title: Randomized controlled clinical pilot study of all-ceramic single-tooth implant reconstructions: clinical and microbiological outcomes at one year of loading.
abstract: OBJECTIVE
  To test whether or not pink veneering of the submucosal part of zirconia abutments influences clinical, microbiological and histological outcomes of cemented implant-supported single crowns (ISSC).
  
  
  METHODS
  A total of 20 patients with one single-tooth implant in the esthetic zone were included. Implants were randomly restored with either pink-veneered zirconia abutments (test group; n = 10) or non-veneered white zirconia abutments (control group; n = 10) and with adhesively cemented all-ceramic crowns. At the 6-month follow-up, soft tissue biopsies were prepared for histological evaluation and microbiological samples were collected around abutments and the respective contra-lateral teeth (in 10 of 20 patients). One year after the initiation of loading, clinical parameters were assessed. Robust linear mixed model and cumulative linked mixed model analyses were performed to investigate the effect of group and time-point on clinical and biological outcomes.
  
  
  RESULTS
  Clinical evaluations revealed stable peri-implant soft tissues in terms of probing pocket depth, but a high BOP index (87.5% control; 80.0% test). No statistically significant differences were observed between the test and control group for any outcome measure (P > 0.05). No major biological complications occurred during the observation period. Histological samples revealed a remarkable degree of inflammation in both groups without clear differences in qualitative histological features. Microbiological evaluation demonstrated a slightly higher bacterial count at implants compared to natural teeth at one year of loading without marked differences between groups.
  
  
  CONCLUSIONS
  Limited by a small sample size and a relatively short observation period, pink-veneered zirconia abutments exhibited similar clinical, histological and microbiological outcomes as non-veneered zirconia abutments supporting cemented single crowns.
authors.affiliation: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Zürich, Switzerland.
authors.forename: Francine D
authors.initials: FD
authors.lastname: Brandenberg
authors.affiliation: Division of Fixed Prosthodontics and Biomaterials, Clinic of Dental Medicine, University of Geneva, Geneva, Switzerland.
authors.forename: Irena
authors.initials: I
authors.lastname: Sailer
authors.affiliation: Division of Fixed Prosthodontics and Biomaterials, Clinic of Dental Medicine, University of Geneva, Geneva, Switzerland.
authors.forename: Vincent
authors.initials: V
authors.lastname: Fehmer
authors.affiliation: Private practice, Chur, Switzerland.
authors.forename: Dominik L E
authors.initials: DL
authors.lastname: Büchi
authors.affiliation: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Zürich, Switzerland.
authors.forename: Christoph H F
authors.initials: CH
authors.lastname: Hämmerle
authors.affiliation: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Zürich, Switzerland.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Thoma
mesh_terms: D000328:Adult; D000368:Aged; D002516:Ceramics; D003442:Crowns; D019250:Dental Implants, Single-Tooth / Q000382:microbiology*; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003801:Dental Veneers; D004955:Esthetics, Dental; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D055815:Young Adult; D015040:Zirconium
chemical_list: D015040:Zirconium
keywords: ceramic abutments; crowns; dental abutments; dental implants; titanium abutments; zirconia