Efeito do jateamento com um novo material a base de alumina revestido por diferentes concentrações de silica na adesão e nas propriedades mecânicas da Y-TZP

Abstract

This study is formatted into two parts: the aim of the first study was to evaluate a new approach (Sol-gel approach) to obtain an alternative material for air-abrasion (silica-coated with different concentrations aluminum oxide) on the bond strength with and without long-term aging between resin cement and a Y-TZP ceramic, considering different silica concentrations. Y-TZP ceramic specimens (7 × 6.3 × 2 mm3) were made and embedded in PVC molds using chemically activated acrylic resin. The specimens were allocated into 8 groups (n = 20) considering two factors: surface treatment (SiC: silica-coated aluminum oxide particles; AlOx: aluminum oxide particles; 7%Si: experimental material of silica-coated aluminum oxide particles (composed of 93% alumina and 7% silica); 20%Si experimental material of silica-coated aluminum oxide particles (composed of 80% alumina and 20% silica)) and aging (baseline: 24 hours at 37°C in a steam chamber; or aging with 90 days in a steam chamber + 12,000 cycles, 5-55ºC). The air-abrasion was executed for 10 sec at 1 cm distance from the devices tip with oscillatory movements at a pressure of 2.8 bar. The silane coupling agent Monobond Plus was applied on the ceramic surface and resin composite cylinders were made and cemented with Multilink Automix on Y-TZP ceramic and light cured. The shear test was performed using a wire loop (Ø = 0.5 mm). In baseline condition all groups presented similar bond strength values. After aging, the groups SiC and 7%Si remained similar to their counterpart baseline groups, while the groups AlOx and 20% presented a decrease on the bond strength values. A great amount of silica concentration of 20% was not capable to promote stable adhesion to resin cement after aging and it was similar to the AlOx group. However, 7%Si and SiC groups were similar and presented a better performance after aging. The second study evaluated the effect of the alternative material for air-abrasion on the superficial characteristics (topography and roughness), structural stability (t-m phase transformation) and fatigue performance (biaxial flexure fatigue strength) of Y-TZP ceramic, considering two different silica concentrations. Disc-shaped specimens were manufactured according to ISO 6872:2015 and allocated into 4 groups (n = 30) according to the surface treatment: SiC; AlOx; 7%Si; 20%Si. The air-abrasion was executed following the same protocol previously descripted on study 1. The biaxial flexural fatigue strength test was performed using the staircase method. The 7%Si group presented the highest fatigue strength values and it was similar to the SiC group, while the 20%Si group presented the worst fatigue behavior and it was similar to the AlOx group. The increase on silica-coating concentration did not promoted a gentle air-abrasion protocol, and 7%Si group promoted a higher fatigue performance compared to 20%Si.