Babies generally teething around 6 months of age, if at 14 months of age still not teething is abnormal, 11 months of age not teething relatively late most of the factors related to the following: 1, premature, twins or the mother in the second trimester has obvious calcium deficiency performance. 2, less outdoor activities, indoor lighting is poor in time to sunshine. 3, after birth from half a month of age is not given on time to supplement vitamin D. 4, not added on time The food should be close to solid at 11 months of age, relatively coarse to promote the baby’s chewing, because chewing is conducive to the eruption of teeth, if the food is too fine, thin and soft, the teeth will erupt later. 5, if there is also mental retardation or special facial features, we should pay attention to the possibility of congenital genetic metabolic disease, need to go to the hospital for timely examination.