Sparse milk teeth, but the number is quite a lot is generally a normal phenomenon, the number is not enough is congenital missing milk teeth, if the sparse small obvious, with heredity, malnutrition during pregnancy, infants and young children sick and so on. Sparse milk teeth with gap is also known as physiological gap. Generally speaking, the size of milk teeth is relatively small, and the existence of a certain gap in the middle is mainly to leave enough space for the eruption of permanent teeth. Therefore, if the baby’s milk teeth are slightly sparse, but the total number is normal, this is still a normal phenomenon, and there is no need to worry and intervention. However, at the age of 2.5 years old, if the total number of baby teeth is not enough, then we should pay attention to the possibility of “congenital missing milk teeth”. If the milk teeth are sparse, small and particularly obvious, generally considered to be dental dysplasia. The first factor to consider is hereditary, because the position, arrangement and shape of the teeth, like other parts of the human body, have a clear genetic predisposition. Secondly, malnutrition, endocrine dysfunction, infectious diseases or malpositioning of the fetus during pregnancy, and acute and chronic diseases such as chronic gastroenteritis, rickets, acute infectious diseases and tuberculosis infections in childhood can lead to the appearance of excessively sparse and small milk teeth in young children.