5-year-old children with tooth decay (clinically known as caries) need to be filled in a timely manner to avoid tooth pain or affecting the normal eruption of permanent teeth. 1. If dental caries is not treated with filling in time, it will cause pain when eating with hot and cold stimulation; if the caries has damaged the nerve of the tooth, it will also cause symptoms of pulpitis such as hot and cold pain, spontaneous pain or occlusal pain, etc. It is necessary to carry out root canal treatment before filling and restoration. 2. When dental caries causes apical periodontitis, it will lead to the spread of inflammatory substances to the embryonic tissues of the permanent teeth in the root of the milk teeth, which will lead to its infection and cause the abnormal eruption of the permanent teeth, or the eruption of the permanent teeth after the emergence of the dental hard tissues of demineralization and underdevelopment and other symptoms. Therefore, it is recommended that 5-year-old children who have dental caries should be treated with dental filling and restoration in order to prevent toothache and other symptoms.