Third molar maturity index (I3M) assessment according to different geographical zones: a large multi-ethnic study sample

Identifcation of living undocumented individuals highlights the need for accurate, precise, and reproducible age estimation methods, especially in those cases involving minors. However, when their country of origin is unknown, or it can be only roughly estimated, it is extremely difcult to apply assessment policies, procedures, and practices that are accurate and childsensitive. The main aim of this research is to optimize the correct classifcation of adults and minors by establishing new cut-of values for four diferent continents (Africa, America, Asia, and Europe). For this purpose, a vast sample of 10,701 orthopantomographs (OPTs) from four continents was evaluated. For determination and subsequent validation of the new third molar maturity index (I3M) cut-of values by world regions, a cross-validation by holdout method was used and contingency tables (confusion matrices) were generated. The lower third molar maturity indexes, from both left and right side (I3ML and I3MR) and the combination of both sides (I3ML_I3MR) were calculated. The new cut-of values, that aim to diferentiate between a minor and an adult, with more than 74.00% accuracy for all populations were as follows (I3ML; I3MR; I3ML_I3MR, respectively): Africa=(0.10; 0.10; 0.10), America=(0.10; 0.09; 0.09), Asia=(0.15; 0.17; 0.14), and Europe=(0.09; 0.09; 0.09). The higher sensitivity (Se) was detected for the I3ML for male African people (91%) and the higher specifcity (Sp) of all the parameters (I3ML; I3MR; I3ML_I3MR) for Europeans both male and female (>91%). The original cut-of value (0.08) is still useful, especially in discriminating individuals younger than 18 years old which is the goal of the forensic methods used for justice