Dose-dependent effect of smoking and smoking cessation on periodontitis-related tooth loss during 10 - 47 years periodontal maintenance—A retrospective study in compliant cohort

Aim: We retrospectively explored effects of smoking on tooth loss due to periodontitis (TLP) in long-term compliant patients. Materials and Methods: Chart data were collected from 258 patients undergoing post-non-surgical periodontal treatment (mean 2.24 visits/year) for 10–47.5 (mean 24.2) years. Patients were categorized as: (1) never smokers, (2) former smokers, (3) current light smokers (<10 cigarettes/day) and (4) current heavy smokers (≥10 cigarettes/day). Results: Of 6,590 teeth present at baseline (mean 25.6 teeth/patient), 264 teeth were lost due to periodontitis, corresponding to 0.03, 0.05, 0.08 and 0.11 TLP annually among never smokers, former smokers, current light smokers and current heavy smokers, respectively. A tooth from a current heavy smoker had 4.4-fold, 2.7-fold and 2.6-fold greater risk of TLP than a tooth from a never smoker, a current light smoker and a former smoker, respectively. Both heavy and light former smokers needed washout periods of approximately 15 years to reach the TLP risk level of never smokers. The TLP risk decreased by 6%/year of smoking cessation. Conclusions: It took almost 15 years of smoking cessation for the risk of TLP among former smokers to reach the level of never smokers. Hence, the 2018 periodontitis grading system should consider the impact of the “washout” period on former smokers.