Journal of Dental Research, Vol 63, 1335-1340, Copyright © 1984 by International & American Associations for Dental Research Online Journals
Measurement of oxide adherence to PFM alloys
J. R. Mackert Jr, E. E. Parry, D. T. Hashinger and C. W. Fairhurst
A method has been reported for evaluating adherence of an oxide to its
substrate metal to a maximum value of about 40 MPa. Oxidized alloy plates
were cemented between two aluminum cylinders with a high-strength
cyanoacrylate cement and loaded in tension until failure occurred either at
the oxide/metal interface, within the oxide layer, or in the cement itself.
Significant differences were found among the oxide adherence values
obtained from different PFM alloys. The oxides formed on five of the alloys
exhibited adherence strengths in excess of the published value for cohesive
strength of dental opaque porcelain, indicating that they possess
sufficient adherence to act as the transition zone between the porcelain
and the alloy. In addition, a correspondence was found between the quality
of porcelain bond for a given alloy and its oxide adherence strength. These
results remove the principal objection to the oxide-layer theory of
porcelain bonding in dental alloy systems and emphasize the importance of
oxide adherence in the establishment of a bond. It is therefore suggested
that future work devoted to porcelain-metal bonding should seek to
elucidate the mechanism of oxide adherence to PFM alloys and explore the
development of new alloys which form adherent oxides.
