Objectives

To assess the influence of a surface conditioner applied to pre-sintered yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) on the biaxial flexural strength and phase transformation.

Methods

Conditioner-coated specimens (12 mm diameter × 0.8 mm thickness) were prepared by application of a slurry conditioner using a brush on pre-sintered Y-TZP discs, followed by sandblasting with 50-μm Al₂O₃ after sintering (C-SB) or no further treatment (C-NT). The remaining conditioner-free specimens were subjected to sandblasting before sintering (NC-SB) or were maintained without treatment (NC-NT). Surface roughness measurements and scanning electron microscopy (SEM) in conjunction with energy dispersive X-ray spectroscopy (SEM-EDX) were performed for surface characterizations. The phase transformation of Y-TZP was identified by X-ray diffraction (XRD), and the biaxial flexural strength was measured using the piston-on-three-ball test according to ISO 6872:2015. The data were analyzed using nonparametric Kruskal–Wallis tests and Weibull distributions with the maximum likelihood estimation.

Results

Sandblasting resulted in significantly rougher surfaces, irrespective of conditioner application. Conditioner layers were observed on surfaces in the C-NT and C-SB specimens. Monoclinic contents were present in a very small amount in the C-SB specimens. Both median biaxial flexural and characteristic strengths of all specimens exceeded ISO 6872:2015 requirements (Class 5: >800 MPa), except the NC-SB specimens which showed significantly the lowest strength (p < 0.001). Although no statistical difference was observed in Weibull modulus among the specimens (p = 0.598), the NC-SB specimens showed the highest.

Significance

Surface conditioner application does not affect the biaxial flexural strength and phase stability of Y-TZP and can be considered practical for clinical use.

中文翻译：

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表面调节剂对氧化锆的预烧结对双轴弯曲强度和相变的影响

目标

评估应用于预烧结氧化钇稳定的四方氧化锆多晶体（Y-TZP）的表面调节剂对双轴弯曲强度和相变的影响。

方法

通过使用刷子在预烧结的Y-TZP圆盘上使用浆料调理剂，然后用50μm的Al ₂ O ₃喷砂，制备了调理剂涂层的样品（直径为12 mm×厚度为0.8 mm）。烧结后（C-SB）或不进行进一步处理（C-NT）。其余的不含调节剂的样品在烧结前进行喷砂处理（NC-SB），或未经处理保持原状（NC-NT）。进行表面粗糙度测量和扫描电子显微镜（SEM）结合能量色散X射线光谱（SEM-EDX）进行表面表征。通过X射线衍射（XRD）鉴定Y-TZP的相变，并根据ISO 6872：2015使用三球活塞试验测量双轴弯曲强度。使用非参数Kruskal-Wallis检验和具有最大似然估计的Weibull分布对数据进行了分析。

结果

不论使用何种调理剂，喷砂处理均会导致表面明显粗糙。在C-NT和C-SB样品的表面上观察到了调节剂层。C-SB标本中单斜晶含量很少。除NC-SB样品的强度最低（p  <0.001）外，所有样品的双轴弯曲强度和特征强度均超过了ISO 6872：2015的要求（5级：> 800 MPa ）。尽管样品之间的威布尔模量没有统计学差异（p  = 0.598），但NC-SB样品显示出最高。

意义

表面调节剂的应用不会影响Y-TZP的双轴弯曲强度和相稳定性，可以认为对临床使用是实用的。