Dental Materials
Volume 25, Issue 5 , Pages 634-640, May 2009

Failure analysis of clinically failed all-ceramic fixed partial dentures using fractal geometry

  • Panida Bulpakdi

      Affiliations

    • Department of Restorative Dentistry, Indiana University, School of Dentistry, Indianapolis, IN, USA
    • ,
  • Burak Taskonak

      Affiliations

    • Department of Restorative Dentistry, Indiana University, School of Dentistry, Indianapolis, IN, USA
    • Corresponding Author InformationCorresponding author at: Department of Restorative Dentistry, Division of Dental Biomaterials, Indiana University, School of Dentistry, 1121 W. Michigan St., Indianapolis, IN 46202, USA. Tel.: +1 317 274 3725; fax: +1 317 278 7462.
    • ,
  • Jiahau Yan

      Affiliations

    • Department of Restorative Dentistry, Indiana University, School of Dentistry, Indianapolis, IN, USA
    • ,
  • John J. Mecholsky Jr.

      Affiliations

    • Department of Materials Science and Engineering, College of Engineering, University of Florida, Gainesville, FL, USA

Received 7 May 2008; received in revised form 17 November 2008; accepted 23 November 2008.

Abstract 

Objective

The goal of this study was to test the hypothesis that fracture toughness of the veneers in clinically failed zirconia-based fixed partial dentures (FPDs) is not significantly different from that of the in vitro group and to determine the potential reasons for their failures.

Methods

Fracture toughness values of the veneer layers in clinically failed zirconia core/glass veneer FPDs (n=4) and laboratory prepared glass veneer bar specimens (n=6) were determined using fractal analysis. A modified slit island technique was employed to measure the fractal dimensional increment (D*) of the two studied groups. The fracture toughness (KC) values were estimated using equation , where E is the elastic modulus and ao is a characteristic length parameter. Fracture toughness (KC) values of the specimens calculated using fractal analysis and fractography were statistically compared using a paired t-test.

Results

The average fracture toughness of the veneer in clinically FPDs (0.5±0.05MPam1/2) is not significantly different (p>0.05) from that of the bar specimens (0.6±0.1MPam1/2). The reasons for the early failures in FPDs could be occlusal overloading, stress corrosion, fatigue or improper structure design.

Significance

Fractal analysis is shown to be an alternative analytic tool for clinically failed ceramic restorations, especially for those with fracture origins chipped off during mastication and hence could not be analyzed using other techniques, such as fractography.

Keywords: Fractal analysis, Fractography, Failure, Dental ceramic, Fixed partial denture

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PII: S0109-5641(08)00278-9

doi:10.1016/j.dental.2008.11.007

Dental Materials
Volume 25, Issue 5 , Pages 634-640, May 2009

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