Q&A with Kia Pajouhesh

Media item: interview, question-and-answer format

Date published: 29 November 2012

This page records the media item. The original interview is the property of its publisher and is not reproduced here.

In keeping with the format, what follows is general information in question-and-answer form — the questions people most often ask, answered plainly, including where the honest answer is inconvenient.

The questions everyone asks

"How often do I really need a check-up?"

Six months is a convention, not evidence. The right interval depends on your risk: your decay history, gum health, saliva, diet, smoking, medications and how well you clean. How often should I go to the dentist? works through the same reasoning.

Some people genuinely need three months. Some are safe at twelve or eighteen. Ask what interval is right for you, and why. 5 questions you've always wanted to ask your dentist covers a few more of them.

"Do I need X-rays every time?"

No. Radiographs are taken when they will change a decision — that principle is called justification and it is a regulatory requirement. The interval should follow your risk, not a calendar. See How safe are dental x-rays and How safe are dental X-rays and when do they become unsafe?

On the dose, the numbers are small and worth knowing. The International Atomic Energy Agency gives typical effective doses of 1 to 8 microsieverts for an intraoral dental X-ray, 4 to 30 microsieverts for a panoramic examination, and 2 to 3 microsieverts for a cephalometric one. Cone beam CT is the outlier: 50 microsieverts or below for small- or medium-sized scanning volumes, and around 100 microsieverts for large volumes — the IAEA notes that CBCT doses "cover a wide range, but may be tens or even hundreds of µSv of effective dose higher than conventional radiographic techniques". The IAEA also observes that doses at the high end of the conventional range are equivalent to a few days of natural background radiation, which is similar to a chest radiograph.

But refusing them altogether is not risk-free. Decay between back teeth and bone loss are invisible on visual examination. A great deal of dentistry cannot be done properly blind.

"Is fluoride safe?"

Yes, at the concentrations used in toothpaste and drinking water — and Australia has its own national assessment of this rather than an imported one. The National Health and Medical Research Council's 2017 Public Statement recommends community water fluoridation "as a safe, effective and ethical way to help reduce tooth decay", supports fluoridation within the range of 0.6 to 1.1 milligrams of fluoride per litre, and states that it found no evidence that community water fluoridation at current Australian levels causes human health problems. On effect size, the NHMRC found water fluoridation reduces tooth decay by 26 to 44 per cent in children and adolescents, and by about 27 per cent in adults. See The benefits of fluoride and Fluoridated water: is it good for you?, and Fluoridated water: why I worry for the other side of the argument.

The real, non-hypothetical risk is fluorosis — white or brown mottling from swallowing too much during the years teeth are forming. The 0.6 to 1.1 mg/L range is set precisely to balance the two: the NHMRC describes it as aimed at reducing tooth decay "while avoiding any risk of dental fluorosis of aesthetic concern". That is also why children's toothpaste is lower-strength and why the amount is a smear, then a pea, with the child taught to spit. Selecting a toothpaste — fluoride or non-fluoride? covers the choice.

"Should I brush before or after breakfast?"

If breakfast is acidic — juice, citrus, or after vomiting — do not brush immediately. Softened enamel abrades. Rinse with water and wait. Brushing your teeth: before or after breakfast? is the long answer.

The more important instruction is the one nobody is given: spit, don't rinse. Rinsing after brushing washes away the fluoride that would otherwise keep working for another hour or two. What is the ideal daily routine for oral hygiene? puts the whole routine in order.

"Does flossing actually do anything?"

The headlines claiming it does not were based on the absence of large high-quality trials, which is not the same as evidence of no effect. Is flossing really that important? goes through what the trials did and did not show.

What is clear: a toothbrush does not reach between teeth, and interproximal surfaces are where a large share of adult decay and gum disease starts.

On which tool, the Australian Dental Association does not pick a winner — its instruction is simply to "clean between your teeth daily with floss or interdental brushes", and no independent source we hold establishes that either is better than the other. Interdental brushes are usually easier where the spaces admit them; floss suits tight contacts. The best one is the one you actually use daily.

"Do I need an electric toothbrush?"

Oscillating-rotating electric brushes remove somewhat more plaque than manual brushing, and the effect is real but modest. Technique and consistency matter more than the device. A manual brush used well beats an electric one used badly — see Which toothbrushes do dentists recommend?

"Is charcoal toothpaste good?"

No. It whitens by abrasion, and abrasion removes enamel, which does not grow back. As enamel thins, more yellow dentine shows through — so long-term use makes teeth darker. Home whitening and charcoal whitening: does it work? Is it safe? has the detail.

"What about oil pulling?"

No good evidence of benefit — and worth being precise about what that means: no policy statement, guideline or trial on oil pulling appears in any of the independent sources we hold. It is not a substitute for brushing, and using it in place of treatment delays diagnosis. See Can oil pulling make my mouth healthier and my teeth whiter?

"Are my amalgam fillings dangerous?"

There is no good evidence that intact amalgam fillings harm health. Amalgam use has declined for aesthetic reasons and because of the Minamata Convention on mercury — an environmental treaty, not a patient safety finding. Dental fillings: porcelain, amalgam or composite resin? compares the materials, and Tooth Fillings sets out what is used here.

Removing sound amalgam fillings to "detoxify" is not supported by evidence, and it destroys tooth structure and releases more mercury vapour than leaving them alone.

"Do root canals cause cancer or chronic illness?"

No. This traces to the discredited early-twentieth-century "focal infection theory", abandoned decades ago because the research was unsound. Extracting healthy root-filled teeth on this basis is irreversible harm for no benefit. For what the treatment does achieve, the pooled figure is 87.8 per cent success at tooth level (95% CI 84 to 90 per cent), and 80.8 per cent at patient level. Everything you need to know about root canal treatment and Root Canal describe what the treatment actually involves; Dental Myths Exposed takes on the rest of the folklore.

"Why is dentistry so expensive?"

The honest answer has two parts.

The structural part: dental care sits largely outside Medicare. There is no general Medicare rebate for adult dental treatment, so you see the whole cost. A GP appointment costs roughly as much to deliver; you just do not see most of it.

The practice part: it is a small surgical facility. Sterilisation and its validated record-keeping, shielded radiography, medical-grade air and suction, treated waterlines, separated clinical and amalgam waste, laboratory fees, indemnity insurance, and a five- to eight-year training pathway.

None of which means you should not compare prices. Fees are unregulated and vary substantially between practices for the same treatment. Ask for the plan itemised with ASDS item numbers, which is what makes comparison possible — see the price guide and Understanding Your Treatment.

"Are cheap deals a bad sign?"

Not automatically. But a time-limited discount attached to irreversible treatment is exactly what the advertising rules exist to control, and it should slow you down rather than speed you up. Section 133 of the National Law prohibits advertising a regulated health service in a way that "offers a gift, discount or other inducement to attract a person to use the service or the business" unless the terms and conditions of the offer are stated, or that "directly or indirectly encourages the indiscriminate or unnecessary use of regulated health services".

"Should I get a second opinion?"

Yes, for anything extensive or irreversible. It is normal, reasonable, and any practitioner confident in their plan will not be troubled by it. You are entitled to your records and radiographs to take with you. See Second Opinions and Corrective Dentistry and What makes a truly great dentist?

"Does whitening damage teeth?"

The ADA's position is that peer-reviewed studies indicate peroxide-containing bleaching products "are safe and effective when used by or under the supervision of a dentist and according to the professional directions for use", and that "the most common side-effects are transient tooth sensitivity and soft tissue irritation during or immediately following treatment". Sensitivity is therefore the expected side effect, and it settles.

There is also a legal line worth knowing. Under Schedule 10 of the Poisons Standard, teeth whitening products containing more than 6 per cent hydrogen peroxide, or more than 18 per cent carbamide peroxide (one third of a carbamide concentration is roughly equivalent to hydrogen peroxide, so 18 per cent carbamide approximates 6 per cent hydrogen) may only be sold, supplied and used by registered dental practitioners as part of their dental practice. Those provisions are formalised in every state and territory's poisons legislation. Schedule 10 lists substances "of such danger to health as to warrant prohibition of their sale, supply and use other than in specified exempt circumstances".

The real problems are whitening over untreated decay or cracks, and the fact that whitening does not change the colour of any existing crown or filling — which may then need replacing to match. See Teeth Whitening, What should I know about teeth whitening? and I want to whiten my teeth but one of my front teeth has a porcelain crown.

"My gums bleed when I brush. Is that normal?"

No. Bleeding gums are the earliest sign of gum disease, which is painless until advanced, destroys bone that does not grow back, and is the leading cause of adult tooth loss. See Bleeding Gums and What is gum disease?

And keep brushing. Stopping because it bleeds is exactly backwards.

"I haven't been in ten years and I'm embarrassed."

This is one of the most common things practitioners hear, and the Australian data says so plainly. Armfield and colleagues analysed the 2002 National Dental Telephone Interview Survey — 6,112 Australians aged 16 and over — and found 11.9 per cent said they were very afraid of going to the dentist and a further 5.2 per cent quite afraid: roughly one adult in six. Fear rose across age groups up to 46–64 and then fell among those 65 and over.

The avoidance is measurable too. Of the very afraid, 43.9 per cent had last visited a dentist more than two years ago, against 29.1 per cent of those with no fear; 27.6 per cent expected to attend next only when they had pain or a problem, against fewer than 17 per cent of everyone else. The authors called it a vicious cycle, and the odds of fitting that profile were 3.33 times higher (95% CI 2.67 to 4.15) among the very fearful.

So: you are not unusual, and nobody competent will judge you. They have all seen it, and people in your position are usually the most motivated once they start. Say you are anxious when you book — it changes how the appointment is run. See Dental Anxiety and How can I ease my anxiety about visiting the dentist?

"What is the one thing that matters most?"

Fluoride toothpaste, twice a day, spit don't rinse — plus attention to sugar.

On sugar, the authorities frame it in two different ways and both are worth having. The World Health Organization sets a quantity target: limiting free sugars to less than 10 per cent of total energy intake, and ideally less than 5 per cent, "minimizes the risk of dental caries throughout the life course", and it defines free sugars to include sugars added by the manufacturer, cook or consumer plus those naturally present in honey, syrups and fruit juices. The Australian Dental Association's policy is broader and does not single out one variable: "the form, frequency, timing and total amount of sugar intake are significant in the initiation of the caries process", with particular emphasis on snacking on sugary drinks and sugar-rich foods of limited nutritional value. Frequency matters, in other words — but so does how much.

Everything else is a distant second.

Related pages: Dental Myth Busters, Fighting decay, Meshel & Tommy Show: Tommy's Appointment, General Dentistry, and the rest of the media record.

Practical details

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This page records a published interview and its date. The answers above are general information, not a reproduction of the original interview, and they are not a diagnosis or a treatment plan. Figures quoted are from the publishers named, apply to the populations and periods those publishers studied, and are not predictions about any individual. Third-party published content is not reproduced.

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