Application of Low Hydrolysis Polyurethane and Dual Curing Urethane-acrylate in Root Canal Filling Material
Date Issued
2008
Date
2008
Author(s)
Tsai, Chung-Ting
Abstract
The purpose of this study was to develop a novel polymer-based root canal obturation material. Thermal polyurethane (TPU) was synthesized from polycarbonate-type polyol, and zinc oxide (ZnO) was added into TPU as filler to form the ZnO/TPU composite. Results showed that polycarbonate-type polyurethane and zinc oxide composite materials have great potential in root canal filling materials. In mechanical properties, it is shown that tensile strength and modulus of the ZnO/TPU composites can both be higher than gutta-percha and Resilon. For thermal properties, ZnO/TPU composite has lower melting than gutta-percha and Resilon. For hydrolysis test, polycarbonate-type polyurethane shows obvious properties of low-hydrolysis, explained by lower weight loss percentage than polyester-type polyurethane. Thus, it is found that ZnO/TPU composite still requires further investigations for clinical applications.or the sealer resin part, visible-light photopolimerizable urethane-acrylate oligomer was synthesized and mixed with dilute monomer to form UA/TPGDA resin. The relative molecule weight, viscosities, bonding strength, interface between sealer and dentin were investigated in this research. Results indicate that the viscosity of UA/TPGDA resin can be altered by the TPGDA content. The photo-initiator for UA/TPGDA (7/3 by wt.) is the mixture of camphorquinone and ethyl 4-dimethylaminobenzoate (1/2 by wt.) with concentration 3 phr, and it includes AIBN, also with concentration 3 phr, which is used as a thermal-initiator. We anticipated that the dual-curing method will improve the curing depth of the present system, and results show that the curing depth is satisfactory for clinical application. In flow analysis test , urethane-acrylate has passed the lowest acceptable standard of ISO 6876. As for bonding strength, results show that bonding strength of the UA/TPGDA (7/3 by wt.) and polyester-type polyurethane which were used as sealer and cone is the highest of all other groups of sealer and cone. It is found that visible-light curable urethane-acrylate oligomer has great potential in the root canal filling material sealer.
Subjects
root canal obturation material
TPU
urethane-acrylate
hydrolysis
sealer
Type
thesis
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