(293f) The Role of Magnesium Substitution On the Properties and in Vitro Bioactivity of Brushite Cements

The clinical need to effectively treat bone and craniomaxillofacial defects continues to be a challenge for surgeons. Autografts have problems such as donor site morbidity and limitations on use for large bone defects, while allografts have disadvantages such as the potential to provoke an undesired immune response and the risk of disease transmission. Among many synthetic bone substitutes, the osteoconductive, and in some cases osteoincudctive, properties of calcium phosphate cements (CPCs) have been utilized for bone tissue engineering and several formulations have already been commercialized. Compared to apatite forming CPCs, brushite CPCs are acidic, highly resorbable, mechanically weak, and set rapidly. In order to alleviate some of the problems of pure brushite cements, magnesium substituted brushite cements were synthesized and studied. A simple novel low temperature synthesis method was used to synthesize nano-sized magnesium substituted β-tricalcium phosphates (β-TCMPs). These nano-sized β-TCMPs were then used as CPC precursors by reacting with monocalcium phosphate monohydrate and sodium citrate. β-TCMPs were also reacted with monopotassium phosphate and cement setting and handling characteristics were studied. Detailed investigations were made on the crystalline phase and morphological evaluation of these cements with time. In vitro results showed that Mg-substitutions stabilized the pH within physiological conditions during static culture, and as a result improved proliferation as well as bioactivity of mouse osteoblasts (MC-3T3) on these brushite CPCs.