Eliminating the infecting bacteria of the root canal system and preventing reinfection must be the main objectives of all endodontic works. None of commercially available root canal sealers have the properties of desirable tissue compatibility and strong antibacterial activity. The purpose of this study is to develope an ideal root canal sealer using commercially available polyphosphate (polyp), Calgon, which is known to be antibacterial and safe. For the study, resin-type AH26, zinc oxide eugenol-type Tubli-Seal, Ca(OH)₂-type Apexit as base sealers for polyp (0~3%) and para formaldehyde-containing N2 as a control base were selected. Specimens (3x4mm) of the sealers were prepared in a 37℃ incubator for 3 and 10 days and their antibacterial activity against streptococci and black-pigmented anaerobic rods was observed using an agar diffusion method. The result were as follows":
1. Among 3-day-old root canal sealers, N2 as a positive control showed the strongest antibacterial effect, followed by AH26. Tubli-Seal and. Apexit which barely showed antibacterial activity against the test bacteria. In contrast, 10-day-old AH26 showed a greater antibacterial activity than 10-day-old N2.
2. All sealer specimens showed a greater antibacterial activity against black-pigmented anaerobic rods than streptococci. Three-day-old ones appeared to be more antibacterial than 10-day-old ones except for Apexit.
3. As compared to N2, 3-day-old AH26 demonstrated a similar antibacterial activity against black-pigmented anaerobic rods but to a lesser extent to streptococci. Ten-day-old AH26 showed a greater antibacterial activity against black-pigmented anaerobic rods than 10-day-old N2.
4. As compared to AH26. Tubli-Seal generally revealed a lower antibacterial activity but it showed a greater antibacterial activity aginst S. gordonii Challis.
5. Enhancement of antibacterial activity by polyp was more clearly observed when it was added to Ca(OH)²- based root canal sealers. Tubli-Seal and N2.
6. The addition of polyp enhanced the antibacterial activity of 3-day-old AH26 against S. gordonii G913 (16%) and Challis (29%), and P. gingivalis 2561 (24%) only. Moreover, polyp failed to increase antibacterial activity of 10-day-old AH26 against the test strains but P. gingivalis A7A1-28 (13%).
7. The addition of polyp increased the antibacterial effect of 3-day-old Tubli-Seal on several test bacteria including S. mutans GS-5 (50%). S. gordonii G913 (47%) and Challis (122%). and all the test strains of P. gingicalis (13~35%) except for 9-14K-1. The addition of polyp to 10-day-old Tubli-Seal increased antibacterial activity of the root canal sealer against most test strains.
8. 3-day-old Apexit failed to show antibacterial activity, if any very little against S. mutans GS-5 and Pr. intermedia ATCC 49046. However, polyp increased its antibacterial activity by 50 and 69%, respectively. Increase of antibacterial activity of 10-day-old Apexit by polyp was more clearly observed than that of 3-day-old one.
The overall results suggest that polyp may be used in clinic as an antibacterial agent in root canal sealers. However, in order to maximize its antibacterial effect, the composition of sealers should be considered.
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