A tooth that hurts when you knock on it, i.e. kowtowing pain, may be caused by periapical periodontitis, occlusal trauma and other diseases, which usually cannot be cured by itself, and requires root canal treatment and attuning treatment respectively, as follows. 1. Periapical inflammation: the pressure buildup of periapical tissues and inflammatory mediators lead to knocking pain in the affected tooth, which needs to be treated by root canal therapy to eliminate inflammation, including root canal preparation, root canal disinfection, root canal filling, and in case of apical cysts, apical surgical resection is needed. 2. Occlusal trauma: long-term occlusal trauma can lead to periodontal tissue damage, the affected teeth have knocking pain, can be adjusted to remove the affected teeth of the early contact and interference, if the affected teeth have hidden cracks, need to be filled and repaired. There may be other reasons for the pain in the teeth, it is recommended to go to the hospital in a timely manner, after clarifying the cause of the disease for targeted treatment.