Efeito da laserterapia de baixa potência no reparo ósseo em ratos com diabetes mellitus tipo 1

Abstract

Low-level laser therapy is a highly concentrated non-ionizing radiation that has been used for therapeutic purposes. The present study evaluated the effect of low-level laser therapy on the bone repair of diabetic rats. Five animals were subject to type 1 diabetes mellitus T1DM induction and the other five animals remained healthy. After 4 weeks, it was created bone defects in the femurs. Left femurs received laser therapy and the right femur received no treatment. Seven days after surgery, animals were euthanized, the femurs were removed and divided into 4 groups (n=5), as follows: Healthy (right femur); Healthy+Laser (left femur subject to Laser therapy); Diabetic (right femur); Diabetic+Laser (left femur subject to Laser therapy). The femur was analyzed by micro-computerized tomography and by qualitative histological analysis. In the Micro-CT analyses, diabetic groups showed lower values of BV/TV, Tb.Th, Tb.N, and Conn.Dn than non-diabetic animals (p<0.05). However, there was increase BS/BV, Tb.Sp and SMI values in diabetic groups compared to non-diabetic groups (p<0.05). The Diabetic+Laser showed increase Tb.Sp and decrease Conn.Dn compared to Diabetic group (p<0.05). In histological analyses, all groups showed primary bone tissue in defect area. Healthy group presented more residual clot and granulation tissue compared to the Healthy+Laser. In the healthy groups, the neoformation bone tissue presented thicker trabeculae in relation to the diabetic groups. In Diabetic group, large areas of clot and granulation tissue were observed, as well as few trabeculae in relation to the other groups. In the Healthy+Laser group, there was less clot extension and amount of granulation tissue compared to Diabetic. The bone repair of Diabetic+Laser was apparently similar to Healthy group. The results showed that diabetes slowed the bone repair process and low power laser therapy was an important treatment to minimize the inflammatory process in all groups. And although it did not alter the bone volume, LTBP interfered in the structural morphology of the newly formed bone tissue in the healthy and diabetic groups. Key words: Diabetes mellitus, Laser, Bone repair, Computerized microtomography.