Journal of Dental Research, Vol 63, 1327-1331, Copyright © 1984 by International & American Associations for Dental Research Online Journals
Effect of metal design on marginal distortion of metal-ceramic crowns
P. H. DeHoff and K. J. Anusavice
An analysis of residual stress and marginal distortion due to thermal
contraction mismatch between metal and ceramic is presented for
metal-ceramic crowns. Using dilatometric data, finite element stress
analyses were performed on pre-molar crowns designed with chamfer-knife
edge, chamfer with collar, shoulder with collar, and shoulder-bevel with
collar geometries and a maxillary central incisor crown with a
chamfer-knife edge geometry. Calculations were made using combinations of a
Ni-Cr alloy or a Au-Pd alloy with each of three porcelain products.
Calculated marginal distortions due to crown design and metal-porcelain
thermal contraction incompatibility were found to be well below
experimental values found in the literature. For the cases studied, the
calculated marginal distortions due to metal-porcelain thermal contraction
mismatch depend primarily on the metal-porcelain combination and are
insensitive to the coping design. However, this study excluded copings
which have been extensively ground to thicknesses of 0.1 mm or less, and
such copings may be more susceptible to localized or generalized
distortion.
