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Role of Core Support Material in Veneer Failure of Brittle Layer Structures



Ilja Hermann, Sanjit Bhowmick, Brian R. Lawn


A study is made of veneer failure by cracking in all-ceramic crown-like layer structures. Model trilayers consisting of a 1 mm thick external glass layer (veneer) joined to a 0.5 mm thick inner stiff and hard ceramic support layer (core) by epoxy bonding or by fusion are fabricated for testing. The resulting bilayers are then glued to a thick compliant polycarbonate slab to simulate a dentin base. The specimens are subject to cyclic contact (occlusal) loading with spherical indenters. Video cameras are used to record the fracture evolution in the transparent glass layer in situ during testing. The dominant failure mode is cone cracking in the glass veneer, by traditional outer (Hertzian) cone cracks at higher contact loads and by inner (hydraulically pumped) cone cracks at lower loads. Failure is deemed to occur when one of these cracks reaches the veneer/core interface. The advantages and disadvantages of the alumina and zirconia core materials are discussed in terms of mechanical properties strength and toughness, as well as stiffness. Consideration is also given to the roles of interface strength and residual thermal expansion mismatch stresses in relation to the different joining methods.
Journal of Biomedical Materials Research


alumina, cone cracks, cyclic fatigue, dental crowns, residual stress, slow crack growth, zirconia


Hermann, I. , Bhowmick, S. and Lawn, B. (2006), Role of Core Support Material in Veneer Failure of Brittle Layer Structures, Journal of Biomedical Materials Research, [online], (Accessed April 23, 2024)
Created September 26, 2006, Updated February 19, 2017