부산대학교 도서관

Low Level Laser Therapy (LLLT) using CO2 lasers is known to activate surrounding cells and tissue. However, few studies concerning LLLT using hard lasers have been perform, and much about the biological mechanism of LLLT. In the present study, we report morphological changes in rat tibiae irradiated by CO2 laser without surgical treatment. The purpose of this study was to histologically evaluate the effects of LLLT using a CO2 laser on bone formation in rat tibiae. The left tibiae underwent CO2 laser irradiation, while the right tibia did not undergo CO2 laser irradiatio (Control). Rat tibiae were irradiated by CO2 laser from the outside of the body.Irradiation was performed at the following power and exposure time: power, LOW; duration: 15 min; calculated energy density, -1.1KJ/cm2. On the 7th day after irradiation, tibiae were removed and were analyzed by Soft X-ray. Serial sections were prepared for osteoid staining (Yoshiki's method) and ALP (Alkalinephosphatase) staining, and were examined for mineralized apposition rate (Calcein labeling). Soft X-ray examination revealed no differences between the control and CO2 laser-irradiated groups. However, marked osteoid formation (Yoshiki's method) on the surface of laser-irradiated tibiae and young ALP-positive osteoblasts were present in the osteoid tissue. Interestingly, calcein labeling demonstrated that mineral apposition rate on the periosteum of laser-irradiated cortical bone was much higher than that in control tibia. These results demonstrate that LLLT using CO2 laser induced not only mineralization but also osteoblast differentiation. The present study suggests that CO2 laser can be applied to bone regeneration treatment. (J. Jpn. Soc. Laser Dent. 16: 23-30, 2005 Reprint request to Dr. YOKOSE) Key words=LLLT, Bone regeneration, CO2 laser