title: Influence of artificial aging on the load-bearing capability of straight or angulated zirconia abutments in implant/tooth-supported fixed partial dentures.
abstract: OBJECTIVE
  The aim of the study was to evaluate the influence of artificial aging on the fracture behavior of straight and angulated zirconia implant abutments used in ZirDesign (Astra Tech) implant/tooth-supported fixed partial dentures (FPDs) in the maxilla.
  
  
  METHODS
  Four different test groups (n = 8) representing anterior implant/tooth-supported FPDs were prepared. Groups 1 and 2 simulated a clinical situation with an ideal implant position (maxillary left central incisor) from a prosthetic point of view, which allowed for the use of a straight, prefabricated zirconia abutment. Groups 3 and 4 simulated a situation with a compromised implant position that required an angulated (20-degree) abutment. OsseoSpeed implants (4.5 3 13 mm, Astra Tech) as well as metal tooth analogs (maxillary right lateral incisor) with simulated periodontal mobility were mounted in polymethyl methacrylate. The FPDs (chromium-cobalt alloy) were cemented with glass ionomer. Groups 2 and 4 were thermomechanically loaded and subjected to static loading until failure. Statistical analysis of force data at the fracture site was performed using nonparametric tests.
  
  
  RESULTS
  All samples survived thermomechanical loading. Artificial aging did not lead to a significant decrease in load-bearing capacity in either the straight abutments or the angulated abutments. The restorations that used angulated abutments exhibited higher fracture loads than the restorations with straight abutments (group 1: 209.13 ± 39.11 N; group 2: 233.63 ± 30.68 N; group 3: 324.62 ± 108.07 N; group 4: 361.75 ± 73.82 N). This difference in load-bearing performance was statistically significant, both with and without artificial aging. All abutment fractures occurred below the implant shoulder.
  
  
  CONCLUSIONS
  Compensation for angulated implant positions with an angulated zirconia abutment is possible without reducing the load-bearing capacity of implant/tooth-supported anterior FPDs.
authors.affiliation: Department of Prosthetic Dentistry and Dental Materials Sciences, Dental School and Clinics, Saarland University, Homburg/Saar, Germany. zmkfnot@uniklinikum-saarland.de
authors.forename: Frank P
authors.initials: FP
authors.lastname: Nothdurft
authors.forename: Klaus E
authors.initials: KE
authors.lastname: Doppler
authors.forename: Kurt J
authors.initials: KJ
authors.lastname: Erdelt
authors.forename: Andreas W
authors.initials: AW
authors.lastname: Knauber
authors.forename: Peter R
authors.initials: PR
authors.lastname: Pospiech
mesh_terms: D000044:Dental Abutments; D003758:Dental Implantation, Endosseous; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003830:Denture, Partial, Fixed; D018709:Statistics, Nonparametric; D013997:Time Factors; D015040:Zirconium
chemical_list: D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide