Inter-population variation in third molar agenesis and its effect on dental age estimation: Evidence from black and white South Africans

Third molar development is widely used for dental age estimation (DAE) in late adolescence and young adulthood; however, agenesis of one or more third molars can compromise its reliability in forensic practice. The prevalence of third molar agenesis is known to vary across population groups, yet its practical impact on forensic age assessment remains insufficiently explored. This study aimed to assess the prevalence and distribution of third molar agenesis in Black South Africans (BSA) and White South Africans (WSA) and to assess its impact on DAE according to sex, tooth position, and birth cohort. A retrospective analysis was conducted on orthopantomograms (OPGs) from 2536 individuals comprising 1688 BSA and 848 WSA. Third molar agenesis was evaluated by tooth position, sex, population group, and birth cohort. Statistical analyses were performed to identify significant intergroup and intragroup differences. Third molar agenesis was significantly more prevalent in WSA (28.42 %) compared to BSA (6.81 %). The overall prevalence of at least one missing third molar was 14.92 % in males and 13.33 % in females. Agenesis occurred slightly more frequently in the maxillary arch (2.48 %) than in the mandibular arch (1.93 %), with no consistent sex- or side-related differences. Birth cohort analysis demonstrated a declining trend in the prevalence of agenesis over time, potentially reflecting demographic and evolutionary influences. The prevalence of third molar agenesis varies significantly between South African population groups, highlighting the influence of genetic ancestry and population-specific factors on dental development. Sole reliance on third molar assessment for DAE may result in inaccurate age estimation, particularly in multi-ethnic populations. Population-specific reference data for third molar development are essential to improve the accuracy and reliability of forensic dental age estimation. Incorporating such data can reduce misclassification and enhance the validity of medico-legal assessments.