The relationship between bone mineral density and the number of remaining teeth in community-dwelling older adults

Tooth loss and osteoporosis may share common aetiologic agents which influence the process of both diseases. The purpose of this study was to evaluate the relationship between bone mineral density (BMD) of the os calcis and the number of remaining teeth, controlling the known confounding factors. Among all 70-year-old inhabitants in Niigata City, Japan, 600 people were selected randomly in order to have approximately the same number of each gender. We analysed 460 subjects. We evaluated the BMD of the os calcis using an ultrasound bone densitometer, then we counted the number of remaining teeth excluding the third molars. Stiffness is a clinical index which is calculated by the spread speed of supersonic waves. To monitor the general health condition of the subjects, serum levels of disease markers and smoking habits were also investigated. The mean number of remaining teeth for the osteopenia group (OG) and the no-osteopenia group (NOG) was 15.97 +/- 9.98 and 18.31 +/- 8.06, respectively in females, and 16.32 +/- 9.93 and 18.12 +/- 9.33, respectively in males (OG versus NOG, P = 0.047 by two-way ANOVA). In addition, stiffness was significantly associated with the number of remaining teeth (CV = -0.157, P = 0.005) using linear multiple regression analysis adjusted by four other variables. In this study, there was a significant relationship between the number of remaining teeth and BMD of the os calcis.