Cracked Tooth and Sensitivity: Causes, Relief, and Care
Cracked teeth are frequently missed, and not because they are subtle to the person experiencing them.
They are missed because the symptoms are intermittent. The tooth hurts on one particular bite, then behaves normally for days. It is sensitive to cold sometimes and not others.
That inconsistency is characteristic, and understanding why it happens makes the problem much easier to recognise.
Why Does a Cracked Tooth Cause Sensitivity?
Why does it only hurt sometimes?
A crack creates a plane through the tooth along which the segments can move fractionally. When you bite in a way that separates them — usually on something hard, or with a particular cusp — the segments flex apart, and fluid within the exposed dentinal tubules moves rapidly. That fluid movement stimulates nerve endings at the pulp, producing a sharp sensation. Characteristically the pain is felt on releasing the bite rather than on applying pressure, because that is when the segments snap back together. Cold sensitivity occurs by the same mechanism, with the temperature change causing fluid movement through the crack into open tubules. Because it depends on hitting the tooth at precisely the right angle, it does not happen with every bite — which is why the problem can persist unrecognised for months.
Types of Crack
Craze lines. Superficial cracks confined to enamel, extremely common, particularly in adults. They cause no symptoms and generally need no treatment beyond monitoring.
Fractured cusp. A piece of the tooth, usually around a large filling, cracks and separates. Often occurs suddenly, and once the fragment is gone the pain frequently settles. Restoration is still needed.
Cracked tooth. A crack running from the biting surface toward the root, not yet separated. This is the classic cracked tooth syndrome presentation, with pain on release and intermittent cold sensitivity. The outcome depends on how far the crack has extended.
Split tooth. The crack has progressed completely through, separating the tooth into segments. Part or all of the tooth usually cannot be saved.
Vertical root fracture. Begins in the root and extends upward, often in root treated teeth. Frequently found late, and the prognosis is generally poor.
See cracked tooth.
What Causes Cracks
• Grinding and clenching, which apply sustained heavy loads — see teeth grinding
• Large existing fillings, which leave the surrounding walls thin and unsupported — see can a large filling break your tooth
• Biting something unexpectedly hard — a stone in food, a bone, ice, or packaging
• Root treated teeth, which are more brittle and lack internal structure
• Temperature extremes in rapid succession
• Trauma to the face or jaw
• An uneven bite concentrating force on one tooth — see bite feels off
• Age, since cracks accumulate over decades of loading
Lower molars and upper premolars are the most commonly affected.
How Cracks Are Identified
Diagnosis is often the difficult part, because cracks frequently do not show on radiographs.
• Bite testing on individual cusps to reproduce the pain on release
• Transillumination, shining a light through the tooth — a crack interrupts the light
• Staining with dye to reveal the crack line
• Magnification
• Removing an existing filling to inspect the floor of the cavity
• Cold testing to assess the pulp
• Radiographs, which may show a vertical bone defect associated with a root fracture
Sometimes a crack is only confirmed once a filling is removed, which is why the diagnosis is occasionally staged.
Managing Symptoms Before Treatment
• Chew on the other side and avoid the affected tooth entirely
• Avoid hard, crunchy, and chewy foods
• Avoid very cold and very hot items
• Use a desensitising toothpaste, rubbing a little onto the tooth as well as brushing
• Take ordinary painkillers according to the label if needed
• Do not place aspirin or painkillers against the gum, which causes burns
• Do not delay assessment because the pain comes and goes
See best temporary toothache relief before your appointment.
Treatment Options
Monitoring. For craze lines and some minimal cracks, with photographs and review.
A bonded restoration. Where a small fragment has fractured and remaining structure is sound. See white fillings.
A cusp-covering onlay or crown. The mainstay for cracked teeth. Covering the cusps binds the segments together and stops them flexing, which is what relieves the symptoms. See dental crowns and can a crown stop your tooth from cracking.
Root canal treatment. Where the crack has extended into the pulp and the nerve is irreversibly inflamed. See root canal.
Extraction. Where the tooth has split or a vertical root fracture is present. See missing tooth.
A night guard. Where grinding contributed, this protects the restored tooth and the others. See night guards.
Sometimes a temporary band is placed around the tooth first to see whether stabilising it settles the symptoms, which helps predict how the tooth will respond to a crown.
When Professional Dental Assessment May Be Needed
Arrange an assessment if:
• A tooth hurts when you release a bite — see pain when biting
• Sensitivity to cold has become sharper or more frequent — see tooth sensitivity
• A piece of tooth has broken away — see broken tooth
• Pain is spontaneous or wakes you — see toothache
• There is swelling of the gum or face — see dental abscess
• A tooth feels different from how it did before
• You have been told a tooth has a crack and are unsure what to do
Facial swelling, fever, or difficulty swallowing needs urgent care. See emergency dentist.
The NHS provides general information about broken teeth at nhs.uk/conditions/broken-tooth/.
Reducing the Risk
• Wear a night guard if you grind
• Avoid chewing ice, hard sweets, and popcorn kernels
• Do not open packaging with your teeth
• Have large fillings assessed for whether coverage would protect the tooth better
• Report an uneven bite rather than adapting to it
• Attend regular check-ups
• Wear a mouthguard for contact sport
Key Points to Remember
• Pain on releasing a bite is the characteristic sign of a crack
• Symptoms are intermittent because they depend on loading the tooth in a particular way
• Cracks frequently do not appear on radiographs
• Craze lines are common and usually harmless
• Cusp coverage is the usual treatment, as it stops the segments flexing
• A split tooth or vertical root fracture often cannot be saved
• Grinding is the most common contributing factor
Frequently Asked Questions
1. Can a cracked tooth heal itself?
No. Enamel and dentine do not repair a crack. The pulp can lay down reparative dentine internally in response to irritation, but the crack itself remains and can extend.
2. How do I tell a crack from ordinary sensitivity?
Ordinary sensitivity is usually provoked by temperature and affects a broader area. A crack typically produces sharp pain on releasing a bite on one particular spot, and comes and goes. Testing individual cusps during an examination distinguishes them.
3. Is a cracked tooth an emergency?
Not usually, unless there is swelling, severe pain, or a large fracture. It should still be assessed promptly, because cracks tend to extend and the treatment needed changes as they do.
4. Will a crown resolve the problem?
Cusp coverage stops the segments flexing and commonly relieves symptoms. Where the crack has already reached the pulp, root canal treatment may also be needed, and where it extends into the root the tooth may not be restorable.
5. Can stress cause teeth to crack?
Indirectly. Stress is strongly associated with clenching and grinding, which apply heavy repeated loads. Managing the habit, often with a night guard, reduces the risk.
6. What happens if I leave it?
Cracks tend to propagate under continued loading. A crack that could have been managed with coverage can extend into the pulp, requiring root canal treatment, or into the root, at which point the tooth is usually lost.
Conclusion
The intermittent nature of cracked tooth pain is not a sign that it is minor. It is a direct consequence of how cracks behave — they only hurt when loaded in a particular direction.
Because cracks extend rather than resolve, the useful response is assessment rather than waiting to see whether it settles. Treated while the crack is confined to the crown, the tooth can usually be protected. Left long enough, the options narrow.
If you have a tooth that hurts on release or is intermittently sensitive, you are welcome to book an appointment at Wimpole Dental, 22 Wimpole St, London W1G 8GQ, or call 020 7183 0692.
Dental symptoms and treatment options should always be assessed individually during a clinical examination.
Dental Disclaimer
This article is for general educational information only and is not professional dental advice, diagnosis, or a treatment recommendation. Information here is general and cannot replace an in-person assessment by a qualified, GDC-registered dental professional. Symptoms, suitability, fees, timelines, and outcomes vary according to individual clinical circumstances. If you have pain, swelling, or other concerning symptoms, seek prompt professional dental care. Always request a written treatment plan and cost estimate before proceeding with treatment.
Written Date: 31 July 2026
Next Review Date: 31 July 2027
Written by Dr Kamran Yazdi · reviewed by Dr Kamran Yazdi, GDC 197926
This article is general information, not personal clinical advice. For a diagnosis and a plan tailored to you, book a consultation with a GDC-registered dentist.
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