Cracked tooth is defined as an incomplete fracture initiated from the crown and extending subgingivally. The fracture lines are almost always in mesio-distal direction. They may extent the whole mesio-distal lenght of the crown, but may also be either mesial or distal only. Cracked tooth is a problem found in premolars and molars. No separate fragments can be found in a cracked tooth.
Symptoms are highly variable, from symptomfree to almost continuous low-grade pain. Fracture lines are not visible in the radiographs because of their orientation.