The lower incisors came in at the age of 4 months, and no teeth have come in since then. This may be due to genetic factors, lack of calcium, and improper addition of supplemental food. 1. Genetic factors: If one of the parents is delayed in teething, the child will usually be delayed in teething as well. 2. Lack of calcium: usually caused by a lack of calcium, the baby’s lack of calcium will cause a delay in the eruption of teeth, you can often go to the outdoors, more sunshine, and so on. 3. Unreasonable addition of complementary foods: If parents do not add hard foods in time to help their children’s teeth erupt after teething, they may grow lower incisors and then have no teeth afterward. There may be other reasons why the lower incisors grew at the age of 4 months and no teeth have grown since then. It is recommended that the child go to the hospital in time for a complete examination to clarify the cause of the disease and then give targeted treatment or therapy.