title: Feasibility and influence of the microgap of two implants placed in a non-submerged procedure: a five-year follow-up clinical trial.
abstract: BACKGROUND
  The aim of this study was to evaluate the feasibility of using a two-piece implant system in a non-submerged procedure and to study the impact of the microgap between the implant and abutment.
  
  
  METHODS
  Sixty edentulous patients (Cawood Class V-VI) participated in this study. After randomization, 20 patients received two two-piece implants placed in a non-submerged procedure, 20 patients received two two-piece implants placed in the traditional submerged procedure, and 20 patients were treated with two one-piece dental implants placed in the traditional non-submerged procedure. The implants were placed in the mandible for overdenture treatment. A standardized clinical evaluation was performed and radiographs were taken immediately after denture insertion and yearly up to 5 years. Peri-implant samples were collected 12, 36, and 60 months after loading with sterile paper points and analyzed for the presence of putative periodontal pathogens using culture techniques.
  
  
  RESULTS
  One two-piece implant of the non-submerged group and one two-piece implant of the submerged group were lost after 6 and 12 months, respectively. After 5 years of functioning, no significant clinical, radiological, or microbiological differences were found between the three groups. No association was found between the level of the microgap and the amount of bone loss.
  
  
  CONCLUSIONS
  The results of this study indicate that dental implants designed for a submerged implantation procedure can also be used in a non-submerged procedure and may be as predictable as when used in a submerged procedure or as one-piece implants. The microgap at the crestal level in two-piece implants does not appear to have an adverse effect on the amount of peri-implant bone loss.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Medical Center Leeuwarden, Leeuwarden, The Netherlands. keesheijdenrijk@planet.nl
authors.forename: Kees
authors.initials: K
authors.lastname: Heijdenrijk
authors.forename: Gerry M
authors.initials: GM
authors.lastname: Raghoebar
authors.forename: Henny J A
authors.initials: HJ
authors.lastname: Meijer
authors.forename: Boudewijn
authors.initials: B
authors.lastname: Stegenga
authors.forename: Wil A
authors.initials: WA
authors.lastname: van der Reijden
mesh_terms: D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging* / Q000382:microbiology; D000044:Dental Abutments / Q000382:microbiology; D003758:Dental Implantation, Endosseous / Q000379:methods* / Q000382:microbiology; D015921:Dental Implants / Q000382:microbiology; D017267:Dental Prosthesis Design / Q000009:adverse effects*; D019094:Dental Prosthesis, Implant-Supported / Q000379:methods; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008297:Male; D008336:Mandibular Diseases / Q000000981:diagnostic imaging* / Q000382:microbiology; D008875:Middle Aged; D011859:Radiography
chemical_list: D015921:Dental Implants