BACKGROUND Sexual dimorphism in teeth has been an area of research for forensic anthropologists. The function of root in transmitting the forces of occlusion to the alveolar bone varies as the force in males tends to be larger than in females. This shows the significance of the root length as indicators of sexual dimorphism. OBJECTIVE The aim of this study was to determine the presence of sexual dimorphism in the root lengths of permanent teeth and to evaluate if root length could be instrumental in defining sexual dimorphism among an ethnic Tamil population. METHODS Orthopantomograms of 1000 individuals (500 males and 500 females) were utilized, and the measurement of root length of permanent maxillary and mandibular teeth from canine to first molar on all four quadrants using the Digital software SCANORA 5.2.6. was carried out. Statistical analysis including descriptive statistics and independent Student t-test were performed. RESULTS In this study, the sexual dimorphism in root length is observed in 13, 14, 15, 16, 23, 26, 33, 36, 43, and 46 (mesial), and there is a statistically significant difference between the root measurements of males and females (P < 0.05). Most dimorphic teeth were maxillary canines and mandibular canines. CONCLUSIONS The data generated from this study suggest that the root length measurements present with a substantial evidence of sexual dimorphism emphasizing its importance on identifying sex and are therefore useful in determining the biological profile.