目的:通过对临床损伤失效的全瓷修复体的损伤形貌观察,分析全瓷修复体饰瓷疲劳损伤的机制和过程,以及缺陷与饰瓷损伤的关系。方法:收集断裂或破碎的全瓷修复体,体式显微镜和扫描电子显微镜(scanning electron microscope,SEM)观察其断...
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目的:通过对临床损伤失效的全瓷修复体的损伤形貌观察,分析全瓷修复体饰瓷疲劳损伤的机制和过程,以及缺陷与饰瓷损伤的关系。方法:收集断裂或破碎的全瓷修复体,体式显微镜和扫描电子显微镜(scanning electron microscope,SEM)观察其断裂面和咬合面微观形貌以及饰瓷的缺陷,X线衍射能谱分析(energy-dispersive X-ray spectroscopy,EDS)饰瓷内不均质部分的化学成分。运用陶瓷损伤形貌分析的方法,分析全瓷修复体的断裂方式和损伤特征。结果:全瓷修复体的最终损伤失效包括完全断裂、饰瓷崩瓷和饰瓷脱瓷3种方式。氧化铝全瓷冠发生了完全断裂,氧化锆全瓷冠发生饰瓷崩瓷或饰瓷脱瓷。饰瓷疲劳损伤包括表面磨损、锥状裂纹和饰瓷脱瓷3种模式。饰瓷表面发现气孔和污染颗粒缺陷。结论:全瓷修复体应设计多点咬合接触,分散咬合应力。饰瓷脱瓷发生于饰瓷层过薄的情况,适当的饰瓷厚度保证饰瓷的抗疲劳损伤能力。临床需严格控制饰瓷烧结过程的环境污染。
目的:采用激光三维扫描技术评估玻璃体和通用型复合树脂用于后牙充填的耐磨性。方法:根据纳入标准选取48名患者共108颗患牙(每组各54颗),随机分配用玻璃体(BeautifilⅡ,简称BF)或通用型复合树脂(Filtek Z350,简称Z350)进行充填。分别于术后1周、6个月、18个月和4年,采用改良美国公共卫生署(United States Public Health Service,USPHS)标准对充填体进行临床评价并拍照和制取模型。使用激光三维扫描仪扫描模型后,对图像进行配准和计算磨耗深度,使用SPSS 20.0进行统计分析。结果:术后4年回访43名患者,回访率为89.6%。BF组和Z350组各有4例和3例出现脱落、继发龋、充填体折断和牙髓坏死。两组充填体的4年存留率均为95.8%,符合美国牙医协会(American Dental Association,ADA)标准(3年存留率>90%)。0~6个月两组充填体的磨耗速率最快,随后磨耗速率的下降趋于平缓,BF组4年总磨耗深度为(58±22)μm,Z350组为(54±16)μm(P>0.05),耐磨性均符合ADA标准(3年磨耗深度<100μm)。两组充填体均表现为围绕咬合接触区形成凹坑状磨耗(Ⅰ型)和充填体发生均匀磨耗(Ⅱ型)。术后4年,Ⅰ型磨耗充填体中,BF组的磨耗深度大于Z350组(P<0.05),Ⅱ型磨耗充填体中,两组间差异无统计学意义(P>0.05)。结论:玻璃体的4年存留率和耐磨性均符合ADA标准,用于后牙牙合面重咬合接触区时,玻璃体的耐磨性略逊于复合树脂,用于非重咬合接触区时,二者间无明显差异。
Statement of problem. When porcelain surfaces oppose gold and composite resin restorations as well as enamel, wear resistance and abrasiveness of the porcelain are clinical concerns to maintain the occlusal relationsh...
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Statement of problem. When porcelain surfaces oppose gold and composite resin restorations as well as enamel, wear resistance and abrasiveness of the porcelain are clinical concerns to maintain the occlusal relationship. However, there is limited information on comparison of mutual wear rates when these materials oppose in 2-body and 3-body conditions. Purpose. The purpose of this study was to evaluate mutual wear rates of dental porcelain and opposing materials, including a gold alloy, a composite resin, and human enamel, using an in vitro wear test. Material and methods. Mutual wear between high-fusing dental porcelain (Ceramco II) disks (9 X 5-mm thick) with a rough or smooth surface and opposing styli made of gold alloy, composite resin, or human enamel was evaluated in 2-body and 3-body conditions using a wear simulator (n=8). Wear depths (mu m) of porcelain disks were determined using a profilometer. Wear depths (mu m) of the opposing materials were obtained by converting the worn surface areas into wear depths using image-analysis software. All data were statistically analyzed by 3-way analysis of variance and Bonferroni-Dunn test (alpha=.05). The worn surfaces were observed by scanning electron microscope (SEM). Results. The wear values for porcelain opposing composite resin or enamel in the 2-body condition were significantly greater than those in the 3-body condition, regardless of the surface condition of the porcelain (P<.001). For stylus specimens, all values in the 2-body condition were significantly greater than those in the 3-body condition, regardless of the surface condition of the opposing porcelain (P<.001). These results are supported by SEM observations of worn surfaces. Conclusion. The results of this stud), suggest that mutual wear rates, when porcelain opposes gold, composite resin, and enamel, are influenced by 2-body and 3-body wear conditions.
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