title: Rehabilitation of edentulous mandibles by means of four TiUnite implants after one-stage surgery: a 1-year retrospective study of 75 patients.
abstract: BACKGROUND
  Recently, the present team reported the 1-year data of a one-stage surgery and mainly early loading with five supporting implants in completely edentulous mandibles, indicating more bone loss at the central implant, placed in the midline of the jaw.
  
  
  OBJECTIVE
  The aim of the present retrospective investigation was to evaluate the 1-year results of the same treatment technique with four instead of five supporting implants in completely edentulous mandibles. The outcome was compared with that of a former study (control) on five implants per patient during first year of function.
  
  
  METHODS
  The present study comprised 75 patients with a total of 300 TiUnite implants (Nobel Biocare AB, Göteborg, Sweden) of mainly the Brånemark System >or= Mark III design. The prosthetic procedure started and was completed on an average of 9.1 days (standard deviation [SD] 4.47) and 33.2 days (SD 16.09) after the surgical intervention, respectively. Intraoral radiographs were obtained at prosthesis insertion and at the 1-year follow-up visit. Failure rates of test and control groups were compared by means of the chi-squared test.
  
  
  RESULTS
  All four implants in one patient were found to be mobile at the first annual check-up, resulting in an implant cumulative survival rate (CSR) of 98.5%. The corresponding CSR for the control group was 100% (p > 0.05). The mean marginal bone resorption during the first year of function was 0.3 mm (SD 0.74) as compared with 0.5 (SD 0.56) mm for the control group (p > 0.05).
  
  
  CONCLUSIONS
  The outcome of 300 TiUnite implants placed in 75 patients with edentulous mandibles, of which 268 implants in 67 patients were followed for 1 year, showed an implant CSR of 98.5%. The implant survival was not significantly different from that of the control study result of 100%, in which five instead of four supporting implants were used. The levels of marginal bone were close to identical for the corresponding test and control implants at the 1-year check-up.
authors.affiliation: The Brånemark Clinic, Public Dental Health Service, Göteborg, Sweden. bertil.friberg@vgregion.se
authors.forename: Bertil
authors.initials: B
authors.lastname: Friberg
authors.forename: Torsten
authors.initials: T
authors.lastname: Jemt
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging; D016009:Chi-Square Distribution; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003826:Denture, Complete, Lower; D005260:Female; D006801:Humans; D007575:Jaw, Edentulous / Q000534:rehabilitation*; D015993:Life Tables; D008297:Male; D008334:Mandible / Q000601:surgery; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D013499:Surface Properties; D014025:Titanium
chemical_list: D015921:Dental Implants; C009495:titanium dioxide; D014025:Titanium