Bone Density and the Number of Teeth in Elderly Women

Objectives: Osteoporosis is a disease predominantly found in women and is characterized by loss of bone density. Previous studies have suggested that low bone density is related to aging, lack of exercise, nutritional deficiency, and lifestyle-related disease. The aim of this study was to examine the relationship between bone density and the number of teeth in elderly women.
Methods: The subjects of this study were 87 elderly women in nursing homes and 52 elderly women living independently in Aichi Prefecture, Japan. Bone density was evaluated using quantitative ultrasound (ultrasonic bone densitometer Benus; Ishikawa Seisakusho, Kanazawa, Japan) by calculating the speed of sound ［SOS(m/s): ultrasound velocity through the heel］. The SOS was divided into two categories of low: <1,550 (n = 39) and high: ≥ 1,550 m/s (n = 100). Univariate analyses with the Mann-Whitney U-test and the chi-square test were used to examine the relationship between SOS and each independent variable. Factors significantly associated with SOS were entered into a multivariate logistic regression analysis.
Results: Univariate analyses revealed that age, nutritional status, activities of daily living, and number of teeth were significantly associated with SOS (p < 0.001). No significant relationships were detected between SOS and the presence of systemic disease or previous fracture. The multivariate logistic regression analysis showed that subjects with fewer than 10 teeth had a significantly higher odds ratio (3.57; 95% confidence interval, 1.32-9.63) for having a low SOS suggesting low bone density compared with subjects with ≥ 20 teeth, independent of other confounding variable.
Conclusions: These results suggest that losing teeth may be a risk factor for low bone density due to a nutritional deficiency.This work was supported by Grant-in-Aid of Scientific Research (C) 16K11875 from the Ministry of Education, Science, Sports and Culture of Japan.