2016 Volume 57 Issue 12 Pages 2002-2007
Porous materials show low Young's moduli and excellent bonding to living bone. However, the strength of such materials is often insufficient in the initial stage of implantation. Thus, the objective of this study was to increase the strength of porous titanium by filling the pores with polyglycolide (PGA), a biodegradable plastic. PGA powder was prepared via the thermal decomposition of sodium chloroacetate at 433 K. The PGA was then introduced into the pores of porous Ti (porosity: 60%) using two methods: (i) centrifugal packing and heating and (ii) heat injection. In the latter method, almost all pores were filled by PGA; the filling fraction was measured to be 65–85% regardless of the injection temperature. When the pores in the porous Ti were filled with PGA, the compressive strength increased drastically from 40 to 100 MPa. The increased strength is comparable to that of cortical bone. In addition, the strength increased with increasing injection temperature. In an animal test, unfavourable autopsy findings, such as suppuration, bleeding, and hyperplasia of the connective tissue, could not be confirmed in rats and no bone was observed in the pores of the Ti–PGA composite. Decomposition of PGA lowered the surrounding pH, it was found to inhibit bone formation in the pores of the porous Ti. It is important to control the decomposition rate of PGA.