How tooth decay actually happens

Tooth decay happens when bacteria in plaque turn sugar into acid, which dissolves the mineral in your tooth’s enamel. It starts as a “white spot” and becomes a cavity once the surface breaks down.

Where it starts: plaque

Plaque is the soft film that builds up on your teeth every day. It has to be removed regularly — brushing and flossing — because it contains bacteria that turn the carbohydrates you eat into acid.

Why frequency matters more than quantity

Every time you eat something sugary, the acid level in your mouth rises. Below a critical pH of about 5.5, minerals start leaching out of your teeth. If you snack often, your mouth never gets enough time to recover between acid attacks, and the net effect over weeks is mineral loss you can see as a white spot on the tooth.

At this early stage, the surface is still intact and the damage can be reversed with fluoride. Left untreated, the surface eventually breaks down into a cavity — and once there’s a hole, it needs a filling.

What decides your risk

• Diet — how often you have sugar matters more than how much. Aim for at least a two-hour gap between snacks.
• Plaque — how much builds up, and how often it’s removed.
• Saliva — its ability to neutralise acid and supply calcium and phosphate back to your teeth varies person to person.
• Fluoride exposure — from toothpaste, varnish or gel, which strengthens enamel against acid.

What actually helps

Cutting back on sugar and snacking less often reduces the number of acid attacks your teeth face each day. A fluoride toothpaste, used twice daily, works even between check-ups. And a regular dental visit catches early decay while it’s still reversible — ask your dentist what’s right for you.