Effect of two laser photobiomodulation application protocols on the viability of random skin flap in rats

Objective: to identify the best low intensity laser photobiomodulation application site to increase the viability of the cutaneous flap in rats. Methods: 18 male rats (Rattus norvegicus: var. Albinus, Rodentia Mammalia) were randomly distributed into 3 groups (n = 6). Group I (GI) was submitted to simulated laser photobiomodulation, group II (GII) was submitted to the laser photobiomodulation at three points in the flap cranial base, and group III (GIII) was submitted to laser photobiomodulation at twelve points distributed along the flap. All groups were irradiated with an Indium, Galium, Aluminum and Phosphorus diode laser (InGaAlP), 660 nm, with power of 50 mW, total energy of 12 J in continuous emission mode. The treatment started immediately after performing the cranial base random skin flap (dimension of 10X4 cm(2)) and reapplied every 24 hours, with a total of 5 applications. The animals were euthanized after the evaluation of the percentage of necrosis area and the material was collected for histological analysis on the 7th postoperative day. Results: GII animals presented a statistically significant decrease for the necrosis area when compared to the other groups, and a statistically significant increase in the quantification of collagen when compared to the control. We did not observe a statistical difference between the TGF beta and FGF expression in the different groups evaluated. Conclusion: the application of laser photobiomodulation at three points of the flap cranial base was more effective than at twelve points regarding the reduction of necrosis area.