HEALING OF BONE DEFECTS PREPARED USING THE ERBIUM-YAG LASER

Many in vitro studies have described the minimal thermal damage associ ated with the erbium-YAG laser during preparation of cuts in bone. How ever, not all of the in vivo studies have shown improved healing of la sed bone over the more conventional methods of bone surgery. In this i n vivo study, 26 mature rats were used. Under general anaesthesia, a s lot was produced in the tail bones of each rat using the erbium-YAG la ser and a conventional burr. The rats were killed at intervals over a 24-day period, and the tail bones collected in neutral buffered formal in, decalcified and prepared for routine wax histology. The main histo logical differences occurred at 9 and 10 days after surgery, when the bone trabeculae formed following laser surgery appeared to extend into the marrow from the cortical defect in long, narrow finger-like proje ctions. The migration of fibroblasts from the periosteum following las er surgery, and their subsequent differentiation into osteoblasts in t he marrow may be responsible for this histological pattern. Surgery wi th the burr produced a coarse trabecular pattern limited to the outer cortical region.