Evaluation of the Internal and Marginal Discrepancies of Co-Cr Metal Copings Prepared via CAD/CAM and Conventional Casting

European Journal of Prosthodontics and Restorative Dentistry (2019) 27, 26–31

Computer-Aided Design Alloys Computer-Aided Manufacture Marginal Discrepancy Internal Discrepancy

The aim of this study was to assess the internal and marginal discrepancies of chromium-cobalt (Co/Cr) copings fabricated using different techniques. A typodont molar tooth was prepared and replicated in die stone and scanned. Forty Co-Cr alloy copings were produced using four different production techniques: conventional casting (Cgroup), direct metal laser sintering (DMLS-group), micro-stereolithography/casting combination (µSLA-group), and computer-aided milling (M-group) (n = 10). The internal and marginal discrepancies at various reference points were determined via digital microscopy. Analysis of variance (ANOVA) and Tukey’s multiple comparisons tests were used for statistical analysis (p=0.05). The marginal and cervical discrepancies of the C-group were similar to those of the M-group (p>0.05) and better than those of the µSLA-group (p<0.05). The marginal and internal discrepancies of all groups were within clinically acceptable limits, but further improvements in the µSLA and DMLS techniques may be required prior to clinical implementation.

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Dr. Suleyman Cagatay Dayan§
(DDS, PhD)

Dr. Burim Kiseri^

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(DDS, PhD)

Dr. Burc Gencel§
(DDS, PhD)

Dr. Aysegul Kurt*

Address for Correspondence
Email: kurt.aysegul@gmail.com

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Dr. Aysegul Kurt*

is

(DDS, PhD)

* Trakya University, Faculty of Dentistry,
Department of Prosthodontics, Edirne, Turkey
Program of Dental Technicians, Istanbul
University, Istanbul, Turkey

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Evaluation of the Internal
and Marginal Discrepancies
of Co-Cr Metal Copings
Prepared via CAD/CAM and
Conventional Casting

©

^ Department of Prosthodontics, UBT College,
Faculty of Dentistry, Pristina, Kosovo

Conventional metal ceramic restorations have been used to prepare fixed prostheses for several decades and afford satisfactory clinical outcomes;1,2 thus, they remain the primary treatment choice in most cases. Basically, a ceramic material is fused to a metal substructure prepared either via casting or digitally enhanced metal-ceramic restoration.

The basic procedure for conventional casting is as follows: the invested wax pattern of the substructure is burnt out to create a heat-resistant chamber receiving a melted alloy to complete the casting.3 This method is accurate only when high-quality hardware and carefully matched materials are available for use by experienced operators; furthermore, this is a time-consuming multistep procedure.4 Advances in digital technology, including computer-aided design/computer-aided manufacturing (CAD/CAM), have revolutionised dental laboratories. CAD affords rapid high-precision modelling, simple and rapid design modification, and repeated use of the same design.5,6 CAM involves two production methods: subtractive and additive. Subtractive CAM requires precise milling of blocks of material.7 Metal copings may be made via subtractive manufacturing using soft metal blocks; this method aims to deal with stress formation in milling equipment during

Received: 15.09.2018 Accepted: 05.12.2018

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