Interfacial stress in porcelain bodies bonded to metal prosthetic restorations
✍ Scribed by Nielsen, John P. ;Tuccillo, J. J.
- Publisher
- John Wiley and Sons
- Year
- 1972
- Tongue
- English
- Weight
- 616 KB
- Volume
- 6
- Category
- Article
- ISSN
- 0021-9304
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✦ Synopsis
The shear strength developed in a porcelain-gold restoration has been demonstrated by Shell and Nielsen to be approximately 13,000 psi. Leone and Fairhurst using the Shell-Nielsen test and similar materials obtained values ranging from 13,000 to 13,600 psi. Data has been published indicating shear strength values as high as 20,000 psi; presumably the increase is due to the alleviation of notch effects in the Shell-Nielsen specimen.
An important factor called out in the Shell-Nielsen paper, is that for maximum bond strength, weakening factors such as thermal stresses be absent; that is, perfectly matched coefficients of expansion between the porcelain and metal are a prime requisite. Little work has been directed toward determining the degree of bond strength weakening caused by mismatch of the expansion coefficients.
The interfacial shear stress developed in cooling a porcelain-gold restoration, due to expansion coefficient disparity, is the subject of this paper. Results of calculations for the porcelain-gold interfacial shear stress arising from this disparity will be presented.
The theory of stresses generated on heating or cooling of bi-material strips 395 @ 1972 by John Wiley & Sons, Inc.