title: Chipping fracture resistance of dental CAD/CAM restorative materials: part I--procedures and results.
abstract: OBJECTIVE
  The edge chipping test was used to measure the fracture resistance of CAD/CAM dental restoration ceramics and resin composites.
  
  
  METHODS
  An edge chipping machine was used to evaluate six materials including one feldspathic porcelain, two glass ceramics, a filled resin-composite, a yttria-stabilized zirconia, and a new ceramic-resin composite material. Force versus edge distance data were collected over a broad range of forces and distances. Data were analyzed by several approaches and several chipping resistance parameters were evaluated. The effects of using different indenter types were explored.
  
  
  RESULTS
  The force versus distance trends were usually nonlinear with good fits to a power law equation with exponents usually ranging from 1.2 to 1.9. The order of chipping resistance (from least to greatest) was: feldspathic porcelain and a leucite glass ceramic (which were similar), followed by the lithium disilicate glass ceramic and the two resin composites (which were similar), and finally the zirconia which had the greatest resistance to chipping. Chipping with a Vickers indenter required 28-45% more force than with the sharp conical 120° indenter. The two indenters rank materials approximately the same way. The power law exponents were very similar for the two indenters for a particular material, but the exponents varied with material. The Rockwell C indenter gives different power law trends and rankings.
  
  
  CONCLUSIONS
  Despite the variations in the trends and indenters, simple comparisons between materials can be made by chipping with sharp conical 120° or Vickers indenters at 0.50mm. Broad distance ranges are recommended for trend evaluation.
authors.affiliation: Volpe Research Center, American Dental Association Foundation, Stop 854-6, NIST, Gaithersburg, MD 29899, USA. Electronic address: george.quinn@nist.gov.
authors.forename: G D
authors.initials: GD
authors.lastname: Quinn
authors.affiliation: Volpe Research Center, American Dental Association Foundation, Stop 854-6, NIST, Gaithersburg, MD 29899, USA.
authors.forename: A A
authors.initials: AA
authors.lastname: Giuseppetti
authors.affiliation: Volpe Research Center, American Dental Association Foundation, Stop 854-6, NIST, Gaithersburg, MD 29899, USA.
authors.forename: K H
authors.initials: KH
authors.lastname: Hoffman
mesh_terms: D017076:Computer-Aided Design; D003764:Dental Materials; D003793:Dental Restoration, Permanent; D003799:Dental Stress Analysis; D008422:Materials Testing
chemical_list: D003764:Dental Materials
keywords: CAD/CAM restorative materials; Edge chip; Feldspathic porcelain; Filled resin composite; Fractography; Leucite glass ceramic; Lithium disilicate glass ceramic; Zirconia