J Adv Prosthodont.  2017 Jun;9(3):176-181. 10.4047/jap.2017.9.3.176.

Evaluation of marginal and internal gaps of Ni-Cr and Co-Cr alloy copings manufactured by microstereolithography

• Kim DY
• Kim CM
• Kim JH
• Kim HY
• Kim WC

• KMID: 2382603
• DOI: http://doi.org/10.4047/jap.2017.9.3.176

Abstract

PURPOSE
The purpose of this study was to evaluate the marginal and internal gaps of Ni-Cr and Co-Cr copings, fabricated using the dental µ-SLA system.
MATERIALS AND METHODS
Ten study dies were made using a two-step silicone impression with a dental stone (type IV) from the master die of a tooth. Ni-Cr (NC group) and Co-Cr (CC group) alloy copings were designed using a dental scanner, CAD software, resin coping, and casting process. In addition, 10 Ni-Cr alloy copings were manufactured using the lost-wax technique (LW group). The marginal and internal gaps in the 3 groups were measured using a digital microscope (160 ×) with the silicone replica technique, and the obtained data were analyzed using the non-parametric Kruskal-Wallis H test. Post-hoc comparisons were performed using Bonferroni-corrected Mann-Whitney U tests (α=.05).
RESULTS
The mean (±standard deviation) values of the marginal, chamfer, axial wall, and occlusal gaps in the 3 groups were as follows: 81.5±73.8, 98.1±76.1, 87.1±44.8, and 146.8±78.7 µm in the LW group; 76.8±48.0, 141.7±57.1, 80.7±47.5, and 194.69±63.8 µm in the NC group; and 124.2±52.0, 199.5±71.0, 67.1±37.6, and 244.5±58.9 µm in the CC group.
CONCLUSION
The marginal gap in the LW and NC groups were clinically acceptable. Further improvement is needed for CC group to be used clinical practice.

Keyword

Marginal gap; Internal gap; CAD/CAM; Cobalt-chromium

MeSH Terms

Alloys*
Replica Techniques
Silicon
Silicones
Tooth
Alloys
Silicon
Silicones

Figure

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  Fig. 1 Schematic diagram of the experiment.

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  Fig. 2 Master die fabrication in casting.

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  Fig. 3 Schematic diagram of the µ-SLA system principle.

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  Fig. 4 The silicone replica technique.

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  Fig. 5 Measurement point areas of marginal and internal gaps.

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