Mandibular third molar maturation stage as indicator for the legal adult age in an Egyptian sample

Determination of the age of majority is of critical importance in forensic and legal practice. This study aimed to assess the mandibular third molar maturation stage in discriminating adults and minors in an Egyptian population sample using two methods: Cameriere's third molar maturity index (I_3M) and Demirjian's stage of maturation; further, the I_3M cut-off value of < 0.08 for age 18 years and older was tested. The study included 350 digital panoramic radiographs of 14-24 years old participants. The effectiveness of I_3M < 0.08 and Demirjian's stages were assessed using sensitivity, specificity, accuracy, post-test probability, positive likelihood ratio, and negative likelihood ratio. Receiver operating characteristic (ROC) curves were constructed to detect the overall effectiveness of I_3M and Demirjian's stages to determine adults. I_3M < 0.08 showed accuracy, sensitivity, specificity, post-test probability, positive and negative likelihood ratios of 88.65%, 91.74%, 83.67%, 90.6%, 5.62 and 0.10 respectively in males, and 82.76%, 80.16%, 87.04%, 91.03%, 6.18 and 0.23 in females. Stage H showed the best specificity and post-test probability within Demirjian stages; 91.84% and 94.06% in males and 90.74% and 91.84% in females. Both I_3M and Demirjian's stage H of the mandibular third molar were useful indicators for discriminating between Egyptian adults and minors. The cut-off value of I_3M < 0.0625 in males and I_3M < 0.104 in females showed a better discrimination performance than I_3M < 0.08 among Egyptians.