Evaluation of Antimicrobial Effect of MTA Mixed with Various Concentrations of Iodine Potassium Iodide on Different Microorganisms with Direct and Indirect Methods

MTA is one of the most commonly used materials in endodontics. Antimicrobial effect is one of the ideal properties of a root-end filing material. The aim of this study was to evaluate the antimicrobial activity of MTA mixed with 1%, 2% and 4% IKI with the use of direct and indirect methods.
In this experimental study, direct contact test (DCT) was used to evaluate the antimicrobial effect of set MTA, mixed with different concentrations of IKI and distilled water against Enterococcus faecalis, Staphylococcus aureus and Candida albicans, in 30-minute, 1-hour and 24-hour intervals. Colony forming units (CFU/mL) were determined. The agar diffusion test (ADT) (the indirect technique) was used to assess the antimicrobial activity of fresh MTA mixed with 1%, 2% and 4% IKI and distilled water against the microorganisms above. The diameter of the zone of inhibition was measured by calipers. Data were analyzed with SPSS 17, using one-way ANOVA and Kruskal-Wallis, Mann-Whitney and Tukey tests (α = 0.05).
DCT method showed that the antimicrobial activity of MTA mixed with 2% and 4% IKI against E. faecalis, S. aureus and C. albicans at 24-hour interval was significantly higher than other concentrations (p value = 0.021). Antimicrobial activity of MTA mixed with 1% IKI was the same as that of MTA mixed with distilled water, with no significant difference (p value = 951). In the indirect method, the antimicrobial effects of MTA mixed with 4% IKI against C. albicans (p value = 0.038) and S. aureus (p value = 0.042) were significantly higher than other concentrations. Various concentrations of IKI mixed with MTA did not exhibit significant antimicrobial properties against E. faecalis compared to mixing with distilled water (p value = 0.864).
IKI at 1% and 4% concentrations in the direct method and 4% IKI in the indirect method exhibited higher antimicrobial activity than other concentrations.