Because the pulp cavity and apical foramen of milk teeth are large, the fibrous component of the pulp tissue is small. Once the pulp has inflammation, it is easy to spread. The periapical migration is also more rapid, and the bone of the alveolar bone of children is looser than that of adults. The pulp cavity is large and develops quickly after infection. The reasons for the swelling of the face after the sealant may include: the sealant is too tight and the inflammatory pressure in the pulp cavity is too high, which leads to acute inflammation; or the pulp itself may be partially inflamed and infected to the periapical area, which is only induced by the sealant stimulation, and this phenomenon occurs in the milk molar with multiple roots. Therefore, although the symptom of swollen face after sealant is not normal, it is not uncommon in clinical practice and is not a difficult disease, and as long as the treatment is timely and proper, the inflammation can be eliminated and recovered quickly.