Most adults have four wisdom teeth, one in each of the four quadrants, but it is possible to have none, one to three, or more than four, in which case the extras are called super numerary teeth. Wisdom teeth may get stuck against other teeth if there is not enough space for them to come through normally. Impacted wisdom teeth are still sometimes removed for orthodontic treatment, believing that they move the other teeth and cause crowding, ( some people say it is not true but it is and I know because my dad never got his wisdom teeth removed and it pushed his teeth around to where they crowded over each other) Impacted wisdom teeth may suffer from tooth decay if oral hygiene becomes more difficult or if someone just is not taking care of their teeth the way they should. Wisdom teeth which are partially pushed through the gum may also cause inflammation and infection in the surrounding gum tissues. Some more conservative treatments, such as operculectomes (forgot how to spell it), may be fitting for some cases, yet impacted wisdom teeth are commonly extracted as treatment for these problems, many times before these problems even occur.
hope this helps, if not I'm sorry