Faculty of Dentistry, The University of British Columbia, Vancouver, BC, Canada.
Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia.
J Prosthodont. 2020 Oct;29(8):699-706. doi: 10.1111/jopr.13170. Epub 2020 Apr 14.
To evaluate the linear and volumetric dimensional changes that occur throughout the fabrication process of monolithic 4.5-6% yttria-stabilized zirconia copings under the influence of different preparation designs and two sintering protocols.
A titanium master die was fabricated using Atlantis core file implant-abutment. Six copings were designed virtually according to different finish line offsets and coping thicknesses, with four equidistant occlusal posts for linear measurements. Zirconia copings were milled using IPS e.max ZirCAD LT zirconia blanks. The experimental groups according to the coping designs were the following: G1: 0.5 mm finish line offset, 0.5 mm thickness; G2: 0.5 mm finish line offset, 1.0 mm thickness; G3: 0.5 mm finish line offset, 1.5 mm thickness; G4: 1.2 mm finish line offset, 0.5 mm thickness; G5: 1.2 mm finish line offset, 1.0 mm thickness; G6: 1.2 mm finish line offset, 1.5 mm thickness. Six samples per group were sintered by standard sintering (SS) and the other six by fast sintering (FS). Linear and volumetric measurements were taken at the three fabrication stages (virtual design, milling stage, and sintering) by using an intraoral scanner and imported as the .stl file to Meshmixer software for analysis. Statistical analysis was performed by a linear mixed effect model via statistical software R (R Core team, 2018).
There was a significant interaction between the coping design group, stage of fabrication and sintering protocol on the linear (F = 4.451, p < 0.001) and volumetric (F = 2.716; p < 0.001) dimensional changes. Standard sintering G1 showed the smallest linear and dimensional changes among the groups compared to the reference design. Sintered copings had shrunk on average 1.32% within SS and 1.54% within FS linearly and 3.82% within SS and 3.90% within FS volumetrically compared to the initial design parameters.
The linear and volumetric dimensional changes did not differ significantly between standard and fast sintering protocols, and the preparation designs had more influence on the dimensional changes compared to sintering protocols.
评估在不同预备设计和两种烧结方案的影响下，整体式 4.5-6%氧化钇稳定氧化锆修复体在制造过程中发生的线性和体积尺寸变化。
使用 Atlantis 核文件种植体-基台制作钛母模。根据不同的边缘线偏移量和修复体厚度，虚拟设计了 6 个修复体，在 4 个等距的牙合面柱上进行线性测量。使用 IPS e.max ZirCAD LT 氧化锆坯料铣削氧化锆修复体。根据修复体设计的实验组如下：G1：0.5mm 边缘线偏移量，0.5mm 厚度；G2：0.5mm 边缘线偏移量，1.0mm 厚度；G3：0.5mm 边缘线偏移量，1.5mm 厚度；G4：1.2mm 边缘线偏移量，0.5mm 厚度；G5：1.2mm 边缘线偏移量，1.0mm 厚度；G6：1.2mm 边缘线偏移量，1.5mm 厚度。每组 6 个样本分别采用标准烧结（SS）和快速烧结（FS）进行烧结。在三个制造阶段（虚拟设计、铣削阶段和烧结阶段）使用口腔内扫描仪进行线性和体积测量，并将结果作为.stl 文件导入 Meshmixer 软件进行分析。统计分析采用统计软件 R（R Core team，2018）通过线性混合效应模型进行。
在边缘线设计组、制造阶段和烧结方案之间存在显著的交互作用，对线性（F = 4.451，p < 0.001）和体积（F = 2.716；p < 0.001）尺寸变化有显著影响。与参考设计相比，标准烧结 G1 在各组中表现出最小的线性和尺寸变化。与初始设计参数相比，SS 内烧结修复体线性收缩 1.32%，FS 内烧结修复体线性收缩 1.54%；SS 内烧结修复体体积收缩 3.82%，FS 内烧结修复体体积收缩 3.90%。
标准烧结和快速烧结方案之间的线性和体积尺寸变化没有显著差异，预备设计对尺寸变化的影响大于烧结方案。
