title: Fracture performance of computer-aided manufactured zirconia and alloy crowns.
abstract: OBJECTIVE
  To compare the fracture resistance and fracture performance of CAD/CAM zirconia and alloy crowns.
  
  
  METHODS
  One electrophoretic deposition alumina ceramic (Wolceram, Wolceram) and 4 zirconia-based systems (ce.novation, ce.novation; Cercon, DeguDent; Digizon, Amann Girrbach; and Lava, 3M ESPE) were investigated. A porcelain-fused-to-metal method (Academy, Bego Medical) was used in either conventional casting technique or laser sintering. Sixteen crowns of each material were fabricated and veneered with glass-ceramic as recommended by the manufacturers. Crown and root dimensions were measured, and 8 crowns of each system were adhesively bonded or conventionally cemented. After the crowns were artificially aged in a simulated oral environment (1,200,000 mechanical loads with 50 N; 3,000 thermal cycles with distilled water between 5 degrees C and 55 degrees C; 2 minutes per cycle), fracture resistance and fracture patterns were determined and defect sizes investigated.
  
  
  RESULTS
  The fracture force varied between 1,111 N and 2,038 N for conventional cementation and between 1,181 N and 2,295 N for adhesive bonding. No significant differences were found between adhesive and conventional cementations. Fracture patterns presented mostly as a chipping of the veneering, in single cases as a fracture of the core, and in 1 case as a fracture of the tooth.
  
  
  CONCLUSIONS
  Crown material and cementation do not have any significant influence on the fracture force and fracture performance of all-ceramic and metal-based crowns. Therefore, it may be concluded that adhesive bonding is not necessary for the application of high-strength ceramics.
authors.affiliation: Department of Prosthetic Dentistry, University Medical Center Regensburg, Regensburg, Germany. martin.rosentritt@klinik.uni-r.de
authors.forename: Martin
authors.initials: M
authors.lastname: Rosentritt
authors.forename: Michael
authors.initials: M
authors.lastname: Behr
authors.forename: Christian
authors.initials: C
authors.lastname: Thaller
authors.forename: Heike
authors.initials: H
authors.lastname: Rudolph
authors.forename: Albert
authors.initials: A
authors.lastname: Feilzer
mesh_terms: D000537:Aluminum Oxide; D002484:Cementation / Q000379:methods; D017076:Computer-Aided Design; D003442:Crowns; D003735:Dental Casting Technique; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D006801:Humans; D016876:Metal Ceramic Alloys; D015040:Zirconium
chemical_list: D016876:Metal Ceramic Alloys; D003776:Dental Porcelain; D015040:Zirconium; D000537:Aluminum Oxide; C028541:zirconium oxide