A cavity between teeth, known as interproximal decay, forms in the tight contact point where a toothbrush cannot reach and only floss or interdental cleaning can. These cavities are common because plaque and food sit undisturbed between teeth, and they often cause no symptoms until they are quite advanced. That is why dentists rely on a bitewing X ray to catch them early, and why cleaning between your teeth every day matters so much.
Key takeaways
- Interproximal decay forms between teeth, where brushing alone does not clean.
- Early cavities between teeth usually cause no pain, so they are easy to miss without an X ray.
- Daily flossing or interdental brushing is the single best way to prevent them.
- Very early decay may be halted, but a formed cavity needs a filling.
- Regular check ups and bitewing X rays catch these cavities before they reach the nerve.
Why cavities form between teeth
Where two teeth touch, there is a sheltered contact point that a toothbrush bristle simply cannot enter. Plaque, the sticky film of bacteria, collects there along with tiny food particles. The bacteria turn sugars into acid, and that acid slowly dissolves the enamel. Because the spot is hidden and protected, decay can progress quietly. Tight contacts, crowded teeth, and skipping flossing all raise the risk. Our guide on plaque versus tartar explains how this film hardens if it is not removed.
Why you may not feel it
Enamel has no nerves, so a cavity that is still in the outer layers causes no pain. Symptoms like sensitivity to sweet, hot, or cold, or an ache, tend to appear only once decay reaches the softer dentine or nears the nerve. By then a simple filling may have become a larger repair. This silent early stage is exactly why routine examinations matter.
How dentists find decay between teeth
Because the contact point is hidden from view, dentists use a bitewing X ray, which shows the areas between the back teeth clearly. Decay appears as a shadow spreading in from the surface. Catching it on an X ray while it is shallow means it can be treated conservatively, and sometimes very early decay in the outer enamel can be remineralised rather than filled. Our guide on reversing early decay explains when that is possible.
How it is treated
| Stage | Typical approach |
|---|---|
| Very early, outer enamel | Fluoride and improved cleaning may halt or reverse it |
| Cavity into dentine | A filling to clean out decay and restore the tooth |
| Deep, near the nerve | A larger filling, or root canal if the nerve is affected |
Once a true cavity has formed, it will not heal on its own and needs a filling. Our guide on getting a filling walks through what that involves.
How to prevent cavities between teeth
The prevention is simple and effective. Clean between your teeth once a day with floss or interdental brushes, brush twice a day with a fluoride toothpaste, and limit frequent sugary snacks and drinks. Our guide on how to floss properly shows the technique that actually reaches the contact point. Keeping up regular check ups lets your dentist catch anything early.
Frequently asked questions
Can a cavity between teeth heal itself?
Only very early decay limited to the outer enamel may be remineralised. Once a cavity has formed, it needs a filling.
How do I know if I have one?
Often you will not feel it early on. A bitewing X ray at a check up is the reliable way to find decay between teeth.
Does flossing really prevent them?
Yes. Flossing or interdental cleaning removes the plaque from the contact point that brushing cannot reach, which is where these cavities form.
Will a cavity between teeth need a bigger filling?
Not if caught early. The longer it goes unnoticed, the larger the repair tends to be.
Can both touching teeth get a cavity?
Yes. Because plaque sits against both surfaces at the contact point, decay can develop on either or both teeth.
Due for a check up?
A simple examination and bitewing X rays can catch decay between teeth long before it causes pain. The team at Lumi Dental can check and advise on prevention. See current options on our offers page.
This article is general information and is not a substitute for personal dental advice.
