Zhou Yi, Chen Wenjia, Zhu Han, Liu Xiaochen, Yang Haiping, He Fuming
Attending, Department of Prosthodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China.
Graduate student, Department of Prosthodontics, Stomatology Hospital, School of Stomatology, Zhejiang University School of Medicine, Clinical Research Center for Oral Diseases, Key Laboratory of Oral Biomedical Research of Zhejiang Province, Cancer Center of Zhejiang University, Engineering Research Center of Oral Biomaterials and Devices of Zhejiang Province, Hangzhou, PR China.
J Prosthet Dent. 2025 Feb;133(2):592.e1-592.e9. doi: 10.1016/j.prosdent.2024.10.012. Epub 2024 Nov 3.
The machining accuracy and marginal integrity of monolithic zirconia crowns with minimal invasive preparations may impact the long-term survival rate of tooth and periodontal health, but studies on the effect of machining method are lacking.
The purpose of this in vitro study was to digitally evaluate the machining accuracy and margin quality of monolithic zirconia crowns fabricated using gel deposition and conventional soft milling processes by comparing 2 different margin types.
A total of 40 monolithic zirconia crowns were produced using gel deposition (Self-glazed Zirconia Group, SGG, n=20) and soft milling (Milled Zirconia Group, MG, n=20). Each group was further divided into 2 subgroups with different margin designs (chamfer and feather-edge). The trueness and fit of crowns were compared using root mean square (RMS) values. Furthermore, the margin quality was examined before and after final sintering with a scanning electron microscope (SEM). The Scheirer-Ray-Hare and 2-way ANOVA test analysis nonparametric and parametric data, respectively (α=.05).
The trueness analysis revealed that SGG had significantly lower RMS values for both the cameo and intaglio areas compared with MG (P<.001). In addition, crowns with a feather-edge margin exhibited significantly lower marginal RMS values than those with a chamfer margin (P<.01) according to the fit assessment. Followed by milling processes, SGG exhibited a constantly homogeneous microstructure compared with MG. Marginal defects were detected in both groups except for the SGG with the chamfer margin.
SGG exhibited better accuracy associated with ductile-regime machining than MG, and SGG with chamfer margins displayed flaw-free margin areas. Moreover, the feather-edge margin showed improved marginal fit compared with the chamfer margin.
微创预备的整体式氧化锆全冠的加工精度和边缘完整性可能会影响牙齿的长期存活率和牙周健康，但关于加工方法影响的研究尚缺乏。
本体外研究的目的是通过比较两种不同的边缘类型，以数字方式评估采用凝胶沉积和传统软铣削工艺制作的整体式氧化锆全冠的加工精度和边缘质量。
使用凝胶沉积（自釉质氧化锆组，SGG，n = 20）和软铣削（铣削氧化锆组，MG，n = 20）制作了总共40个整体式氧化锆全冠。每组进一步分为具有不同边缘设计（倒角和羽状边缘）的两个亚组。使用均方根（RMS）值比较全冠的准确性和贴合度。此外，在最终烧结前后用扫描电子显微镜（SEM）检查边缘质量。Scheirer-Ray-Hare检验和双向方差分析分别分析非参数和参数数据（α = .05）。
准确性分析表明，与MG相比，SGG在浮雕和凹雕区域的RMS值均显著更低（P < .001）。此外，根据贴合度评估，具有羽状边缘的全冠的边缘RMS值显著低于具有倒角边缘的全冠（P < .01）。在铣削工艺之后，与MG相比，SGG呈现出持续均匀的微观结构。除了具有倒角边缘的SGG组外，两组均检测到边缘缺陷。
与MG相比，SGG在延性加工状态下表现出更好的精度，并且具有倒角边缘的SGG显示出无缺陷的边缘区域。此外，与倒角边缘相比，羽状边缘显示出更好的边缘贴合度。
