Effect Of Different Adhesives And Surface Treatments Of CAD/CAM Resin Composite Blocks On Dentin Bond Strength

Abstract

This study was conducted to evaluate the effect of different adhesives and CAD/CAM surface treatment on the SBS of CAD/CAM resin composite to dentin. A total of 60 human molar teeth were used. Flat dentin surfaces were prepared, and teeth were vertically sectioned in the bucco-lingual directions into mesial and distal halves using low speed abrasive discs under copious water irrigation. Dentin specimens were divided into 12 groups (n=10/group) according to: 1- Type of adhesive, 4 groups (DC/E&R, DC/SE, SC/E&R, and SC/SE) and 2-CAD/CAM surface treatment, 3 groups (SB, SB/US, and SB/AE). CAD/CAM resin composite blocks were sectioned into 2mm x 2mmx 4mm rectangular rods using a slow speed disc equipped with a water-cooled diamond blade (Isomate), obtaining 120 rectangular rods. All CAD/CAM rods were sandblasted using 50μm aluminum oxide particles according to manufacture instructions and left without further treatment, ultrasonically cleaned in distilled water, or acid etched using 35% phosphoric acid. Adhesives were applied to dentin according to its manufacturer instructions. After each respective dentin and CAD/CAM rod surface treatment, rods were cemented to dentin using dual-cured resin cement according to manufacturers’ instructions. Specimens were stored in distilled water at room temperature for 48 hours before SBS testing. The SBS was run at a crosshead speed of 0.5 mm/min until failure. Statistical analysis was performed using Two-Way ANOVA/Tukey HSD test. The results of this study showed that the adhesive type, surface treatment, and their interactions (adhesive type x surface treatment) had significant effect on SBS (P=0.002, P0.0001, and P0.0001, respectively). Self-cured adhesive with etch-and-rinse mode showed higher significant SBS compared to dual-cured adhesive in etch-and-rinse mode (P<0.05). Sandblasting revealed the highest significant SBS (P<0.05) among the different surface treatments. Failure mode analysis showed that mixed failure mode was the predominate type of failure (59.2%).