One and a half year old babies grinding teeth may be related to intestinal parasites, mental stress, malnutrition and so on. 1. Intestinal parasites: If the baby has intestinal parasites, some toxins produced by the parasites will cause nerve excitation, causing teeth grinding. 2. Mental tension: babies who are too nervous and anxious may also cause teething symptoms, especially at night when they sleep. 3. malnutrition: babies picky eaters, after a long time will cause the baby malnutrition, lack of calcium, lack of vitamins, etc., cause the baby grinding teeth. One and a half year old baby grinding teeth may also have other reasons, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, under the guidance of the doctor’s treatment.