title: Loading capacity of zirconia implant supported hybrid ceramic crowns.
abstract: OBJECTIVE
  Recently a polymer infiltrated hybrid ceramic was developed, which is characterized by a low elastic modulus and therefore may be considered as potential material for implant supported single crowns. The purpose of the study was to evaluate the loading capacity of hybrid ceramic single crowns on one-piece zirconia implants with respect to the cement type.
  
  
  METHODS
  Fracture load tests were performed on standardized molar crowns milled from hybrid ceramic or feldspar ceramic, cemented to zirconia implants with either machined or etched intaglio surface using four different resin composite cements. Flexure strength, elastic modulus, indirect tensile strength and compressive strength of the cements were measured. Statistical analysis was performed using two-way ANOVA (p=0.05).
  
  
  RESULTS
  The hybrid ceramic exhibited statistically significant higher fracture load values than the feldspar ceramic. Fracture load values and compressive strength values of the respective cements were correlated. Highest fracture load values were achieved with an adhesive cement (1253±148N). Etching of the intaglio surface did not improve the fracture load.
  
  
  CONCLUSIONS
  Loading capacity of hybrid ceramic single crowns on one-piece zirconia implants is superior to that of feldspar ceramic. To achieve maximal loading capacity for permanent cementation of full-ceramic restorations on zirconia implants, self-adhesive or adhesive cements with a high compressive strength should be used.
authors.affiliation: Institute for Dental Materials and Engineering, University Hospital for Dental Medicine, University of Basel, Hebelstrasse 3, CH-4056 Basel, Switzerland. Electronic address: nadja.rohr@unibas.ch.
authors.forename: Nadja
authors.initials: N
authors.lastname: Rohr
authors.affiliation: VITA Zahnfabrik, 79713 Bad Säckingen, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Coldea
authors.affiliation: Department for Periodontology, Endodontology and Cariology, University of Basel, Hebelstrasse 3, 4056 Basel, Switzerland.
authors.forename: Nicola U
authors.initials: NU
authors.lastname: Zitzmann
authors.affiliation: Institute for Dental Materials and Engineering, University Hospital for Dental Medicine, University of Basel, Hebelstrasse 3, CH-4056 Basel, Switzerland; VITA Zahnfabrik, 79713 Bad Säckingen, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Fischer
mesh_terms: D000134:Acid Etching, Dental; D000538:Aluminum Silicates / Q000737:chemistry*; D002516:Ceramics / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D017076:Computer-Aided Design; D003442:Crowns; D003738:Dental Cements / Q000737:chemistry*; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D055119:Elastic Modulus; D008422:Materials Testing; D017680:Potassium Compounds / Q000737:chemistry*; D013499:Surface Properties; D013718:Tensile Strength; D015040:Zirconium / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D003188:Composite Resins; D003738:Dental Cements; D017680:Potassium Compounds; C016447:feldspar; D015040:Zirconium; C028541:zirconium oxide
keywords: CAD/CAM crown; Compressive strength; Fracture load; Hybrid ceramic; Resin composite cement; Zirconia implant