Journal of Dental Research, Vol 71, 1633-1639, Copyright © 1992 by International & American Associations for Dental Research Online Journals
Early bond strength of luting cements to a precious alloy
P. Mojon, E. B. Hawbolt, M. I. MacEntee and P. H. Ma
Department of Clinical Dental Sciences, University of British Columbia, Vancouver, Canada.
Previous studies have reported that glass-ionomer and adhesive resin
cements can bond to various alloys, while zinc phosphate cements lack this
adhesive property. This study evaluated the bonding properties of three
luting cements during the first seven days after cementation. Thirty
cylinders were cast with a high-noble porcelain-fused-to-metal (PFM) alloy
and luted in pairs with one of the cements. The joints were stored in water
at 37 degrees C for one, two, or seven days before being fractured in
shear. The cylinders were re-used to provide 40 joints within each test
group. The data were subjected to a Weibull analysis, a curve-fitting
method shown to be appropriate for comparing the bond strengths of dental
materials. The results showed that the zinc phosphate cement was the
weakest material, whereas the adhesive resin produced the strongest joints.
Microscopic observations of the fractured samples did not reveal any
specific differences between the samples in terms of their mechanism of
fracture. The glass-ionomer cement reached its maximum bond strength after
two days, whereas storage time had no influence on the zinc phosphate
cement. The adhesive resin cement was slightly, but not significantly,
weaker after one week in water. We suggest that excessive loading of
restorations cemented with glass ionomer should be avoided for the first
two days after the placement. The use of an adhesive resin cement can be
recommended on endodontically treated teeth, but further studies are needed
to evaluate its biocompatibility and adhesion to dentin.
