Previous studies have shown that light-polymerized denture base resins have a cytotoxic effect on oral epithelial cells. The purpose of this in vitro study was to examine the effects of two denture base resin sealants when used on three light-polymerized denture base resins. Sample disks were examined for their effect on protein synthesis. Results indicate that one sealant protected the cells against toxic effects of the materials (P .05), while one sealant enhanced toxicity up to 88% above that attributed to the resin alone.