|SECTION II||EXTRA OR SUPERNUMERARY TEETH|
Supernumerary teeth are teeth that form in excess of the normal number of teeth for each quadrant. [They occur in 0.3% to 3.8% of the population.7] They are found in both permanent and primary dentitions [with 90% of all occurrences in the maxilla].8 Specifically, the most frequent supernumerary specimens are found in one of two locations: maxillary incisor area or maxillary third molar region. One report states that supernumerary teeth occur eight times more often in the maxillary than mandibular regions and twice as frequently in men than in women.9 [Another study of 50 patients from 16 months to 17 years of age found 20% of the supernumerary teeth to be inverted.10 Fourteen percent of these patients had multiple supernumerary teeth, and 80% of the extra teeth were in a lingual position relative to the dental arch.] Supernumerary teeth can vary considerably in size and shape.
The most common location of supernumerary teeth in the permanent dentition is located at the maxillary midline (called a mesiodens). A mesiodens [ME zee o denz] is a small supernumerary tooth that forms between central incisors. It has a cone-shaped crown (Fig. 11-4A and B) and short root. It may be visible in the oral cavity or remain unerupted. If unerupted, a diastema (space) may be present.11 One study of 375 children with mesiodens reports that they are often in an inverted position and rarely erupt into the oral cavity (Fig. 11-4C).9