title: A prospective multicenter clinical trial of 3i machined-surface implants: results after 6 years of follow-up.
abstract: OBJECTIVE
  In this prospective multicenter clinical study, 1,179 3i standard threaded and self-tapping implants were followed for up to 6 years and monitored according to established success criteria.
  
  
  METHODS
  A total of 493 patients (240 men and 253 women) with a mean age of 45.1 years at implant surgery were enrolled at 6 research centers after being screened for exclusion criteria. Implants were placed according to a 2-stage surgical protocol with a minimum of 4 months of submerged healing in the mandible and 6 months in the maxilla. Restorations included 633 prostheses, the majority of which were fixed partial dentures in the posterior mandible or maxilla or single-tooth replacements in the anterior maxilla.
  
  
  RESULTS
  One hundred four implants (8.8%) did not meet success criteria and were designated as failures, and 222 implants (18.8%) were lost to follow-up. The cumulative success rate according to life table methods was 91.1% at 6 years.
  
  
  CONCLUSIONS
  Sixty percent of the failed implants were short (< or = 10 mm long), and their cumulative success rate as a group at 6 years was 89.0%, compared to 93.1% for longer implants (P < .05). Thirty-three percent of all failures were implants placed in the posterior maxilla, for a 5-year cumulative success rate of 87.4%.
  
  
  CONCLUSIONS
  It appears that limited bone dimensions and poor-quality bone have an impact on the performance of these machined-surface implants.
authors.affiliation: Department of Prosthodontics, School of Dental Medicine, Bavarian Julius-Maximilians-University of Würzburg, Germany. dietmar.weng@mail.uni-wuerzburg.de
authors.forename: Dietmar
authors.initials: D
authors.lastname: Weng
authors.forename: Zhimon
authors.initials: Z
authors.lastname: Jacobson
authors.forename: Dennis
authors.initials: D
authors.lastname: Tarnow
authors.forename: Markus B
authors.initials: MB
authors.lastname: Hürzeler
authors.forename: Ove
authors.initials: O
authors.lastname: Faehn
authors.forename: Farshid
authors.initials: F
authors.lastname: Sanavi
authors.forename: Pål
authors.initials: P
authors.lastname: Barkvoll
authors.forename: Renée M
authors.initials: RM
authors.lastname: Stach
mesh_terms: D015519:Bone Density; D003758:Dental Implantation, Endosseous / Q000379:methods; D015921:Dental Implants; D019250:Dental Implants, Single-Tooth; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003830:Denture, Partial, Fixed; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015993:Life Tables; D008297:Male; D008334:Mandible / Q000601:surgery; D008437:Maxilla / Q000601:surgery; D008875:Middle Aged; D010512:Periodontal Index; D011446:Prospective Studies; D013499:Surface Properties; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants