title: Fracture load of tooth-implant-retained zirconia ceramic fixed dental prostheses: effect of span length and preparation design.
abstract: OBJECTIVE
  Evaluation of the effect of different span length and preparation designs on the fracture load of tooth-implant-supported fixed dental prostheses (TIFDPs) manufactured from yttrium-stabilized zirconia frameworks.
  
  
  METHODS
  Forty-eight TIFDPs were manufactured using a CAD/CAM system and veneered with a press ceramic. Rigidly mounted implants (SLA, diameter 4.1 mm, length 10 mm) in the molar region with a titanium abutment were embedded in PMMA bases pairwise with premolars. All premolars were covered with heat-shrink tubing to simulate physiological tooth mobility. Six different test groups were prepared (a) differing in the preparation design of the premolar (inlay [i]; crown [c]), (b) the material of the premolar (metal [m]; natural human [h]) and (c) the length of the TIFDPs (3-unit [3]; 4-unit [4]). All TIFDPs underwent thermomechanical loading (TCML) (10,000 × 6.5°/60°; 6 × 10(5) × 50 N). The load to fracture (N) was measured and fracture sites were evaluated macroscopically.
  
  
  RESULTS
  None of the restorations failed during TCML. The mean fracture loads (standard deviations) were 1,522 N (249) for the 3-unit, inlay-retained TIFDPs on a metal abutment tooth (3-im), 1,910 N (165) for the 3-cm group, 1,049 N (183) for group 4-im, 1,274 N (282) for group 4-cm, 1,229 N (174) for group 4-ih and 911 N (205) for group 4-ch. Initial damages within the veneering ceramic occurred before the final failure of the restoration. The corresponding loads were 24-52% lower than the fracture load values.
  
  
  CONCLUSIONS
  All restorations tested could withstand the mastication forces expected. Fracture-load values for 3- and 4-unit inlay-crown and crown-crown-retained TIFDPs should spur further clinical investigation.
authors.affiliation: Department of Prosthodontics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Gabbert
authors.affiliation: Department of Prosthodontics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Efstathios
authors.initials: E
authors.lastname: Karatzogiannis
authors.affiliation: Department of Prosthodontics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Ohlmann
authors.affiliation: Department of Prosthodontics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Schmitter
authors.affiliation: Department of Prosthodontics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Karl
authors.affiliation: Department of Prosthodontics, University of Heidelberg, Heidelberg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Rammelsberg
mesh_terms: D001732:Bite Force; D002484:Cementation; D017076:Computer-Aided Design; D000044:Dental Abutments; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003830:Denture, Partial, Fixed; D006801:Humans; D007576:Jaw, Edentulous, Partially / Q000534:rehabilitation*; D008422:Materials Testing; D003765:Models, Dental; D018709:Statistics, Nonparametric; D014025:Titanium; D019415:Torque; D015019:Yttrium / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003764:Dental Materials; D003776:Dental Porcelain; D015019:Yttrium; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide