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Title: [Effects of different surface modifications on micro-structure and adhesion of zirconia ceramic: an in vitro study].
Author: Siwen L, Shishi L, Yanhong W, Hongmei M.
Journal: Hua Xi Kou Qiang Yi Xue Za Zhi; 2017 Feb 01; 35(1):43-50. PubMed ID: 28326726.
Abstract:
OBJECTIVE: This study evaluated the effect of different mechanical-chemical surface treatments on the characteristics, microstructure, and composition of zirconia ceramics and on the zirconia-dentin adhesion. METHODS: The sintered commercial zirconia blocks (IPS e.max ZirCAD) were sectioned into 126 beams (6 mm×6 mm×5 mm) and randomly assigned to seven experimental groups (n=18). The zirconia block specimens were further treated as follows: (A) untreated, as control; (B) sandblasted with 50 μm Al2O3; (C) sandblasted with 50 μm Al2O3+30 μm silica powder; (D) sandblasted with 50 μm Al2O3+30% silica-sol coating; (E) sandblasted with 110 μm Al2O3; (F) sandblasted with 110 μm Al2O3+30 μm silica powder; and (G) sandblasted with 110 μm Al2O3+30% silica-sol coating. The surface roughness (Ra) of zirconia ceramics using X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) after seven surface treatments was analyzed. Seventy specimens of dentin surfaces were prepared. A dual-cure resin cement was applied into zirconia surfaces with its corresponding adhesive components to dentin. Shear bond strength (SBS) of each sample was measured using a universal testing machine. The data were analyzed by ANOVA using SPSS 17.0 software. RESULTS: Ra of zirconia were significantly different compared with the control group (P<0.05). The crystalline transformation from tetragonal phase to monoclinic phase was observed after surface modification. Monoclinic volume content of the heat-treated group was highest than that in other groups. The content of element Si in the heat-treated group was higher than that in other treatment groups accompanied by a decrease in elements Zr, Y, and Hf after being treated by two silica-coating methods. Air abrasion significantly increased the micro-cracks in the ceramic surface and caused the grain boundaries to disappear. A serious shrinkage of the thin silica film can be observed after sintering procedure. This process induced cracks and the film to strip away slightly from the surfaces of Y-TZP substrate. The SBS values from large to small were F and G groups, C and D groups, B and E groups (P<0.05), and control group (P<0.05). CONCLUSIONS: Alumina sandblasting, silica powder abrasion, and silica-sol coating affect the surface morphology, structure, and composition of the tooth. This effect can also achieve the improved micro-mechanical interlocking or chemical bonding and finally increase the bond strength between zirconia and tooth. Alumina sandblasting followed by silica coating is an effective technique to increase the bonding strength between the zirconia ceramic and dentin. . 目的研究不同机械-化学性表面处理对氧化锆陶瓷表面微观形貌、结构及组成的影响，比较不同表面改性后的氧化锆陶瓷与人牙本质的粘接强度。方法选择氧化锆陶瓷（IPS e.max ZirCAD），切割并烧结形成长6 mm、宽6 mm、高5 mm瓷块126块，随机分为7组，每组18块，分别进行如下处理。A组：不处理，对照组；B组：50 μm氧化铝喷砂；C组：50 μm氧化铝喷砂+30 μm二氧化硅蚀刻；D组：50 μm氧化铝喷砂+30%硅溶胶涂层；E组：110 μm氧化铝喷砂；F组：110 μm氧化铝喷砂+30 μm二氧化硅蚀刻；G组：110 μm氧化铝喷砂+30%硅溶胶涂层。每组随机抽取2个试件，分别用表面粗糙度轮廓仪测量表面粗糙度（Ra），X射线衍射（XRD）观察表面晶相结构，能谱分析仪（EDX）分析表面化学元素组成，扫描电镜（SEM）观察表面微观形貌。收集70颗人离体第三磨牙制备成牙本质平面。使用双固化树脂水门汀将氧化锆试件与牙本质平面粘接，万能试验机进行剪切粘接强度（SBS）测试。采用SPSS 17.0软件对结果进行单因素方差分析及多重检验。结果与对照组相比，表面处理后的氧化锆陶瓷Ra具有显著性差异（P<0.05）。所有表面处理后都发生了四方相（t）到单斜相（m）的晶相转换，且热处理后的m相体积分数最多。表面改性后化学元素组成发生变化，EDX结果显示硅涂层后，硅元素含量显著升高，Zr、Y、Hf减少。SEM图像显示，氧化铝喷砂后的氧化锆陶瓷表面出现一些微小断裂、晶界消失；硅溶胶薄膜烧结后体积明显收缩，可见裂纹与剥离。不同表面处理组的粘接强度有统计学差异（P<0.05），F和G组SBS值最大，其次为C和D组，显著大于B和E组（P<0.05），对照组的SBS值最小（P<0.05）。结论氧化铝喷砂、硅粉蚀刻、硅溶胶涂层法可显著改变氧化锆陶瓷的表面形貌、结构和组成，有利于氧化锆陶瓷与牙体组织粘接时形成微机械嵌合与化学结合作用。氧化铝喷砂后硅涂层处理是一种比较理想的表面改性方法，可显著提高氧化锆陶瓷与牙体组织的粘接强度。.

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