Statement of problem

Selective laser melting additive manufacturing (AM) technologies can be used to fabricate complete-arch cobalt-chromium (Co-Cr) implant-supported prostheses. However, the discrepancy at the implant-prosthesis interface with these fabrication techniques and after ceramic veneering remains unclear.

Purpose

The purpose of the present in vitro investigation was to measure the discrepancy at the implant abutment-prosthesis interface before and after the ceramic veneering of frameworks fabricated by using subtractive and selective laser melting AM technologies.

Material and methods

A completely edentulous cast with 6 implant abutment replicas (Multi-unit Abutment RP Replicas; Nobel Biocare Services AG) was prepared. A total of 20 Co-Cr frameworks were fabricated using subtractive or computer numerical control milling (CNC group) and additive (AM group) technologies (n=10). A coordinate measurement machine was used to measure the linear and angular discrepancy at the implant abutment-prosthesis interface. Subsequently, a ceramic veneer was applied to each framework following the same standardized protocol. A bonding layer (Chromium-Cobalt Bonding; Bredent), 2 opaquer layers (Powder opaque and liquid UF; Creation CC), a layer of dentin ceramic (Dentine A3; Creation CC), a layer of enamel ceramic (Enamel S-59; Creation CC), and a glaze layer (Glaze paste and Liquid GL; Creation CC) were applied following the manufacturer’s firing protocol. Coordinate measurement machine assessment was repeated to measure the linear and angular discrepancies after ceramic veneering procedures. Data were analyzed by using the Wilcoxon signedrank and Mann-Whitney U tests (α=.05).

Results

No statistically significant differences (P>.05) were demonstrated in assessing the discrepancies at the implant abutment-prosthesis interface between the groups except for the XZ angle of the CNC group (P<.05). Ceramic techniques produced significantly higher linear and angular discrepancies in both groups (P<.001) with a mean ±standard deviation increase in the 3-dimensional gap of 36.9 ±15.6 μm in the CNC group and 38.9 ±16.6 μm in the AM group. The AM group presented significantly higher discrepancy in the x-axis than the CNC group (P<.001).

Conclusions

Manufacturing procedures did not significantly influence the discrepancy at the implant abutment-prosthesis interface, which was significantly increased after ceramic veneering, except for the XZ angle of the CNC group. The differences between the discrepancies at the implant abutment-prosthesis interface before and after ceramic application revealed no significant discrepancies among the groups, except in the AM group that presented a significantly higher discrepancy on the x-axis compared with the CNC group.

中文翻译：

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陶瓷饰面前后通过加减法制造的完整弓形钴铬植入物框架在植入物基台-假体界面上的差异

问题陈述

选择性激光熔融增材制造（AM）技术可用于制造完整弓形钴铬（Co-Cr）植入物支持的假体。然而，尚不清楚这些制造技术在植入物-假体界面上的差异以及在陶瓷贴面之后的差异。

目的

本次体外研究的目的是在通过消减和选择性激光熔化AM技术制造的框架的陶瓷贴面之前和之后，测量植入物基台-假体界面的差异。

材料与方法

准备了一个带有6个种植体基台复制品（多单元基台RP复制品； Nobel Biocare Services AG）的完全无牙的铸件。使用减法或计算机数控铣削（CNC组）和添加剂（AM组）技术（n = 10）制造了总共20个Co-Cr框架。使用坐标测量机测量植入物基台-假体界面的线性和角度差异。随后，按照相同的标准化协议将陶瓷贴面应用于每个框架。粘结层（铬-钴粘结；不透明），2个不透明层（粉末不透明和液体UF； Creation CC），一层牙本质陶瓷（Dentine A3； Creation CC），一层搪瓷陶瓷（Enamel S-59； Creation CC）和釉层（釉浆和Liquid GL；按照制造商的烧制规程应用Creation（CC）。重复进行坐标测量机评估，以测量陶瓷贴面步骤后的线性和角度差异。使用Wilcoxon符号秩和Mann-Whitney U检验（α= .05）分析数据。

结果

除评估CNC组的XZ角外，在评估各组之间的种植体基台与假体界面的差异方面，没有发现统计学上的显着差异（P > .05）（P <.05）。陶瓷技术在两组中产生了更高的线性和角度差异（P <.001），其中3维间隙的平均值±标准偏差在CNC组中为36.9±15.6μm，在AM组中为38.9±16.6μm。AM组在x轴上的差异明显高于CNC组（P <.001）。

结论

制造程序并没有显着影响植入物基台-假体界面的差异，在陶瓷贴面后，差异显着增加，但CNC组的XZ角除外。陶瓷应用前后，种植体基台-假体界面的差异之间的差异没有显示出显着差异，除了AM组，与CNC组相比，x轴上的差异明显更高。