Basic Properties of Novel Bioactive Cement Based on Silica-Calcium Phosphate Composite and Carbonate Apatite

Abstract

Silica-calcium phosphate composite (SCPC) and carbonate apatite (CO3Ap) are resorbable bioactive materials with the ability to adapt to bone structure and to induce bone regeneration. Considering the similarity between bone and dental structure, where both are mainly composed of calcium deficient carbonate containing hydroxyapatite, we hypothesize that a SCPC-CO3Ap bone cement might also be favorable for the regeneration of dentin and pulp tissue. Therefore, in the present study we report on the effect of composition and structure of SCPC-CO3Ap cement on the morphology, setting and mechanical properties of the material. The novel bioceramics cement composed of vaterite, dicalcium phosphate anhydrous (DCPA) and SCPC. The powder cement ratio divided into 5 groups: group 1 (60% DCPA : 40% vaterite : 0% SCPC) as a control, group 2 (60% DCPA : 10% vaterite : 30% SCPC), group 3 (60% DCPA : 20% vaterite : 20% SCPC), group 4 (60% DCPA : 30% vaterite : 10% SCPC), and group 5 (60% DCPA : 0% vaterite : 40% SCPC). Each group was mixed by 1M Na2HPO4 aqueous solution at liquid to powder ratio of 0.5 and hardened at 37°C and 100 % of relative humidity for 72 hours. Set cement was examined by X-Ray diffraction (XRD), scanning electron microscopy (SEM) and the mechanical strength was evaluated by diametral tensile strength. XRD patterns revealed that the apatite formation was formed after 72 hours, however the intensity of apatite varied based on the SCPC content. The DTS evaluation indicated that group 3 has the highest mechanical strength compared to others. This was supported by SEM analysis of set cement showing more compact surface microstructure of group 2 and 3 compared to other different ratio and control group. The novel bioceramics cement was successfully made using vaterite, DCPA and SCPC. This new cement is currently being investigated for dental application to induce dentinogenesis.