Cracked tooth and vertical root fracture
- Oral pathology
A cracked tooth hurts sharply on biting, often when the bite is released. Cracks grow, and a crack that splits the root usually means losing the tooth.
What it is
Cracks run from harmless enamel craze lines to cracks into dentine and pulp, split teeth and vertical root fractures. A cracked tooth is typically a lower molar or upper premolar with a large filling, in someone who clenches or grinds. The crack flexes on biting, moving fluid in the dentine, which causes sharp, brief pain. Vertical root fractures usually occur in root-filled teeth, especially with posts.
How to recognise it
- Classic symptom: sharp pain on biting on a particular cusp, often on release of the bite; sensitivity to cold.
- Tests: biting on a bite stick cusp by cusp, transillumination, dye and magnification; cracks rarely show on radiographs.
- Craze lines (enamel only) are normal and need no treatment.
- Vertical root fracture: a narrow deep pocket, a sinus tract close to the gum margin and a J-shaped radiolucency along the root.
- Risk factors: large fillings, root canal treatment without cusp coverage, posts, bruxism and chewing hard objects.
Differential and risks
- An early crack is protected with cusp coverage (onlay or crown) to stop it growing; if the pulp is affected, root canal treatment too.
- A crack extending deep under the gum or through the root floor has a poor prognosis.
- A vertical root fracture cannot be repaired predictably: the tooth or root is usually extracted.
Next step / Initial management
- Pain on biting with a normal radiograph: suspect a crack and do a bite test cusp by cusp.
- Suspected crack: refer to the dentist promptly for cusp protection before it propagates; a temporary band or crown may be used.
- Root-filled tooth with a narrow deep pocket or sinus tract near the gum: refer for assessment of vertical root fracture.
Test yourself
Think of the answer, then tap the question to see it.
What symptom is typical of a cracked tooth?
Sharp pain on biting on a cusp, often when the bite is released.
Why are radiographs of limited use for cracks?
Cracks are thin and usually run parallel to the X-ray beam, so they rarely show until bone is lost.
What is the usual outcome of a vertical root fracture?
Extraction of the tooth or the affected root, because it cannot be repaired predictably.
Connections
Educational content; it does not replace assessment by a dentist or doctor and is not a clinical instruction. For facial or neck swelling with difficulty swallowing or breathing, a knocked-out tooth or bleeding that will not stop, go to an emergency department at once.
Sources: Cracked Tooth Syndrome (StatPearls Publishing (NCBI Bookshelf), 2024); Tooth Fracture (StatPearls Publishing (NCBI Bookshelf), 2025); True vertical tooth root fracture: Case report and review (Contemporary Clinical Dentistry (PMC open access), 2011).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.