J Adv Prosthodont.  2017 Aug;9(4):239-243. 10.4047/jap.2017.9.4.239.

Evaluation of marginal and internal gaps in single and three-unit metal frameworks made by micro-stereolithography

• Kim DY
• Lee HN
• Kim JH
• Kim HY
• Kim WC

• KMID: 2398069
• DOI: http://doi.org/10.4047/jap.2017.9.4.239

Abstract

PURPOSE
The purpose of this study is to compare single and three-unit metal frameworks that are produced by micro-stereolithography.
MATERIALS AND METHODS
Silicone impressions of a selected molar and a premolar were used to make master abutments that were scanned into a stereolithography file. The file was processed with computer aided design software to create single and three-unit designs from which resin frameworks were created using micro-stereolithography. These resin frameworks were subjected to investment, burnout, and casting to fabricate single and three-unit metal ones that were measured under a digital microscope by using the silicone replica technique. The measurements were verified by means of the Mann-Whitney U test (α=.05).
RESULTS
The marginal gap was 101.9 ± 53.4 µm for SM group and 104.3 ± 62.9 µm for TUM group. The measurement of non-pontics in a single metal framework was 93.6 ± 43.9 µm, and that of non-pontics in a three-unit metal framework was 64.9 ± 46.5 µm. The dimension of pontics in a single metal framework was 110.2 ± 61.4 µm, and that of pontics in a three-unit metal framework was 143.7 ± 51.8 µm.
CONCLUSION
The marginal gap was smaller for the single metal framework than for the three-unit one, which requires further improvement before it can be used for clinical purposes.

Keyword

CAD/CAM; Micro-stereolithography; Metal framework; Marginal gap; Internal gap

MeSH Terms

Bicuspid
Computer-Aided Design
Denture, Partial, Fixed
Investments
Molar
Replica Techniques
Silicon
Silicones
Silicon
Silicones

Figure

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  Fig. 1 Flowchart of fabrication processes for single and three-unit metal frameworks.

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  Fig. 2 Dimensions of three-unit master model in metal casting.

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  Fig. 3 Abutment pin base for working model using three-unit master model.

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  Fig. 4 Metal framework fabrication. (A) single metal framework, (B) three-unit metal framework.

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  Fig. 5 Marginal gap measurement analysis using digital microscope (×160 magnification).

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