Effect of Immediate Dentin Sealing and Surface Cleansing on Ceramic-to-Dentin Bond Strengths

Immediate dentin sealing (IDS) has been widely used to enhance adhesive bonding in indirect restorations. However, the influence of different bonding agents, temporary materials, and surface cleansing protocols on shear bond strength (SBS) remains unclear. Previous studies have reported conflicting results, and no consensus exists on the optimal combination of these factors for maximizing adhesive performance. This study aimed to evaluate how these variables affect SBS in IDS-based restorations.

Occlusal dentin surfaces of 80 human third molars were prepared and treated with either an etch-and-rinse adhesive (OptiBond FL, Kerr, Orange CA, USA) or a universal adhesive (G2 Bond, GC Corporation, Tokyo, Japan) to create an IDS layer. Specimens were then divided based on the type of temporary material used: eugenol-free cement (TempBond NE, Kerr) or resin-based material (Structur 2 SC, Voco GmbH, Cuxhafen, Germany). After 24-hour water storage, temporary materials were removed using either airborne aluminum oxide (Al2O3) particle abrasion or waterborne Al2O3 particle abrasion (AquaCare, Velopex, London, UK). Ceramic discs were cemented with resin cement, and SBS was measured using a universal testing machine. Failure modes were analyzed under a stereomicroscope, and structural changes on dentin surfaces were examined using scanning electron microscopy (SEM). Data were analyzed using three-way ANOVA with Bonferroni post hoc tests (α = 0.05).

Three-way ANOVA revealed a significant interaction among adhesive system, temporary material, and cleansing method (p < 0.001). Due to this interaction, only select pairwise comparisons were interpreted. The highest SBS was observed in the OptiBond FL-Structur 2 SC-AquaCare group, significantly higher than all other combinations (p < 0.05). AquaCare-treated groups consistently outperformed air-abraded groups in bond strength (p < 0.001). Within the air-abraded subgroup, G2 Bond Universal-Structur 2 SC yielded significantly higher SBS than G2-TempBond NE and OptiBond FL-Structur 2 SC (p < 0.05). Failure mode analysis showed a predominance of mixed failures across groups, with no significant differences among failure types (p = 0.729).

Cleansing method, adhesive system, and temporary material significantly and interactively influenced SBS in IDS-based restorations. AquaCare waterborne Al2O3 abrasion consistently yielded higher bond strengths than conventional Al2O3 air abrasion. The highest SBS was achieved with the combination of OptiBond FL-Structur 2 SC-AquaCare. These findings highlight the importance of optimizing all procedural steps to enhance bonding effectiveness.