Resin Cement Bond Strength to Dark-Cured Universal Adhesives

Objectives: To assess Shear Bond Strength (SBS) of a new universal resin cement to five universal adhesives under total dark-cure whereas neither the adhesive nor the cement was light-cured.
Methods: Forty extracted sound teeth were embedded in acrylic and sectioned to expose the dentin surface. Dentin surfaces gradually finished with a 600 grit size sandpaper, followed by ultrasonic cleaning in distilled water for 10 minutes. Five universal adhesives (Scotchbond Universal, 3M; Prime and Bond Elect, Dentsply; FuturaBond Universal, VOCO; Adhese Universal, Ivoclar-Vivadent; and OptiBond Universal, Kerr) were applied on a moist dentin surface (n=8/group) by a single calibrated operator following manufacturers’ instructions except for the light-curing. Specimens were placed on a bonding jig (Ultradent) with a Teflon mold, which was filled with resin cement (Nexus Universal, Kerr) in a single increment, 2mm depth. Specimens were placed in dark incubator at 100% humidity, 37°C for 24 hours. SBS test was conducted using a universal testing machine (Instron, Canton, MA) at cross-head speed of 1 mm/min with a load cell of 1,000 lbs. ANOVA and Tukey pairwise comparison were used to identify the differences between groups at a 95% confidence level.
Results: Mean values are displayed in the Table. Groups connected with the same letter are not significantly different.
Conclusions: OptiBond Universal followed by FuturaBond Universal provided significantly higher shear bond strength than the rest of the universal adhesives in dark-cure mode. Optibond Universal and Nexus Universal can be used in total dark-cure mode where the application of light is not possible, such as metal restorations.