Margin failures in crown-like brittle structures: Off-axis loading
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The effect of off-axis loading of compliant indenters on the initiation of cracks at the margins of dental crown-like dome structures consisting of glass shells back-filled with an epoxy resin is examined. As in previous studies on similar structures but with strictly axial loading, cracks can be made to initiate and propagate from the margins around the dome faces into a "semi-lunar" fracture pattern characteristic of some all-ceramic crown failures. In this study, balsa wood and teflon disk indenters are used to provide the off-axis loading, at 45° to the dome axis. The soft indenters, considered representative of food bolus, spread the contact at the top surface, suppressing otherwise dominant radial cracks that ordinarily initiate at the dome undersurface directly along the load axis beneath harder indenters. Finite element modeling is used to show that off-axis loading dramatically increases the tensile stresses at the near-side dome margin, strongly diminishing the loads required to generate the lunar fracture mode.
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The role of skirt geometry of dental crowns on the mechanics of failure: Experimental and numerical studyWhitton, A.; Qasim, T.; Ford, Christopher; Hu, X.; Bush, M. (2008)Dental crown structures were modelled using a curved bi-layer system consisting of a brittle glass coating on a compliant polymeric substrate, to illustrate the role of skirt geometry on the mechanics of failure evolution. ...
Keown, A.; Bush, M.; Ford, Chris; Lee, J.; Constantino, P.; Lawn, B. (2012)An experimental simulation study is made to determine the effects of occlusal wear on the capacity of teeth to resist fracture. Tests are carried out on model dome structures, using glass shells to represent enamel and ...
Ford, Christopher; Bush, M.; Lawn, B. (2009)Finite element analysis is conducted on a tooth model with different degrees of wear. The model is taken as a hemispherical shell (enamel) on a compliant interior (dentin). Occlusal loading is simulated by contact with a ...