Does early tooth decay always need a filling?

No. As long as the decay only affects the outer enamel layer and shows as a white spot, it can often be stopped and partly re-hardened with fluoride, targeted cleaning and less sugar. A filling only becomes necessary once the surface has broken down and a genuine cavity has formed. This is why regular check-ups matter, because they make exactly this early intervention possible.

Does treating tooth decay hurt?

A small filling in the enamel is often possible without anaesthetic and is barely felt. If the decay reaches deeper into the dentine or towards the nerve, we numb the tooth locally so that the treatment itself is not painful. A mild ache once the anaesthetic wears off is possible, but usually settles quickly.

Can tooth decay heal on its own?

Only at the very first stage. A white spot in the enamel is demineralised but not yet broken down, and can re-harden through fluoride and good care. Once the surface has broken down or the decay reaches the softer dentine, it no longer heals on its own and has to be treated.

Why treat decay in milk teeth if they fall out anyway?

Because milk teeth have important jobs until the permanent teeth come through. They hold the space for the teeth that follow, are needed for chewing and speaking, and can cause pain or inflammation if decay reaches deep. Untreated decay in a milk tooth can also damage the permanent tooth developing beneath it.

How can I best prevent tooth decay?

With the combination of brushing twice a day with fluoride toothpaste, cleaning between the teeth daily and being mindful with sugar, especially how often you have sugary snacks and drinks. In addition, professional dental hygiene removes deposits where the toothbrush cannot reach. Regular check-ups round out your prevention.

Treating tooth decay. How cavities form and what really helps.

Tooth decay develops gradually and usually causes no pain early on. We explain how a cavity forms, how we detect it and which treatment is right depending on the stage.

Key takeaway

Tooth decay is the gradual dissolving of tooth substance by acids that bacteria produce from sugar. At the earliest stage it can often still be stopped without drilling, whereas a genuine cavity has to be filled. The earlier we detect decay, the smaller the treatment.

Written by Dr. Fredrik Nord 31 May 2026 8 min read

What tooth decay is

Tooth decay, also called caries or simply a cavity, is one of the most common chronic conditions there is. It does not appear from one day to the next, but develops gradually over weeks and months. At its core, decay is a loss of minerals: the hard tooth substance is dissolved bit by bit.

The cause lies with bacteria in dental plaque. These bacteria metabolise sugar and other carbohydrates from food and produce acids in the process. The acids dissolve minerals out of the enamel, a process known as demineralisation. As long as saliva and fluoride re-harden the enamel in between, this stays in balance. When that balance tips, for example through frequent sugar intake or patchy care, the loss of minerals wins out and decay sets in.

The stages of tooth decay

Decay develops in clear stages. The earlier it is detected, the smaller the treatment required:

Initial lesion (white spot). The enamel is superficially demineralised and shows as a dull, white spot. The surface is still intact. At this stage decay is often still reversible.
Enamel caries. The demineralisation progresses, the surface breaks down and a small cavity forms in the enamel. By this point at the latest, treatment is needed.
Dentine caries. The decay reaches the softer dentine beneath the enamel and spreads more quickly there. Sensitivity to sweet, cold or hot often begins now.
Pulp involvement. If the decay reaches the pulp (the soft core with nerve and blood vessels), it can cause persistent, often throbbing pain. A root canal is usually needed at this point.

How we detect tooth decay

The tricky part is that decay usually causes no pain early on. Those affected rarely notice the first stages themselves. This is precisely why decay is most often found at a regular check-up, before it causes any symptoms.

Detection includes:

Visual examination of discolouration, white spots and broken-down areas.
X-rays, which reveal decay between the teeth and beneath the enamel, where the eye cannot see it.
Modern aids such as laser-fluorescence devices, which can pick up early decay in places that are hard to see.

This way decay can often be detected while the treatment is still small.

How we treat it, by stage

Treatment depends on how far the decay has progressed:

Early lesion (white spot). Here we treat without drilling. The focus is on fluoride for remineralisation, improved home care and being mindful with sugar. An accompanying dental hygiene removes the deposits under which decay forms.
Genuine cavity. Once the surface has broken down, we remove the decayed substance and restore the tooth with a tooth-coloured composite filling, placed and hardened directly in the mouth.
Larger defect. If too much tooth substance is lost, a direct filling no longer holds reliably. A laboratory-made inlay or crown then comes into question. How the restorations differ is covered in our comparison of composite and inlay.
Decay into the pulp. If the nerve is affected or already inflamed, the tooth can often be saved with a root canal.
Tooth that can no longer be saved. If the tooth is too badly destroyed, the last step is removal (extraction). We then discuss closing the gap separately.

What to expect during a filling

For a filling, we numb the tooth locally where needed, so the treatment is not painful. We then remove the decayed substance and clean the area. The tooth is kept dry, the composite is placed in layers, hardened with light and finally shaped and polished so that it feels natural when you bite down. A small filling is often completed in a single appointment.

After the treatment the tooth may be sensitive to cold or hot for a few days, especially with deeper fillings. This usually settles on its own. While the anaesthetic is still working, wait before eating until the feeling has returned. If the tooth stays sensitive for longer or your bite feels noticeably different, get in touch with us.

Prevention is the best protection

In most cases tooth decay can be prevented effectively. What matters is the interplay of daily care and regular check-ups:

Brush twice a day with fluoride toothpaste. Fluoride hardens the enamel and makes it more resistant to acid.
Clean between the teeth daily with interdental brushes or floss, because decay forms particularly often there.
Be mindful with sugar, above all with frequency. It is not the amount alone but how often a day the teeth come into contact with sugar and acid that matters most.
Regular dental hygiene, which removes deposits and tartar where the toothbrush cannot reach.
Regular check-ups as part of prevention, so that decay can be treated early and with little effort.

Tooth decay in children

Milk teeth get decay too, and it should be taken seriously. Milk teeth hold the space for the permanent teeth, are important for chewing and speaking, and can hurt when decay reaches deep. Untreated decay in a milk tooth can also affect the permanent tooth growing beneath it. So the principle holds: milk teeth matter, and decay in them is treated just as it is in permanent teeth.

What treating tooth decay costs

The cost depends on the effort involved and the type of restoration, and in Switzerland it is calculated according to the SSO tariff. Before any larger treatment, you receive a written cost estimate from us, so you have clarity for planning. Note that basic insurance generally does not cover treating tooth decay. If you are unsure, book an appointment. We take a look at your teeth and discuss the right steps with you.