Association between passive and active smoking evaluated by salivary cotinine and periodontitis

Aim: This study attempted to determine the relationship between passive and active smoking on the basis of salivary cotinine levels and periodontitis severity. Methods: Japanese workers (n=273) were surveyed via an oral examination, a self-administered questionnaire and collection of whole saliva. Probing pocket depth (PPD) and clinical attachment level (CAL) served as periodontal parameters. Periodontitis was defined as the presence of two or more teeth with PPD 3.5 mm and CAL 3.5 mm. Salivary cotinine was determined using ELISA. Statistical methods included Wilcoxon's rank-sum test and multiple logistic regression analysis. Results: Based on the results of receiver-operating characteristic plots for cotinine-level classification derived from self-reported smoking status, non-, passive and active smokers were defined as those subjects exhibiting cotinine levels of 0, 1–7 and 8 ng/ml, respectively. Numbers of teeth displaying CAL 3.5 mm in passive and active smokers were significantly higher than those in non-smokers. Multiple logistic regression analysis revealed significantly higher periodontitis odds ratios in passive and active smokers relative to non-smokers following adjustment for other lifestyle factors; odds ratios were 2.87 [95% confidence interval (CI); 1.05–7.82] and 4.91 (95% CI; 1.80–13.35), respectively. Conclusion: These findings suggest that passive smoking classified in terms of salivary cotinine level may be an independent periodontitis risk indicator.