Evaluation of the bone repair in defects grafted with hydroxyapatite and collagen membrane combined with laser therapy in rats

摘要

Bone regeneration is the result of cellular events such as osteogenesis and neovascularization.nHowever, implantation of autogenous grafts may be necessary in cases of bone mass loss due tonhigh impact trauma. The disadvantages of the latter approach include morbidity of the donor area.nBiomaterials represent an alternative for bone restoration. The most widely used compounds arencollagen or hydroxyapatite membranes because of their biocompatibility and osteoconductivity.nLaser therapy has been applied in combination with these implants to accelerate bone regeneration.nThe objective of this study was to evaluate the effects of low-level laser therapy (LLLT) on thenhealing of rat left tibial bone defects filled with hydroxyapatite or collagen membrane. Twenty ratsnwere used. Surgical bone defects were created in the proximal third of the left tibia, and the animalsnwere divided into four groups according to treatment: animals receiving hydroxyapatite implantsn(group H), animals receiving collagen implants (group C), animals treated with hydroxyapatite plusnLLLT (group HL), and animals treated with collagen membrane plus LLLT (group CL). Thenanimals were sacrificed 8 weeks after surgery, and the bone samples were obtained for analysis.nHistomorphometrical methods were used for new bone quantification. Data were analyzed bynanalysis of variance (p<0.05). Histological analysis showed the formation of new bone in thenimplant area with cortical aspect in groups. Bone neoformation was also demonstrated onnradiographs as radiopacity of the hydroxyapatite granules and of the contour of the defects implantednwith the collagen membrane. However, no significant difference for new bone formation wasnobserved between the groups studied. The biomaterials used were presented good osteoconduction;nhowever, the laser therapy protocol used was not adequate to accelerate the osteogenic process in thenbone defect regeneration in the advanced bone healing process.