Efficacy of photobiomodulation therapy on healing of ionizing irradiated bone: a systematic review of in vivo animal studies

This systematic review aimed to answer the research focused question: What are the effects of photobiomodulation (PBM) therapy on bone healing after ionizing irradiation in animal models? The EMBASE, LILACS, LIVIVO, PubMed, Scopus, and Web of Science databases, including gray literature, were searched using the following keywords: "Head and Neck Neoplasms"; "Ionizing Radiation"; "Low-Level Light Therapy"; and "Bone regeneration", focusing on the primary studies that assessed the effects of PBM therapy on animal models of irradiated bone. Six studies have met the eligibility criteria and presented an overall regular quality according to the risk of bias assessment tools. All the studies utilized rat animal model and near-infrared laser PBM at low power output setting. Most of the studies showed increased new bone formation, osteocytes, osteoblasts, and vascularization networking, as a result of PBM therapy. However, only one out of the six studies has not shown any differences in bone healing in both lased and non-lased animal groups. Nevertheless, PBM therapy is a potential tool to improve bone healing induced by ionizing radiation. However, due to the scarce number of studies and the great variability of laser parameters and treatment protocols, a clear conclusion cannot be drawn. Hence, extensive preclinical in vivo studies are warranted to ensure these beneficial effects have been addressed prior to translational clinical trials.