Association of impacted mandibular third molar with caries on distal surface of second molar

Objective: To evaluate the relationship of impacted mandibular third molars (M3M) status with caries on distal surface (CODS) of mandibular second molars (M2M). Material and Methods: A retrospective study on digital panoramic radiographs. Information on age, gender, eruption status of impacted mandibular third molars and mandibular second molars caries on distal surface were recorded. Winters’ classification and Pell and Gregory classification were used to classify impacted mandibular third molars. The Chi-square test and Poisson regression were used. A p-value of <0.05 was considered statistically significant. Results: A total of 1497 radiographs were evaluated out of which 2704 sites were recorded. A total of 33.2% M3M were impacted and 1053 (38.9%) M2M had caries on distal surface. Among the total M3M teeth, 39.1% of erupted and 38.6% of impacted teeth had CODS of M2M. However, there was no significant difference in the distribution of CODS of M2M in erupted and impacted mandibular third molars teeth (p=0.796). As per Winters classification, mesio-angular and horizontal impaction types were significantly associated with CODS (p<0.001). Conclusion: All impacted mandibular third molars may not be associated with caries on distal surface of mandibular second molars. But, the angulation like mesioangular and horizontal, class I and II may predispose to caries on distal surface of mandibular second molars.