Materials and Methods
The irrigation protocol used in this clinical study included the alternating use of a citric acid “50%” chelating solution, distilled water and chlorhexidine 0.12 or 0.2%.
One of the most important factors prior to instrument removal is the creation of a reservoir coronal to the separated fragment in order to receive the liquid.3
This reservoir can be created with the use of modified gates glidden drills, #1 and #2 sectioned at their maximum cross-sectional to obtain a flat end and a predictable caliber (gg1=50, gg2=70), and an LA access bur (Sybron Endo) of appropriate size. The objective here is to create straight line access to the coronal aspect of the separated fragment for predictable removal as well as to provide a reservoir to hold an adequate volume of solution.
Sodium hypochlorite is probably the most widely used irrigant for root canal preparation.5
For this procedure sodium hypochlorite is not recommended because this irrigant targets organic tissue and not the inorganic tissue that is meant to be demineralized in this situation. Citric acid has been recommended as a canal irrigant because of its ability to demineralize and to remove the smear layer6 which is thought to be mostly inorganic. Wayman et al.6 showed that 10,25, and 50% solutions of citric acid were all effective in removing calcium when used as a root canal irrigant. The demineralization effect of citric acid is apparently very rapid. Using dentinal discs, it has been shown that a 6% solution of citric acid required only 5s to remove much of the smear layer and exposed the orifices of the dentinal tubules.6,8,9 The distilled water is used to wash out the citric acid and the chlorhexidine acts as an antimicrobial agent.
