Agenesis of the Second Premolar in the Mandible
Agenesis of mandibular second premolars affects about 3% of children. Treatment options include extraction, orthodontics, autotransplantation, or implants. The prognosis for retained primary molars is often good, but infraocclusion and root resorption can impact long-term survival.
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This article is based on an original article in Swedish which can be found here
BACKGROUND
Absence of tooth buds (agenesis/aplasia) for one or both second premolars in the mandible occurs in 3-5% of children (1-8). For Scandinavian children, around 3% (1-5). This means that on average, there should be nearly one student in every classroom with this dental anomaly. For children with normal dental development, the diagnosis can be established at 9-10 years of age. In some cases, the buds may not be visible until the child is 11-12 years old, but this is very rare.
In a fairly large proportion of children with agenesis/aplasia, pronounced root resorption and/or infraocclusion of the primary second molars can be observed as early as 9-11 years of age. These primary molars should be removed, and one can expect good mesial migration and space reduction in most children. However, consideration must be given to the type of occlusion; in some cases, tipping of the first permanent molars may occur. Sometimes, for various reasons, the other primary molars remain in place at 12-13 years of age. In such cases, it may be more difficult to decide what to do.
Association with other dental anomalies
Several studies have shown that children with agenesis of the mandibular second premolars often have this combined with other dental anomalies (9-11), e.g.:
- Impacted maxillary canines in ectopic positions
- Ectopic eruption of the maxillary first permanent molars
- Agenesis of the maxillary laterals
- Missing maxillary laterals
Children diagnosed with ectopic eruption of the maxillary first permanent molars at 6-7 years of age can thus be considered at risk for later developing agenesis of the mandibular second premolars.
TREATMENT
There are various treatment options both at 9-10 years of age and later. First, a comprehensive assessment of the patient's maturity and the interest of the patient and parents in treatment must be made. An assessment of the type of occlusion and growth pattern should also be conducted to get an idea of the possibility of good space closure if the other primary molar is extracted.
