30 years of the ABFO study: Reproduction in a Brazilian sample.

The ABFO study on third molar development is a benchmark in the scientific literature of dental age estimation. In its 30th anniversary, the study has been reproduced in the present external validation. Standardized comparative outcomes were obtained and discussed across studies. The sample consisted of 1.087 panoramic radiographs of Brazilian females (n=542, 49.87%) and males (n=545, 50.13%) between 14 and 22.9 years. All available third molars were classified into developmental stages following Mincer's adaptation of Demirjian's system (8 sequential stages, from A to H). The mean chronological age of individuals within each stage was assessed. The probability of an individual being ≥ 18 years was calculated for each third molar, sex and stage. Maxillary and mandibular third molars showed a similar development with an agreement between stages of about 90%. In general, males developed 0.5 years (6 months) earlier than females. The probability of being an adult increased considerably when at least one third molar is in stage G. Maxillary third molars had higher coefficients of determination (right: 0.704; left: 0.702), showing that statistical models with these teeth could explain better the age estimation outcomes. The reproducibility of the ABFO study on third molar development led to reference tables and probability measures for the studied Brazilian population.