In contrast to calcium hydroxide, both CHX - and octenidine-based intracanal medicaments were effective in decreasing the viability of E. faecalis. OCT showed the most favourable results and may have potential as an endodontic medicament.

The interactive effect of combinations of the Fusarium mycotoxins deoxynivalenol (DON), zearalenone (ZEA) and fumonisin B 1 (FB 1 ) on growth of brewing yeasts was examined. Yeast growth was assessed by measurement of dry weight or relative growth, cell number, viability and conductance change of the growth medium using direct and indirect methods. The interactive effect of a combination of these mycotoxins was subject to the ratio of toxins in the mixture and the toxicity of individual toxins on yeast growth. When a combination of mycotoxins at low concentration was added into the growth medium, no significant inhibitory effect on growth was observed compared to controls. However, when a combination of high concentrations of DON and ZEA which individually inhibited yeast growth was examined, the interactive effect was shown to pass from antagonism to synergism depending on the ratio of the toxins in the mixture. As a synergistic interaction between these Fusarium mycotoxins was observed only at high concentrations, which were far higher than would be expected in good quality grain, they are not a concern when related to yeast growth under the brewing conditions studied.

Tlte effect of the trichothecene mycotoxins deoxynivalenol (DON) and nivalenol (NIV) on growth of Saccharomyces cerevisiae lager and ale strains has been studied. Tlte toxins were added into tlte growth medium in low and high concentrations. Yeast growth was assessed by measurement of dry iveight or relative growth, cell number, viability and conductance change of the growth medium using direct and indirect methods. Tlte inhibitory effect of both DON and NIV on yeast growth was dependent on toxin concentration. Additionally, when tlte extent of inhibition of yeast growth caused by high concentrations of both toxins was observed, it was subject to yeast strain, length of incubation and method used to assess yeast growth. Tlte lowest concentrations of mycotoxin causing significant inhibition on growth of brewing yeasts were: 100 \iglml DON for the lager strain and 50 \iglml for the ale strain, and 50 \ig/ml NIV for the ale strain.

The Fusarium mycotoxins zearalenone (ZEA) andfumonisin B7 (FBj) added to the growth medium in low and high concentrations, were investigated as a possible cause of inhibition ofgrowth of Saccharomyces cerevisiae lager and ale strains. Toxic effects were assessed by measurement of dry weight or growth relative to controls, cell number, viability and conductance changes of the growth medium using indirect and direct methods. Hie Fusarium mycotoxins studied affected growth on brewing yeasts, but the inhibitory effect was dependent on concentration. Low concentrations (0.1-2 \iglml) had no significant effect on growth compared to controls. Although high concentrations of both mycotoxins strongly affected growth, the inhibitory effect depended on toxin concentration and type, yeast strain, length of incubation and method used to assess growth. The lowest concentrations ofmycotoxin causing significant inhibition on growth of these brewing yeasts were 50 \iglml ZEA for both yeast strains, and 10 \ig/ml FBj for the lager strain and 50 [ig/mlfor the ale strain.

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