The purpose of this study was to assess the antibacterial effect of sodium dichloroisocyanurate (NaDCC), sodium hypochlorite (NaOCl), and chlorhexidine (CHX) on Enterococcus faecalis and to evaluate and to compare the time-dependant antimicrobial effect of NaDCC with NaOCl and CHX in the root canal in vitro before and after instrumentation.

Extracted human single teeth were prepared by serial instrumentation technique. The samples were autoclaved and contaminated for 3 days with E. faecalis monocultures. The teeth were then divided into 4 groups. Each group was irrigated and inserted with 2% NaOCl, 2% NaDCC, 2% CHX and sterilized saline. After 6, 12, 24, 72h, and 1 week incubation, sterilized paper point was inserted into the root canal. Paper points containing root canal contents were then placed on the agar plate. And then each root canal was prepared with #4 and #5 GG (Gates-Glidden) drill. The debris were collected in the sterilized microtube and the plates were incubated at 37℃ in an increased CO₂ atmosphere. After 24h incubation the growth of bacteria around the paper points were measured.

NaOCl and NaDCC solution shows similar antimicrobial effect for E. faecalis at 6, 12, 24, 72h and 1 week. In control group, irrigated with sterilized saline, no antimicrobial effect was observed.

The results are in agreement with other investigators, who have shown the bactericidal property and possibility of NaDCC as a root canal irrigation solution. Thus it seems that NaDCC solutions can be clinically applied into the root canal within 1 week after dilution.

The purpose of this study was to evaluate the clinical applications of the Sodium Dichloroisocyanurate effervescent tablet as a routine root canal irrigant by performing several in vitro tests such as Cl^- content, cytotoxicity, antimicrobial effect as well as its pH level compared to the equivalent concentration of sodium hypochlorite solution.

Sodium Dichloroisocyanurate demonstrated lower level of Cl^- concentation than each dilution of sodium hypochlorite solution. Both solution has increased level of Cl^- as the concentration of each solution increased. There was no significant change of Cl^- concentration in sodium hypochlorite as time goes by. However, Cl^- concentration in Sodium Dichloroisocyanurate was increased.

As results, Sodium Dichloroisocyanurate solution fully satisfy the basic requirements as a root canal irrigation solution. However, we strongly recommend to use this solution clinically in low concentration and try to apply into the root canal within 1 week after dilution.