MSciD and PhD Post-graduate Program in Oral Science, Faculty of Odontology, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
MSciD Post-graduate Program in Dentistry, School of Dentistry, Meridional Faculty - IMED, Passo Fundo, Rio Grande do Sul, Brazil.
J Mech Behav Biomed Mater. 2019 Nov;99:198-205. doi: 10.1016/j.jmbbm.2019.07.022. Epub 2019 Jul 20.
This study evaluated and compared the effects of two glaze application methods (brush and spray) on the fatigue strength and surface characteristics (topography and roughness) of a translucent yttrium stabilized partially tetragonal zirconia polycrystal ceramic (Y-TZP) prior to and after grinding. Disc-shaped specimens of translucent Y-TZP (Vita YZ-HT; Vita-Zahnfabrik) were processed (ISO 6872-2015) and randomly allocated into 6 groups, according to the surface treatments performed on the tensile surface: Ctrl - as-sintered (no treatment); Gr - grinding with a diamond bur (181 μm-grit; #3101G); Br - glaze obtained from a powder-liquid mix and applied by brush (Vita Akzent; Vita Zahnfabrik); Sp - glaze application via spray (Vita Akzent Plus; Vita Zahnfabrik); Gr + Br and Gr + Sp - association of grinding + respective glaze method. Analyses of surface roughness (Ra and Rz), fatigue strength (staircase method), surface topography and fractography were carried out. The as-sintered condition had the smoothest surface, while grinding led to the rougher and more heterogeneous topography. Both glaze application methods showed a potential for topography evenness (smoothening effect), while the glaze spray method led to thinner layers of material, showing a limitation in reducing the roughness compared to the brush method. No deleterious effect on fatigue strength of the Y-TZP could be observed, as the glaze-spray application on the as-sintered surface showed the highest values. Fractography depicted two distinct fracture origin regions: from defects in the surface/sub-surface region for the Ctrl and Gr groups; and at the zirconia-glaze layer interface for Br, Sp, Gr + Br and Gr + Sp. The clinical relevance of this work is that the tested glaze application methods did not damage the fatigue strength of the tested Y-TZP.
本研究评估和比较了两种施釉方法（刷涂和喷涂）对预研磨和研磨后半透明钇稳定部分四方氧化锆多晶陶瓷（Y-TZP）的疲劳强度和表面特性（形貌和粗糙度）的影响。将半透明 Y-TZP（Vita YZ-HT；Vita-Zahnfabrik）的圆盘形试件按拉伸面的表面处理方式随机分组，共 6 组：Ctrl-烧结态（未处理）；Gr-金刚石车针研磨（181μm 粒度；#3101G）；Br-粉末-液体混合并通过刷涂获得的釉料（Vita Akzent；Vita Zahnfabrik）；Sp-通过喷涂进行釉料涂覆（Vita Akzent Plus；Vita Zahnfabrik）；Gr+Br 和 Gr+Sp-研磨+相应釉料方法的联合。对表面粗糙度（Ra 和 Rz）、疲劳强度（阶梯法）、表面形貌和断口形貌进行了分析。烧结态的表面最光滑，而研磨导致表面更粗糙且形貌更不均匀。两种施釉方法都具有使形貌均匀的潜力（光滑效果），而釉料喷涂方法导致材料层较薄，与刷涂方法相比，在降低粗糙度方面存在局限性。未观察到对 Y-TZP 疲劳强度的有害影响，因为在烧结态表面上进行的釉料喷涂应用表现出最高的强度值。断口形貌描绘了两个不同的断裂起源区域：对于 Ctrl 和 Gr 组，从表面/次表面区域的缺陷开始；对于 Br、Sp、Gr+Br 和 Gr+Sp 组，在氧化锆-釉层界面处开始。本研究的临床意义在于，所测试的施釉方法未损坏测试的 Y-TZP 的疲劳强度。
