The causes of red and swollen gums in children include the following: First, food impaction: the gap between the milk teeth is large, often embedded celery, beef and other coarse fiber food, stimulating the gum papilla red, swollen, swollen and painful. Second, the rise in the number of bacteria in the neck of the teeth: children like to eat too sweet, sticky food, a lot of soft tartar and plaque, etc. Retained in the neck of the teeth, causing a rise in the number of bacteria, resulting in swelling of the gingival margin. Third, apical periapical inflammation: the formation of deep caries in milk teeth, triggered by apical periapical inflammation, inflammatory secretions in the pulp cavity can penetrate out of the apical foramen, break through the bone wall, the formation of fistulas or sinus tracts on the surface of the gums, resulting in redness and swelling of the soft tissues. Fourth, external factors: under the action of external forces, the periodontal shock of milk teeth, there is obvious loosening, and there is also swelling of the surrounding soft tissues, resulting in chewing pain. Fifth, the plaque factor: the application of silver amalgam and other filling cavities, adjacent to the formation of overhanging protrusions can be adhered to a large amount of plaque, resulting in gingival swelling and pain.