the disadvantage of
requiring tooth preparation, which is
best avoided in younger patients.
Jordan21 also noted that, compared to
porcelain veneers, the indirect
composite veneers lacked the superior
enamel-like reflectivity of fused
Figure 17. Case 2: Right buccal segment
occlusion with crossbite.
porcelain surfaces.
These findings indicate that indirect
composite veneers may have a role as
interim restorations but should be
avoided in situations where they
would be subjected to high occlusal
forces.
Acrylic Laminate Veneers
Figure 18. Case 2: Fixed appliance opening
space for veneers.
Acrylic laminate veneers, whether
prefabricated or custom-made, can be
bonded to etched enamel using a
composite resin cement. However, this
technique suffers from the
disadvantages of poor bonding
between the acrylic and composite
cement and poor abrasion resistance
of the acrylic.
Porcelain Veneers
Figure 19. Case 2: 2/ ready for veneer.
Figure 20. Case 2: Veneers fitted 2/2.
254
Porcelain and castable glass-ceramic
veneers can be bonded to teeth by use
of a resin-based cement, using a
combination of techniques and
mechanisms. This technique was first
introduced by Horn22 as a means of
modifying the appearance and
morphology of anterior teeth with
minimal tooth preparation. These
restorations have proved more durable
than composite or acrylic alternatives.
The advantages include excellent
biocompatability, good abrasion
resistance, good bonding because of
both mechanical and chemical factors
and excellent aesthetics. The
limitations include laboratory costs,
fragility during cementation and
difficulty in reglazing if adjustments
are made.
The resin-bonded porcelain crown has
been defined as a porcelain veneer
which has been extended
circumferentially to involve a
substantial proportion of the lingual/
palatal aspect of the tooth.23 The crown
is retained by means of an etched and
silanated fitting surface and composite
resin luting agent via acid-etched
enamel or appropriately treated dentine.
The modification of diminutive teeth
such as peg-shaped lateral incisors was
listed among the indications for use of
this type of restoration.23
Apart from the potential for excellent
aesthetics, this type of restoration has
several advantages when restoring peglateral incisors. As the diminutive
tapering morphology of peg-laterals
conforms closely to the desired crown
preparation, the incorporation of a
chamfer-type margin and removal of
sharp edges may be the only
preparation that is required. This
avoids endangering the pulp and
preserves enamel, which can be etched
to provide micromechanical retention
for the resin cement.
Orthodontic alignment of the anterior
teeth can redistribute the space to
facilitate the placement of
appropriately sized crowns.
Owing to the brittle nature of these
restorations, care is required to avoid
fracture during try-in and cementation
procedures. Laboratory support is
required for their fabrication and
considerable skill is required during the
finishing procedures, especially
interproximally.
Figure 21. Case 3: Anterior view showing peglateral.
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O R T H O D O N T I C S
Figure 22. Case 3: Orthopantomogram showing palatally impacted3/.
CASE REPORTS
Three case reports are shown to
illustrate the combined management of
this problem.
Case 1
This 25-year-old woman disliked the
arrangement of her upper and lower
anterior teeth (Figures 1–7). She had a
midline diastema; 6/ had a large
restoration and an apical area (Figure
2). She had considerable lower incisor
crowding. Her upper left first molar
had been extracted in the past, and the
lower left first molar was in crossbite.
The 6/5 were extracted and upper and
lower fixed appliances were placed.
Space was opened mesial and distal to
2/2 (Figure 8) and composite resin
build-ups placed on these teeth (Figure
9). All the remaining spaces were then
closed. The upper central incisors were
aesthetically recontoured (Figure 10)
and a bonded retainer placed palatal to
1/1 to prevent reopening of the central
diastema. A satisfactory buccal segment
occlusion was achieved (Figures 10–
12), with the anticipation that this would
maintain the stability of the corrected
malocclusion.
The patient was happy with the dental
and facial aesthetics (Figures 13–15).
examination it was noted that upper 2/2
were peg-shaped (Figures 16 and 17).
A treatment plan involving the
extraction of four premolars followed
by upper and lower fixed appliances
was recommended. Space was opened
mesial and distal to 2/2. The space was
monitored throughout treatment (Figure
18). Following orthodontic treatment
Essix retainers were fitted to maintain
the space (Figure 19). The restorative
dentist fitted porcelain veneers to 2/2
(Figure 20).
upper left canine was erupted, rotated
and slightly palatal; her upper right
canine was unerupted and palatal to the
upper right central incisor. An
orthopantomogram also revealed third
molars (Figure 22). It was felt that the
patient would not accommodate 32
permanent teeth.
In order to provide space for distal
movement, it was initially decided to
extract the upper second molars before
treatment (the lower third molars would
need to be removed at a later date).
Upper appliances supported by
headgear were used to distalize the
upper buccal segments and gain space
to align the canines and open space
mesial and distal to 2/2.
2/2 were built up mesially and
distally with composite (Figures 23 and
24). Figure 25 shows the composite
build-ups 6 years 9 months after the
initial build-ups.
CONCLUSION
Patients are now aware and educated in
the area of dental and facial aesthetics
Case 3
A14-year-old girl was concerned about
the appearance of her anterior teeth and
that her upper right canine had not
erupted. Her overjet and overbite were
increased (Figure 21) and she had a
Class II buccal segment occlusion. Her
Figure 23. Case 3: Post-treatment anterior
occlusion with composite build ups on 2/2.
Case 2
An adult patient was referred by her
dentist complaining of irregularity and
overcrowding (Figure 16). On
Dental Update – June 2000
Figure 24. Case 3: Post-treatment orthopantomogram.
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O R T H O D O N T I C S
Figure 25. Case 3: Anterior occlusion six years
post-treatment.
timing is very important. Following
treatment, the patient should be
reviewed regularly by the restorative
dentist. By the mid teens, it may be
advisable to renew the composite buildup to improve colour, which will
improve the patient’s self-esteem and
psychological well-being. Once tooth
development is complete, a more
permanent restoration (veneer, crown)
can be placed.
10.
11.
12.
13.
(most fashion magazines usually
feature a beautiful broad full smile on
their cover). We now prefer a full
dentition with good lip support, and lip
eversion with a showing of vermilion is
favoured. For these reasons dentists
will usually try to preserve the
dentition – and especially the upper six
anterior teeth. A peg-lateral is often
aesthetically unacceptable.
Nowadays, the extraction of this
tooth will involve a combined approach
by the orthodontist and restorative
dentist to achieve optimum results. In
the young child a composite build-up is
probably the best restoration. However,
there are problems with long-term
colour stability and a veneer or crown
may be the preferred option for the
older patient. The problem of the peglateral is complicated and needs
attention over many years.
The patient should be referred early,
as soon as the problem is recognized,
to the orthodontist: the orthodontist
may wish to gain the extra space
needed to correct the problem of
undersized lateral incisors by using
leeway space or distal movement, so
ABSTRACT
CAN FIXATIVES SOLVE YOUR
DENTURE PROBLEMS? Use of
denture adhesives. A.J. Coates. Journal
of Dentistry 2000; 28: 137-140.
Dental research often seems to focus on
the esoteric and be unrelated to the ‘real
world’ of general dental practice. This
author discovered that there was
virtually no literature relating to the use
of denture fixatives, and set out to
256
A CKNOWLEDGEMENT
My thanks to Dr Tony Trant, Dr Denis Reen and Dr
Jim Gleeson for carrying out the restorative
work for the patients discussed in this pa per.
14.
15.
RE F E R E N C E S
1.
2.
3.
4.
5.
6.
7.
8.
9.
Meskin LH, Gorlin RJ. Agenesis and peg-shaped
permanent maxillar y lateral incisors. J Dent Res
1963; 42: 1476–1479.
Clayton JM. Congenital dental abnormalities
occurring in 3,557 children. J Dent Child 1956;
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Thilander B, Myrberg N. The prevalence of
malocclusions in Swedish school children.
Scand J Dent Res 1973; 81: 12–21.
Al-Emran S. Prevalence of hypodontia and
developmental malformations of permanent
teeth in Saudi Arabian school children. Br J
Orthodont 1990; 17: 115–118.
Proffit WR, Fields HW. In: Contemporary
Orthodontics. Mosby, 1993; p.112.
Alvesalo L, Portin P.The inheritance pattern of
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Grahnén H. Hypodontia in the permanent
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Witkop CJ. Agenesis of succedaneous teeth: an
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Lai PY, Seow WK. A controlled study of the
remedy this situation.
Identifying such topics often tests the
vocational trainee but, by using a simple
questionnaire, it is not difficult to obtain
such useful information.
The totally edentulous respondents
were approximately two-thirds female,
one-third male, and two-thirds of them
were over 60 years of age. Most had
worn dentures for at least 10 years, and
18% for over 20 years.
Interestingly, only 6.9% of the
respondents used denture fixative
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17.
18.
19.
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21.
22.
23.
association of various dental anomalies with
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regularly. Of the total response, only
32.9% had ever tried it, the remainder
presumably expressing satisfaction with
the fit of their dentures. I say presumably
because 20.5% of the respondents had
never heard of denture fixative. The
author may have discovered a previously
unrealized false assumption on behalf of
dental practitioners, whose denture
practice may benefit by a little patient
information.
Peter Carrotte
Glasgow Dental School
Dental Update – June 2000
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