A novel urethane acrylate-based root canal sealer with improved degree of conversion, cytotoxicity, bond strengths, solubility, and dimensional stability.

We have developed new urethane acrylate-based root canal sealers using polycarbonate (PC) as polyol and 2,2-azobis(2-methyl)butyronitrile (AMBN) as a thermal initiator. The purpose of this study was to compare the properties among a group of seven sealers: (1) polybutyleneadipate (PBA) with 2,2-azobis-isobutyronitrile (AIBN), (2) PBA-AMBN, (3) PC-AIBN, (4) PC-AMBN, (5) AH Plus (Dentsply DeTrey GmbH, Konstanz, Germany), (6) Epiphany (Pentron Clinical Technologies, Wallingford, CT), and (7) EndoREZ (Ultradent Products, Inc, South Jordan, UT). Attenuated total reflectance-Fourier transforming infrared spectroscopy was used to analyze the degree of conversion. Cytotoxicity was evaluated using MTT assay. In addition, push-out bond strength, solubility, and dimensional stability were investigated. Urethane acrylate-based root canal sealers behaved better than Epiphany and EndoREZ for the properties evaluated in this study. The PC-AMBN sealer exhibited the highest degree of conversion even in the apical third, and its cytotoxicity for nonsetting and aged specimens at 24 hours was comparable to AH Plus sealer. In addition, the PC-AMBN sealer with zinc oxide/thermoplastic polyurethane cones had a significantly higher bond strength than AH Plus with gutta percha. Solubility and dimensional changes of the PC-AMBN sealer conformed to the American National Standards Institute/American Dental Association (ANSI/ADA) standard 57. The PC-AMBN sealer has great potential for use in endodontic therapy.