Diabetes mellitus can cause various diseases, including loss of bone mineral density as a characteristic manifestation of osteoporosis. In this condition, bone is more vulnerable to pathologic fractures that can be treated by implantation of biomaterial grafts. The aim of this study was to evaluate the osteogenic capacity of hydroxyapatite implanted into bone defects in the skull of nonobese diabetic mice. Fifteen nonobese diabetic mice were divided into 3 groups: control (nondiabetic), spontaneously diabetic, and spontaneously diabetic receiving insulin replacement applied subcutaneously into the dorsum. Defects were created experimentally in the skull with a surgical bur and filled with hydroxyapatite granules. The animals were killed 4 weeks after surgery, and samples were obtained for analysis. Quantitative methods were used for measurement of the new bone formation. Data were analyzed by analysis of variance followed by the Tukey test (P < 0.05). Radiographic results showed good radiopacity of the hydroxyapatite; however, radiolucent spots were seen between the hydroxyapatite granules in the diabetic groups, indicating infiltration of connective tissue. Microscopic results showed projections of newly formed bone from the margin of bone defect toward the implant. The quantity of newly formed bone was significantly higher (P < 0.05) than that observed in the diabetic groups. The recipient area of diabetic groups contained a larger amount of connective tissue as demonstrated by radiographic analyses. In conclusion, the osteogenesis guided by the properties of hydroxyapatite may even occur in bone suffering from the effects of diabetes, but the quantity of newly formed bone is lower, and the process is slower.

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 &lt; 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.

Polymeric biomaterials composed of extracellular matrix components possess osteoconductive capacity that is essential for bone healing. The presence of collagen and the ability to undergo physicochemical modifications render these materials a suitable alternative in bone regenerative therapies. The objective of this study was to evaluate the osteogenic capacity of collagen-based matrices (native and anionic after alkaline hydrolysis) made from bovine intestinal serosa (MBIS). Twenty-five animals underwent surgery to create a cranial defect to be filled with native and anionic collagen matrixes, mmineralized and non mineralized. The animals were killed painlessly 6 weeks after surgery and samples of the wound area were submitted to routine histology and morphometric analysis. In the surgical area there was new bone formation projecting from the margins to the center of the defect. More marked bone neoformation occurred in the anionic matrices groups in such a way that permitted union of the opposite margins of the bone defect. The newly formed bone matrix exhibited good optical density of type I collagen fibers. Immunoexpression of osteocalcin by osteocytes was observed in the newly formed bone. Morphometric analysis showed a greater bone volume in the groups receiving the anionic matrices compared to the native membranes. Mineralization of the biomaterial did not increase its osteoregenerative capacity. In conclusion, the anionic matrix exhibits osteoregenerative capacity and is suitable for bone reconstruction therapies.

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