What causes mouth ulcers in a three-and-a-half-year-old child?

The possible causes of oral ulcers in a three-and-a-half-year-old child may include the following: 1. **Unbalanced diet**: If a child frequently consumes spicy, irritating, or excessively hot food, it may damage the oral mucosa and lead to oral ulcers. Parents are advised to provide children with mild and nutritionally rich foods. 2. **Vitamin deficiency**: Deficiencies in vitamins such as vitamin B and vitamin C may lead to oral ulcers. Parents should ensure children consume sufficient vegetables and fruits. If necessary, vitamin supplements may be taken under medical guidance. 3. **Poor oral hygiene**: Bacterial growth due to inadequate oral hygiene can also cause oral ulcers. Parents should teach children to rinse their mouths after meals and develop the habit of brushing teeth in the morning and evening. 4. **Trauma**: Children may accidentally bite their oral mucosa while playing, which is another common cause of oral ulcers. Parents should pay attention to children's safety to prevent such incidents. If concerned, please consult a healthcare professional.