A Novel Polyurethane-Based Root Canal-Obturation Material and Urethane Acrylate-Based Root Canal Sealer - Part 1: Synthesis and Evaluation of Mechanical and Thermal Properties

Resilon (RealSeal; SybronEndo, Orange, CA) has been developed as an alternative to gutta percha, but its advantages over gutta percha remain controversial. In this study, we developed a novel zinc oxide/ thermoplastic polyurethane (ZnO/TPU) composite root canal-filling material and a visible-light curable urethane-acrylate/tripropylene glycol diacrylate (UA/TPGDA) root canal sealer. The mechanical and thermal properties of the ZnO/TPU composite were compared with those of gutta percha and Resilon. Results showed that the tensile strength and elastic modulus of the ZnO/TPU composite were markedly higher than those of gutta percha and Resilon. The melting points of all three materials were similar ; however, the enthalpy change and specific heat of ZnO/TPU (9.4 J/g, 0.7 J/g degrees C) were close to those of gutta percha (10.9 J/g, 0.7 J/g degrees C) but lower than those of Resilon (28.9 J/g, 1.3 J/g degrees C). The results indicate that ZnO/TPU composite exhibits better mechanical strength than Resilon, and its combination with UIA/TPFGDA sealer has excellent potential to be used as a root canal-filling material