Adhesion Methods and Durability for Repair of Reinforced Feldspathic Ceramic

Objective: This study evaluated the adhesion durability of a resin composite to an alumina reinforced ceramic after 3 different surfaces treatments. Methods: Ceramic blocks (48) (Vitadur Alpha-VITA) (5x5x5mm) were made according to the manufacturer's recommendations. They were then randomly assigned to 3 groups considering the surface treatments (ST),namely, ST-1: Conditioning with hydrofluoric acid (HF) (9.6%) (1min) (Dentsplyl)+silane (ESPE-Sil), ST-2: Silica deposition with 30µm particles (CoJet-Sand)+silane, ST-3: Conditioning with Clearfil Repair Kit (Kuraray). After applying a thin layer of adhesive (Single Bond) on the ceramic surface, 3 layers of resin composite (W3D Master, Wilcos-Brazil), measuring each ±1.5 mm, were applied. The specimens were sectioned in the x and y axis, resulting in 6 specimens (sp) per ceramics block (adhesive area: ± 1mm²). The sps of each block were divided into 3 subgroups, according to the storage. Six experimental groups were obtained: Gr1: ST-1 + immediate testing [IT]; Gr2: ST-1 + thermocycling (6000 cycles, 5°-55°C) [TC]; Gr3: ST-2 + IT; Gr4: ST-2 + TC; Gr5: ST-3 + IT; Gr6: ST-3 + TC. Each sp was fixed with cyanoacrylate on adapted caliper and microtensile test was performed (1mm/min). The obtained data (MPa) were evaluated by 2-way ANOVA and Tukey (a=0.05). Results: The surface treatment demonstrated a significant effect on the bond results (P<0.0001). Thermocycling reduced the bond durability for all 3 surface treatments [Gr2: 12.1 ± 2.64c; Gr4: 14.5 ± 3.1b ; Gr6: 4.2 ± 2.1e ] when compared with immediate testing [Gr1: 19.8 ± 3.8a; Gr3: 12.4 ± 4.7c; Gr5: 9.9 ± 2.9d] (P<0.0001). Conclusion: Although the tested ceramic is reinforced with non- etchable alumina, after thermocycling, bond strength of the repair composite was the highest after HF acid etching and silanization.