Objective: To study microstructure, friction and wear behaviors of silicon-lithium spray coating on the surface of zirconia ceramics and to preliminarily evaluate its esthetic so as to provide support and guidance for the clinical application.
Methods: Zirconia ceramic specimens were randomly divided into three groups: coating group (two subgroups), polishing group (two subgroups), and glazing group (four subgroups), with 10 samples in each subgroup. The two subgroups of coating group were the zirconia ceramics with the untreated and preliminary polishing surfaces sprayed with silicon-lithium coating, respectively. The two subgroups of polishing group were preliminary polishing and fine polishing of zirconia ceramics, respectively. The four subgroups of glazing group were preliminarily polished zirconia ceramics glazed with Biomic and Stain/Glaze products, respectively; and untreated zirconia ceramics glazed with Biomic and Stain/Glaze products, respectively. The above 8 subgroups of zirconia ceramic specimens were used as friction pairs with 80 steatite ceramics for 50 000 chewing cycles under 50 N vertical load and artificial saliva lubrication using chewing simulation. Scanning electron microscope was used to observe the microstructure of the surface and section of the coating group, and the thickness of the coating and glazing were measured. The linear roughness of the coating and polishing groups was mea-sured using a laser confocal scanning microscope. Vickers hardness was measured using a microhardness tester and the esthetic of zirconia ceramic full crown sprayed with silicon-lithium coating was preliminarily evaluated. White light interferometer was used to measure the width, the maximum depth and the volume of the wear scars of each group, and the wear depth of steatite ceramics and wear rate of zirconia ceramic specimens were calculated. Kruskal-Wallis nonparametric test and Dunn's multiple comparisons test were used to analyze the wear depth of each group (α=0.05).
Results: The microstructures of the silica-lithium spray coatings on the untreated and preliminarily polished zirconia ceramic surfaces showed the protruding defects, and the line roughness of coating group was larger than that of the polishing group. The median thickness of the silica-lithium spray coating on the preliminarily polished zirconia ceramic was 13.0 μm (interquartile range, IQR: 11.6, 17.9), while that of the silica-lithium spray coating on the untreated zirconia ceramic was 4.4 μm (IQR: 4.1, 4.7). The Vickers hardness and wear rate of the coating group were between the polishing group and the glazing group. The wear depths of the wear scars of steatite ceramics were the glazing group, coating group, and polishing group in descending order, and there was statistically significant difference between glazing and polishing groups (P < 0.05). With the increase of polishing procedure, the wear depth of steatite ceramics decreased in each subgroups. The orders of maximum depth and volume of wear scars of zirconia ceramic were the glazing group, coating group, and polishing group in descending order, and there was statistically significant difference in the maximum depth of wear scars between glazing and polishing groups (P < 0.05).
Conclusion: The silica-lithium spray coating on the zirconia ceramic, can be used as a new method for zirconia ceramic surface treatment, because it can increase the esthetic of zirconia ceramics compared with polishing and reduce the wear of steatite ceramics compared with glazing.
目的: 研究氧化锆陶瓷表面硅锂喷涂层的微观形貌和摩擦磨损性能, 初步评估其美观效果, 为其临床应用提供指导和支持。
方法: 将氧化锆陶瓷试样随机分为三组: 涂层组(有2个亚组)、抛光组(有2个亚组)和上釉组(有4个亚组), 每个亚组10个样本。涂层组的两个亚组是对未处理和初步抛光的氧化锆陶瓷表面分别喷涂硅锂喷涂层; 抛光组的两个亚组分别是氧化锆陶瓷表面初步抛光和精细抛光; 上釉组的4个亚组分别是对初步抛光的氧化锆陶瓷表面分别上Biomic釉和Stain/Glaze釉, 未处理的氧化锆陶瓷表面分别上Biomic釉和Stain/Glaze釉。对磨物选用滑石瓷球, 与上述8个亚组的氧化锆陶瓷试样构成摩擦副。应用扫描电镜观测涂层组表面和断面的微观形貌, 测量涂层和釉层的厚度; 应用激光三维形貌显微镜测量涂层组和抛光组表面的线粗糙度; 应用显微硬度计测量各组的维氏硬度。制作氧化锆陶瓷全冠, 初步评价硅锂喷涂层的美观效果。应用口腔咀嚼模拟试验机, 在50 N垂直载荷及人工唾液润滑下进行50 000次咀嚼循环的摩擦磨损试验。应用白光干涉仪, 测量滑石瓷球磨斑的宽度并计算其磨损深度; 测量氧化锆陶瓷试件磨斑的最大深度和体积, 计算磨损率。应用Kruskal-Wallis非参数检验和Dunn's多重检验分析各组的磨损深度, 检验水准α = 0.05。
结果: 氧化锆陶瓷表面未处理和初步抛光后形成的两种硅锂喷涂层微观形貌均有突起缺陷, 两者的线粗糙度均大于抛光组。氧化锆陶瓷表面初步抛光后形成的硅锂喷涂层厚度中位数为13.0 μm [四分位距(interquartile range, IQR): 11.6, 17.9], 氧化锆陶瓷表面未处理形成的硅锂喷涂层厚度中位数为4.4 μm(IQR: 4.1, 4.7)。涂层组的维氏硬度值和磨损率均介于抛光组和上釉组之间。对磨的滑石瓷球磨斑深度由大到小依次是上釉组、涂层组和抛光组, 上釉组和抛光组的滑石瓷球磨损深度差异有统计学意义(P < 0.05);各组内随着抛光程度的增加, 滑石瓷球的磨损深度减小。各氧化锆陶瓷试件磨斑的最大深度和体积由大到小依次是上釉组、涂层组和抛光组, 上釉组和抛光组的氧化锆陶瓷试件的磨损深度差异有统计学意义(P < 0.05)。
结论: 氧化锆陶瓷表面硅锂喷涂层与抛光处理相比, 增加了氧化锆陶瓷表面美观; 与上釉处理相比, 减少了对磨的滑石瓷球的磨损, 可以作为一种氧化锆陶瓷表面处理的新方法。
Keywords: Friction and wear behaviors; Silicon-lithium spray coating; Surface treatment; Zirconia ceramics.