title: The implant-abutment interface of alumina and zirconia abutments.
abstract: BACKGROUND
  Although ceramic and titanium abutments are widely used in clinical practice, the mechanical characterization of the implant-abutment interface for ceramic abutments has not been evaluated after the dynamic loading.
  
  
  OBJECTIVE
  The purpose of this study was to assess the implant-abutment interface after the dynamic loading of titanium, alumina, and zirconia abutments.
  
  
  METHODS
  Fifteen aluminum oxide, zirconium oxide, and titanium abutments were manufactured by the Procera System (Nobel Biocare AB, Göteborg, Sweden) and were connected to Ø 3.75 x 13-mm regular platform implants (MK III, Nobel Biocare AB) secured in a 30 degrees inclined plane. A mechanical testing machine applied compressive dynamic loading between 20 and 200 N at 1 Hz on a standard contact area of copings cemented on abutments for 47.250 cycles. The measurements of microgaps at the implant-abutment interface from the labial, palatinal, mesial, and distal surfaces of each specimen were undertaken by scanning electron microscope analyses prior to and after the experiments. The data of the microgaps before and after the dynamic loading were statistically assessed using the Wilcoxon signed rank test and the Kruskal-Wallis variance analysis (alpha = 0.05).
  
  
  RESULTS
  Coping fracture, abutment fracture, or abutment screw loosening or fracture was not detected in any specimen during the entire test period. After the dynamic loading, the titanium abutment control group revealed an increased microgap (3.47 microm) than zirconia (1.45 microm) and alumina (1.82 microm) groups at the palatinal site (p < .05). The mean measurement values at different measurement sites of specimens within and between each abutment group were similar (p > .05).
  
  
  CONCLUSIONS
  Owing to their comparable microgap values at the implant-abutment interface after the dynamic loading, ceramic abutments can withstand functional forces like conventional titanium abutments.
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, Hacettepe University, 06100 Sihhiye, Ankara, Turkey. bulemy@gmail.com
authors.forename: Bulem
authors.initials: B
authors.lastname: Yüzügüllü
authors.forename: Mehmet
authors.initials: M
authors.lastname: Avci
mesh_terms: D000537:Aluminum Oxide; D000044:Dental Abutments; D015921:Dental Implants; D003799:Dental Stress Analysis; D008855:Microscopy, Electron, Scanning; D018709:Statistics, Nonparametric; D013499:Surface Properties; D014025:Titanium; D015040:Zirconium
chemical_list: D015921:Dental Implants; D015040:Zirconium; D014025:Titanium; D000537:Aluminum Oxide; C028541:zirconium oxide