It is necessary to replace a broken milk tooth at the age of 9. Children’s milk teeth are damaged or missing, if not timely replenishment, may often toothache, the children’s emotions as well as life, learning will have an impact. If the milk teeth are moth-eaten or other injuries, not timely fillings, may also affect the normal chewing, food is not chewed directly into the gastrointestinal tract, will affect the gastrointestinal digestion, resulting in gastrointestinal peristalsis slowed down, easy to cause gastrointestinal diseases. If the broken milk teeth are incisors, not timely fillings, it will affect the aesthetics, which may lead to children’s self-confidence decline and other psychological problems. Nine-year-old children with broken milk teeth, need to fill the teeth as soon as possible, so as not to cause the above hazards, but the specific should be under the guidance of a professional physician to choose the best filling material. In addition, usually also need to pay attention to oral hygiene, insist on brushing every morning and evening and rinsing after meals, so as not to aggravate the degree of caries.