Tooth decay filling needs anesthesia in the following cases: 1. Oral examination reveals that the cavity is deep, soft decay exists at the bottom of the cavity, probing reveals that there is obvious soreness at the bottom of the cavity, X-ray shows that it is close to the pulp, it is better to remove all the decay, prepare the cavity shape under local infiltration anesthesia, use zinc oxide clove oil to close the cavity, and use glass ionomer or composite resin to fill it after 1-2 weeks of soothing analgesia. 2. X ray shows that pulp exposure has occurred in the cavity, it is impossible to open the pulp directly, it is necessary to inject anesthetic before grinding open the pulp cavity, remove the infected pulp, carry out root canal preparation, and repair the cavity or make inlay or full crown restoration after the root canal is filled.