Low-level laser therapy with a pulsed infrared laser accelerates second-degree burn healing in rat: a clinical and microbiologic study

Abstract

Objective: This study was carried out to investigate the influence of pulsed-wave low-level laser therapy (LLLT) on the healing of a deep second-degree burn model in rat.

Background data: Review of literature indicates that LLLT has a biostimulatory effect on wound healing; however, no clear recommendation can yet be made.

Methods: Two deep second-degree burns were made in the skin of 67 rats. Rats were divided into four groups. In the first group (control), the proximal burn were received LLLT with shot down laser; in the second and third groups, proximal burns were treated with a 3,000-Hz pulsed infrared diode laser with 2.3 and 11.7 J/cm(2) energy densities, respectively. In the fourth group, the proximal burns were treated topically with 0.2% nitrofurazone. The distal burn of all groups was considered the control burn. The response to treatment was assessed both microbiologically and macroscopically.

Results: The incidence of Staphylococcus aureus decreased significantly in group 3 in comparison with group 1 on day 28 (χ(2) test, p = 0.05). Analysis of variance showed that LLLT with 11.7 J/cm (2) significantly increased the wound-closure rate at 2 weeks (0.915 ± 0.310) and 3 weeks (0.677 ± 0.397) after burning compared with placebo burns (1.413 ± 0.319; 1.116 ± 0.436, respectively) ANOVA-LSD test, p = 0.045 and p = 0.046 respectively. Independent sample t tests showed that LLLT with 11.7 J/cm (2) significantly increased the wound-closure rate at 4 weeks after burning (0.211 ± 0.146) compared with the control burns (0.707 ± 0.480) p = 0.039.

Conclusions: Pulsed LLLT with 11.7 J/cm(2)/890 nm of a deep second-degree burn model in rat significantly increased the rate of wound closure compared with control burns.