Effects of Various Desensitizing Agents on the Microtensile Bond Strength of a Hypersensitive Dentin Model Produced <i>in vitro</i> Using a One-step Self-etch System

Abstract

In the treatment of dentin hypersensitivity accompanying tooth substance defects such as wedge-shape defects, hypoesthesia can be achieved by applying a desensitizing agent before carrying out restoration using resin composite. However, almost no research has investigated the adhesion of resin to dentin coated with the latest desensitizing agents. Therefore, this study investigated the effects of various desensitizing agents on the adhesion of resin to dentin in combination with a 1-step self-etch system by using a hypersensitive dentin model in which the dentinal tubules were opened without etching and there was almost no smear layer on the intertubular dentin. Specimens with a #4000 polished dentin flat surface were ultrasonically cleaned for 60 min (15 min × 4 times). Then, the bond strength, failure modes, and micromorphology of surfaces coated with desensitizing agent to which resin was bonded immediately afterward and surfaces coated with desensitizing agent to which the resin was bonded after storage for 7 days in water were compared against a control to which no desensitizing agent was applied. The desensitizing agents used in this research did not promote adhesion of the resin immediately after application, but rather suppressed or completely obstructed it. Although deposits of microparticles and thin film material, which were observed immediately after application, tended to disappear after 7 days of storage in water, some of the desensitizing agents exhibited the same bond strength as the control, whereas other desensitizing agents did not show recovery of adhesion strength. Therefore, care is required when performing resin restoration immediately after application of a desensitizing agent, depending on the agent used, and caution must be exercised in the selection of desensitizing agents in the clinical setting.