Understanding in vivo response and mechanical property variation in MgO, SrO and SiO2 doped β-TCP

The aim of this work is to evaluate the influence of MgO, SrO and SiO2 doping on mechanical and biological properties of beta-tricalcium phosphate (beta-TCP) to achieve controlled resorption kinetics of beta-TCP system for maxillofacial and spinal fusion application. We prepared dense TCP compacts of four different compositions, i) pure beta-TCP, ii) beta-TCP with 1.0 wt.% MgO + 1.0 wt.% SrO, iii) beta-TCP with 1.0 wt.% SrO + 0.5 wt.% SiO2, and iv) beta-TCP with 1.0 wt.% MgO + 1.0 wt.%SrO+ 0.5 wt.% SiO2, by uniaxial pressing and sintering at 1250 degrees C. beta phase stability is observed at 1250 C sintering temperature due to MgO doping in beta-TCP. In vitro mineralization in simulated body fluid (SBF) for 16 weeks shows excellent apatite growth on undoped and doped samples. Strength degradation of TCP samples in SBF is significantly influenced by both dopant chemistry and amount of dopant. Compressive strengths for all samples show degradation in SBF over the 16 week time period with varying degradation kinetics. MgO/SrO/SiO2 doped sample shows no strength loss, while undoped TCP shows the maximum strength loss from 419 +/- 28 MPa to 158 +/- 28 MPa over the 16 week study. In case of MgO/SrO doped TCP, strength loss is slow and gradual. TCP doped with 1.0 wt.% MgO and 1.0 wt.% SrO shows excellent in vivo biocompatibility when tested in male Sprague-Dawley rats for 16 weeks. Histomorphology analysis reveals that MgO/SrO doped TCP promoted osteogenesis by excellent early stage bone remodeling as compared to undoped TCP. (C) 2011 Elsevier Inc. All rights reserved.