title: Damage accumulation and fatigue life of particle-abraded ceramics.
abstract: OBJECTIVE
  This investigation compared initial and fatigue strengths of particle-abraded ceramics to those of as-polished alumina and zirconia ceramics in crown-like layer structures.
  
  
  METHODS
  Alumina or zirconia plates bonded to polycarbonate substrates were subjected to single-cycle and multi-cycle contact (fatigue) loading. Cementation surfaces of the ceramic were damaged by controlled particle abrasion, indentation with a sharp diamond at low load, or a blunt indenter at high load. The stresses needed to initiate radial fractures were evaluated.
  
  
  RESULTS
  The strengths of specimens were lowered by fatigue loading. After the equivalent of 1 year of occlusal contacts, the strengths of undamaged specimens degraded to approximately half of their single-cycle values. In particle-abraded specimens, an additional 20% to 30% drop in strength occurred after several hundred load cycles. Particle abrasion damage was approximately equivalent to damage from sharp indentation at low load or blunt indentation at high load.
  
  
  CONCLUSIONS
  Damage from particle abrasion, not necessarily immediately apparent, compromised the fatigue strength of zirconia and alumina ceramics in crown-like structures. In fatigue, small flaws introduced by particle abrasion can outweigh any countervailing strengthening effect from compression associated with surface damage or, in the case of zirconia, with phase transformation.
authors.affiliation: Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, New York 10010, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Brian R
authors.initials: BR
authors.lastname: Lawn
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Malament
authors.forename: P
authors.initials: P
authors.lastname: Van Thompson
authors.forename: E Dianne
authors.initials: ED
authors.lastname: Rekow
mesh_terms: D000537:Aluminum Oxide; D003776:Dental Porcelain; D019554:Dental Restoration Wear; D003799:Dental Stress Analysis; D008422:Materials Testing; D013499:Surface Properties; D015019:Yttrium; D015040:Zirconium
chemical_list: C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; D015019:Yttrium; D015040:Zirconium; D000537:Aluminum Oxide