Residual stress of porcelain-fused to zirconia 3-unit fixed dental prostheses measured by nanoindentation

Vinicius P. Fardin, Estevam A. Bonfante, Paulo G. Coelho, Malvin N. Janal, Nick Tovar, Lukasz Witek, Dimorvan Bordin, Gerson Bonfante

Research output: Contribution to journalArticle

Abstract

Objective: To evaluate the residual stress (nanoindentation based on hardness) of fatigued porcelain-fused to zirconia 3-unit fixed dental prostheses (FDP) with different framework designs. Methods: Twenty maxillary 3-unit FDP replacing second-premolar (pontic) were fabricated with conventional framework-design (even-thickness of 0.5 mm and 9 mm2 connector area) and modified framework-design (thickness of 0.5 mm presenting lingual collar connected to proximal struts and 12 mm2 connector area). Connector marginal ridges were loaded and the fractured and suspended FDPs were divided (n = 3/each) into: (1) Fractured zirconia even-thickness (ZrEvenF); (2) Suspended zirconia even-thickness (ZrEvenS); (3) Fractured zirconia with modified framework (ZrModF); (4) Suspended zirconia with modified framework (ZrModS); (5) Non-fatigued FDP with conventional framework design (Control). The FDPs were nanoindented at 0.03 mm (Region of Interest (ROI) 1), 0.35 mm (ROI 2) and 1.05 mm (ROI 3) distances from porcelain veneer outer surface with peak load 4000 μN. The Linear Mixed Analysis of Variance (ANOVA) Model on ranks and Least Significant Difference Test on ranks (95%) were used. Results: Highest rank hardness values were found for Control group and ZrModS, whereas the lowest values were found in ZrModF. Statistical differences (p = 0.000) were found among all groups except for comparison between ZrModS and Control group (p = 0.371). Hardness between ROIs were statistically significant different (p < 0.001) where ROI 1 presented the lowest values. Significance: Framework-design modification did not influence the residual stress of porcelain-fused to zirconia fatigued 3-unit FDP. Whereas fractured FDPs showed the highest residual stress compared to suspended and control FDPs. Residual stress increased as nanoindented away from framework.

Original languageEnglish (US)
Pages (from-to)260-271
Number of pages12
JournalDental Materials
Volume34
Issue number2
DOIs
StatePublished - Feb 2018

Keywords

  • Fatigue
  • Fixed dental Prostheses
  • Nanoindentation
  • Porcelain
  • Residual stress
  • Zirconia

ASJC Scopus subject areas

  • Materials Science(all)
  • Dentistry(all)
  • Mechanics of Materials

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