Toxicity of visible light-cured denture resins

Abstract

In this study three commercial formulations of visible light-cured (VLC) denture resins have been analyzed. The products used are those suggested for the reline, repair and fabrication of dentures to improve their fit. The biocompatibility of these resins was investigated by measuring RNA and DNA synthesis of oral epithelial cells in vitro. The extent to which oral cells recover from toxic resin exposure, the conversion of monomer into polymer, the presence of inorganic filler, and resin leacha~ility have also been studied. It was shown that VLC denture resins inhibit the synthesis of RNA and· DNA relative to a heat-cured resin control (p~0.05). Although epithelial cells appeared to recover from toxic resin exposure, this recovery was inconsistent among experiments. Infrared spectroscopy illustrated chemical group differences that occurred before and after photo-polymerization. Using these differences, the conversion of monomer into polymer ranged from 77% to 97%. This conversion was significantly affected (p< .003) by the type of curing unit, duration of photo-polymerization, and surface exposed to visible light. Soluble substances in cured and uncured resin products were analogous using HPLC. The range of inorganic filler present was 0-15%. These investigations suggest that visible light-cured denture resins may impair the replication of oral epithelial cells. This effect may be related to the leachability of unpolymerized resin constituents, the presence or absence of filler particles, or polymerization by-products.