Laser Therapy on the early stages of healing bone defects

OBJECTIVE: The purpose of the study was to demonstrate the biological effects of low-level laser therapy (LLLT) and bovine bone graft on the early stages of femur fractures using histological studies. METHODS: Thirty-six Wistar rats were divided in 3 groups (LLLT, LLLT + graft and control) submitted to femur osteotomy and bovine bone graft. The animals were irradiated transcutaneuosly at four points around the defect every 48 h. At each point a dose of 5 J/cm2 was given and the total dose per session was 20 J/cm2. The animals were euthanased at 1 and 3 days after surgery. For the histopathological analysis, the following parameters were used in the periosteum, external soft and fracture gap: acute inflammation, angiogenesis, deposition of the collagen, presence of bone reabsorption and bone deposition. RESULTS: In all groups of the experiment was observed an initial stage of the healing process (one day after the fracture) with the presence of hematoma and acute inflammation. However, in the third day of healing process a well developed collagen deposition was observed in LLLT group and LLLT + graft when compared with the control group in which a poorly organized scar was revealed. In addition, a higher number of vessels were observed in LLLT group and LLLT + graft than that observed in control group. Finally, in LLLT group was observed an increase of the bone repair at early bone healing process with the presence of demineralized bone. This findings described above were not observed in the LLLT + graft group in which a well developed cellular periosteum is detected but no imatture bone is observed. CONCLUSION: It is concluded that a positive biomodulative effect on the early stages healing process of one defects associated or not to the use of bovine bone graft on the femur of rats.