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Influence of Contraction Mismatch and Cooling Rate on Flexural Failure of PFM Systems

Department of Prosthodontics, College of Dentistry, University of Florida, Gainesville, Florida 32610

K.J. Anusavice

Department of Dental Biomaterials, College of Dentistry, University of Florida, Gainesville, Florida 32610

P.H. Dehoff

Department of Mechanical Engineering and Engineering Science, University of North Carolina at Charlotte, Charlotte, North Carolina 28223

R.B. Lee

Department of Dental Biomaterials, College of Dentistry, University of Florida, Gainesville, Florida 32610

B. Hojjatie

Department of Dental Biomaterials, College of Dentistry, University of Florida, Gainesville, Florida 32610

The interactive influence of cooling rate and the sign and magnitude of thermal contraction difference between metals and ceramic veneers on bond strength have not been extensively analyzed, although numerous bond-test studies have been reported during the past two decades. A previous analytical study of residual incompatibility stress in bond-test specimens indicated that bond strength values may be of relatively little value if the residual stress state of the metal-ceramic specimens is not considered. The objective of this study was to determine the influence of cooling rate and contraction mismatch on the flexural failure resistance of metal opaque-porcelain strips.

Specimens were subjected to four-point loading in an Instron testing machine until crack initiation occurred at the metal-ceramic interface. The residual stress states in the ceramic region were estimated from finite element stress analyses of the bond-test specimens by use of dilatometry data obtained at the cooling rate of 3°Clmin. The total stress induced from the residual stress and the applied flexural load was also determined for these specimens. Statistical analyses of the experimental data revealed that the slowly cooled specimens exhibited a significantly lower (p < 0.05) flexural strength compared with rapidly cooled specimens. Regardless of the cooling technique, metal-ceramic specimens with a negative thermal contraction difference (_m - _p < 0) failed at significantly lower (p < 0.05) flexural loads than did specimens with a positive thermal contraction difference.

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Journal of Dental Research, Vol. 67, No. 1, 61-65 (1988)
DOI: 10.1177/00220345880670011201


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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Coffey, J.P. Articles by Hojjatie, B. Search for Related Content PubMed PubMed Citation Articles by Coffey, J.P. Articles by Hojjatie, B. Pubmed/NCBI databases Substance via MeSH Social Bookmarking                         What's this?