Impact of thermal properties of veneering ceramics on the fracture load of layered Ce-TZP/A nanocomposite frameworks.
OBJECTIVE
The aim of this in vitro study was to assess the influence of thermal properties of veneering ceramics on the fracture load of layered ceria stabilized zirconia/alumina nanocomposite (Ce-TZP/A) single crowns.


METHODS
Ce-TZP/A single crown frameworks (nanoZr) were veneered with 5 different veneering ceramics for zirconia (Cerabien ZR, IPS e.max, Triceram, Vintage ZR, VM9). In addition, veneering ceramics for alumina (Allux) and for the metal-ceramic technique (Reflex) were included in order to cover a wide range of coefficients of thermal expansion. Fracture load of the crowns was assessed in a shear test (n=10). Glass transition temperatures (T(g)) of the ceramics as well as the coefficients of thermal expansion of the ceramics (alpha(veneer)) and Ce-TZP/A (alpha(core)) between 25 and 500 degrees C were determined (n=6).


RESULTS
Fracture load ranged from 574.0+/-97.1N (IPS e.max) to 1009.6+/-150.0N (VM9). Deltaalpha=alpha(core)-alpha(veneer) and DeltaT=T(g)-25 degrees C (DeltaT in K) were calculated. The fracture load was strongly correlated to Deltaalpha DeltaT with a maximum at Deltaalpha DeltaT approximately 580 x 10(-6).


CONCLUSIONS
The overall fracture load of veneered Ce-TZP/A crowns is correlated to the thermal properties of the respective veneering ceramic.
Fischer
Jens
J
Clinic for Fixed and Removable Prosthodontics, Center for Dental and Oral Medicine, University of Zurich, Zurich, Switzerland. jens.fischer@zzmk.uzh.ch
Stawarczyk
Bogna
B
Trottmann
Albert
A
Hämmerle
Christoph H F
CH
D000537:Aluminum Oxide / Q000737:chemistry*; D002516:Ceramics / Q000737:chemistry*; D002563:Cerium / Q000737:chemistry*; D003442:Crowns; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D003801:Dental Veneers; D005898:Glass / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry; D053761:Nanocomposites / Q000737:chemistry*; D033081:Shear Strength; D013314:Stress, Mechanical; D013696:Temperature; D013816:Thermodynamics; D044366:Transition Temperature; D015019:Yttrium / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry*
C475766:Ce-TZP-Al2O3; D003764:Dental Materials; C508050:IPS e.max Press; D016876:Metal Ceramic Alloys; C096474:Vintage Porcelain; C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; D002563:Cerium; D015019:Yttrium; D015040:Zirconium; D000537:Aluminum Oxide