In vitro evaluation of antimicrobial activity of sealers and pastes used in endodontics

The antimicrobial activity of four root canal sealers (AH Plus, Sealapex, K etac Endo, and Fill Canal), two calcium hydroxide pastes (Calen and Calasep t), and a zinc oxide paste was evaluated. Seven bacterial strains were used , six of them standard; Micrococcus luteus ATCC 9341, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Staphylococcus epidermidis ATCC 12228, Escherichia coli ATCC 25922, and Enterococcus faecalis ATCC 105 41. There was a wild strain of Streptococcus mutans isolated from saliva ob tained in an adult dental clinic. Activity was evaluated using the agar dif fusion method with Brain Heart Infusion agar and Muller Hinton medium seede d by pour plate. Calcium hydroxide-based sealers and pastes were either pla ced directly into 4.0 x 4.0 mm wells or by using absorbent paper points. Th e plates were kept at room temperature for 2 hr for diffusion. After incuba tion at 37 degrees C for 24 hr, the medium was optimized with 0.05 g% TTC g el and inhibition haloes were measured. All bacterial strains were inhibite d by all materials using the well method. However, when the materials were applied with absorbent paper points, Enterococcus faecalis was not inhibite d by zinc oxide, and Pseudomonas aeruginosa was not inhibited by AH Plus, F ill Canal, and the zinc oxide-based paste. We conclude that sealers and pas tes presented antimicrobial activity in vitro and culture medium optimizati on with 0.05 g% TTC gel facilitated observation of the inhibition haloes.