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

2012Study of the osteoconductive capacity of hydroxyapatite implanted into the femur of ovariectomized rats MICROSCOPY RESEARCH AND TECHNIQUE, MALDEN, v. 75, n. 2, pp. 133-137, FEB, 2012 http://www.producao.usp.br/handle/BDPI/42523 ABSTRACT Osteoporosis is a global public health that affects postmenopausal women due to the deficiency of estrogen, a hormone that plays an important role in the microarchitecture of bone tissue. Osteoporosis predisposes to pathological bone fracture that can be repaired by conventional methods. However, depending on the severity and quantity of bone loss, the use of autogenous grafts or biomaterials such as hydroxyapatite might be necessary. The latter has received increasing attention in the medical field because of its good biological properties such as osteoconductivity and biocompatibility with bone tissue. The objective of this study was to evaluate using histologic and radiographic analyses, the osteogenic capacity of hydroxyapatite implanted into the femur of rats with ovariectomy-induced osteoporosis. Eighteen rats were divided into three groups with six animals in each: group nonovariectomized, bilaterally ovariectomized not receiving estrogen replacement therapy, and bilaterally ovariectomized submitted to estrogen replacement therapy. Defects were created experimentally in the distal epiphysis of the femur with a surgical drill and filled with porous hydroxyapatite granules. The animals were sacrificed 8 weeks after surgery. The volume of newly formed bone in the implant area was quantified by morphometrical methods. The results were analyzed by ANOVA followed by the Tukey test (P < 0.05). The hydroxyapatite granules showed good radiopacity. Histological analysis revealed less quantity of newly formed bone in the ovariectomized group not submitted to hormone replacement therapy. In conclusion, bone neoformation can be expected even in bones compromised by estrogen deficiency, but the quantity and velocity of bone formation are lower. Microsc. Res. Tech. 75:133-137, 2012. V

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