How Much Fluoride Does a Child Actually Need?

A child needs a small, age-appropriate amount of fluoride left on the tooth surface every day — not a larger amount swallowed — which in Australia generally means a smear of low-fluoride toothpaste from around 18 months to five years and standard toothpaste from about six, with supervision. The rest of this article explains why the amount is dosed that way, and where drinking water and in-chair fluoride fit in.

Call

What does fluoride actually do?

It shifts a daily balance

Bacteria in the mouth feed on sugars and carbohydrates and produce acid. That acid dissolves minerals out of enamel. Saliva then works to put them back. Every day is a contest between the two, and for most people it stays roughly balanced.

Fluoride does not harden teeth by some separate mechanism. It tips that contest. It slows the rate at which minerals are lost, and it speeds up and improves the repair when they are replaced.

It changes the crystal that is rebuilt

When enamel remineralises in the presence of fluoride, the mineral that forms is more resistant to acid than the original. In practical terms, the surface can then survive an acid attack that would previously have started to break it down.

It works at the surface, not from the inside

This is the part that most changes how a parent should think about it. Fluoride's protective effect is largely topical — it happens where the toothpaste, varnish or fluoridated water actually contacts the tooth.

What is left behind on the teeth therefore matters more than what is swallowed. That single fact explains almost every piece of advice below.

The related process is described in more detail in the articles on what happens before a cavity hurts and on how early childhood decay begins.

How much toothpaste, at what age?

Australian guidance is expressed in general age bands, and it is deliberately conservative because young children swallow toothpaste rather than spit it out.

Children assessed as being at higher risk of decay are sometimes advised differently, including using standard toothpaste earlier. That is a decision made after an examination, not from an article. Follow your dental practicioners advice for your child.

Spit, do not rinse

After brushing, spit the excess out and stop there. Rinsing with water, or with mouthwash, washes away the thin film of fluoride that was about to do the work. This is one of the few changes that costs nothing and genuinely improves the result in most patients

Supervision is the other half

Most children under about eight do not have the manual control to clean the back teeth properly, however willing they are. Adult brushing at least once a day, usually at night, is what keeps the plaque off the surfaces a child misses.

Call

Does the water at home change the picture?

Sydney's mains supply is fluoridated

Water supplied to most of Sydney, including the Berala area, is fluoridated at a low level. For a family drinking mains tap water, that provides a small, steady background exposure across the day, which is exactly the pattern fluoride works best in.

Tank water and some filters do not

Rainwater tanks contain essentially no fluoride. Some domestic filters — particularly reverse osmosis and distillation units — remove most of it. Common carbon jug and tap filters generally do not remove fluoride, but the specification varies by product and is worth checking.

None of this means a child on tank or filtered water is destined to have decay. It means the background exposure is lower, and that is worth mentioning at an appointment so the assessment accounts for it.

Bottled water varies

Most bottled still water sold in Australia contains little or no added fluoride unless the label says so. A household that drinks mainly bottled water is, in effect, in a similar position to one on tank water.

General information on water fluoridation and children's oral health is published by the Australian Department of Health and healthdirect.

What is fluorosis, and how concerned should a parent be?

Dental fluorosis is a change in the appearance of enamel caused by taking in more fluoride than needed while the adult teeth are still forming under the gum — broadly, the first several years of life. Once the teeth have formed, it can no longer occur.

In Australia it is usually mild: faint white flecks or a slight mottling on the enamel, often only visible to someone looking for it. It is a cosmetic change. It does not weaken the tooth, and mild forms are, if anything, slightly more resistant to decay.

The reason toothpaste is dosed by age, and the reason children are taught to spit rather than swallow, is to keep total intake at the level that gives the protective effect without the cosmetic one. That is the whole purpose of the smear.

Swallowing some children's toothpaste occasionally is not a cause for alarm. Regularly eating toothpaste, or using an adult toothpaste from toddlerhood in large amounts, is the pattern the guidance is designed to avoid.

Where does in-chair fluoride fit?

Fluoride varnish is a concentrated fluoride painted onto the teeth at the end of a clean. It sets on contact with saliva, stays in place for several hours and releases fluoride into the surface during that time. It takes under a minute to apply and does not require any anaesthetic.

It is not a replacement for daily brushing. It is a periodic top-up on top of it, and it is most useful for children with early white-spot lesions, deep grooves, orthodontic appliances, a dry mouth, or a history of decay.

What it costs

Fluoride treatment is included in the fee for the check-up, X-rays and clean rather than billed on top of it. That appointment is $250 for an adult. For children who are not eligible for the Child Dental Benefits Schedule, it is $150 under the age of 10 and $250 from 10.

Those figures assume no health-fund contribution. A fund may contribute depending on the policy and the level of cover, and a written quotation is provided before treatment begins. The full list is on the fees page.

Many children are eligible for a capped benefit over two calendar years under the Child Dental Benefits Schedule, which is bulk-billed at this practice, meaning Medicare pays the clinic directly and there is no out-of-pocket cost for the services it covers. Eligibility can be checked using the CDBS checker.

Quick answers

Should my toddler use fluoride toothpaste?

Australian guidance generally introduces a low-fluoride children's toothpaste at around 18 months, in a smear, with an adult applying it. Whether that timing is right for a particular child depends on their decay risk, which is assessed at an appointment.

My child swallowed a mouthful of toothpaste. Is that dangerous?

A single swallow of children's toothpaste is not usually a concern. If a child has swallowed a large amount of toothpaste, or any fluoride supplement, contact the Poisons Information Centre on 13 11 26 or your doctor.

Do fluoride supplements or tablets help?

They are not routinely recommended in Australia for children in fluoridated areas, and they are not something to start without an assessment. If your water is untreated, raise it at your child's appointment rather than buying a supplement.

Is fluoride-free toothpaste a reasonable choice?

Toothpaste without fluoride cleans, but it removes the main reason toothpaste reduces decay. If a family prefers to avoid fluoride, that is worth discussing openly at an appointment so the rest of the prevention plan can be built around it.

Having your child assessed

Fluoride advice is only useful when it is matched to a particular child's decay risk, diet and water supply. That assessment happens at a check-up. More on children's services is on the paediatric dentistry hub.

Call

Written and reviewed by Humzah Aly, Oral Health Therapist. This article is general information only and is not a substitute for personalised dental advice. Please see a dental practitioner to discuss what is right for you.