Five-year-old babies grinding teeth at night in their sleep may be due to a period of tooth replacement, oral diseases and other causes. 1. in the period of tooth replacement: part of the 5-year-old baby has entered the period of tooth replacement, occlusal system line disorders, there may be the case of grinding teeth at night when sleeping, with the loss of milk teeth, the growth of permanent teeth, grinding the teeth of the situation will be relieved, parents do not have to worry too much. 2. Oral disease: if the baby suffers from gingivitis, periodontitis and other oral diseases, resulting in pain or swelling and other discomfort in the baby’s mouth, may also lead to the baby sleep at night when the situation of grinding teeth. Because of the five-year-old baby night sleep grinding more factors, so when the baby discomfort or continued grinding teeth, it is recommended that timely to the hospital for examination, as soon as possible to determine the cause of active treatment, to avoid the adverse effects of delayed condition.