Accuracy of the third molar index for assessing the legal majority of 18 years in Turkish population

In the last few years, forced and unregistered child marriage has widely increased into Turkey. The aim of this study was to test the accuracy of cut-off value of 0.08 by measurement of third molar index (I3M) in assessing legal adult age of 18 years. Digital panoramic images of 293 Turkish children and young adults (165 girls and 128 boys), aged between 14 and 22 years, were analysed. Age distribution gradually decreases as I3M increases in both girls and boys. For girls, the sensitivity was 85.9% (95% CI 77.1-92.8%) and specificity was 100%. The proportion of correctly classified individuals was 92.7%. For boys, the sensitivity was 94.6% (95% CI 88.1-99.8%) and specificity was 100%. The proportion of correctly classified individuals was 97.6%. The cut-off value of 0.08 is a useful method to assess if a subject is older than 18 years of age or not.