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FDI Two-Digit Notation

The FDI World Dental Federation developed in 1971 a system to identify teeth with a number. This system is called the FDI Two-Digit Notation, also known as the ISO-3950 notation. The FDI Two-Digit Notation is widely recognised and used worldwide. It allows everyone on the oral health team to efficiently share information amongst themselves and further provides those outside the team with clear and precise information about their work. In addition, the FDI Two-Digit Notation is widely used to record information on a patient�s situation.

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Each patient�s mouth is divided into quadrants: upper-right, upper-left, lower-left and lower-right Left and right, as in all medicine notations, refer to the patient and not to the person visiting him/her. The quadrants are numbered from 1 to 4, in a clock-wise sense, starting from the upper-right.

Teeth are numbered from 1 to 8, going from the central incisor to the third molar. So the incisors are numbered 1 and 2 (11, 21, 12, 22, 31 �.), the canines are numbered 3 (13, 23, 33, 44) and the premolars 4 and 5 (14, 24, 45 �). All molars have a number ranging from 6 to 8 (16, 27, 48 �.).

For deciduous teeth, the system varies slightly. All child�s quadrants are numbered from 5 to 8, following the same starting point and rotation of the permanent numbering.

Please see the table below for a more detailed explanation.

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