Dental professionals, in writing or speech, use several different dental notation systems for associating information with a specific tooth. The three most common systems are the ISO System (ISO 3950, the FDI World Dental Federation notation), Universal Numbering System, and Palmer notation method. The ISO system is used worldwide, and the Universal is used widely in the United States. The ISO System can be easily adapted to computerized charting.ISO notation upper jawISO notation lower jawISO notation primary teeth Dental professionals, in writing or speech, use several different dental notation systems for associating information with a specific tooth. The three most common systems are the ISO System (ISO 3950, the FDI World Dental Federation notation), Universal Numbering System, and Palmer notation method. The ISO system is used worldwide, and the Universal is used widely in the United States. The ISO System can be easily adapted to computerized charting. Another system is used by paleoanthropologists. A committee of the American Dental Association (ADA) recommended the use of the Palmer notation method in 1947. Since this method required the use of symbols, its use was difficult on keyboards. As a result, the association officially supported the Universal system in 1968. The World Health Organization and the Fédération Dentaire Internationale officially uses the two-digit numbering system of the FDI system. However, in 1996, the ADA adopted the ISO System as an alternative to the Universal System. The International Standards Organization Designation System (ISO System) by the World Health Organization notation system is widely used by dental professionals internationally to associate information with a specific tooth. Based on the Fédération Dentaire Internationale (FDI), it is also known as ISO 3950 notation. Thus the ISO System uses a two-digit numbering system in which the first digit represents a tooth's quadrant and the second digit represents the number of the tooth from the midline of the face. For permanent teeth, the upper right teeth begin with the number, '1'. The upper left teeth begin with the number, '2'. The lower left teeth begin with the number, '3'. The lower right teeth begin with the number, '4'. For primary teeth, the sequence of numbers goes 5, 6, 7, and 8 for the teeth in the upper right, upper left, lower left, and lower right respectively. When speaking about a certain tooth such as the permanent maxillary central incisor, the notation is pronounced “one, one”. Beware of mixing up the teeth in written form such as 11, 12, 13, 14, 15, 16, 17, 18 between the Universal and ISO systems.