Effectiveness and acceleration of bone repair in critical-sized rat calvarial defects using low-level laser therapy

Background and Objective Tissue regeneration remains a challenge for orthopedic and craniomaxillofacial surgery to treat bone loss. The use of low-level laser therapy suggests a promise on this road with positive results for narrow defects. However, temporal and quantitative evaluations are required to understand the healing process of large injuries. The aim of this study was to investigate the repair of critical-size bone defects in rat calvaria using a GaAlAs laser. Study Design/Materials and Methods Bone defects (9 mm in diameter) were created on the skull of 30 Wistar rats separated in control or irradiated group. GaAlAs laser (λ = 830 nm, energy density = 2.5 J/cm2 and output power = 50 mW) was applied after surgery and six times more at 48 hours intervals. The animals were euthanized after 2, 4, and 8 weeks. Digital radiographs, descriptive histological and histomorphometric analyses were carried out. Results Radiographic analysis showed greater bone formation in the irradiated group than control at 8 weeks, covering 45% and 28% of the defect, respectively (P < 0.05). Histological analysis showed in the irradiated groups a higher amount of bone neoformation and greater maturity at 4 and 8 weeks. Histomorphometric analysis showed that the volume density of bone tissue at 4 weeks in the irradiated group was two times higher than the control (P < 0.01). Conclusion The biomodulation of low-level laser therapy using 830 nm wavelength light was effective in promoting bone healing in critical defects despite the unfavorable prognosis as well as it accelerated the maturation of bone tissue.