title: Load-bearing capacity of screw-retained CAD/CAM-produced titanium implant frameworks (I-Bridge®2) before and after cyclic mechanical loading.
abstract: Implant-supported screw-retained fixed dental prostheses (FDPs) produced by CAD/ CAM have been introduced in recent years for the rehabilitation of partial or total endentulous jaws. However, there is a lack of data about the long-term mechanical characteristics.
  
  
  OBJECTIVE
  The aim of this study was to investigate the failure mode and the influence of extended cyclic mechanical loading on the load-bearing capacity of these frameworks.
  
  
  METHODS
  Ten five-unit FDP frameworks simulating a free-end situation in the mandibular jaw were manufactured according to the I-Bridge®2-concept (I-Bridge®2, Biomain AB, Helsingborg, Sweden) and each was screw-retained on three differently angulated Astra Tech implants (30º buccal angulation/0º angulation/30º lingual angulation). One half of the specimens was tested for static load-bearing capacity without any further treatment (control), whereas the other half underwent five million cycles of mechanical loading with 100 N as the upper load limit (test). All specimens were loaded until failure in a universal testing machine with an occlusal force applied at the pontics. Load-displacement curves were recorded and the failure mode was macro- and microscopically analyzed. The statistical analysis was performed using a t-test (p=0.05).
  
  
  RESULTS
  All the specimens survived cyclic mechanical loading and no obvious failure could be observed. Due to the cyclic mechanical loading, the load-bearing capacity decreased from 8,496 N±196 N (control) to 7,592 N±901 N (test). The cyclic mechanical loading did not significantly influence the load-bearing capacity (p=0.060). The failure mode was almost identical in all specimens: large deformations of the framework at the implant connection area were obvious.
  
  
  CONCLUSIONS
  The load-bearing capacity of the I-Bridge®2 frameworks is much higher than the clinically relevant occlusal forces, even with considerably angulated implants. However, the performance under functional loading in vivo depends on additional aspects. Further studies are needed to address these aspects.
authors.affiliation: Clinic for Maxillofacial Surgery, Plastic Surgery, Implant Center, Stuttgart, Germany.
authors.forename: Marc Philipp
authors.initials: MP
authors.lastname: Dittmer
authors.forename: Moritz
authors.initials: M
authors.lastname: Nensa
authors.forename: Meike
authors.initials: M
authors.lastname: Stiesch
authors.forename: Philipp
authors.initials: P
authors.lastname: Kohorst
mesh_terms: D001863:Bone Screws; D017076:Computer-Aided Design; D000044:Dental Abutments; D003764:Dental Materials / Q000737:chemistry; D017267:Dental Prosthesis Design / Q000379:methods*; D019094:Dental Prosthesis, Implant-Supported / Q000379:methods*; D019232:Dental Restoration Failure; D008422:Materials Testing; D012016:Reference Values; D015203:Reproducibility of Results; D014025:Titanium / Q000737:chemistry*; D016474:Weight-Bearing
chemical_list: D003764:Dental Materials; D014025:Titanium
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