title: Microtensile bond strength and impact energy of fracture of CAD-veneered zirconia restorations.
abstract: OBJECTIVE
  With state-of-the-art CAD/CAM technology, the fabrication of large and complex zirconia frameworks is just a click away. On the other hand, veneering of the frameworks is still operator-dependent. The aim of this work was to evaluate CAD veneering of zirconia restorations in terms of zirconia veneer bond strength and impact energy of fracture in a step towards complete automation of the fabrication process.
  
  
  METHODS
  A new CAD/CAM system was used to fabricate a resin replica of the esthetic ceramic required to veneer a zirconia framework. The replica was seated on the zirconia framework and further processed using press-on technology. The bond strength between zirconia and the CAD veneer was evaluated using microtensile bond strength test. The impact energy of fracture of the specimens was also investigated. Manually layered zirconia specimens served as a control (alpha= 0.05).
  
  
  RESULTS
  There was no significant difference in the microtensile bond strength between zirconia and either of the used veneers (39 MPa). Even though the impact energy of fracture of the CAD-veneered and manually layered specimens was almost identical (0.13 J), the former demonstrated a cohesive fracture of the veneer, while the latter failed by delamination of the veneer ceramic.
  
  
  CONCLUSIONS
  CAD veneering is a reliable method for veneering zirconia restorations.
authors.affiliation: Dental Biomaterials Department, Faculty of Dentistry, Alexandria University, Egypt. bluemarline_1@yahoo.com
authors.forename: Moustafa N
authors.initials: MN
authors.lastname: Aboushelib
authors.forename: Marcel
authors.initials: M
authors.lastname: de Kler
authors.forename: Jef M
authors.initials: JM
authors.lastname: van der Zel
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Feilzer
mesh_terms: D017076:Computer-Aided Design; D003442:Crowns; D001840:Dental Bonding; D003764:Dental Materials / Q000737:chemistry*; D003768:Dental Occlusion, Centric; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D003801:Dental Veneers; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D008963:Molar; D013314:Stress, Mechanical; D013499:Surface Properties; D013674:Technology, Dental; D013718:Tensile Strength; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003764:Dental Materials; D015040:Zirconium; C028541:zirconium oxide