Can you get a cavity between your teeth? Signs to watch

A cavity does not have to be visible, or painful, to exist. Decay between teeth is one of the most common places it starts precisely because it hides where you cannot see or feel it, and where a toothbrush cannot physically reach to prevent it.

Why this spot is so vulnerable

Where two teeth touch, there is a small contact point that traps plaque and trapped food debris in a space a toothbrush bristle simply cannot physically access, no matter the brushing technique or how long you spend. Bacteria in that trapped plaque produce acid that slowly demineralises the enamel on both facing tooth surfaces, starting a cavity that stays hidden from view because it is literally between the teeth rather than on a visible surface.

Why you cannot see or feel it yourself

Unlike decay on a visible chewing or front surface, which can show up as a dark spot or a textural change you might notice, interdental decay forms on surfaces facing each other, invisible without separating the teeth or using specific imaging. It is also commonly painless in its early stages, since the decay has to progress through the enamel and partway into the dentin layer before reaching nerve tissue closely enough to cause sensitivity. Our guide to signs you have a cavity covers the more general symptom picture, which often does not apply to this specific type until it is advanced.

How it is actually found

Bitewing X-rays, a specific type of dental X-ray angled to capture the back teeth biting together, are the standard way dentists check for interdental decay, which is why these are recommended periodically, typically every one to two years depending on your individual risk, even for patients with no symptoms and a clean-looking smile. Catching decay at this stage, while it is still small and confined to enamel, usually means a simple, smaller filling rather than a more involved procedure later.

Why flossing matters here specifically

Floss, interdental brushes, or a water flosser are the only tools that physically reach the contact area between teeth, which is exactly the space this type of cavity forms in. Our comparison of water flosser vs dental floss covers which suits different situations, but the key point either way is that brushing alone, however thorough, leaves this area systematically under-cleaned.

Treatment once found

Caught early, a straightforward filling restores the tooth, with the material carefully shaped to recreate a normal, snug contact with the neighbouring tooth so food does not simply get trapped there again. Left longer, deeper decay may need a larger filling or, if it reaches the nerve, root canal treatment. This is the practical case for routine check-ups and X-rays even when your teeth feel completely fine.

Sources & further reading

American Dental Association (MouthHealthy) · NHS, Dental Health · NIDCR, US National Institute of Dental & Craniofacial Research · Indian Dental Association