Characterization of damage modes in dental ceramic bilayer structures

Abstract

Results of contact tests using spherical indenters on flat ceramic coating layers bonded to compliant substrates are reported for selected dental ceramics. Critical loads to produce various damage modes, cone cracking, and quasiplasticity at the top surfaces and radial cracking at the lower (inner) surfaces are measured as a function of ceramic-layer thickness. It is proposed that these damage modes, especially radial cracking, are directly relevant to the failure of all-ceramic dental crowns. The critical load data are analyzed with the use of explicit fracture-mechanics relations, expressible in terms of routinely measurable material parameters (elastic modulus, strength, toughness, hardness) and essential geometrical variables (layer thickness, contact radius). The utility of such analyses in the design of ceramic/substrate bilayer systems for optimal resistance to lifetime-threatening damage is discussed.

Design maps for failure of all-ceramic layer structures in concentrated cyclic loading

“…Moduli were obtained using a routine ultrasonic method (Grindosonic MK5, J.W. Lemmens Inc., St Louis, MO) [5]. Single-cycle strengths of each core material were measured from critical contact loads to induce bottom surface radial cracks in ceramic/polycarbonate bilayer specimens constructed as above with abraded ceramic undersurfaces but without the veneer, i.e.…”

“…For radial cracks, the net thickness d is the controlling variable, with the characteristic flexural d 2 dependence in P R in Eq. (3) [5,8]. Relative thickness is not an important factor within the range 0.25 < d v /d c < 0.75 (see Eq.…”

“…Considerable recent work has been done on the way brittle layer structures consisting of a weak and relatively compliant "veneer" joined to a strong and stiff "core" and glued to a polymeric base fail in contact loading with spheres [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Such configurations are representative of occlusal loading of all-ceramic veneer/core dental crowns fixed to tooth dentin [18][19][20][21].…”

Laboratory Simulation of Y-TZP All-ceramic Crown Clinical Failures

“…Fracture strengths have been progressively increased from glassceramic (Empress II, 320 MPa) to alumina (547 MPa) to zirconia (900 MPa) (Deng et al, 2002). The high value found for the latter, similar to that of metals such as steel (Manicone et al, 2007), has encouraged its use for hip and knee replacements and dental crowns, fixed partial dentures (FPD), and implants (Kohal and Klaus, 2004;Kohal et al, 2006).…”

Influence of Layer Thickness on Stress Distribution in Ceramic-Cement-Dentin Multilayer Systems

“…With this testing system, contact damage modes have been identified as cone cracking (brittle mode) and/or micro-deformation yield (quasi-plastic mode) on the surface of layered ceramic structures, and as radial cracking at the subsurface of the top layer 2,5,7,8) . These damage modes have been reported in many investigations, beginning with monolayer ceramic systems 2,5,6) , and proceeding to bilayer [8][9][10][11] and trilayer [11][12][13] systems with dentin-like substrate materials. Further on fracture damage studies, tests investigating coating/substrate mismatch (in terms of moduli of elasticity) 8,10,12,14) and thicknesses of these layers 8,10,12) have been conducted.…”