EasyCare dental guides · Cavities and decay
Tooth decay: signs, stages and treatment options
A cavity can start without pain. Learn what changes to notice, when early decay may be managed without a filling, and how a dentist chooses the right next step.
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The short answer: Tooth decay begins when plaque bacteria make acids from sugars and weaken tooth minerals. An early change can sometimes be arrested with fluoride and better daily habits. Once a true cavity forms, a dentist needs to assess whether the tooth requires a filling or another treatment. Pain is not a reliable measure of depth.
Understand the stages
What happens as tooth decay progresses?
01 / EARLY CHANGE
Minerals are lost
A chalky white area may appear as enamel loses minerals. This stage often causes no pain. If the surface has not broken down, fluoride, diet changes and monitoring may help stop or reverse the early damage.
02 / CAVITY
A hole develops
A cavity can trap food and may cause sensitivity to cold or sweet foods. A formed hole will not grow back. Treatment depends on its size, location and the strength of the remaining tooth.
03 / DEEPER DECAY
The nerve may be affected
Decay extending towards the pulp can cause lingering pain, pain on biting or infection. Some teeth need more than a filling; prompt assessment helps establish the available options.
A dark mark is not always an active cavity, and decay can occur between teeth where you cannot see it. Your dentist may use an examination and X-rays when clinically indicated.
Notice the change
What signs should you have checked?
- A visible hole, rough edge or food repeatedly catching in one spot
- Sensitivity to cold, heat or sweets, especially when it lingers
- Toothache, pain on biting or a bad taste with swelling
- A new white, brown or dark area that concerns you
Some cavities have no symptoms. If you can see a hole in a tooth without pain, arrange an assessment rather than waiting for an ache.
Other causes can feel similar
Sensitivity can also come from a crack, gum recession or tooth wear without decay. An examination matters more than guessing from a colour or symptom alone.
Reduce future risk
Can early decay be stopped?
Before a surface breaks down, fluoride and fewer frequent sugar exposures may help enamel regain minerals. Brush twice daily for two minutes with an age-appropriate fluoride toothpaste, clean between teeth and ask your dentist how often you need reviews. For children, use the toothpaste amount and strength recommended for their age.
Dry mouth can increase cavity risk because saliva helps protect teeth. If new decay appears alongside a persistently dry mouth, our dry mouth and medication guide explains what to discuss with your dentist and prescriber. Do not stop a prescribed medicine on your own.
For deep grooves on suitable back teeth, fissure sealants may be considered as part of prevention. A sealant or a clean does not repair an established cavity.
Choose care after diagnosis
How is a cavity treated?
A dentist checks whether a surface is sound, an early lesion can be monitored, or a cavity needs restoration. For a small or moderate cavity, see our tooth-coloured fillings page for the procedure and booking details. A weakened tooth may need a different restoration. If decay reaches the pulp, root canal treatment may be an option to save it; some teeth cannot be saved. The examination determines what is suitable.
When to seek help promptly
Call a dentist if pain is worsening, keeps you awake, or is linked with gum or facial swelling, fever or a bad taste. Our emergency dental care page explains the appointment pathway. If swelling spreads towards the eye or neck, or breathing or swallowing is affected, call 000 or go to an emergency department.
Common questions
Questions about tooth decay
Can a cavity heal on its own?
An early mineral change may improve, but a formed hole does not regrow. A dentist can tell which stage you have.
Does tooth decay always hurt?
No. Early decay and even some cavities can cause no pain. Waiting for pain may allow the problem to progress.
Will I definitely need a filling?
No. An early, unbroken lesion may be monitored and managed preventively. A formed cavity often needs restoration, depending on the examination.
Is decay the same as acid erosion?
No. Decay involves plaque bacteria and sugars; erosion is direct acid wear from sources such as acidic drinks or reflux. Both can occur together.
Further reading: NIDCR on tooth decay. This guide cannot diagnose an individual tooth.
