residual antimicrobial activity of mtad(®) in human dentin after obturation with gutta-percha/ah26 and resilon/realseal se at different time intervals; an ex vivo study.

to eliminate microorganisms that are responsible for pulpal and periapical infections and to prevent reinfection of the root canal system an effective chemomechanical preparation by irrigants with sustained antimicrobial activity is beneficial. hereby, we evaluated the residual antibacterial activity of mtad after canal obturation at different time intervals.a total of 120 human single-canalled anterior teeth were selected. the root canals were instrumented to a standardized apical size. among all, 90 teeth received final irrigation with mtad and were divided into three groups according to their obturation materials; i.e. gutta-percha/ah26, resilon/realseal se and positive controls. all these groups were divided into three 1-, 3- and 6-week time interval subgroups. thirty teeth as negative control had no final irrigation with mtad, but were obturated with gutta-percha/ah26 or resilon/realsealse. dentin powder was prepared after 1, 3 and 6 weeks. dentin powder was exposed to enterococcus faecalis for 24h and then cultured. colony forming unit (cfu) was counted.residual antimicrobial activity of mtad in the teeth obturated with guttapercha/ah26 was significantly higher than the teeth obturated with resilon/realseal se (p<0.001). it also showed a time dependent decrease in mtad antimicrobial activity for all groups. the highest antimicrobial activity of mtad was found in the 1-week positive control and 1-week gutta-percha/ah26 specimens. the lowest antimicrobial activity of mtad was found in 6-week resilon/realseal se samples and then the negative controls.mtad had antimicrobial activity even at the sixth week, although it had a time-dependent decrease. resilon/epiphany se significantly decreased antimicrobial activity of mtad at all time points.