Validation of Cameriere's third molar maturity index alone and in combination with apical maturity of permanent mandibular second molar for indicating legal age of 14 years in a sample of South Indian children

The aims of the present study were to validate the discriminatory potential of Cameriere’s third molar maturity index (I3M) cut-off value of I3M < 1.1 and whether closed apices of permanent second mandibular molar (I2M = 0.0) and I3M < 1.1 indicate the legal age of 14 years and older. A digital orthopantomograms of 804 healthy South Indian children, aged between 10 and 18 years, were collected retrospectively, and mineralization of the third and second left mandibular molars was analyzed by Cameriere’s method. The proportion of accurately classified (Ac) individuals using the cut-off value of I3M < 1.1 was 79.4% for males, with Bayes post-test probability (Bayes PTP) of 68.8%. For females, Ac was 79.9% and Bayes PTP was 70.9%. The sensitivity was 94.8% and 98.2% for males and females, and the specificity was 58.7% and 62.8%, respectively. The combination of both variables, I3M < 1.1 and I2M = 0.0, increased the Ac to 87.2% and 94.4% in males and females, the specificity to 98.6% and 99.2%, and Bayes PTP to 98.2% and 94.4%, respectively. In conclusion, the suggested cut-off value of I3M < 1.1 is of moderate accuracy in discriminating individuals between 14 years or older from those under 14 years in the studied population. A combination of both variables, I2M = 0.0 and I3M < 1.1, the discriminating test achieves an excellent specificity and Bayes PTP, which is mandatory for the forensic and medicolegal purposes.