title: A comparison between 4 and 6 implants in the maxillary posterior region to support an overdenture; 1-year results from a randomized controlled trial.
abstract: OBJECTIVE
  To compare the treatment outcome of 4 vs. 6 bar-connected implants in the posterior region of the maxilla to support an overdenture during a 1-year follow-up period.
  
  
  METHODS
  Sixty-six edentulous patients with an insufficient amount of bone volume in the maxilla to place implants were asked to participate in this study. Randomization assigned patients to either 4 or 6 implants. In all patients, a maxillary sinus floor elevation procedure with bone from the iliac crest was performed, and after a 3-month healing period, 4 or 6 dental implants were inserted in the maxillary posterior region in a one-stage procedure. After 3 months of osseointegration, a bar-supported overdenture was constructed. Implant survival, overdenture survival, clinical scores, peri-implant bone height changes and patients' satisfaction were assessed. Study analysis was performed according a non-inferiority design.
  
  
  RESULTS
  All patients completed the one-year follow-up. After a functional period of 1-year, implant survival was 100% in the 4 implants group and 99.5% in the 6 implants group. Overdenture survival was 100% in both groups. Mean clinical scores were very low and did not significantly differ between groups. Mean marginal bone resorption was 0.35 ± 0.31 mm and 0.46 ± 0.34 mm in the 4 and 6 implants group, respectively. Patients' satisfaction improved significantly in both groups, but did not differ between groups.
  
  
  CONCLUSIONS
  A bar-supported overdenture on 4 implants in the posterior maxillary region is not inferior to an overdenture supported by 6 bar-connected dental implants.
authors: Department of Fixed and Removable Prosthodontics, Dental School, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors: Wim
authors: W
authors: Slot
authors: Gerry M
authors: GM
authors: Raghoebar
authors: Arjan
authors: A
authors: Vissink
authors: Henny J A
authors: HJ
authors: Meijer
mesh_terms: D000328:Adult; D000368:Aged; D015921:Dental Implants; D017268:Dental Prosthesis Retention; D019094:Dental Prosthesis, Implant-Supported; D003828:Denture, Overlay; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007575:Jaw, Edentulous / Q000601:surgery*; D008297:Male; D008437:Maxilla / Q000601:surgery*; D008875:Middle Aged; D017060:Patient Satisfaction; D059546:Sinus Floor Augmentation; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants
keywords: dental implants; edentulous; healthy ageing; maxilla; overdenture