Validation of third molar maturity index (I3M) for discrimination of juvenile/adult status in South Indian population

216 panoramic radiographs (114 females and 102 males) of living subjects aged between 14 and 21 years were analyzed. Our results demonstrated high sensitivity (83.3% and 90.2%) and specificity (98.3% and 95.1%) for females and males respectively. The positive likelihood ratios of being adult were 50.00 and 18.35 while the negative likelihood ratios were 0.17 and 0.10 in females and males respectively. The estimated posttest probability was 98.0% in females and 94.8% in males. The obtained results showed that the specific cut-off value of I3M < 0.08 may be a useful additional tool in discrimination of individuals who are around 18 years of age.