Costa FO, et al. - In this study, researchers analyzed 212 individuals to examine the consequences of cumulative smoking exposure and duration of smoking cessation on the recurrence of periodontitis over a 6-year follow-up period. They divided subjects into 3 groups according to smoking habits: non-smokers (NS; n=95), former smokers (FS; n=22), and current smokers (CS; n=25). They recorded the recurrence of periodontitis in NS, FS, and CS groups as 44.2%, 68.2%, and 80.0%, respectively. After adjusting for confounders, they found the odds ratio for the recurrence of periodontitis after 6 years to be 2.80 for FS and 5.97 for CS. They observed a significant dose-response association between pack-years of smoking and the recurrence of periodontitis. They found a significant reduction in the risk for periodontitis recurrence as the years of smoking cessation increased.