One and Two-step-self-adhesives are as Effective as a Two-step-etch-and-rinse Adhesive

Objectives: VCU School of Dentistry uses microhybrid-resin bonded with a two-step-etch-and-rinse adhesive (Optibond Solo Plus, OBSP) after application of 2% chlorhexidine (CHX) to etched enamel and dentin. Nanohybrid composite-resin (Kalore) is being evaluated to replace the microhybrid. Objective: compare Kalore using current resin-bonding standard (Etch/CHX/OBSP) to one and two-step-self adhesives.
Methods: Caries free molars (n=10) were mounted in resin and occlusal surfaces reduced with diamond saws exposing only enamel. OBSP applied as follows: enamel etched (H₃PO₄, 10-s, rinsed), CHX applied (60-s light scrubbing action, air dried 10-s), adhesive applied (20-s scrubbing motion, solvent evaporated air 10-s), application repeated and photo-cured (20-s, 500mW/cm²). Optibond XRT (OBXRT) applied as follows: primer scrubed on enamel (20-s, air thinned 5-s), adhesive lighlty brushed on (15-s, air thinned 5-sec), photo-cured (10-s 500mW/cm²). Clearfil SE applied as follows: enamel selectively etched (H₃PO₄, 10-s, rinsed 10-s), primer applied (20-s, solvent evaporated), adhesive applied (10-s) and photo-cured (500mW/cm²). Clearfil 3 Bond Plus applied as follows: enamel selectively etched (H₃PO₄, 10-s, rinsed), adhesive applied (10-s, air thin 5-s), photo-cured (10-s, 500mW/cm²). Ultradent bonding jig was used to bond (photo-cured, 40-s, 500mW/cm²) cylinders of Kalore 2.38-mm in diameter and 2.0-mm in height to enamel. Specimens were stored (deionized water, 37°C, 24-hrs) prior to shear testing (Instron Universal Testing machine,1.0-mm chisel-shaped bar, crosshead speed 0.5mm/s). After enamel testing teeth were reduced with diamond saws exposing only dentin and protocols repeated for dentin bonding with the exception that dentin was etched only for OBSP. Data was analyzed with two-way ANOVA and Tukey's HSD (p<0.05).
Results: Clearfil SE-dentin bond was statistically stronger than Clearfil 3-dentin bond. No other comparisons were statistically different. See Table 1.
Conclusions: All tested adhesives were equivalent to the VCU's bonding protocol and may be substituted for OBSP when used with Kalore.