The objectives of this study were to evaluate the prevalence and location of root proximity between disto-inclined mandibular second molars (7D) and adjacent first molars (6D), to examine the occlusal inclination and root curvature of 7D and 6D, compared with their normal counterparts (7N, 6N), to compare the interradicular space between 7D:6D and 7N:6N, and to evaluate the relationship between occlusal inclination and root curvature of 7D. 70 digital panoramic radiographs were studied. Image J software was used to measure occlusal inclination, root curvature at middle third and apical third of mesial and distal roots, and interradicular space of 7D:6D and 7N:6N. Paired t-tests and Pearson’s correlation analysis were used to compare differences between sides and to examine the relationship between variables, respectively. Root proximity was found in 62 from 70patients (88.57 %). Statistical significant differences of the occlusal inclination between 7D and 7N was found (mean difference = 13.50°; P<0.05). A similar finding was observed between 6D and 6N (mean difference = 1.61°; P<0.05). In 7D, apical third of both roots significantly curved distally (P<0.05). No association between occlusal inclination and root curvature of 7D was found.
In conclusion, the findings of this study suggested that when 2^nd molars are disto-inclined, distally curved roots of the 2^nd molar, shifted occlusal inclination of both 1^st and 2^nd molars and root proximity between them may be expected. Early diagnosis and treatment may be advantageous in the prevention of root curvature and proximity problems.