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Novel Irrigants for Canal Disinfection - Dr Liviu Steier- Courtesy ROOTS
The opinions within this web page are not ours. Authors have been credited for the individual posts and images where they are.
From: Rob Kaufmann
To: ROOTS
Sent: Saturday, July 01, 2006 4:05 AM
Subject: [roots] Summit Summary #3 - Dr. Liviu Steier - Novel Irrigants for Canal Disinfection

It would be one thing if Endo was all he did - but as Joey D said in his intro-
his restorative stuff is beyond compare. Just goes to show you what a brilliant
and talented guy Liviu is. Read on - you'll learn lots.

Dr. Liviu Steier
Mayen (Germany) and London (UK)
Novel Irrigants for Canal Disinfection

The goals of irrigation (both in the coronal AND apical third of the canal system are:

Debris and smear layer removal
Disruption of adhesive Biofilm
Disinfection
Opening of the Dentinal Tubuli

Should our disinfection/irrigation protocol be similar for all cases?
Dr. Steier believes that irrigation protocol can be divided into groups:

Acute AP and
Chronic AP
We need to address the irrigation protocol differently for different clinical situations.

Irrigation groups:

1. NaOCl
2. EDTA
3. Citric Acid
4. Chlorhexidine (CHX)
5. Factor "X"  (Electro Chemical Activation ECA of different solutions)

We must recognize the potential toxicity of NaOCl and the effects of ClO3- and ClO2- (the chlorates).
In mammals these chemicals arise from oxidative damage to red blood cells -> hemolytic anemia and
methaehemoglobin formation. It is also cytotoxic for fibroblasts. Therefore we are searching for
possible alternatives.

The new approach involves two areas of investigation:

Ozone
Electro Chemical Activation (ECA) (and not just ECA of H2O)

Irrigants of Interest:

Ozonized water
Ozonized NaOCl
ECA water
ECA NaCl (saline)
Ozonized ECA water
Ozonized ECA NaCl(saline)


Dr. Steier says that after 18 months the results are still being evaluated
but the Irrigation groups have changed to these 5 areas of interest:

Water
NaOCl
NaCl (saline)
Ozone
Electro Chemical Activation (ECA)


Ozone Generators are being produced but are not FDA approved. This is still years away. There is a big
difference between Ozone generating units. With the one design now available (the cheaper version),
ozone is liberated into the workspace and we know that ozone is toxic.    The newer designed unit
generates as much as 6 x the Ozone as another unit. Safety is assured by designing the unit to be
functional only when a vacuum is achieved over the endodontic access by means of an airtight "cap".
This seals the access when the ozone generating device is applied. Without the tight seal and without
a vacuum the machine will not deliver the ozone. Caps (8, 6, 5 and 4 mm sizes) are made of silicon
(and can therefore be customized by adding a silicone based material to them to make the airtight
connection to the tooth.)

ECA is a product of the 70's and was patented in the old Soviet Union by Dr. VM Bakhir. Since his papers
and ECA patents were published in Cyrillic (Russian) they have been difficult to publicly review.
This technology was first used for drilling. ECA fluids also have applications in endo preparation.
All ECA devices are more or less electrolysis of water or saline.

What do we put into this machine?

Water

Dr. Steier says that the quality of water that comes into our offices can vary from street to street,
even in the same city. In older dental units, biofilm problems (as a result of long term exposure to
these sources) can be a big problem.  Higher quality (cleaner) water can be obtained by:

Deionization
Distillation
Water quality is also affected by temperature of action and PH. Reverse Osmosis technology is used in
homes to improve water quality to that of the level of bottled water.

OZONE in Endodontics

The unit looks like a standard hand piece with a protruding needle and plastic cap that fits over the
access. The needle goes in the canal and provides the ozone. Dr. Steier's initial studies with this
device were disappointing and did not correspond to the manufacturer's claims.  Since Ozone is applied
as a gas, it can also be transported by a "carrier" media which may allow it to enter the deeper portions
of the canal system and hard tissue. He then studied Ozonized water, Ozonized ECA water and Ozonized
ECA NaCl (saline) as well as Ozonized NaOCl.

Dr. Steier showed that there have been many studies published on the use of Ozonization of solutions
with varying results.

The first studies used water:

Nagayoshi et al - Antimicrobial Effect of Ozonated Water on Bacteria Invading Dentinal Tubules

Ozonated water had nearly the same antimicrobial activity as 2.5% NaOCl during irrigation, especially
when combined with sonication and showed a low level of toxicity against cultured cells. *

*Dr. Steier says that this study used a generator that only produced 1/8th the ozone of the HealOzone
unit that he is currently testing. Therefore we must carefully scrutinize the results of these studies
i.e. / what solution did they use and what unit delivered the Ozone?

Cho et al - Disinfection of water containing natural organic matter (NOM) by ozone initiated radical
reactions.  (NOM is the term used to describe the complex mixture of organic material such as humic
acids, hydrophilic acids and hydrocarbons that are present in all drinking water.) The type of NOM
and the PH have considerable effects on the percentage of disinfection by hydroxyl radical, which
ranged from 20 to 50%.

This is important because dissolved impurities in modern water supplies (ions such as calcium, sodium,
chlorides etc.) can affect the properties of the ozone delivery. Ozonization of water by the cleavage
of humic acid, PROMOTES bacterial recontamination. Therefore the TYPE and SOURCE of water used in the
studies can actually promote recontamination if the "correct" type of water is not used.

One way to "clean" the water is by deionization. Deionization is a process that removes ions from the
water via ion exchange. Positively charged ions (cations) and negatively charged ions (anions) are
exchanged for hydrogen (H+) and hydroxyl (OH-) ions, respectively, due to greater affinity for other
ions.

Water quality is measured by measuring its electrical conductivity and electrical resistance. (It is the
amount of ionized substances (or salts) dissolved in the water that determines the water's ability to
conduct electricity. Poorer quality water has a lower resistance and conducts electricity better
better quality water has less ionized substances and conducts water less easily.) Most dental units have
very poor tasting water and the purity generally is actually not very high. Dental unit purity generally
falls slightly above of below the "city supply" purity level far from that of deionized or distilled
water (depending on location and age of unit.) Dr. Steier has introduced technologies to clean the water
in his dental units.

Reverse Osmosis units (for home use) use pressure and a membrane filter to remove impurities (ions) from
water. We also must understand that Distilled water reacts with atmospheric CO2, which brings the PH of
distilled water in an open air container down to a PH of about 5.8.

Liviu did a quick unscientific test using a TDS readout. (TDS (Total Dissolved Solids)= total amount of
mobile charged ions, minerals, salts or metals dissolved in a given volume of water  measured in ppm
parts per million). Distilled water had a value of 0 to 1.  His dental unit value was 239 and water line was 191.

In absence of dissolved electrolytes, water will not conduct electricity, so no electrolysis occurs.
This means that if we want to use this pure water  we will have problems.  This is why manufacturers
introduced saline for the electrolysis and to obtain the two (cation and anion) solutions.

Nagayoshi et al - Efficacy of ozone on survival and permeability of oral microorganisms
Ozonated water should be useful in reducing the infections caused by oral microorganisms in dental plaque.
Again, in their study they used a Neo Ozone Water-S unit that produced about 1/10th the ozone of a HealOzone unit.

Hems et al  An in vitro evaluation of the ability of ozone to kill a strain of E. faecalis.
There were significant reductions of bacteria in the unwashed and washed broth cultures following 240 seconds
of application. They concluded that Ozone had an antibacterial effect in planktonic E faecalis cells and those
suspended in fluid, but little effect when embedded in biofilms. Its antibacterial efficacy was not comparable
with that of NaOCl under test conditions used.  But Dr. Steier again points out that the tests used devices
and technology that produced low levels of ozone.

Electro Chemical Activation (ECA)

Definition: the process of passing a diluted saline solution through an FEM (Flow through Electrolytic Module)
in order to generate (by electrochemical energy conversion) environmentally friendly, highly active solutions
of anolyte and/or catolyte).  Electrolysis of water is what is known as a "redox" reaction. That means that
electrons are being moved from one molecule to another.

At the anode, electrons are removed from the water and it is oxidized  as in 2H2O O2+4H+4e-
At the cathode, electrons are added to the water as it is reduced  2H2O +4e-  2H2 + 4 OH-
So at the anode, we get oxygen gas and hydrogen ions, at the cathode we get hydrogen gas and hydroxide ions.

Dr. Steier points out that studies performed with ECA must be closely examined and scrutinized because the
solutions that are used in the studies can be very different  depending on the effects of the device used
for ECA AND the input solutions. Different FEMS can deliver different solutions.

ECA involves 2 processes:

Chemical processes
Electrical process ( done without additives)

Chlorine gas can be formed, if the electrodes in the unit are made of carbon. (Dr. Steier asks Joe Dovgan about
his Sterilox units and Joe says that he thinks they are made of Titanium.) It will only happened if NaCl is added
to the water, Cl ions in the water can oxidize to chlorine and combine with the OH ions to form Hypochlorite.
Cl2 + 2OH-  Cl- + OCl- + H2O.  The question is: What is the technology we are using? and what solutions are
being created?

Source Solutions for ECA

NaCl water solutions with no more than 5.0g/L concentration or fresh water of less than 1.0 g/L mineralization.
What is best for ECA?

Electro treatment

- is accompanied by controlled mass transfer in the inter-electrode space with minimal heat generation and with
obligatory creation of conditions for the closest contact of each microvolume of liquid under treatment with
the dense and/or diffuse part of the double electric layer in the electrode surface where the electric field
intensity reaches several million volts/cm.

Catolyte  is an anti-oxidizing, mild alkaline solution with a pH range of 10.5-12. The most common application
for the catolyte is as a mild cleaning, detergent and degreasing agent.

So by adding a sodium chloride solution to an ECA machine we get a "Metastable Solution" which has:

Changed pH of solution and high oxidation reduction potential
free radicals (High electron activity) in the catolyte
Extremely LOW electron activity in the anolyte.

(Dr. Steier reminded us that when we were discussing potential bonding of resin based endo filling materials
we need to have a reductant for the final irrigation. If we don't, the free oxygen radicals can inhibit
polymerization of the material.)

This "Metastable Solution" has excessive physical and chemical excitation.  This gradually dissipates with time
but - How long are the solutions stable?  They can be kept for 7 days as long as they are kept in Brown bottles
and stored in the refrigerator.

Anolyte- is a strong oxidizing solution with a pH range of 3.5-8.5. The most common application of anolyte
is as a biocidal agent.

FEM types:

Emerald Device mainly a technology to clean water of microorganisms, organic mixtures and heavy metal ions.
Used in the purification of drinking water.

Stel Device  used for synthesizing electrochemically activated washing, disinfectant and sterilizing solutions.
Mainly used in medical prevention and sanitary-epidemiological institutions. These devices deliver an anolyte
of two types: Acidic versions (pH<5) and Neutral versions (pH 6-8.)

The Catolyte produced is also of two types: an Neutral version (pH 7-0) and an Alkaline version (pH>9)

Aquachlor Device (the most Endodontically important devices) are used in the electrochemical synthesis of
gaseous oxidant mixture form NaCl aqueous solutions. The main components of the oxidant gaseous mixture are
molecular chlorine, chlorine dioxide and oxygen  found at a ratio of 70:20:5:5% respectively.  The ratio
depends on the particular device and can vary widely. Dr. Steier felt this had great potential because he
could increase the ozone production of the unit by ozonating the solution.

The most desired components from an anolyte are:

Free chlorine (ClO-)
H2O2 ( Hydrogen Peroxide)
O2
Ozone

Dr. Steier initially did his investigations with the Sterilox unit. But he shortly found out that the
technology used by Sterilox is actually an infringement of the intellectual property and patent originally
taken out by Dr. Bakhir. The construction of the unit and resultant solutions are not in keeping with the
original design parameters. The FEM anode plating is different resulting in less inadequate amounts of H2O2
that reduces the bacterial activities of one of the anolyte and leads to inefficient decontamination of
water in Emerald.

Because the Sterilox element is made of titanium, Dr. Steier says that we really don't know exactly what
kind of solutions are coming out of this machine.   He would prefer to see an Aquachlor technology based
device rather than a Stel or Emerald based device. Because ECA activated solutions were first used in the
drilling industry, he theorizes that (when ultrasonically activated) they may help us in our canal system
preparation.

Ozonization

It is important to remember that we wish to avoid the formation of chlorates. The mechanism of chlorate
formation is:

O3 (ozone) + OCl -> 2O2 +Cl-
O3 (ozone) + OCl -> O2 +ClO2-                Ionic Products of Ozonation of NaOCl
O3 (ozone) + OCl2 -> O2 +ClO3-

When NaOCl (at pH10-12) interacts with organic tissue it produces 3 reactions:

Saponification - resulting in the creation of lipids
Amino Acid Neutralization Reaction
Chloramination Reaction

These 3 reactions are important in the disinfection of the RCS.  Studies have shown that the Saponification
reaction occurs ONLY if we have enough free radicals. In our normal bleach solution, these free radicals are
not found in high amounts  so the solution is called "lazy" because of its low Saponification rate.

We want to use NaOCl solution at a pH of around 11 (where it is the most efficient) and where the maximum
amount of hypochlorous acid is present. Dr. Steier suggests that we measure the pH of our NaOCl irrigation
solutions to ensure maximum effect.

J.T. Marais - Cleaning efficacy of a new root canal irrigation solution: a preliminary evaluation.
The cleaning efficacy of electrochemically activated water in root canals was considered to be superior
to NaOCl producing cleaner surfaces and greater areas of smear layer removal.  (But technology used in the
study was unknown.)

Dr. Steier then cited several other studies that used various forms of ECA water:

Gulabivala et al - Effectiveness of ECA water as an irrigant in an infected tooth model

They concluded that there was a difference and that ultrasonication also was a factor. Steier said this
supported the reasons that the solutions were originally used for drilling.

Hata et al  JOE Dec 1996 Removal of Smear Layer in the Root Canal Using Oxidative Potential Water (OPW)
They found that OPW used as an irrigant was as effective as 5% NaOCl or 17% EDTA for opening and keeping
patent the dentinal tubules.

Hata et al IEJ June 2001- The Effectiveness of oxidative potential water as a root canal irrigant

This study concluded that OPW irrigation by syringe as effective as 5% NaOCl or 15% EDTA for removal of
smear layer and debris. The description of the technology again was different than that of the inventor,
Dr. VM Bakhir. SEM results showed the same results as in the JOE '96 study.

Dr. Steier's studies (in Belfast) included the following:

Ozonated water
0.5% NaOCl
0.5% NaOCl & Ultrasonics
Ozonated Anolyte

Ozonated Water (Ozone + water)

In the apical areas this solution really didn't do much. Smear layer and debris was present on the whole
surface.  In the area where the ozone delivering needle was placed, there was some minor improvement in
cleanliness. The more coronal areas were not cleaned at all.

0.5% NaOCl
In the coronal area not clean. Middle canal no effect. Same for Apical areas- not clean.

0.5% NaOCl & Ultrasonics
Some improvement and tubule patency was noted. The best cleaned areas again corresponded to the location
and depth of the ozone delivery tube.

Ozonated Anolyte
The coronal part showed improved cleanliness. The middle result showed less favorable results but the
apical portions showed bigger surfaces of cleaned dentin.

Dr. Steier says that although the results were not optimal, he needed to repeat the studies with a higher
concentration of NaOCl to see if the results were improved.

Further studies he later performed with Rimaldi and Beer - Antibacterial power of ozone activated
NaOCl for root canal disinfection (at Universitat Witten/Herdecke) used the following solutions

a.       5.25% NaOCl
b.      O.25 % NaOCl
c.       3 x 40" ozone activated 0.5% NaOCl
d.       3 x ozone activated cleaned deionized water

They concluded that Ozone activated NaOCl 0.5% had a higher antibacterial effect than unactivated
NaOCL 0.5%. The question is: What is the minimum concentration of NaOCl that we can use to get a good
effect while at the same time limiting the toxic effects of the solutions of higher strength?

OVERALL CONCLUSIONS

Two different NaOCl solutions should be used for endodontic treatment: One for Disinfection
and one for Smear Layer Removal.
For Disinfection  we still will use:
NaOCl 5.5 %
Ethanol (to reduce surface tension)
Elevate solutions to greater than 50 degrees C.
For Smear Layer Removal
NaOCl 5.5 % buffered to a pH of 11 (by using NaOH) AND making sure that the temperature
is around 10 degrees C.
Add H2O2 for at least 5 minutes - to avoid later chlorate formation  otherwise it could explode!
Add Ozone for 240 seconds then ultrasonically activated for 3 minutes.

How do we avoid chlorate formation?

The higher the pH the less chlorate (ClO3-) formation we will have.
H2O2 (Hydrogen Peroxide) by itself is a weak oxidant BUT it has a powerful synergistic effect when used
with Ozone.   ClO3- formation can be reduced by the addition of peroxide before Ozonization and allowing
sufficient time for the peroxide to react with the free chlorine. Add H2O2 for at least 5 minutes.
Decrease the temperature of the Ozonization liquid to about 10 degrees C.
Buffer the solution pH to about 11by adding NaOH.

Dr Steier says that we now have a different set of irrigants to use. These include:

NaOCl
EDTA
Citric Acid
CHX
Ozone

The remaining question for the near future is: Which ECA technology will fit the needs of Endodontic therapy
in the best manner?  Dr. Steier sees the Aquachlor technology using Bakhir's FEM design
(joint venture with a US company) as the best prospect for the future.


END

Summit 2005  Summary by
Rob Kaufmann DMD MS(Endo)

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