[Set up of in vitro methods able to detect the safety of astringent liquids]

Most of dental operators agree about a gengival retraction impregnated cord in order to obtain an accurate and overwide dental impression. Hemostatic agents allow the formation of the primary coagulum that determines/causes the retraction of gum connective. Sometimes these astringent liquids cause local inflammation reaction as reported in literature. Aim of this work was the evaluation of the cytotoxic and inflammatory action of the most common astringent liquid on human gum primary cells by in vitro tests.

For this purpose primary cultures of normal human oral keratinocytes were established, following used either as monolayer or as reconstituted model. All dental preparations were dissolved in CEC medium, diluted to the designed concentrations and applied to the cultured cells. The cytotoxicity was determined by using MTT test, able to evaluate the succinate dehydrogenase activity and therefore the cell viability. Control cultures were treated with CED alone, whereas sodium dodecyl sulphate (SDS) was used as a positive control. Furthermore, the inflammatory response, determined by measuring TNF-alpha and IFN-gamma release, was evaluated on a reconstituted multilayer human oral epidermis model.

All agents tested showed a dose-dependent increase in the cytotoxicity to normal human gingival keratinocytes over the dose range examined. In particular the results obtained suggest the higher toxicity of the Astringedent X compound.

The results obtained from the present studies not only provide useful estimates of relative toxicities of these preparations to human oral mucose, but also can be useful as a standard for cytotoxic and inflammatory assessment of newly developed dental preparations to be topically applied to the oral mucosa. It is important to note, however, that the interpolation of these findings to in vivo conditions remains to be done.