title: Randomized controlled clinical trial of customized zirconia and titanium implant abutments for canine and posterior single-tooth implant reconstructions: preliminary results at 1 year of function.
abstract: OBJECTIVE
  The aim of this study was to test whether or not customized zirconia abutments exhibit the same survival rates in canine and posterior regions as titanium abutments, and to compare the esthetic result of the two abutment types.
  
  
  METHODS
  Twenty-two patients with 40 implants in posterior regions were included and the implant sites were randomly assigned to 20 customized zirconia and 20 customized titanium abutments. All-ceramic (AC) and metal-ceramic (MC) crowns were fabricated. In all except two cases, the crowns were cemented on the abutments using resin or glass-ionomer cements. Two zirconia reconstructions were screw retained. At baseline, 6 and 12 months, the reconstructions were examined for technical and biological problems. Probing pocket depth (PPD), plaque (Pl) and bleeding on probing (BOP) were assessed and compared with natural control teeth. Furthermore, the difference of color (DeltaE) of the peri-implant mucosa and the gingiva of control teeth was evaluated by means of a spectrophotometer (Spectroshade). The data were analyzed with Student's unpaired t-test, ANOVA and regression analyses.
  
  
  RESULTS
  Twenty patients with 19 zirconia and 12 titanium abutments were examined at a mean follow-up of 12.6+/-2.7 months. The survival rate for reconstructions and abutments was 100%. No technical or biological problems were found at the test and control sites. Two chippings (16.7%) occurred at crowns supported by titanium abutments. No difference was found regarding PPD (meanPPD(ZrO2) 3.4+/-0.7 mm, mPPD(Ti) 3.3+/-0.6 mm), Pl (mPl(ZrO2) 0.2+/-0.3, mPl(Ti) 0.1+/-1.8) and BOP (mBOP(ZrO2) 60+/-30%, mBOP(Ti) 30+/-40%) between the two groups. Both crowns on zirconia and titanium abutments induced a similar amount of discoloration of the soft tissue compared with the gingiva at natural teeth (DeltaE(ZrO2) 8.1+/-3.9, DeltaE(Ti) 7.8+/-4.3).
  
  
  CONCLUSIONS
  At 1 year, zirconia abutments exhibited the same survival and a similar esthetic outcome as titanium abutments.
authors.affiliation: Department of Fixed and Removable Prosthodontics and Dental Material Science, School of Dental Medicine, University of Zurich, Plattenstrasse 118032 ZurichSwitzerland. irena.sailer@zzmk.uzh.ch
authors.forename: Irena
authors.initials: I
authors.lastname: Sailer
authors.forename: Anja
authors.initials: A
authors.lastname: Zembic
authors.forename: Ronald Ernst
authors.initials: RE
authors.lastname: Jung
authors.forename: David
authors.initials: D
authors.lastname: Siegenthaler
authors.forename: Claudia
authors.initials: C
authors.lastname: Holderegger
authors.forename: Christoph Hans Franz
authors.initials: CH
authors.lastname: Hämmerle
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D003442:Crowns; D003481:Cuspid; D000044:Dental Abutments; D019250:Dental Implants, Single-Tooth; D003776:Dental Porcelain; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000379:methods*; D004955:Esthetics, Dental; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D008963:Molar; D018709:Statistics, Nonparametric; D014025:Titanium; D015040:Zirconium
chemical_list: D003776:Dental Porcelain; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide