Development of dual-setting calcium phosphate cement using absorbable polymer.

Calcium phosphate cements used as bone substitutes generally have low mechanical strength compared with the bones of the human body. To solve these needs, we have incorporated hydrogels in the manufacture of samples made of alpha-tricalcium phosphate (α-TCP) cement, developing a system of dual-setting cement. This study aimed to produce composite materials by combining α-TCP powder and hydrogels. The composites were prepared using the synthesized powder and four different formulations of hydrogels, using either poly(N-vinyl-2-pyrrolidone) or poly(N-vinyl-2-pyrrolidone-co-acrylic acid), with either azobisisobutyronitrile or ammonium persulfate as initiator. The properties of all composites were evaluated through measuring compressive strength and apparent density and through X-ray diffraction and scanning electron microscopy. The composites showed compressive strengths of around 24 MPa. Soaking the samples in simulated body fluid formed a layer of hydroxyapatite-like crystals on the surface of some samples, showing the bioactivity of the newly developed cements and their potential use as biomaterial.