Influence of cyclic loading on the fracture toughness and load bearing capacities of all-ceramic crowns.

Rao-rao Wang; Cheng-lin LU; Gang Wang; Dong-sheng Zhang

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Influence of cyclic loading on the fracture toughness and load bearing capacities of all-ceramic crowns.

Author: Rao-Rao WANG ¹ ; Cheng-Lin LU ² ; Gang WANG ³ ; Dong-Sheng ZHANG ⁴
Author Information

1. The Tenth People's Hospital of Tongji University, Shanghai, China.
2. Weigao Orthopaedic Device Co., Ltd., Weihai, China.
3. Laboratory for Microstructures, Shanghai University, Shanghai, China.
4. 1] Department of Mechanics, Shanghai University, Shanghai, China [2] Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai, China.
Publication Type:Journal Article
MeSH: Crowns; Humans; Mastication; Materials Testing
From: International Journal of Oral Science 2014;6(2):99-104
CountryChina
Language:English
Abstract: The purpose of this study was to investigate how cyclic loading influenced the fracture toughness of hot-press lithium disilicate and zirconia core materials and whether there was an increase in the propensity for crown failure. Two types of all-ceramic crowns including the IPS e.max Press system (n=24) and the Lava zirconia system (n=24), were selected. Sectioned specimens were subjected to cyclic loading with the maximum magnitude of 200 N (R=0.1) until two million cycles. The material properties including Young's modulus (E) and hardness (H) and the fracture toughness (KIC) of the core materials were evaluated using indentation methods (n=12 each). The load-bearing capacities of the specimens were examined by means of monotonic load to fracture (n=12 each). It was found that the material properties, including E, H and KIC, of the two types of dental ceramics, were reduced. Statistical analysis indicated that there were no significant influences of fatigue loading on material properties E and H for both types of dental ceramics or KIC for zirconia, while for the IPS e.max Press core, KIC, which was parallel to the direction of the lithium disilicate crystals, was significantly reduced (P=0.001). A conclusion was drawn that zirconia possesses high mechanical reliability and sustainable capacity to resist fatigue loading, while fatigue loading remarkably degraded the anisotropic mechanical behaviour of hot-press lithium disilicate ceramics.