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Case • 50
Missing upperlateral incisors
SUMMARY A 15-year-old boy presents to you in general dental
practice requesting closure of the spaces between
his upper front teeth. What is the cause and how can
a better appearance be achieved?
Medical historyThe patient is fit and well.
Family historyThe patient’s mother had a number of teeth missing. They
had been replaced with a partial denture at an early age.
Examination
Extraoral examinationThe patient has a skeletal class I appearance without facial
asymmetry. There is a slight deviation of the mandible to
the patient’s left-hand side on opening, but no limitation of
opening, temporomandibular joint clicks or crepitus or mas-
ticatory muscle tenderness.
Intraoral examinationThe patient’s soft tissues are healthy and his oral hygiene is
good, with no calculus deposits, gingival inflammation or bleeding on probing. The teeth appear sound, with the
exception of a buccal amalgam restoration in the lower left
first molar.
Study models taken for treatment planning are shown in
Figure 50.1.
� What features relevant to treatment do the study models
show?
Both upper lateral incisors are absent. From the front the
upper central incisors are upright and separated by a large
midline diastema. There is a mild class III incisor relationship,
with a normal overjet but a reduced and complete overbite. The upper canines are mesially inclined and mesiolabially
rotated, that on the left being more prominent. The lower
right canine is labially placed, slightly distally inclined and in
crossbite with the upper canine. There is mild lower labial
crowding. The posterior teeth are well aligned and the first
molars on the right-hand side are in a class I relationship and
on the left-hand side in a half a unit class II relationship.
� What are the possible causes for the absent lateral incisors?
What is the cause in this case?
Fig. 50.1 Study models taken at presentation.
History
ComplaintThe patient does not wish to have gaps between his upper
front teeth.
History of complaintHis permanent teeth erupted at a normal age with large
spaces between them. The primary predecessors had all
been present and were exfoliated normally. None of the
permanent teeth has been extracted.
In this case the most likely cause for the missing lateral
incisors is genetic absence. Genetic absence of some teeth is
found in 3–7% of the population. The teeth most commonly
missing are, in descending order of frequency, third molars,
maxillary lateral incisors and second premolars. The absence
of maxillary lateral incisors is a hereditary trait in about 1–2%
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of the population. The fact that the patient’s mother wore a
denture to replace missing teeth from an early age suggests a
possible familial aetiology. Trauma or extraction and their
related sequelae are readily excluded by questioning. The
other causes are discussed in Case 5.
Investigations� What investigations are required? Explain why for each.
teeth are present including the unerupted third molars. This
confirms the diagnosis that the upper lateral incisors are
developmentally absent.
Treatment
� What are the main treatment options? What are theiradvantages and disadvantages?
Fig. 50.2 Panoramic radiograph.
In this case all the upper anterior teeth responded to testsof vitality by ethyl chloride and an electric pulp tester.
� The panoramic radiograph is displayed in Figure 50.2. What
does it show?
The dental panoramic radiograph shows that the
upper lateral incisors are missing with no evidence of
supernumerary teeth or other lesions in this region. All other
� The patient’s main concern is his appearance. How would
you demonstrate the possible results to him?
The patient is considering committing himself to a long and
complex treatment so the result of each of the treatment
plans should be assessed with study models and diagnostic
wax-ups. The possibility of the orthodontic treatment can be
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mesiolabially rotated and the orthodontic result is potentially
unstable. Relapse would result in the pontics swinging out
labially. An alternative might appear to be a cantilever design
retained on a central incisor (option B) which has the
advantage of a greater enamel area for bonding. However,
two separate cantilever bridges retained on the central
incisors would also enable the orthodontic result to relapse
and the midline diastema to reappear. Linking the central
incisors together (option C) would prevent this but could
not prevent the canines from relapsing to their originalposition.
A degree of orthodontic retention must be designed into the
prosthesis and only a fixed–fixed bridge extending from
canine to canine is suitable (option D). The potentially
unstable orthodontic result may in itself favour debonding of
one of more of the wings. Regular recall will be essential to
detect this early. If debonding is a repeated problem,
replacement with a conventional bridge may have to
be considered. The need for orthodontic retention is the
main reason that an implant retained solution is not
appropriate.
The final bridge design and appearance are shown in
Figure 50.5. Note how the orthodontic treatment plan must
take into account the occlusal clearance required to cover
the palatal surfaces of the canines.
visualized by cutting the teeth off duplicate study models and
fixing them in an orthodontically achievable position, the
so-called Kessling set-up. Patient and dentist can then see
what might be achieved by each treatment option.
Following discussion, the patient opts for the third treat-ment plan.
� How would you carry out the orthodontic treatment?
The tooth movement demands fixed appliance treatment.
Tooth tilting using a removable appliance would result in a
poor appearance in the midline and produce spaces which
are difficult to fill with a prosthetic replacement. If a
fixed appliance is used the incisors may be more
accurately positioned and derotation of the canines is
possible. The orthodontic result for this patient can be seen
in Figure 50.3.
� How would you now replace the missing lateral incisors?
Prosthetic treatment should be as conservative as possible
because the upper anterior teeth are vital and sound, and the
patient is young. The teeth can be replaced with fixed or
removable prostheses but the treatment of choice would be
a minimum preparation bridge or bridges. Possible designs
are shown in Figure 50.4.
Normally a fixed–fixed design in a minimum preparation
bridge should be avoided. This is because debonding of one
retainer will create an area of stagnation below it and risk
caries. A typical minimum preparation bridge to replace a
lateral incisor would be a cantilever design retained on thecanine or central incisor.
However canine abutments (option A) would have a major
disadvantage in this case. The canines were originally
Fig. 50.3 The final orthodontic result.
a
b
Fig. 50.4 Possible designs for minimum preparation bridge(s).
D
C
B
A
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� What else has been done to improve the appearance of the
final result? Look closely and compare Figure 50.5b with
Figure 50.1.
The lower arch has been treated orthodontically. One lower
incisor has been extracted and the space gained has been
used to align the lower incisors and the lower right canine,
which was in crossbite. This has made a significant
contribution to the final appearance.
Fig. 50.5 The final result.
a
b