Tooth Decay (Cavities): Causes, Stages and Treatment at Each Stage

Tooth decay (also called dental caries or a cavity) happens when acid produced by plaque bacteria gradually breaks down the hard outer layer of a tooth. It usually starts as a small white or brown spot on the enamel, long before a hole is visible, and the same disease process is what eventually leads to a cavity, a toothache or, in the late stages, an abscess. Because decay does not always cause pain in its early stages, it is often first noticed at a routine check-up or on an X-ray rather than by the person themselves. What matters most is which stage the decay has reached, because that decides whether fluoride, a filling, an inlay or onlay, root canal treatment, or extraction is the right next step.

Tooth decay is one of the most common dental problems, and it develops gradually rather than overnight. Frequent sugary or acidic food and drink, a dry mouth, and areas that are hard to keep clean (such as around old fillings or exposed root surfaces) all increase the risk. Early decay, limited to a white spot on the enamel, can sometimes be stopped or even reversed with fluoride and better hygiene, without any drilling. Once a cavity has formed, it does not heal on its own, and the treatment needed becomes more involved the deeper the decay has spread.

Plaque is a soft, sticky film of bacteria that forms on teeth throughout the day. When these bacteria break down sugars from food and drink, they produce acid, and repeated acid attacks gradually dissolve minerals out of the enamel, a process called demineralisation. In its earliest form this shows up as a white spot, with the enamel surface still intact. If the acid attacks continue, the weakened enamel eventually breaks down into a cavity, and the decay can then spread more quickly through the softer dentine underneath, which is more sensitive to hot, cold and sweet stimuli than enamel. Left untreated, decay can reach the pulp (the nerve and blood vessels at the centre of the tooth), causing pain and inflammation, and can eventually lead to an abscess at the root tip. Each of these stages tends to call for a different treatment, which is why an examination and, where needed, an X-ray are used to confirm exactly how far the decay has progressed before any treatment is planned.

Tooth decay does not always cause noticeable symptoms, especially in its earlier stages, which is one reason regular check-ups and X-rays matter:

If you notice any of these signs, a free online consultation is a simple way to get an initial view — send a photo or an X-ray if you have one, and our dentists reply with an assessment before you travel.

Tooth decay develops from a combination of bacteria, sugar and time, but several factors make it more likely:

Several of these factors can act together — for example, a dry mouth combined with frequent sugary drinks tends to accelerate decay faster than either factor alone.

A white spot without any sensitivity can usually wait for your next routine check-up, since it may be managed with fluoride and better hygiene rather than a filling. See a dentist sooner if you notice a visible hole, ongoing sensitivity to hot, cold or sweet food, or pain when biting down, since these can point to decay that has already reached the dentine or deeper. Swelling of the gum, a persistent throbbing pain, or a fever should be assessed urgently, as these can be signs that an infection has spread from the tooth into the surrounding tissue.

Diagnosis starts with a clinical examination, where the dentist looks at each tooth surface under good light and checks for soft or discoloured areas with a probe. Because decay between teeth or underneath an existing filling is not always visible to the eye, a bitewing or panoramic X-ray is often used to confirm how far it has spread and whether it has reached the dentine, the pulp or the root tip — read more about our panoramic X-ray. Vitality tests, which check how the nerve inside the tooth responds, may also be used where decay is suspected to have reached the pulp.

Our process starts with a free online consultation: send clear photos of the tooth and, if you have one, an existing X-ray, and our dentists, led by Dt. Vijdan Aslanoğlu, reply with an initial assessment before you book anything.

An early white spot, without a cavity, can sometimes be stopped or even reversed with fluoride and improved hygiene, so it does not always need drilling straight away. Once a cavity has formed, however, it does not heal on its own, and leaving it tends to make the eventual treatment more involved rather than avoiding it altogether. Untreated decay generally spreads deeper into the tooth over time, moving from a small filling towards an inlay, onlay or crown, and eventually towards root canal treatment or, in advanced cases, extraction. Assessing decay early keeps more of the simpler, less invasive options open.

The right treatment for tooth decay depends mainly on how far it has progressed:

A dentist confirms which of these applies to your tooth after an examination and, where needed, an X-ray.

Preventing new decay and treating an existing cavity both sit within general dentistry, alongside the X-rays used to assess it.

Tooth decay progresses through recognisable stages, and the treatment that is likely to be considered changes at each one. This is a simplified illustration — your dentist confirms the actual stage with an examination and, where needed, an X-ray.

As a general pattern, whether there is an actual hole in the tooth, whether the nerve has been affected, and whether the tooth can still be restored all guide which treatment is likely to be considered. The illustration below sets out this decision path in a simplified way; your dentist confirms the right treatment for your tooth after an examination and, where needed, an X-ray.

Two decisions come up often as decay is assessed: whether a filling or an inlay/onlay suits a cavity better, and whether a badly decayed tooth is better saved with root canal treatment or removed and replaced. Both decisions depend on how much healthy tooth structure remains, which your dentist checks at your examination.

At Er Dental Clinic, tooth decay is assessed by Dt. Vijdan Aslanoğlu and our general dentistry team. The process starts with a free online consultation: send a photo of the tooth, and an existing X-ray if you have one, and you receive an initial assessment before travelling. At the clinic, a clinical examination and, where needed, a panoramic or other X-ray confirm exactly how far the decay has progressed, and the proposed treatment, materials and cost are set out in writing before anything begins.

The clinic holds an International Health Tourism Authorization Certificate issued by the Republic of Türkiye Ministry of Health (certificate no. ST-6264), which you can verify on the e-Devlet document verification service at turkiye.gov.tr/saglik-bakanligi-ebys. You can also contact our clinic in Istanbul directly with any questions.

Send us a photo of the tooth, or an X-ray if you have one, on WhatsApp or through a free online consultation. Our dentists review it and reply with an initial assessment of the stage the decay has reached and the treatment options that may apply, so you can decide with confidence before booking anything.