FDI tooth numbering
Also called: FDI notation, ISO 3950, two-digit tooth numbering
FDI tooth numbering is the two-digit system used in Canada and many other countries to identify teeth. The first digit is the quadrant of the mouth, and the second is the tooth’s position counting from the midline. Tooth 11 is the upper right central incisor, and tooth 36 is the lower left first molar.
How it shows up between practice and lab
The tooth number is the most basic fact on an Rx. A wrong digit sends the lab to the wrong tooth, or stops the case while someone checks.
Mix-ups come from other systems. Software or forms built for the United States may use Universal numbering, which gives the same tooth a different number.
A practice can prevent that by using FDI on every Rx, and saying so when it works with a lab outside Canada. A lab can confirm the system before it starts.
Read more in FDI tooth numbering on lab prescriptions and what to include on a dental lab prescription.
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