A tooth that hurts when you chew: what is it a sign of?

A tooth is not fixed rigidly to the bone. Between the root and the bone there is a thin connective tissue called the periodontal ligament; it cushions the tooth, and thanks to the pressure sensors inside it you can feel how hard the thing you are biting is. Pain that comes on when you chew comes from this tissue and from the area at the tip of the root. Pain from the nerve inside the tooth is usually different: it is triggered by heat, cold and sweet things, and may have nothing to do with biting. But the exception matters: if there is a crack in the tooth, the force of biting moves the pieces and the pain once again comes from the living tissue inside. That is why pain on pressure does not, on its own, rule out the possibility that the nerve is still alive.

This distinction is half the diagnosis. A tooth that jumps at cold water but causes no trouble when you bite tells you a living nerve is being irritated. A tooth that does not react to cold at all but hurts when you bite tells you the opposite: the nerve inside has died and the inflammation has moved to the root tip.

The most harmless cause is a filling that is too high. If a new filling or crown is even a hair's breadth higher than its neighbours, every time you close your jaw that tooth touches first and takes the load on its own; the connective tissue underneath gets bruised. The sign is clear: the pain starts straight after the procedure and is not there when you are not using the tooth. Fixing it takes a few minutes in the dentist's chair.

The second cause is inflammation at the root tip. Deep decay or an old injury kills the living tissue inside the tooth; bacteria travel the whole length of the root canal, reach the bone through the tip of the root and set off inflammation there. The tooth hurts when you bite and hurts when it is tapped, and patients usually describe it as feeling 'longer'. The pain is dull, becomes constant and gets worse at night when you lie down. This picture does not get better on its own: the source is in a closed space inside the tooth, and the immune system cannot reach it.

The third cause is cracked tooth syndrome, and its signature is very distinctive: the pain comes not while you are biting but the moment you release your bite. The cause is mechanical. Under the force of biting, the crack lets the two sides of the tooth move slightly apart; when you take the pressure off, the pieces close back together and irritate the living tissue inside. The result is a short, sharp, stabbing pain. Because a crack leaves no trace on a standard X-ray, patients can go for years being told 'there is nothing wrong'; all that time, the crack goes a little further with every bite.

The fourth cause is a broken tooth, and here there are two different outcomes. A cusp breaking off the chewing surface does not cost you the tooth; the remaining structure is covered with a crown and the tooth keeps working. A vertical fracture that splits the root from end to end, however, opens a path for bacteria that cannot be sealed, and there is nothing left of that tooth that can be saved. What separates the two is not how severe the pain is, but how far down the fracture goes.

Not every tooth that hurts when you chew is an emergency, but some carry an urgency measured in hours. What makes the difference is not how severe the pain is, but what comes with it.

With pain on pressure, choosing the right treatment depends on finding the right cause. The sequence below is for diagnosis, not treatment; at the end, it becomes clear which tooth hurts, for what reason, and whether that tooth can be kept.

1. 1

   We take the history of the pain

   Does the pain come when you bite or when you let go, what do cold and heat do, and has that tooth had a filling or root canal treatment in recent months? These three answers narrow down the cause considerably.

2. 2

   Bite test

   We ask you to bite on the cusps of the chewing surface one at a time with a bite stick. The crack lies under whichever cusp brings on pain when you let go. This simple test is the method that pinpoints a crack that a standard X-ray cannot show.

3. 3

   Vitality and percussion test

   With a cold test, we check whether the tissue inside the tooth is alive. A tooth that does not respond to cold at all and hurts when tapped is the picture of inflammation at the root tip. If it responds to cold excessively and for a long time, the tissue is still alive and the plan changes.

4. 4

   Bite check

   Using articulating paper, we check which tooth touches first when you close your jaw. The cause of pain that started after a new filling becomes visible here, and it is corrected in the same session.

5. 5

   Imaging

   A periapical X-ray shows inflammation at the root tip as a dark shadow, but it does not show a crack. A cone beam CT (CBCT) scan reveals the shape of bone loss and vertical fractures in the root; with a fine crack, the image comes out clear, and this does not rule out a fracture. The definite answer comes from seeing the crack directly once the old filling has been removed.

Treatment varies with the cause, and the gap is large: at one end there is a five-minute adjustment, at the other an extraction. The list starts with the least invasive.

Pain on pressure is not a symptom that clears up on its own over time. What follows was written not to frighten you, but so that you can ask the right question whichever dentist you see.

Healing time varies with the cause. The sequence below shows what happens on each of the four different paths.

1. If the bite has been adjusted: two to five days

   The bruised connective tissue takes a few days to recover. On the first day the tooth is still tender, then this fades quickly. If the pain is still there on the fifth day, the bite is checked again.

2. If root canal treatment has been done: a few days, then months

   For a few days after the procedure you will feel tenderness when you bite, and this eases each day. The inflammation in the bone takes months to heal, and we follow this with check-up X-rays. Until the crown is fitted, do not bite hard things on that side.

3. If a crown has been fitted: the pain ends in the first few days

   As soon as the cusps are bound together, the crack stops moving and the pain on biting goes away. If you have a history of clenching at night, we bring in a night guard during this period; if the force producing the crack is not dealt with, the neighbouring teeth are next in line.

4. If the tooth has been taken out: planning for the gap

   The extraction site closes over within a few weeks, and the real decision is what will fill the gap; this is where an implant comes into it. For a single tooth, standard implant treatment is enough. For patients who have lost many teeth for the same reasons, we sort out the whole mouth in a single plan: the implants lock mechanically into the hard basal bone deep in the jaw, into the cortical layer. A conventional implant, by contrast, is placed in the alveolar bone at the top, which shrinks along with the teeth; when there is not enough volume, bone is added first and fusion is waited for over months. That is where the difference comes from. Adding bone and months of waiting do not come into it, and at the end of the three clinical days you leave with your final fixed teeth.

We do not give a single figure on this page: behind the same symptom there may be a five-minute bite adjustment, or an extraction and a plan to be put in place afterwards. We give you the right figure after the examination and imaging. These are the items that determine the price:

The cause of the pain

A bite adjustment, root canal treatment, a crown and an extraction are completely different procedures, with different timescales, materials and numbers of sessions. A figure given before the cause has been identified is bound to change at the clinic.

Where the tooth is in your mouth

Back molars have more canals than front teeth, and treatment takes longer as a result. The same procedure means a different workload on a different tooth.

How many teeth are affected

If there is clenching at night or long-standing chewing on one side only, the problem does not stop at one tooth. A plan built around a single tooth and a plan covering the whole mouth are calculated separately.

The solution chosen after extraction

Whether the gap is filled with an implant or a bridge, and the material of what goes on top, have a direct effect on the total. We tell you the brand of the material we use in writing from the start.