Introduction The receptor activator of nuclear factor-κB (RANK), the receptor for RANK ligand, is a member of the tumour necrosis factor receptor superfamily and plays a central role in osteoclast development. There is little epidemiological evidence as to whether RANK polymorphisms influence oral health. This study investigated the association between the RANK polymorphism and the number of teeth among Japanese.

Methods We used baseline data from the Shizuoka area in the Japan Multi-Institutional Collaborative Cohort Study. The analysis included 4927 subjects (3348 men, 1579 women; age range 35–69 years). The genotyping of the RANK polymorphism (rs12458117) was conducted using a PCR-based TaqMan method. The number of teeth was self-reported.

Results The mean tooth number was 24.2±5.6 (range 0–28) and decreased with age (p<0.01). The subjects with the GG genotype had significantly fewer teeth than those with the GA or AA genotype, after adjusting for sex, age and covariates (p=0.02). In a multivariate analysis after adjusting for covariates, men with the GG (OR, 2.6; 95% CI 1.1 to 2.1) and GA (OR, 1.4; 95% CI 0.7 to 1.6) genotypes had a higher risk of having less than 20 teeth, as compared to those with the AA genotype. No significant OR was found in women.

Conclusion Our findings suggest that the RANK polymorphism is related to tooth loss among Japanese men.