title: In vivo fracture resistance of implant-supported all-ceramic restorations.
abstract: BACKGROUND
  Because of their specific mechanical properties, all-ceramic restorations demonstrate a lower fracture resistance than ceramic restorations supported by metal substructures. However, advances have been made in the fabrication of high-strength all-ceramic abutments for anterior implants. No previous study has compared the fracture loads between 2 different all-ceramic abutments restored by glass-ceramic crowns.
  
  
  OBJECTIVE
  The purpose of this in vitro investigation was to quantify the fracture load of implanted-supported Al(2)O(3) and ZrO(2) abutments restored with glass-ceramic crowns.
  
  
  METHODS
  Two ceramic abutments were tested: an Al(2)O(3) abutment (CerAdapt) and a ZrO(2) abutment (Wohlwend Innovative). The abutments (n = 10) were placed on Brånemark dental implants and prepared for restoration with glass-ceramic crowns (IPS Empress). After fabrication, in accordance with the manufacturer's guidelines, the crowns were bonded to the all-ceramic abutments with a dual-polymerizing resin luting agent. The fracture loads (N) were determined by force application at an angle of 30 degrees by use of a computer-controlled universal testing device. The data were analyzed with the unpaired t test (alpha=.05).
  
  
  RESULTS
  Statistical analysis showed significant differences between both groups (P=.001) of all-ceramic abutments, with mean fracture load values of 280.1 N (+/- 103.1) for the Al(2)O(3) abutments and 737.6 N (+/- 245.0) for the ZrO(2) abutments.
  
  
  CONCLUSIONS
  Within the limitations of this study, both all-ceramic abutments exceeded the established values for maximum incisal forces reported in the literature (90 to 370 N). The ZrO(2) abutments were more than twice as resistant to fracture as the Al(2)O(3)-abutments.
authors.affiliation: Department of Prosthodontics, University of Aachen, Medical Center, Pauwelsstr. 30, 52074 Aachen, Germany. myildirim@ukaachen.de
authors.forename: Murat
authors.initials: M
authors.lastname: Yildirim
authors.forename: Horst
authors.initials: H
authors.lastname: Fischer
authors.forename: Rudolf
authors.initials: R
authors.lastname: Marx
authors.forename: Daniel
authors.initials: D
authors.lastname: Edelhoff
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry*; D003442:Crowns; D000044:Dental Abutments; D015921:Dental Implants; D003764:Dental Materials / Q000737:chemistry; D003776:Dental Porcelain / Q000737:chemistry; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D005898:Glass / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D019279:Resin Cements / Q000737:chemistry; D013314:Stress, Mechanical; D016474:Weight-Bearing; D015040:Zirconium / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D015921:Dental Implants; D003764:Dental Materials; C075815:IPS-Empress ceramic; D019279:Resin Cements; D003776:Dental Porcelain; D015040:Zirconium; D000537:Aluminum Oxide; C028541:zirconium oxide