Late-forming supernumerary teeth.

Supernumerary teeth can occur in both arches, in either the deciduous or the permanent dentition.1-3 The majority are found in the mandibular arch and in male patients, and the premolars are the teeth most commonly affected.4-9 Supernumerary maxillary premolars have a variable morphology, while those in the mandible usually mimic the shape of a normal premolar crown.10,11 Supernumeraries tend to grow more lingually and vertically than normal premolars. The crown of a supernumerary premolar generally forms between the ages of 12 and 14, but root growth can continue until age 23.12 It has been hypothesized that a supernumerary, rather than being an abnormality of a normal dentition, may represent a post-permanent dentition.13,14 Grahnen and Lindahl reported that 3.1% of the patients in their sample had supernumerary teeth, with 18% of these being late-forming supernumeraries in the mandibular premolar region.15 In another study, the incidence of supernumeraries was .29-.64%, with 8-10% of these forming late in the premolar region.16 When the supernumerary develops later than the permanent tooth, the tooth germ can be resorbed or dislocated. A supernumerary can also cause the formation of an odontogenic cyst, and it can displace the adjacent teeth, causing interdental spacing, root resorption, or rotation.17,18 Early detection is important in minimizing these complications. Surgical removal is the treatment of choice, but carries the risk of damaging the adjacent teeth or structures. There is also the possibility of a loss of vitality of adjacent teeth from damage to the vascular lymphatic supply, as well as the risk of paresthesia due to nerve damage. Therefore, it is essential to determine the exact location of the supernumeraries prior to surgery. If the patient shows no adverse effects, it may be advisable simply to follow the supernumerary development radiographically in case intervention is unnecessary. The following three cases are typical examples of late supernumerary formation.ope