title: Crestal bone changes around implants with reduced abutment diameter placed non-submerged and at subcrestal positions: a 1-year radiographic evaluation.
abstract: BACKGROUND
  There is limited information about two-part implants placed in subcrestal positions. The aim of this study is to retrospectively evaluate the 1-year outcome of implants placed non-submerged and in a subcrestal position.
  
  
  METHODS
  Records of 50 consecutive partially edentulous patients restored with dental implants were reviewed. For each implant, radiographs from the surgical appointment were compared to those from the 1-year follow-up visit and evaluated regarding: 1) the degree of subcrestal positioning of the implant, 2) changes of marginal hard tissue height over time, and 3) if the marginal hard tissue could be detected on the implant platform at the follow-up visit.
  
  
  RESULTS
  The overall survival rate from baseline to the last recorded follow-up visit was 100%. At the surgery, the implants were placed, on average, 1.37 mm (mesial) and 1.28 mm (distal) subcrestally. The mean marginal loss of hard tissues was 0.11 +/- 0.30 mm. There were no statistical significant differences regarding the loss of marginal hard tissues between mesial and distal surfaces or the maxilla versus the mandible. There was no statistical significant correlation regarding the degree of subcrestal implant position and loss of marginal mineralized hard tissue (r = 0.15; P >0.05). The mineralized hard tissue on the implant shoulder was found in 69% of the implants at the 1-year follow-up visit.
  
  
  CONCLUSIONS
  The present study reported a minimal loss of mineralized hard tissue around dental implants placed non-submerged and at subcrestal positions. In addition, these implants had hard tissue healing that extended onto the implant shoulders on most of the observed implants.
authors.affiliation: Department of Periodontology, College of Dentistry, University of Florida, Gainesville, FL 32608, USA.
authors.forename: Ryan
authors.initials: R
authors.lastname: Donovan
authors.forename: Alan
authors.initials: A
authors.lastname: Fetner
authors.forename: Theofilos
authors.initials: T
authors.lastname: Koutouzis
authors.forename: Tord
authors.initials: T
authors.lastname: Lundgren
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging / Q000209:etiology / Q000517:prevention & control*; D000044:Dental Abutments; D003758:Dental Implantation, Endosseous / Q000009:adverse effects / Q000379:methods*; D015921:Dental Implants / Q000009:adverse effects; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D015921:Dental Implants