Is smoking a predictor of apical periodontitis?

To evaluate the association between cigarette smoking and the frequency of apical periodontitis in female and male patients seeking treatment at the University of Basel (KREBS Project). This cohort study included full-mouth periapical radiographs of 161 subjects, including 66 current smokers, 26 former smokers and 69 individuals who had never smoked. The periapical region of all teeth was radiographically evaluated using the Periapical Index (PAI) score. Generalised linear mixed-effects models using the logit link were performed. The frequency of apical periodontitis differed based on gender and smoking status. Current male cigarette smokers with < 10 or a parts per thousand yen10 pack years showed frequencies of apical periodontitis of 12 % and 5.5 %, respectively, compared to 3.8 % in individuals who had never smoked. The corresponding data for female smokers were 5.7 % and 7.2 % in smokers with < 10 or a parts per thousand yen10 pack years, respectively, versus 5.2 % in individuals who had never smoked. The factors "prevalent coronal restoration" (p < 0.001), "prevalent root canal treatment" (p < 0.001) and "quality of root canal filling" (p < 0.001) were significant predictors for apical periodontitis. After adjustment for quality of root canal filling cigarette smoking was not associated with apical periodontitis in current female and male smokers with < 10 or a parts per thousand yen10 pack years (p > 0.05). Smoking status did not predict apical periodontitis in females and males in this sample group. With respect to quality of root canal filling, tobacco use may not be a significant predictor for apical periodontitis.