Use of nonhydrolyzed silane prior to the silane-containing universal adhesive application improves the repair bond strength of resin composite

Objective To compare the effect of hydrolyzed and nonhydrolyzed silanes prior to the silane-containing universal adhesive application on the repair bond strength between old and new resin composite. Material and methods Fifty-four blocks of nanohybrid resin composite (Z350 XT) were aged by water storage for six months. The aged specimen surfaces were wet-ground manually with 320-grit silicon carbide grinding paper and randomly assigned into six experimental groups according to surface treatment: silane-containing universal adhesive in the self-etch mode (Scotchbond Universal); nonhydrolyzed silane (Silane Coupling Agent) plus Scotchbond Universal; hydrolyzed silane (RelyX Ceramic Primer) plus Scotchbond Universal; self-etch adhesive system (Clearfil SE Bond); nonhydrolyzed silane plus Clearfil SE Bond; hydrolyzed silane plus Clearfil SE Bond. Blocks were repaired with the same composite. After 24 h of water storage, the blocks were sectioned and bonded sticks were submitted to microtensile bond strength test (μTBS). Two-way ANOVA and Tukey`s tests were used to analyze the μTBS means. Results The highest repair bond strength values were achieved when nonhydrolyzed silane was applied prior to the silane-containing universal adhesive system (p = 0.03). The previous silane application did not increase the repair bond strength when a two-step self-etch adhesive was used. Mixed/adhesive failures prevailed in all groups. Conclusion The use of a nonhydrolyzed silane prior to the silane-containing universal adhesive in the self-etch mode application improves the repair bond strength of old and new resin composite.