Effect of Anti-Rotational Abutment Features and Novel Computerized Fabrication Techniques on the Marginal Fit of Implant-Supported Metal Copings.

Abstract

Purpose: An in vitro study to compare the marginal fit of cobalt-chromium (Co-Cr) metal copings fabricated with selective laser melting (SLM), computer-aided design and computer-aided manufacturing (CAD/CAM) milling, and lost-wax (LW) techniques, on abutments with two different anti-rotational features.

Materials and methods: A total of 60 stainless steel abutments with the same length and convergence angles were fabricated using a numerical control machining. Half of the abutments had one flat plane, while the other half had three grooves as an anti-rotation feature. Thirty abutments of each kind were then divided into three subgroups, and metal copings were fabricated with SLM, CAD/CAM milling, or the LW technique (n = 10). The metal copings were cemented with polycarboxylate cement. Marginal gap measurements were performed using a stereomicroscope at a magnification of × 45 and data were analyzed with two-way analysis of variance (ANOVA) tests.

Results: The LW (p = 0.002) and CAD/CAM (p<0.001) techniques exhibited increased marginal gaps on the abutments with a three groove anti-rotational feature; however, no significant difference was detected with the SLM technique (p = 0.259). The copings fabricated with the SLM technique demonstrated significantly lower gap values in both abutment types (p<0.001).

Conclusion: While all marginal gap values were within the clinically acceptable range (<120μm), abutments with more anti-rotational grooves exhibited wider marginal gaps with the LW and CAD/CAM techniques. This article is protected by copyright. All rights reserved.