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J Prosthet Dent. 2013 Mar;109(3):165-71. doi: 10.1016/S0022-3913(13)60037-2.

Fracture toughness of yttria-stabilized zirconia sintered in conventional and microwave ovens.

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1
Department of Restorative Dentistry, College of Dentistry, University of Illinois, Chicago, IL, USA. aristotelismarinis@yahoo.com

Abstract

STATEMENT OF PROBLEM:

The fabrication of zirconium dioxide (ZrO2) dental prosthetic substructures requires an extended sintering process (8 to 10 hours) in a conventional oven. Microwave sintering is a shorter process (2 hours) than conventional sintering.

PURPOSE:

The purpose of this study was to compare the fracture toughness of 3 mol % Y2O3-stabilized ZrO2 sintered in a conventional or microwave oven.

MATERIAL AND METHODS:

Partially sintered ZrO2 specimens from 3 manufacturers, KaVo, Lava 3M, and Crystal HS were milled (KaVo Everest engine) and randomly divided into 2 groups: conventional sintering and microwave sintering (n=16 per group). The specimens were sintered according to the manufacturers' recommendations and stored in artificial saliva for 10 days. Fracture toughness was determined by using a 4-point bend test, and load to fracture was recorded. Mean fracture toughness for each material was calculated. A 2-way ANOVA followed by the Tukey HDS post hoc test was used to assess the significance of sintering and material effects on fracture toughness, including an interaction between the 2 factors (α=.05).

RESULTS:

The 2-way ANOVA suggested a significant main effect for ZrO2 manufacturer (P<.001). The post hoc Tukey HSD test indicated that mean fracture toughness for the KaVo ZrO2 (5.85 MPa·m(1/2) ±1.29) was significantly higher than for Lava 3M (5.19 MPa·m(1/2) ±0.47) and Crystal HS (4.94 MPa·m(1/2) ±0.66) (P<.05) and no significant difference was observed between Lava 3M and Crystal HS (P>.05). The main effect of the sintering process (Conventional [5.30 MPa·m(1/2) ±1.00] or Microwave [5.36 MPa·m(1/2) ±0.92]) was not significant (P=.76), and there was no interaction between sintering and ZrO2 manufacturer (P=.91).

CONCLUSIONS:

Based on the results of this study, no statistically significant difference was observed in the fracture toughness of ZrO2 sintered in microwave or conventional ovens.

PMID:
23522365
DOI:
10.1016/S0022-3913(13)60037-2
[Indexed for MEDLINE]
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