Shear Bond Strength Between a Polyester-based Root Canal Filling Material and a Methacrylate-based Sealer with an Intermediate Layer of Fiber-reinforced Resin-based Material

Purpose: To investigate the effects of an interfacial fiber-reinforced resin-based material (FRRM) application and different light-curing modes on the bond strength of a thermoplastic synthetic polymer-based root canal filling material (Resilon) to a methacrylate-based sealer (Epiphany). Materials and Methods: One hundred Resilon disks were prepared and divided into two experimental groups: 1. application of FRRM (EverStick Net) on the Resilon surface, and 2. Resilon alone (control). Following subsequent application of the Epiphany sealer, the specimens were randomly assigned into 3 subgroups according to the curing method employed: 1. chemical curing, 2. quartz-tungsten-halogen (QTH) light, and 3. light-emitting diode (LED). The latter two groups were further subdivided to test the effects of two different polymerization modes for each light-curing unit. Cured specimens were subjected to shear bond strength testing and the failure modes were examined. The data were analyzed with three-way analysis of variance (ANOVA). Results: Regardless of the curing method tested, application of FRRM at the interface significantly increased the bond strength of Resilon to Epiphany (p 0.001). Bond strength values (MPa) were as follows (mean ± SD): 1. chemical curing with FRRM= 3.0 ± 0.4, without FRRM = 1.2 ± 0.3; 2. QTH: a) standard mode with FRRM = 8.6 ± 0.6, without FRRM = 5.5 ± 0.9; b) ramp mode with FRRM = 8.0 ± 1.0, without FRRM = 5.3 ± 1.4; 3. LED: a) standard mode with FRRM = 8.8 ± 1.1, without FRRM = 5.4 ± 1.0; b) exponential mode with FRRM = 8.5 ± 1.0, without FRRM = 4.6 ± 0.6. Although light curing of specimens significantly increased the bond strength of Resilon to Epiphany (p 0.001), the type of light-curing unit and different curing modes had no significant influence on bond strength (p = 0.852 and p = 0.776, respectively). Conclusion: The highest bond strength values were obtained when the FRRM was used at the interface and the sealer was light cured. Keywords: bond strength, Epiphany, fiber-reinforced resin-based material, light curing modes, Resilon