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Contact Damage as a Failure Mode During In Vitro Testing
Author(s) -
Harvey Charles K.,
Kelly J. Robert
Publication year - 1996
Publication title -
journal of prosthodontics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.902
H-Index - 60
eISSN - 1532-849X
pISSN - 1059-941X
DOI - 10.1111/j.1532-849x.1996.tb00281.x
Subject(s) - materials science , ceramic , indentation , composite material , contact mechanics , failure mode and effects analysis , glass ceramic , forensic engineering , structural engineering , finite element method , engineering
Purpose The purpose of this study was to identify the failure mode(s) for all‐ceramic crowns tested in vitro and to determine whether measured failure loads in this type of testing would be influenced by indenter radii (a classic Hertzian cone‐crack variable) and specimen thickness. Materials & Methods Fracture surfaces and failure probability data from glass‐ceramic cuspids (50 = n) tested in a previous in vitro study were examined to determine their mode of failure. To further evaluate the failure mode identified for the crowns, 100 ceramic platelets (50 glass‐ceramic, 50 feldspathic porcelain) were loaded to failure beneath spherical indenters (radii, 0.75‐94 mm). Results Glass‐ceramic cuspids failed from blunt contact damage at the point of loading (with Hertzian stress‐state damage evident). Ceramic platelets exhibited failure from either the indentation surface (Hertzian cone‐cracking present) or from the supported surface (ie, mimicking bending failure). Failure‐loads increased with the indenter radius for both failure modes. Failure from blunt contact damage occurred at markedly higher loads than did failure from support‐surface sites. Conclusions Blunt indentation damage was identified as being the failure source for the glass‐ceramic cuspid crowns and a major failure mode for both feldspathic porcelain and glass‐ceramic platelets loaded beneath spherical indenters. This failure mode is not similar to that reported for clinically failed glass‐ceramic crowns. Influential testing variables were contact radius, ceramic thickness, and the surface finish of both the ceramic specimen and test platen.