title: The effect of fatigue on the shear bond strength of resin bonded to porcelain.
abstract: OBJECTIVE
  The objective of this study was to determine whether fatigue cycling affects the shear bond strength of a resin that is initially strongly bonded to porcelain.
  
  
  METHODS
  Thirty-five disks of a feldspathic/leucite porcelain were fired on a phosphate-bonded investment material. Each disk was etched with hydrofluoric acid and treated with a silane solution and an adhesive. Resin cement composite cylinders were applied to the treated porcelain and light cured. All specimens were stored for 1 week in distilled water at 37 degrees C and then thermocycled for 1000 cycles in water between 2 degrees C and 50 degrees C. Fifteen of the specimens were randomly selected as control specimens. The remaining were subjected to fatigue cycling. A shear load was applied parallel to the bonded surface and cycled in a square wave between 0 and 26 N at 2 Hz for 27,500 cycles. All specimens were fractured in shear at 1.27 mm/min, and the shear bond strength was determined.
  
  
  RESULTS
  Fifteen percent of fatigued specimens and 6.7% of the control specimens showed at least partial adhesive failure. All other specimens in both groups failed cohesively in the porcelain. There was no significant difference in the mean bond strengths of the fatigued and control groups (analysis of covariance, P > .05).
  
  
  CONCLUSIONS
  For the conditions investigated, cyclic fatigue did not reduce the bond strength of this resin/porcelain system.
authors.affiliation: Department of Oral Health Practice, College of Dentistry, Chandler Medical Center, Lexington, KY 40536-0084.
authors.forename: R T
authors.initials: RT
authors.lastname: Williamson
authors.forename: R J
authors.initials: RJ
authors.lastname: Mitchell
authors.forename: L C
authors.initials: LC
authors.lastname: Breeding
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins; D001840:Dental Bonding; D003776:Dental Porcelain; D017269:Dental Prosthesis Repair; D008422:Materials Testing; D016876:Metal Ceramic Alloys; D012821:Silanes; D013501:Surface-Active Agents; D013718:Tensile Strength
chemical_list: D003188:Composite Resins; D016876:Metal Ceramic Alloys; D012821:Silanes; D013501:Surface-Active Agents; D003776:Dental Porcelain