Pain & Sensitivity

My tooth hurts but the X-ray shows nothing: what could it be?

A clear X-ray may not mean there is no problem, only that the X-ray cannot answer that question

You point to the pain with your finger, and the dentist looks at the X-ray and says they cannot see anything. This happens very often, and it can mean two different things. The first is that the problem really is in the tooth but is too early or too fine for a plain X-ray to see: a hairline crack, or inflammation of the nerve that has not yet shown up in the bone. The second is that the pain is felt in the tooth but comes from somewhere else: the sinus, the chewing muscles, a nerve or the heart. What tells them apart is not the image but the tests done on the tooth.

Short answer

When a tooth keeps hurting and the X-ray is clear, the main causes inside the tooth are a hairline crack and early inflammation of the nerve that has not yet shown up in the bone; both are often invisible on a plain X-ray. Causes outside the tooth are sinusitis, pain in the chewing muscles, pain from a nerve and, rarely, the heart. The distinction is made by a cold test, a bite test and tapping on the tooth. If no single tooth reproduces the pain, no irreversible procedure should be started.

The limit of a plain X-ray: It often misses infection at the root tip in the early stage
A crack: Usually invisible on an X-ray, found with a bite test
What tells them apart: A cold test, a bite test, tapping on the tooth and the accompanying symptoms
The basic rule: No root canal treatment or extraction until a tooth reproduces the pain

Medically reviewed by Bilge Ilgın, Dentist · ImplantologyLast reviewed 2026-09-25

What an X-ray can see, and what it cannot

A dental X-ray shows the shadow of hard tissue: enamel, dentine and bone. The pulp, the nerve and blood vessel tissue inside the tooth, is soft tissue; when it becomes inflamed it leaves no change on an X-ray. What is seen on an X-ray is not the inflammation itself but the dark shadow it leaves once it has started to break down the bone at the root tip. That shadow takes time to form. So in the first days of pain the X-ray can come back clear, because there is not yet any change in the bone to see.

There are studies measuring how even inflammation that has already reached the bone can be missed on a plain X-ray. In a study published in the International Endodontic Journal, 86 roots in cadaver jaws were first imaged and then examined under the microscope. Infection at the root tip was picked up by a digital X-ray taken from a single angle in 27 per cent of cases, with additional angled views in 38 per cent, and by cone beam CT in 89 per cent. In another study, from Brazil, looking at 1,508 teeth of patients with root canal infections, sensitivity with CT as the reference was 55 per cent for periapical X-rays and 28 per cent for panoramic X-rays, and the authors wrote that the conventional methods only identified the inflammation correctly at an advanced stage.

These figures also show an important distinction: the small film taken from inside the mouth of a single tooth (a periapical X-ray) and the panoramic X-ray showing the whole mouth are not the same thing. A panoramic gives a wide area in one image but is weaker on fine detail such as the root tip. When you are told "there is nothing on the X-ray", it is worth asking which X-ray was taken. A periapical view aimed at the painful tooth, and if needed a second view from a different angle, can show what the panoramic missed.

Because cone beam CT (CBCT) shows the tooth and its surroundings in three dimensions, it is clearly more sensitive for infection at the root tip. But it is not the first step for every pain: it involves more radiation, metal fillings, crowns and root fillings create streaks of glare on the image, and it can still miss fine cracks. The limits of CT with cracks and fractures are explained in detail on our cracked tooth page. CT usually comes up when the clinical tests point to a tooth but the plain X-ray stays silent.

The first cause inside the tooth for pain that does not show on an X-ray is a crack. In a registry study in the USA involving 209 practices and following 2,858 patients with a visible crack, only 2 per cent of the cracks could also be made out on an X-ray. In the same study the commonest complaint was sensitivity to cold, while pain on biting was more strongly linked with the crack. The dentist looks for it with a bite test that loads the cusps of the tooth one by one, a strong light shone through the tooth, and dye. For other causes of pain that comes on when chewing, see the page on a tooth that hurts when chewing.

The second cause inside the tooth is early inflammation of the pulp, known as pulpitis. Cleveland Clinic separates two stages like this: in reversible pulpitis, sensitivity brought on by cold or sweet things passes quickly, there is no sensitivity to heat, and tapping on the tooth does not hurt. In irreversible pulpitis, sensitivity to hot, cold or sweet things lasts longer than a few seconds, there may be throbbing or a dull ache, and tapping on the tooth hurts. In both stages the X-ray can look normal. That is why the decision is made not from the image but by looking at how long the cold lasts.

Then there is toothache whose source is not in the tooth. A systematic review in the Journal of Oral Rehabilitation divides toothache felt when there is no visible cause in the tooth or gum into eight groups: muscle pain referred to the tooth, pain from a nerve, pain of unknown cause, migraine-like pain from the blood vessels, sinus pain referred to the tooth, heart pain referred to the tooth, pain of psychosocial origin and pain linked to other diseases. The review's conclusion is a single sentence: unnecessary dental treatment should be avoided.

A meta-analysis in the Journal of Endodontics shows why this warning matters. In studies looking at pain lasting more than six months after root canal treatment, pain continuing with no sign of disease in the tooth was seen in about 3.4 per cent of teeth. More striking is this: in 56 per cent of the cases of persistent pain (44 of 78 cases), the source was thought to be outside the tooth. The authors write that about half of the pain persisting after root canal treatment may fall into this group, and that in these cases treatment aimed at the tooth is not expected to resolve the pain.

Which signs point to the tooth, and which to another source

The first list shows the signs that suggest the problem is in the tooth even if the X-ray is clear. The second list shows that the source may be elsewhere, or that waiting is not the right thing to do.

When it fits

If a short, sharp pain comes the moment you bite and let goThis is the best-known behaviour of a cracked tooth. The pain often comes on a particular cusp when you bite at a particular angle; the dentist looks for that spot with a bite test.
If the pain carries on after the cold water has goneCleveland Clinic counts sensitivity that lasts longer than a few seconds as a sign of irreversible pulpitis. A brief twinge that passes quickly suggests an earlier stage that can still recover.
If you can point to the pain in a single tooth with your fingerPain from a tooth usually settles on a single tooth and is reproduced by a test on that tooth. This is a strong reason to focus on the tooth, even if the X-ray is clear.
If that tooth recently had a deep filling or a crownDeep fillings can strain the pulp, and a filling left too high can hurt on biting. Both are common pictures that cause pain without showing anything on an X-ray.

When it doesn't

If several upper back teeth on the same side hurt at onceEspecially if it gets worse when you bend forward and comes with a blocked nose, the sinus is suspected. The NHS lists toothache among the symptoms of sinusitis and writes that sinusitis usually clears up on its own within 4 weeks.
If the pain is there in the morning and your jaw and temple are tired tooPain referred to the tooth from the chewing muscles is linked to clenching and grinding. In this picture, pressing on the muscle can reproduce the toothache, while the tests done on the tooth do not.
If the pain comes on when you walk or climb stairs and goes when you restThe NHS writes that angina pain can be felt outside the chest too, in the neck, shoulders, jaw or arms, and that it usually starts with exertion. If there is pressure or pain in the chest together with sweating, feeling sick, dizziness or shortness of breath, or if the pain does not go when you rest, call 112. Even if the pain comes and goes, see not your dentist but your GP or a cardiologist as soon as possible.
If attacks lasting seconds come like an electric shockThe NHS describes trigeminal neuralgia as sudden attacks felt like an electric shock in the jaw, teeth or gums, lasting from a few seconds to about 2 minutes; the attacks are often triggered by light touches such as washing the face, eating or brushing the teeth. If the dentist has ruled out a dental cause, the next port of call is your GP or neurology; no irreversible dental procedure should be started.

How the source is found, step by step

The sequence starts not with the image but with danger and tests. The aim is to prove where the pain comes from before any irreversible procedure is started.

1
Emergency signs first: stop and go to A&E
If toothache comes with swelling around the eye or in the neck, or swelling in the mouth or neck that is making it difficult to breathe, swallow or speak, the NHS says to go straight to A&E. If the pain comes on with exertion and there is pressure in the chest, sweating or shortness of breath, call 112. In these situations you do not wait for an X-ray or tests.
2
The story of the pain is heard
What starts the pain: cold, heat, biting, bending forward, walking? How long does it last: seconds or minutes? Does it wake you from sleep? Do other teeth on the same side, your jaw, temple or ear hurt? These questions often say more than the image.
3
The cold test
A cold cotton pellet is touched in turn to the suspect tooth and its neighbours. The dentist looks at three things: does the tooth feel it, is the pain the one you know, and how long does the pain last once the cold is taken away. Pain that lasts longer than a few seconds suggests the pulp is seriously inflamed, while no response at all suggests the nerve may have died.
4
The bite test and tapping on the tooth
The cusps are loaded one by one with a special device; a sharp pain on letting go points to a crack. Tapping lightly on the tooth shows whether the tissue around the root is inflamed. Cleveland Clinic counts pain on tapping among the signs of irreversible pulpitis.
5
The right X-ray, and CT if needed
If the panoramic is not enough, a periapical X-ray aimed at the painful tooth is taken, and if needed a second view from a different angle. If the tests clearly point to a tooth but the plain X-ray is silent, cone beam CT comes up. Even a clear CT does not completely rule out a crack.
6
Sources outside the tooth are looked for
If no tooth reproduces the pain, the chewing muscles are pressed, sinus symptoms are asked about, and depending on the character of the pain you are referred for assessment by ear, nose and throat, neurology or cardiology.
7
Monitoring if it is unclear
If the source has not become clear, waiting and repeating the tests a few days or weeks later is safer than rushing into root canal treatment or an extraction. As pulp inflammation progresses the tests give a clearer answer, and as the inflammation reaches the bone the X-ray starts to speak too.

What is done, depending on the source

There is no single right treatment; the route changes with the source that is found.

A cracked tooth

Depending on where the crack is and how deep it goes, holding the cusps of the tooth together with a crown or an onlay, and root canal treatment if the nerve is affected. Which cracks let the tooth be saved and which cost you the tooth is explained on the cracked tooth page.

Reversible pulpitis

Cleveland Clinic writes that at this stage cleaning out the cause, usually decay, and sealing the tooth with a filling is enough. The pulp is kept.

Irreversible pulpitis

An inflamed pulp does not recover; with root canal treatment the pulp is removed and the canals are cleaned. The decision is made from how long the cold test lasts and the finding on tapping; a clear X-ray does not change that decision.

Pain from the sinus

When the sinusitis is treated or clears on its own, the toothache fades too. The NHS writes that sinusitis usually clears within 4 weeks and that you should see a GP if it has not improved after 3 weeks of treating it yourself.

Pain from a muscle or a nerve

For chewing muscle pain, a night guard and reducing the load; for pain from a nerve, medicine started by a doctor; the NHS writes that the first choice for trigeminal neuralgia is carbamazepine, which is also used to treat epilepsy. In neither case does a procedure on the tooth resolve the pain.

Common mistakes in this situation

We are writing the points below so that you can ask the right questions whichever clinician you see.

Reading a clear X-ray as "there is nothing wrong with the tooth"

The measured figures are there: in one study, a single-angle digital X-ray picked up infection at the root tip in only 27 per cent of cases. If the test findings point to a tooth, a clear X-ray on its own does not clear that tooth.

Root canal treatment or extraction without testing

A procedure carried out without finding a tooth that reproduces the pain does not get rid of the pain if the source is elsewhere, and it cannot be undone. According to one meta-analysis, in about half of the pain persisting after root canal treatment the source may lie outside the tooth.

Thinking the problem is solved because the pain has gone

An inflamed pulp can die after a while; sensitivity to cold then disappears and the pain may ease. Cleveland Clinic writes that when the nerve dies the tooth can lose feeling to heat and cold but still hurt when tapped. The infection moves silently towards the root tip.

Focusing on the tooth pointed to and not testing its neighbours

With referred pain, people can feel the source in the wrong tooth, or even in the opposite jaw. That is why the test needs doing not only on the tooth complained about but on its neighbours and the opposite jaw too.

Getting by on antibiotics

Cleveland Clinic writes that antibiotics are not a treatment for pulpitis; what resolves this pain is removing the cause, or root canal treatment. Antibiotics belong to pictures with a spreading infection and a high temperature.

What to expect afterwards

The timings vary with the source that is found. The course below shows the paths most often seen.

Until the source is clear
For this period the NHS recommends ibuprofen or paracetamol, soft food, not chewing with the painful tooth, and avoiding very hot, very cold or sweet food. Noting what starts the pain and how long it lasts speeds up the next examination.
After a filling or a crown
In reversible pulpitis, once the cause has been cleaned out, the sensitivity usually decreases gradually. If it gets worse or turns into throbbing, the inflammation of the pulp may have progressed.
After root canal treatment
Tenderness on biting is expected in the first few days and eases on its own. With pain that is still there months later, the diagnosis should be reviewed.
If the source is not the tooth
The course of pain from the sinus, a muscle or a nerve depends on the treatment of that condition. Dental treatment does not shorten it.

Don't wait if

There is swelling around your eye or in your neck. In this picture the NHS says to go straight to A&E. Do not drive yourself to A&E.
It has become difficult to breathe, swallow or speak. If swelling in your mouth or neck is causing this, go to A&E immediately or call 112.
The pain comes on with exertion, with pressure in the chest or sweating. This behaviour suggests the heart. Call 112.
The pain lasts more than 2 days or does not go away with painkillers. The NHS advises seeing a dentist in this case; a high temperature, pain when you bite, red gums or a bad taste in your mouth are on the same list.

What determines the cost

We do not give a single figure here, because depending on the source the route may end with a filling or may go on to root canal treatment, a crown, or a referral that needs no dental treatment at all. These are the items that determine the scope:

The source of the pain: A crack, pulpitis, the sinus, a muscle or a nerve are entirely different jobs and the field of different clinicians.
The extent of imaging: A periapical X-ray is often enough; if the tests point to a tooth but nothing shows, CT is added.
The state of the pulp: At the reversible stage a filling may be enough; at the irreversible stage root canal treatment is needed, often with a crown on top.
How deep the crack goes: A crack confined to a cusp can be protected with a crown; a crack reaching into the root changes the plan completely.

Frequently asked questions

My tooth hurts but there is nothing on the X-ray. What could it be?

Inside the tooth, the two main causes are a hairline crack and early inflammation of the nerve that has not yet shown up in the bone. Outside the tooth, sinusitis, pain in the chewing muscles, pain from a nerve and, rarely, the heart. What tells them apart is not the X-ray but a cold test, a bite test and tapping on the tooth.

Does a crack show on an X-ray?

Usually not. In a registry study following 2,858 cracked teeth, only 2 per cent of the cracks could be made out on an X-ray. What is usually seen on an X-ray is not the crack itself but the bone loss it causes once it has progressed. The diagnosis is made with a bite test, a strong light and dye.

Will everything show if I have a CT scan?

No. Cone beam CT is clearly more sensitive than a plain X-ray for infection at the root tip; in one study it picked up the infection in 89 per cent of cases. But it can miss very fine cracks, and metal fillings and root fillings can spoil the image. A clear CT does not completely rule out a crack.

Is there a difference between a panoramic X-ray and an X-ray of a single tooth?

Yes. A panoramic shows the whole mouth in one image but is weak on detail; in a study of 1,508 teeth with CT as the reference, the rate of picking up infection at the root tip was 28 per cent for panoramic X-rays and 55 per cent for periapical X-rays of a single tooth. Asking for a separate view of the painful tooth is a fair question.

My tooth twinges when I drink cold water but the X-ray is clear. Do I need root canal treatment?

The decision depends on how long the twinge lasts. Cleveland Clinic links sensitivity that passes quickly with reversible pulpitis, and sensitivity lasting longer than a few seconds with irreversible pulpitis. At the reversible stage, cleaning out the cause and placing a filling is enough; root canal treatment is the treatment for the irreversible stage. A clear X-ray is possible at both stages.

I had root canal treatment but the pain has not gone. What should I do?

First ask for the diagnosis to be reviewed. In one meta-analysis, in 56 per cent of the cases of pain persisting after root canal treatment (44 of 78 cases), the source was thought to be outside the tooth. Before a second procedure on the same tooth, whether the pain comes from that tooth should be confirmed with tests.

Can sinusitis cause toothache, and how can I tell?

It can; the NHS lists toothache among the symptoms of sinusitis. Several upper back teeth on the same side hurting at once, pain getting worse when you bend forward, and a blocked nose suggest the sinus. The detailed distinction is on the page about toothache from the sinuses.

Nothing was found in the tooth. Is the pain psychological?

It is not right to jump to that conclusion. The systematic review divides toothache felt without a visible cause into eight groups, including pictures coming from muscles, nerves, the sinus, the heart and the blood vessels; pain of psychosocial origin is only one of them. Finding no cause in the tooth means the source needs looking for in another specialty.

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