1. Observe the tooth socket: It is necessary to observe the tooth socket when taking out the gelatin sponge after tooth extraction. After falling, a blood clot will form inside the tooth socket, and there will be no blood clot without falling off.
2. Observe whether there are white objects: the gelatin sponge is white, and the gelatin sponge is insoluble in water. If there is a white object, the gelatin sponge falls, and if not, it does not fall.