Gloss & Floss Answers · Root Canals, Fillings & Crowns
Can a filled tooth get a cavity again?
Direct answer
Yes, a filled tooth can get a cavity again. Decay can develop around the edges of an old filling, under a leaking filling or on another surface of the same tooth. This is called recurrent decay when it occurs near an existing restoration. Regular check-ups, good cleaning, fluoride and early repair of leaking margins help reduce the risk.
Why fillings do not make teeth immune
A filling repairs damage that has already occurred, but the remaining natural tooth can still be affected by plaque, sugar, acid, dry mouth and leakage.
Over time, filling edges can wear, chip or open microscopically. If bacteria enter the gap, decay can start around or under the restoration.
How decay returns around fillings
| Situation | What happens | Why it matters |
|---|---|---|
| Leaking margin | A gap opens between filling and tooth. | Bacteria can enter and decay may develop underneath. |
| New surface decay | Another part of the same tooth gets decay. | The filling is intact but the tooth remains at risk. |
| Broken filling edge | Food and plaque trap around the defect. | The area may need repair or replacement. |
| Dry mouth | Less saliva protection increases decay risk. | Extra prevention may be needed. |
| High sugar frequency | Repeated acid attacks affect tooth surfaces. | Diet timing and fluoride become important. |
Signs a filled tooth should be checked
- Food trapping near the filling.
- Floss catching or tearing.
- A rough edge you can feel with your tongue.
- Sensitivity to sweet, cold or biting.
- Dark line or shadow around a filling.
- Bad taste or smell from one area.
- A piece of filling or tooth breaking off.
- Pain that comes and goes.
What happens at Gloss & Floss Dental Care®?
At Gloss & Floss Dental Care® in Stockholm, we check existing fillings during examinations and may use X-rays to detect decay between teeth or under restorations.
Treatment depends on the amount of damage. A small defect may need repair or replacement, while a heavily weakened tooth may need a crown or root canal treatment if decay has reached the nerve.
How can you reduce the risk?
Reduce risk with fluoride toothpaste, interdental cleaning, professional checks, limited sugar frequency and early assessment of rough or leaking filling edges.
Practical advice: A filling should be treated as a repair that needs maintenance, not as a permanent shield against future decay.
Frequently asked questions
Can decay under a filling hurt?
Sometimes, but not always. Decay under fillings can be silent until it becomes deep.
Can X-rays show decay around fillings?
X-rays can help detect decay between teeth and under some restorations, but clinical examination is also needed.
Does recurrent decay mean the dentist did something wrong?
Not necessarily. Decay can return because of leakage, time, plaque, diet, dry mouth or high decay risk.
Can the filling simply be replaced?
Often yes, if enough healthy tooth remains. Larger damage may need a crown or other treatment.
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Disclaimer
This article provides general information from Gloss & Floss Dental Care® in Stockholm. It does not replace dental examination, X-ray diagnosis or individual restorative treatment planning.
