© 2021 Australian Academy of Forensic Sciences.The present study aimed to assess the performance of second (I2M) and third (I3M) molar maturity indices, the sum of both indices (I2M+3M), and the sum of the seven mandibular teeth indices (S) in terms of determining whether an individual is at least 12 or 15 years old. The panoramic radiographs of 763 individuals aged between 10–17 years were analysed. For the 12-year age threshold, I2M was found to be the highest specific indicator for both sexes. The optimal cut-off values for the I2M were determined to be 0.072 in females and 0.106 in males. The sensitivity, specificity, and area under the ROC curve (AUC) were 0.749, 0.978, and 0.925 in females, while they were 0.776, 0.953, and 0.925 in males, respectively. With regard to the 15-year age threshold, an optimal I2M cut-off value of 0.026 was established for females, as it showed the best discriminative ability. The sensitivity, specificity, and AUC were 0.893, 0.779, and 0.885, respectively. For males, an optimal cut-off value of 0.593 was obtained for I2M+3M with the highest specificity (0.900) and AUC (0.931) as well as a sensitivity of 0.857. In conclusion, the identified cut-off values may represent alternative methods in forensic age diagnostics.