title: Fatigue resistance of two implant/abutment joint designs.
abstract: BACKGROUND
  Because of reported mechanical failures, alternative implant system components with suggested optimized strength have been manufactured. However, the endurance of these products has not been well investigated.
  
  
  OBJECTIVE
  This study was designed to assess the effect of joint design on the fatigue strength and failure mode of 2 single-tooth implant systems: Brånemark and ITI, in which a hex mediated-butt joint and 8-degree internal conical implant/abutment interface are used, respectively.
  
  
  METHODS
  Seven 10-mm implants from each implant system were embedded to a depth of 7 mm in cylindrical acrylic resin blocks. CeraOne and Solid abutments with cement-retained castings were assembled to the Brånemark and ITI implants, respectively. The assembled units were mounted in a lever-type-testing machine that was equipped with an automatic counting device and shutoff sensors, enabling the recording of the number of cycles till failure. A cyclic load of 100 N was applied perpendicular to the long axis of the assemblies at a rate of 75 cycles/min. To investigate specimen resistance to fatigue during 6 years of simulated function, a target of 1,800,000 cycles was defined. Specimen preparation and testing was performed by the same operator. The association of the joint design with the occurrence of failure was verified by Fisher's exact probability test (P<.05).
  
  
  RESULTS
  For the Brånemark group, the gold alloy abutment screw in all specimens fractured between 1,178,023 and 1,733,526 cycles with a standard deviation of 224,477 cycles. For the ITI group, all specimens had no failure until 1,800,000 cycles. Statistical analysis showed a highly significant difference between the 2 groups (P=.000582).
  
  
  CONCLUSIONS
  Within the limitations of this in vitro study, the effect of joint design on the fatigue strength and failure mode of the ITI single tooth implant system was significantly better (P>.001) than the Brånemark single-tooth implant system tested.
authors.affiliation: Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan. ameen@dent.niigata-u.ac.jp
authors.forename: Ameen
authors.initials: A
authors.lastname: Khraisat
authors.forename: Roxana
authors.initials: R
authors.lastname: Stegaroiu
authors.forename: Shuichi
authors.initials: S
authors.lastname: Nomura
authors.forename: Osamu
authors.initials: O
authors.lastname: Miyakawa
mesh_terms: D002484:Cementation; D000044:Dental Abutments; D019250:Dental Implants, Single-Tooth; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011336:Probability; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry; D019415:Torque; D016474:Weight-Bearing; D015036:Zinc Phosphate Cement / Q000737:chemistry
chemical_list: D006047:Gold Alloys; D015036:Zinc Phosphate Cement; D014025:Titanium