Accuracy of third molar eruption for legal age estimation using the Gambier method in Lebanese subadults

Assessing whether an individual has reached the legal age of 18 is a complex, multifactorial process that requires the application of reliable, standardized, and reproducible methods. Among the various approaches, the assessment of third molar eruption has recently emerged as a useful preliminary tool for estimating whether an individual has reached the age of majority. This study aims to evaluate the accuracy of the Gambier et al. scoring system for legal age estimation based on third molar eruption in a sample of Lebanese subadult individuals. A retrospective analysis was conducted on 537 orthopantomograms (OPGs), comprising 298 males and 239 females, aged between 15 and 24 years. An increase in mean chronological age was observed with the progression of third molar eruption stages (1-3) and phases (A-D) in both sexes. Only in limited cases has a strong relationship been found between phase D and the probability that an individual is 18 years of age or older. In this Lebanese sample, phase D, which corresponds to complete emergence in the occlusal plane, was not always associated with individuals being 18 years or older: the 11.9% of males and females in this phase is above the legal age threshold. This technique may serve only as a preliminary tool for estimating the probable age of alleged minors of Lebanese origin, particularly in the context of migrant populations and child marriage contexts. Its application is recommended in accordance with the minimum age principle, as minimum age thresholds have been established for each stage and phase of third molar eruption. This method, however, ought to be applied only in combination with other internationally validated dental age estimation methods, thereby safeguarding against potential ethical implications associated with legal age assessment.