Estudo ex vivo da cerâmica bifásica composta de hidroxiapatita- beta fosfato tricálcio (ha - ?-tcp) e pentóxido de nióbio (nb2o5) como biomaterial empregado para o reparo ósseo em defeitos de calvária

Abstract

Biomaterials, of natural or synthetic origin, composed of one or an association of two or more substances, have been increasingly used for the purpose of aiding in the repair or replacement of bone. The aim of this study was to evaluate ex vivo biocompatibility, bioactivity and osteoconductive activity of a composite consisting of hydroxyapatite- ß-tricalcium phosphate and niobium pentoxide in the repair of critical size defects in the calvaria of rats. Calvarial defects of 8 mm diameter were made in male Wistar rats. In the animals of the experimental group, the defects were filled with a tablet comprising the composite (HA ß-NbO) and in the control group, they were filled with a tablet of a biphasic ceramic composed by pure hydroxyapatite and ß-tricalcium phosphate (HA ß). Prior to implantation, the physico-chemical properties of the tablets were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and have been tested for microhardness. The animals were killed 7, 15, 30, 45 and 60 days after surgery. Samples of the skull were collected and processed for paraffin inclusion and then stained with H&E and Azan for histopathological study or SEM. Results indicated that both materials showed micropores. After sintering, the composite showed three distinct crystalline phases, with a predominance of ß-tricalcium phosphate (ß-TCP) (47.43%), and Vickers microhardness 66% higher when compared to HA ß. The tablets of the composite remained more securely clicked into the defects after all the observation periods. They also presented biocompatibility, bioactivity and osteoconductivity activity similar to that of HA ß. There was no development of fibrosis nor inflammatory reaction. We conclude that the composite has biocompatibility, bioactivity and osteoconductive activity similar to that of hydroxyapatite, having a chemical composition with greater amount of ß-TCP and higher microhardness.