| Summary: | 碩士 === 臺灣大學 === 高分子科學與工程學研究所 === 95 === The purpose of this study was to develop a novel polymer-based root canal obturation material. Thermal polyurethane (TPU) was synthesized from polyester-type polyol, and zinc oxide (ZnO) was added into TPU as filler to form the ZnO/TPU composite. The mechanical properties, thermal properties and specific heat of the ZnO/TPU composite were investigated and compared to gutta-percha and Resilon in this research. Results showed that tensile strength and modulus of the ZnO/TPU composites can both be higher than gutta-percha and Resilon. Enthalpy change of the ZnO/TPU composite during phase transition is near gutta-percha but is lower than Resilon. There is no significant difference in melting point among ZnO/TPU composite, gutta-percha and Resilon. Specific heat of the ZnO/TPU composite is near gutta-percha but is lower than Resilon. It is found that no matter in mechanical properties or thermal properties; ZnO/TPU composite has great potential in the root canal filling material.
For the sealer resin part, visible-light photopolimerizable urethane-acrylate oligomer was synthesized and mixed with dilute monomer to form UA/TPGDA resin. The mechanical properties, relative molecule weight, viscosities, conversions, polymerization shrinkage, bonding strength, interface between sealer and dentin and antibacterial properties UA/TPGDA resin were investigated in this research. Results indicate that the viscosity of UA/TPGDA resin can be altered by the TPGDA content. The photoinitiator for UA/TPGDA (7/3 by wt.) is the mixture of camphorquinone and ethyl 4-dimethylaminobenzoate (1/2 by wt.) with concentration 3 phr. As for polymerization shrinkage, the UA/TPGDA resin with no filler even expands 5.72×10-3 % after curing. Even the strain of the UA/TPGDA (7/3 by wt.) resin with 40% filler content after curing is only -7.26×10-2 %. As for bonding strength, results show that bonding strength of the UA/TPGDA (7/3 by wt.) with 40wt% HEMA-modified nano-SiO2 and Composite H3 which were used as sealer and cone is the highest of all other groups of sealer and cone. From SEM photographs, urethane-acrylate based sealer with 40% filler is able to flow into dentin tube and be cured in side the tube and be mixed well. Furthermore, UA/TPGDA resin becomes antibacterial because being blended with chlorhexidine. It is found that visible-light curable urethane-acrylate oligomer has great potential in the root canal filling material sealer.
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