Is There a Relationship Between Periodontal Disease and Smoking After Adjusting for Job Classification in Japanese Employed Males?

Objectives: The objective of this study is to examine whether the well-known association between periodontal disease and smoking persists after adjusting for job classification. Methods: A sample of 16,110 employed Japanese males aged 20-69 years was included in the study. Periodontal examinations were conducted using the Community Periodontal Index. The association between periodontal disease and smoking status was examined using logistic regression adjusting for age, diabetes and job classification. Job classification was based on criteria of the Japanese Ministry of Health, Labour and Welfare. There are nine major job groups: (1) Professional (professionals, specialists), (2) Managers, (3) Office workers (computer operators, clerks, secretaries), (4) Skilled worker (factory workers, construction workers), (5) Salespersons (shop assistants), (6) Service occupations (superintendents, cleaners or car park attendants), (7) Security (guards), (8) Farmers and fishermen, (9) Transport and telecommunication workers (truck drivers). Results: Current and former smokers were more likely to have periodontal disease than non-smokers. Adjusting for job classification attenuated the association between smoking and periodontal disease but did not eliminate the association. The odds ratios for the association between smoking and Community Periodontal Index score 3 or 4 attenuated from 2.25 to 2.04 and from 2.62 to 2.52 for individuals aged 20 to 39 and 40 to 69 years, respectively. The effect of job classification on the association between periodontal disease and smoking was higher among younger participants aged 20 to 39 years. Conclusions: Smoking persisted as an important determinant of periodontal disease after adjusting for job classification in Japanese employed males. Keywords: inequality, job classification, periodontal status, smoking