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J Adv Prosthodont.  2016 Feb;8(1):30-36. 10.4047/jap.2016.8.1.30.

Influence of the preparation design and artificial aging on the fracture resistance of monolithic zirconia crowns

Affiliations
  • 1Danube Private University, Department for Posthetic Dentistry, Krems, Austria. gergo.mitov@dp-uni.ac.at
  • 2Danube Private University, Center for CAD/CAM and Digital Technologies, Krems, Austria.
  • 3Saarland University, Department for Posthetic Dentistry, Saarbrucken, Germany.
  • 4Charite-Universitatsmedizin Berlin, Department of Prosthodontics, Berlin, Germany.

Abstract

PURPOSE
The aim of this study was to evaluate the fracture resistance and fracture behavior of monolithic zirconia crowns in accordance with the preparation design and aging simulation method.
MATERIALS AND METHODS
An upper first molar was prepared sequentially with three different preparation designs: shoulderless preparation, 0.4 mm chamfer and 0.8 mm chamfer preparation. For each preparation design, 30 monolithic zirconia crowns were fabricated. After cementation on Cr-Co alloy dies, the following artificial aging procedures were performed: (1) thermal cycling and mechanical loading (TCML): 5000 cycles of thermal cycling 5degrees C-55degrees C and chewing simulation (1,200,000 cycles, 50 N); (2) Low Temperature Degradation simulation (LTD): autoclave treatment at 137degrees C, 2 bar for 3 hours and chewing simulation; and (3) no pre-treatment (control group). After artificial aging, the crowns were loaded until fracture.
RESULTS
The mean values of fracture resistance varied between 3414 N (LTD; 0.8 mm chamfer preparation) and 5712 N (control group; shoulderless preparation). Two-way ANOVA analysis showed a significantly higher fracture loads for the shoulderless preparation, whereas no difference was found between the chamfer preparations. In contrast to TCML, after LTD simulation the fracture strength of monolithic zirconia crowns decreased significantly.
CONCLUSION
The monolithic crowns tested in this study showed generally high fracture load values. Preparation design and LTD simulation had a significant influence on the fracture strength of monolithic zirconia crowns.

Keyword

Ceramics; Zirconia; In vitro; Tooth preparation; CAD-CAM

MeSH Terms

Aging*
Alloys
Cementation
Ceramics
Computer-Aided Design
Crowns*
Mastication
Molar
Tooth Preparation
Alloys
Ceramics
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