Severe periodontitis can lead to infections that crack the tooth, mainly because after heavy resorption of the alveolar bone, the crown-to-root ratio of the tooth is out of balance and the tooth becomes weak when biting, loose or painful in the periodontal tissue, which is similar to the sensation of a cracked tooth.
In addition, deep caries can also be felt as a cracked tooth, and food entering the cavity when eating causes pain in the nerve, similar to the severe pain of a cracked tooth, which disappears immediately after removing the stimulus. There is also a loss or fracture of the filling which can lead the patient to mistake it for a cracked tooth.