Cracked tooth: pain that does not show on an X-ray

The description is usually the same: a short, sharp pain when biting on something in particular, but not every time. An X-ray is taken and shows nothing. This is the classic opening of cracked tooth syndrome.

Cracks run parallel to the long axis of the tooth. Because the X-ray beam passes through the same plane, the crack usually does not register on the image. Diagnosis therefore rests on symptoms and clinical tests.

The distinguishing sign: pain on release

In a cracked tooth the pain often comes not while biting but at the moment you release. Biting separates the two parts of the crack, releasing snaps them back together, and that sudden movement in the dentinal tubules becomes a nerve signal. This finding sets it apart from other types of pain.

• Pain when biting on one particular spot, not repeating with every bite
• A sharp pain at the moment of release
• Sensitivity to cold that increases but does not linger
• Difficulty pinpointing exactly which tooth hurts

How it is detected

A bite test applies pressure to each cusp in turn and shows which area produces pain. Transillumination, shining light through the tooth from behind, reveals where the crack interrupts the light. Staining and examination under magnification are also used. Some cracks only become visible once an existing filling is removed.

Treatment follows the depth of the crack

Superficial enamel cracks often need no treatment and are monitored. Cracks extending into dentine are treated with a restoration that holds the tooth together, usually a crown or onlay; the aim is to stop the cusps from flexing apart. If the pulp is involved, root canal treatment comes first, followed by the protective restoration.

A cracked tooth is one of the few dental problems where time works against you. Waiting narrows the options.

This content is for general information and does not replace an in-person examination. Treatment decisions should only follow a clinical assessment.