Case• 50. Missing upper lateral incisors
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?
The patient does not wish to have gaps between his upper front teeth.
History of complaint
His 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.
The patient is fit and well.
The patient’s mother had a number of teeth missing. They had been replaced with a partial denture at an early age.
The 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 masticatory muscle tenderness.
The 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?
Developmentally absent, possibly associated with cleft lip or palate or other craniofacial syndrome
|Failure to erupt||
Dilaceration and/or displacement as a result of trauma
Scar tissue preventing eruption
Supernumerary tooth preventing eruption
Insufficient space as a result of crowding
Pathological lesion (e.g. cyst or odontogenic tumour) preventing eruption
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% 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.