All 20 milk teeth that erupt in children before the age of 3 are gradually replaced with permanent teeth during the tooth replacement period.
The first teeth that first emerge in children are called milk teeth and begin to grow in some infants after more than 4 months and in others after 11 months. Most of the lower two baby incisors come in first and then gradually grow full and flush, totaling 20 milk teeth.
They are gradually replaced by permanent teeth as they grow, with milk incisors replaced by permanent incisors, milk cuspids replaced by permanent cuspids, and milk molars replaced by bicuspids.
At the age of 6+, babies begin to change their teeth, and the permanent teeth that come in are the first molars. The first molars do not replace the milk teeth, but come straight out from behind the last milk teeth. Between the ages of 6 and 12, milk teeth are gradually replaced by permanent teeth in the same position. At this age, milk teeth alternate with permanent teeth.
Parents should take calcium supplements and allow their children to get plenty of sunlight during the tooth replacement period to facilitate the eruption of new teeth.