Cracked tooth syndrome is identified more by symptoms than by actually seeing cracks in a tooth. X-rays do not show cracks in teeth either. The primary symptom is pain on biting. Sensitivity to cold is often reported. The pain from biting occurs due to the flexure of the crack when the tooth is put under a load, as in chewing.
In almost every instance, the cracked tooth has a sizable filling. A tooth with a large filling has been hollowed out- first by decay and them by replacing the decay with a filling. Over time the weakened remainder of the tooth builds up small fracture lines that become larger and deeper. In addition, a tooth becomes more brittle with age which leads to more fracture lines.
Success in treating a cracked tooth depends on the extent of the crack. Most cracks (90%) do not extend to the nerve of the tooth and will desensitize themselves over time. In some cases (9%) cracked tooth symptoms are treated with a crown. A crown acts like a belt to hold the tooth together. In those cases in which the crack extends to the nerve, a root canal is necessary to treat the injured nerve. In very rare cases (1%), the crack may extend through the length of the tooth and an extraction may be necessary.