The strength of sintered and adhesively bonded zirconia/veneer-ceramic bilayers

Anna Karina F Costa, Alexandre Luiz S Borges, Garry James P Fleming, Owen Addison

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20 Citations (Scopus)
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Abstract

Objectives
Recently all-ceramic restorative systems have been introduced that use CAD/CAM technology to fabricate both the Y-TZP core and veneer-ceramic layers. The aim was to identify whether the CAD/CAM approach resulted in more favourable stressing patterns in the veneer-ceramic when compared with a conventionally sintered Y-TZP core/veneer-ceramic.

Methods
Nominally identical Vita VM9 veneer-ceramic disc-shaped specimens (0.7 mm thickness, 12 mm diameter) were fabricated. 20 specimens received a surface coating of resin-cement (Panavia 21); 20 specimens were bonded with the resin-cement to fully sintered Y-TZP (YZ Vita Inceram Vita) discs (0.27 mm thickness, 12 mm diameter). A final series of 20 Y-TZP core/veneer-ceramic specimens were manufactured using a conventional sintering route. Biaxial flexure strength was determined in a ball-on-ring configuration and stress at the fracture origin calculated using multilayer closed-form analytical solutions. Fractography was undertaken using scanning electron microscopy. The experimental test was simulated using Finite Element Analysis. Group mean BFS were compared using a one-way ANOVA and post hoc Tukey tests at a 95% significance level.

Results
Resin cement application resulted in significant strengthening of the veneer-ceramic and further significant strengthening of the veneer-ceramic (p < 0.01) occurred following bonding to the Y-TZP core. The BFS calculated at the failure origin for conventionally sintered specimens was significantly reduced when compared with the adhesively bonded Y-TZP/veneer-ceramic.

Conclusions
Under the test conditions employed adhesive cementation between CAD/CAM produced Y-TZP/veneer-ceramic layers appears to offer the potential to induce more favourable stress states within the veneer-ceramic when compared with conventional sintered manufacturing routes.

Clinical significance
The current investigation suggests that the stressing patterns that arise in all-ceramic restorations fabricated using CAD/CAM for both the core and veneer-ceramic layers differ from those that occur in conventionally sintered bilayer restorations. Further work is required to ascertain whether such differences will translate into improved clinical outcomes.
Original languageEnglish
Pages (from-to)1269-1276
Number of pages8
JournalJournal of Dentistry
Volume42
Issue number10
Early online date15 Aug 2014
DOIs
Publication statusPublished - 1 Oct 2014

Bibliographical note

Copyright © 2014 Elsevier Ltd. All rights reserved.

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