Research Article
Effect of Mouth Rinses with and without Alcohol on Halitosis: Randomized Crossover Controlled Trial Employing Gas Chromatography
Ribeirão Preto, Jeronimo Manço de Oliveira Neto, Wendel Teixeira, Raony Môlim de Sousa Pereira, Cássio do Nascimento and Vinícius Pedrazzi*
Department of Dental Materials and Prosthesis, School of Dentistry of Ribeirão Preto, University of São Paulo, Brazil
*Corresponding author: Vinícius Pedrazzi, Department of Dental Materials and Prosthesis, School of Dentistry of Ribeirão Preto, University of São Paulo, Brazil
Published: 20 Aug, 2018
Cite this article as: Preto R, de Oliveira Neto JM,
Teixeira W, de Sousa Pereira RM, do
Nascimento C, Pedrazzi V. Effect of
Mouth Rinses with and without Alcohol
on Halitosis: Randomized Crossover
Controlled Trial Employing Gas
Chromatography. Clin Surg. 2018; 3:
2082.
Abstract
Halitosis is a disease that negative limpactsy people's lives. This single centre, randomized, crossover
controlled trial compared: Periogard® with alcohol (positive control) (CHXw/a) and without alcohol
(CHXn/a); Listerine Total® (EOw/a) and Listerine ZeroTM (EOn/a) arranged into four sequences
of use. 21 volunteers with intra-oral halitosis used each product at once, followed by a one-week
washout period. The breath was measured by portable gas chromatograph OralChromaTM before
rinsing and after 1, 2 and 3 hrs. Compared to the baseline, at the first hour, only EOw/a was able
to significantly reduce the breath (H2S p<0.0001 and CH3SH p=0.001) for both gases and its effect
lasted for up to three hours (H2S p<0.0001 and CH3SH p=0.001). CHXw/a (control) reduced H2S
at the first hour (p=0.001) and lasted for three hours (H2S p<0.0001) without effect on CH3SH.
CHXn/a just reduce H2S levels. EOn/a had no effect on breath, which increased with time for both
gases. It can be indicated the essential oil based product containing alcohol and zinc chloride more
efficiently with the proviso that only essential oils are approved for continuous use. The EOw/a
presented the best performance against intra-oral halitosis followed by the control CHXw/a and
CHXn/a.
Keywords: Halitosis; Mouth rinses; Gas chromatography; Crossover controlled trial
Introduction
Halitosis is an unpleasant condition for both the carrier and for the persons with whom it relates to be cause of a social constraint and to possibly precipitate a neurosis. The tongue coating, being a bacterial mass formed by squamous epithelial cells, salivary proteins and protein remains food metabolized by proteolytic bacteria, gives a foul smelling compound called Volatile Sulfur Compounds (VSCs) such as hydrogen sulfide (H2S), dimethyl sulfide (CH3)2S [1] and methyl mercaptan (CH3SH) [2-5]. Hydrogen sulfide (H2S) is a colorless, flammable and water soluble characterized by the smell of rotten eggs. Methanethiol or methyl mercaptan is also a mouth breath odorivector with recognition threshold about 1/30 that of H2S with a much higher odour potential than H2S, indicating that MM causes odor problems at much lower concentrations than H2S, and may also be produced by methylation of hydrogen sulfide as a detoxification mechanism by mucosal thiol S-methyltransferase [2-4]. Given the importance of H2S to the physiological process and whereas values above 112ppb from this gas can be detected by the human sense of smell with an unpleasant odor, as well as methanethiol at 26ppb, it is common sense to attempt the elimination or reduction of these compounds in breath by local routes, using products in the oral cavity, without systemic interference. Strategies for controlling bad breath is related to control of the growth of bacteria, especially proteolytic, and engages the teeth and tongue cleaning in combination with the use of antimicrobials [5]. Therefore, a variety of products has been used in an attempt to inhibit or mask bad breath odor, including tongue sanitizers, agents in chewing gum, toothpaste and mouthrinses. The primary concern leading to the frequent use of mouthrinses is halitosis [6]. According to Loesche in 1999 [7], the first clinical trials with rinses against oral malodor were designed with a cosmetic claim [8-13]. Therefore, recent studies show the importance of comparative trials to determine the true efficacy of the use of mouthwash [14-16]. Healthy individuals who complain of bad breath have used mouthwash containing masking or antimicrobial agents [11,17,18]. Many products with different formulations and mechanisms of action have been proposed in order to help against halitosis, among them we can mention: cetylpyridinium chloride, triclosan, chlorhexidine gluconate, chlorine dioxide, stannous fluoride, essential oils, lactate, citrate zinc chloride [7,14,19-22]. Some products are used to reduce oral malodor by chemical neutralization of VSC. The active ingredients of these products are often metal ions and oxidizing agents. Metals such as zinc, sodium, tin and magnesium are considered for interacting with sulfur. The interaction forms insoluble sulfides. The proposed mechanism is that the metal ions oxidize thiol groups in the precursors of VSC [23,24]. The oxidizing agents can reduce oral malodor by reducing the necessary conditions for the metabolism of sulfur-containing amino acids [25]. Although there are a large number of studies evaluating the effect of these products on halitosis, there is still much disagreement between the results and their actual effectiveness. A recent Cochrane review on this topic concluded that randomized controlled trials comparing the effectiveness of available mouth rinses are needed [26]. Due to the relatively sparse literature to assess the efficiency/effectiveness of mouthwashes (chemical methods) to fight and/or control of halitosis, premise of this work was an in vivo crossover, controlled trial comparing chemical methods for evaluation of volatile sulfur compounds H2S and CH3SH against halitosis of oral origin. For positive control was chosen chlorhexidine to be considered the gold standard as an antimicrobial agent and present some evidence of its effectiveness in breath control despite its limited time of effectiveness in studies with halitosis [25-27]. Essential oils were also selected for their nominations for daily use and possibility to compare their versions with and without alcohol, in addition to its known masking breath effect [22-26].
Figure 1
Figure 1
Mouthrinses bottles relabeled and on the original covers. Graduated 15 mL-measuring cups with their respective product identification label at the bottom (externally).
Figure 2
Objectives
The primary objective of this study was to evaluate the overthe-
counter mouthrinses effectiveness in reducing oral breath and
measure how long the effect was lasting, compared to a control with
active compound. As specific objectives we sought to evaluate the
efficacy of:
1. Chlorhexidine digluconate (0.12%) - bis-biguanide (with
alcohol - control);
2. Chlorhexidine digluconate (0.12%) - bis-biguanide (alcohol
free);
3. Essential oils (thymol, menthol, eucalyptol methyl
salicylate) with alcohol and zinc chloride;
4. Essential oils (thymol, menthol, methyl salicylate and
Eucalyptol) alcohol free.
Material and Methods
This trial consists of a randomized, crossover clinical trial with
4 groups and 4 experimental periods, single-center and masking of
patients, the examiner and analysis. All subjects invited to participate
were well informed of the study protocol and objectives, given and
signed their written consent before participation. The project was
approved by the Research Ethics Committee of the RibeiraoPreto Dental
School – (FORP – USP), under number CAAE 02122812.8.0000.5419
from Plataforma Brasil – Brazilian Ministry of Health, according to
declaration of Helsinki (2008). After OralChroma™ calibration [28],
volunteers who were in search of diagnosis and treatment for bad
breath or by invitation of researchers for the study were pre-screened
with the equipment. The randomization was done with 4 sequences of
usage order and the sequence 3 had 6 volunteers instead of 5 [29]. The
sample size was defined according to our previous study [30] being
considered sufficient n=20. Complete medical and dental history is
essential to eliminate confounding effect. The primary focus of the
medical history was on drugs and systemic diseases. Oral history and
a specific questionnaire related to halitosis was used, according to the
consensus of an international workshop and described by Seeman et
al. [31] in 2014 about halitosis management. For inclusion criteria in
the study, the volunteers had to meet the following requirements to
clinical examination [32-33].
1. Presence of at least 20 natural teeth;
2. Good oral hygiene;
3. Absence of periodontal disease, xerostomia, or any chronic
inflammatory process;
4. Patients with intraoral halitosis cause (VSC above 112ppb
for H2S or 26ppb for CH3SH - detected by OralChromaTM).
5. Were excluded smokers, pregnant or lactating volunteers,
patients with systemic diseases (liver, kidney, and diabetes),
pharyngeal or tonsillar infection, upper or lower respiratory tract
inflammation, patients with dentures, fixed prostheses clinically
unsatisfactory, dental caries, lesions on the oral mucosa, those using
drugs regularly or who had undergone treatment with antibiotics
for less than three months. Therefore was avoided the confounding
effects, namely it was prevented from a third interference factor
between exposure and outcome.
The tests were conducted with undergraduate and graduate
students from the campus, staff at the faculty from RibeirãoPreto
Dental School, USP. All 21 participants were within the inclusion
criteria and had healthy conditions of the mouth, without
spontaneous gingival bleeding, absence of periodontal disease (or
probing depth more than 3 mm), but some had dental supra and
subgingival calculus less than 3 mm depth. Dental prophylaxis was
performed in all volunteers prior to the study to maintain periodontal
health status. After prophylaxis was provided to the patients an oral
hygiene kit for their maintenance of hygiene during the period of
study. In the week before the start of the study, participants received
instructions for oral hygiene and dental brush set (Toothbrush Oral-B
Pro Clinical Protection Flex® soft - Procter & Gamble) and toothpaste
(Colgate Toothpaste Maximum Anticaries Protection) provided by
the researcher, so as not to make use of any kind of mouthwash, since
the week before the first intervention and to remain unused for the
entire study period. The elected toothpaste did not contain antiseptic
active ingredients other than sodium fluoride. The flossing was not
restricted. This period led to the standardization of pre-clinical period,
free of possible mouth rinse waste. Before starting the experiments,
the volunteers were instructed to remain for 12 hrs without using
any type of oral hygiene and were asked to avoid eating foods which
decomposition could produce strong odor (such as garlic, onion, egg
and cabbage) and the intake of alcoholic beverages in order to register
the initial levels of VSCs in the morning of the appointment [34].
It was evaluated the efficacy on reduction of VSC, using the mouth
rinses identified by codes at (Table 1) and (Figure 1):
During the pre-trial period all participants had to follow the
instructions below [34]:
• Avoid the intake of food and liquids (except water).
However, they were allowed to have breakfast two hours before the
evaluation period.
• Refrain from any oral hygiene procedures.
• Avoid the use of chewing gum, mints, and candy or
breath fresheners. In this crossover study, each of the 21 subjects
were randomly allocated into a sequence according to a random of
numbers (generated by the software R version 3.2.0 Windows®), so
that the first volunteer received the treatment 3, the second received
treatment 1 and so on, to one of the 4 sequences for the products (see
CONSORT Flow Diagram, Figure 2).
The portable gas chromatograph (OralChromaTM, FIS Inc., Itami,
Japan), was used to measure the concentration of H2S, CH3SH,
both intraoral sources. The sample collection occurred by use of a
disposable syringe (fully plastic 1 mL) purchased with the unit, which
was inserted into the mouth of volunteers. Subjects closed their
mouth and “mouth washed” the air for 30 seconds prior to sample
collection. The volume of 1 mL mouth air was then injected into
the measuring device. After 8 min the process was completed and
the concentration of the three gases were displayed in ng/mL or 10
ppbv (nmol/mol) according to the corrections on the chromatogram
made by tangerman and colleagues in 2008 [28]. The participants
were submitted to analysis by portable gas chromatography
for identification of hydrogen sulfide and methyl mercaptan
(methanethiol). On the morning of the experiment, the volunteers
were allowed to have breakfast without being made any kind of oral
hygiene and should not use any cosmetic that would release odor/
scent [35]. Each individual used 15 mL of mouth rinses A or B and
20 mL of mouth rinses C or D at the rate of one minute according to
the manufacturers recommendations only once during the day of the
assay. Therefore, the breath of each volunteer was examined in the
following intervals [36-38]:
• time 0 = before using the product (initial data/baseline);
• time 1 = 1 hours after rinsing;
• time 2 = 2 hours after rinsing;
• time 3 = 3 hours after rinsing;
After obtaining the data, the volunteers were instructed to sanitize
the mouth, making use of toothbrush and dentifrice only supplied
by researchers for a period of over one week (7 days) (washout) to
avoid interference with the results of next week (carry over) based
on similar studies with CHX [34,39-45]. After this period, the next
interventions occurred having their washout intervals until all the
products were tested by all individuals at the end of the experiment.
The material collected for analysis in chromatograph was injected
directly into the device via the specific aperture (hole feeder). The
data recorded by OralChromaTM were collected and tabulated in an
Excel spreadsheet and in accordance with the codes marked on the
bottles and submitted to the following statistical tests described:
It was initially performed an exploratory analysis of data through
graphs and central position and dispersion measurements (mean,
standard deviation, median, minimum and maximum values). Mean
comparisons of variables: H2S and CH3SH were made by linear
regression mixed models [46]. When using this model, it is necessary
that their residues have a normal distribution with zero mean and
constant variance. The model fit was done by PROC MIXED of SAS®
9.2 software. It was found that significant differences were noted only
when p<0.05 (5% significance level).
Figure 3
Figure 3
Line graph illustrates the relationship between concentrations (ppb) and time (hours), for each rinse. The dotted horizontal line represents the minimum detectable value to the human sense of smell, at 112ppb for H2S and 26ppb for CH3SH.
Table 1
Results and Discussion
This study was designed as a crossover clinical trial, since its
main advantage is to eliminate the existing large variation among
individuals in response to a treatment, given that all treatments
are assigned to all individuals. Thus, each patient served as his own
control, increasing the study efficiency from a statistical point of
view, given the necessity of a smaller number of participants and such
drawing has been widely used [20,33,35,47-53]. For this to happen,
each treatment should be reversible, following a similar course during
all periods and there should be no residual effect transfers from one
treatment to another. In addition, individuals must be willing to
receive all treatment regimens and each treatment period should be
of sufficient duration to provide convincing data. This can make a
long-term project an impractical crossover [54]. From the 106 prescreened
volunteers, 81 did not fit the inclusion criteria, by smoking
habits, systemic diseases or antibiotic use within the previous two
weeks. From the 25 pre-selected to the study, 23 reported unaware
of being carriers of halitosis. Only 1 patient reported knowledge on
having halitosis by aversive social behavior from colleagues. One
patient reported feeling bad taste and presence of caseum in the
throat with some frequency. Four volunteers dropped out from the
trial in the preclinical period (after completion of dental prophylaxis
and before the start of the tests). Twenty-one volunteers of both
genders were selected, aged between 18 and 50 years with good
general health. It has been shown that the confidence intervals better
inform readers about the possibility of inadequate sample size than
post hoc power calculations [55]. After exploratory data analysis,
it was possible to construct a summary table of the measurements.
With these values it was possible to construct a graph that allows
display the gases behavior for each rinse in each time, according to
(Figure 3). When people are allocated into sequences some individual
characteristics such as age or sex (i.e.) can bring to the sequence some
significantly differences. Groups containing older people may have
the biggest breath values. This can occur when the randomization
process for allocating the sequences volunteers is not done properly.
The comparison of sequences is important to infer if a higher number
of people with more elevated levels of breath were allocated to one or
another sentence. For Both H2S and CH3SH, the values did not differ
among the sequences. It can be inferred, then, that the distribution of
volunteers in these sequences was valid and therefore it did not cause
interference into the results, which can be seen on (Table 2). However,
there were significant differences among the products compared with
each other, regardless of time, both H2S and for CH3SH (Table 3).
Comparison of baseline values of H2S and CH3SH for each
product
When mouthrinses baselines were compared, no differences were
noted between them. This indicates a washout period sufficient to
prevent residual effect (carry-over) for both gases (H2S and CH3SH)
studied - as shown in Table 3. According to Figure 3, the baseline
averages of hydrogen sulfide for all groups were above 400ppb for
H2S, indicating strong halitosis values, and the CH3SH means were
from 150ppb, which are also considered high values (threshold
26ppb), and 5 times larger than the gas threshold perception. The
latter compound has more penetrating odor than hydrogen sulfide.
Thus, even in lower concentrations their odor can more easily overlap
the others [4]. For tangerman and Winkel (2007), the odor index of
Methyl Mercaptan (MM) is about three times greater than the H2S,
MM recognition threshold is about 1/30 of the threshold of H2S and
objection capacity about 1/8 of the H2S. These figures show that MM
has a much higher potential than the H2S odor, indicating discomfort
at much lower concentrations than H2S. These results suggest that
MM is the predominant causal factor in oral halitosis, which is in
accordance with results of other researchers [56,57]. During the first
hour, comparisons were made among mouth rinses. The mean values
of H2S for chlorhexidine with alcohol, chlorhexidine alcohol-free and
essential oils with alcohol/zinc chloride were significantly lower than
the averages for those who used essential oils alcohol-free. Essential
oils containing alcohol/zinc chloride had the best performance,
followed by chlorhexidine with alcohol and then chlorhexidine
alcohol-free. Clinically there was a lower level from baseline for these
three products. The alcohol effect in this case can be of fundamental
importance, because zinc chloride without alcohol could not be
better than distilled water in a recent study by Kim and colleagues,
published [58]. The disadvantage of this product was the intense
burning sensation and tearing of the volunteers who resisted with
sacrifice to rinse 20 mL of the product for 30 seconds. During the
second hour, the average H2S values were almost identical of those
from the first hour, where the average values of H2S for chlorhexidine
with alcohol, chlorhexidine alcohol-free and the essential oils with
alcohol/zinc chloride were significantly lower than the averages for
those who used essential oils alcohol-free. Chlorhexidine with alcohol
had the best performance, followed by essential oils with alcohol/zinc
chloride and after the chlorhexidine alcohol-free. At this moment,
the effect was similar to the previous, but the CHXw/a had the best
performance, perhaps for the continuity of its antimicrobial action,
reaching an average below the olfactory threshold (102ppb), namely,
the bad breath already was (by average) imperceptible in the second
hour. Next were the essential oils with alcohol and zinc chloride and
chlorhexidine alcohol-free, in that order, corroborating other results
of studies on the effects of neutralization of compounds or antibacterial
activity of these agents [20,59]. During the third hour, the mean
behavior was similar to the first and second hours. The mean values
of H2S to chlorhexidine with alcohol, chlorhexidine without alcohol
and essential oils with alcohol/zinc chloride were significantly lower
than the averages for those who used essential oils without alcohol.
Chlorhexidine with alcohol had the best performance, followed by
essential oils with alcohol/zinc chloride and after the chlorhexidine
without alcohol. This can be explained by the inherent antimicrobial
activity of chlorhexidine, regardless of the alcohol component,
against gram-negative anaerobic micro-organisms H2S producer
[26,60,34]. Listerine Total Care® reached the lowest average (about
80ppb) being below the threshold of perception. In its composition
with alcohol solvent in addition to the essential oils, has a penetration
enhancer factor, both as bacterial and epithelial cells, and, more, in its
composition there is zinc chloride which is readily soluble in ethanol
and water, and for being metal ions can oxidize the sulfur compound
and turn it into a non-volatile product [58]. Essential oils are regarded
as breath masking, in other words, with its high odorous power may
overlap the odor of the tested compounds [26].
Behavior of each mouth rinse over the 3 hour
Chlorhexidine with alcohol (A): There was a significant reduction
in average throughout the entire time when compared to initial
values. But comparing the first, second and third hours the reduction
was not significant among them. There was a significant reduction
in VSC levels throughout the time when compared to initial ones.
But between the first, second and third hours the reduction was not
significant among them, or, there was a considerable drop in the first
hour and levels were maintained throughout the experimental period.
Considered as a positive control in this study and considered as the
gold standard of antiplaque agent and until then for halitosis [61], this
product confirmed its validity. The big problems of chlorhexidine are
the side effects of dental pigmentation, taste alteration that preclude
its daily use. The purpose of this study was to verify the existence of
an alternative as or more effective in controlling the breath as this
product. This way will be considered the one with best properties to
control the volatile sulfur compounds of intraoral origin and fewer
adverse effects associated with its continued use. The search for a
superior product with possibility of continued use is based on the
fact that high concentrations of volatile sulfur compounds should be
addressed locally (oral cavity), since both gases (H2S and CH3SH) are
produced endogenously and contribute to human homeostasis and
are not only toxic or unpleasant product of bacterial metabolism.
The halitosis diagnosis usually takes some time to be determined
in patients seeking treatment due to several factors that may be
associated and are causing repulsion of people. Products resulting
from tissue necrosis or systemic factors were excluded from this study
so that this does not interfere with the behavior of the studied gases,
since such problems require other approaches [62,63]. Even healthy
patients and apparently without oral problems may be suffering
from halitosis by protein degradation from the tongue coating or
present in the crevicular fluid. Studies have shown an association
of H2S to bacterial sub-products on the tongue surface and the
CH3SH formation in periodontal conditions of disease [64,65]. The
oral hygiene by mechanical removal of tongue biofilm is not always
possible within the deepest niches and only mouth rinses would be
able to penetrate deeper and have a longer lasting action.
Chlorhexidine alcohol-free (B): There was a significant reduction
in average throughout the whole time when compared to initial values.
But compared to the first, second and third hours the reduction was
not significant among them. With a similar action to the version with
alcohol, its performance over time was not statistically different from
the control, although it was a bit lower. It could be a valid option for
patients with restrictions on the use of alcohol, unless they have high
levels of sulfides (severe halitosis) and require antimicrobial control
for a short period, and post-operative treatments or adequacy of oral
environment, usually two weeks [82]. Clinically, patients finished the
test with weak bad breath, noticeable only less than 10 cm away.
Essential oils with alcohol and zinc chloride (C): There was a
significant reduction in average throughout the entire time when
compared to initial values. But compared to the first, second and
third hours the reduction was not significant among them. With
better performance among other products to control the H2S levels,
was effective within the first hour with values under the olfactory
threshold and seventh magnitude reductions, in other words, after one
hour the average values were 7 times smaller than the initial and at the
end of three hours. It was inferior only to the control, consequently a
valid alternative for severe intraoral halitosis for unrestricted alcohol
at longer periods than chlorhexidine.
Essential oils alcohol-free (D): There was a significant reduction
in average throughout the entire time when compared to initial values.
Negative values represent the difference between the mean of the
breath with the increase over time, demonstrating that mouth rinse
was not effective in reducing breath. From first to third there was an
increase in values but not significant. The lack of efficacy throughout
the study period (although being by the manufacturer as a call from
the undesirable effects of alcohol) the product cannot be used in order
to reduce the breath volatile sulfur compounds. Worse than that, led
to an increase, without significance, baseline levels. Additional studies
should be conducted to evaluate its effects on other compounds (such
as volatile organic, for example) of putrefactive origin.
CH3SH analysis
Considering the different values between the CH3SH levels among
mouth rinses regardless of the time (Table 3), paired comparisons
were made, noting that the mean values of CH3SH for essential oils
with alcohol/zinc chloride differed from:
• chlorhexidine with alcohol
• chlorhexidine alcohol-free
So we proceeded to perform the analyses among mouthrinses at
each time and for each one over time.
Whereas there were no differences between baselines among all
mouthrinses, it was observed that:
Analysis of time:
First hour: During the first hour, comparisons were made
between mouth rinses. The mean values of CH3SH for essential oils
with alcohol/zinc chloride were significantly lower than the averages
for those who used chlorhexidine with alcohol and chlorhexidine
without alcohol. Essential oils with alcohol/zinc chloride had the
best performance, followed by a version without alcohol. Meanwhile,
the versions of chlorhexidine had no effect on this odorivector. The
Listerine® containing alcohol and zinc chloride was the most effective
in reducing this compound followed by its alcohol-free version. The
biguanide had no influence on this compound, in agreement with the
predilection of periodontists by essential oils to combat periodontal
bacteria [66]. It seems to exist one direct relationship between the
essential oil activity and methanethiol generation. It must also be
explored in future studies, the possibility of alcohol penetration
and zinc chloride participation as this gas oxidant. Another
factor to consider is the possibility to have occurred methanethiol
demethylation into hydrogen sulfide using essential oils without
alcohol.
Second hour: During the second hour, CH3SH the mean values
did not differ for each of the mouth rinses.
Third hour: During the third hour, the mean values of CH3SH
for essential oils with alcohol/zinc chloride were significantly lower
than the averages for the essential oils without alcohol. Essential oils
with alcohol/zinc chloride had the best performance. There was no
difference among the other mouthrinses.
Behavior of each mouth rinse over the third hour:
Chlorhexidine with alcohol (A): It was not able to reduce the
mean values compared to baseline or to other times.
Chlorhexidine alcohol-free (B): It was not able to reduce
the mean values compared to baseline or to other times. It can be
concluded that the presence of alcohol was unable to influence the
performance of this ingredient on methanethiol.
Essential oils with alcohol and zinc chloride (C): It was the
only mouth rinse that declined in the other three times. There was
a significant reduction in average throughout the entire time when
compared to initial values. Among the first, second and third time,
there were no significant differences. It was the only mouth rinse that
showed efficacy at all times compared to baseline and the effect lasted
for up to 3 hrs. Analysis of the chemical reaction between alcohol,
zinc chloride, the VSC and with association of proteolytic bacteria are
required to elucidate these mechanisms.
Essential oils alcohol-free (D): It was not able to reduce the mean
values compared to baseline or to other times. Compared to baseline
values increased at the end of the third hour, however insignificant
In summary, the mouth rinse based on essential oils with alcohol and
zinc chloride was the only one capable of significantly reducing both
values of H2S and CH3SH at the first hour and its effect lasted for
up to three hours below the baseline values (significantly). Clinically
appeared as weak values or imperceptible to the human sense of smell
after the 1st, 2nd and 3rd hrs. Just 10 cm away could notice a faint breath,
when it was possible. For H2S, the mouth rinse with chlorhexidine with
and without alcohol also obtained satisfactory results for reducing the
breath. Only the product based on essential oils without addition of
alcohol was not able to reduce the breath and enabled to increase the
H2S values initially recorded. For CH3SH, none mouth rinse was able
to reduce the breath from the initial values than the one based on
essential oils with alcohol and zinc chloride in the formulation. This
information can be best seen in the graphs a) and b) of (Figure 3).
Products with alcohol in the composition achieved the best results
for reducing H2S but for CH3SH chlorhexidine alcohol was not able
to significantly reduce of breath, whereas compound with alcohol
and zinc chloride (essential oils) was unsurpassed. The alcohol-free
mouth rinses presented the worst results, and essential oils being able
to increase the initial values for both gases after 3 hrs.
Table 2
Table 3
Conclusions
At the end of the clinical phase, with the agreement and abidance
of 21 volunteers throughout the study, in light of the results and
within the limitations explored in the discussion of the work, we may
conclude that:
• The mouth rinse based on essential oils, alcohol and zinc
chloride was the only one able to efficiently reduce the breath by
controlling the volatile sulfur compounds (odorivectors) from intraoral
source for up to three hours after single use;
• The elimination of alcohol and the absence of zinc chloride
in the new Listerine "zero" version had a negative effect on the efficacy
of the product against halitosis of oral origin;
• The control product had the second best performance, being
effective only against the odorivectors sulfur hydrates. The alcoholfree
version can also be an option in cases where alcohol prohibition
is imperative. The elimination of alcohol does not significantly alter
the performance of chlorhexidine.
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