Effect of Hydroxyapatite Bioceramic Bodies on Subcutaneous Soft Tissue Reaction of Laboratory Rats

Abstract

Hydroxyapatite (HA) is widely used in bioceramic materials for bone grafting. HA scaffolds were synthesized using solid-state reaction method. Scaffolds were prepared by milling the elements of CaCO3 and NH4H2PO4 powders. The obtained powder was pressed with uniaxial pressing into a disc shape with the dimension of 4 mm in thickness and 16.5 mm in diameter under pressures 3 MPa and then sintering the samples at difference temperatures from 1100°C to 1300°C for 3 hours. This research aimed to produce phase HA scaffolds in order to find out the effects of sintering temperature on phase contents, density, porosity, hardness and bending strength, and to use optimized condition samples study with laboratory rats’ soft tissue to evaluate the soft tissue response to the samples. Thirty-two healthy in adults’ on non-gender-specific of Wistar rats were used in this study. Optimized, sintered samples were cut and lathed into a cylindrical shape. Sixty-four samples of optimized condition were implanted and left in subcutaneous tissue for 3, 7, 14, 21, 30, 45, 90 and 180 days. XRD, XRF, Archimedes technique, Vickers hardness and bending strength, as well as light microscopy, were used for analysis. The results of optimized condition have shown the bodies of sintered sample at 1300 °C for 3 hours had the highest content of 91.02 % HA phase, and the remaining phases of 4.51 % b-TCP and 4.47 % CaO, its bulk density and strength increased with increasing temperature, the highest bulk density of 2.006 ± 0.033 g/cm3, hardness of 30.02 ± 3.23 HV, bending strength of 9.07 ± 1.15 MPa. Sample reactions to soft tissues at 180 days were mild inflammatory cells, an absence of cellular infiltration, a presence of calcification, and absence of displacement of ceramic components into surrounding host tissue. Our results concluded that the samples were nontoxic to subcutaneous tissue and biocompatibility