Babies usually start teething at 4-6 months of age, when parents should pay attention to certain conditions in their children, such as itchy teeth or easy biting, refusal to eat milk or irritability, low fever, etc. However, there is no need to worry too much because this is a physiological phenomenon, as long as you massage the child’s teeth and clean the mouth. In general, the eruption of baby teeth should not exceed 6 months, and if they do not erupt after 1 year of age, you should go to the hospital to start the examination, which is an abnormal situation. Generally, 8 teeth erupt around 1 year old, 12 teeth erupt at 1.5 years old, 16 teeth erupt at 2 years old, and all 20 teeth erupt after 2.5 years old, but there are some children who are a little late, which is determined by genetic factors. Some children have better nutrition and erupt a little earlier, but there is a range and scope for late eruption and early eruption. However, parents should be aware of some situations such as crying, refusal to eat, low fever, irritability, etc., or some cases of redness and swelling of the gums, so that the baby teeth can erupt smoothly and the permanent teeth can be alternated.