J Korean Acad Prosthodont.  2019 Jul;57(3):211-218. 10.4047/jkap.2019.57.3.211.

Comparative evaluation of marginal and internal fit of metal copings fabricated by various CAD/CAM methods

• Jeong SJ
• Cho HW
• Jung JH
• Kim JM
• Kim YL

• KMID: 2453774
• DOI: http://doi.org/10.4047/jkap.2019.57.3.211

Abstract

PURPOSE
The purpose of the present study was to compare the accuracy of four different metal copings fabricated by CAD/CAM technology and to evaluate clinical effectiveness.
MATERIALS AND METHODS
Composite resin tooth of the maxillary central incisor was prepared for a metal ceramic crown and duplicated metal die was fabricated. Then scan the metal die for 12 times to obtain STL files using a confocal microscopy type oral scanner. Metal copings with a thickness of 0.5 mm and a cement space of 50 µm were designed on a CAD program. The Co-Cr metal copings were fabricated by the following four methods: Wax pattern milling & Casting (WM), Resin pattern 3D Printing & casting (RP), Milling & Sintering (MS), Selective laser melting (SLM). Silicone replica technique was used to measure marginal and internal discrepancies. The data was statistically analyzed with One-way analysis of variance and appropriate post hoc test (Scheffe test) (α=.05).
RESULTS
Mean marginal discrepancy was significantly smaller in the Group WM (27.66 ± 9.85 µm) and Group MS (28.88 ± 10.13 µm) than in the Group RP (38.09 ± 11.14 µm). Mean cervical discrepancy was significantly smaller in the Group MS than in the Group RP. Mean axial discrepancy was significantly smaller in the Group WM and Group MS then in the Group RP and Group SLM. Mean incisal discrepancies was significantly smaller in the Group RP than in all other groups.
CONCLUSION
The marginal and axial discrepancies of the Co-Cr coping fabricated by the Wax pattern milling and Milling/Sintering method were better than those of the other groups. The marginal, cervical and axial fit of Co-Cr copings in all groups are within a clinically acceptable range.

Keyword

CAD/CAM; Crowns; Dental marginal adaptation; Dental internal adaptations

MeSH Terms

Ceramics
Crowns
Dental Marginal Adaptation
Freezing
Incisor
Methods*
Microscopy, Confocal
Printing, Three-Dimensional
Replica Techniques
Silicon
Silicones
Tooth
Treatment Outcome
Silicon
Silicones

Figure

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  Fig. 1 Standardized model was fabricated with casting Ni-Cr alloy. (A) Labial view of master die for maxillary central incisor, (B) Duplicated metal die.

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  Fig. 2 CAD/CAM metal coping design process. (A) Margin line, (B) 50 µm of virtual cement spacer at 1 mm above the margin, (C) Design of full crown, (D) Completed design of metal coping.

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  Fig. 3 Metal copings fabricated by Selective laser melting (SLM) technique.

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  Fig. 4 (A) Reference points on the mesiodistal plane, (B) Reference points on the labiopalatal plane.

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  Fig. 5 (A) Replica sections were observed at the axial point with a stereomicroscope at × 160 magnification, (B) Replica sections were observed at the marginal and cervical points with a stereomicroscope at × 160 magnification.

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  Fig. 6 Mean and standard deviation of marginal discrepancies of four experimental groups.

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  Fig. 7 Mean and standard deviation of cervical discrepancies of four experimental groups.

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  Fig. 8 Mean and standard deviation of Axial discrepancies of four experimental groups.

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  Fig. 9 Mean and standard deviation of incisal discrepancies of four experimental groups.

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