Cumulative smoking exposure and cessation associated with the recurrence of periodontitis in periodontal maintenance therapy: A 6-year follow-up

Background This study followed individuals in periodontal maintenance therapy (PMT) over 6 years and longitudinally evaluated the effects of cumulative smoking exposure and duration of smoking cessation on the recurrence of periodontitis. Methods From a 6-year follow-up cohort study with 212 individuals in PMT, 142 patients who attended at least one PMT visit within 12 months were determined to be elegible. According to smoking habits they were categorized into three groups: non-smokers (NS; n = 95), former smokers (FS; n = 22), and current smokers (CS; n = 25). Complete periodontal examination and smoking habits were evaluated at two instances: T1 (first time, after active periodontal therapy) and T2 (second time, 6 years). Associations between the recurrence of periodontitis (RP; probing depth >= 4 mm and clinical attachment loss >= 3 mm, together with the presence of bleeding on probing and/or suppuration), smoking status, and potential risk variables were analyzed by univariate and multivariate analysis, when appropriate. Results The RP in NS, FS, and CS groups was 44.2%, 68.2%, and 80.0%, respectively. After adjusting for confounders, odds ratios (95% confidence interval) for the RP in T2 was 2.80 (2.11 to 5.14) for FS and 5.97 (3.58 to 9.88) for CS. There was a significant dose-response relationship between pack-years of smoking and the RP, as well as a significant decrease in the risk for the RP as the years of smoking cessation increased. Conclusion During 6 years of PMT, cumulative smoking exposure and shorter time since smoking cessation were significantly associated with the RP.