Novidades do Século Passado

1. The success or failure of root canal treatment depends on elimination of these microorganisms.

2. Calcium hydroxide has been recommended as an intracanal medicament for total elimination of microorganisms (Bystro¨m et al. 1985). However, some studies show that calcium hydroxide may not ensure total elimination of microorganisms (Safavi et al. 1990, Ørstavik et al. 1991).

3. Bacteria resident in dentinal tubules, apical anatomy of root canal systems and isthmuses may not be completely eliminated by root canal treatment procedures (Siqueira 2001, Peters et al. 2002, Nair et al. 2005).

4. The remaining bacteria may be killed by the antibacterial activity of the sealer (Kaplan et al. 1999, Siqueira et al. 2000, Peters & Wesselink 2002) or they may be deprived of nutrition and space to multiply (Sundqvist & Figdor 1998).

5. Sundqvist & Figdor (1998) suggested that one of the goals of root canal filling is the entombment of remaining bacteria in the root canal system. Entombing of bacteria within the root canal system should result in all remaining bacteria being sealed by the root filling in dentinal tubules, lateral canals, apical rami- fications and in the isthmuses so as to prevent their communication with the periodontium (Wu et al. 2006)

6. Root canal sealers should provide a seal and have antibacterial activity (Grossman 1980).

7. Saleh et al. (2004) showed that AH Plus in root fillings killed all bacteria in the dentinal tubules within a 300 lm zone around the root canal, but RoekoSeal had limited antibacterial effect against E. faecalis.

8. Most root canal sealers have antibacterial components. (Geurtsen & Leyhausen 1997).

9. Peters & Wesselink (2002) claimed that the presence of positive culture at the time of root filling did not affect the outcome of endodontic therapy. The data from the present study demonstrated that residual bacteria may be rendered uncultivable within the test zone around the root filled canal, especially if a sealer with strong antibacterial activity, such as AH Plus, is used.

10.  Selection of a root canal sealer may be more important than the root canal filling method for elimination of bacteria.