Introduction <p>Accurate estimation of legal adulthood in undocumented individuals remains a major challenge in forensic and medico-legal contexts. This study evaluates mandibular condylar cortication and third molar apical closure assessed by cone beam computed tomography (CBCT) as potential indicators of age of majority. A retrospective observational pilot study was conducted on 142 individuals aged 13–25 years from six geographic regions (Spain, Uruguay, Peru, Mexico, Venezuela and Colombia). Two radiological variables were analyzed: the presence of cortical bone in the mandibular condyle and apical closure of the mandibular third molars. Associations with chronological age were explored descriptively, considering sex and geographic origin.</p> Results <p>Mandibular condylar cortication was identified exclusively in individuals aged 18 years or older. It showed 89.2% sensitivity, 100% specificity, 100% positive predictive value, and 89.5% negative predictive value for identifying legal adulthood. Complete third molar apical closure showed lower sensitivity (64.7%) and specificity of 96.6%. Both markers were significantly associated with legal adulthood (Fisher’s exact test, <i>p</i> &lt; 0.001). </p> Conclusion <p>Within the limitations of this pilot study, mandibular condylar cortication assessed by CBCT appears to be a promising indicator of legal adulthood, potentially offering higher specificity than third molar apical closure. Further large-scale studies are required to validate these findings.</p>