How to prevent cavities in children: tips for parents

Tooth decay is one of the most common chronic conditions of childhood in Australia — and it is largely preventable. Here is what actually moves the needle.

Baby teeth matter

A common assumption is that decay in baby teeth does not count because they fall out anyway. It does count.

Baby teeth hold space for the adult teeth coming behind them. Losing one early can mean crowding later. Decay in a baby tooth is painful, can lead to infection, and can affect the developing adult tooth underneath. And decay in baby teeth is the strongest single predictor of decay in adult teeth — the habits and bacteria carry over.

Severe early childhood decay is one of the leading causes of hospital admission for young children in Australia, because treatment sometimes has to happen under general anaesthetic.

Brushing: the amounts that matter

Under 18 months — no toothpaste. Clean teeth with a soft brush and water as soon as the first one appears.
18 months to 6 years — low-fluoride children's toothpaste, pea-sized. Encourage spitting out; discourage swallowing and rinsing.
6 years and over — standard fluoride toothpaste, pea-sized amount.

The quantities matter: swallowing too much fluoride while adult teeth are forming can cause fluorosis, which shows as white flecking on the enamel. Where a child is at higher decay risk we sometimes recommend something different — follow what we have told you for your child.

Twice a day, and the night-time brush is the important one. Saliva flow drops during sleep, so anything left on the teeth sits there for hours.

Spit, do not rinse.

You need to do the brushing

This is the point most often missed. Children do not have the manual dexterity to brush effectively until around seven or eight.

Until then, brush their teeth for them, or let them have a go first and then go over it properly yourself. A good arrangement is to let them brush while you count, then say you are going to "check the back ones". You get the cleaning done; they keep some control.

Even after eight, supervise. Check the back teeth and the gumline.

And start cleaning between the teeth as soon as two teeth touch. Once there is contact, no brush reaches between them, and the contact points between the back molars are one of the commonest sites of childhood decay. Floss picks are easiest in a small mouth.

Frequency of sugar beats quantity

Every time a child eats or drinks something sugary, their mouth stays acidic for 20 to 40 minutes. Six small snacks do far more damage than the same food eaten at two meals.

So the most effective change is usually not banning treats — it is reducing the number of separate eating occasions.

Keep sweet things to mealtimes
Water between meals. Not juice, not cordial, not flavoured milk
Watch the ones marketed as healthy: fruit straps, dried fruit, muesli bars and juice boxes are among the more cavity-forming things in a lunchbox
Nothing but water in a bottle at bedtime. Milk, formula or juice pooling around the teeth overnight causes severe decay in the upper front teeth

The lunchbox, practically

Better	Worse	Why
Cheese, plain yoghurt	Yoghurt-covered bars, flavoured yoghurt	Sugar plus stickiness
Whole fruit	Fruit straps, dried fruit	Concentrated sugar that clings
Crackers with cheese or dip	Sweet biscuits	Frequency and stickiness
Nuts, boiled egg, sandwich	Muesli bars	Most bars are confectionery
Water	Juice box, flavoured milk, cordial	Sipped slowly, all day
Vegetable sticks	Fruit puree pouches	Pouches are sipped, and coat the teeth

A single treat at the end of lunch is far better for teeth than three "healthy" snacks grazed across the day. That is the whole principle, in one line.

Do not share saliva

Decay-causing bacteria are transmitted, usually from carer to child. Avoid sharing spoons, cleaning a dummy in your own mouth, or testing food temperature with the same spoon.

If you have untreated decay yourself, getting your own mouth healthy genuinely reduces your child's risk.

Fissure sealants

The grooves on the chewing surfaces of the back teeth are where most childhood decay begins — they are deep, narrow, and a toothbrush bristle cannot get into them.

A fissure sealant is a coating painted into those grooves. No drilling, no anaesthetic, quick to place. Usually considered soon after the first adult molars come through, around age six, and again around twelve. Cheaper and far less invasive than the filling it prevents. Ask us whether your child would benefit. See fissure sealants.

Fluoride

Melbourne's tap water is fluoridated, and tap water is the best routine drink for children. If you use tank or filtered water, mention it — some filters remove fluoride, which changes what we would recommend.

Fluoride varnish is a professionally applied coating, painted on in a minute or two at a check-up. No needles, no drilling, and it is one of the better-evidenced preventive measures for children at higher risk. Ask whether your child would benefit and how often.

Two things it is worth being clear about: fluoride works mainly by contact with the tooth surface rather than by being swallowed, which is why spitting and not rinsing matters; and fluoride supplements in tablet or drop form are not routinely recommended where the water supply is fluoridated.

How much risk does your child actually have?

The advice above is general. What your child needs depends on their risk, and the difference between a low-risk and a high-risk child is substantial.

Higher risk if:

They have already had decay, or a sibling or parent has had a lot
Brushing is inconsistent, or nobody is checking it
Snacking is frequent, or drinks other than water are available through the day
There is a bottle or sipper cup in bed
They have enamel defects, braces, or crowded teeth
They have a medical condition, a special need, or take sugar-containing medicine long term
They have a dry mouth, or mouth-breathe
They do not drink fluoridated tap water

More than two or three of these, and it is worth asking us for a proper risk assessment. The answer usually involves shorter recall intervals, varnish, sealants and a specific diet conversation — not just "brush better".

When the enamel itself is faulty

Worth knowing about, because parents often blame themselves for something that is not their doing.

Molar incisor hypomineralisation (MIH) is a developmental defect where the first adult molars — and sometimes the front teeth — come through with soft, chalky, creamy-brown or yellow-brown patches. The enamel is poorly formed from the outset, so it decays quickly, crumbles under chewing, and is often very sensitive.

It is not caused by poor brushing or too much sugar. It is common, and it is one of the reasons a six-year-old with conscientious parents can present with a badly broken-down first molar.

What helps: early identification, fluoride varnish, sealants where the tooth will hold one, sensitivity management, and a plan for the tooth's long-term future — which occasionally includes planned removal at the right age, coordinated with an orthodontist. If you see chalky patches on newly erupted molars, mention them.

If decay does happen

It is not a moral failure, and the options are broader than people expect.

Very early, white-spot decay — fluoride, cleaning and diet change, then monitored. No drilling
A small cavity — a tooth-coloured filling, sometimes without an injection, and sometimes with air abrasion rather than a drill
A larger cavity in a baby tooth — a filling, sometimes a preformed crown, which is more durable than a large filling in a small tooth
Silver diamine fluoride — a liquid that arrests decay without drilling. It stains the treated area black permanently, which is the trade-off. Genuinely useful for a very young or anxious child, or as a holding measure
Extraction, where a tooth cannot be saved. Sometimes followed by a space maintainer so the adult tooth keeps its room
Treatment under general anaesthetic, for extensive decay in a young child who cannot cooperate. Effective, and a bigger decision — with its own risks, costs and waiting times

Start visits early

First visit by around twelve months, or when the first tooth appears. Early visits are about familiarity and catching risk early, not treatment.

Eligible children aged 0–17 may be able to claim under the Child Dental Benefits Schedule — for eligible basic dental services over two consecutive calendar years. The cap depends on the start year; ask us to check eligibility and the balance, or see our CDBS guide.

Signs to look for

Check your child's teeth in good light every so often, including the inside surfaces and along the gumline:

Chalky white lines or spots, particularly near the gumline — the earliest sign, and reversible at this stage
Brown or black marks, or a visible hole
Complaints about cold, sweet things, or one side being sore
Suddenly refusing to have one area brushed — often a sore tooth rather than defiance
A gum boil or a pimple on the gum above a tooth — that is infection, and it needs seeing promptly
Bad breath from one particular area

White spots are worth acting on quickly. Caught then, decay can be remineralised without drilling.

Teenagers

Risk goes up rather than down, and supervision has gone.

Energy and sports drinks are the single biggest problem — sugar plus acid, sipped over time
Braces make cleaning genuinely hard. White marks around brackets are permanent
Independence means nobody is checking whether brushing happened
Vaping is not a neutral habit for gums or for dry mouth
Appearance and breath are more persuasive arguments than health at this age, and there is no harm in using them

Questions parents ask

Is it my fault? Usually not, and rarely entirely. Susceptibility varies, enamel defects happen, and some children are simply higher risk. What matters is what happens next.

Do baby teeth need fillings? Often yes — they are in the mouth for years, and decay in them hurts and spreads.

Can we just pull it out? Sometimes that is the right answer; often it is not, because losing a baby tooth early causes crowding later.

My child drinks only water and still got a cavity. Possible — grooves, enamel defects, or decay between teeth. Worth asking why rather than assuming effort was the problem.

Is fruit bad for their teeth? Whole fruit at mealtimes, no. Dried fruit, fruit straps and juice sipped across the day, yes.

How often should they be seen? Usually six-monthly, shorter where risk is higher.

Who provides this here

Victorian Dental Group is a general dental practice in Malvern East and holds no specialist registration. Children are seen by our dentists and oral health therapists. Where a child needs care beyond general practice — extensive treatment, care under general anaesthetic, or complex management — we refer to a registered specialist paediatric dentist.

Victorian Dental Group — 291 Wattletree Road, Malvern East VIC 3145 · (03) 9088 5808 · book online

General information only, not personal dental advice. See our disclaimer.

What prevents cavities in children more than anything else?

Two things: fluoride toothpaste used in the right amount twice a day, and keeping sugary food and drink to mealtimes. Everything else helps at the margins. If you change only one habit, make it the last thing at night — brush, then nothing but water afterwards.

How much toothpaste, and from what age?

Under 18 months, none — clean the teeth with a soft brush and water. From 18 months to six years, a pea-sized amount of low-fluoride children's toothpaste. From six years, standard family fluoride toothpaste. Teach them to spit and not rinse, so the fluoride keeps working, and store toothpaste out of reach so it is not eaten.

Is it the amount of sugar or how often?

How often, far more than how much. Every time sugar is eaten, the mouth turns acidic for a period afterwards, and it is the number of those episodes that determines decay. A chocolate bar eaten in one go at the end of a meal does less harm than the same sugar sipped or nibbled across an afternoon. Grazing and sipping are the real problem.

What about drinks?

Water and plain milk between meals — nothing else. Juice, cordial, soft drink, flavoured milk and sports drinks are both sugary and acidic. Never send a child to bed or to nap with a bottle or sipper cup of anything but water: saliva flow drops during sleep, and the drink pools around the teeth for hours. Melbourne tap water is fluoridated, which helps.

Which foods are better?

Cheese and plain yoghurt, crunchy fruit and vegetables such as apples, pears and carrots, and nuts for children old enough to eat them safely. Watch things marketed as healthy that are not, for teeth: dried fruit and fruit straps stick to the grooves, muesli bars are sticky and sweet, and fruit juice is sugar without the fibre.

Do I need to help them brush?

Yes, for longer than most parents expect — brush for them while they are small, and supervise and finish off until around age eight. Younger children simply do not have the dexterity. Standing behind them with their head tilted back gives you better access and light. Brushing together first, then finishing the job yourself, works better than a battle.

Why should I avoid sharing spoons and cups with a toddler?

Because the bacteria most associated with decay are transmitted, usually from a parent or carer, and a young child's mouth does not start out carrying them. Avoid sharing utensils, dummies and drink bottles, and do not clean a dummy in your own mouth. It also follows that treating your own untreated decay is one of the things that protects your child.

What can the practice do?

Fissure sealants on the permanent molars soon after they come through, fluoride varnish for children at higher risk, examination with X-rays where needed to find decay between the teeth, and practical advice tailored to how your child actually eats and brushes. Eligible children aged 0 to 17 can be treated under the Child Dental Benefits Schedule — bring their Medicare card. Victorian Dental Group, 291 Wattletree Road, Malvern East VIC 3145 — (03) 9088 5808.