Bond strength of epoxy resin and methacrylate-based sealers to dentin

Abstract

Purpose: To evaluate the bond strength of epoxy resinand methacrylate-based sealers to root dentin, using the “Material Testing Stage” (MTS) coupled to a micro-computed tomography ( CT) device, and to assess the percentage of misfit between the filling material and the root canal walls, by confocal laser microscopy. Methods and materials: Maxillary canine roots measuring 17mm were subjected to biomechanical preparation with nickel-titanium rotary instruments under constant irrigation with 1% sodium hypochlorite and final irrigation with 17% EDTA. Canals were filled by the lateral condensation technique with gutta-percha cones and the following sealers: AH Plus (n=10), Epiphany SE (n=10) and RealSeal XT (n=10). The roots were stored (100% humidity, 37 ◦C) for a period three times longer the setting time required for each sealer and then sectioned transversally to obtain two 2-mm-thick slices from each root third. One slice of each third was subjected to the push-out test using the MTS coupled to the SkyScan 1174 CT (50kV, 80mA) with 13 m isotropic resolution, 0.5mm Al filter and 360◦ rotation. After the initial scanning of the slice, the mechanical test was performed until material dislodgement occurred. A new scanning was performed using the same initial parameters. The 3D models obtained were used for qualitative evaluation of fillingmaterial dislodgement. The second slice of each root third was used to assess the percentage of misfit between the filling material and the root canal walls, using laser confocal microscopy with the aid of the OLS 4000 software and the FreeHand tool. The data were analyzed by ANOVA and Tukey’s test (p 0.05) among the evaluated root thirds (coronal, middle and apical). For AH Plus, the coronal (2.25± 0.40MPa) and middle (2.19± 0.62MPa) thirds differed significantly (p<0.05) from the apical third (0.80± 0.16MPa). Regarding the percentage of misfit between the filling material and the root canal walls, AH Plus presented the lowest means (11.14%± 4.03), differing significantly (p<0.05) from Epiphany SE (55.39%± 13.46) and RealSeal XT (62.50%± 6.72) sealers. Conclusion: The epoxy resin-based sealer (AH Plus) presented the highest bond strength to dentin, which resulted in the lowest percentage of misfit between the material and the root canal walls.