Walsh, Laurence J.

University of Queensland eSpace

6 0 -  D e n t a l  P r a c t i c e J u l y / A u g u s t  2 0 0 6
V olatile sulfur compounds (such ashydrogen sulfide, methyl mer-captan, dimethyl sulphide) and
certain acids and amines (propionic and
acetic acids, cadaverine and putrescine)
are occasional ingredients in the gas mix-
ture which is exhaled air. These
substances arise primarily from putrefac-
tion of the sulphur-containing amino
acids within large proteins through the
action of host and bacterial proteases,
with Gram-negative anaerobes featuring
in the latter. Many practitioners will recall
the unique sulphurous odour of tissue
fragments removed from necrotic teeth on
a barbed broach or endodontic file, since
the same bacterial putrefaction processes
occur within the root canal space of non-
vital teeth.
Although nocturnal salivary hypofunc-
tion; thick deposits of supra and
sub-gingival dental plaque; and long-
standing untreated periodontitis are
common contributors to halitosis, recently
the emphasis has shifted to accumulations
of bacterial plaque and debris on the pos-
terior aspects of the tongue. Most studies
link one or more of these oral causes to
nearly 90% of cases of halitosis, with the
remainder being systemic in nature (e.g.
postnasal drip and ENT disease, liver cir-
rhosis, and untreated diabetes mellitus).
Find it
Salivary dysfunction can be screened for
readily using the Saliva Check Buffer kit
(GC Corporation), while the maturity of
plaque deposits in the mouth can be
rapidly assessed using the 2-tone plaque
disclosing system in the GC Plaque Check
+ pH kit. This stains mature plaque blue
and thin, immature plaque red. A more
high technology approach is the Morita
Penscope (Penviewer), which in addition
to a conventional white LED-illuminated
miniature intraoral camera has an addi-
tional camera with 4 visible violet/blue
short wavelength LEDs and a filter on the
corresponding CMOS sensor which
shows mature plaque deposits in red
because of their fluorescence properties.
Measure it
Sulphide monitors have been used widely
for halitosis assessment. Interscan’s
Halimeter®, which was the first unit specif-
ically designed to measure VSC in clinical
dental practice, shows an aggregate of all
VSCs (in parts per billion, ppb) rather than
a breakdown of the main components. It
has a low sensitivity for methyl mercaptan
(which has been linked to periodontitis) but
high sensitivity for hydrogen sulphide. The
Halimeter does however allow a rather
useful recording of the total VSC level to be
obtained in the form of a chart recording
which is appropriately named a Haligram®.
Feeling somewhat behind the scene, the
author admits to having in his possession a
stationary industrial gas measurement
system (Draeger) which measures
upwards of 200 ppb for hydrogen sul-
phide, but without the digital readouts or
data recording of the OralChroma or
Halimeter. It employs a chemical reaction
which gives a visible reaction product
rather than an electronic sensor.
The latest technology for assessing oral
malodour is the portable gas chromatograph.
Seasoned airline travelers will be familiar
with the use of these devices at airline secu-
rity checkpoints for detecting explosives
and illicit drugs. The same technology has
now recently become available for dental
practice in the form of the OralChroma™, a
portable gas chromatograph which mea-
sures in a sample of mouth air the levels of
three key VSCs, namely hydrogen sulfide,
methyl mercaptan, and dimethyl sulfide.
The role of these VSCs in oral malodour
has been shown in many studies, but pre-
vious gas chromatography equipment was
so bulky that its use was confined to
research, where it has appropriately served
for many years as the “gold standard”.
OralChroma data can be downloaded to a
personal computer via a serial or USB
cable, and OralChroma Data Manager soft-
ware will graphically display the sensor
responses on a computer screen, and save
the data. An interesting feature is that Data
Manager software allows individual values
for the “halitosis perception threshold” to be
set in the range of 0 to 1,000 for each gas
component (most individuals will notice
objectional mouth odour at VSC levels
above 75 ppb). The manufacturers suggest
that in cases where the causes are not
apparent, the differential assessment of the
three components can be worthwhile, for
On the nose - new diagnostic and 
treatment approaches for oral malodour
BY PROFESSOR LAURENCE J. WALSH
THE CUTTING EDGE
Figure 1. The Morita Penviewer (Penscope). Panel A, the two intra-oral cameras 
sitting on the unit. Panel B, the differing LED illuminators. The plaque detection
handpiece is in the foreground.
6 2 -  D e n t a l  P r a c t i c e J u l y / A u g u s t  2 0 0 6
example, unusually high levels of methyl
mercaptan have been linked to untreated
periodontitis. This of course cannot substi-
tute for a thorough history and careful
clinical examination (including periodontal
probing!). Nevertheless, measuring each
major component also allows cases of
pseudo-halitosis (imaginary halitosis) to be
identified and formally excluded, so that the
patient can be referred for appropriate psy-
chological or psychiatric care if indicated.
Treat it
1. Tongue cleaners - The range of treat-
ments and remedies currently available for
halitosis continues to expand, with tongue
cleaners now included on a number of
“mainstream” toothbrushes. These are
used to clean the dorsal surface of the
tongue thoroughly, specifically to remove
the protease-producing anaerobic bacteria
that produce VSCs, along with other bac-
teria, epithelial squames and foreign
matter. This is not as simple a task as it first
appears, since the dorsum of the tongue is
irregular and its fissures are ideal low-
oxygen ecological niches for anaerobic
bacteria, which are protected there from
the antimicrobial systems present in saliva.
2. Replacement therapy with Strepto-
coccus salivarius (BLIS K12) - The term
BLIS is an abbreviation for bacteriocin-
like inhibitory substances, molecules
which are produced by many bacteria as a
means for establishing and maintaining
microbial microenvironments. S. sali-
varius is the only probiotic that can live in
high numbers on the dorsal surface of the
tongue. Moreover, laboratory testing has
shown that a naturally occurring strain of
S. salivarius (K12) suppresses the growth
of Gram negative anaerobic (black-pig-
mented) bacteria which have been
implicated in halitosis.  Healthy individ-
uals with low levels of VSCs have a high
proportion of S. salivarius on the dorsum
of the tongue (up to 40% of the cultivable
flora), whereas sufferers of chronic hali-
tosis have very low levels.
The concept of using BLIS K12 as a pro-
biotic agent was developed by Professor
John Tagg, a microbiologist at the Univer-
sity of Otago. Based on his work, there are
now a range of BLIS K12 products, which
are also known as KForce™. Treatment for
halitosis involves using a chlorhexidine pre-
rinse to alter the oral microbial ecology
before introducing the S. salivarius (via
lozenges). A recent placebo-controlled clin-
ical study has shown that using BLIS K12
used in chronic halitosis sufferers resulted
in the majority of subjects (85%) achieving
a significant reduction in VSCs and in bac-
terial proteolytic (BANA) activity.
Of interest, the same probiotic approach
may also have value in altering the
ecology of dental plaque to prevent dental
caries, given that a number of oral bacteria
are known to produce BLIS activity
against Streptococcus mutans. Clinical
approaches that are under investigation in
this regard by the group in Otago include
the regular oral administration of the puri-
fied BLIS molecules, and the genetic
modification of existing plaque bacteria
such that they produce significant quanti-
ties of the anti-mutans BLIS in situ.
3. Biocides - Antimicrobial agents which
have been used successfully include
chlorhexidine, Triclosan products such as
Colgate Total™, essential oils (Listerine™),
and cetylpyridinium chloride (BreathRx™).
4. Zinc ions - Topical therapies can
deliver bio-available zinc ions which
bind to protein receptors on the surface of
oral bacteria, preventing the proteins
binding and being metabolized. Such
products are generally formulated with
stabilized chlorine dioxide (e.g. Tri-
Oral™ rinse, Oxygene™).
5. Oxidizing mouthrinses and sprays -
These agents convert VSCs chemically
into non-odourous harmless compounds
and exert actions against the strictly
anaerobic bacteria which lack catalase
and thus find oxygen based molecules
toxic to their normal metabolism. Exam-
ples of oxidizing products include
sodium chlorite and “stabilized” chlorine
dioxide (Therabreath™, CloSYSII®,
ProFresh™, DioxiCare®), other oxychlorine
compounds, hydrogen peroxide mouthrinses
(Colgate Peroxyl™, Listerine Whitening™),
and freshly ozonated water. Of these, recent
interest has focused on the latter, since water
can be ozonated on demand at the chairside
for use in mouthrinsing. Ozonated water has
been shown by the Belfast research group of
Professor Ed Lynch (inventor of the Healo-
zone) to oxidize the sulphur-containing
amino acids cysteine and methionine, which
serve as chemical precursors for VSCs, into
their corresponding primary oxidation prod-
ucts cystine and methionine sulphoxide.
Recommended reading
www.verifresh.com/JCDP_Bad_Breath_Info.pdf
www.verifresh.com/BDA_Bad_Breath_Info.pdf
www.verifresh.com/ADA_%20Bad_Breath_Info.pdf
• Kazor CE, et al. Diversity of bacterial populations of the
tongue dorsa of patients with halitosis and healthy patients.
Journal of Clinical Microbiology 2003, 41(2): 558-563.
• Tagg, JR et al. Application of inhibitor typing in a study of
the transmission and retention in the human mouth of the bac-
terium Streptococcus salivarius. Archives of Oral Biology
1983; 28: 911-915.
• Burton J, et al. The rationale and potential for the reduction
of oral malodour using Streptococcus salivarius probiotics.
Oral Diseases 2005; 11(s1): 29-31.
• James SM, Tagg JR. The prevention of dental caries by
BLIS-mediated inhibition of mutans streptococci. New Zealand
Dental Journal 1991; 87(389):80-3. 
• Tagg JR, Dierksen KP. Bacterial replacement therapy:
adapting ‘germ warfare’ to infection prevention. Trends in
Biotechnology 2003; 21(5):217-23.
Professor Laurence J. Walsh is the tech-
nology editor of Australasian Dental
Practice magazine. He is also a noted
commentator on and user of new technolo-
gies and is the Head of The University of
Queensland School of Dentistry.
THE CUTTING EDGE
Figure 2. A screen capture from OralChroma software. Num-
erical data for each of the three VSCs is presented separately.
Figure 3. BLIS K12 
preparation delivered 
as lozenges.
CPD POINTS AVAILABLE
Continuing Education credits are 
available on this article for subscribers
by answering the questionnaire at
www.dentalpractice.com.au


On the nose - new diagnostic and treatment approaches for oral malodour

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On the nose - new diagnostic and treatment approaches for oral malodour

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