Lifetime prediction of veneered versus monolithic lithium disilicate crowns loaded on marginal ridges

Vitor Guarçoni de Paula, Gerson Bonfante, Fabio C. Lorenzoni, Paulo G. Coelho, Leonardo Rigoldi Bonjardim, Vinicius P. Fardin, Estevam A. Bonfante

Research output: Contribution to journalArticlepeer-review

Abstract

Objective: To evaluate the probability of survival of monolithic and porcelain veneered lithium disilicate crowns comprised by a conventional or modified core when loaded on marginal ridges. Methods: Lithium disilicate molar crowns (n = 30) were fabricated to be tested at mesial and distal marginal ridges and were divided as follows: (1) bilayered crowns with even-thickness 0.5 mm framework (Bi-EV); (2) bilayered crowns with modified core design (Bi-M-lingual collar connected to proximal struts), and: (3) monolithic crowns (MON). After adhesively cemented onto composite-resin prepared replicas, mesial and distal marginal ridges of each crown (n = 20) were individually cyclic loaded in water (30–300 N) with a ceramic indenter at 2 Hz until fracture. The 2-parameter Weibull was used to calculate the probability of survival (reliability) (90% 2-sided confidence bounds) at 1, 2, and 3 million cycles and mean life. Results: The reliability at 1 and 2 million cycles was significantly higher for MON (47% and 19%) compared to Bi-EV (20% and 4%) and Bi-M (17% and 2%). No statistical difference was found between bilayered groups. Only the MON group presented crown survival (7%) at 3 million cycles. The mean life was highest for MON (1.73E + 06), lowest for Bi-M (573,384) and intermediate for Bi-E (619,774). Fractographic analysis showed that the fracture originated at the occlusal surface. The highest reliability was found for MON crowns. The modified framework design did not improve the fatigue life of crowns. Significance: Monolithic lithium disilicate crowns presented higher probability of survival and mean life than bilayered crowns with modified framework design when loaded at marginal ridges.

Original languageEnglish (US)
Pages (from-to)511-522
Number of pages12
JournalDental Materials
Volume35
Issue number3
DOIs
StatePublished - Mar 2019

Keywords

  • Crowns
  • Fatigue
  • Lithium disilicate
  • Porcelain

ASJC Scopus subject areas

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

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