Effect of dentin moisture and bonding strategies on micro-tensile bond strength using two chemically different universal adhesives

Abstract

To study the relevance of dentin moisture state on the micro-tensile bond strength (µTBS) and bonded interface morphology when using two universal adhesives with different compositions. Materials and Methods: Sixty-third molars randomly allocated into 12 groups based on adhesive types (Prime & Bond Universal [P&BU], Dentsply Sirona, New York, USA and Single Bond Universal [SBU], 3M ESPE, Neuss, Germany), adhesives application approach (etch and rinse or self-etch), and the amount of moisture found on surface of dentin (dry, wet & visible moist dentin surface). Thirty-six molars were divided into beams of composite and dentin with adhesive interface for µTBS (n=20) after restoration. Twenty-four molars were used to create specimens for scanning electron microscope evaluation of the bonded interface (n=2). For statistical analysis, three-way ANOVA was used, followed by a multiple comparison with Bonferroni adjustment. Results: In etch and rinse, P&BU had higher µTBS than SBU when the dentin surface was dry, SBU had higher µTBS when the dentin surface was wet. There were no differences between both adhesives on the moist dentin surface. In selfetch, SBU had higher µTBS than P&BU on the moist dentin surface, there were no significant differences between the two adhesives on dry and on wet dentin surfaces. For both adhesives, SEM images revealed better hybrid layer morphology and integrity with a greater number of resin tags and deeper penetration in etch and rinse approach than self-etch. Moist dentin surface developed better interface morphology than dry dentin surface, but wet dentin surface had the poorest hybrid layer quality with scarce resin tags in both adhesives. Conclusion: When dentin was moist or dry, universal adhesive systems demonstrated good adhesive performance. The response in wet dentin, on the other hand, is material composition dependent. Universal adhesives are better utilized in etch and rinse approach than the self-etch approach.