Abstract
PURPOSE: To evaluate the effect of different surface treatments and adhesive cementation on the miniflexural strength (MFS) of monolithic zirconia. MATERIALS AND METHODS: Two-hundred and forty (240) sintered bars of translucent zirconia (Z(T)) and ultra-translucent zirconia (Z(UT)) were obtained (8 mm ×2 mm ×1 mm). The bars were divided into 16 groups (n = 15) according to the factors "Zirconia" (Z(T) and Z(UT)), "Cementation" (Cem) and "surface treatment" (Ctrl:Control, Al:Aluminum oxide/Al(2)O(3) 50 µm, Si:Silica/SiO(2) coated alumina particles oxide 30 µm, Gl:Glazing+hydrofluoric acid). Half of the bars received an adhesive layer application, followed by application of resin cement and light curing. The surface roughness was measured in non-cemented groups. All the bars were subjected to the MFS test (1.0 mm/min; 100 kgf). Scanning electron microscopy was used for qualitative analyses. MFS data (MPa) and roughness (µm) were statistically evaluated by three-way and two-way ANOVA respectively and Tukey's test (5%). RESULTS: The surface treatment and the interaction were significant for roughness. Glazing promoted less roughness compared to silicatization. Regarding MFS, only the zirconia and surface treatment factors were significant. For Z(T), the sandblasted groups had an increase in MFS and glazing reduced it. There was no difference between the groups without cementation for the Z(UT); however, Z(UT).Si/Cem, and Z(UT).Al/Cem obtained superior MFS among the cemented groups. CONCLUSIONS: Sandblasting increases the flexural strength for Z(T), while glaze application tends to reduce it. Applying resin cement increases the flexural strength of Z(UT) when associated with sandblasting. Sandblasting protocols promote greater surface roughness.