To etch or not to etch, Part III: On the hydrophobic-rich content and fatigue strength of universal adhesives after long-term ageing.

Autor: Stape THS; Department of Restorative Dentistry and Cariology, Adhesive Dentistry Research Group, Institute of Dentistry, University of Turku, Turku, Finland; Turku University Hospital, TYKS, University of Turku, Turku, Finland. Electronic address: thiago.stape@utu.fi., Mutluay M; Department of Restorative Dentistry and Cariology, Adhesive Dentistry Research Group, Institute of Dentistry, University of Turku, Turku, Finland; Department of Prosthetic Dentistry, Institute of Dentistry, University of Eastern Finland, Kuopio, Finland., Tezvergil-Mutluay A; Department of Restorative Dentistry and Cariology, Adhesive Dentistry Research Group, Institute of Dentistry, University of Turku, Turku, Finland; Turku University Hospital, TYKS, University of Turku, Turku, Finland.
Jazyk: angličtina
Zdroj: Dental materials : official publication of the Academy of Dental Materials [Dent Mater] 2024 Jan; Vol. 40 (1), pp. 44-52. Date of Electronic Publication: 2023 Oct 25.
DOI: 10.1016/j.dental.2023.09.012
Abstrakt: Objectives: To examine whether dentin-etching extension and/or the hydrophobic-rich content of hybrid layers would affect fatigue strengths of a mild universal adhesive after long-term aging.
Methods: Twin-bonded resin-dentin interfaces were produced by etching sound midcoronal dentin beams with 32 % ortho-phosphoric acid for 15 s (OPA15s), 3 s (OPA3s) or 10 % meta-phosphoric acid for 15 s (MPA15s). Samples were bonded with a mild universal adhesive with or without additional coating using a solvent-free bisGMA-based bonding resin. Self-etch application served as control. Composite buildups were made with a nanofilled composite. Bar-shaped twin-bonded interfaces (0.9 × 0.9 × 12 mm) were aged for two years in artificial saliva at 37 ℃ and tested under 4-point flexure at quasi-static (n = 16) and cyclic loads (n = 35) until failure. The stress-life fatigue behavior was evaluated using the staircase method at 4 Hz. Crack initiation and fracture patterns were evaluated by SEM. Cyclic-loaded data was analyzed by Kruskal-Wallis on Ranks (α = 0.05).
Results: Significantly higher fatigue life distributions and higher endurance limits were observed for less aggressive etch-and-rinse protocols (OPA3s and MPA15s) after long-term ageing. Hydrophobic-rich coating produced 20-32 % higher endurance limits, prevented micrometer-sized porosities at bonded interfaces, reduced etching-associated variability and lowered crack formation. Significance Long-term hydrolysis produces detrimental effects on the fatigue strength of resin-dentin interfaces. The bond-promotion effect of less aggressive etch-and-rinse protocols and the creation of hybrid layers with higher hydrophobic-rich content are critical to extend the durability of mild universal adhesives. Therefore, current oversimplification trends in adhesive dentistry may limit resin-dentin bonding performance.
(Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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