Enamel deproteinization before acid etching and its effect on the shear bond strength--an in vitro study

This study was undertaken to assess the effect of enamel deproteinization with 5.25% sodium hypochlorite (NaOCl) before phosphoric acid (H3PO4) etching on the shear bond strength ofAdperTM Single Bond 2 adhesive and Filtek Z-350 XT composite resin.

Forty human sound permanent molars which were extracted for periodontal reasons were used in the experimental protocol as under: Group-A (20 teeth):-A 5X4 mm window of the enamel surface was etched with 37% H3PO4 gel for 15 seconds, washed with distilled water and air dried. A single coat of Adper Single Bond 2 adhesive was applied and photo polymerized for 20 seconds and Filtek Z-350 XT composite resin block of length 5 mm, width 4 mm and height 5mm respectively was built and photo polymerized in increments for 20 seconds each. Group-B (20 teeth):--Similarly the enamel surface was treated with 5.25% NaOCl for 60 seconds, washed with distilled water and then etched with 37% H3PO4 gel for 15 seconds, washed with distilled water and air dried. A single coat of Adper Single Bond 2 adhesive was applied and photo polymerized for 20 seconds and Filtek Z-350 XT composite resin block of length 5 mm, width 4 mm and height 5 mm respectively was built and photo polymerized in increments for 20 seconds each. The shear bond strength of all the samples were measured (in MPa) on Instron Mechanical Testing Machine.

The mean shear bond strength value for Group-A was 13.51 +/- 5.726 MPa and for Group-B being 15.06 +/- 6.220 MPa. No statistically significant difference in the shear bond strengths was observed between the two groups.

No significant effect of sodium hypochlorite enamel deproteinization on the shear bond strength of Adper Single Bond 2 adhesive and Filtek Z-350 XT composite resin before acid etching was observed in this study.