In the universal system of notation, the deciduous maxillary central incisors are designated by a letter written in uppercase.[2] The right deciduous maxillary central incisor is known as "E", and the left one is known as "F". The permanent maxillary central incisors are designated by a number. The right permanent maxillary central incisor is known as "8", and the left one is known as "9".[3]