MICRO SHEAR BOND STRENGTH OF UNIVERSAL DENTAL ADHESIVES TO DENTIN USING DIFFERENT ETCHING MODES (IN VITRO STUDY)

Abstract

Introduction:Patient demand for tooth colored restorations have made composites an important part of the restorative process. An important factor affecting the intraoral performance of composite restorations is bonding. Therefore, a strong bond at the tooth-restoration interface is necessary for long-term success of a composite restoration. Objectives: To compare the micro shear bond strength of a resin composite (Filtek Z250) to dentin using three universal adhesives in self-etching and total-etching modes and perform fractographic analysis using scanning electron microscope. Materials and methods:60 dentin specimens were used in this study. They were divided into two main groups (self-etch mode & total-etch mode). Each group was subdivided into three subgroups according to the bonding agent used (Tetric N bond universal, All bond universal and Single bond universal). Bonding of adhesives and composite buildups were done according to manufacturer’s instructions. All specimens were thermocycled for 500 cycles from 5 to 55°C. The micro shear bond strength was measured using universal testing machine. Specimens were further sectioned, gold sputtered and evaluated fractographically using scanning electron microscope (SEM). Data obtained were analyzed using F-test (ANOVA), two-way ANOVA and Spearman’s correlation tests. Results: In self-etch mode, the micro shear bond strength of the three tested adhesives didn’t show a significant difference. Meanwhile, etching significantly improved the micro shear bond strength of Single bond universal, while Tetric N bond universal and All bond universal showed no significant difference. Conclusions: An etching step prior to the application of the universal adhesives didn’t significantly affect their micro shear bond strength, except for Single bond universal.