What decay actually is
Tooth decay is not sugar dissolving teeth. It is bacteria in dental plaque feeding on the sugars and refined carbohydrates you eat, and producing acid as a waste product. That acid pulls minerals out of the enamel — demineralisation. Saliva spends the hours between meals slowly repairing the damage — remineralisation. Decay happens when the attacks outpace the repairs: a running battle your mouth fights every day, decided mostly by how often acid is produced and how well plaque is removed.
Why frequency beats quantity
Each sugar exposure triggers an acid attack that takes roughly 20 to 30 minutes to neutralise. Eat a chocolate bar in five minutes and your teeth weather one attack. Graze the same bar across the afternoon, or sip a sugary or acidic drink across the day, and your teeth sit in acid for hours. This is the single most useful fact in this guide: keeping sugar to mealtimes — when saliva flow is high and buffering is strongest — dramatically reduces decay without requiring you to eat less sugar overall. The same logic applies to fruit juice, sports drinks, and sugar in tea and coffee drunk slowly across the morning.
The stages — and where reversibility ends
Stage 1: the white spot. Early demineralisation appears as a chalky white patch. No cavity exists yet, and this stage is reversible — fluoride, plaque control and diet change can re-harden the enamel. Stage 2: enamel cavity. The surface breaks; a hole exists. From here, no amount of brushing repairs it — the tooth needs a filling (from £127.50). Usually painless, which is why check-ups catch what you cannot feel. Stage 3: dentine decay. Beneath the enamel, the softer dentine decays faster; sensitivity to sweet and cold appears. Stage 4: pulp involvement. Bacteria reach the nerve — toothache arrives, and the choice narrows to root canal treatment (from £340) or extraction (from £144.50). Stage 5: abscess. Infection at the root tip; swelling and significant pain. The arc of decay is an arc of rising cost and shrinking options, which is the entire argument for early detection.
Where decay hides
The grooves of the back teeth, the contact points between teeth where a brush cannot reach, around the edges of old fillings and crowns, and — increasingly with age — on root surfaces exposed by gum recession, which decay faster than enamel. Between-teeth decay is invisible to the eye, which is why routine X-rays at check-ups (from £60) are not an upsell but the only way these lesions are caught small.
Prevention that actually works
Fluoride toothpaste, used correctly: brush twice daily, last thing at night and one other time, and spit — don't rinse. Rinsing washes the fluoride away and undoes half the benefit. Clean between teeth daily with interdental brushes or floss: the brush never reaches where most adult fillings begin. Confine sugar and acid to mealtimes, with water, tea or coffee without sugar between meals. Chewing sugar-free gum after meals stimulates saliva, the mouth's own repair system. Attend check-ups at the interval we recommend — catching stage 1 instead of stage 3 is the cheapest dentistry there is.
Children, adults, and the high-risk years
Children's newly erupted teeth are vulnerable, which is why early habits and fluoride matter so much. But adult decay deserves equal attention: dry mouth from common medications removes the saliva defence, gum recession exposes root surfaces, and old fillings develop leaky margins. If you take regular medication and have noticed a drier mouth, tell us — your decay risk has changed and your prevention should too.
What treatment looks like at each stage
Early white-spot lesions: enhanced fluoride and monitoring — no drilling. Established cavities: composite fillings (from £127.50), matched to the tooth colour. Larger breakdowns: onlays or crowns (from £590.75). Nerve involvement: root canal treatment (from £340) and usually a crown. Our consistent position is minimum intervention — the smallest restoration that solves the problem — because every filling has a lifespan, and the less tooth removed today, the more options remain for the decades ahead.