Statement of problem

Displacement of impression copings and/or implant replicas during impression making and dimensional changes that occur during clinical and laboratory phases of making multiunit implant prostheses may affect the accuracy and fit of the prostheses.

Purpose

The purpose of this qualitative study was to investigate and compare 3 different impression techniques for osseointegrated dental implant transfer procedures.

Material and methods

Three impression transfer approaches were evaluated and compared: closed-tray impression technique (CTT), impression with plastic snap-fit impression copings; open-tray impression technique (OTT), impression with independent square copings; and OTT joining the impression copings with a photo-polymerized resin (PPT). A reference acrylic resin model with 4 implants was fabricated. Polyvinyl siloxane with a stock tray was used to make 45 impressions (n=15 for each impression technique), and 45 die definitive stone casts. A computer-aided design and computer-aided manufacturing (CAD-CAM) titanium framework was fabricated on the reference model. Three blinded operators evaluated the fit of the CAD-CAM titanium framework on each model to find clinically acceptable fit. The Kappa test was used for the agreement between the examiners (α=.05).

Results

Agreement was found among the 3 examiners on 44 of 45 specimens (Kappa value= 0.939; P<.001). In the CTT group, 14 casts were found to be acceptable. In the OTT group, nearly half of the specimens produced unacceptable fitting casts, whereas in the PPT group, 13 casts were found acceptable.

Conclusions

CTT and PPT produced more accurate casts than the OTT technique, which yielded inferior results.

中文翻译：

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用于多单元植入物修复的不同压印技术的准确性：一项定性的体外研究。

问题陈述

在制造印模期间，印模顶盖和/或植入物复制品的移位以及在制造多单元植入物假体的临床和实验室阶段发生的尺寸变化可能会影响假体的准确性和适合性。

目的

这项定性研究的目的是研究和比较3种不同的压印技术，用于骨整合式牙科植入物转移程序。

材料与方法

评估并比较了三种印模转移方法：封闭托盘印模技术（CTT），带有塑料卡扣配合印模的印模；开放式托盘印象技术（OTT），具有独立的方形顶盖的印象；OTT用光聚合树脂（PPT）将压印顶盖连接起来。制作了具有4个植入物的参考丙烯酸树脂模型。带有储料盘的聚乙烯基硅氧烷用于制作45个压痕（每种压痕技术的n = 15）和45个定型石模。在参考模型上制作了计算机辅助设计和计算机辅助制造（CAD-CAM）钛框架。三位盲人操作员评估了每种模型上CAD-CAM钛框架的适合度，以找到临床上可接受的适合度。Kappa检验用于检查员之间的一致性（α= .05）。

结果

3名检查员对45个样本中的44个样本发现一致（卡帕值= 0.939；P <.001）。在CTT组中，发现14个演员是可以接受的。在OTT组中，近一半的标本产生了不合格的管件，而在PPT组中，发现有13个管件是可以接受的。

结论

与OTT技术相比，CTT和PPT产生的铸模更为精确，其结果较差。