Untreated tooth decay: how long can you wait if the tooth does not hurt?

Key points in brief

• How long you can wait depends mainly on the cavity's depth. Shallow cavities usually leave the most time, and the nearer the pulp, the tooth's nerve-filled core, the less.
• No pain does not mean that untreated tooth decay is standing still. Its pace is strongly affected by how often during the day you eat or drink something sugary.
• Agree the date with the dentist who examined the tooth and the X-ray. Until the appointment, cut down on sugary snacks between meals and brush your teeth with fluoride toothpaste.
• Pain that comes on by itself or wakes you at night, swelling or fever need a dentist the same day, and pain after something hot within a few days.
• How fast your decay progresses cannot be predicted to the month, so ask for an earlier appointment whenever the tooth reacts in a new way to cold or sweet things.

Does tooth decay hurt as the cavity grows?

Tooth decay usually stays painless for a long time, because it starts in the enamel. This is the hard outer layer of the tooth, and it has no nerves. Beneath it lies the dentine, and at the very centre of the tooth is the pulp, the living tissue that contains nerves and blood vessels. Once decay reaches the dentine, the tooth may react briefly to cold or sweet things, but in many people it does not hurt even then.

Between the teeth, decay starts just below the point where neighbouring teeth touch. From the outside it can be almost invisible, even though it has already spread more widely inside, which is why the dentist checks these areas on an X-ray. Untreated tooth decay can reach deep into the dentine before anything hurts, so the absence of pain does not tell you how much time is left.

If treatment has already started and the tooth has a temporary filling, do not postpone the next appointment without talking to your dentist. If you are not sure whether a dark spot on a tooth is decay at all, an examination will settle it. If you are putting off treatment because you are afraid it will hurt, find out whether drilling a tooth hurts and when you need an anaesthetic.

What to ask your dentist before you postpone treatment

If you want to fit the treatment around work or a trip, talk it over with the dentist who found the cavity. The simplest way is to ask straight away in the surgery, but you can also do it later, for example by phone.

Ask how deep the cavity goes: in the enamel, in the dentine or close to the pulp. Find out what the X-ray shows, what timing for treatment is reasonable at that depth and what will change if you wait a few weeks. Ask, too, which symptoms should make you phone sooner and what you can do at home until the appointment. Write the answers down together with the appointment date, because they are easy to forget.

What happens to an untreated cavity over the following months

Untreated tooth decay moves through the layers of the tooth one after another, and with each layer there is less time to decide. Pain need not appear at any of these stages. The pace varies a great deal from person to person, so none of the descriptions below marks a point up to which you can simply wait.

A shallow cavity, in the enamel or just beneath it

• What happens to the cavity: an early change in the enamel usually deepens slowly, often over years, and some of these changes do not deepen at all. The dentist usually suggests a filling when the area cannot be cleaned well. A cavity in a place like that is more likely to deepen.
• What shortens the wait: new sensitivity to cold or sweet things in that spot, a chipped wall of the tooth, new cavities in the past year.
• How treatment changes: a small filling is usually enough, and at a check-up the dentist assesses when early tooth decay can be stopped without drilling. This is where you have the most freedom in choosing a date.

A cavity deeper in the dentine

• What happens to the cavity: once decay has passed through the enamel, it usually speeds up, because dentine is softer than enamel and decay spreads through it more easily. Below the surface the cavity can be larger than it looks. In any one person it is impossible to predict how quickly such a cavity will reach the pulp, so it is worth setting a treatment date straight away, even if it falls a few weeks later.
• What shortens the wait: brief pain after something cold or sweet, food that keeps getting stuck in the same place, a chipped edge of the tooth.
• How treatment changes: a filling is usually still enough, but it is larger. There is less time to decide than with a shallow cavity.

A deep cavity, close to the pulp

• What happens to the cavity: only a thin layer of dentine is left over the pulp, and inflammation builds up in the pulp itself, often still without pain.
• What shortens the wait: pain after something cold that lasts longer than a dozen or so seconds, pain when biting.
• How treatment changes: the risk grows that a filling alone will no longer be enough. Here the time frame is more a matter of weeks, and the dentist sets it after assessing the depth.

Severe inflammation of the pulp, or a pulp that is dying

• What happens to the cavity: the pulp is severely inflamed or is starting to die.
• What shortens the wait: this is where waiting ends. The signals are pain that comes on by itself or wakes you at night, pain after something hot, pain after something cold that lasts for minutes, a small pimple on the gum or swelling of the gum.
• How treatment changes: a filling alone is usually not enough. Sometimes part of the living pulp can be preserved, while a pimple on the gum or swelling usually means that the pulp has died and root canal treatment is needed.

If you have pain that comes on by itself or wakes you at night, swelling of the gum or face, or a fever, see the nearest available dentist or an emergency dental service on the day the symptoms appear. Plan the examination and further treatment at the clinic for the following days.

Pain after something hot, pain after something cold that lasts longer than a dozen or so seconds, pain when biting, or a pimple on the gum (a dental sinus tract) without swelling need an appointment within a few days, not at your next check-up. When a tooth reacts to heat and cold brings relief, the inflammation of the pulp is usually more advanced.

Shortness of breath, difficulty swallowing or breathing, swelling that spreads to the neck or under the eye, or a high fever with feeling generally unwell are reasons to go to a hospital emergency department (A&E) or call 112.

How fast does tooth decay progress, and what affects the pace?

Untreated tooth decay usually progresses slowly, but its pace varies widely between people and can change in the same person. Roughly 2 in 10 changes in the enamel had reached the dentine or been filled within about 10 years, between the ages of 17 and 27. In adults at high risk of decay, roughly one in three early cavities between the teeth became deeper over about a year and a half of follow-up.

The deeper and more active a cavity is, the more often it progresses. The dentist judges activity by how the affected area looks and how hard it feels: an active one is usually matt and soft.

The pace also depends heavily on how often sugar is in your mouth during the day. A clearly reduced flow of saliva - caused, for example, by medicines or illness - also favours decay. Regular brushing with fluoride toothpaste slows decay down.

It is not possible to predict to the month how quickly decay will progress in a particular person. An important clue is whether new cavities have appeared in recent years and whether changes seen on successive X-rays have been getting deeper. That is why the dentist also bases the treatment date and the interval between check-ups on your risk of decay.

How untreated tooth decay changes the treatment a tooth needs

The deeper the decay reaches, the larger the filling and the greater the risk that treatment will have to involve the pulp. Dentists call a cavity close to the pulp a deep cavity: it reaches the innermost part of the dentine, but a layer of hard dentine still remains between the decay and the pulp.

With a deep cavity, the dentist may deliberately leave a thin layer of softened dentine over the pulp and close it with a well-sealed filling, so as not to expose the pulp. European guidelines suggest this, but it is not yet known whether it protects the pulp better than removing all of the decay. During the procedure, when the dentist can see the floor of the cavity, they judge how much decay to remove.

A filling alone stops being enough when the pulp becomes exposed or is severely inflamed. The dentist then protects it with a special material, removes part of it, or carries out root canal treatment. Which procedure is used depends on the condition of the pulp. The dentist tells reversible from irreversible pulpitis, meaning inflammation of the pulp, partly by how long the pain after cold lasts.

Untreated tooth decay can eventually lead to the death of the pulp and infection around the root of the tooth. Root canal treatment is then usually needed, and if the tooth can no longer be restored, it has to be extracted.

A deep cavity also weakens the walls of the tooth. The dentist checks how much healthy tooth tissue is left, because that determines whether a filling, an inlay or a crown is the better choice for a large cavity.

What to do if treatment has to be put off for a few weeks

If treatment has to be postponed, tell the dentist, not just reception, because the dentist is the one who knows how deep the cavity is. With a shallow cavity, a few weeks usually make little difference. With a deep one, the dentist may suggest an earlier date. It is best to book your treatment of tooth decay straight away.

Until the appointment, cut down on sugary snacks and sweetened drinks between meals. Brush twice a day with fluoride toothpaste and clean between your teeth every day with floss or an interdental brush. This will not replace treatment of a cavity in the dentine, but untreated tooth decay may then deepen more slowly. If a wall of the tooth is thin or has already chipped, do not bite on anything hard with that tooth.

If during this time the tooth starts reacting differently from before - to cold, to sweet things or when you bite - do not wait for the booked date. Brief, new sensitivity is a reason to phone and bring the appointment forward. Pain after something sweet at the site of the cavity usually means that the decay has reached the dentine.

Pain after something hot, or pain after something cold that lasts longer than a dozen or so seconds, means an appointment within a few days, and pain that comes on by itself or wakes you at night means an appointment on the day the symptoms appear. If the tooth hurt for several days and then stopped, phone as well, because the pain can also go away when the pulp is dying.

How long can a cavity go untreated, and how do you set a date for treatment?

How long you can wait is determined above all by the depth of the cavity, so book the date straight away and move it only after talking to your dentist. If the tooth starts reacting differently from before while you wait for treatment, phone and bring the appointment forward, because this is a sign that untreated tooth decay may have gone deeper.

With pain that comes on by itself or wakes you at night, or with swelling or a fever, see a dentist the same day. Shortness of breath, difficulty swallowing or breathing, swelling that spreads to the neck or under the eye, or a high fever with feeling generally unwell are reasons to go to a hospital emergency department (A&E) or call 112.

Frequently asked questions

Can a cavity that does not hurt stop without treatment?

A cavity that has broken through the enamel into the dentine rarely stops, and usually only when it can be cleaned thoroughly. Its floor then becomes hard and shiny. An early change in the enamel often stops when cleaning improves and sugar is cut down, and at a check-up the dentist assesses at which of the stages of tooth decay monitoring is enough.

Can decay spread to the neighbouring tooth?

Decay does not pass from tooth to tooth like an infection, but when there is a cavity between two teeth, the neighbouring tooth often has one too. The same plaque between the teeth acts on both surfaces where they touch, and food gets trapped more easily next to a cavity. That is why the dentist looks at both teeth on the X-ray, and after the filling it is important to clean that space every day.

Does an X-ray show how deep a cavity is?

An X-ray often shows cavities between the teeth that cannot be seen with a mirror, but it gives their depth only approximately. During treatment, a cavity usually turns out to be slightly deeper than it looked on the X-ray. Only after removing the decay can the dentist make a final judgement of how much healthy dentine is left over the pulp, which is why the treatment plan may change at that point.

Does decay under an old filling develop in the same way as in a healthy tooth?

Decay at the edge of an old filling develops much as it does in an untreated tooth: it also usually stays painless for a long time and can be deeper than it looks from the outside. The dentist examines the edge and looks at the X-ray, and then assesses when decay under an old filling means that the filling needs replacing.

Do the first brief twinges mean that treatment can no longer wait?

Brief pain after something cold that fades within a dozen or so seconds usually means that the decay has reached the dentine and is irritating the pulp. It is a reason to bring treatment forward, but it does not usually call for a same-day appointment and need not mean root canal treatment. Pain that lasts longer needs an appointment within a few days, and pain that comes on by itself or wakes you at night needs one on the day the symptoms appear.

How long after treatment of a deep cavity does the dentist check whether the pulp has settled?

Usually after a few months and again after a year, the dentist checks whether the pulp has settled, based on your symptoms, a cold test and an X-ray. For a few days after the filling the tooth may be sensitive to cold, but pain that gets worse, comes on by itself or wakes you at night needs an appointment on the day the symptoms appear.

Read more:

• Aesthetic and Restorative Dentistry in Warsaw
• A tooth that reacts to heat, not to cold - why that is the worse symptom
• Secondary caries: when an old filling really needs replacing, and when it can be left alone
• Comprehensive dental review: What does it contain and why is it crucial for health?
• Root canal treatment step by step: How long does it take, what does it look like and what to expect?

Content and liability disclaimer

This article is informational and educational in nature and does not constitute medical advice, a diagnosis or a therapeutic recommendation — it does not replace a consultation with a specialist. If you are experiencing symptoms, have doubts or are facing a decision about treatment, consult a dentist. The methods described and the data cited are general in nature. The results of scientific studies relate to populations, not to an individual patient. The course and outcome of therapy depend on the individual clinical situation and may vary between patients. No information contained in this article constitutes a guarantee of result. The content has been prepared with due care, based on publicly available medical knowledge and the scientific publications indicated in the Sources section. We do not advise taking or refraining from any health-related action solely on the basis of the content of this article, without prior consultation with a doctor.

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