title: A prospective 5-year study of two cast framework alloys for fixed implant-supported mandibular prostheses.
abstract: OBJECTIVE
  A longitudinal 5-year clinical investigation was carried out to compare screw-retained frameworks constructed from two alloys with different mechanical properties, either gold or silver-palladium, supported in the mandible by the Astra Tech implant system.
  
  
  METHODS
  Twenty-six edentulous patients with mandibular implants were divided into two groups: group A was provided with Chicago IV gold alloy superstructures, and group B was provided with Palliag M silver-palladium alloy superstructures. The surgical procedures for placing the mandibular bone implants and the prosthodontic and laboratory techniques for constructing the prostheses were carried out according to standard, well-documented practices. All patients wore conventional maxillary complete dentures. The integrity of prostheses and health of supporting tissues were compared over a 5-year period.
  
  
  RESULTS
  Both materials had similar accuracy of fit and resistance to functional stress, although silver-palladium was technique sensitive and necessitated meticulous laboratory practice to achieve accuracy of casting. Clinical performance of both prostheses was similar, and radiographic assessment showed no statistically significant differences in periimplant bone changes.
  
  
  CONCLUSIONS
  There were no differences in clinical performance and radiographic changes between the two materials. Therefore, silver-palladium alloy may be considered a suitable low-cost substitute for gold alloy for fixed implant-supported prostheses.
authors.affiliation: Department of Prosthetic Dentistry, Dental School, University of Wales College of Medicine, Cardiff, United Kingdom.
authors.forename: William M
authors.initials: WM
authors.lastname: Murphy
authors.forename: Elias G
authors.initials: EG
authors.lastname: Absi
authors.forename: Max C
authors.initials: MC
authors.lastname: Gregory
authors.forename: Keith R
authors.initials: KR
authors.lastname: Williams
mesh_terms: D003722:Dental Alloys; D003735:Dental Casting Technique; D003758:Dental Implantation, Endosseous / Q000379:methods; D015921:Dental Implants; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention / Q000295:instrumentation; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003826:Denture, Complete, Lower; D006047:Gold Alloys; D006801:Humans; D007575:Jaw, Edentulous / Q000000981:diagnostic imaging; D008334:Mandible / Q000000981:diagnostic imaging / Q000601:surgery; D008875:Middle Aged; D010165:Palladium; D011446:Prospective Studies; D011859:Radiography; D015203:Reproducibility of Results; D012834:Silver
chemical_list: D003722:Dental Alloys; D015921:Dental Implants; D006047:Gold Alloys; D012834:Silver; D010165:Palladium