Juvenile versus adult: A new approach for age estimation from 3-dimensional analyses of the mandibular third molar apices

Rapidly evolving three-dimensional imaging techniques can be effectively employed in forensic sciences to overcome the limitations of two-dimensional imaging modalities. The aim of the present study was to find a threshold value of 18 years age among Malays to differentiate juvenile verses adults based on three-dimensional image analysis of developing mandibular third molars apices. The study also investigated the correlation between chronological age and the surface area of developing mandibular third molars apices. Malay specific regression equation for age estimation was derived. Seventy three mandibular molars were selected from 73 CBCT images belonging to 37 male and 36 female, ranging in age from 15 to 23 years. Mimics and 3-Matics software were employed to generate 3D image models and quantification of surface area analysis of developing mandibular third molars. The results indicated a strong inverse correlation (r = 0.918, SE = 1.025) between chronological age and the predictor variables. The R-Square (R2) value showed that 84.2% of the variation in age can be explained by surface area of the apices, and status of the root development (open/closed apices). Post hoc analysis indicated that the mean value of apex surface area of 18 years age group was significantly different from the mean values of 15, 16, 17, 22 and 23 years age groups. The results indicated that (based on the 95% confidence interval) if the apex surface area is below 9.25 mm², then it is more likely that the Malay person is 18 years of age or above, irrespective of gender.