Dr. Friedman is correct that pathology associated with 2nd molars adjacent to erupted and partially erupted 3rd molars is well known (Garaas et al., 2011; Falci et al., 2012; Friedman, 2014). Our article sought to categorically define the risk posed to adjacent 2nd molars by unerupted, erupted, or absent 3rd molars (Nunn et al., 2013). Previously, the most comprehensive study was The Third Molar Clinical Trials (White, 2007). However, these included only patients with 4 retained asymptomatic 3rd molars and adjacent 2nd molars. Our study included participants with any retained asymptomatic 3rd molars and adjacent 2nd molars and also those with absent 3rd molars. Inclusion of these additional categories allowed for comparison of bony-impacted, soft-tissue–impacted, erupted, and absent 3rd molars on the risk of 2nd molar pathology, which is a novel contribution of our study. Dr. Friedman is also correct about the low prevalence of soft-tissue–impacted 3rd molars in our study cohort. Nevertheless, the associated absolute risks for 2nd molar tooth loss and 2nd molar pathology are substantial (Table). Importantly, we found that bony-impacted 3rd molars posed no more risk to adjacent 2nd molars than did erupted 3rd molars. This information may be useful in guiding decision-making by patients with various types of unerupted 3rd molars. Analysis of our data clearly indicates that any potential benefit to 2nd molars of prophylactic removal of 3rd molars is related to the type of 3rd molar status. Last, our findings should not be inferred as justifying the prophylactic removal of asymptomatic 3rd molars. Rather, these findings are consistent with the approach of ‘watchful waiting’. Table. Absolute Risk over Course of Study

Prophylactic extraction of unerupted asymptomatic third molars is the most common oral surgery procedure in the United States. However, limited evidence exists to justify its costs and associated morbidity. We analyzed data collected over 25 years from 416 adult men enrolled in the Veterans Affairs Dental Longitudinal Study to evaluate the association of retained asymptomatic third molars with risk of adjacent second molar pathology (caries and/or periodontitis), based on third molar status (i.e., absent, erupted, or unerupted). Unerupted molars were further categorized as either soft tissue or bony impacted. We found that the lowest prevalence and incidence of second molar pathology occurred when the adjacent third molar was absent. The presence of a third molar that was soft tissue impacted increased the risk of incident second molar pathology 4.88-fold (95% confidence interval: 2.62, 9.08). Having an erupted or bony impacted third molar increased the risk of incident second molar pathology by 1.74 (95% confidence interval: 1.34, 2.25) and 2.16 (95% confidence interval: 1.56, 2.99), respectively. The retention of third molars is associated with increased risk of second molar pathology in middle-aged and older adult men.