Whether or not a 3 year old needs a filling depends on the condition of the tooth. If trauma has resulted in a chipped tooth or deep caries, a filling is often needed. If it is shallow caries generally do not need fillings. 1. Trauma: If a baby has a chipped tooth due to trauma, if the tooth is not filled, the tooth may tilt over time, and symptoms such as tooth acidity and toothache often occur. 2. Deep caries: If the baby’s teeth are more seriously decayed, it is easy to have the symptom of plugging when eating, and the tooth decay may become more and more serious, and may even injure the pulp of the tooth to cause pulpitis, periapical inflammation, and need to fill the tooth in time. 3. shallow caries: if tooth decay is not very serious, generally do not need fillings, but usually pay attention to oral hygiene, and can be coated with fluoride treatment. Whether 3-year-old babies need fillings, must go to the hospital, by the doctor clear diagnosis.