Cell responses to Hydron by a new in-vitro method.

An in-vitro biotoxicity test system, suitable for the assessment of endodontic filling materials, has been developed and used to test cell responses to Hydron, AH26 and Tubliseal. A robust, well-characterized and stable cell line (L-cells) which was grown as uniform cultures on Millipore filters, has been used as indicator cells. As they approached confluence they were exposed to test substances for 24 h and biosynthetic activities were measured. The test system is a modification of that described by Wennberg et al. (1979). By inverting the cultures on organ-culture rafts, cells were separated from the test material, which was placed on top of the Millipore filters. Freshly mixed polymerizing Hydron and prepolymerized Hydron were tested. The cell responses were compared with those of cultures exposed to freshly mixed AH26 and Tubliseal. Polymerizing and prepolymerized Hydron depressed both cell division, assessed by 3H-thymidine incorporation, and the synthesis and secretion of matrix material as measured by precipitable 35S-sulphate. Prepolymerized Hydron decreased cell functions by 59% and 56% of live cell controls, respectively, while the freshly mixed polymerizing Hydron inhibited biosynthesis by 89% and 94%, respectively. The data for polymerizing Hydron were compared with results for other root-filling materials and showed similar values to those for Tubliseal (92% and 95%), but greater inhibition of biosynthesis than for AH26 (53% and 50%). The AH26 values were similar to those obtained from cultures exposed to the prepolymerized Hydron. Recovery of biosynthetic capacity by these cultures after removal of all endodontic material was also assessed. Partial biosynthetic recovery of cell cultures was observed 24 h after removal of preopolymerized Hydron.(ABSTRACT TRUNCATED AT 250 WORDS)