Dental myths exposed

How many of these have you heard? And how many do you believe?

“You only need a dentist when your teeth hurt”

One of the difficulties of dental disease is that many conditions begin and worsen over time without signs or symptoms. Decay moves quietly through the stages of dental decay long before it reaches the nerve, and periodontal (gum) disease can destroy bone without hurting at all until it is advanced.

Even with no pain, see your dentist twice a year for a thorough examination, so problems are caught while they are still small. Conditions that are asymptomatic can still need urgent treatment.

If they are not addressed early, you may need more complex and expensive treatment — the gap between a filling and a crown or root canal is visible in the price guide — and be at risk of permanent tooth loss, at which point the question becomes which of the replacement options for missing teeth suits you, rather than how to keep your own.

The old saying — prevention is better than cure — could not be truer here, because the alternative is not “treat it later”, it is “treat something worse later”. See General Dentistry and How often should I go to the dentist? — and note that the right interval depends on your risk rather than being six months for everyone.

“Flossing creates spaces between your teeth”

Flossing correctly does not create spaces. In fact it helps prevent decay and gum disease in areas your toothbrush cannot reach.

What gives rise to the myth: when you first start flossing you may notice some bleeding. That indicates inflammation already built up in the area — not damage from the floss. A few weeks of steady flossing usually resolves it.

People often stop at exactly the point they should continue. See Bleeding Gums and Is flossing really that important?.

One caveat worth knowing: floss that shreds or catches in the same spot every time is not a flossing problem — it usually means a broken filling edge or a cavity between the teeth, and it needs looking at. See Tooth Fillings.

“Baby teeth don’t need to be brushed”

Arguably baby teeth are the most important of all.

They provide the space for adult teeth to come through in alignment. Premature loss may leave inadequate space for the adult teeth, causing crowding and the need for time-consuming orthodontic correction later — a good deal of the children’s braces and Invisalign work done on teenagers is undoing space that was lost years earlier.

There is a second consequence people rarely hear: an infected baby tooth may cause defects in the corresponding adult tooth, making it more prone to infection when it erupts.

And the habit point: if a child is not in the habit of brushing and flossing, they are unlikely to be in the habit of caring for their adult teeth either.

See Children’s Dentistry and Kids Teeth Cleaning Tips. For eligible families, the Child Dental Benefits Schedule covers examinations, cleans and fillings for children who are 0 to 17 years old for at least one day that calendar year, as Services Australia sets the eligibility rule.

“Sugar only matters if you eat a lot of it”

Amount is one of four things that matter, and on its own it is the least useful to think about.

The Australian Dental Association’s position is that “the form, frequency, timing and total amount of sugar intake are significant in the initiation of the caries process”. Frequency and timing are the two most people leave out. A single serve of something sugary with a meal behaves quite differently from the same amount sipped across an afternoon, because each exposure drops the pH of the plaque below the point at which tooth structure begins to soften, and the mouth needs time between exposures to recover. The ADA singles out sipping drinks other than water during interrupted sleep as a specific risk, and asks that public education put “special emphasis … on the form, frequency, timing and total amount of sugar consumption”, particularly snacking on sugary drinks and sugar-rich foods of limited nutritional value.

The definition catches people out too. The World Health Organization’s term is free sugars — all monosaccharides and disaccharides added by the manufacturer, cook or consumer, plus sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates. Honey and juice are in, which is not what most people assume when they cut out “sugar”.

WHO’s guidance, in both adults and children, is a strong recommendation to reduce free sugars to less than 10% of total energy intake, with a further suggestion that going below 5% further decreases the risk of tooth decay. It describes the consumption of free sugars as “the most common risk factor for dental caries”, and recommends that children under 2 years of age should not consume any sugar-sweetened beverages at all.

See How does sugar affect your dental health?, does sugar damage teeth?, are sugar-free soft drinks better for your teeth?, does chewing sugar-free gum really help prevent cavities? and How does your diet affect your teeth?.

“Fluoride in the tap water is dangerous”

This one has the most independent evidence behind the answer of anything on this page, so it is worth setting out precisely rather than waving at.

In 2016 the National Health and Medical Research Council completed a review of the scientific research relevant to Australia on any link between water fluoridation and human health, and in November 2017 published its Public Statement: Water Fluoridation and Human Health in Australia. The NHMRC “confirmed that community water fluoridation helps to reduce tooth decay, and that there is no reliable evidence that water fluoridation at current Australian levels causes health problems”, and recommends it as “a safe, effective and ethical way to help reduce tooth decay”.

The measured effect: the NHMRC found that water fluoridation reduces tooth decay by 26 to 44% in children and adolescents, and by about 27% in adults. It supports Australian states and territories fluoridating supplies within the range of 0.6 to 1.1 milligrams of fluoride per litre — a range chosen to reduce decay while avoiding any risk of dental fluorosis of aesthetic concern.

On the specific health claims that circulate, the NHMRC reports no reliable evidence of an association between community water fluoridation as practised in Australia and chronic kidney disease, kidney stones, atherosclerosis, high blood pressure, low birth weight, all-cause mortality, musculoskeletal pain, osteoporosis, skeletal fluorosis or thyroid function including goitre and hypothyroidism, and no association with hip fracture. On fluorosis itself: moderate dental fluorosis is very uncommon in Australia and severe dental fluorosis is rare, and the small amount seen in children aged 8 to 14 is not statistically different between fluoridated and non-fluoridated areas.

The honest footnote, because it matters and is usually skipped: the NHMRC uses the phrase “no reliable evidence” as a defined term, meaning it lacked confidence that the evidence reviewed was relevant to Australia or valid enough to accept an association. That is not the same sentence as “proven to have no effect”, and anyone quoting the review — in either direction — should quote it as written.

See Fluoridated water: is it good for you?, fluoridated water: why I worry, the benefits of fluoride and selecting a toothpaste: fluoride or non-fluoride?.

“White teeth are healthy teeth”

White teeth are something most people want, but whiteness has no correlation with health.

Natural tooth colour varies in lightness because of age, diet, and tooth and gum health — how can I improve the whiteness of my teeth? goes through what genuinely changes shade and what does not.

So having white teeth does not mean you can stop routine examinations and professional cleans — you can have bright teeth and active decay or gum disease at the same time. See Dental Cleans & Hygienists.

“Whitening damages your teeth”

Modern whitening carried out by a qualified dental practitioner, using approved whitening agents, is considered safe for teeth and gums.

Your dentist will give you pre- and post-operative instructions for a day or two afterwards, which reduce side effects such as temporary tooth sensitivity.

The real risk lies elsewhere: in products that are not regulated or approved. Unapproved home whitening agents may damage your enamel, harming your oral health — home whitening and charcoal whitening looks at what those products actually contain.

Where the law actually draws the line

This is the part that turns a vague warning into something you can check on a label.

Schedule 10 of the Poisons Standard lists substances “of such danger to health as to warrant prohibition of their sale, supply and use other than in specified exempt circumstances”. Teeth whitening products sit in it above a threshold: Schedule 10 states that products containing more than 6% hydrogen peroxide or 18% carbamide peroxide “may only be sold, supplied and used by registered dental practitioners as part of their dental practise”. The Australian Dental Association notes those provisions are formalised in all state and territory poisons legislation.

The two numbers travel together for a chemical reason: carbamide peroxide is roughly one-third hydrogen peroxide by effect, so 18% carbamide peroxide approximates 6% hydrogen peroxide. Concentrations in use span a wide range — the ADA describes products as low as 3–6% for some supplied to patients for home use, up to 35% in some office-based bleaching products. It also notes that while weak solutions of under 3% hydrogen peroxide have been used in the mouth in mouthwashes and toothpaste for many years with few problems, “the potential for adverse effects on the oral tissues is increased when higher concentrations are used”.

So the myth has a grain of truth attached to the wrong thing. The procedure is not the danger; concentration, and who is legally permitted to supply it, is what the regulation is actually about. If a product is strong enough to work quickly and is being sold to you by someone who is not a registered dental practitioner, those two facts are in tension. See Teeth Whitening and Home whitening versus having your teeth whitened at the dentist.

One thing whitening does not do: lighten crowns, veneers or fillings. If you have restorations on the front teeth, whitening changes the teeth around them and leaves the restorations where they were — which is why whitening comes before that work, not after. I want to whiten my teeth but one of my front teeth has a porcelain crown deals with that exact situation.

“Braces are only for kids”

Most of us grew up seeing orthodontic treatment mainly in children, but it is increasingly common for adults.

The usual hesitations:

• the appearance of traditional braces
• the cost
• the time it takes to get results

The “train track” era is over. Advances in 3D scanning and printing have made clear aligner technologies such as Invisalign a discreet way for adults to correct problems they did not have the opportunity to address earlier. See Is having Invisalign as an adult worth it? and Braces.

On the cost objection, payment plan options are available. Where a plan is advertised as interest free, that describes the plan term only — a deposit may be required, an establishment fee and ongoing account fees may apply, and charges can apply if the balance is not cleared within the agreed period. The applicable terms depend on the provider and the amount financed, and are set out in writing before you commit — ask what the deposit and the establishment fee are, in dollars. See Payment Plans and What is the cost of braces?.

One genuine difference in adults, rather than a myth: gum health has to be stable before teeth are moved, and existing crowns, bridges and dental implants change what is possible — an implant does not move at all.

The underlying point

Be proactive. It is always better to stop problems before they occur than to deal with disease and pain afterwards.

A few minutes each day saves hours of pain and trouble later — and a considerable amount of money.

The other thing worth noticing about the myths above: the ones with the strongest independent evidence behind them are the ones people argue about most. Fluoride and sugar have been studied for decades by bodies with no commercial interest in the answer. Where a claim about your teeth matters enough to act on, it is usually worth finding out whether a regulator or a research council has already published on it — and reading what they actually wrote rather than what was written about it.

And if the reason you have not been is fear rather than belief in any of the above, say so when you book — it changes how the appointment is run. See Dental Anxiety.

Common questions

“Dental x-rays give you a lot of radiation.” Do they?

The doses are published, and they are small enough that the useful comparison is a day or two of the background radiation everybody receives anyway.

The International Atomic Energy Agency gives typical effective doses for dental imaging as:

• intraoral dental x-ray: 1–8 μSv
• panoramic examinations: 4–30 μSv
• cephalometric examinations: 2–3 μSv
• CBCT: 50 μSv or below for small or medium scanning volumes, and 100 μSv for large volumes (based on median values from the literature)

The IAEA's own summary of what that means: “the doses from intraoral and cephalometric dental radiological procedures are lower, usually less than one day of natural background radiation,” while panoramic doses are more variable but “even at the high end of the range are equivalent to a few days of natural background radiation which is similar to that of a chest radiograph.” CBCT is the one that genuinely varies, and the IAEA notes it “may be tens or even hundreds of µSv of effective dose higher than conventional radiographic techniques, depending upon the technique.”

This explains an apparent contradiction people notice between different dental pages: a figure of 0.001–0.008 mSv and a figure of 0.004–0.030 mSv are both correct, because the first is an intraoral film and the second is a panoramic. Always check which examination a number refers to.

The right question is therefore not “how much radiation?” but “what will this image change?” Every radiograph should be individually justified, and you are entitled to ask why this one, now, and what decision it will inform. See How safe are dental X-rays?

“Everyone has to get their wisdom teeth out eventually.” Is that right?

No — and this is one of the few places where the honest answer is that the evidence does not settle it.

The relevant Cochrane review on asymptomatic, disease-free impacted wisdom teeth concludes that “insufficient evidence is available to determine whether asymptomatic disease-free impacted wisdom teeth should be removed or retained,” adding that although retention “may be associated with increased risk of periodontitis affecting adjacent second molars in the long term, the evidence is very low certainty.” Its advice for practice is explicitly shared decision-making, and — importantly — that if the decision is to retain them, “clinical assessment at regular intervals to prevent undesirable outcomes is advisable.” Retaining is not the same as ignoring.

The United Kingdom's NICE technology appraisal TA1, published on 27 March 2000, went further for the NHS: “the practice of prophylactic removal of pathology-free impacted third molars should be discontinued,” and surgical removal “should be limited to patients with evidence of pathology.” TA1 lists what counts as pathology — unrestorable decay, untreatable pulp or periapical disease, cellulitis, abscess or osteomyelitis, resorption of the tooth or its neighbour, fracture, disease of the follicle including a cyst or tumour, and teeth obstructing jaw surgery. On the most common real-world trigger it says a first episode of pericoronitis, unless particularly severe, should not in itself be an indication for surgery, while second or subsequent episodes should be.

Two cautions on that. TA1 is UK NHS guidance from 2000 and has no status in Australia. And the argument is not one-sided: NICE also records that every removal carries risk — temporary or permanent nerve damage, dry socket, infection and bleeding, plus the risks of a general anaesthetic where one is used.

So it is a genuine decision with arguments on both sides, taken on your own radiographs, not a rite of passage. Ask what pathology is actually present, and if the answer is none, ask what the monitoring plan is. See Wisdom Teeth.

“A root canal never really works — you may as well pull the tooth.”

The published figures do not support that.

A long-term retrospective study of 598 endodontically treated teeth in 312 patients reported overall success of 87.8% (95% CI 84–90%) at the tooth level and 80.8% (95% CI 75–86%) at the patient level, with cumulative success by life-table analysis of 93% at 10 years, 85% at 20 years, 81% at 30 years and 81% at 37 years. Success was not significantly affected by which tooth it was, or by whether it was in the upper or lower jaw.

What the same study found does matter is what happens around and after the treatment. The strongest predictors of eventually losing the tooth were deep periodontal pockets of 6 mm or more, a pre-operative apical radiolucency, and the absence of occlusal protection — that is, not wearing a night guard where one was indicated. The restoration placed afterwards matters more than the material it is made from: the study found no difference in tooth survival between crowned teeth and direct fillings once the amount of remaining tooth structure was accounted for.

One honest caveat the literature itself raises: reported success rates vary widely because researchers define success differently. Pooled rates have ranged from 74.7% (95% CI 69.8–79.5%) under strict radiographic and clinical criteria to 85.2% (95% CI 82.2–88.3%) under looser ones — a gap of about 10.5 percentage points created by the definition alone. So compare like with like when you read a number.

See Root canal treatment, what does root canal treatment involve? and, for the comparison against removing the tooth, replacement options for missing teeth.

“A good mouthwash does the same job as brushing.”

It does not, and the sources are unusually blunt about it.

Australian Prescriber states that “mouthwashes are an adjunct to, not a substitute for, regular brushing and flossing” and that a mouthwash “should never be the sole means of oral hygiene.” Where trials have found a benefit from an antiseptic rinse, it was tested as an adjunct to mechanical oral hygiene procedures — meaning on top of brushing, not instead of it.

The mechanism is the reason. Plaque is a biofilm: a structured bacterial community bonded to the tooth surface, not loose debris floating about. Rinsing does not disrupt it; a brush and interdental cleaning do. And once plaque has mineralised into calculus, nothing you use at home removes it at all.

That is not an argument that mouthwash is useless — the same sources describe specific, real uses for particular rinses in particular situations, prescribed for a reason and often for a limited period. It is an argument that it cannot be swapped in for the thing it is meant to sit alongside. See The truth and myths about mouthwashes and What is the ideal daily routine for oral hygiene?

“Bad breath means someone isn't brushing.”

Usually it means something more specific than that, and it is worth knowing because the wrong fix does not work.

Better Health Channel, Victoria's state health information service, states that “halitosis is caused by sulphur-producing bacteria in the tongue and throat,” and that the gases responsible are released from the back of the tongue and throat. The signs it lists include a white coating especially at the back of the tongue, dry mouth, build-up around the teeth, post-nasal drip, and morning bad breath. It also says plainly that halitosis is not infectious — you cannot catch it, and it is not a hygiene failing in the way people assume.

What follows practically is that brushing the teeth harder is not the intervention. Gentle but thorough tongue cleaning — brushing or scraping from the back of the tongue towards the front — addresses where the bacteria actually are. Dry mouth is the other common driver, and it has causes of its own that are worth identifying rather than masking: see My mouth always feels dry — what can I do?

And persistent bad breath that does not respond to any of that is a reason to be examined rather than to buy a stronger rinse. Gum disease, an untreated cavity and several non-dental causes all present this way. See Bleeding Gums.

Related reading

• How do I prevent dental decay?
• How long do teeth whitening effects last?
• Emergency Dentistry — for the problems that will not wait for a routine appointment

Practical details

Written by Dr Avi Aggarwal (DEN0002313495), Registered Dentist, General Registration, Smile Solutions. Dr Aggarwal’s registration can be verified free on the AHPRA public register at ahpra.gov.au.

Smile Solutions, Level 1, 220 Collins Street, Manchester Unity Building, Melbourne VIC 3000. Phone 13 13 96, or theteam@smilesolutions.com.au. Monday–Friday 8.00am–6.00pm, Saturday 8.30am–1.30pm, Sunday by appointment. Full details on Contact Us.

Published 14 October 2020. Whitening results and suitability vary between individuals. Material attributed to the NHMRC is from its 2016 review and 2017 Public Statement on water fluoridation; to the World Health Organization from its guidance on sugars and dental caries; and to the Australian Dental Association from its policy statements on dietary sugars and on teeth whitening. Those are third-party documents, not Smile Solutions material, and are revised over time. Schedule 10 of the Poisons Standard is administered by the TGA and given effect in state and territory poisons legislation; check the current instrument rather than relying on a summary. Child Dental Benefits Schedule eligibility and coverage are set by Services Australia and change. Payment plan terms are set by the credit provider and change; confirm current terms directly before you commit. Dose figures in the questions above are from the International Atomic Energy Agency; the wisdom-teeth evidence from a Cochrane review and from NICE technology appraisal TA1 (United Kingdom, 27 March 2000, which has no status in Australia); the endodontic figures from a published longitudinal study; the mouthwash position from Australian Prescriber; and the halitosis material from Better Health Channel, Victoria. General information only; it does not replace advice from your treating practitioner.

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