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INTRODUCTION The immediate noticeable manifestation of halitosis is caused by the presence of volatile sulfur compounds (especially H2S), volatile organic acids, and volatile amines in the breath. The major cause of malodor being the volatile sulfur compounds, which have intensely unpleasant odors even at very low concentrations. These compounds are produced by the action of anaerobic microorganisms on proteins that contain the sulfur containing amino acids cysteine and methionine. One mechanism by which the Oxyfresh "Stabilized Chlorine Dioxide" containing mouthrinse products operate to eliminate halitosis is by the oxidation of the odoriferous volatile sulfur compounds into non-volatile, non-odoriferous molecules such as the corresponding sulfates, sulfonates, and sulfones. Therefore, one possible experimental procedure to evaluate the effectiveness of the Oxyfresh "Stabilized Chlorine Dioxide" based mouthrinse products is to test their effectiveness at oxidizing volatile sulfur compounds. The successful removal of the volatile sulfur compounds will eliminate the symptoms of bad breath until the H2S concentration is regenerated above a
threshold level due to the metabolic processes of
the indigenous microbiological flora. The ability of "Stabilized Chlorine Dioxide" to combat the root cause of bad breath by reducing the population of odor causing anaerobic microorganisms was not investigated as a part of the study herein described and will not be addressed at this
time.
EXPERIMENTAL PROCEDURE Hydrogen sulfide gas in nitrogen and air at concentrations of about 300-400 ppb were bubbled through a fine glass frit into 60mL of an aqueous sample that was to be tested for its ability to decrease the concentration of H2S in the gas stream. The gas stream emerging from the test sample was directed into a Halimeter (Interscan Corp) which measures the H2S concentration of the gas stream. The Halimeter is essentially an
electrochemical detector specifically designed for
the detection of H2S at the ppb level. First, the H2S level was measured after passing through a distilled water control and
then it was measured after passage through various
Oxyfresh "Stabilized Chlorine
Dioxide" based mouthrinse products. During a
series of tests, a water control was run about every four samples
to ensure against any systematic error.
The sample of Oxyfresh New Fresh Flavor Mouthrinse
used in all of these experiments was a production sample (Lot
#02261) taken before the peppermint oil was added. It was tested
without the peppermint oil to eliminate any possibility that the
volatile mint component could interfere with the electrochemical
measurement of the hydrogen sulfide by the Halimeter.
In this experiment H2S concentrations
were recorded after 1, 2, 3, 4, and 5 minutes after the gas flow
through the mouthrinse samples were begun.
RESULTS
The numbers in
the tables below all have
units of parts per billion (ppb) H2S.
After One (1) Minute Exposure Time
DISCUSSION
The data above shows that:
(1) Both Oxyfresh New Mint mouthrinse
and Oxyfresh Natural Mouthrinse reduce the hydrogen sulfide (H2S)
level significantly below that of a water control.
The water control simply establishes
the base line level of the H2S
gas in the gas stream. The water control should remove only small
amounts of H2S due
to a finite solubility of the H2S gas in water.
(2) Oxyfresh New Mint Mouthrinse is
significantly more effective than Oxyfresh Natural Mouthrinse
at reducing the H2S
concentration even though the concentration of "Stabilized
Chlorine Dioxide" is the same in both products. This difference
in effectiveness is greater after one minute than after five minutes.
A possible explanation for the greater
efficacy of the New Mint Mouthrinse over the Natural Mouthrinse
is that the presence of the additional ingredient, xylitol, decreases
the surface tension of the water and allows more surface area
contact between the aqueous "Stabilized Chlorine Dioxide"
and the H2S
gas. The xylitol itself certainly does not directly remove H2S.
It must just serve in some way (probably by decreasing surface
tension, as stated above) to facilitate the oxidation of the H2S
by "Stabilized Chlorine Dioxide"'.
CONCLUSION
These in vitro experiments clearly
show that Oxyfresh "Stabilized Chlorine Dioxide" based
mouthrinse products significantly reduce the level of H2S
in a gas stream under the experimental conditions employed.
In these in vitro experiments,
the contact time between a bubble of gas (H2S
in air) and the aqueous "Stabilized Chlorine Dioxide"
solution was only between 1-2 seconds. In
addition, the chemistry that occurs between the "Stabilized
Chlorine Dioxide" in the water, and the H2S
in the gas stream, only occurs at the water/bubble surface interface.
The fraction of the bubble mass that is present at this interface
is dependent upon the bubble size, but it is certainly less than
one, and in some cases maybe as small as 0.01.
Therefore, the results of these
experiments suggest that "Stabilized Chlorine Dioxide"
must be very effective at oxidizing H2S
in order to be able to reduce the H2S
level from about 350 ppb to about 150 ppb under the severe constraints
of contact time and fractional contact mass encountered in this
experiment.
Even though the ability of "Stabilized
Chlorine Dioxide" to oxidize H2S
in the oral cavity of human beings was not performed at this time,
there is every reason to expect that it will be as effective at
oxidizing H2S
in the mouth of humans as it has shown itself to be at oxidizing
H2S in
the in vitro experiments described above. After all, the
laws of chemistry are the same in vivo and in vitro.
And actually,
since the directions for using the Oxyfresh mouthrinse products
call for a one minute contact time, then, when used as
directed, it seems reasonable to conclude that, under the conditions
of longer contact time and greater mixing, essentially all of
the H2S
in the oral cavity at the time of use would be removed.
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