Wisdom tooth, commonly known as the third molar or akal jaad in hindi, is most commonly seen decayed tooth.
Unlike its name, it is not at all related to loss of wisdom. If the teeth are missing or have to be removed due to any reasons such as a cavity i.e. decay in the tooth or if the tooth is impacted i.e. stuck in the bone due to the small jaw size in most of the cases, there is no loss of wisdom at all. So, it is just a misnomer.
As the evolution is happening, the size of the human jaw is decreasing slowly. As these teeth are the last to erupt they do not get proper space to erupt. So, they end up either coming out in a direction where they do not help in chewing or are impacted i.e. remain inside the bone.
This leads to improper brushing in the region. There might also be a gap in between the second and the third molar where the food gets accumulated leading to cavity in both the teeth.