Physicochemical Properties of Novel Radiopaqued Dicalcium Silicate Cements

Objectives: The purpose of this study was to examine the effect of a Bi2O3 radiopacifier and the liquid-to-powder ratio (L/P) on the physicochemical properties of novel dicalcium silicate cements used in the endodontic treatment. Methods: The dicalcium silicate powder was prepared by using a sol-gel method. The setting time, diametral tensile strength (DTS), porosity, and composition of the cements containing 20% Bi2O3 were evaluated after mixing with water at different L/P ratios. Results: The Bi2O3-containing cement prepared with a greater L/P ratio of 0.5 mL/g had a setting time of 44 min, which was significantly higher (p < .05) than the corresponding cement (24 min) prepared with a lower L/P ratio of 0.4 mL/g. The DTS value (2.1 MPa) of the cement prepared with an L/P ratio of 0.4 mL/g was significantly higher (p < .05) than those of the cements with and without Bi2O3 with an L/P ratio of 0.5 mL/g, which were 1.8 and 1.7 MPa, respectively. The Bi2O3 addition and increased L/P ratio resulted in an increase in porosity from 38% up to 51%. The products of the hydration process were calcium silicate hydrate (C–S–H) at 2θ=29.4o and incompletely reacted inorganic component phases of dicalcium silicate at 2θ between 32-34o. The presence of Bi2O3 appreciably reduced the formation of C–S–H phase. Conclusion: The present cement prepared with an L/P ratio of 0.4 mL/g in terms of the setting time and strength has the potential to be a root-end filling material.