J Korean Acad Prosthodont.  2010 Apr;48(2):143-150.

Adaptability of zirconia core fabricated by cold isostatic pressing

• Seo YJ
• Yun KD
• Kim HS
• Park SW

Abstract

PURPOSE
The purpose of this study is to fabricate the new zirconia block (CNU block) and to evaluate fit of core and porcelain veneered zirconia crown. MATERIAL AND METHODS: The experimental blocks were fabricated from the commercial ytrria-stabilized zirconia powder (KZ-3YE Type A). The powder was uniaxial pressing and the green bodies were conducted using the Cold Isostatic Pressing. The zirconia blocks were presintered at 1040degrees C and the final sintering was performed at 1450degrees C. The Kavo Everest ZS blank(R) (KaVo, Biberach/Ri beta.) was used as a control group. The linear shrinkage of CNU block and Kavo block were compared. Twenty-one cores for porcelain veneered crowns were fabricated with CAD/CAM system (Everest(R), Biberach/Ribeta.). Group I: seven cores fabricated from Kavo blocks, Group II: seven cores fabricated from CNU blocks, Group III: seven cores from CNU blocks and porcelain veneering for crowns. All specimens were cemented and sectioned into two planes: diagonal and bucco-lingual. The measurement of the marginal, internal, and occlusal fit was carried out using SEM (S-4800(R)) at 30 x. The results were analyzed by one-way ANOVA test.
RESULTS
The linear shrinkage of the CNU block and the KaVo block was 19.00% and 20.09%. The marginal gap of cores (29.67 +/- 6.58 micrometer) fabricated from CNU blocks showed significantly smaller than that of the cores of Kavo blocks (36.84 +/- 7.18 micrometer) (P < .05). The internal gaps of the porcelain veneered crowns (32.23 +/- 6.33 micrometer) were larger than those of the other two groups (37.57 +/- 6.81 micrometer and 38.14 +/- 6.81 micrometer).
CONCLUSION
No statistically significant difference was found in between experimental groups and control group. The experimental groups in marginal gap showed significantly smaller than the control group.

Keyword

Core; Cold isostatic pressing; Marginal fit; Shrinkage; Zirconia

MeSH Terms

Cold Temperature
Crowns
Dental Porcelain
Ethylnitrosourea
Zirconium
Dental Porcelain
Ethylnitrosourea
Zirconium

Figure

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  Fig. 1. Schematic diagram of the single action uniaxial press forming and cold isostatic press forming.

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  Fig. 2. Diagram of prepared tooth.

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  Fig. 3. Design of zirconia core by CAD / CAM system.

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  Fig. 4. Firing schedule of the post sintering.

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  Fig. 5. Measuring points of specimen.

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  Fig. 6. SEM images obtained from sectioned specimens of the three groups. A, B, Control; C, D, Core only; E, F, All ceramic crown (Original magnification ×30).

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  Fig. 7. Comparison of total mean marginal, internal, and occlusal gaps at the three groups.

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