The first part of this study reviewed the characteristics of calcium hydroxide (Ca(OH)₂) and summarized the results of in vitro studies related to its antimicrobial effects. The second part of this review covers in vivo studies including human clinical studies and animal studies. The use of Ca(OH)₂ as an intracanal medicament represented better histological results in animal studies. However, human clinical studies showed limited antimicrobial effects that microorganisms were reduced but not eliminated through the treatment, and that some species had resistance to Ca(OH)₂. Most of clinical outcome studies supported that there is no improvement in healing of periapical lesions when Ca(OH)₂ was applied between appointments. Further studies are required for the antimicrobial effects of Ca(OH)₂, and search for the ideal material and technique to completely clean infected root canals should be continued.

The goal of endodontic treatment is the prevention and control of pulpal and periradicular infections. Calcium hydroxide (Ca(OH)₂) has been widely used in endodontics as an intracanal medicament to eliminate the remaining microorganisms after chemomechanical preparation. The purpose of this article is to review the antimicrobial properties of Ca(OH)₂ as an intracanal medicament in root canal treatment. The first part of this review details the characteristics of Ca(OH)₂ and summarizes the results of in vitro studies related to its antimicrobial effect. The antimicrobial effect of Ca(OH)₂ results from the release of hydroxyl ions when it comes into contact with aqueous fluids. Ca(OH)₂ has a wide range of antimicrobial effects against common endodontic pathogens, but is less effective against Enterococcus faecalis and Candida albicans. The addition of vehicles or other agents might contribute to the antimicrobial effect of Ca(OH)₂.

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.