Laser therapy in bone repair in rats: analysis of bone optical density

OBJECTIVE To investigate, by digital radiology, the bone regeneration process in rats submitted to femoral osteotomy and treated with low power laser therapy. METHODS Forty-five Wistar rats were subjected to transverse osteotomy of the right femur and divided randomly into three experimental groups (n = 15): animals not treated with laser therapy G (C), animals that received laser therapy with λ: 660nm G (660nm) and animals that received laser therapy with λ: 830nm G (830nm). Animals were sacrificed after 7, 14 and 21 days. The bone calluses were evaluated by digital X-ray at 65 kVp, 7mA and 0.032 s exposures. RESULTS The values obtained were submitted to variance analysis (ANOVA) followed by the Tukey-Kramer test. The significance level adopted was 5%. The groups G (C), G (660nm), and G (830nm) at the 7(th) day showed a significant bone development, with p <0.0116; the groups G (C), G (660nm), and G (830nm) at the 14(th) day showed values of p <0.0001; at the 21(st) day,a higher degree of bone repair were observed in group G (830nm), and G (660nm), with p <0.0169. CONCLUSION Based on the radiographic findings, G (830nm) showed more complete bone regeneration, as shown in the gray shades of the images. Level of Evidence II, Individual Study With Experimental Design.