[The effect of acid etching on bond strength of different self-adhesive resin cements to dentin]

To investigate the effect of acid etching on bond strength (μTBS) of self-adhesive resin cements (Unicem, G-Cem, Clearfil SA Cement, BisCem) to dentin.

Thirty-two human third molars without caries were used for the study. One fourth of the crowns were cut off, perpendicular to the long axis of the tooth with (Isomet) a low-speed saw, in order to expose the dentin surfaces of the sectioned sides. The sectioned dentin surfaces of the experimental groups were etched for 15 s. Subsequently, resin blocks were bonded to the dentin surfaces, with one of the four cements (Unicem, G-Cem, Clearfil SA Cement, BisCem). After being stored in water for 24 hours, all specimens were perpendicularly sectioned through the dentin-resin interfaces, prepared into beams about 1 mm×1 mm×8 mm for μTBS tests with micro-tensile tester. The micro-morphologies of the cement-dentin interfaces were assessed using scanning electron microscope. The data was analyzed using SPSS16.0 software package.

Without pre-treatment of acid etching, Unicem group (12.9±3.2) MPa, G-Cem group (11.7±2.6) MPa and Clearfil SA Cement group (10.9±2.3) MPa possessed a higher bond strength than BisCem group (6.8±2.4) MPa (P<0.05). Specimens with pre-treatment of acid etching showed a significantly lower dentin bond strength compared to those without pretreatment of acid etching (P<0.05) in self-adhesive cements (G-Cem, Clearfil SA CementUnicem, Unicem), but there was no significant difference in bond strength in BisCem group with or without acid etching.

With pretreatment of acid etching, the bond strength of self-adhesive resin cements to dentin decreases in G-Cem, Clearfil SA Cement and Unicem group, while there is no significant effect on the bond strength of BisCem group. Supported by Public Technology Applied Research Project of Science and Technology Bureau of Shaoxing City of Zhejiang Province (2012B70079).