A tooth that is good and hurts for no reason may be experiencing pulpitis, gingival papillitis or trigeminal neuralgia, or pain of cardiac origin. 1. Pulpitis. Teeth well for no reason pain, may be caries untreated, bacterial invasion of the pulp inflammation, resulting in pulpitis, there will be external hot and cold stimuli to produce severe pain can be sustained, the pulp vitality test is abnormal. 2. Gingival papillitis. When eating and drinking, food embedded in the teeth between the gap can cause papillitis, teeth have spontaneous pain, generally remove the embedded material after the pain will be significantly reduced. 3. Trigeminal neuralgia. Trigeminal neuralgia when the trigger point is touched, may cause a brief knife-like pain, lasting a few seconds after the pain will immediately disappear, often easily confused with pulpitis. 4. Cardiac pain. Angina and other cardiac diseases will be involved in toothache, usually radiating pain, oral dental examination is generally no abnormality but the electrocardiogram can be found abnormal. If you have a good toothache for no reason, it is recommended that you go to the hospital to confirm the cause of the toothache by combining oral clinical signs and laboratory tests.