Spontaneous pain, pain at night, or sharp pain in chewing at a fixed point, suggests that the fissure has affected the nerve of the tooth. Superficial fissures usually have no obvious symptoms, but if the fissure is deeper and reaches the dentin, there will be sensitivity to hot and cold stimuli or discomfort in biting, and deeper fissures will cause sharp pain in chewing at fixed points when they reach the nerves of the teeth. If the fissure reaches the enamel-dentin boundary without obvious discomfort symptoms, it can be treated with acid etching and enamel bonding agent for light curing; if the fissure reaches the dentin, it is necessary to repair it with filling after cushioning. If the fissure reaches the nerve of the tooth, root canal treatment is needed, and full crown restoration is carried out at a later stage to protect the tooth. Cracked teeth must be timely to the hospital, clear depth of the crack for active treatment, so as not to delay the condition.