Dentists need to communicate effectively and keep thorough records of which conditions affect which teeth, and dental notation systems help them do this. Whether in speech or in writing, dentists use a few different notation systems to record information that is associated with a specific tooth. The most widely used dental notation system in the United States is the Universal Numbering System. Internationally, dentists also use International Standards Organization Designation (ISO) Notation System, and the Palmer notation method.
In the 1940s, representatives from the American Dental Association (ADA) recommended that dentists use the Palmer notation method. This posed challenges with the increased use of keyboards, as the Palmer notation method uses symbols that are not found on traditional typewriter keyboards. Because of these challenges, the ADA changed its recommendation about 20 years later and began supporting the Universal Numbering System. In the mid-1990s, the ADA also began promoting the ISO Notation System as an additional notation option, in part due to the fact that the World Health Organization and the FDI World Dental Federation primarily use this ISO Notation System.
The ISO Notation System assigns a two-digit number to each tooth, based on the quadrant of the mouth where the tooth is located and the distance from the midline of the mouth. The first digit for the upper right front tooth is number 1, while the upper left front tooth is 2; the bottom teeth begin with 3 and 4, depending on the quadrant of the mouth. The second digit indicates distance from the midline; hence, the upper right front tooth is labeled “one, one,” as it is the first tooth in quadrant 1 of the mouth. The primary teeth, or baby teeth, are numbered differently, using the same quadrant numbers for the first digit but a different set of numbers to indicate the specific tooth.
The Palmer notation method continues to be widely used in the United Kingdom. The Palmer notation method uses a symbol to indicate the quadrant where the tooth is located, and a number to indicate which tooth is indicated. As with the ISO Notation System, the primary teeth are numbered differently than the adult teeth, though the quadrants are labeled the same way.
The Universal Numbering System is also called the American System. The Universal numbering System designates the right upper wisdom tooth as tooth 1, and the teeth are counted from there. If the wisdom teeth have been extracted or are otherwise absent, the space they occupy is still counted as tooth 1; the left upper wisdom tooth, or the space it would occupy, is tooth 16. The count continues with 17, the left lower wisdom tooth. The sequence is the same for primary teeth, but the system for primary teeth uses letters instead of numbers.
Other dental notation systems may be used by different populations; for example, paleoanthropologists that use a system that can apply to both humans and other animals. Some people use a modification of the Palmer notation method, called the alphanumeric system, which replaces the symbols used in the Palmer method with an abbreviation of the quadrant where the tooth is located; for example, teeth in the upper left quadrant are labeled “UL,” followed by the corresponding tooth’s number.