Disinfection by calcium hydroxide pastes of dentinal tubules infected with two obligate and one facultative anaerobic bacteria.

Bovine dentine cylinders were experimentally infected with Actinomyces israelii, Fusobacterium nucleatum, or Enterococcus faecalis. The latter is a facultative anaerobic bacteria and the others are obligate anaerobes commonly found in endodontic infections. The infected specimens were exposed to pastes of calcium hydroxide mixed with saline solution or camphorated paramonochlorophenol for periods of 1 h, 1 day, and 1 week. The viability of bacteria after these exposure times was evaluated by specimen incubation in culture medium to compare the effectiveness of the pastes in disinfecting dentinal tubules. The calcium hydroxide/camphorated paramonochlorophenol paste effectively killed bacteria in the tubules after a 1-h period of exposure, except for E. faecalis that required one day of exposure. In contrast, the calcium hydroxide/saline paste was ineffective against E. faecalis and F. nucleatum even after 1 week of exposure. The results showed that camphorated paramonochlorophenol increased the antibacterial effects of calcium hydroxide.