FcgammaRIIIb genotypes and smoking in periodontal disease progression among community-dwelling older adults in Japan

BACKGROUND: FcgammaRIIIb genotypes and smoking are risk factors for periodontal disease. However, the interaction of FcgammaRIIIb- NA1-NA2 polymorphism with smoking remains unclear. The purpose of this study was to determine if FcgammaRIIIb-NA1-NA2 polymorphism and smoking are associated with periodontal disease progression among elderly people. METHODS: Among 70-year-old subjects, 164 with neither diabetes mellitus nor blood sugar > or =140 mg/dl, who had more than 20 teeth and who could participate in both the baseline and the follow-up examinations were included in the study. The NA1 group comprised subjects with FcgammaRIIIb-NA1NA1 genotype (N = 53), while the NA2 group included subjects with FcgammaRIIIb-NA1NA2 or NA2NA2 genotype (N = 111). We examined the progression of periodontitis by measuring attachment loss during 3 years. RESULTS: The frequency of subjects who showed > or =4 mm additional attachment loss at one or more sites was 55.6% for smokers and 37.2% for non-smokers. The odds ratio (OR) was 2.13 (confidence interval CI]: 0.92 to 4.76). We found a better association between periodontal progression and smoking in the NA2 group. The OR for smokers was 3.03 (CI:1.12 to 8.33, P = 0.028). Additionally, the mean number of sites with > or =4 mm additional attachment loss per person between smokers and non-smokers in the NA2 group or between smokers and non-smokers in the NA1 group was 2.90 3.42 and 0.74 1.53 or 0.57 0.79 and 0.68 1.03, respectively (P <0.001; analysis of variance ANOVA]). CONCLUSION: Our results may suggest an association between smoking and periodontal disease progression in elderly people with FcgammaRIIIb-NA2 polymorphism.