Dose and Wavelength of Laser Light Have Influence on the Repair of Cutaneous Wounds

Abstract

Objective: The objective of the present study was to compare histologically the effect of GaAlAs (λ 830 nm, ϕ ∼ 2 mm², 35 mW) and InGaAlP (λ 685 nm, ϕ ∼ 2 mm², 35 mW) lasers, alone or in association with doses of 20 or 50 J/cm² on cutaneous wounds in the dorsum of the Wistar rat. Background Data: The healing time of surgical wounds is of extreme importance and it is usually associated with a post-operative period free of infection and with less pain and inflammation. Materials and Methods: Sixty Wistar rats were divided into seven groups: Group I - control (non-irradiated); Group II - λ 685 nm, 20 J/cm²; Group III - λ 830 nm, 20 J/cm²; Group IV - λ 685 nm and λ 830 nm, 20 J/cm²; Group V- λ 685 nm, 50 J/cm²); Group VI - λ 830 nm, 50 J/cm²; and Group VII - λ 685 nm and 830 nm, 50 J/cm². The animals were sacrificed 3, 5, and 7 days after surgery. Results: Light microscopic analysis using H&E and Picrosírius stains showed that, at the end of the experimental period, irradiated subjects showed increased collagen production and organization when compared to non-irradiated controls. Inflammation was still present in all groups at this time. Conclusion: Group IV (λ 830 nm and λ 685 nm, 20 J/cm²) presented better results at the end of the experimental period. It is concluded that low-level light therapy (LLLT) can have a positive biomodulatory effect on the repair of cutaneous wounds.