Association between mandibular third molar impactions and distal carious lesions on the adjacent second molars: A cross-sectional study

Objective This study aimed to evaluate the prevalence and patterns of impacted mandibular third molars (MTMs) and their association with distal caries in adjacent mandibular second molars (MSMs).Methods A total of 2000 randomly selected orthopantomograms (OPGs) were analyzed. MTM impaction patterns were classified using Winter's and Pell-Gregory systems, and distal caries on MSMs were assessed. Statistical analyses included chi-square tests and multivariate logistic regression to evaluate associations between impaction characteristics and caries prevalence.Results Of the 1594 eligible OPGs, 37% exhibited MTM impactions. Among the 828 impacted MTMs identified, 19.56% were associated with carious lesions on the distal surface of adjacent MSMs. Statistical analysis revealed that mesioangular impactions significantly increased the likelihood of distal caries in MSMs. In contrast, Pell-Gregory Classes II-C and III-C were associated with reduced odds of caries. Age emerged as a strong predictor, whereas gender and other Winter's classification categories did not significantly influence caries occurrence.Conclusion Impacted MTMs are associated with an increased risk of caries on the distal surface of MSMs. Impaction patterns and patient age influenced the prevalence of caries. Prophylactic removal of impacted MTMs in high-risk cases may help reduce the risk of caries development in MSMs.