Department of Prosthodontics, University of Catalunya, Barcelona, Spain.
J Prosthodont. 2012 Jun;21(4):291-5. doi: 10.1111/j.1532-849X.2011.00831.x. Epub 2012 Feb 28.
The purpose of this study was to evaluate the marginal adaptation of zirconium dioxide crowns in preparations with two different finish line configurations before and after porcelain firing cycles, after a glaze cycle, and after cementation.
Twenty human molar teeth were prepared to receive full crowns; ten were prepared with a 90° round shoulder and another ten with a 45° chamfer finish line. Zirconium dioxide copings were fabricated using CAD/CAM technology (Lava™ system). They were then veneered with a low-fusing glass-ceramic (IPS e.max® Ceram). Finally, they were glazed and cemented with a resin-composite cement (RelyX™ Unicem, Aplicap™). Measurements for marginal adaptation using stereomicroscopy (40×) were performed at four stages: copings (S1), after porcelain firing cycles (S2), after glazing (S3), and after cementation (S4). One-way ANOVA was used to assess the influence of the finish line design on the marginal adaptation in each stage. Two-way ANOVA with repeated measurements was performed to assess the influence on the marginal adaptation of the porcelain firing cycles, glaze firing cycle, and cementation.
The measured marginal gap mean values for the shoulder group (μm) were: 50.13 (S1), 54.32 (S2), 55.12 (S3), and 59.83 (S4). The values for the chamfer group were: 63.56 (S1), 71.85 (S2), 74.12 (S3), and 76.97 (S4). When comparing marginal gaps between specimens with two different finish lines, differences were noticed at the four studied stages (p = 0.0165, p = 0.0027, p = 0.0009, and p = 0.0009, respectively). No differences were manifested in the marginal gap measurements of the shoulder group at the different stages of fabrication (p = 0.4335); however, in the chamfer group, differences were noticed between S1 and S3 (p = 0.0042).
Marginal adaptation was influenced by the finish line design. The firing cycles significantly affected the chamfer group; nevertheless, the marginal gap was within the range of clinical acceptability.
本研究的目的是评估两种不同边缘线设计的二氧化锆冠在预备体经过烤瓷循环、上釉循环和粘结后的边缘适合性。
将 20 个人类磨牙制备成全冠修复体，10 个预备体采用 90°肩台，另外 10 个预备体采用 45°倒角边缘线。使用 CAD/CAM 技术（Lava™系统）制作氧化锆基底冠。基底冠涂以低熔玻璃陶瓷（IPS e.max® Ceram），最后上釉并用树脂复合粘结剂（RelyX™ Unicem，Aplicap™）粘结。使用立体显微镜（40×）在四个阶段（基底冠 S1、烤瓷循环后 S2、上釉后 S3、粘结后 S4）测量边缘适合性。采用单因素方差分析评估边缘线设计对各阶段边缘适合性的影响。采用双向方差分析和重复测量评估烤瓷循环、上釉循环和粘结对边缘适合性的影响。
肩台组的边缘间隙均值（μm）为：50.13（S1）、54.32（S2）、55.12（S3）和 59.83（S4）。倒角组的边缘间隙均值为：63.56（S1）、71.85（S2）、74.12（S3）和 76.97（S4）。比较两种不同边缘线设计的试件边缘间隙，四个研究阶段均有差异（p = 0.0165、p = 0.0027、p = 0.0009 和 p = 0.0009）。肩台组在各阶段的制备过程中，边缘间隙测量值无差异（p = 0.4335）；然而，在倒角组中，S1 和 S3 之间有差异（p = 0.0042）。
边缘适合性受边缘线设计影响。烤瓷循环对倒角组有显著影响，但边缘间隙仍在临床可接受范围内。
