Third molar maturity index (I3M) for assessing age of majority in a black African population in Botswana

Abstract

Assessment of legal age, also known as age of majority, is a controversial issue as there are few body biomarkers or evidence during late adolescence differentiating a subject from being a minor or adult. The third molar was recognized as a suitable site for age examination in late adolescence. We analyzed the development of the left mandibular third molar by the third molar maturity index (I3M) and a specific cut-off value of I3M = 0.08, established by Cameriere et al. in 2008 and used it for discriminating between minors and adult black Africans from Gaborone, Botswana. A final sample of panoramic radiographs (OPTs) of 1294 people (582 males and 712 females) aged between 13 and 23 years was evaluated. The real age decreased as I3M gradually increased. There was no statistically significant difference in the third molar development evaluated using I3M between males and females (p > 0.05) across different I3M classes. Results of 2 × 2 contingency tables for different cut-off values indicated that I3M = 0.08 was useful in discriminating between adults and minors. Precisely, for I3M = 0.08, the values of accuracy or overall fraction of correctly classified were 0.91 in males with a 95 % confidence interval (95 % CI) of 0.88 to 0.93 and 0.92 (95 % CI, 0.90 to 0.93) in females. Values of sensitivity of the test or the proportion of participants being 18 years and older were 0.88 (95 % CI, 0.87 to 0.90) in males and 0.88 (95 % CI, 0.90 to 0.93) in females, while values of specificity or proportion of individuals younger than 18 who have I3M <0.08 were 0.94 (95 % CI, 0.91 to 0.96) in males and 0.96 (95 % CI, 0.94 to 0.98) in females. Positive predictive values of the test, where the participants whose I3M <0.08 were adults, were 0.94 (95 % CI 0.91 to 0.96) in males and 0.97 (95 % CI, 0.94 to 0.98) in females, while negative predictive values of the test, where the participants whose I3M was ≥0.08 were minors, were 0.88 (95 % CI 0.85 to 0.90) in males and 0.97 (95 % CI, 0.94 to 0.98) in females. The likelihood ratios of the positive test (LR+) were 13.67 (95 % CI, 9.21 to 21.02) in males and 23.73 (95 % CI, 14.20 to 42.28) in females, while likelihood ratios of the negative test (LR-) were 0.12 (95 % CI 0.10 to 0.16) in males and 0.12 (95 % CI, 0.11 to 0.15) in females. Bayes post-test probabilities, p, were 0.94 (95 % CI 0.90 to 0.98) in males and 0.97 (95 %CI, 0.93 to 1.00) in females. These results indicate with high accuracy that I3M may be a useful alternative method in legal and forensic practice to discriminate individuals of black African origin who are around the legal adult age of 18 years in Botswana. Further studies should address the usefulness of this method and specific cut-off for different adolescent populations.

Validation of third molar maturity index (I 3M ) for discrimination of juvenile/adult status in South Indian population

“…Later the specific cut-off value of I3M <0.08 has been tested for different populations [22][23][24][25][26][27][28] , which further confirmed its applicability and reliability.…”

“…Cameriere et al 21 presented a method to assess the age of majority, which is based on the relation between real age and the proportions of widths of open apices and the tooth length of third molars. Later the specific cut-off value of I3M <0.08 has been tested for different populations [22][23][24][25][26][27][28] , which further confirmed its applicability and reliability.…”

“…Cameriere et al 21 have demonstrated the better performance of I3M <0.08 in discriminating adults or juveniles when compared to Demirjian staging (DS) system. The latter was successfully applied in various populations and proven to be a successful method in predicting the age of majority [22][23][24][25][26][27][28] .…”

Estimation of the age of senegalese children based on panoramic radiography of the third mandibular molar

“…Indeed the proceedings are different according to the age of the subject. 4,13,14,15 The most widely used method of determining dental age is the one described by Demirjian. 7 The third molar has an interest in estimating age because it is the last tooth to finish its evolution.…”

“…11 However, few studies have been carried out on the interest of the third molar in estimating the age of African subjects. 12,13 The objective of this preliminary study was to evaluate the interest of the third molar in the determination of the age of Senegalese subjects in panoramic radiography digitized by the Demirjian method.…”