Residual stresses in bilayer dental ceramics

Biomaterials. 2005 Jun;26(16):3235-41. doi: 10.1016/j.biomaterials.2004.08.025.

Abstract

It is clinically observed that lithia-disilicate-based all-ceramic fixed partial dentures (FPD) can fail because of the fragmentation of the veneering material. The hypothesis of this study is that the global residual stresses within the surface of those veneered FPDs may be responsible for partial fragmentation of the veneering ceramic. Bilayer and monolithic ceramic composites were prepared using a lithia disilicate based (Li2OSiO2) glass-ceramic core and a glass veneer. A four-step fracture mechanics approach was used to analyze residual stress in bilayered all-ceramic FPDs. We found a statistically significant increase in the mean flexural strengths of bilayer specimens compared with monolithic glass specimens (p < or = 0.05). There was a statistically significant difference between the mean longitudinal and transverse indentation-induced crack sizes in bilayer specimens (p < or = 0.05), which indicates the existence of residual stress. Global residual stresses in the veneer layer, calculated using a fracture mechanics equation, were determined to be responsible for the increased strength and observed chipping, i.e., spallation in bilayer ceramic composites.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Biocompatible Materials / chemistry*
  • Ceramics / chemistry*
  • Dental Porcelain* / chemistry
  • Dental Restoration Failure
  • Dental Veneers*
  • Hot Temperature
  • Materials Testing
  • Membranes, Artificial
  • Temperature
  • Tensile Strength
  • Time Factors
  • X-Ray Diffraction

Substances

  • Biocompatible Materials
  • Membranes, Artificial
  • lithia disilicate
  • Dental Porcelain