An evaluation of CaF₂ doping tricalcium silicate as dental restorative materials

The aim of this study was to evaluate the suitability of CaF₂ doping tricalcium silicate (Ca₃SiO₅, C₃S) as dental restorative materials. The solid state reaction method was used to prepare CaF₂ doping C₃S (F-C₃S) using CaCO ₃, SiO₂ and CaF₂ as the starting materials. The in vitro bioactivity, the rate of heat evolution and the compressive strength were investigated. The in vitro bioactivity was examined by soaking the pastes in simulated body fluid (SBF). The FTIR and SEM results indicated the hydroxycarbonate apatite (HCA) layers of F-C₃S pastes and pure C ₃S pastes occurred after soaking for 1 day and 3 days, respectively. The difference in bioactivity was attributed to the formation of F-substituted apatite, which has a K_sp lower than HCA. As compared with the pure C₃S, the rate of heat evolution during the hydration of F-C ₃S was slower. This was avail to the dimensional stability of dental restorative materials. The pastes of F-C₃S had a lower early compressive strength in the early stage, but a higher compressive strength in the later stage. Our results indicated that F-C₃S would be bonded better to the teeth because of the earlier formation of HCA and the higher later compressive strength. F-C₃S may be a progressive candidate for dental restorative materials.