Effects of low-level laser therapy on bone healing of critical-size defects treated with bovine bone graft

Abstract

Objective To histomorphometrically analyze the effect of low-level laser therapy (LLLT) on bone formation process in surgically created critical-size defects (CSDs) treated with bovine bone graft (BBG) and its influence over particles' resorption of BBG. Methods A 10-mm diameter CSD was surgically created in the calvaria of 64 male rats, which were distributed into 4 experimental groups: the C group (control), only blood clot; the LLLT group, LLLT (GaAlAs, 660 nm) and blood clot; the BBG group, CSD filled with BBG; the BBG/LLLT group, LLLT and CSD filled with BBG. Animals were euthanized at either 30 or 60 days post-operation. A histological analysis was performed. Additionally, the percentage of newly formed bone area (NFBA) and remaining particles areas (RPA) of BBG were histometrically evaluated and data statistically analyzed. Results The LLLT (5.82 ± 2.05; 7.34 ± 1.01) group presented significantly greater NFBA when compared to the C group (1.61 ± 0.30; 5.59 ± 0.94) at 30 and 60 days post-operation (p < 0.05). The BBG/LLLT group (7.39 ± 1.45; 9.44 ± 2.36) presented significantly greater NFBA than the BBG group (3.85 ± 1.56; 8.02 ± 0.63) at 30 and 60 days postoperation (p < 0.05). There was no significant difference in the mean percentage of implanted material RPA between the BBG and the BBG/LLLT groups. Conclusions LLLT can improve bone formation process in CSD filled or not with BBG in rat calvaria, but it is not able to accelerate particles resorption of this material in the interior of bone defect.