The effect of low-level laser on bone healing in critical size defects treated with or without autogenous bone graft: an experimental study in rat calvaria

Objective: The objective of this study was to evaluate the effect of low-level laser (LLL) on bone healing process in surgically created critical size defects in rat calvaria treated with or without autogenous bone graft (AB). Material and methods: The study was conducted on 40 male rats (Rattusnorvegicus, albinus, Wistar), weighing 250-300 g. For accomplishment of the experimental procedures, the rats were anesthetized with an intramuscular injection of xylazine (0.02 ml/kg) and ketamine hydrochloride (0.4 ml/kg). Acritical size defect with 5-mm diameter was created. The animals were divided into four groups: Group C (Control-filled with blood clot), Group LLL, Group AB (autogenous bone graft), Group AB + LLL (autogenous bone graft and LLL). The animals treated with LLL received applications of LLL at the infrared spectrum wavelength (lambda = 810 nm) and energy density of 6 J/cm(2) per point, 60 s per point, adding up to five points on the entire created defect. The animals were euthanized at 30 days postoperatively. After decalcification, each specimen was longitudinally divided into two blocks, exactly along the center of the original surgical defect, processed and embedded in paraffin. Longitudinal serial sections with 6-mu m thickness were made, initiating from the center of the original surgical defect. The sections were stained with hematoxylin and eosin (HE) for light microscopy analysis for histomorphometric analysis. Results: Group C presented smaller quantity of new bone formation than Groups LLL (P < 0.01), AB (P < 0.01), and AB + LLL (P < 0.01). Conclusions: Utilization of LLL favored the healing process in rat calvaria. The quantity of new bone formation with use of the LLL was similar to the autogenous bone