| Summary: | 博士 === 國立臺灣大學 === 臨床牙醫學研究所 === 94 === Retrograde filling, perforation repair and vital pulp therapy are the common treatment strategies used in endodontics. The success of treatments depends on the adequate debridement of the pulp chamber and root canal system as well as the hermetic sealing obtained by an ideal restorative material. Calcium silicate bioceramics (CSCs), similar to the commercialized MTA in compositions, are potential materials for endodontic restorative treatments. It solidifies into a hard structure with high pH upon hydration. Recrystallization of CSCs may seal the pathways of communication between the canal system and its outer surface. CSCs also have the advantage of good handling properties. In this study, we developed a novel CSC for endodontic restorative treatments based on the CaO-SiOB2 Bsystem. We further investigated various material properties, including hydration behavior, surface bioactivity and perspectives for biocompatibility. Chapter 1 is dedicated to the development of a novel CSC and the investigations of its hydration mechanism. Utilizing SEM, XRD and FT/IR, we found the novel CSC, M811, and commercialized MTA shared the same hydration mechanism, in which CB3BS is the main contributor to the hydrated structure, catalyzing the production of the hydrates of CB3BA and CB4BAF, which in turn act as nucleation sites for CSH. Chapter 2 focused on the mechanism involved in the formation of bioactive apatite-like surfaces on CSCs in SBF. The apatite-like microstructure with Ca/P ratio of 1.57 was observed using SEM-EDS and the pattern of COB3B-for-POB4 Bapatite was identified by XRD and FT/IR. ICP-OES detected the loss of phosphorus in SBF. Based on these findings, the hypothesis that M811 may form the bioactive apatite-like layer on its surface in SBF was proved. Chapter 3 is to evaluate the biocompatibility for CSCs using MRPC-1 odontoblast-like cells. The results revealed that M811 demonstrated favorite cell adhesion and high cell viability as well as commercialized MTA. We also found that the C3S played the crucial role for the biocompatibility of CSCs. Notably, M811 revealed the similar hydration behavior to commercialized MTA which implies similar and comparable sealing capabilities in M811. Combine with the ability to form bioactive apatite-like layer on its surface in SBF, and its high biocompatibility, M811 is a potential material for restorative endodontic uses.
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