50.Missing Upper Lateral Incisors

7/21/2019 50.Missing Upper Lateral Incisors

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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%



M I S S I N G U P P E R L A T E R A L I N C I S O R S

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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

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50.Missing Upper Lateral Incisors