Time-dependent fracture probability of bilayer, lithium-disilicate-based, glass-ceramic, molar crowns as a function of core/veneer thickness ratio and load orientation.

Abstract

UNLABELLED:

Recent reports on bilayer ceramic crown prostheses suggest that fractures of the veneering ceramic represent the most common reason for prosthesis failure.

OBJECTIVE:

The aims of this study were to test the hypotheses that: (1) an increase in core ceramic/veneer ceramic thickness ratio for a crown thickness of 1.6mm reduces the time-dependent fracture probability (Pf) of bilayer crowns with a lithium-disilicate-based glass-ceramic core, and (2) oblique loading, within the central fossa, increases Pf for 1.6-mm-thick crowns compared with vertical loading.

MATERIALS AND METHODS:

Time-dependent fracture probabilities were calculated for 1.6-mm-thick, veneered lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation in the central fossa area. Time-dependent fracture probability analyses were computed by CARES/Life software and finite element analysis, using dynamic fatigue strength data for monolithic discs of a lithium-disilicate glass-ceramic core (Empress 2), and ceramic veneer (Empress 2 Veneer Ceramic).

RESULTS:

Predicted fracture probabilities (Pf) for centrally loaded 1.6-mm-thick bilayer crowns over periods of 1, 5, and 10 years are 1.2%, 2.7%, and 3.5%, respectively, for a core/veneer thickness ratio of 1.0 (0.8mm/0.8mm), and 2.5%, 5.1%, and 7.0%, respectively, for a core/veneer thickness ratio of 0.33 (0.4mm/1.2mm).

CONCLUSION:

CARES/Life results support the proposed crown design and load orientation hypotheses.

SIGNIFICANCE:

The application of dynamic fatigue data, finite element stress analysis, and CARES/Life analysis represent an optimal approach to optimize fixed dental prosthesis designs produced from dental ceramics and to predict time-dependent fracture probabilities of ceramic-based fixed dental prostheses that can minimize the risk for clinical failures.

• Authors: Kenneth J Anusavice, Osama M Jadaan, Josephine F Esquivel-Upshaw
• Journal: Dental materials : official publication of the Academy of Dental Materials (Dent Mater) Vol. 29 Issue 11 Pg. 1132-8 (Nov 2013) ISSN: 1879-0097 [Electronic] England
• PMID: 24060349 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)
• Copyright: Copyright © 2013 Academy of Dental Materials. All rights reserved.

Chemical References

• lithia disilicate
• Dental Porcelain

Topics

• Ceramics
• Crowns
• Dental Porcelain (chemistry)
• Finite Element Analysis
• Glass
• Probability