Effects of cementation surface modifications on fracture resistance of zirconia

Dent Mater. 2015 Apr;31(4):435-42. doi: 10.1016/j.dental.2015.01.013. Epub 2015 Feb 14.

Abstract

Objectives: To examine the effects of glass infiltration (GI) and alumina coating (AC) on the indentation flexural load and four-point bending strength of monolithic zirconia.

Methods: Plate-shaped (12 mm × 12 mm × 1.0 mm or 1.5 or 2.0 mm) and bar-shaped (4 mm × 3 mm × 25 mm) monolithic zirconia specimens were fabricated. In addition to monolithic zirconia (group Z), zirconia monoliths were glass-infiltrated or alumina-coated on their tensile surfaces to form groups ZGI and ZAC, respectively. They were also glass-infiltrated on their upper surfaces, and glass-infiltrated or alumina-coated on their lower (tensile) surfaces to make groups ZGI2 and ZAC2, respectively. For comparison, porcelain-veneered zirconia (group PVZ) and monolithic lithium disilicate glass-ceramic (group LiDi) specimens were also fabricated. The plate-shaped specimens were cemented onto a restorative composite base for Hertzian indentation using a tungsten carbide spherical indenter with a radius of 3.2mm. Critical loads for indentation flexural fracture at the zirconia cementation surface were measured. Strengths of bar-shaped specimens were evaluated in four-point bending.

Results: Glass infiltration on zirconia tensile surfaces increased indentation flexural loads by 32% in Hertzian contact and flexural strength by 24% in four-point bending. Alumina coating showed no significant effect on resistance to flexural damage of zirconia. Monolithic zirconia outperformed porcelain-veneered zirconia and monolithic lithium disilicate glass-ceramics in terms of both indentation flexural load and flexural strength.

Significance: While both alumina coating and glass infiltration can be used to effectively modify the cementation surface of zirconia, glass infiltration can further increase the flexural fracture resistance of zirconia.

Keywords: Alumina coating; Ceramic restorative materials; Flexural strength; Graded zirconia; Indentation flexural load; Surface modification; Zirconia.

Publication types

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

MeSH terms

  • Aluminum Oxide / chemistry*
  • Cementation
  • Ceramics / chemistry*
  • Dental Porcelain / chemistry*
  • Dental Restoration Failure*
  • Dental Stress Analysis
  • Materials Testing
  • Surface Properties
  • Tensile Strength
  • Zirconium / chemistry*

Substances

  • lithia disilicate
  • Dental Porcelain
  • Glass ceramics
  • Zirconium
  • Aluminum Oxide
  • zirconium oxide