The exposed nerve should be treated separately according to the situation.If accidental pulp penetration is caused during decay and cavity preparation, and the diameter of the exposed pulp hole is <0.5mm, pulp protectors such as calcium hydroxide can be placed at the pulp penetration to promote nerve recovery and maintain asepsis. If no significant pain is produced you can first perform padding and then directly fill the fossa. If the exposed pulp hole is >0.5mm, an inactivating agent such as arsenic trioxide can be placed and the inactivated pulp removed after 48 hours for root canal preparation and filling or directly under local anesthesia to complete the root canal treatment by removing the pulp. If the pulp is exposed for a long period of time and becomes infected and necrotic, the unshaped pulp needs to be cleaned and the root canal disinfected thoroughly before the root canal is filled and the crown restored.