Irrigation

Effect of Citric acid

• Excellent filling results after preparation with citric acid (20%), followed by 2.6% sodium hypochlorite and a final flushing with 10% citric acid.

• Wayman et al. (1979)

Chelating Agents

Chelating Agents

• EDTA (ethylene-diaminetetra-aceticacid)
• EDTAC (ethylene-diaminetetra-aceticacid ¢rimide)
• File-Eze
• RC Prep

EDTA

EDTA

• EDTA (17%, disodium salt, pH 7)
• EDTA has little if any antibacterial activity.
• It effectively removes smear layer by chelating the inorganic component of the dentine.
• Aid in mechanical canal shaping.

EDTA

• The ultrastructure on canal walls after EDTA and combined EDTA & NaOCl irrigation was evaluated by scanning electron microscopy.
• More debris was removed by irrigation with EDTA followed by NaOCl than with EDTA alone.

• Niu et al. (2002)

• The optimal working time of EDTA is 15 minutes, after which time no more chelating action can be expected.
• EDTA solutions should replaces in the canal each 15 minutes.

• Goldberg and Spielberg (1982)

• The optimal pH for the demineralizing efficacy of EDTA on dentin was shown by Valdrighi (1981) to be between 5.0 and 6.0.276
• Goldberg and Abramovich (1977)have shown that EDTAC increases permeability into dentinal tubules, accessory canals, and apical foramina.

• Coronal portion of canal of in vivo endodontically treated tooth with EDTAC. The tubules are open, and the canal is clean and free of smear. B, Filed canal treated with EDTAC.Longitudinal section of dentinal tubules shows thin intertubular matrix.

• McComb and Smith(1975) found that EDTA (in its commer- cial form, REDTA), when sealed in the canal for 24 hours, produced the cleanest dentinal walls
• Goldman et al. (1981) have shown that the smear layer is not removed by sodium hypochlorite irrigation alone but is removed with the combined use of REDTA.

• Removal of the smear layer is an important step to facilitate disinfection of the root canal. Both EDTA and citric acid can effectively remove the smear layer created during canal instrumentation. Although citric acid may also have an antibacterial effect, this has not been compared with other root canal disinfecting agents in in vitro or in vivo studies.