• Mutluay, Mustafa Murat
• Tezvergil-Mutluay, Arzu
• Tjäderhane, Leo
• Koistinen, Arto
• Stape, Thiago Henrique Scarabello
• Uurasjärvi, Emilia

Abstract

<p>Objective. Imperfect polymer formation as well as collagen's susceptibility to enzymatic-degradation increase the vulnerability of hybrid layers over time. This study investigated the effect of new dimethyl sulfoxide (DMSO)-containing pretreatments on long-term bond strength, hybrid layer quality, monomer conversion and collagen structure.</p><p>Methods. H3PO4-etched mid-coronal dentin surfaces from extracted human molars (n = 8) were randomly treated with aqueous and ethanolic DMSO solutions or following the ethanol-wet bonding technique. Dentin bonding was performed with a three-step etch-and-rinse adhesive. Resin-dentin beams (0.8 mm(2)) were stored in artificial saliva at 37 degrees C for 24 h and 2.5 years, submitted to microtensile bond strength testing at 0.5 mm/min and semi-quantitative SEM nanoleakage analysis (n = 8). Micro-Raman spectroscopy was used to determine the degree of conversion at different depths in the hybrid layer (n = 6). Changes in the apparent modulus of elasticity of demineralized collagen beams measuring 0.5 x 1.7 x 7 mm (n = 10) and loss of dry mass (n = 10) after 30 days were calculated via three-point bending and precision weighing, respectively.</p><p>Results. DMSO-containing pretreatments produced higher bond strengths, which did not change significantly over time presenting lower incidence of water-filled zones. Higher uniformity in monomer conversion across the hybrid layer occurred for all pretreatments. DMSO-induced collagen stiffening was reversible in water, but with lower peptide solubilization.</p><p>Significance. Improved polymer formation and higher stability of the collagen-structure can be attributed to DMSO's unique ability to simultaneously modify both biological and resin components within the hybrid layer. Pretreatments composed of DMSO/ethanol may be a viable-effective alternative to extend the longevity of resin-dentin bonds. (C) 2021 The Author(s). Published by Elsevier Inc. on behalf of The Academy of Dental Materials.</p>

Topics

• surface
• polymer
• scanning electron microscopy
• strength
• elasticity
• durability
• resin
• susceptibility
• Raman spectroscopy
• weighing