Journal of Dental Research, Vol 67, 585-587, Copyright © 1988 by International & American Associations for Dental Research Online Journals
Microleakage in class II composite restorations bonded to dentin using thermal and load cycling
P. A. Darbyshire, L. B. Messer and W. H. Douglas
Department of Pediatric Dentistry, School of Dentistry, University of Minnesota, Minneapolis 55455.
The effectiveness of a dentin-bonding agent (DBA) and a glass-ionomer
cement liner (GIC) in reducing the marginal microleakage at the cervical
margin of Class II posterior composite restorations was examined. The
effect of load cycling on microleakage of this type of restoration was
evaluated. The Class II cavities were prepared in extracted human pre-molar
teeth, with the cervical margins finished approximately 1 mm below the CEJ.
Combinations of DBA, GIC, and control (no liner) were used as mediators
between resin and dentin. All restorations were placed incrementally with a
40-second cure per increment and finished with high-speed diamond burs.
Half the samples of each treatment group received cyclical axial loading
and half did not. All samples were thermocycled at 5 degrees and 55 degrees
C for 500 cycles of one min each, stained (four hr) in 50% AgNO3, and
sectioned following stain development. Microleakage was scored linearly
along the dentin-restoration interface. All restorations exhibited
microleakage which was unaffected by load cycling. Both the DBA and the GIC
significantly reduced microleakage independently. When GIC was present, the
additional presence of the DBA did not provide a statistically significant
additional reduction of microleakage.
