Acid-etching Effect Prior to Self-etching Primer Application on Bond Strength

Objectives: The purpose of this study was to evaluate acid-etching effects prior to the application of self-etching primer and also the effect of different primer application techniques on dentin shear bond strength. Methods: Fourty human third molar teeth were used. Dentin under the cervical regions was ground with 600-grit SiC-paper. Prepared teeth were randomly divided in four groups of 10. Tooth surface conditions were as follows: Group A: Clearfil Protect Primer (CPP) applied gently (inactive) + Clearfil Protect Bond (CPB) Group B: 38% phosphoric acid (PA) for 15 seconds, rinsed, dried + Clearfil Protect Primer (CPP) applied gently(inactive) + Clearfil Protect Bond (CPB) Group C: Clearfil Protect Primer (CPP) applied with agitation by micro-applicator brush (active) + Clearfil Protect Bond (CPB) Group D: 38% phosphoric acid (PA) for 15 seconds, rinsed, dried + Clearfil Protect Primer (CPP) applied with agitation by micro-applicator brush (active) + Clearfil Protect Bond (CPB). Clearfil ST composite resin was placed into a mold (2,5x2mm) in contact with the prepared surfaces and was cured. The specimens were embeded in acrylic resin for mechanical testing. Samples were stored in distilled water at 37°C for 24 hours. Shear bond strength test was performed with an Universal Testing Machine (Instron Model No:5569/2000) at a crosshead speed of 1 mm/min. Data were analysed using one-way analysis of variance (ANOVA). Comparison between pairs were made using Tukey HSD test at a level of significance of p<0.05. Results: The mean shear bond strength values (MPa) and standard deviations are as follows: Group A (35.95±8.34), Group B (23.98±6.94), Group C (35.03±3.25), Group D (30.64±6.73) Conclusions: Acid etching decreased the shear bond strength of the self-etching bonding systems to dentin. Active primer application increased the results only in acid-etched groups.