Effect of LLLT on autogenous bone grafts in the repair of critical size defects in the calvaria of immunosuppressed rats

The aim of this study was to evaluate the effects of low-level laser therapy (LLLT) on the bone repair of critical size defects (CSDs) filled with autogenous bone in the calvaria of immunosuppressed rats. A 5 mm-diameter CSD was created in the calvaria of 30 rats. The animals were divided into 5 groups (n = 6): Control (C) - the defect was filled with a blood clot; Dexamethasone (D) - dexamethasone treatment, and the defect was filled with a blood clot; Autogenous bone (AB) - dexamethasone treatment, and the defect was filled with autogenous bone; LLLT - dexamethasone treatment, and the defect received LLLT (660 nm; 35 mW; 24.7 J/cm2); and AB + LLLT - dexamethasone treatment, and the defect was filled with autogenous bone and received LLLT. All animals were euthanized at 30 postoperative days. Histometric and histological analyses were performed. The new bone area (NBA) was calculated as the percentage of the total area of the original defect. Data were analysed statistically (an analysis of variance and Tukey's test; P < 0.05). The AB + LLLT group showed the largest NBA of all groups (P < 0.05). The use of LLLT with AB effectively stimulated bone formation in CSDs in the calvaria of immunosuppressed rats.