Influences of different low level laser therapy wavelengths in rat tendon regeneration after tenotomy

Objective: The aim of this study was to compare the effect of the low level laser therapy in the organization of the collagen fibers with 3 J/cm² of dose in two wavelengths (670nm and 904nm) and in the combination of both on the tissue repair of the calcaneus tendon. Methods: We used 37 female Wistar rats divided in 5 groups which had been submitted to the total tenotomy. Group GA (n= 8) was submitted to the laser irradiation in λ= 904nm, GaAS, pulsated emission, peak power 15W and dose of 3J/ cm², group GB (n= 8) was submitted to laser irradiation λ= 670nm AlGaInP diode, continuous emission, power 30 mW and dose 3J/cm², group GAB (n= 8) was submitted to association of both of lasers and group GCL (n= 7) which the calcaneum tendon was submitted to placebo treatment. The group GP (n= 6) was a standard group without lesion and treatment. The animals received 12 sessions of lasertherapy and submitted to euthanasia on 14 th day after surgery. The tendons were submitted to histological procedure and were analyzed to evaluate the optic retardation (in nm) for the birefringence measurement. Results: The statistic analysis showed that the irradiated groups have higher values of optic retardation statistically significant than placebo group (p= 0,00001). It indicates that all the treated groups show better organization of collagen fibers in the longitudinal axis of the tendon, evidencing better quality in the tissue repair. The group GAB was that shown best results (p= 0,00001) when compared to another groups.