Bond Strengths of Self and Separate-Etching Adhesive Systems

Objective: The purpose of this study was to evaluate the resin-dentin interfacial morphology and shear bond strength of several new dentin bonding systems classified as etch &rinse /total etch (Prime & Bond NT (Dentsply/De Trey, USA), Admira Bond (VOCO, W Germany), Gluma One Bond (Heraeus Kulzer), Syntac Single Component (Ivoclar/Vivadent USA)), and self etching (Adper Prompt-l-Pop (3M ESPE, USA), I-Bond (Heraeus Kulzer, Germany)) on the deep dentin of primary teeth at the end of one year storage period. Methods: The occlusal surfaces of seventy-two recently extracted non-carious human primary molar teeth were abraded horizontally until a 1 mm residual dentine thickness was achieved. Composite resins were polymerised in clear PVC cylinders (1, 5mm Ø x 2 mm) on dentin specimens using one of six adhesive systems each representing a test group. All specimens were thermo cycled then stored in distilled water at 37°C for 365 days. The shear bond strength was calculated by dividing the peak failure loads by the bonding area. The data were statistically analysed using two-way ANOVA and Fisher’s PLSD test at the 99% level of confidence. The cross-sectioned resin dentin interfaces were evaluated with SEM. Results: The values of shear bond strengths for test groups were from higher to lower respectively as: Adper Prompt-L-Pop> Prime & Bond NT> I-Bond> Admira Bond> Gluma One Bond > Syntac Single Component. However, only the differences between Prompt-L-Pop vs. Syntac groups (U=0, p=0.000) and Prompt-L-Pop vs. Gluma groups (U=1, p=0.000) were statistically significant. SEM observation on sectioned surfaces of bonded specimens revealed seemingly equal length of resin tags in all groups. Conclusion: There were not great differences amongst shear bond strengths of self etch and etch and rinse dentin bonding systems in long term self etch agents were more capable to penetrate into primary teeth dentine tubules