Extracted wisdom tooth. Close-up of an upper wisdom tooth that has been extracted from a patient's jaw and gum. Brown, hardened dental plaque, known as tartar, has built up around the gum line. Wisdom teeth are the third and last set of molars to emerge in the mouth. In many cases wisdom teeth are unable to emerge fully from the gum due to lack of available space. This may cause severe pain and often results in their removal.