Cracked tooth syndrome: A toothache caused by a broken tooth (tooth fracture) without associated cavity or advanced gum disease. Biting on the area of tooth fracture can cause severe sharp pains. These fractures are usually due to chewing or biting hard objects such as hard candies, pencils, nuts, etc. Cracked tooth syndrome is most common in molars and in teeth with large fillings. Sometimes, the fracture can be seen by painting a special dye on the cracked tooth. Treatment usually is to protect the tooth with a crown. However, if placing a crown does not relieve pain symptoms, a root canal procedure may be necessary. The fracture may be so severe as to require removal of the tooth.