Allan Deutsch
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 ECENTLY,
several new articles have been published that add valuable information
as to which irrigant to use and for how long. Currently, I use the following
protocol:
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I irrigate with 5.25 percent sodium hypochlorite into the canals and leave
some irrigant in the pulp chamber when using all the stainless steel SafeSiders,
from size #08 to size #40.
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I change the irrigating solution in the canals and in the pulp chamber
every time I change the instrument size.
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When I reach the NiTi SafeSiders (30/.04 and 25/.08), I flood the canals
(which have already been opened with the number 2 Peeso, with 17 percent
EDTA in an aqueous solution.
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I now intrument the final canal shape with the EDTA in the canal and the
NiTi SafeSiders. This will remove the smear layer and open up the
dentinal tubules.
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After instrumentation, I give the canal a final rinse with 5.25 percent
hypochlorite to remove and neutralize the 17 percent EDTA.
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I dry and fill the canals next.
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However, if this is a retreatment, or if there has been a longstanding
infection (longer than 3 months), I will now irrigate with 0.12 percent
chlorhexidine (Peridex®). I let the chlorhexidine sit in the
canals for approximately five minutes.
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After five minutes, I dry the canals with paper points and fill the canals
with GP and cement. I do not irrigate with NaOCl.
In a study reported in the International Endodontic
Journal, N. Habahbeh, et al, reported that all concentrations of NaOCl
were effective in the elimination of E. faecalis but that different concentrations
required different lengths of time to achieve the result; 5.25
percent was the most effective, killing 100 percent of bacterial cells
in two minutes. The time required by 2.5, 1.0 and 0.5 percent
was 5, 10 and 30 minutes respectively.1
In another study, L. M. Sassone, et al, showed that
0.12 percent chlorhexidine (CHX) did not eliminate E. faecalis in
any
time interval. One percent CHX eliminated all strains, as did NaOCl
at both 1 percent and 5 percent concentrations. Therefore, under the conditions
of this study, a 0.12 percent CHX solution was ineffective at killing E.
faecalis.2
A third study, reported by O. Oncag, et al, compared
the antibacterial properties and toxicity of 5.25 percent NaOCl, 2 percent
chlorhexidine gluconate, and 0.2 percent chlorhexidine gluconate plus 0.2
percent cetrimide (Cetrexidin®: Vebas, San Giuliano, Milan, Italy).
In the laboratory study, the 2 percent CHX gluconate and Cetrexidin were
significantly more effective on E. faecalis than the 5.25 percent NaOCl
at 5 minutes. Similarly, in the in vivo study, 2 percent CHX
gluconate and Cetrexidin were significantly more effective on anaerobic
bacteria than the 5.25 percent NaOCl at 48 hours. The authors state
that “2 percent CHX gluconate and Cetrexidin had more antibacterial effect
on anaerobic bacteria than 5.25 percent NaOCl because of their active cationic
properties, which enable their adsorbtion by the dentine surface and their
substantive antibacterial effect.”3 It is surmised that
this cationic effect leaves a long-acting antibacterial action on the dentinal
tubules.
After reading these articles I must now say “Oops!”
My NaOCl protocol is OK. I am certainly leaving
my 5.25 percent solution in the canal for greater than two minutes.
This will kill almost all the bacteria and remove the tissue debris and
consequently the organic load. However, I am certainly not leaving
the 0.12 percent chlorhexidine Peridex (Figure 1, left) in the canal long
enough. According to the article by L. M. Sassone, et al, 0.12
percent CHX would never entirely get rid of the bacteria, no matter how
long you left it in the canal! To get rid of 100 percent of the bacteria
within five minutes you need a solution of CHX greater than 1 percent.
Consequently, I have now bought 2 percent
chlorhexidine by Vista (Figure 1, right). I have retained the same
protocol as above with the exception of using 2 percent chlorhexidine instead
of 0.12 percent.
Let’s hope this kills all those bugs!
References
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Habahbeh N, Drucker DB, Qualtrough JE, Korachi M. Abstract R95. International
Endodontic Journal 2003;36(12):950.
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Sassone LM, Fidel R, Fidel S, Vieira M, Hirata R, Jr. The influence of
organic load on the antimicrobial activity of different concentrations
of NaOCl and chlorhexidine in vitro. International Endodontic Journal 2003;36(12):848-852.
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Oncag O, Hosgor M, Hilmioglu S, Zekioglu O, Eronat C, Burhanoglu D. Comparison
of antibacterial and toxic effects of various root canal irrigants. International
Endodontic Journal 2003;36(6):423-432.
February-March 2004
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FIGURE 1: 0.12 percent chlorhexidine
from Peridex and 2 percent chlorhexidine from Vista.
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