Adaptability of zirconia core fabricated by cold isostatic pressing

Yoon-Jeong Seo; Kwi-Dug Yun; Kim Hyun-Seung; Sang-Won Park

doi:10.4047/jkap.2010.48.2.143

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Seo, Yun, Hyun-Seung, and Park: Adaptability of zirconia core fabricated by cold isostatic pressing

ORIGINAL ARTICLE

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

Published online: 18 December 2010

DOI: https://doi.org/10.4047/jkap.2010.48.2.143

Adaptability of zirconia core fabricated by cold isostatic pressing

Yoon-Jeong Seo, MSD¹, Kwi-Dug Yun, DDS, MSD¹, Kim Hyun-Seung, PhD², Sang-Won Park, DDS, MSD, PhD^1,^∗

^¹Department of Prosthodontics, School of Dentistry, Chonnam National University, Gwangju, Korea

^²Kuwotech Co. Ltd., Gwangju, Korea

∗Corresponding Author: Sang-Won Park Department of Prosthodontics, School of Dentistry, Chonnam National University, 77 Yongbong-Ro, Buk-gu, Gwang-Ju, 500-757, Korea +82 62 530 5638: e-mail, psw320@chonnam.ac.kr

Received 1 April 20108 April 2010 Accepted 14 April 2010

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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 1040℃ and the final sintering was performed at 1450℃. The Kavo Everest ZS blank^® (KaVo, Biberach/ Riβ.) 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^®, Biberach/ Riβ.). 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^®) at 30 ×. 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 μ m) fabricated from CNU blocks showed significantly smaller than that of the cores of Kavo blocks (36.84 ± 7.18 μ m) (P < .05). The internal gaps of the porcelain veneered crowns (32.23 ± 6.33 μ m) were larger than those of the other two groups (37.57 ± 6.81 μ m and 38.14 ± 6.81 μ m).

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. (J Korean Acad Prosthodont 2010;48:143-50)

Keywords: Core, Cold isostatic pressing, Marginal fit, Shrinkage, Zirconia

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Fig. 1.

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

Fig. 2.

Diagram of prepared tooth.

Fig. 3.

Design of zirconia core by CAD / CAM system.

Fig. 4.

Firing schedule of the post sintering.

Fig. 5.

Measuring points of specimen.

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).

Fig. 7.

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

Table I.

Experimental groups of specimens

Group	Material	Specimens
Group I	Kavo Everest block	Core (n = 7)
Group II Group III	New zirconia block	Core (n = 7) Core + Porcelain (n = 7)

Table II.

Firing schedule of the veneering porcelain

	Base temp	Heat rate	Final temp	Holding time	Cool time
	(℃)	(℃/min)	(℃)	(min)	(min)
Shade Base	600	50	1030	1.00	4.00
1^st Body	600	45	960	1.00	4.00
2^nd Body	600	45	960	1.00	4.00

Table III.

Linear sintering shrinkage of CNU block

Shrinkage			Mean
Block 1	19.02	19.00	18.97	18.99
Block 2	19.06	19.02	18.99	19.02
Block 3	19.02	19.00	19.01	19.01
Total				19.00 (%)

Table IV.

Mean and standard deviation of marginal, internal and occlusal gaps (Unit: μ m)

		Code
		Group I	Group II	Group III
Marginal gap	B	32.08 (5.00)	28.69 (5.05)	28.13 (5.13)
	L	38.43 (7.24)	28.57 (5.94)	26.01 (2.56)
	M	38.44 (6.58)	33.32 (8.46)	28.96 (5.53)
	D	38.44 (9.93)	28.21 (6.90)	25.70 (3.83)
	mean	36.84 (7.18)	29.67 (6.58)	27.20 (4.15)
Internal gap	B	45.79 (8.09)	33.91 (5.91)	31.23 (6.50)
	L	41.51 (8.35)	38.22 (5.01)	33.86 (8.59)
	M	40.75 (5.48)	42.16 (10.82)	33.02 (7.34)
	D	37.57 (5.31)	38.27 (6.12)	30.82 (2.90)
	mean	37.57 (6.81)	38.14 (6.96)	32.23 (6.33)
Occlusal gap	B	48.28 (6.92)	43.34 (5.00)	36.11 (5.06)
	L	45.78 (8.25)	48.44 (4.81)	35.94 (7.96)
	M	42.90 (8.14)	50.87 (7.78)	37.51 (6.41)
	D	44.85 (7.79)	47.70 (3.10)	36.51 (5.48)
	mean	45.45 (7.77)	47.58 (5.17)	43.83 (5.89)

B: Buccal, L: Lingual, M: Mesial, D: Distal

Table V.

Own-way Anova test for marginal gap

Sum of squares	DF	Mean squares	F	P
Between Groups 1147.043 Within Groups 3801.152	2 81	573.521 46.928	12.221	.000
Total 4948.195	83

Table VI.

Own-way Anova test for Internal gap

Sum of squares	DF	Mean squares	F	P
Between Groups 1211.159 Within Groups 4626.659	2 81	605.580 57.119	10.602	.000
Total 5837.818	83

Table VII.

Own-way Anova test for Occlusal gap

Sum of squares	DF	Mean squares	F	P
Between Groups 1930.796 Within Groups 3971.488	2 81	965.398 49.031	19.69	.000
Total 5902.284	83

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