title: The all-on-four treatment concept: a systematic review.
abstract: OBJECTIVE
  The study aims to evaluate the all-on-four treatment concept with regard to survival rates (SRs) of oral implants, applied fixed dental prostheses (FDPs) and temporal changes in proximal bone levels.
  
  
  METHODS
  A systematic review of publications in English and German was performed using the electronic bibliographic database MEDLINE, the Cochrane Library, and Google. Hand searches were conducted of the bibliographies of related journals and systematic reviews. The authors performed evaluations of articles independently, as well as data extraction and quality assessment. Data were submitted the weighted least-squared analysis.
  
  
  RESULTS
  Thirteen (487 initially identified) papers met inclusion criteria. A number of 4,804 implants were initially placed, of which 74 failed, with a majority of failures (74%) within the first 12 months. A total of 1,201 prostheses were incorporated within 48 hours after the surgery. The major prosthetic complication was the fracture of the all-acrylic FDP. The mean cumulative SR/SR ± (standard deviation) (36 months) of implants and prostheses were 99.0 ± 1.0% and 99.9 ± 0.3%, respectively. The averaged bone loss was 1.3 ± 0.4 mm (36 months). No statistically significant differences were found in outcome measures, when comparing maxillary versus mandibular arches and axially versus tilted placed implants.
  
  
  CONCLUSIONS
  The available data provide promising short-term results for the all-on-four treatment approach; however, current evidence is limited by the quality of available studies and the paucity of data on long-term clinical outcomes of 5 years or greater. In terms of an evidence-based dentistry, the authors recommend further studies designed as randomized controlled clinical trials and reported according to the CONSORT statement.
authors.affiliation: Department of Prosthodontics, School of Dentistry, University Hospital, Freiburg, Germany; Department of Periodontics, School of Dentistry, University of Maryland Baltimore, Baltimore, MD, USA.
authors.forename: Sebastian B M
authors.initials: SB
authors.lastname: Patzelt
authors.forename: Oded
authors.initials: O
authors.lastname: Bahat
authors.forename: Mark A
authors.initials: MA
authors.lastname: Reynolds
authors.forename: Joerg R
authors.initials: JR
authors.lastname: Strub
mesh_terms: D016301:Alveolar Bone Loss / Q000209:etiology; D015921:Dental Implants; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003779:Denture Design; D006801:Humans; D008334:Mandible / Q000601:surgery; D008437:Maxilla / Q000601:surgery; D016019:Survival Analysis
chemical_list: D015921:Dental Implants
keywords: all on four; dental implants; systematic review; treatment concept