Evaluation of Novel Adhesive System in Multi Etching Mode

Objectives: This study evaluated the bond strength of two-step self-etch adhesives to tooth structure in two-step self-etch (SE) and three-step etch-and-rinse (E&R) mode.
Methods: Human third molars (N=16) were divided into 2 groups: SE group; E&R group. Two adhesives: G-Premio Bond + BZF (GBZ, GC); Clearfil SE Bond 2 (CSB, Kuraray Noritake) were applied onto 320-grit SiC paper ground dentin surface using a split-tooth design (GBZ vs. CSB) and composite-resin (CR) was built up on the surface. After stored in water at 37°C for 24 hrs, the bonded teeth were sectioned into stick shape (1x1 mm width, 7-8 mm length). For each group, 15-23 sticks were subjected to micro tensile bond strength (μTBS) test at 1 mm/min. Data were analysed using two-way ANOVA followed by Tukey’s test (p<0.05). Area of failure mode distribution of de-bonded specimens were determined using SEM individually and total percentage of failure mode distribution was calculated as either: adhesive failure between CR and adhesive (AFCA); adhesive and dentin (AFAD); cohesive failure in the CR (CFC); adhesive (CFA); dentin (CFD).
Results: Mean (±SD) μTBS values were 73.14 (±14.05), 77.16 (±15.62), 70.70 (±12.73), and 65.88 (±7.24) MPa for SE-GBZ, SE-CSB, E&R-GBZ, and E&R-CSB respectively (Image1). SE showed significantly higher bond strength than E&R. Interaction effect was not significant, however SE-GBZ showed no significant difference with E&R-GBZ, and SE-CSB showed significantly higher bond strength than E&R-CSB. For GBZ, AFAD increased in E&R, for CSB, CFA increased in E&R (Image2).
Conclusions: Novel adhesive system showed high bond strength to tooth structure as well as conventional two-step self-etch adhesive and its bond strength was not affected by etch-and-rinse treatment.