The relationship between bone density and the oral function in older adults: a cross-sectional observational study

Falls among older adults with a low bone density can lead to a bedridden state. Declining bone density increases the risk of falls resulting fractures in older adults. A person's physical performance is known to be closely related to bone density, and a relationship between the physical performance and the oral function is also known to exist. However, there currently is a lack of evidence regarding the relationship between bone density and the oral function. We assessed the relationship between the bone density and the both the oral function and physical performance among older adults.

754 older adults aged 65 years or older who independently lived in rural regions and who were not taking any medications for osteoporosis participated. We checked all participants for osteoporosis using an ultrasonic bone density measuring device. Regarding the oral function, we evaluated the following factors: remaining teeth, occlusal support, masticatory performance, occlusal force, and tongue pressure. We also evaluated body mass index (BMI) and skeletal muscle mass Index as clinical characteristics. The normal walking speed, knee extension force and one-leg standing test were evaluated as physical performance. For the statistical analyses, we used the Mann-Whitney U test, chi-square test, the Kruskal-Wallis, and a multiple regression analysis.

Eighty-one percent of the females and 58% of the males had osteoporosis or a decreased bone mass. The occlusal force, masticatory performance and the tongue pressure showed significant association with the bone density. The participants physical performance showed a significant association with their bone states except for walking speed. According to a multiple regression analysis, clinical characteristics (sex, age, BMI), one-leg standing and occlusal force showed independent associations with the bone density. It was suggested that the bone density tends to increase if the occlusal force is high and/or the one-leg standing test results are good.

The bone density in the older adults showed a significant relationship not only with clinical characteristics or physical performance, but also with occlusal force. It may also be effective to confirm a good oral function in order to maintain healthy living for older adults.