Ten ways to prevent tooth decay, in order of how much they matter

Most lists like this present ten items as if they matter equally. They do not.

Two of these do more than the other eight put together. The rest are worth doing, but if you only ever change two things, change the first two.

1. Use fluoride toothpaste, and spit rather than rinse

Fluoride is the single most effective thing you can put on a tooth. It hardens enamel against acid and helps rebuild the surface where it has begun to soften.

The part almost everybody gets wrong takes one second to fix. Do not rinse your mouth out with water after brushing. Spit out the excess and stop there. Rinsing washes away the fluoride you just applied, which is most of what you were brushing for.

For children, a smear of low-fluoride children's toothpaste under three and a pea-sized amount after that, and teach them to spit rather than swallow.

2. Cut how often you eat sugar, not how much

Every time you eat or drink something sweet, bacteria produce acid, and it takes your saliva a while to wash it away and put minerals back.

So the number that matters is how many separate times a day that happens, not the total on the label.

One biscuit with a cup of tea is one acid attack. The same biscuits picked at over an hour is many, with no recovery between them. A sipped soft drink at your desk is the worst version of all, because it never stops.

Practical version: sweet things at mealtimes, water in between, and never nurse a sweet drink.

3. Clean between your teeth once a day

A toothbrush cannot get between two teeth that touch. No brush can, at any price.

Those contact points are where a large share of decay starts, precisely because nothing disturbs them. Floss, interdental brushes or a water flosser all work. The tool matters far less than doing it.

4. Brush properly, not harder

Two minutes, twice a day, with a soft brush angled about forty-five degrees into the gum line, using small circles.

Gently. Hard brushing does not clean better and it wears enamel and pushes the gums back, exposing root surfaces that decay faster than enamel does. If your brush splays within a month or two, you are pressing far too hard.

Never skip the night brush. Saliva flow drops while you sleep, so anything left behind sits there for eight hours with your defences down.

5. Drink water, especially tap water

Water rinses away food and acid, and it keeps your mouth from drying out.

Most Australian mains water is fluoridated, which adds a small ongoing benefit throughout the day. Bottled water usually is not. That is not a reason to panic about bottled water, just a reason not to assume they are identical.

If your mouth is dry a lot, mention it. Dry mouth is a large and underestimated cause of decay in adults, and it is very often a side effect of medication rather than anything you are doing.

6. Ask about sealants for children

The chewing surfaces of back teeth have deep narrow grooves, sometimes narrower than a single toothbrush bristle. A great deal of childhood decay starts in exactly those grooves, because they cannot be cleaned properly.

A sealant is a thin coating that fills them in, applied without drilling or numbing. For children with deep grooves it is one of the highest-value preventive treatments there is. Ask at your child's next visit whether their teeth would benefit.

7. Sugar-free gum after meals

Chewing prompts saliva, and saliva neutralises acid and carries minerals back to the tooth.

It is genuinely useful when you have eaten and cannot brush, which for most people is lunch on a workday. It is not a replacement for brushing, and it needs to be sugar-free to work.

8. Do not smoke

Smoking's main dental damage is to gums rather than to enamel, but it is on this list because it reduces bleeding, which is the early warning sign for gum disease. Losing the warning means problems are found later and further along.

It also slows healing, which makes any treatment you eventually need harder.

9. Watch acidic drinks, including the sugar-free ones

Decay and erosion are different processes with different causes. Sugar-free soft drinks solve the first problem and not the second, because they are still acidic and acid dissolves enamel directly.

Sparkling water, citrus, juice, wine and sports drinks all count. Drink them with meals rather than sipping, use a straw for cold ones, and do not brush for about an hour afterwards, because softened enamel brushes away.

Read more: What causes dental erosion

10. Start children early, and keep going

Wipe the gums before there are teeth. Brush from the first tooth. First dental visit by the first birthday.

Children need help brushing until about seven or eight, because the wrist control is not there before then. Let them go first and you finish.

The one that is not a habit

Early decay is reversible. A cavity is not.

That distinction is the whole reason for check-ups. Between teeth, where most adult decay starts, you cannot see it and neither can we without an x-ray. By the time it hurts, the conversation has usually moved from a filling to a root canal.

A full check-up and clean is a fixed $249, covering the exam, the scale and clean, fluoride and any bitewing x-rays you need, with your health fund claimed on the spot.