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Document Type |
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Article In Journal |
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Document Title |
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Effects of acid hydrolysis and mechanical polishing on surface residual stresses of low-fusing dental ceramics Effects of acid hydrolysis and mechanical polishing on surface residual stresses of low-fusing dental ceramics |
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Document Language |
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English |
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Abstract |
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STATEMENT OF PROBLEM: Cracks may arise in a ceramic restorative
material over time, resulting in sudden fractures at stresses well below the
yield stress. PURPOSE: This study evaluated by means of indentation
technique the effects of acid hyd rolysis and mechanical polishing on the
surface residual stresses of low-fusing ceramic materials. MATERIAL AND
METHODS: A total of 64 ceramic bars were formed to produce 4 groups of
16 bars each for 4 ceramic materials (Duceram-LFC Dentin, Duceram-LFC
Enamel, Finesse Dentin, and Finesse Enamel). Four surface-treatment groups
(n=4) were then formed for each of the 4 materials. The 4 surface treatments
were control (autoglaze), hydrolysis, glaze/polish, and polish/glaze. A Vickers
indenter contacted the Duceram-LFC specimens with a 5-N load and the
Finesse specimens with a 3-N load for 10 seconds. Scanning electron
microscope (SEM) was used to study surface texture before and after
hydrolysis and polishing. Differences in mean crack lengths were analyzed
with 1-way analysis of variance and least significant difference test
(alpha=.05.) RESULTS: SEM showed obvious surface flaws as a result of
hydrolysis on Duceram-LFC Enamel and Dentin specimens. However,
statistical analysis of the resulting crack lengths revealed no significant
differences between values for the control groups (58.16 +/- 3.88) (53.53 +/-
2.67) and hydrolysis groups (57.11 +/- 4.09) (54.54 +/- 3.15) for Enamel
(P=.081) and Dentin (P=.093) respectively. When comparing polished groups
and nonpolished groups, the mean crack lengths were significantly shorter for
polished specimens of Duceram-LFC Enamel (53.76 +/- 3.17), Finesse
Enamel (40.56 +/- 3.31), and Finesse Dentin (39.76 +/- 3.81) porcelains
compared with their control groups (58.16 +/- 3.88) (43.54 +/- 4.12) (41.19 +/-
3.47), respectively (P<.0001). The mean crack lengths were significantly
longer for polished specimens of Duceram-LFC Dentin (59.16 +/- 3.52)
porcelain compared with the control group (53.53 +/- 2.67) (P<.0001).
CONCLUSION: Within the limitations of this study, hydrolysis did not
improve surface residual stresses of Duceram-LFC and Finesse ceramic
materials. Mechanical polishing improved surface residual stresses of all
materials tested, except Duceram-LFC Dentin porcelain. |
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ISSN |
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0 |
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Journal Name |
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J Prosthet Dent |
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Volume |
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90 |
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Issue Number |
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2 |
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Publishing Year |
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2003 AH
2003 AD |
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Article Type |
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Article |
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Added Date |
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Friday, January 4, 2008 |
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Researchers
| ياسر الخياري | Alkhiary, Yaser | Investigator | Doctorate | YALKHIARY@Kau.edu.sa |
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