Cracked tooth: This is when a crack runs from the biting surface of the tooth down towards the root. Sometimes it goes below the gum line and into the root. A cracked tooth is not split into two parts but the soft, inner tissue of the tooth is usually damaged.
Craze lines: These are tiny cracks that affect only the outer enamel of the tooth. They are common in all adult teeth and cause no pain. Craze lines need no treatment.
Cracked cusp: The cusp is the pointed part of the biting surface of the tooth. If a cusp becomes damaged, the tooth may break. You will usually get a sharp pain in that tooth when biting.
Split tooth: This is often the result of an untreated cracked tooth. The tooth splits into two parts. Vertical root fractures are cracks that start in the root and go up towards the biting surface.