At the age of 6, the 1st permanent molars, which we call "6 year old teeth", begin to erupt after the milk molars. These teeth are four in total, two on each side of the lower and upper jaw. Between the ages of 7-11, deciduous teeth begin to shake and permanent teeth from below begin to take the place of deciduous teeth.

This period, when both milk and permanent teeth are present in the mouth, is called the mixed dentition period. At the age of 12, the 2nd permanent molars erupt behind the 6 year old teeth. Like the 6 year old teeth, these are teeth that do not erupt in place of a milk tooth.