Phenothiazine Chloride and Soft Laser Light Have a Biostimulatory Effect on Human Osteoblastic Cells

Abstract

OBJECTIVE: Low-level laser therapy (LLLT) is a well accepted tool to accelerate wound healing and to reduce inflammation after oral implant insertion. Since there are no in vitro data on a combination of LLLT with prior photosensitization, it was the aim of this study to investigate if photosensitization with phenothiazine chloride results in an alteration of the biostimulatory effect of low-level laser irradiation. BACKGROUND DATA: LLLT and antimicrobial photodynamic therapy are well established for the treatment of peri-implantitis. In vitro studies have shown a biostimulatory effect of LLLT on various cell types, including osteogenic cells. MATERIALS AND METHODS: SaOS-2 cells were treated with the photosensitizer phenothiazine chloride before irradiation with matched laser light. At 24-h intervals the viability and differentiation were analyzed in treated and untreated cells. RESULTS: While the biostimulatory effect of the LLLT could be observed for the lower irradiation dose, the pretreatment with phenothiazine chloride did not significantly affect the growth and differentiation of the SaOS-2 cells. CONCLUSION: It can thus be concluded that combined treatment with phenothiazine chloride and LLLT does not result in a synergistic enhancement of the biostimulatory effect of LLLT, but there was also no evidence for antagonizing effects on growth and differentiation of human osteoblasts.