Physico-mechanical characteristics of tri-calcium silicate pastes as dentin substitute and interface analysis in class II cavities: effect of CaCl2 and SBF solutions.

The influence of using simulated body fluid (SBF) as a curing medium on some characteristics of pure single tri-calcium silicate (C₃S) bio-cement was investigated. CaCl₂ salt solution was used as an accelerating liquid for setting and hardening of C₃S pastes in comparison with distilled water (DW). Solid state reaction was applied to synthesis C₃S phase at elevated temperature followed by rapid cooling. The results showed that 10 wt.% CaCl₂ solution was the optimum concentration that showed the lowest setting time (106 min). C₃S pastes prepared with CaCl₂ solution have better physical and mechanical properties than those mixed with DW even after curing under SBF solution for the different curing ages. However, SBF solution has an adverse effect on the hydrated compound C-S-H that results in a little decrease in strength and hardness values. The elemental analysis emphasized the presence of apatite layer on the surface of the hardened C₃S paste. Scanning electron microscopy (SEM) photomicrographs and elemental analysis revealed reliable adaptation of the experimentally prepared C₃S paste to the tooth structure, in addition to its bioactivity makes it a consistent material to be used as dentin substitute.