The Matt & Jo Show

Media item: radio segment

Programme: the Matt & Jo show, Melbourne commercial radio

Date broadcast: 20 April 2012

This page records the media item. The audio is the property of the broadcaster and is not reproduced here.

No individual's dental treatment is described here, and section 133 of the National Law prohibits testimonials about clinical care in advertising a regulated health service.

What follows is general information on the subject people ask about most and admit to least: bad breath. The practice's own page on it is at Bad Breath, and the articles are What causes bad breath and how can I fix it? and How do I get rid of my bad breath?!

Where it actually comes from

Most persistent bad breath originates in the mouth, not the stomach — and the number in general circulation is not the number the research published.

Quirynen and colleagues, in the Journal of Clinical Periodontology in 2009, examined 2,000 consecutive patients attending a multidisciplinary bad-breath clinic in Leuven, Belgium, most of whom came without referral and had been complaining for a mean of seven years. An oral cause was found in 76 per cent — tongue coating in 43 per cent, gingivitis or periodontitis in 11 per cent, and both together in 18 per cent. Non-oral ear, nose and throat causes accounted for 4 per cent, and 16 per cent had no detectable odour at all.

The widely quoted "85 to 90 per cent" is that same 76 per cent re-based to exclude the people with no detectable odour, and the restriction is almost always dropped when the figure is passed on; the FDI World Dental Federation's 2025 advice sheet gives "85-90%" with no citation at all. The population matters too: these were self-selected attenders at a specialist clinic, not a general practice.

The mechanism is specific: bacteria break down proteins and produce volatile sulphur compounds — hydrogen sulphide, methyl mercaptan, dimethyl sulphide. Those are the smell. How do I make sure I never have bad breath (halitosis)? goes further into it.

The largest single oral source is coating on the back of the tongue — 43 per cent of cases on its own in the Leuven series. The posterior dorsum is rough, poorly cleansed, and holds a substantial bacterial load; the ADA puts the whole mouth at "around 700 forms of bacteria", many of them collecting there. Most people never clean it — see Do I need to use a tongue scraper? and Should I use a tongue scraper?

The other oral sources:

• Periodontal disease. Deep pockets are anaerobic and produce exactly these compounds. Persistent bad breath with bleeding gums is gum disease until proven otherwise — see Bleeding Gums, What is gum disease? and Periodontal (gum) disease.
• Dry mouth. Saliva clears and buffers; without it, everything worsens. This is why morning breath exists — saliva flow falls overnight in everybody. See My mouth is always dry and My mouth always feels dry! What can I do?
• Untreated decay, food traps, and failing restorations — The stages of dental decay and Tooth Fillings.
• Poorly cleaned dentures, particularly worn overnight — 5 things you should know about your new dentures.
• Tonsil stones (tonsilloliths) — small calcified plugs in the tonsillar crypts. Genuinely malodorous, harmless, and frequently missed.

The non-oral causes, which are the minority

Worth knowing, because when they apply, no amount of brushing helps. The ADA is the only Australian source that says so outright to consumers: bad breath "can actually be caused by other areas of the body including the lungs and the nose".

• Sinus and post-nasal drip, chronic sinusitis, tonsillitis — the largest of the non-oral group, and often linked to mouth breathing
• Reflux, in some cases — which also shows up as dental erosion
• Diabetes, where poorly controlled ketosis produces a distinctive sweet, acetone-like odour — Diabetes and oral health
• Kidney or liver disease, which produce characteristic odours and are late signs of serious illness
• Some medications, mostly through dry mouth
• Smoking, which both smells and causes gum disease — see also the effects of vaping on your oral health
• Diet — garlic, onion, alcohol and some spices are absorbed and exhaled from the lungs. No mouthwash reaches that; it has to be metabolised. Six foods to avoid for healthy teeth

Very rarely, halitosis is the presenting sign of something serious, which is one reason persistent bad breath deserves an examination rather than a supermarket aisle.

What to do, and how weak the evidence behind all of it is

Start with the uncomfortable finding, because it changes how the rest of this reads. Cochrane's review Interventions for managing halitosis (CD012213, 2019) pooled 44 trials and 1,809 participants across eight categories — tongue cleaning, chewing gums, systemic deodorising agents, topical gels, toothpastes, mouthrinses, tablets and combinations. Only three of the 44 trials were at low risk of bias, most followed up for one to four weeks, and the conclusion was blunt: "We do not have enough evidence to say which intervention works better to control bad breath."

So the order below follows what treats an identified cause — not proven effect, because nothing here has one.

1. Get the gum disease treated. If pockets are deep, no amount of home care will resolve the smell, and this is the only item that treats a diagnosed disease rather than a symptom. It needs a practitioner — see Dental Cleans and Hygienists, When do you need deeper cleaning? and, where the disease is advanced, a registered specialist periodontist (Specialist Periodontists).

2. Clean between your teeth, daily. A toothbrush reaches roughly three of the five surfaces of a tooth. The ADA's instruction does not rank the tools: "clean between your teeth daily with floss or interdental brushes", and no independent source we hold establishes that either is better. Interdental brushes are usually easier where the spaces admit them; floss suits tight contacts; the best one is the one you actually use. See Is flossing really that important? and What is the ideal daily routine for oral hygiene?

3. Clean your tongue — but know what it does and does not do. This is where this page has to correct itself. Tongue cleaning is widely promoted as the fix for bad breath, and the Australian Dental Association's own consumer site says it is not: "a review of the scientific evidence in 2019 found no evidence that cleaning your tongue... were effective for managing the cause of halitosis". Cochrane's measurement of mechanical tongue cleaning against none is -0.20 (95% CI -0.34 to -0.07), from 2 trials and 46 participants, very low-certainty evidence. Forty-six people.

The ADA page contradicts itself here, and the contradiction is worth seeing rather than resolving. Its key-messages box says "Cleaning your tongue can help to reduce bad breath"; the body of the same page says the 2019 review found no evidence; and its summary line splits the difference — cleaning the tongue "can reduce the bacterial load on the tongue, but the impact of this reduction has not been proven yet". The body text is the defensible reading.

So clean your tongue because it is reasonable and harmless, not because it is proven. The ADA's technique advice is specific: be gentle, because "the tongue surface is delicate and sensitive"; "start gently at the back of the tongue, pulling or brushing forward and use water to lubricate the process" — and a soft-bristled toothbrush will do, though a scraper can also be used. The 2014 international consensus workshop adds two limits: the dorsum only, not the lateral borders, and not at all in the absence of coating.

4. Deal with dry mouth. Water, sugar-free gum to stimulate flow, saliva substitutes, and reviewing medications with the prescriber — not stopping them. Healthdirect's instruction is to avoid whatever aggravates dryness, explicitly including alcohol-containing mouthwashes, along with cigarettes, e-cigarettes, alcohol, caffeinated drinks and spicy foods. Does chewing sugar-free gum really help prevent cavities?

5. Get untreated decay and failing restorations dealt with.

6. Stop smoking.

7. Clean dentures properly, and take them out overnight unless specifically advised otherwise.

What does not work, or is weaker than advertised

Mouthwash. It masks for twenty minutes to an hour. It does not treat the cause, and an alcohol-based rinse can dry the mouth and make things worse over time — which is healthdirect's position, not a stylistic preference.

On antibacterial rinses, be precise about what has actually been shown. Cochrane CD008676 (2017) found high-quality evidence of a large reduction in plaque from chlorhexidine used alongside brushing — standardised mean difference 1.45 (95% CI 1.00 to 1.90), 12 trials, 950 participants. But on the same high-quality evidence the reduction in gingivitis in mildly inflamed gums "was not considered to be clinically relevant", there was a large increase in extrinsic tooth staining (SMD 1.07, 95% CI 0.80 to 1.34), and no concentration outperformed another. For bad breath specifically, the single trial of a chlorhexidine-and-zinc-acetate rinse gave -0.20 (95% CI -0.58 to 0.18) — the interval crosses zero, so no benefit over placebo was demonstrated. Australian Prescriber's framing is the one to keep: an adjunct to, not a substitute for, regular brushing and flossing, which "should never be the sole means of oral hygiene". See The truth and myths about mouthwashes and Should I be using mouthwash as well as brushing and flossing?

Mints and chewing gum with sugar. Masks the smell, feeds the bacteria, causes decay. Sugar-free gum is genuinely useful — not for the flavour but because it stimulates saliva.

Treating your stomach. Almost never the cause — How can I guarantee I always have fresh breath?

Charcoal anything. No evidence for halitosis, and it abrades enamel — Home whitening and charcoal whitening: does it work? Is it safe?

Oil pulling. No policy statement, guideline or trial on it appears in any independent source we hold — no evidence of benefit, and using it in place of treatment delays diagnosis — Can oil pulling make my mouth healthier and my teeth whiter?

The awkward part: you cannot smell your own breath

This is a real physiological effect — you adapt to your own odour and stop perceiving it. Cupping a hand over your mouth and breathing into it does not work either, because you are still smelling the same air you are adapted to.

Slightly better home tests: lick the inside of your wrist, let it dry for ten seconds, and smell it; or draw dental floss between your back teeth and smell the floss. Neither is reliable.

Ask someone you trust. It is a genuinely kind thing to be told.

And the opposite problem, which is also real

Halitophobia — persistent conviction of having bad breath when no odour is detectable to others, and no cause is found on examination.

It is common enough to matter. In the Leuven series of 2,000 people attending a dedicated bad-breath clinic, 16 per cent had pseudo-halitosis or halitophobia: no objectively detectable malodour at all. That is four times the rate of non-oral disease in the same population, and the authors placed equal weight on identifying it as on identifying disease.

It is recognised, it is distressing, and it does not respond to more mouthwash. Where examination and objective assessment find nothing, the useful next step is a conversation with a GP, not another product. It is closely related to the body-image conditions discussed at Smile for the ultimate selfie.

When to see someone

• Bad breath persisting despite good interdental cleaning for a few weeks — see a dentist. Gum disease is the most likely explanation and it is painless. How often should I go to the dentist?
• With bleeding gums — see a dentist.
• With a persistent blocked nose or post-nasal drip — see a GP.
• With a distinctive sweet or ammonia-like odour, or with any general symptoms — see a GP.
• And the standing rule: any ulcer, white patch, red patch or lump that has not healed in three weeks needs examining. The RACGP sets the threshold at "more than two to three weeks" for any unexplained or non-healing change in the mouth — a persistent ulcer, red patches, lumps or a sore throat — and notes that initial lesions of oral cancer are generally painless. See Oral cancer: signs, risk factors and how your dentist can help.

Related pages: Bad Breath, Bleeding Gums, Specialist Periodontists, General Dentistry, More than healthy teeth, and the rest of the media record.

Common questions

Does cleaning my tongue actually fix bad breath?

Not on the evidence available, and this page used to imply otherwise. The ADA's own consumer site states that "a review of the scientific evidence in 2019 found no evidence that cleaning your tongue... were effective for managing the cause of halitosis", while the key-messages box on the same page says it can help — a contradiction the ADA has not resolved. Cleaning the tongue gently is reasonable and harmless; it is not a proven treatment. Where bad breath persists, pursue a diagnosis — most often gum disease — rather than another product.

Can it actually be measured, or is it just someone's opinion?

It can be measured two ways, and the most important thing to know is that the three available judgements — yours, a trained assessor's and an instrument's — do not agree with each other. A population study of 419 adults in Bern, Switzerland used a standardised questionnaire, two independent organoleptic assessments (a calibrated judge scoring the odour on a 0 to 5 scale) and measurement of volatile sulphur compounds. The results: 32 per cent said they sometimes or often had bad breath; 48 people — 11.5 per cent — scored grade 3 or higher on the organoleptic scale; and 117 people, 28 per cent, had VSC readings of 75 parts per billion or more. The authors' own conclusion is the useful sentence: "only a weak correlation between self-reported halitosis and either organoleptic or VSC measurements could be detected." Note that the two objective measures also disagreed with each other — 11.5 against 28 per cent — because each depends on the instrument and the cut-off chosen, so neither figure should be repeated as "the prevalence of bad breath", and this was one Swiss city with 419 people in 2009. Two practical consequences. First, self-diagnosis is the least reliable of the three, which cuts both ways: people who are sure they have it often do not, and people who have it often do not know. Second, an assessment by a clinician is worth having, and where a dedicated clinic measures both, the severity is usually modest — in the Leuven series most patients scored below 3 organoleptically and below 240 parts per billion.

Which of the usual suspects actually shows up when you measure it?

Three, and they held up on both measurement methods in the same general-population sample rather than in a clinic. In the Bern study, tongue coating, the modified periodontal screening index and smoking were all significantly associated with higher organoleptic scores, and tongue coating and smoking were also associated with higher volatile sulphur compound readings. That is a short and unglamorous list: the state of your gums, the coating on your tongue, and whether you smoke. It is also one of the few places where periodontal status is shown associated with measured malodour in an ordinary population rather than among people who presented at a specialist clinic. Nothing about diet, stomachs or particular foods appears in it. See Periodontal (gum) disease and Bleeding Gums.

Is there a gum, tablet, gel or toothpaste that has been shown to work?

Not on the trial evidence, and the detail is worth seeing because these products are sold as though there were. Cochrane's review tested eight categories across 44 trials and 1,809 participants, with only three trials at low risk of bias, and its per-comparison results were these. Chewing gum — 0.6 per cent eucalyptus gum against placebo gum: MD −0.10 (95% CI −0.31 to 0.11), 1 trial, 65 participants, very low certainty. A systemic deodorising agent — 1,000 mg champignon mushroom extract against placebo, on a patient-reported visual analogue scale: MD −1.07 (95% CI −14.51 to 12.37), very low certainty — an interval so wide it excludes nothing. A topical gel — hinokitiol against placebo gel: MD −0.27 (95% CI −1.26 to 0.72), 1 trial, 18 participants. A mouthwash — chlorhexidine with zinc acetate: MD −0.20 (95% CI −0.58 to 0.18), 1 trial, 44 participants. Tablets: "no data were reported on key outcomes for this comparison." Every one of those intervals crosses zero. The single exception is a toothpaste — 0.3 per cent triclosan against a control toothpaste, MD −3.48 (95% CI −3.77 to −3.19), 1 trial, 81 participants — which is one very-low-certainty trial of 81 people, not a basis for buying anything. The review's overall verdict stands: "we do not have enough evidence to say which intervention works better to control bad breath." Spend the money on having the cause identified instead. See The truth and myths about mouthwashes

Practical details

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This page records a broadcast and its date, with general information. It is not a diagnosis or a treatment plan. Persistent halitosis should be assessed by a dentist, and by a GP where a non-oral cause is suspected. Figures quoted above come from published research on other populations and are not predictions about any individual. No individual's clinical information is published here. Third-party broadcast content is not reproduced.

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