Age estimation based on Demirjian's method using third molars in individuals from Southeastern Brazil

This study assessed the applicability of third molar mineralization stage for estimating chronological age in a Southeastern Brazilian population and tested a previously developed age estimation formula from a Northeastern Brazilian population. Digital panoramic radiographs of 1570 individuals aged 7-22 years were analyzed; 1260 radiographs were used to create the new formula, and 310 to test it. Two independent examiners classified the third molars on the radiographs according to Demirjian's developmental stages. Paired t-test compared chronological and estimated ages; Mann-Whitney test assessed sex differences in mineralization stages (α = 0.05). Multiple linear regression was used to develop a new age estimation formula. Chronological age was similar across all four third molars for different developmental stages, with no sex-related significant differences (p > 0.05). The initial appearance of third molar formation (stage A) and root apex closure (stage H) occurred at mean ages of 8.6 and 19.8 years, respectively. A strong correlation (R = 0.925) was found between chronological age and third molar mineralization stages. The previously developed formula significantly overestimated chronological age by approximately one year (p < 0.05). In contrast, the new formula achieved strong performance, explaining 85 % of the variance in the outcome (R² = 0.85), with low prediction errors (MAE = 1.35; RMSE = 1.71), with no significant differences between estimated and chronological age for most age groups (p > 0.05). This study confirms the strong correlation between third molar mineralization stages and chronological age in a Southeastern Brazilian population. It also underscores the need for population-specific models, as the previously developed formula led to overestimation. The new formula provides a more accurate method for age estimation in this subpopulation, supporting its forensic and clinical applicability.