title: On the interfacial fracture resistance of resin-bonded zirconia and glass-infiltrated graded zirconia.
abstract: OBJECTIVE
  A major limiting factor for the widespread use of zirconia in prosthetic dentistry is its poor resin-cement bonding capabilities. We show that this deficiency can be overcome by infiltrating the zirconia cementation surface with glass. Current methods for assessing the fracture resistance of resin-ceramic bonds are marred by uneven stress distribution at the interface, which may result in erroneous interfacial fracture resistance values. We have applied a wedge-loaded double-cantilever-beam testing approach to accurately measure the interfacial fracture resistance of adhesively bonded zirconia-based restorative materials.
  
  
  METHODS
  The interfacial fracture energy GC was determined for adhesively bonded zirconia, graded zirconia and feldspathic ceramic bars. The bonding surfaces were subjected to sandblasting or acid etching treatments. Baseline GC was measured for bonded specimens subjected to 7 days hydration at 37°C. Long-term GC was determined for specimens exposed to 20,000 thermal cycles between 5 and 55°C followed by 2-month aging at 37°C in water. The test data were interpreted with the aid of a 2D finite element fracture analysis.
  
  
  RESULTS
  The baseline and long-term GC for graded zirconia was 2-3 and 8 times greater than that for zirconia, respectively. More significantly, both the baseline and long-term GC of graded zirconia were similar to those for feldspathic ceramic.
  
  
  CONCLUSIONS
  The interfacial fracture energy of feldspathic ceramic and graded zirconia was controlled by the fracture energy of the resin cement while that of zirconia by the interface. GC for the graded zirconia was as large as for feldspathic ceramic, making it an attractive material for use in dentistry.
authors.affiliation: Tel Aviv University, School of Mechanical Engineering, Faculty of Engineering, Tel Aviv, Israel.
authors.forename: Herzl
authors.initials: H
authors.lastname: Chai
authors.affiliation: New York University College of Dentistry, Department of Biomaterials and Biomimetics, 433 First Avenue, Room 810, New York, NY 10010, USA; Federal University of Pelotas, Graduate Program in Dentistry, Pelotas, Brazil.
authors.forename: Marina
authors.initials: M
authors.lastname: Kaizer
authors.affiliation: New York University College of Dentistry, Department of Biomaterials and Biomimetics, 433 First Avenue, Room 810, New York, NY 10010, USA.
authors.forename: Asima
authors.initials: A
authors.lastname: Chughtai
authors.affiliation: New York University College of Dentistry, Department of Biomaterials and Biomimetics, 433 First Avenue, Room 810, New York, NY 10010, USA; School of Metallurgy and Environment, Central South University, Changsha, Hunan 410083, PR China.
authors.forename: Hui
authors.initials: H
authors.lastname: Tong
authors.affiliation: New York University College of Dentistry, Department of Biomaterials and Biomimetics, 433 First Avenue, Room 810, New York, NY 10010, USA; Department of Biomaterial and Oral Biology, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: Carina
authors.initials: C
authors.lastname: Tanaka
authors.affiliation: New York University College of Dentistry, Department of Biomaterials and Biomimetics, 433 First Avenue, Room 810, New York, NY 10010, USA. Electronic address: yz21@nyu.edu.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D001840:Dental Bonding; D003776:Dental Porcelain; D003799:Dental Stress Analysis; D008422:Materials Testing; D019279:Resin Cements; D013314:Stress, Mechanical; D013499:Surface Properties; D015040:Zirconium
chemical_list: D019279:Resin Cements; D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide
keywords: Cement bond; Feldspathic ceramic; Glass-infiltrated graded zirconia; Interfacial fracture energy; Wedge-loaded double-cantilever-beam; Zirconia