In vitro cytotoxicity of diverse preparations used in dental practice to human gingival keratinocytes.

The cytotoxicities of diverse preparations used for dental practice were examined with normal human keratinocytes from gingival tissues by the uptake of neutral red (NR assay). Cultures from different individuals were established, and secondary cultures in serum-free medium were used. The cytotoxicities to cells treated for 2 days with gargles, mouthwashes, gingival massages, fluoride preparations, dentifrices and local anaesthetics were determined from the dose-response curves of inhibition of NR uptake. As a quantitative measure of cytotoxicity, NR(50) (the concentration of the preparations that resulted in a 50% decrease in NR uptake relative to untreated controls) was interpolated from dose-response curves. Dentifrices examined showed cytotoxicity similar to gingival massages but were more cytotoxic than any fluoride preparations, local anaesthetics, and most gargles and mouthwashes. The cytotoxicities of dentifrices were at least 6.5-fold those of fluoride preparations and 7.9-fold those of local anaesthetics. The results provide useful estimates of relative toxicities of dental preparations to human oral mucosa and are useful as a standard for cytotoxic assessment of newly developed preparations for dental use.

[Cytotoxicity of dental iodine glycerin on cultured mammalian cells].

Cytotoxicity of dental iodine glycerin was studied using cultured Chinese hamster lung cells (V79 cells). Treatment with dental iodine glycerin at 0.33 - 0.1v/v% for 24 to 72 hr elicited a minor inhibition of growth of V79 cells. The cell growth, however, was remarkably inhibited when the cells were treated with dental iodine glycerin at 0.3v/v%. No inhibitory effect on survival of V79 cells was observed in cultures treated with dental iodine glycerin at 0.03 - 0.1v/v% for 2 to 24 hr. Meanwhile, treatment with dental iodine glycerin at 0.3v/v% for 2 hr or more induced 100% inhibition of cell survival. Exposure of cells to dental iodine glycerin at 0.3v.v% for 2 hr caused decrease in DNA, RNA or protein synthesis of the cells up to 54.4% of untreated cells. These results indicate that there is a big difference in cytotoxicity induced by treatment of V79 cells with dental iodine glycerin at concentrations between 0.1v/v% and 0.3v.v%, and that treatment with dental iodine glycerin induced inhibition of DNA, RNA and protein synthesis of the cells and the inhibition occurs even by the treatment which causes no reduction of cell survival.