The maxillary third molar, commonly known as a wisdom tooth, is the tooth located laterally (away from the midline of the face) from both the maxillary second molars of the mouth with no tooth posterior to it in permanent teeth. In deciduous (baby) teeth, there is no maxillary third molar. The function of this molar is similar to that of all molars in regard to grinding being the principle action during mastication, commonly known as chewing. There are usually four cusps on maxillary molars, two on the buccal (side nearest the cheek) and two palatal (side nearest the palate). Nonetheless, for this tooth, there are great variances among third molars, and a specific description of a third molar will not hold true in all cases. It is important to note that the permanent maxillary molars are not considered to have any teeth that precede it. Despite being named molars, the deciduous molars are followed by permanent premolars.
In the universal system of notation, the permanent maxillary third molars are designated by a number. The right permanent maxillary third molar is known as "1", and the left one is known as "16". In the Palmer notation, a number is used in conjunction with a symbol designating in which quadrant the tooth is found. For this tooth, the left and right third molars would have the same number, "8", but the right one would have the symbol, "┘", underneath it, while the left one would have, "└". The international notation has a different numbering system than the previous two, and the right permanent maxillary third molar is known as "18", and the left one is known as "28".