Testing the maturation and the radiographic visibility of the root pulp of mandibular third molars for predicting 21 years. A digital panoramic radiographic study in emerging adults of south Indian origin.

Prediction of the attainment of legal age thresholds, especially in children and young adults, is a common task in medico-legal practice. In many countries, 21 years has medico-legal importance. In the present study, we assessed and compared the accuracy of the third molar maturity index (I3M) and the stages of radiographic visibility of the root pulp (RPV) in predicting the age threshold of 21 years. A sample of 910 digital panoramic radiographs (455 males and 455 females) of adolescents and young adults aged between 16 and 30 of south Indian origin were evaluated. The authors examined the performance of different I3M cut-off values and RPV stages. I3M cut-off value of 0.02 has resulted in better discrimination with an accuracy of 76.92% and 80.44%, specificity of 48.28% and 56.16% in males and females, a sensitivity of 100%, and post-test probability of 65.9% in both sexes. The accuracy and sensitivity of RPV stage 2 were 84.76% and 84.55%, 78.17%, and 78.97% in males and females, while the specificity and post-test probability were 100% in both sexes. In conclusion, the I3M method resulted in a more significant percentage of false positives and cannot be used to state the attainment of 21 years. However, the presence of RPV stage 2 could say that the subject had already attained the age of 21 years. Further studies are warranted to address the usefulness of these methods.