Purpose: It is known that the low-power irradiation of a high-output laser accelerates wound healing. However, there is little fundamental research on it, especially for cultured osteoblasts. The purpose of this study was to evaluate the effect of low-level irradiation of a hard laser on cultured osteoblasts. Materials and Methods: Osteoblasts cultured in collagen gel were irradiated using either a CO2 or a semiconductor laser. Expressions of OC, BSP, and HSP27 were examined at 3 days after irradiation and calcium volumes were measured after 1 week. Results: In the CO2 laser group, a significant difference was only observed with 2.6-W laser irradiation. There was no promoting effect of semiconductor laser irradiation. Additionally, the highest expression of HSP27 was shown with 2.6 W of CO2 laser irradiation. Conclusion: The CO2 laser at 2.6 W can increase the calcification of osteoblasts in three-dimensional cultures. The mechanism seems to be related to the cascade of HSP27.
Keywords: carbon dioxide laser, semiconductor laser, calcification, heat shock protein 27, osteoblast, low-level irradiation