Photobiomodulation Therapy in Bone Repair Associated with Bone Morphogenetic Proteins and Guided Bone Regeneration: A Histomorphometric Study

Objective: To evaluate the efficacy of photobiomodulation for bone repair of critical surgical wounds with implants of bone morphogenetic proteins (BMPs) and bovine biological membranes, using histological and histomorphometric analysis. Background: Tissue engineering has been developing rapidly through the use of various biomaterials for the treatment of bone defects, such as mechanical barriers consisting of biological membranes and implants of biomaterials for bone supply. Materials and methods: Thirty-two male rats were divided into four groups (n=8): group I-C: control; group II-PT: photobiomodulation therapy; group III-PM: Gen-Pro((R)) BMPs+Gen-Derm((R)) membrane; and group IV-PMPT: Gen-Pro((R)) BMPs+Gen-Derm((R)) membrane+photobiomodulation therapy. A 3mm bone cavity was performed in the upper third of the lateral surface of the right rat femur to obtain a bone defect considered to be critical. The irradiated groups received seven applications of AlGaAs diode laser 830nm, P=40mW, continuous wave (CW) emission mode, f approximate to 0.6mm, 4J/cm(2) per point (north, south, east, and west) at 48h intervals, for a total of 16J/cm(2) per session (final dose: 112J/cm(2)). Bone repair was evaluated at sacrifice 15 and 30 days after the procedure. The specimens were embedded in paraffin and stained with hematoxylin and eosin and Picrosirius for analysis by light microscopy and by the Leica interactive measurement module software. Statistical analysis was performed (p<0.05%). Results: Histological analysis confirmed the histomorphometric results, with the experimental groups showing bone neoformation of significantly higher quality and quantity at the end of 30 days compared with the control group. Conclusions: Photobiomodulation therapy was effective for bone repair mainly when associated with BMPs and a biological membrane. The results of this study are promising and stimulate further scientific and clinical research.