A Thermal and Biological Analysis of Bone Drilling.

With the introduction of high-speed cutting tools, clinicians have recognized the potential for thermal damage to the material being cut. Here, we developed a mathematical model of heat transfer caused by drilling bones of different densities and validated it with respect to experimentally measured temperatures in bone. We then coupled these computational results with a biological assessment of cell death following osteotomy site preparation. Parameters under clinical control, e.g., drill diameter, rotational speed, and irrigation, along with patient-specific variables such as bone density were evaluated in order to understand their contributions to thermal damage. Predictions from our models provide insights into temperatures and thresholds that cause osteocyte death and that can ultimately compromise stability of an implant.

An osteopenic/osteoporotic phenotype delays alveolar bone repair.

Aging is associated with a function decline in tissue homeostasis and tissue repair. Aging is also associated with an increased incidence in osteopenia and osteoporosis, but whether these low bone mass diseases are a risk factor for delayed bone healing still remains controversial. Addressing this question is of direct clinical relevance for dental patients, since most implants are performed in older patients who are at risk of developing low bone mass conditions. The objective of this study was to assess how an osteopenic/osteoporotic phenotype affected the rate of new alveolar bone formation. Using an ovariectomized (OVX) rat model, the rates of tooth extraction socket and osteotomy healing were compared with age-matched controls. Imaging, along with molecular, cellular, and histologic analyses, demonstrated that OVX produced an overt osteoporotic phenotype in long bones, but only a subtle phenotype in alveolar bone. Nonetheless, the OVX group demonstrated significantly slower alveolar bone healing in both the extraction socket, and in the osteotomy produced in a healed extraction site. Most notably, osteotomy site preparation created a dramatically wider zone of dying and dead osteocytes in the OVX group, which was coupled with more extensive bone remodeling and a delay in the differentiation of osteoblasts. Collectively, these analyses demonstrate that the emergence of an osteoporotic phenotype delays new alveolar bone formation.