title: A systematic review of implant-supported maxillary overdentures after a mean observation period of at least 1 year.
abstract: OBJECTIVE
  The aim of the present systematic review of implant-supported maxillary overdentures was to assess the survival of implants, survival of maxillary overdentures and the condition of surrounding hard and soft tissues after a mean observation period of at least 1 year.
  
  
  METHODS
  MEDLINE (1950-August 2009), EMBASE (1966-August 2009) and CENTRAL (1800-August 2009) were searched to identify eligible studies. Two reviewers independently assessed the articles.
  
  
  RESULTS
  Out of 147 primarily selected articles, 31 studies fulfilled the inclusion criteria. A meta-analysis showed an implant survival rate (SR) of 98.2% per year in case of six implants and a bar anchorage. In case of four implants and a bar anchorage, the implant SR was 96.3% per person. In case of four implants and a ball anchorage, the implant SR was 95.2% per year.
  
  
  CONCLUSIONS
  In all three treatment options, the SR of the implants is more than 95%. The studies included reveal that a maxillary overdenture supported by six dental implants, which are connected with a bar, is the most successful treatment regarding survival of both the implants and overdenture. Second in line is the treatment option with four implants and a bar. The treatment option with four or less implants and a ball attachment system is the least successful.
authors.affiliation: Department of Prosthetic Dentistry, Dental School, University Medical Center Groningen, Groningen, The Netherlands. j.w.a.slot@med.umcg.nl
authors.forename: Wim
authors.initials: W
authors.lastname: Slot
authors.forename: Gerry M
authors.initials: GM
authors.lastname: Raghoebar
authors.forename: Arjan
authors.initials: A
authors.lastname: Vissink
authors.forename: James J
authors.initials: JJ
authors.lastname: Huddleston Slater
authors.forename: Henny J A
authors.initials: HJ
authors.lastname: Meijer
mesh_terms: D015921:Dental Implants; D019094:Dental Prosthesis, Implant-Supported; D003779:Denture Design; D003781:Denture Retention; D003827:Denture, Complete, Upper; D003828:Denture, Overlay; D005500:Follow-Up Studies; D006801:Humans; D008437:Maxilla / Q000601:surgery*; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants