If your child’s teeth have not grown out in half a year, the possible clinical causes include lack of nutrients, missing roots, and gum wear. 1. Lack of nutrients: The development of teeth requires the support of calcium, vitamin D and other nutrients. Insufficient nutrient intake will result in a lack of the relevant nutrients, thus affecting the eruption and development of teeth. 2. Root loss: If the root of the tooth is missing due to trauma after the first tooth loss, the tooth may not be able to erupt. 3. Gum abrasion: If the gums of the missing tooth are not protected after the first tooth loss, constant abrasion may cause difficulty or slow eruption of the new tooth. In this case, parents are advised to take their children to a hospital dentist for consultation and treatment.