Abstract
Although adhesive resinous sealers for root canals have mainly been investigated by push-out bond testing, the microtensile bond strengths (μTBS) of these sealers to radicular dentin have not been systematically studied. To evaluate the bonding properties of four representative adhesive resinous sealers, the μTBS to radicular dentin was measured, debonded surfaces were analyzed by video-microscope, and the sealer-dentin interface was observed by SEM. Extracted single-rooted human teeth were used. After enlarging the root canal, the pulp chamber was irrigated with root canal irrigant and dried with paper points. Roots were then filled with Super-Bond RC-Sealer (Sun Medical), Epiphany® (Pentron, USA), Epiphany® SE™ (Pentron), or MetaSEAL™ (Parkell, USA) where an acrylic was point inserted. All specimens were kept moist at 37℃ for 2 weeks. The specimens were then ground into halves parallel to the long axis of the tooth to expose the point space, and sliced into 0.7mm thick sections. Slices were trimmed to create dumbbell-shaped specimens with a cross-sectional area at the bonding interface of 1.0mm2, and μTBS was measured at a cross-head speed of 1.0mm/min. The interface between the sealer and radicular dentin was observed by SEM, and the failure mode was examined by video-microscope. The results were as follows: 1. The μTBS of RC-Sealer and MetaSEAL™ was significantly higher than that of Epiphany® or Epiphany® SE™. 2. Microscopic evaluation of the failure mode indicated that failures in RC-Sealer and MetaSEAL™ were cohesive within the sealer itself, whereas in Epiphany® and Epiphany® SE™ failures were mostly interfacial. 3. In SEM observations of RC-Sealer and MetaSEAL™, gaps were not observed in any of the interfaces and the formation of resin tags and a hybrid layer was observed. In Epiphany® or Epiphany® SE™, resin tags were formed in part of the sealer-dentin interface. However, the hybrid layer was not observed in any of the radicular dentin walls, and gaps were occasionally observed.
