• additional enamel etching;
  • enamel surface morphology;
  • one-step self-etch adhesives;
  • shear bond strength



To evaluate the effect of additional enamel etching on the shear bond strength of three self-etch adhesives.


Class II box type cavities were made on extracted human molars. Teeth were randomly divided into one control group of etch and rinse adhesive and three test groups of self-etch adhesives (Clearfil S3 Bond, Futurabond NR, Xeno V). The teeth in the control group (n = 10) were treated with Adper™ Single Bond 2. The three test groups were further divided into two subgroups (n = 10): (i) self-etch adhesive was applied as per the manufacturer's instructions; (ii) additional etching of enamel surfaces was done prior to the application of self-etch adhesives. All cavities were restored with Filtek Z250. After thermocycling, shear bond strength was evaluated using a Universal testing machine. Data were analyzed using anova independent sample's ‘t’ test and Dunnett's test. The failure modes were evaluated with a stereomicroscope at a magnification of 10×.


Additional phosphoric acid etching of the enamel surface prior to the application of the adhesive system significantly increased the shear bond strength of all the examined self-etch adhesives.


Additional phosphoric acid etching of enamel surface significantly improved the shear bond strength.