Self-Etching Primer Or Hydrofluoric Acid: Effects On the Bond Strength Stability of a Leucite-Based Glass-Ceramic

To evaluate the effect of a self-etching primer on the long-term bond strength stability between a leucite-based glass-ceramic and resin cement, compared to the conventional treatment involving hydrofluoric acid (HF) etching followed by silane application.

Blocks of a leucite-based glass-ceramic (IPS Empress CAD) were cut into plates and embedded in acrylic resin. Half of the specimens were treated with 5% HF for 60 s and silane application, and the other half was treated with a self-etching primer (Monobond Etch and Prime, MEP). Resin cement cylinders (n = 24) were built onto their surfaces, and the specimens of each group were divided into three subgroups according to the microshear bond strength (µSBS) testing time: baseline, after 10,000 thermocycles, or after 10,000 thermocycles followed by 180 days of immersion in water. Statistical analysis was performed with two-way analysis of variance and Tukey's tests. Complementary failure mode, contact angle, and scanning electron microscopy analyses were carried out.

MEP groups showed higher bond strength results than HF. HF-treated specimens exhibited a decrease in bond strength after thermocycling and water storage, while MEP-treated specimens maintained similar bond strength values across all aging conditions. Only cohesive failures within the ceramic were observed at baseline. After aging, most HF specimens exhibited adhesive failures. HF etching created more irregularities with apparent deeper defects on the ceramic surface compared to MEP. HF etching produced a lower contact angle between the ceramic surface and the water drop compared to the self-etching primer.

Applying the self-etching primer resulted in higher bond strength stability between leucite-based glass-ceramic and resin cement compared to conventional treatment.