Evaluation of resin adhesion to zirconia ceramic using some organosilanes

This study evaluated and compared the effect of three trialkoxysilane coupling agents on the bond strength of a Bis-GMA-based unfilled resin and a dimethacrylate-based resin composite luting cement to a zirconia ceramics (Procera AllZircon, Nobel Biocare, Göteborg, Sweden).

Six square-shaped zirconia specimens were used for each test group, a total of 72 specimens. The specimens in each group were all assigned to air-borne alumina particle abrasion followed by tribochemical silica-coating and silanization with 1 vol% solutions of 3-methacryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltrimethoxysilane, or 3-isocyanatopropyltriethoxysilane in an ethanol-water mixture. The sample stubs were made of a Bis-GMA/MMA/DMAEMA resin or a commercial resin composite luting cement (RelyX ARC, 3M ESPE, Seefeld, Germany). They were bonded to the conditioned and silanized silica-coated zirconia specimens using polyethylene molds. All specimens were tested at dry and thermo-cycled (6000, 5-55 degrees C, 30 s) conditions. The shear bond strength of resin stubs to zirconia was measured in a universal testing machine (cross-head speed 1 mm/min).

In dry conditions, the highest shear bond strength was 9.7 MPa (S.D. 3.3 MPa), and for thermo-cycled samples 7.4 MPa (S.D. 2.4 MPa) was obtained with RelyX ARC cement with 3-methacryloyloxypropyltrimethoxysilane. In general, thermo-cycling decreased the bond strengths significantly for the Bis-GMA resin (ANOVA, p < 0.005). The resin, cement and silanes differed significantly silanes (ANOVA, p < 0.005). All samples silanized with 3-isocyanatopropyltriethoxysilane de-bonded during thermo-cycling. De-bonding was dominantly due to adhesive failure.

Bonding of the experimental resin and commercial cement to silica-coated zirconia is effective with 3-methacryloyloxypropyltrimethoxysilane or 3-methacryloyloxypropyltrimethoxysilane, but not with 3-isocyanatopropyltriethoxysilane.