The Effect of Immediate Dentin Sealing Using Different Universal Adhesives on the Bond Strength of Pretreated Monolithic Zirconia to Dentin and Microscopic Morphological Alterations

Abstract

This study evaluated the effects of immediate dentin sealing (IDS) using different universal adhesives on microtensile bond strength (μTBS) of pretreated monolithic translucent tetragonal polycrystalline zirconia-based CAD/CAM restoration to dentin and microscopic morphological alterations. Mid-coronal dentin were obtained from 32 human molars and randomly allocated into 8 groups according to the presence/absence of IDS, universal adhesives for IDS (Single Bond Universal/SBU, Clearfil Quick Bond/CUQ, Optibond Universal/OBU) and zirconia surface pretreatments (tribochemical silica coating-30 μm CoJet particles/TSC, sandblasting-50 μm Al2O3/SB): Group TSC, Group TSC+SBU, Group TSC+CUQ, Group TSC+OBU, Group SB, Group SB+SBU, Group SB+CUQ, Group SB+OBU. CAD/CAM restorations (Lava Plus High Translucency Zirconia Disc) were produced, luted, and subjected to 10.000 thermocycles (5°C–55°C). Zirconia–dentin bars (2 × 2 × 8 mm) were subjected to μTBS test (n = 16). Surface morphology of zirconia and zirconia–dentin interfaces were analyzed under SEM (n = 1). Two-way ANOVA and Bonferroni tests were used for statistical analyses (p < 0.05). Regarding the presence of IDS, Group TSC + OBU showed statistically higher μTBS than Group TSC (p < 0.05). Comparing the IDS applied groups, Group TSC+OBU and Group SB+OBU showed statistically higher μTBS than Group TSC+CUQ and Group SB+CUQ, respectively (p < 0.05). According to the surface pretreatments, no significant differences in μTBS were found (p > 0.05). A thick, intact hybrid layer with long resin tags were observed for Group TSC+OBU and Group SB+OBU. After tribochemical silica coating or sandblasting pretreatments of monolithic zirconia, IDS procedure with Optibond Universal could affect the bond strength to dentin and morphological appearance, positively.