Effect of Low-level Laser (gaas, 904hm) for Bone Repair on Fractures in Rats.

OBJECTIVE To analyze the effects of low-level laser therapy (GaAs, 904 nm) for bone repair on tibial fractures in rats. METHODS Forty rats were divided into four groups of 10 animals: control group without fracture (CG); fracture group without treatment (EG II); fracture group treated with laser at 10 J/cm(2) (EG III); and fracture group treated with laser at 15 J/cm2 (EG IV). The fracture was produced surgically and the treatment lasted 45 days, done on alternate days. After treatment completion, the rats were sacrificed. The tibias were radiographed and subjected to mechanical three-point flexion tests in order to evaluate the maximum force (N) required to break them. RESULTS The observed maximum force values (N) were: control group (CG) of 51.5 N ± 7.9 N; EG II 17.2 N ± 7.8 N; EG III 16.6 N ± 12.1 N; and EG IV 30.3 N ± 7.8 N. There were statistically significant differences between the control group and the experimental groups and also between experimental group IV and the other experimental groups (II and III). Radiographs showed callus formation in all the fractured groups, thus indicating that they had undergone the normal tissue repair process. CONCLUSION EG IV, which underwent laser therapy with a dosage of 15 J/cm(2), showed the highest maximum force value (N) among the experimental groups, thus demonstrating the influence of higher laser dosage on bone repair.