The causes of periapical inflammation of milk teeth are as follows: 1. The hard tissue of milk teeth is thin, the dentin tubules are thick and permeable, and the bacteria and toxins in the caries damage are easy to invade the pulp. In addition, children’s physical and mental development is not mature, their perception ability and language expression ability are poor, and the nerve fiber of the pulp of milk teeth is not well developed, so the early symptoms of milk teeth pulpitis are not obvious, which cannot attract parents’ and children’s attention, and they do not come to the hospital in time; 2, there are more parapulpal canals and lateral parapores in the pulp base of milk teeth, so that after the infection of milk teeth pulp, it is easy to invade the root divergence through the parapulpal canals and parapores in the pulp base, which leads to the infection of milk teeth pulp The pulpal infection may spread to the periapical tissues and lead to periapical inflammation.