الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Several immediate dentin sealing (IDS) strategies have been proposed to improve bond strength of CAD/CAM indirect restoration to dentin surface. However, information regarding the durability and effect of such strategies using universal adhesive system on the bond strength is lacking.
Objectives: This study evaluated the effects of adhesive application timing and provisional phase on the shear bond strength (SBS) between dentin and CAD/CAM resin nanoceramics, and investigated the failure mode.
Methods: Thirty-two cylinders of (Lava Ultimate TM) were randomly divided into four groups (n= 8), each cemented to prepared flat dentin surfaces using Scotch Bond Universal and RelyX Ultimate resin cement. The single-visit approach, IDS1, involved immediate application of adhesive and cementation of the samples with no provisional phase, whereas the two-visit approach groups exhibited a provisional phase (two weeks), IDS2 application of the adhesive immediately before a provisional restoration, and IDS2+F reinforced this adhesive with a flowable composite. In the control group (DDS), the adhesive was applied after the provisional phase. Specimens were thermocycled, shear tests were performed, and failure modes were determined by stereo microscope and scanning electron microscope. Kruskal–Wallis and Mann–Whitney U tests were performed (p ≤ 0.05).
Results: The highest mean SBS was recorded in IDS1 (18.03 ±3.96 MPa), followed by IDS2 (16.12±5.41 MPa), and IDS2+F (15.69 ± 4.44 MPa). A significant association between the failure mode and study groups was found using the Monte Carlo test. The majority of adhesive failures with exposed dentinal tubules at the hybrid layer were noted in DDS, which was associated with the lowest SBS (12.18±5.39 MPa), and mixed failures predominated in all immediate dentin sealing (IDS) groups.
Conclusion: IDS with universal adhesives improve SBS, particularly in the single-visit approach, which has shown significantly better performance, whereas the provisional phase has a negative effect.
Clinical Relevance: Cementation of indirect restorations in a single visit using chair-side CAD/CAM technology not only improves patient satisfaction by avoiding traditional impression and eliminating cavity contamination risk by overcoming the provisional phase, but also increases the bond strength and longevity.
Keywords: Immediate dentin sealing (IDS), single visit approach, universal adhesives, resin nanoceramics, CAD/CAM restorations.