title: In vitro failure and fracture resistance of veneered and full-contour zirconia restorations.
abstract: OBJECTIVE
  This study evaluated the failure and fracture resistance of zirconia-based fixed partial dentures (FPDs) under the influence of different surface treatments and adjustment procedures.
  
  
  METHODS
  Seven groups (n=8/group) of three-unit zirconia-based FPDs were fabricated in anatomic design (AD) or anatomically reduced design (ARD) and surfaces were prepared according to clinical relevance: #1: AD - sintered; #2: AD - sintered - glazed; #3: AD - sintered - sandblasted - glazed; #4: AD - sintered - polished - grinded (contact points adjusted); #5: AD - sintered - polished - grinded - repolished; #6: ARD - sintered - veneered; #7: control: analogous to #3 but without thermal cycling (TC) and mechanical loading (ML). FPDs were adhesively bonded to polymethylmethacrylate abutment teeth. TCML (TC: 6000 × 5°/55°; ML: 1.2 × 10(6)× 50 N, 1.6 Hz) was conducted in a chewing simulator with steatite spheres as antagonists. Failures were monitored and fracture resistance was determined after ageing. Data were analysed statistically with Mann-Whitney U-test (Kolmogorov-Smirnov-test; α=0.05). FPDs were subjected to scanning electron microscopy for fractographic failure analysis.
  
  
  RESULTS
  None of the FPDs failed during TCML, but showed wear at contact points. Median fracture force ranged between 1173.5 N (#4) and 1316.0 N (#3) without significant (p=0.910) differences between the groups or in comparison to the control (p>0.462).
  
  
  CONCLUSIONS
  Zirconia restorations showed high resistance to failures and fracture under different surface treatment variations. Full-contour polished or glazed zirconia FPDs might be an alternative to common veneered restorations.
authors: Department of Prosthetic Dentistry, University Medical Center Regensburg, 93042 Regensburg, Germany. verena.preis@ukr.de
authors: Verena
authors: V
authors: Preis
authors: Michael
authors: M
authors: Behr
authors: Sebastian
authors: S
authors: Hahnel
authors: Gerhard
authors: G
authors: Handel
authors: Martin
authors: M
authors: Rosentritt
mesh_terms: D000044:Dental Abutments; D003776:Dental Porcelain; D019232:Dental Restoration Failure; D019554:Dental Restoration Wear; D003799:Dental Stress Analysis; D003801:Dental Veneers; D003830:Denture, Partial, Fixed; D018709:Statistics, Nonparametric; D013499:Surface Properties; D015040:Zirconium
chemical_list: D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide