Effect of a two-step placement procedure on the dislocation resistance of a methacrylate resin-based root canal sealer: a proof of concept.

PURPOSE To investigate whether the placement of a methacrylate root canal sealer or a conventional epoxy root canal sealer in two steps increases their dislocation resistance when compared to a one-step placement procedure. MATERIALS AND METHODS Eighty single-rooted teeth were randomly allocated to 4 groups (n=20). All canals were instrumented to size 40, 0.06 taper and irrigated according to a standardized protocol. Root canal filling was conducted as follows: group 1: methacrylate sealer placed in two steps; group 2: methacrylate sealer placed in one step; group 3: epoxy sealer placed in two steps; group 4: epoxy sealer placed in one step. After setting, thin slices at different root levels were obtained and submitted to push-out testing. RESULTS were analyzed with non-parametric tests to compare the two-step procedures to their one-step counterparts. Failure modes were determined by stereomicroscopy. Random untested methacrylate sealer specimens were also examined with scanning electron microscopy. RESULTS At each root level, dislocation resistance was significantly higher for the two-step procedure than for the one-step procedure using the methacrylate sealer (p=0.003, p=0.005, p<0.001) but not the epoxy sealer (p=0.83, p=0.1, p=0.06). Among root levels, there were no significant differences in dislocation resistance in the methacrylate sealer two-step group, while all other groups showed differences. CONCLUSION A two-step placement procedure resulted in significantly higher dislocation resistance for the methacrylate sealer but not for the epoxy sealer.