Fatigue and damage accumulation of veneer porcelain pressed on Y-TZP

Estevam A. Bonfante, Paulo G. Coelho, Petra C. Guess, Van P. Thompson, Nelson R.F.A. Silva

Research output: Contribution to journalArticle

Abstract

Objectives: This study compared the reliability and fracture patterns of zirconia cores veneered with pressable porcelain submitted to either axial or off-axis sliding contact fatigue. Methods: Forty-two Y-TZP plates (12 mm × 12 mm × 0.5 mm) veneered with pressable porcelain (12 mm × 12 mm × 1.2 mm) and adhesively luted to water aged composite resin blocks (12 mm × 12 mm × 4 mm) were stored in water at least 7 days prior to testing. Profiles for step-stress fatigue (ratio 3:2:1) were determined from single load to fracture tests (n = 3). Fatigue loading was delivered on specimen either on axial (n = 18) or off-axis 30° angulation (n = 18) to simulate posterior tooth cusp inclination creating a 0.7 mm slide. Single load and fatigue tests utilized a 6.25 mm diameter WC indenter. Specimens were inspected by means of polarized-light microscope and SEM. Use level probability Weibull curves were plotted with 2-sided 90% confidence bounds (CB) and reliability for missions of 50,000 cycles at 200 N (90% CB) were calculated. Results: The calculated Weibull Beta was 3.34 and 2.47 for axial and off-axis groups, respectively, indicating that fatigue accelerated failure in both loading modes. The reliability data for a mission of 50,000 cycles at 200 N load with 90% CB indicates no difference between loading groups. Deep penetrating cone cracks reaching the core-veneer interface were observed in both groups. Partial cones due to the sliding component were observed along with the cone cracking for the off-axis group. No Y-TZP core fractures were observed. Conclusions: Reliability was not significantly different between axial and off-axis mouth-motion fatigued pressed over Y-TZP cores, but incorporation of sliding resulted in more aggressive damage on the veneer.

Original languageEnglish (US)
Pages (from-to)318-324
Number of pages7
JournalJournal of Dentistry
Volume38
Issue number4
DOIs
StatePublished - Apr 1 2010

    Fingerprint

Keywords

  • All-ceramics
  • Pressable porcelain
  • Reliability
  • Step-stress fatigue
  • Y-TZP
  • Zirconia

ASJC Scopus subject areas

  • Dentistry(all)

Cite this