title: Implant-abutment interface design affects fatigue and fracture strength of implants.
abstract: OBJECTIVE
  Failures of implant-abutment connections are relatively frequent clinical problems. The aim of this study was to evaluate the influence of long-term dynamic loading on the fracture strength of different implant-abutment connections.
  
  
  METHODS
  Six implant systems were tested: two systems with external connections (Brånemark, Compress) and four systems with internal connections (Frialit-2, Replace-Select, Camlog, Screw-Vent). Fracture strength was tested in two subgroups for each system: one subgroup with (dyn) and the other without prior dynamic loading (contr). Each subgroup consisted of eight specimens with standard implant-abutment combinations for single molar crowns. Dynamic loading was performed in a two-axis chewing simulator with 1,200,000 load cycles at 120 N.
  
  
  RESULTS
  Median fracture strengths in Newton (N) and 25th and 75th percentiles [in brackets] were: Brånemark: dyn=729 [0;802]/contr=782 [771;811], Frialit-2: dyn=0 [0;611]/contr=887 [798;941], Replace-Select: dyn=1439 [1403;1465]/contr=1542 [1466;1623], Camlog: dyn=1482 [1394;1544]/contr=1467 [1394;1598], Screw-Vent: dyn=0 [0;526]/contr=780 [762;847] and Compress: dyn=818[0;917]/contr=1008 [983;1028]. In some dyn subgroups, failures of the implant-abutment connection occurred already during dynamic loading: three specimens of the Brånemark and Compress groups and six specimens of the Screw-Vent and the Frialit-2 groups failed during dynamic loading. Statistically significant differences (P< or =0.05) in fracture strength could be found between groups with different connection designs.
  
  
  CONCLUSIONS
  Implant systems with long internal tube-in-tube connections and cam-slot fixation showed advantages with regard to longevity and fracture strength compared with systems with shorter internal or external connection designs.
authors.affiliation: Department of Prosthodontics, RWTH Aachen University, Aachen, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Steinebrunner
authors.forename: Stefan
authors.initials: S
authors.lastname: Wolfart
authors.forename: Klaus
authors.initials: K
authors.lastname: Ludwig
authors.forename: Matthias
authors.initials: M
authors.lastname: Kern
mesh_terms: D000044:Dental Abutments; D003758:Dental Implantation, Endosseous; D019250:Dental Implants, Single-Tooth; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention / Q000295:instrumentation; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D006801:Humans; D008409:Mastication; D008422:Materials Testing; D033081:Shear Strength; D018709:Statistics, Nonparametric; D013314:Stress, Mechanical; D016019:Survival Analysis