Effects of mechanical and chemical surface treatments on the resin-glass ceramic adhesion properties

Aim: Intraoral repair of fractured ceramic restorations using resin composite is practical for dental treatment. In the present study, we investigated whether differences in surface treatments for glass ceramic would affect resin adhesion.

Methods: Leucite-reinforced glass ceramic plates (IPS Empress Esthetic) were ground with 320-grit silicon carbide paper, cleaned using phosphoric acid, and then etched with hydrofluoric acid (IPS Ceramic Etching Gel) or left unetched, and silanized using silane coupling agent (RelyX Ceramic Primer) or kept unsilanized. Either conventional (Adper Scotchbond Multi-Purpose) or universal (Scotchbond Universal) adhesive was used to bond the resin composite to ceramic surfaces. Specimens were subjected to microshear test after 37°C water storage for 24 h, and fractured surfaces were examined. Ceramic surface hydrophobicity after treatments was verified with contact angle measurements. Data were analyzed using anova and Tukey's tests.

Results: Regardless of the adhesive tested, hydrofluoric acid-etched ceramics showed higher bond strengths. Ceramic primer application improved resin bonding, even in non-etched groups, and also influenced fractography (P < 0.001). Contact angles on ceramics treated with ceramic primer were higher than those treated with silane-containing universal adhesive (P < 0.001).

Conclusions: Mechanical and chemical retentions contribute to resin adhesion to glass ceramic. Universal adhesive seems to not function in the same manner as a silane coupling agent.