What is it?
Bacteria in your mouth produce acid as they process sugar, and that acid dissolves mineral out of the enamel. Saliva works all day to put it back; when dissolution outpaces repair, first a white spot and then a cavity forms.
The critical point: at the white-spot stage the process is still reversible; fluoride and dietary change can remineralise the enamel. Once a cavity forms there is no way back and a filling is needed. Pain is the last symptom to arrive; a painful cavity has usually reached the nerve.
Signs
You will not necessarily have all of these at once.
Why does it happen?
- 01
How often you eat sugar, not how much
Snacking six times a day is far more damaging than eating the same amount at once; each time the mouth turns acidic again.
- 02
Not cleaning between the teeth
In adults, most decay begins between the teeth where a brush never reaches.
- 03
Dry mouth
Saliva is the mouth's natural buffer. Some medications reduce it and multiply decay risk several times over.
How does it progress?
- 1
White spot
Enamel is losing mineral but the surface is intact. Reversible with fluoride.
- 2
Enamel decay
The surface has collapsed into a cavity. No pain yet, but a filling is needed.
- 3
Dentine decay
Decay reaches the softer tissue beneath. Sensitivity starts and progress speeds up.
- 4
Nerve involvement
Throbbing pain. A filling is no longer enough; root canal treatment is required.
How is it treated?
At the white-spot stage the treatment is fluoride varnish and dietary change; nothing is drilled. Once a cavity exists, the decayed tissue is removed and the space restored with a composite filling in a single visit.
If decay has reached the nerve, root canal treatment is required, and where much tooth structure is lost the tooth is then protected with a crown. This is why six-month check-ups aren't a formality; the difference is between a filling and a crown.
How is it prevented?
- Take sugary and acidic drinks with meals rather than spread between them
- Use fluoride toothpaste and don't rinse with water afterwards; let the fluoride stay
- Floss or use an interdental brush daily; most cavities start there
- Six-monthly check-ups; decay is only visible on examination before it hurts
Frequently asked questions
- Does a painless cavity need treating?
- Yes, in fact that is exactly when it should be treated. Pain signals that decay has reached the nerve; treating it beforehand is far simpler and cheaper.
- Can decay stop by itself?
- Only at the white-spot stage, and only if conditions change. Once a cavity has formed it will not stop on its own and must be cleaned out.
This content is for general information and does not replace an in-person examination. Symptoms overlap between conditions, and a diagnosis can only be made clinically.