title: Immediate positioning of definitive abutments versus repeated abutment replacements in immediately loaded implants: effects on bone healing at the 1-year follow-up of a multicentre randomised controlled trial.
abstract: OBJECTIVE
  To compare bone resorption around implants immediately loaded and restored using definitive abutments versus provisional abutments later replaced by custom-made abutments up to 12 months after implant placement.
  
  
  METHODS
  28 patients with partial edentulism were selected for a two-implant supported immediate restoration and randomised to provisional abutment (PA) and definitive abutment (DA) groups (14 patients for each group). In the PA group, implants were immediately restored using a platform-switched provisional titanium abutment. In the DA group, definitive platform-switched titanium abutments were tightened. In both groups, a provisional restoration was adapted, avoiding occlusal contacts. All implants were definitively restored after 3 months. In the PA group, patients underwent the standard prosthetic protocol: the abutments were removed and impressions were made directly on the implant platform. In the DA group, patients underwent the 'one abutment at one time' protocol: impressions were made of the abutments using a retraction cord. Peri-implant marginal bone levels were assessed immediately after surgery, and at 6- and 12-month follow-up examinations.
  
  
  RESULTS
  At the 12-month follow-up no implant failed. In the PA group, peri-implant bone resorption was 0.359 mm after 6 months and 0.435 mm after 12 months. In the DA group, peri-implant bone resorption was 0.065 mm after 6 months and 0.094 mm after 12 months. There were statistically significant differences between the two groups for peri-implant bone level changes at the 6-month (P < 0.001) and the 12-month (P < 0.001) follow-up: 0.294 mm (CI 95% 0.276; 0.312) and 0.341 mm (CI 95% 0.322; 0.36), respectively.
  
  
  CONCLUSIONS
  Within the limits of this study, it can be suggested that the non-removal of abutments placed at the time of surgery results in a statistically significant reduction of the crestal bone resorption around the immediately restored implants in cases of partial edentulism, however a difference of 0.3 mm may not have a clinical impact.
authors.affiliation: Department of Integrated Activities of Specialised Head-Neck Surgery, University of Modena and Reggio, Emilia, Italy. tommaso.grandi@unimore.it
authors.forename: Tommaso
authors.initials: T
authors.lastname: Grandi
authors.forename: Paolo
authors.initials: P
authors.lastname: Guazzi
authors.forename: Rawad
authors.initials: R
authors.lastname: Samarani
authors.forename: Giovanna
authors.initials: G
authors.lastname: Garuti
mesh_terms: D000328:Adult; D016301:Alveolar Bone Loss / Q000145:classification* / Q000000981:diagnostic imaging; D003442:Crowns; D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D015921:Dental Implants; D003761:Dental Impression Technique; D019094:Dental Prosthesis, Implant-Supported; D003794:Dental Restoration, Temporary; D005260:Female; D005500:Follow-Up Studies; D060745:Gingival Retraction Techniques / Q000295:instrumentation; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D057893:Immediate Dental Implant Loading; D007576:Jaw, Edentulous, Partially / Q000534:rehabilitation / Q000601:surgery; D008297:Male; D008875:Middle Aged; D016300:Radiography, Bitewing; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants