用数字方法和传统方法制作的牙冠边缘适合性比较。
A comparison of the marginal fit of crowns fabricated with digital and conventional methods.
作者信息
Ng Jonathan, Ruse Dorin, Wyatt Chris
机构信息
Student, Graduate Prosthodontics Program, Faculty of Dentistry, The University of British Columbia, Vancouver, British Columbia, Canada.
Professor, Division of Biomaterials, Faculty of Dentistry, The University of British Columbia, Vancouver, British Columbia, Canada.
出版信息
J Prosthet Dent. 2014 Sep;112(3):555-60. doi: 10.1016/j.prosdent.2013.12.002. Epub 2014 Mar 11.
STATEMENT OF PROBLEM
Little evidence is available with regard to the marginal fit of crowns fabricated with digital impressions and computer-aided design/computer-aided manufacturing technology in comparison with crowns fabricated from conventional techniques.
PURPOSE
The purpose of this study was to determine and compare the marginal fit of crowns fabricated with digital and conventional methods.
MATERIAL AND METHODS
The maxillary right second premolar was prepared for a ceramic crown in a typodont. The typodont was then digitized with a laboratory scanner, and the digital file was used to mill a replica of the maxillary arch from a monolithic block of yttria-stabilized zirconia to serve as the master model. Digital impressions of the prepared maxillary right second premolar were recorded with a scanning unit. Scan files were exported as .STL files and sent by e-mail to a dental laboratory. The files were input into a digital design workflow for digital articulation, digital waxing, and design of the definitive crown. Fifteen crowns were produced by milling computer-aided designed lithium disilicate glass ceramic blocks with a 5-axis milling. Fifteen lithium disilicate glass ceramic crowns were produced with a conventional impression and a laboratory fabrication method. The original zirconia die was removed from the zirconia master model to evaluate the crown margins. Circumferential marginal gap measurements were made at 8 measurement locations: mescal, distal, buccal, palatal and associated line angles (mesiobuccal, mesiolingual, distobuccal, and distolingual). Measurements were made to determine the vertical component of the marginal gap according to the definition of marginal fit.
RESULTS
A total of 240 images (2 groups, 15 crowns per group, 8 sites per crown) were recorded and measured. The overall mean ±SD vertical gap measurement for the digitally made crowns was 48 ±25 μm, which was significantly smaller than that for the conventionally made crowns (74 ±47 μm).
CONCLUSION
The fully digital fabrication method provided better margin fit than the conventional method.
问题陈述
与采用传统技术制作的牙冠相比，关于使用数字印模和计算机辅助设计/计算机辅助制造技术制作的牙冠的边缘适合性，现有证据较少。
目的
本研究的目的是确定并比较用数字方法和传统方法制作的牙冠的边缘适合性。
材料与方法
在一个模型牙上制备上颌右侧第二前磨牙的陶瓷牙冠。然后用实验室扫描仪对模型牙进行数字化处理，并用数字文件从整块氧化钇稳定氧化锆中铣削出上颌牙弓的复制品作为主模型。用扫描单元记录制备好的上颌右侧第二前磨牙的数字印模。扫描文件导出为.STL文件并通过电子邮件发送到牙科实验室。这些文件被输入到数字设计工作流程中进行数字咬合、数字蜡型制作以及最终牙冠的设计。通过五轴铣削计算机辅助设计的二硅酸锂玻璃陶瓷块制作15个牙冠。用传统印模和实验室制作方法制作15个二硅酸锂玻璃陶瓷牙冠。从氧化锆主模型上取下原始氧化锆代型以评估牙冠边缘。在8个测量位置进行圆周边缘间隙测量：近中、远中、颊侧、腭侧以及相关线角（近中颊侧、近中舌侧、远中颊侧和远中舌侧）。根据边缘适合性的定义进行测量以确定边缘间隙的垂直分量。
结果
总共记录并测量了240张图像（2组，每组15个牙冠，每个牙冠8个部位）。数字制作的牙冠的总体平均±标准差垂直间隙测量值为48±25μm，显著小于传统制作的牙冠（74±47μm）。
结论
全数字制作方法比传统方法提供了更好的边缘适合性。
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