Khamverdi Zahra, Najafrad Elmira, Farhadian Maryam
Dental Research Center, Department of Restorative Dentistry, Faculty of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran.
Department of Restorative Dentistry, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
Front Dent. 2021 Jan 20;18:2. doi: 10.18502/fid.v18i2.5432. eCollection 2021.
Marginal and internal fit of restorations are two important clinical factors for assessing the quality and durability of computer-aided design/computer-aided manufacturing (CAD/CAM)-fabricated monolithic zirconia restorations. The purpose of this study was to evaluate the marginal and internal fit of CAD/CAM zirconia crowns with two different scanners (i3D scanner and 3Shape D700). Twelve extracted sound human posterior teeth were prepared for full zirconia crowns. Two different extraoral scanners namely i3D scanner and 3Shape D700 were used to digitize type IV gypsum casts poured from impressions. The crowns were milled from presintered monolithic zirconia blocks by a 5-axis milling machine. The replica technique and MIP4 microscopic image analysis software were utilized to measure the marginal and internal fit by a stereomicroscope at ×40 magnification. The collected data were analyzed by paired t-test. The mean marginal gap was 203.62 μm with 3Shape D700 scanner and 241.07 μm with i3D scanner. The mean internal gap was 192.30 μm with 3Shape D700 scanner and 196.06 μm with i3D scanner. The results of paired t-test indicated that there was a statistically significant difference between the two scanners in marginal fit (P=0.04); while, there was no statistically significant difference in internal fit (P=0.761). Within the limitations of this study, the results showed that type of extraoral scanner affected the marginal fit of CAD/CAM fabricated crowns; however, it did not have a significant effect on their internal fit.
修复体的边缘适合性和内部适合性是评估计算机辅助设计/计算机辅助制造（CAD/CAM）制作的整体式氧化锆修复体质量和耐久性的两个重要临床因素。本研究的目的是评估使用两种不同扫描仪（i3D扫描仪和3Shape D700）制作的CAD/CAM氧化锆全冠的边缘适合性和内部适合性。选取12颗拔除的完好人类后牙，预备制作全氧化锆全冠。使用两种不同的口外扫描仪，即i3D扫描仪和3Shape D700，对从印模灌注的IV型石膏模型进行数字化。通过五轴铣床从预烧结的整体式氧化锆块铣削制作全冠。采用复制技术和MIP4显微图像分析软件，在×40放大倍数下通过体视显微镜测量边缘适合性和内部适合性。收集的数据采用配对t检验进行分析。使用3Shape D700扫描仪时平均边缘间隙为203.62μm，使用i3D扫描仪时为241.07μm。使用3Shape D700扫描仪时平均内部间隙为192.30μm，使用i3D扫描仪时为196.06μm。配对t检验结果表明，两种扫描仪在边缘适合性方面存在统计学显著差异（P=0.04）；而在内部适合性方面无统计学显著差异（P=0.761）。在本研究的局限性范围内，结果表明口外扫描仪的类型会影响CAD/CAM制作全冠的边缘适合性；然而，对其内部适合性没有显著影响。
