Shear bond strength to sound and caries-affected dentin of sim-plified “etch-and-rinse” and “self-etch” adhesives and the hybrid layer micromorphology

Purpose: The purpose of this study was to compare shear bond strength (SBS) of currently available adhesive systems to sound dentin (SD) and caries-affected dentin (CAD) and elucidate the hybrid layer micromorphology. Materials and Methods: Sixty extracted human molars with coronal carious lesions formed the experimental sample while additional sixty extracted intact human molars (impacted third molars) served as controls. Identification of a carious-affected dentin was carried out using visual identification (North Carolina Dentin Sclerosis Scale). Teeth from both the experimental and the control sample were allocated to one of the following three groups: Adper Single Bond Plus/Filtek Supreme XT (ASB/FS) (3M ESPE), AdheSE One/Tetric EvoCeram (AO/TEC) (IvoclarVivadent), and Prime&Bond NT/CeramX Mono (PB/CXM) (Dentsply). Bonding procedures utilized in this work were in line with the manufacturers‟ instructions. The SBS was measured using a universal testing apparatus. Hybrid layer micromorphology was observed under scanning electron microscope (SEM). The SBS (in MPa), and hybrid layer thickness (in μm) were statistically analyzed using Ttest, Mann-Whitney U-test, ANOVA, and Holm‟s test. Results: Mean SBS±Standard Deviation were: ASB/FS to SD=10.56±3.49; ASB/FS to CAD=10.06±2.55; AO/TEC to SD=7.01±2.05; AO/TEC to CAD=6.73±1.66; PB/CXM to SD=9.01±2.47; PB/CXM to CAD=7.83±1.42. A statistically significant difference was found between the bonding strength of ASB/FS and AO/TEC to both SD and CAD, and between ASB/FS and PB/CXM to CAD. Hybrid layer thickness was statistically significantly greater for ASB/FS than for PB/CXM. For the ASB/FS system, a statistically significantly thicker hybrid layer was formed on CAD than on SD. No hybrid layer could be observed for AO/TEC.