The best treatment for a 4-year-old child with tooth decay is to go to the dentistry department for decay and filling treatment for tooth malformation, because all the teeth in the mouth of a 4-year-old child are milk teeth, and there is at least 2 years before the tooth replacement, if the teeth have more serious decay, it may affect the child’s chewing, nutrition absorption and development, and the loss of teeth may lead to the incompleteness of the whole tooth row, forming the tooth row Therefore, it is recommended to treat the tooth decay of 4-year-old children as soon as possible. If the tooth decay is early, a single decay and filling treatment can achieve better results. If the decay is deeper and invades the pulp, root canal treatment for milk teeth can also be used to treat the tooth better.