Eruption of teeth

The process by which developing teeth move upwards through the jawbone and break through the gum to project into the mouth. Deciduous teeth (milk teeth) usually begin to appear at about 6 months of age. All 20 deciduous teeth have usually erupted by 3 years (see teething). Permanent teeth (also known as secondary teeth) usually begin to appear at about 6 years of age. The first permanent molars erupt towards the back of the mouth and appear in addition to the deciduous teeth. The eruption of permanent teeth nearer the front of the mouth is preceded by reabsorption of the roots of the deciduous teeth, which become loose and detach. Eventually, permanent teeth replace all the deciduous ones. Wisdom teeth (the backmost, or 3rd, molars) usually erupt between ages 17 and 21, but, in some people, they never appear.