Timing of human mandibular third molar formation

Background: Population differences in tooth formation using radiographs can be determined if the entire developmental sequence of a single tooth is studied. The only developing tooth visible radiographically from initiation to root completion is the third molar or wisdom tooth. Aim: The timing of mandibular third molar formation was documented for two groups of children in England and two in South Africa. Subjects and methods: Panoramic radiographs of White and Bangladeshi children from London and Black African and Cape Coloured children from South Africa were examined (age 5-24). Mean age of entering third molar stages (crypt appearance to root completion) was calculated using logistic regression and compared between sex and group using a t-test. Results: Average age of third molar stages was significantly (p < 0.001) later in three groups for almost all stages of the third molar compared to Black children. The average age of entering initial mineralization ranged from 7.97 to 9.74 years while average age of apex closed was 19.27-20.88. Conclusion: These results show for the first time a significant difference in the timing of maturation of the mandibular third molar between groups with South African Black children being earlier than other groups.