Structural and Qualitative Bone Remodeling Around Repetitive Loaded Implants in Rabbits

BACKGROUND: Bone mechanical function is regulated by bone quality and bone mineral density (BMD) that reflect bone strength. The preferential alignment of biological apatite (BAp) c-axis/collagen fibers and osteocytes is a determinant factor of bone quality. However, the effect of mechanical loading on bone quality around dental implants is unclear. PURPOSE: The aim of this study was to clarify the effects of mechanical loading on osseointegration, bone volume BMD, and bone quality around dental implants. MATERIALS AND METHODS: Twenty anodized Ti-6Al-4V alloy implants (KYOCERA Co., Kyoto, Japan) were placed in the proximal tibial metaphysis of 10 rabbits. Twelve weeks after surgery, mechanical loading was applied along the long axis of the implant (50 N, 3 Hz, 1,800 cycles, 2 days/week) for 8 weeks. Osseointegration, bone volume, BMD, and bone quality were evaluated using light microscopy, microcomputed tomography, polarized light microscopy, and microbeam X-ray diffractometer. RESULTS: Mechanical loading increased osseointegration, bone volume, and BMD. Bone quality around dental implant was altered with increased osteocyte numbers and the preferential alignment direction and degree of BAp c-axis/collagen fibers. CONCLUSIONS: These findings suggest that mechanical loading effectively induces bone anabolic responses around dental implants. Altered bone quality may upregulate bone strength, contributing to long-term implant stability.