Abstract
Staining and subsurface degradation of dental composites were studied in a clinical trial and associated laboratory experiments. The materials in the clinical trial were Clearfil Posterior, Occlusin, and P-30. A significantly higher proportion of Occlusin restorations exhibited marginal stain. An in vitro study indicated that the clinical practice of curing the unfilled bonding resin prior to placing the composite caused the formation of a resin interface with the potential to stain. Bonding resins containing hydrophilic monomers such as HEMA stained more than resins based on BIS-GMA/TEGDMA.
In restorations which had been removed for replacement, P-30 exhibited a significantly higher depth of subsurface degradation as assessed by silver nitrate staining. In vitro studies indicated that this material was more permeable and leached more inorganic ions than the other materials. It is suggested that, in clinical practice, the thickness of the bonding resin should be kept to a minimum, and that modem materials with soluble glass fillers should be investigated so that the effects of these fillers on permeability and degradation can be observed.
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