Evaluating the Effectiveness of the Third Molar Maturity Index (I3m) and Mandibular Condyle Cortication for Determining the Legal Age (18) of Latvian Individuals

Background: It is important to accurately determine the legal age at which a person is considered and treated as an adult; in many countries, it is 18. With the increasing migration flow to European countries, accurate age estimation methods must be implemented. In this study, the third molar maturity (I3m) index and mandible condyle cortication stage were tested to distinguish adult from non-adult Latvian individuals using dental panoramic radiographs. Methods: This study included 716 selected dental panoramic radiographs of patients between the ages of 14 and 22. The lower-left third molar apical root parts were analyzed, and the I3m index was calculated. In addition, the condyle cortication stage was evaluated. Results: All logistic regression models achieved statistically significant results (p < 0.001). The accuracy was high for all groups (males: 0.90, females: 0.87, both genders: 0.89), and the sensitivity was lower than the specificity, particularly for females (sensitivity: 0.55). The I3m index appears to be a strong predictor across all models, while the mandibular condyle cortication stage plays a more nuanced role, depending on sex and the stage of condyle maturation. A higher I3m index value (greater than the cut-off of 0.095 in males) indicates a higher likelihood of being classified as a non-adult male for this model; however, in females, a cut-off point higher than 0.150 indicated a higher likelihood of being classified as a non-adult female. The new proposed cut-off values need to be tested on a new sample. Conclusions: The I3m index is a reliable age estimation tool, and a modified cut-off value could be determined for each gender in Latvian individuals. The condyle cortication stage is a weak tool for chronological age estimation in dental panoramic radiographs.