It is actually normal for babies to be teething at four and a half months. Although the age recorded in the book is around six months, everyone teethes at a different time. If the baby’s development in all areas of the body is in line with other children, then parents do not need to worry too much. Once babies start to erupt their milk teeth, parents should start brushing their teeth, especially for babies who need to drink milk and are very susceptible to bottle caries. Milk teeth are the key to jaw building, and they are also the necessary teeth for children between the ages of three and six to eat food, so parents must take good care of them. Brushing can use finger toothbrush or sterile gauze, and you can not use toothpaste first, just use salt water, or is to use water to clean off the surface of the teeth attached to the milk stains, so as to ensure the healthy growth of milk teeth.