Possible causes of pain after making porcelain crowns for living pulp teeth and the treatment: 1. Allergic pain (transient sensitivity when eating hot, cold, sour or sweet food, or mild pain and discomfort) ① Short-term allergic pain may be due to the high-speed lathe needles cutting the hard tissues of the dentin, which puts the pulp in a congested state; the stimulation of the pulp by the restorative bonding agent. If the various stimuli mentioned above are within the tolerance range of the pulp, the allergic pain will disappear in a short period of time. On the contrary, if the stimulation exceeds the tolerance range of the pulp, pulpitis will occur and endodontic treatment is required. ② Pain that occurs after the restoration has been worn for a period of time may be due to exposure of the neck of the tooth due to secondary caries, dissolution of marginal adhesive or recession of the gums. Treatment: The restoration should be checked for loosening, marginal microleakage generation, adverse stimulation of the gingiva by the edge of the restoration, and gingival recession. Marginal gaps caused by the dissolution of the cementum, easy to loosen close to falling off, can be removed and then use bonding cementum to re-seal. Dentin hypersensitivity caused by gingival recession can be treated with desensitizing agents. Other restorations must be removed and restored. 2, spontaneous pain After bonding, the cause is pulpitis, apical periodontitis or periodontitis. Mostly due to the damage to the pulp of the tooth preparation, the formation of acute pulpitis or pulp necrosis, acute attack of chronic pulpitis; or dentition trauma caused by acute periodontitis, apical inflammation and so on. If spontaneous pain appears after a longer period of restoration, it is mostly related to the quality of the restoration. Secondary caries or secondary caries caused by loosening of the restoration, or due to imperfect root canal treatment before restoration. Treatment: Spontaneous pain caused by pulpitis, often due to the restoration cover is not easy to check and locate, do not remove it easily, should be carefully examined whether the restoration is loose, the edge of the fissure, there is no dentition obstruction. Then, temperature test and pulp vitality test should be done. If there are periodontal symptoms, percussion and oral examination should be carried out in order to determine whether there is any lesion of periodontal tissues and whether there is any lateral penetration of the root wall. Pulpal inflammation is identified and endodontic treatment is performed as appropriate. If it is caused by periodontal inflammation, it should be based on the clinical and periodontal destruction, the degree of looseness of the affected teeth, X-rays and so on to decide whether the affected teeth are retained. 3, occlusal pain ① restorations cemented soon after the occlusal pain, and obvious knocking pain, generally caused by early contact traumatic dentition (which is commonly known as the bite with high). Treatment: after bonding, the symptoms disappeared. ② Some time after cementation, consider whether it is due to periodontal disease or apical periodontitis caused by chronic traumatized dentition. Treatment: Endodontic treatment, sometimes combined with periodontal treatment. The above can only generally describe the causes of pain in living pulp teeth with porcelain crowns and the basic principles of treatment, the specific circumstances also need to be examined and then make the appropriate treatment plan.