Osteoporosis Therapeutic Effects on Alveolar Bone Properties

Objectives: Parathyroid hormone (PTH) and bisphosphonate have been used to treat osteoporosis caused by postmenopausal estrogen deficiency. These agents provide anabolic and anti-catabolic effects on bone remodeling to increase bone mass and its mechanical integrity for bearing loads. Alveolar bone (AB) surrounding teeth is subject to active remodeling that is stimulated by combination of occlusal static and masticatory dynamic loading. Thus, the objective of this study was to examine whether these therapeutic agents for osteoporosis alter characteristics of the AB.
Methods: Thirty 4-month female rats were obtained following IACUC approval. 24 rats were ovariectomized (OVX) to cause estrogen deficiency and 6 rats was assigned for Sham surgery. The 6 OVX rats were assigned to each non-treatment (OVX), PTH, a bisphosphonate (alendronate (ALN)), and PTH+ALN treatments groups. Mandibles were dissected and the rat molar was compressed by static loading up to 7N and dynamic mechanical analysis (DMA) using a non-invasive compressive cyclic loading (-5±4N at 1 to 3 Hz) to measure static stiffness (K) and dynamic energy dissipation (tan δ), respectively. Then, the rat mandibles were scanned by micro-computed tomography (micro-CT) (20 micron voxel). Mean tissue mineral density (TMD) and volume of the AB were obtained using the 3D micro-CT images. Pearson’s correlations were examined between the measured values. Analysis of covariance was also tested to investigate the treatment effects (significant, p<0.05).
Results: The TMD and volume of AB had a significantly positive correlation (p<0.001) while the K and tan δ had a significantly negative correlation (p<0.001). Both correlations were significantly different between the treatment groups (p<0.025).
Conclusions: The current results indicate that quality (TMD) is improved with increasing quantity (volume), and responses to static and dynamic loadings are balanced at the AB. The agent treatments did not have significant effects on determining these properties at the AB.