title: The fatigue bond strength of fixed-fixed versus cantilever resin-bonded partial fixed dental prostheses.
abstract: BACKGROUND
  Restorations using posterior resin-bonded partial fixed dental prostheses to replace missing premolar teeth were previously considered to have only variable success. Although 2-unit cantilevered resin-bonded partial fixed dental prostheses have been shown to have similar or improved clinical retention to their 3-unit counterparts, no in vitro evidence supports their use in preference to fixed-fixed designs.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to fatigue load 2 different resin-bonded partial fixed dental prosthesis designs (3-unit fixed-fixed and 2-unit cantilevered) and then compare their bond strengths after loading to failure.
  
  
  METHODS
  Nickel chromium castings with cantilevered (n=10) and fixed-fixed framework designs (n=10) were bonded with a resin cement to stainless-steel tooth dies supported by a simulated periodontal ligament and subjected to cyclic loading (12 000 cycles). The abutment tooth analog was then secured in a universal testing machine, and the framework was loaded axially away from the tooth die until failure. Differences between the bond strengths of the 2 prosthesis designs were analyzed by a Mann-Whitney U test (P<.05).
  
  
  RESULTS
  The bond strengths of the fixed-fixed group (332 N) were lowered by fatigue loading but not the cantilevered group (421 N) (P<.05).
  
  
  CONCLUSIONS
  Three-unit fixed-fixed resin-bonded partial fixed dental prostheses were found to have a lower bond strength than 2-unit cantilevered resin-bonded partial fixed dental prostheses when fatigue loaded.
authors.affiliation: Honorary Clinical Assistant Professor, Discipline of Oral Rehabilitation, The Prince Philip Dental Hospital, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Tsz Leung
authors.initials: TL
authors.lastname: Wong
authors.affiliation: Associate Professor, Discipline of Oral Rehabilitation, The Prince Philip Dental Hospital, The University of Hong Kong, Hong Kong SAR, China. Electronic address: botelho@hkucc.hku.hk.
authors.forename: Michael George
authors.initials: MG
authors.lastname: Botelho
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D001641:Bicuspid; D002858:Chromium Alloys / Q000737:chemistry; D000044:Dental Abutments; D001840:Dental Bonding; D045662:Dental Etching / Q000379:methods; D003799:Dental Stress Analysis / Q000295:instrumentation; D003779:Denture Design; D003781:Denture Retention; D003830:Denture, Partial, Fixed; D016379:Denture, Partial, Fixed, Resin-Bonded; D006801:Humans; D008422:Materials Testing; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D013314:Stress, Mechanical; D013696:Temperature; D013718:Tensile Strength; D014867:Water / Q000737:chemistry
chemical_list: D002858:Chromium Alloys; D019279:Resin Cements; D014867:Water; D000537:Aluminum Oxide