title: Removable implant-prosthodontic rehabilitation of the edentulous mandible: five-year results of different prosthetic anchorage concepts.
abstract: OBJECTIVE
  The present study evaluated implant and peri-implant outcomes as well as prosthodontic maintenance efforts for implant/bar-supported mandibular prostheses with different prosthesis anchorage systems.
  
  
  METHODS
  Seventy-six patients who received two or four interforaminal implants were assigned to one of three different bar designs and subsequently to different prosthesis supporting systems. Forty-nine patients received implants and a mucosa-supported implant-retained overdenture (OD) with an ovoid bar (two implants; design 1) or multiple ovoid bars (four implants; design 2). Twenty-seven patients received four implants and a rigid implant-supported prosthesis (ISP) with a milled bar (design 3). Implant survival, peri-implant parameters (marginal bone resorption, pocket depth, and plaque, bleeding, gingival, and calculus indices), and postinsertion prosthodontic maintenance were followed over a 5-year period and compared among the different retention modalities. At the most recent follow-up examination, subjective patient satisfaction was additionally evaluated using a simplified scoring system (ranging from 1 = not satisfactory to 5 = excellent).
  
  
  RESULTS
  Implant survival rates (100%) and all peri-implant parameters evaluated showed no differences among the three designs used for implant prosthesis anchorage. Prosthodontic maintenance did not differ between the different ODs (OD design 1: average of 1.04 maintenance visits/year/patient; OD design 2: 1.2 maintenance visits/year/patient), but it was significantly lower for the dentures that were rigidly stabilized with milled bars (ISP: 0.37 maintenance visits/year/patient). A high subjective satisfaction rate (range: 4.5 to 5.0) was registered at the final examination, without any differences among the designs used.
  
  
  CONCLUSIONS
  Rigid anchorage with milled bars on four-implant prostheses combined with a metal-reinforced framework showed a lower extent of prosthodontic maintenance issues than round bars on two- or four-implant overdentures with resilient denture stabilization. Nevertheless, implants and peri-implant structures were not negatively affected by either resilient or rigid anchorage mechanisms.
authors.affiliation: Department of Prosthdontics, University of Vienna, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Weinländer
authors.forename: Eva
authors.initials: E
authors.lastname: Piehslinger
authors.forename: Gerald
authors.initials: G
authors.lastname: Krennmair
mesh_terms: D003758:Dental Implantation, Endosseous; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention / Q000295:instrumentation*; D019094:Dental Prosthesis, Implant-Supported; D003823:Denture Rebasing; D003780:Denture Repair; D003828:Denture, Overlay; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007575:Jaw, Edentulous / Q000534:rehabilitation* / Q000601:surgery; D008297:Male; D008334:Mandible / Q000601:surgery; D008875:Middle Aged; D017060:Patient Satisfaction