EFFECT OF ESTERASE ON METHACRYLATES AND METHACRYLATE POLYMERS IN AN ENZYME SIMULATOR FOR BIODURABILITY AND BIOCOMPATIBILITY TESTING

Current in vitro biocompatibility methods do not evaluate the degradat ion of biomaterials after contact with enzymes that might be present i n the oral or systemic environment. In this study, two methods of in v itro enzyme degradation and a method for the separation of the degrada tive products by high performance thin-layer chromatography (HPTLC) ar e reported. In the first method two dental adhesives, Scotchbond and S cotchbond II, and two dental composites, Heliomolar and P-50, were eva luated. These materials were incubated with four different enzymatic p reparations for periods of up to 72 h. The enzymes were Lipase, estera se, and Liver enzyme extracts from both mouse and rat. Chloroform solu ble products extracted from the aqueous phase were examined by HPTLC f or decomposition products resulting from enzyme activity. The second m ethod was similar, but analyzed the aqueous fraction directly without chloroform extraction. In this method five dental restorative material s, P-50, P-30, Scotchbond II, Silux, and Silux plus, were incubated wi th a nonspecific porcine liver esterase. In addition to the polymerize d biomaterials, monomers containing methacrylic acid units were also h ydrolyzed with esterase and analyzed by ion chromatography to establis h the sensitivity of the enzyme simulator. Each biomaterial presented thin-layer zones not present before enzymatic action. These experiment s provide support that aqueous enzymatic action may facilitate the hyd rolytic weakening of polymeric biomaterials. (C) 1994 John Wiley and S ons, Inc.