Statement of problem

Adaptation between abutment and suprastructure plays a crucial role in the long-term success of implant-supported metal-ceramic crowns. Fabrication methods, the porcelain firing stage, and cementation techniques may affect the marginal adaptation between the crown and abutment. However, the information regarding this issue is sparse.

Purpose

The purpose of this in vitro study was to compare marginal fit after the fabrication of cobalt-chromium alloy copings, porcelain firing, and cementation of metal-ceramic restorations that were fabricated with computer-aided design and computer-aided manufacturing (CAD-CAM) milling and direct metal laser sintering techniques.

Material and methods

Thirty straight tissue-level titanium abutments were screwed onto implant analogs. All specimens were embedded in acrylic resin and divided into 2 groups according to CAD-CAM milling and direct metal laser sintering fabrication of the metal coping. Fifteen cobalt-chromium implant-supported metal copings were fabricated by using the CAD-CAM milling technique and 15 by using the direct metal laser sintering technique. In both groups, marginal gap measurements between the cobalt-chromium copings and abutments were obtained before (T0) and after the placement of the ceramic veneer (T1) and after cementation (T2) by using a stereomicroscope with a magnification of ×40. The data were statistically evaluated by using 2-way ANOVA and the Tukey post hoc test (α=.05). A t test was used to determine whether there were significant differences between the fabrication techniques (α=.05).

Results

A significant difference in the fabrication stages was found in the direct metal laser sintering group. The direct metal laser sintering coping group and porcelain applied direct metal laser sintering group had a statistically lower marginal gap value than the cemented direct metal laser sintering group (P=.021, P=.038). The direct metal laser sintering coping group had a lower marginal gap value than the CAD-CAM milling coping group, although the difference was not statistically significant (P=.216).

Conclusions

Porcelain firing and cementation increased the marginal gap between the crown and abutment. No statistically significant differences were found between the direct metal laser sintering and CAD-CAM milling techniques in terms of marginal fit.

中文翻译：

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瓷烧制和胶结对通过加法或减法制造方法制造的植入物支持的金属陶瓷修复体边缘拟合的影响。

问题陈述

基台和上部结构之间的适应在植入物支持的金属陶瓷冠的长期成功中起着至关重要的作用。制造方法，瓷烧制阶段和胶结技术可能会影响冠和基台之间的边缘适应性。但是，有关此问题的信息很少。

目的

这项体外研究的目的是比较用计算机辅助设计和计算机辅助制造（CAD-CAM）制造的钴铬合金顶盖，瓷烧以及金属陶瓷修复体胶结后的边缘拟合。铣削和直接金属激光烧结技术。

材料与方法

将三十个直的组织水平钛基台拧到植入类似物上。所有样品均嵌入丙烯酸树脂中，根据CAD-CAM铣削和金属帽的直接金属激光烧结制造，分为2组。使用CAD-CAM铣削技术制造了15个钴铬植入物支撑的金属顶盖，使用直接金属激光烧结技术制造了15个。在两组中，均通过使用倍数为40倍的体视显微镜在（T0）放置陶瓷贴面之前（T0）和之后（T1）以及粘结之后（T2）获得了钴-铬涂层和基台之间的边际间隙测量值。通过使用2通ANOVA和Tukey post hoc检验（α= .05）对数据进行统计学评估。一个牛逼 测试用于确定制造工艺之间是否存在显着差异（α= .05）。

结果

在直接金属激光烧结组中发现了制造阶段的显着差异。在统计学上，直接金属激光烧结应对组和陶瓷涂覆的直接金属激光烧结组的边缘间隙值在统计学上低于胶凝直接金属激光烧结组（P = .021，P = .038）。直接金属激光烧结应对组的边际间隙值低于CAD-CAM铣削应对组，尽管差异无统计学意义（P = .216）。

结论

瓷器的烧制和胶结增加了牙冠和基台之间的边缘间隙。在直接金属激光烧结和CAD-CAM铣削技术之间，在边缘配合方面没有发现统计学上的显着差异。