The Impact of Immediate Versus Delayed Dentin Sealing on the Microtensile Bond Strength of Ceramic Restorations

Introduction: While immediate dentin sealing enhances bond strength over delayed sealing, conflicting evidence exists regarding the efficacy of adjunctive techniques such as sandblasting and fiber reinforcement. This study aimed to compare the microtensile bond strength and failure modes of ceramic restorations bonded using immediate (IDS) versus delayed (DDS) dentin sealing methods. Methods: Twenty human third molars were disinfected and randomly divided into control (DDS), IDS۱ (with sandblasting), IDS۲ (without sandblasting), and IDS۳ (with fiber reinforcement) groups. After tooth preparation, the samples were stored in distilled water at ۳۷° C for ۷ days. Ceramic discs were treated with the ۹.۵% hydrofluoric acid and silane primer, then cemented to the prepared teeth. The samples were stored in distilled water at ۳۷° C for ۲۴ hours. Bar-shaped samples were sectioned, thermocycled, and stored for ۷۲ hours in distilled water at ۳۷° C before microtensile bond strength testing. Failure types were assessed using a stereomicroscope. Results: The highest mean bond strength was observed in the IDS۳ group (۲۴.۰۹ MPa), followed by IDS۲ (۲۱.۳۸ MPa), IDS۱ (۲۱.۰۸ MPa), and DDS (۱۶.۵۷ MPa). One-way analysis of variance (ANOVA) revealed a noticeable difference in bond strength between the groups (P<۰.۰۰۱). Tukey’s post hoc test demonstrated that all three IDS groups had significantly higher bond strengths compared to the DDS group, while no significant differences were found between the IDS groups. Qualitative assessments of failure types showed that failures were primarily adhesive between cement and bond, particularly in the DDS and IDS۱ groups. The IDS۳ group exhibited more mixed failures, indicating a stronger bond. Conclusion: Overall, immediate dentin sealing significantly improved bond strength compared to DDS, with no significant differences among the IDS techniques.