Potencial osteogênico de scaffold de hidroxiapatita substituída por sílica para o reparo de defeito ósseo crítico

Abstract

Introduction: Bone tissue has regenerative capacity, but extensive bone loss requires interventions to restore functionality and aesthetics in individuals affected by these injuries. In this sense, hydroxyapatite (HA) and silicon (Si) have been used to develop biomaterials designed to replace or regenerate bone tissue. HA is a ceramic that allows ionic substitutions in its crystalline structure to increase its bioactivity and regenerative capacity. When combined with oxygen (O₂), Si is a trace element that forms silicon dioxide (SiO₂), also known as silica. When Si is associated with other elements, it forms several types of silicates. When incorporated into the HA structure in the form of silicate anions, it improves the biological performance of the biomaterial, increasing its biocompatibility, osteoconductivity and bioactivity. Objective: To evaluate the biological behaviour and osteogenic potential of HA substituted by silica (SiHA) in the repair of critical bone defects. Material and Methods: The sample consisted of 24 animals, which were randomly distributed into two experimental groups, twelve animals in each of them, at the biological points of 15 and 45 days in the post implantation period: i) GHA - critical bone defect performed in rat calvaria with the implantation of HA scaffolds; ii) GSiHA - critical bone defect performed in rat calvaria with implantation of HA scaffolds with silica at a concentration of 5%. Results: Histological analysis demonstrated that, at all biological points, in both experimental groups, bone neoformation occurred between the biomaterials, more evident in GSiHA. Furthermore, the biomaterial filled the entire defect throughout the experiment. Both groups presented connective tissue, with differences in organisation. In the GHA group, the connective tissue was loose and edematous at 15 and 45 days, while in the GSiHA group, it remained thin, with disordered deposition of collagen fibres throughout the experiment. Chronic granulomatous inflammation was also observed at 15 and 45 days, more discreet at 45 days and accompanied by angiogenesis. Conclusion: The biomaterials, HA and SiHA, proved biocompatible, osteoconductive and bioactive, with osteogenic potential more evident in SiHA.