IADR Abstract Archives

How can zirconia-based restorations be improved? – Results from laboratory studies

Objective: This investigation sought to identify the basis of chipping of porcelain veneering materials on zirconia based restorations, which have opened up novel opportunities for clinicians involved in major crown and bridge cases, because of their excellent mechanical, aesthetic and biocompatibility properties. However over the past few years there have been increasing reports of chipping problems of the veneering porcelain, far in excess of traditional porcelain fused to metal systems.

Methods: The thermo-elastic basis for residual stresses and the influence of cooling rate and specimen size will be considered. Zirconia and alumina plates 10 by 20 mm and 0.6 mm thick veneered with appropriate porcelains (e.max Ceram, IvoclarVivadent) and (VM7, Vita Zahnfabrik) of various thicknesses (0.5 to 2.5 mm) and subjected to different cooling rates were investigated. Vickers indentations from 5 to 30 N were placed on the surface of veneering porcelain and the size of the cracks measured.

Results: Length of radial cracks were smaller for rapidly cooled specimens for the porcelain on both alumina and zirconia copings indicative of surface compressive residual stresses. Only for the porcelain fused to the rapidly cooled zirconia coping samples was unstable cracking within the veneering porcelain observed.

Conclusion: The results are interpreted in terms of the thermo-elastic analysis developed. Suggestions to improve processing of zirconia based restorations by technicians and adjustment procedures by clinicians to minimise chipping are also considered.


Continental European, Israeli, Scandinavian Divisions Meeting
2009 Continental European, Israeli, Scandinavian Divisions Meeting (Munich, Germany)
Munich Germany
2009
13
Symposium
  • Swain, Michael V.  ( University of Otago, Dunedin, N/A, New Zealand )
    • Symposium
    Do Zirconia-based Restorations Chip more often than Metal-based Restorations - Perception versus Evidence
    09/10/2009