title: Experimental zirconia abutments for implant-supported single-tooth restorations in esthetically demanding regions: 4-year results of a prospective clinical study.
abstract: OBJECTIVE
  This prospective clinical study evaluated an experimental implant abutment made of densely sintered zirconia with respect to peri-implant hard and soft tissue reaction as well as fracture resistance over time.
  
  
  METHODS
  Twenty-seven consecutively treated patients with 54 single-tooth implants were included. Zirconia abutment ingots were individually shaped and set on the implants with gold screws. All-ceramic (Empress I) crowns were cemented using a composite cement. At the 1- and 4-year examinations, reconstructions were evaluated for technical problems (fracture of abutment or crown, loosening of abutment screw). Modified Plaque and simplified Gingival Indices were recorded at implants and neighboring teeth, and peri-implant bone levels were radiographically determined.
  
  
  RESULTS
  All but 1 of the 27 patients with 53 restorations could be evaluated at 1 year, and 36 restorations in 18 patients were evaluated 4 years after abutment and crown insertion. The median observation period for the reconstructions was 49.2 months. No abutment fractures occurred. Abutment screw loosening was reported for 2 restorations at 8 months and 27 months, respectively. Mean Plaque Index was 0.4 (SD 0.6) at abutments and 0.5 (SD 0.6) at teeth; mean Gingival Index was 0.7 (SD 0.5) at abutments and 0.9 (SD 0.5) at teeth. Mean marginal bone loss measured 1.2 mm (SD 0.5) after 4 years of functional loading.
  
  
  CONCLUSIONS
  Zirconia abutments offered sufficient stability to support implant-supported single-tooth reconstructions in anterior and premolar regions. The soft and hard tissue reaction toward zirconia was favorable.
authors.affiliation: Department of Fixed and Removable Prosthodontics, University of Zürich, Switzerland. glauser@zzmk.unizh.ch
authors.forename: Roland
authors.initials: R
authors.lastname: Glauser
authors.forename: Irena
authors.initials: I
authors.lastname: Sailer
authors.forename: Arnold
authors.initials: A
authors.lastname: Wohlwend
authors.forename: Stephan
authors.initials: S
authors.lastname: Studer
authors.forename: Monica
authors.initials: M
authors.lastname: Schibli
authors.forename: Peter
authors.initials: P
authors.lastname: Schärer
mesh_terms: D000328:Adult; D000368:Aged; D001641:Bicuspid; D003442:Crowns; D000044:Dental Abutments; D019250:Dental Implants, Single-Tooth; D003774:Dental Plaque Index; D017267:Dental Prosthesis Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007180:Incisor; D008297:Male; D016876:Metal Ceramic Alloys; D008875:Middle Aged; D010512:Periodontal Index; D011446:Prospective Studies; D016019:Survival Analysis; D015040:Zirconium
chemical_list: D016876:Metal Ceramic Alloys; D015040:Zirconium; C028541:zirconium oxide