Legal age determined by a new threshold value of third molar maturity index in subjects with impacted mandibular third molars: An orthopantomographic study in south Indian adolescents.

Third molars are one of the few biological markers available for age estimation in juveniles, especially for the estimation of the 18-year-age threshold. Literature has indicated that impaction has an influence on the development of third molars, which could possibly result in age misclassifications. The present study is intended to identify an alternative cut-off value of the third molar maturity index (I3M) in impacted mandibular third molars and also to evaluate its applicability in estimating the major (≥ 18 years)/minor (< 18 years) status. A total of 1330 digital orthopantomograms (OPGs) of 665 male and 665 female south Indian adolescents aged from 15 to 22 years were collected and assessed. Eight hundred forty OPGs (63.1%) represented test sample, and 490 OPGs (36.9%) represented validation sample. I3M was measured for the total sample. Logistic regression, receiver operating characteristic (ROC) curve analysis, and Youden's index were used to test the performance of the method in the test sample. An alternative cut-off value of I3M < 0.17 was established for the highest value of the Youden's index of 0.598 for both sexes. When tested in validation sample, it has resulted in sensitivity and specificity values of 0.91 (95% CI; 0.86-0.95) and 0.90 (95% CI; 0.78-0.91) in males and 0.86 (95% CI; 0.80-0.92) and 0.90 (95% CI; 0.83-0.95) in females. In conclusion, cut-off value of I3M < 0.17 could accurately discriminate adults from minors with impacted mandibular third molars. However, more work is needed to be done among a more diverse sample to confirm these findings.

A test to study the influence of impaction on mandibular third molar development and forensic age estimation in a sample of south Indian children and young adults.

It has been argued that the impaction of the third molars could result in delayed maturation, which, in turn, could affect age estimations in criminal proceedings. In view of this, the present study was undertaken to determine whether the impaction status could delay the chronological process of third molar mineralization in a sample of south Indian children and young adults. The orthopantomograms (OPGs) of 915 children and young adults of south Indian origin aged between 15 and 22 years were evaluated. Mineralisation stage and impaction status were determined for all lower third molars. Descriptive statistics were performed at stages D to H of Demirjian staging system. The results of independent t-test show that the impaction resulted in statistically significant slower mineralization in impacted lower third molars at stages D to F in both sexes. It was ascertained that the mean ages with the impacted lower third molars at stage G were 0.98-1.38 years higher in males and 0.50-0.80 years higher in females than those with non-impacted lower third molars. For stage H, the mean ages were 0.14-0.21 years higher in males and 0.25-0.44 years higher in females. The probabilities of being 18 years and above is higher for non-impacted lower third molars at stages G and H than those with impacted ones. It is concluded that the impaction could result in delayed maturation in the lower third molars of the studied sample. Further studies are warranted in a more diverse sample.