Age-related changes of bone mineral density in mandible by quantitative computed tomography.

Quantitative Computed Tomography (QCT) was used to investigate age-related changes in trabecular bones of the mandible. The volumetric Bone Mineral Density (vBMD) of mandibles was found to be increasing with aging in the 20-29, 30-39, 40-49 age groups, while resulted decreasing in the 50~ years age group in a Chinese population. The aim of this study was to validate QCT as a reliable method to measure the vBMD of the mandible and to assess vBMD of the mandible in a Chinese population. A total of seven hundred and eighteen volunteers (299 males, 419 females), ranging from 20 to 63 years of age, previously enrolled in another study, were included for vBMD measurements by QCT. A total of 50 subjects were enrolled for the validation of QCT measurement. Basic information (age, height and weight), and vBMD of the mandible (middle, body and angle) were recorded. Comparisons among age and sex groups were analyzed using the Mann-Whitney test. Linear correlation analysis between vBMD and age was performed. The mandibular vBMD was twice measured with QCT by one operator and resulted highly repeatable (ICC 0. 97, P 0. 05). The vBMD in the middle of the mandible was the highest, followed by that in the body and at the angle of mandible. In each age group, the mean vBMD increased with aging except for the 50~ years age group (P less than 0.05) in which it decreased. The mean mandibular vBMD was higher in females than males in each age group (P less than 0.05). Correlation between vBMD and age was statistically significant (r=0.15, P less than 0.01). QCT shows high precision for the measurement of BMD in the mandible. The present study provides normative data of the mandible in an age- and sex-stratified manner, which can be helpful in clinical practice.