Dental Materials
Volume 26, Issue 5 , Pages 483-490, May 2010

Mechanical strength and subcritical crack growth under wet cyclic loading of glass-infiltrated dental ceramics

  • Susana M. Salazar Marocho

      Affiliations

    • Department of Dental Materials and Prosthodontics, São Paulo State University-UNESP, São Paulo, Brazil
    • ,
  • André R. Studart

      Affiliations

    • Complex Materials, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland
    • ,
  • Marco A. Bottino

      Affiliations

    • Department of Dental Materials and Prosthodontics, São Paulo State University-UNESP, São Paulo, Brazil
    • ,
  • Alvaro Della Bona

      Affiliations

    • Dental School, University of Passo Fundo, Passo Fundo, RS, Brazil
    • Corresponding Author InformationCorresponding author at: Rua Uruguai 2001, 401, Passo Fundo, RS 99010-112, Brazil. Tel.: +55 54 3311 5142; fax: +55 54 3316 8403.

Received 24 August 2009; received in revised form 8 December 2009; accepted 8 January 2010.

Abstract 

Objectives

Evaluate the flexural strength (σ) and subcritical crack growth (SCG) under cyclic loading of glass-infiltrated alumina-based (IA, In-Ceram Alumina) and zirconia-reinforced (IZ, In-Ceram Zirconia) ceramics, testing the hypothesis that wet environment influences the SCG of both ceramics when submitted to cyclic loading.

Methods

Bar-shaped specimens of IA (n=45) and IZ (n=45) were fabricated and loaded in three-point bending (3P) in 37°C artificial saliva (IA3P and IZ3P) and cyclic fatigued (F) in dry (D) and wet (W) conditions (IAFD, IAFW, IZFD, IZFW). The initial σ and the number of cycles to fracture were obtained from 3P and F tests, respectively. Data was examined using Weibull statistics. The SCG behavior was described in terms of crack velocity as a function of maximum stress intensity factor (KImax).

Results

The Weibull moduli (m=8) were similar for both ceramics. The characteristic strength (σ0) of IA and IZ was and 466MPa 550MPa, respectively. The wet environment significantly increased the SCG of IZ, whereas a less evident effect was observed for IA. In general, both ceramics were prone to SCG, with crack propagation occurring at KI as low as 43–48% of their critical KI. The highest σ of IZ should lead to longer lifetimes for similar loading conditions.

Significance

Water combined with cyclic loading causes pronounced SCG in IZ and IA materials. The lifetime of dental restorations based on these ceramics is expected to increase by reducing their direct exposure to wet conditions and/or by using high content zirconia ceramics with higher strength.

Keywords: Glass-infiltrated ceramic, Cyclic fatigue, Subcritical crack growth, Strength, Weibull statistics

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PII: S0109-5641(10)00025-4

doi:10.1016/j.dental.2010.01.007

Dental Materials
Volume 26, Issue 5 , Pages 483-490, May 2010

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