Influence of low-level laser therapy on the healing process of autogenous bone block grafts in the jaws of systemically nicotine-modified rats: A histomorphometric study

Objective To analyze the influence of low-level laser therapy (LLLT) on the bone healing process of autogenous bone block grafts installed in nicotine systemically modified rats. Methods Seventy-two rats (Wistar) were randomly assigned into 4 groups (n = 18). SS-BG: saline application + bone graft. SS-BG/LLLT: saline application + bone graft + LLLT. NIC-BG: nicotine application + bone graft. NIC-BG/LLLT: nicotine application + bone graft + LLLT. After 30 days of application of solutions, all animals received autogenous bone block graft in the jaw, with the donation from the parietal bone's calvarial area. Treatment with LLLT was in bed-graft interface, after accommodation of the graft. The animals in each group were sacrificed at 7, 14, and 28 days after graft surgery. Results The histologic analyses of NIC-BG group depicted a delay of osteogenic activity in the recipient bed-graft interface and the irradiation of tissue with LLLT provided better bone healing. The histometric analysis revealed that SS-BG/LLLT and NIC-BG/LLLT groups showed increased bone formation compared to BG-SS and NIC-BG groups, after 14 days (SS-BG 24.94% ± 13.06% versus SS-BG/LLLT 27.53% ± 19.07% and NIC-BG 14.27% ± 2.22% versus NIC-BG/LLLT 24.37% ± 11.93%) and 28 days (SS-BG 50.31% ± 2.69% versus SS-BG/LLLT 58 19% ± 12.32% and NIC-BG 36.89% ± 8.40% versus NIC-BG/LLLT 45.81% ± 6.03%). Conclusion Nicotine harms bone formation in the bed-graft interface and LLLT action can mitigate this.