title: Randomized multicenter comparison of 2 IMZ and 4 TPS screw implants supporting bar-retained overdentures in 425 edentulous mandibles.
abstract: OBJECTIVE
  Two treatment concepts for implant-supported bar retention of mandibular overdentures-2 intramobile cylinder (IMZ) implants and a Dolder bar and 4 titanium plasma-sprayed (TPS) screw implants and an angulated bar-were compared in a randomized controlled clinical trial with respect to postprosthetic efficacy and safety.
  
  
  METHODS
  Four hundred twenty-five patients with edentulous mandibles were enrolled; 212 were randomized to TPS implants (control group) and 213 to IMZ implants (test group). Endpoints were occurrences of postprosthetic integration deficiency (ID), functional deficiency (FD), and complications. The trial was sized to detect a 10% difference in 5-year ID-free postprosthetic system lifetime with a power of 80%.
  
  
  RESULTS
  With 340 protocol-completed cases, the trial achieved its predetermined power. The 2 systems did not show statistically significant differences in occurrences of postprosthetic ID and FD; 5-year occurrence-free postprosthetic system lifetime probabilities were estimated as 42.5% with IMZ and 42.8% with TPS, for ID; and as 82.6% with IMZ and 87.2% with TPS, for FD. However, at 3 to 6 months after surgery, mean Periotest values were significantly higher (P = .0001 without adjustment) with IMZ implants (5.6, SD 4.2) than with TPS implants (0.8, SD 4.3). TPS implants showed a higher incidence of inflammation and recession, while IMZ implants had a higher incidence of implant fracture after functional loading.
  
  
  CONCLUSIONS
  The system-wise approach overcomes potential bias with implant-wise analyses. A combination of radiographic and clinical criteria distinguishes between desirable integration and functional anchorage. The in situ survival rates at 5 years in this study (95% for IMZ, 92% for TPS) match rates reported in the literature.
  
  
  CONCLUSIONS
  This study demonstrated equivalent efficacy of 2 IMZ cylinders and 4 TPS screws in implant-supported, bar-retained mandibular overdentures and indicated a higher rate of complications with the TPS screw implants.
authors.affiliation: Department of Statistics in Medicine, Heinrich Heine University, Duesseldorf, Germany. ismmau@uni-duesseldorf.de
authors.forename: Jochen
authors.initials: J
authors.lastname: Mau
authors.forename: Alexandra
authors.initials: A
authors.lastname: Behneke
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Behneke
authors.forename: Claus Udo
authors.initials: CU
authors.lastname: Fritzemeier
authors.forename: German
authors.initials: G
authors.lastname: Gomez-Roman
authors.forename: Bernd
authors.initials: B
authors.lastname: d'Hoedt
authors.forename: Hubertus
authors.initials: H
authors.lastname: Spiekermann
authors.forename: Volker
authors.initials: V
authors.lastname: Strunz
authors.forename: Mei
authors.initials: M
authors.lastname: Yong
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003779:Denture Design; D003781:Denture Retention; D003828:Denture, Overlay; D005260:Female; D005500:Follow-Up Studies; D005889:Gingival Recession / Q000145:classification; D006801:Humans; D007575:Jaw, Edentulous / Q000601:surgery*; D008297:Male; D008334:Mandible / Q000601:surgery*; D008875:Middle Aged; D016348:Osseointegration; D010518:Periodontitis / Q000145:classification; D016019:Survival Analysis; D014025:Titanium
chemical_list: D015921:Dental Implants; D014025:Titanium