Congenitally absent third molars in 12 to 16 year old Singaporean Chinese patients: a retrospective radiographic study.

Third molars have been associated with a host of pathologies and there are risks involved with their surgical removal. They also have the highest incidence of congenital absence of all the permanent teeth. The aim of this study was to determine the prevalence and distribution of congenitally missing third molars in local Chinese patients. The orthopantomographic radiographs of 786 Singaporean Chinese patients aged 12 to 16 years were examined. It was found that 562 (71.5%) of the children had all 4 third molars. Varying degrees of third molar agenesis were noted in the other 224 (28.5%) children. Of these, 43 (5.5%) showed total absence of third molars. There was no significant difference in agenesis between the right and left sides and no sexual predilection was noted. However, more third molars were missing from the maxilla compared to the mandible, the ratio being 3:2.