title: A clinical study of edentulous patients rehabilitated according to the "all on four" immediate function protocol.
abstract: OBJECTIVE
  The aim of this study was to compare definitive acrylic resin prostheses with or without a cast metal framework that were immediately loaded and supported by axial and tilted implants in completely edentulous patients after 3 years of function.
  
  
  METHODS
  Patients who were completely or partially edentulous in one or both arches with severe atrophy of the posterior regions were selected for this study. All patients immediately received prosthetic rehabilitations, each supported by four implants (two axial and two tilted). The patients were randomized to receive a definitive prosthesis with a cast metal framework or one made of acrylic resin only. Follow-up visits were performed up to 36 months after implant insertion and included radiographic assessments of bone levels around the implants.
  
  
  RESULTS
  Thirty-six patients participated, and 44 complete-arch immediately loaded prostheses (24 maxillary and 20 mandibular), each supported by four implants (in total 176 implants), were placed. In all, 21 screw-retained full-arch acrylic resin prostheses and 23 cast-metal-framework prostheses were delivered to the patients. The 3-year overall implant survival rate was 100% for axially positioned implants and 96.59% for tilted implants. Implant survival rates were 98.96% in the maxilla and 97.5% in the mandible. None of the 44 fixed prostheses were lost during the observation period, representing a prosthetic survival rate of 100%. No statistically significant differences were seen in crestal bone loss between tilted and axial implants at 12, 24, and 36 months in either arch.
  
  
  CONCLUSIONS
  The same clinical outcome was seen for patients treated with the so-called All on Four protocol, regardless of whether the acrylic resin restorations were reinforced with metal.
authors.affiliation: Department of Dentistry, Vita Salute University, San Raffaele Hospital, Milan, Italy. robcresp@libero.it
authors.forename: Roberto
authors.initials: R
authors.lastname: Crespi
authors.forename: Raffaele
authors.initials: R
authors.lastname: Vinci
authors.forename: Paolo
authors.initials: P
authors.lastname: Capparé
authors.forename: George E
authors.initials: GE
authors.lastname: Romanos
authors.forename: Enrico
authors.initials: E
authors.lastname: Gherlone
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging; D000539:Alveolar Process / Q000000981:diagnostic imaging; D003722:Dental Alloys / Q000737:chemistry; D059605:Dental Implant-Abutment Design; D003764:Dental Materials / Q000737:chemistry; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003779:Denture Design; D003781:Denture Retention / Q000295:instrumentation; D003824:Denture, Complete; D003825:Denture, Complete, Immediate; D003828:Denture, Overlay; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D057893:Immediate Dental Implant Loading / Q000379:methods*; D007575:Jaw, Edentulous / Q000534:rehabilitation* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011859:Radiography; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D000180:Acrylic Resins; D003722:Dental Alloys; D003764:Dental Materials