Avaliação morfológica da capacidade osteocondutora da hidroxiapatita implantada na calota craniana de camundongos diabéticos

Abstract

Introduction: Diabetes mellitus is a worldwide public health problem that, if not treated adequately, can cause various diseases, including loss of bone mineral density as a characteristic manifestation of osteoporosis. In this condition, bone is more vulnerable to pathological fractures that can be treated by conventional clinical methods. However, depending on the severity and quantity of bone loss, implantation of biomaterial grafts such as hydroxyapatite is necessary. Clinical studies have demonstrated the biocompatibility and osteoconductive capacity of this material. Objectives: To evaluate the osteogenic capacity of hydroxyapatite implanted into bone defects experimentally induced in the skull of diabetic NOD mice. Methods: Fifteen NOD mice were divided into three groups: control (non-diabetic), 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 porous hydroxyapatite granules. The animals were sacrificed 4 weeks after surgery and samples were obtained for analysis. Stereology was used to quantify the volume of newly formed bone in the recipient area according to the principle of Delesse. Data were analyzed by ANOVA followed by the Tukey test (p<0.05). Results: Radiology showed good radiopacity of the hydroxyapatite. However, radiolucent spots were seen between the hydroxyapatite granules in the diabetic groups, indicating infiltration of connective tissue. Microscopy showed projection of newly formed bone from the margin of the bone defect toward the implant, a finding indicating good bone-implant interaction. The volume of newly formed bone was 46% in the control group and was significantly higher (p<0.05) than that observed in the diabetic group (14%) and diabetic group receiving insulin (17%). Thus, in the diabetic groups the recipient area contained a larger amount of connective tissue as demonstrated by radiology. In all groups, the defect was filled with partially mature (cortical arrangement) and partially immature bone (trabecular morphology and disorganized osteocytes). Conclusion: Osteogenesis guided by the properties of hydroxyapatite may even occur in bone suffering from the effects of diabetes, but the volume of newly formed is lower and the process is slower.