Background: The aim of this study is to determine the effect of cigarette smoking on the severity of periodontitis in a crosssectional study of older Thai adults.

Methods: The study population consisted of 1,960 subjects (age 50 to 73 years old). All subjects received both medical and dental examinations. Periodontal examinations, including plaque score, probing depth, and clinical attachment level, were done on all teeth present in two diagonal quadrants. Sociodemographic characteristics and smoking status were obtained by questionnaires. Multinomial logistic regression was used to address the association between cigarette consumption and mean clinical attachment level.

Results: In this study population, 48.7% were non-smokers, 14.4% were current smokers, and 36.9% were former smokers. Current smokers had higher percentage of sites with plaque, deeper mean probing depth, and greater mean clinical attachment level than former smokers and non-smokers. The odds of having moderate and severe periodontitis for current smokers were 1.7 and 4.8 times greater than non-smokers, respectively. Former smokers were 1.8 times more likely than non-smokers to have severe periodontitis. Quitting smoking reduced the odds of having periodontitis. For light smokers (<15 packyear), the odds for severe periodontitis reverted to the level of non-smokers when they had quit smoking for ≥10 years. For moderate and heavy smokers (≥15 packyear), the odds of having severe periodontitis did not differ from those of non-smokers when they had quit smoking for ≥20 years.

Conclusions: There was a strong association between cigarette smoking and the risk of periodontitis among older Thai adults. Quitting smoking appears to be beneficial to periodontal health. J Periodontol 2005;76:566-572.