Only the crown is visible in the mouth while the roots that support the tooth are firmly anchored in the jaw bone. The gingiva, or gum tissue, is a protective type of skin that clings to the necks of the teeth and covers the bone holding the teeth. The molar teeth are located in the back of the mouth and may have two or three roots. Most of the other teeth only have one root. There are usually four wisdom teeth, one on the upper and lower on each side of the mouth.
Wisdom teeth begin to form at nine years of age.
Then as the root develops, the teeth begin to move slowly through the bone towards the mouth. By approximately age sixteen the jaws have reached their adult size and this determines whether there will be enough room for the wisdom teeth to erupt into the mouth normally. If there is not enough room for the wisdom teeth to come in, they will remain trapped in the jaw bone. Impacted teeth can take many positions in the bone as they attempt to find a pathway that will allow them to erupt successfully. Sometimes part of the wisdom tooth shows in the mouth.