Development of macropores in calcium carbonate body using novel carbonation method of calcium hydroxide/sodium chloride composite

Calcium carbonate is one of the bioceramics and has been used clinically as a bone substitute in dental and orthopedic surgery. Introduction of macropores into the bioceramics is highly recommended because those pores enable tissue ingrowth and accelerated osteointegration. We tried to prepare calcium carbonate body with macropores through the new carbonation method of calcium hydroxide/sodium chloride composite. Sodium chloride acted as a water-soluble porogen in developing macropores in calcium carbonate body and was removed completely by washing with distilled water after carbonation. We investigated effects of sodium chloride content and molding pressure on the porosity and the mechanical strength of the calcium carbonate body. Through this study, it was found that the porosity of body increased with the sodium chloride content in composite and was hardly affected by molding pressure. On the other hand, the mechanical strength was increased with the molding pressure and reduced with the porosity. In addition, the increase in content of sodium chloride caused the enlargement of hole size as well as the enhancement of extent of interconnection among pores through hole. Especially, the calcium carbonate body with over 90% porosity could be prepared when 90 wt.% sodium chloride was used under 10 MPa molding pressure. Its average pore and hole size were 177 and 80 mu m, respectively.