Behavior of Fibroblasts Irradiated with Different Lasers and Light-Emitting-Diode
Objectives: To assess the use of low-intensity laser and Light-Emitting Diode (LED) on the behavior of fibroblasts was evaluated comparatively. Methods: The viability of fibroblasts Balb/c 3T3 cultured under nutritional stress irradiated with red laser (660nm, 40mW), infrared laser (780nm, 50mW) and red LED (637 ± 15nm, 40mW) for 4 and 8 seconds was analyzed through the conversion of the tetrazolium salt (MTT) and neutral red assays. Statistical analysis was performed using the Kruskal-Wallis nonparametric test and ANOVA with a significance level of 5% (p = 0.05). This study received external funding of Fapemat protocol # 884/2007 Results: It was observed a trend of increase on the MTT conversion directly related to the irradiation time, however, not statistically significant. After 72 hours, the groups that showed higher MTT conversion were: infrared laser irradiated group, LED irradiated group, red laser irradiated group, positive control group (cells grown under ideal nutritional conditions without light exposure) and negative control group (cells grown under nutritional stress without light exposure). By the neutral red assay, though, after 72 hours the group that showed higher result was the positive control (grown under ideal nutritional conditions) followed by the group irradiated with infrared laser, the negative control group and groups irradiated with red laser and LED. Conclusion: By analyzing the results and considering the used parameters and phototherapy protocol, it is plausible to conclude that phototherapy with low-intensity laser and LED showed no toxicity at cellular level, even stimulating MTT conversion and neutral red uptake of fibroblasts cultured under nutritional stress, especially in the group irradiated with infrared laser (780nm, 50mW).