title: Effect of roughened micro-threaded implant neck  and platform switching on marginal bone loss:  a multicenter retrospective study with 6-year follow-up.
abstract: OBJECTIVE
  The aim of this retrospective study was to evaluate medium-term marginal peri-implant bone loss following placement of root-form implants featuring a micro-threaded rough-surfaced neck and a platform-switched implant-abutment connection.
  
  
  METHODS
  Records were identified of patients treated with such implants over a 3-year period at three Italian dental centers. Patient radiographs were digitized and subjected to computerized analysis of peri-implant bone resorption.
  
  
  RESULTS
  Records of 112 patients who received 257 implants were analyzed. Although implant diameters and lengths varied, all had a 0.3-mm platform-switching width and a 2.5-mm high micro-threaded neck. All patients healed uneventfully, and no peri-implant infection, implant mobility, or radiolucency around the implant were detected at any follow-up control. At the 72-month control (average 71 ± 5 months) all implants were successful according to Albrektsson and Zarb's criteria. At implant level, average peri-implant bone resorption was 0.18 ± 0.12 mm at 6 months, 0.22 ± 0.15 mm at 12 months, 0.23 ± 0.16 mm at 24 months, 0.25 ± 0.17 mm at 36 months, 0.26 ± 0.15 mm at 48 months, and stable at subsequent controls, regardless of the implant diameter and length. At patient level, a similar trend was observed, with crestal bone loss stabilizing from 48 months onward.
  
  
  CONCLUSIONS
  The surface, geometry, and platform-switching features of the implant under investigation allowed effective bone preservation on a medium-term basis.
authors.forename: Danilo Alessio
authors.initials: DA
authors.lastname: Di Stefano
authors.forename: Edoardo
authors.initials: E
authors.lastname: Giacometti
authors.forename: Gian Battista
authors.initials: GB
authors.lastname: Greco
authors.forename: Giorgio
authors.initials: G
authors.lastname: Gastaldi
authors.forename: Enrico
authors.initials: E
authors.lastname: Gherlone
mesh_terms: D000368:Aged; D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging*; D059605:Dental Implant-Abutment Design; D015921:Dental Implants; D017267:Dental Prosthesis Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013499:Surface Properties; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants