This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted 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 Griggs, J.A. Articles by Anusavice, K.J. Search for Related Content PubMed PubMed Citation Articles by Griggs, J.A. Articles by Anusavice, K.J. Pubmed/NCBI databases Substance via MeSH Social Bookmarking                         What's this?

Effects of Flaw Size and Auto-glaze Treatment on Porcelain Strength

Department of Dental Biomaterials, Box 100446, JHMHSC, University of Florida, Gainesville, Florida 32610-0446

J.Y. Thompson

presently at Department of Operative Dentistry, University of North Carolina, Chapel Hill, North Carolina 27599-7450

K.J. Anusavice

Department of Dental Biomaterials, Box 100446, JHMHSC, University of Florida, Gainesville, Florida 32610-0446

The functional surfaces of porcelain restorations are often ground to adjust occlusion. This removes the surface glaze and introduces flaws. Re-firing the restoration before final placement produces a self-glaze layer on the surface that may reduce the extent of damage caused by grinding. The objectives of this study were to determine whether re-firing after grinding increases the strength of dental porcelain and to determine whether the effectiveness of this treatment was dependent on the initial flaw size. Six groups, each containing 12 disk specimens, were prepared from experimental body porcelain (No. 36, J.F. Jelenko & Co., Armonk, NY). The specimens were fired under vacuum, ground to a thickness of 1 mm with 240-grit SiC abrasive, and polished through 600-grit on the surface to be subjected to tensile stress. Control Group A consisted of 12 non-indented specimens. Flaws were induced in the remaining groups by means of a Vickers indenter under the following loads: 3.9 N (Group B), 7.8 N (Group C), 11.8 N (Group D), 15.7 N (Group E), and 19.6 N (Group F). Following indentation, half of the specimens from each group were re-fired. The flexure strength of each specimen was determined by means of a piston-on-three-ball biaxial fixture. The TTEST procedure of SAS (1985) indicated a significant difference between the mean strength values of glazed and non-glazed specimens in Group E only (p = 0.55, 0.24, 0.13, 0.07, 0.01, and 0.69 for Groups A to F, respectively). ANOVA with the GLM procedure of SAS (1985) revealed that the mean strength values of groups subjected to five indentation loads were not significantly different (p = 0.45 for glazed specimens and p = 1.00 for non-glazed specimens). These findings support those of Fairhurst et al. (1992) for specimens with smaller flaws that were induced by grinding with 1 um abrasive grit. The results of the current study indicate that re-firing of porcelain with large surface flaws does not significantly increase the flexural strength.

Key Words: porcelain • failure • strength • glaze

REFERENCES

• Binns DB (1983). The chemical and physical properties of dental porcelain. In: Dental ceramics, proceedings of the first international symposium on ceramics. McLean JW, editor. Chicago: Quintessence Publishing Co., Inc., pp. 41-82.
• Cook RF, Lawn BR, Dabbs TP, Chantikul P. (1981). Effect of machining damage on the strength of a glass-ceramic. J Am Ceram Soc 64:C121-C122.
• Davidge RW, Green TJ (1968). The strength of two-phase ceramic/glass materials. J Mater Sci 3:629-634.
• Fairhurst CW, Anusavice KJ, Hashinger DT, Ringle RD, Twiggs SW (1980). Thermal expansion of dental alloys and porcelains. J Biomed Mater Res 14:435-446.[Medline] [Order article via Infotrieve]
• Fairhurst CW, Lockwood PE, Ringle RD, Thompson WO (1992). The effect of glaze on porcelain strength. Dent Mater 8:203-207.[Medline] [Order article via Infotrieve]
• Giordano R., Cima M., Pober R. (1995). Effect of surface finish on the flexural strength of feldspathic and aluminous dental ceramics. Int J Prosthodont 8:311-319.[Medline] [Order article via Infotrieve]
• Kazuyuki H., Tomozawa M. (1987). Dynamic fatigue of treated high-silica glass: explanation by crack tip blunting. J Am Ceram Soc 70:377-382.
• Kingery WD, Bowen HK, Uhlmann DR (1976). Introduction to ceramics. 2nd ed. New York: John Wiley & Sons.
• Mackert JR Jr, Evans AL (1991). Effect of cooling rate on leucite volume fraction in dental porcelains. J Dent Res 70:137-139.
• Mackert JR Jr, Rueggeberg FA, Lockwood PE, Evans AL, Thompson WO (1994). Isothermal anneal effect on microcrack density around leucite particles in dental porcelain. J Dent Res 73:1221-1227.
• Marshall DB (1980). An improved biaxial flexure test for ceramics. Am Ceram Soc Bull 59:551-553.
• Mecholsky JJ, Freiman SW, Rice RW ( 1978). Fractographic analysis of ceramics. In: Fractography in failure analysis, ASTM STP 645. Strauss BM, Cullen WH, editors. Philadelphia: American Society for Testing and Materials, pp. 363-379.
• SAS Institute (1985). SAS user's guide: statistics. 5th ed. Cary, NC: SAS Institute Inc.
• Wachtman JB Jr, Capps W., Mandel J. (1972). Biaxial flexure tests of ceramic substrates. J Mater 7:188-194.

Journal of Dental Research, Vol. 75, No. 6, 1414-1417 (1996)
DOI: 10.1177/00220345960750061301


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				B. Kukiattrakoon and B. Samruajbenjakul Shear bond strength of ceramic brackets with various base designs bonded to aluminous and fluorapatite ceramics Eur J Orthod, October 1, 2009; (2009) cjp055v1. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted 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 Griggs, J.A. Articles by Anusavice, K.J. Search for Related Content PubMed PubMed Citation Articles by Griggs, J.A. Articles by Anusavice, K.J. Pubmed/NCBI databases Substance via MeSH Social Bookmarking                         What's this?