Background: To date only a few studies have evaluated the long-term influence of smoking and smoking cessation on periodontal health. The present study, therefore, was undertaken with the aim to prospectively investigate the influence of smoking exposure over time on the periodontal health condition in a targeted population before and after a follow-up interval of 10 years.
Methods: The primary study base consisted of a population of occupational musicians that was investigated the first time in 1982 and scheduled for reinvestigation in 1992 and 2002. The 1992 investigation included 101 individuals from the baseline study constituting a prospective cohort including 16 smokers, who had continued to smoke throughout the entire length of the 10-year period; 28 former smokers who had ceased smoking an average of approximately 9 years before the commencement of the baseline study; 40 non-smokers, who denied ever having smoked tobacco; and 17 individuals whose smoking pattern changed or for whom incomplete data were available. The clinical and radiographic variables used for the assessment of the periodontal health condition of the individual were frequency of periodontally diseased sites (probing depth > or =4 mm), gingival bleeding (%), and periodontal bone height (%). The oral hygiene standard was evaluated by means of a standard plaque index.
Results: The changes over the 10 years with respect to frequency of diseased sites indicated an increased frequency in continuous smokers versus decreased frequencies in former smokers and non-smokers. Controlling for age and frequency of diseased sites at baseline, the 10-year change was significantly associated with smoking (P <0.001). The differences between current smokers and non-smokers, and between current and former smokers, respectively, were statistically significant (P<0.001). Moreover, the 10-year change increased significantly with increasing smoking exposure controlling for age (P= 0.01). In terms of periodontal bone height, the 10-year changes implied statistically significant reductions within current as well as former smokers (P <0.001 and P <0.05, respectively), but not within non-smokers. The overall change was significantly associated with smoking controlling for age and bone height level at baseline (P<0.01), including statistically significant differences between current smokers and non-smokers and between current and former smokers, respectively (P<0.05). Moreover, the 10-year bone height reduction increased significantly with increasing smoking exposure controlling for age (P <0.05). With regard to gingival bleeding, the 10-year differences between smoking groups were not statistically significant. Plaque index remained low throughout in all smoking groups at an overall average level of about 0.8.
Conclusions: The results suggest that periodontal health is compromised by chronic smoking as evidenced by an increase of periodontally diseased sites concomitant with loss of periodontal bone height, as compared to non-smokers whose periodontal health condition remained unaltered throughout the 10-year period of investigation. The periodontal health condition in former smokers, similar to that of non-smokers, remained stable, suggesting that smoking cessation is beneficial to periodontal health.