Change in bone mineral density and tooth loss in Japanese community-dwelling postmenopausal women: a 5-year cohort study

The aim of this longitudinal study was to investigate the association between the change in bone mineral density (BMD) and tooth loss in Japanese community-dwelling postmenopausal women. The subjects were 404 women. At baseline (2005) and follow-up (2010), BMDs of the lumbar spine and right femoral neck were measured using dual-energy X-ray absorptiometry (QDR4500a) and participants were classified by tertiles of the annual percentage change in BMD. The number of teeth was counted at the baseline and follow-up to calculate the number of lost teeth over 5 years. Poisson regression analysis was conducted with tertiles of the changes in BMDs of the lumbar spine and femoral neck as the main exposures to estimate their influence on the number of lost teeth. Participants in the tertile with a greater decrease in BMD at each skeletal site (lumbar spine and femoral neck, respectively) had a larger number of lost teeth, controlling for possible confounders. The adjusted relative risks (95% confidence interval) for the mean number of lost teeth in the first, second, and third tertiles were 1.00, 1.15 (0.91-1.45), and 1.38 (1.11-1.72) for the lumbar spine and 1.00, 1.17 (0.93-1.47), and 1.27 (1.01-1.59) for the femoral neck, respectively. In conclusion, a significant relationship exists between a change in BMD and the number of lost teeth during 5-year study period in Japanese community-dwelling postmenopausal women.