Evaluation of the Effects of Photobiomodulation on Bone Healing in Healthy and Streptozotocin-Induced Diabetes in Rats.

Abstract

This study aimed to assess the effects of Photobiomodulation (PBM) with pulsed wave laser on Hounsfield unit (HU) and bone strength at a catabolic response (bone resorption) of a callus bone defect in healthy and streptozotocin (STZ)- induced type I diabetes mellitus (TI DM) in rats. Conflicting results exist regarding the effect of PBM on bone healing in healthy and diabetic animals. We randomly divided 20 adult female rats into the following groups: (1) control, no TI DM, and no PBM; (2) no TI DM and PBM; (3) TI DM and no PBM; and (4) TI DM and PBM. TI DM was induced by STZ. All rats underwent partial transversal standardized osteotomies in their right tibias. The rats received PBM (890 nm, 80 Hz, 1.5 J/cm2) thrice per week during 30 days. At 4 weeks after the surgery, the rats were sacrificed and their tibias submitted to computed tomography scanning to measure HU. The samples underwent a three-point bending test to evaluate bone strength. Analysis of variance (ANOVA) (p = 0.013) results showed that treatment by PBM significantly increased the biomechanical property (stress high load) of the callus defect from the partial tibia osteotomy in healthy rats compared to the control groups. However, we observed no significant increase in the biomechanical properties of the laser-treated diabetic bone defect compared to the control diabetic group. The ANOVA for the HU of callus density produced a p value of 0.000. A significant increase existed in the mean callus density in the healthy groups compared to the diabetic groups. The 80-Hz laser did not significantly enhance bone repair from an osteotomy of the tibia in an experimental model of TI DM rats.