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

Objectives: To eliminate microorganisms that are responsible for pulpal and periapical infections and to prevent reinfection of the root canal system an effective chemomechani- cal 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. Materials and Methods: A total of 120 human single-canalled anterior teeth were select- ed. 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 gut- ta-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. Results: Residual antimicrobial activity of MTAD in the teeth obturated with gutta- percha/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. Conclusion: MTAD had antimicrobial activity even at the sixth week, although it had a time-dependent decrease. Resilon/Epiphany SE significantly decreased antimicrobial ac- tivity of MTAD at all time points.