Li Rong, Li Weiwei, Wang Yong, Sun Yuchun
Doctoral student, Center of Digital Dentistry, Department of Prosthodontics, Peking University School and Hospital of Stomatology, National Engineering Laboratory for Digital and Material Technology of Stomatology, Research Center of Engineering and Technology for Digital Dentistry of Ministry of Health, Beijing Key Laboratory of Digital Stomatology, National Clinical Research Center for Oral Disease, Beijing, PR China.
Postdoctor, Center of Digital Dentistry, Department of Prosthodontics, Peking University School and Hospital of Stomatology, National Engineering Laboratory for Digital and Material Technology of Stomatology, Research Center of Engineering and Technology for Digital Dentistry of Ministry of Health, Beijing Key Laboratory of Digital Stomatology & National Clinical Research Center for Oral Disease, Beijing, PR China.
J Prosthet Dent. 2023 Jan;129(1):174-180. doi: 10.1016/j.prosdent.2021.04.011. Epub 2021 May 26.
Restorations with knife-edge margins are more prone to margin chipping during the manufacturing process. Three-dimensional gel deposition shows potential for fabricating zirconia restorations with good margin quality, but studies on its performance in fabricating knife-edged crowns are lacking.
The purpose of this in vitro study was to compare the 3-dimensional trueness, surface morphology, and margin quality of self-glazed zirconia and soft-milled zirconia crowns with knife-edge margins.
An abutment with a knife-edge finish line design was prepared and scanned with a laboratory scanner. Anatomic contour crowns were designed and fabricated by 3-dimensional gel deposition and soft milling (n=5). The crowns were digitalized, and the scan data were superimposed on the computer-aided design (CAD) data for 3-dimensional deviation analysis. Surface morphology and margin quality were characterized with microscopic examination.
The self-glazed zirconia crowns showed a smooth and glossy appearance. The soft-milled crowns showed traces left by the removal of support bars and numerous micropits of various sizes. In internal areas, no significant difference was found in root mean square values between the 2 groups (P＞.05). For the external surface, self-glazed zirconia showed statistically lower root mean square values than the soft-milled crowns (P＜.05). When observed at ×5 magnification, all the self-glazed zirconia crowns showed smooth edges with no defects, whereas small or large margin defects were found in the soft-milled crowns. When characterized at ×200 magnification, minor margin flaws were observed in the self-glazed zirconia crowns. More and larger margin defects were found in the soft-milled crowns.
Three-dimensional gel deposition forms a smoother and more homogeneous surface than soft milling. Knife-edged self-glazed zirconia crowns have good dimensional accuracy and margin quality.
刃状边缘修复体在制造过程中更容易出现边缘崩裂。三维凝胶沉积显示出制造边缘质量良好的氧化锆修复体的潜力，但缺乏关于其在制造刃状冠方面性能的研究。
本体外研究的目的是比较具有刃状边缘的自上釉氧化锆和软铣削氧化锆冠的三维精度、表面形态和边缘质量。
制备具有刃状终饰面设计的基台并用实验室扫描仪进行扫描。通过三维凝胶沉积和软铣削设计并制作解剖轮廓冠（n = 5）。将冠数字化，并将扫描数据叠加在计算机辅助设计（CAD）数据上进行三维偏差分析。通过显微镜检查表征表面形态和边缘质量。
自上釉氧化锆冠呈现出光滑有光泽的外观。软铣削冠显示出去除支撑杆后留下的痕迹以及许多大小不一的微坑。在内部区域，两组之间的均方根值无显著差异（P＞.05）。对于外表面，自上釉氧化锆的均方根值在统计学上低于软铣削冠（P＜.05）。在5倍放大倍数下观察时，所有自上釉氧化锆冠的边缘均光滑无缺陷，而软铣削冠中发现有大小不一的边缘缺陷。在200倍放大倍数下表征时，自上釉氧化锆冠中观察到轻微的边缘瑕疵。软铣削冠中发现更多且更大的边缘缺陷。
三维凝胶沉积比软铣削形成更光滑、更均匀的表面。刃状自上釉氧化锆冠具有良好的尺寸精度和边缘质量。
