To help you understand your dental report from Dr Colin Priestland, it is necessary for you to know how the Federation Dentaire Internationale (FDI) tooth numbering system works so you understand which tooth I am identifying when outlining your treatment plan in your report. It’s very simple as you will read below!
All teeth have a two number code. The first number refers to location in the mouth the tooth is located (top, bottom, left or right), and the second number identifies the tooth position with respect to the front and back of the mouth. The adult mouth is divided into 4 quarters referred to as quadrants. These are upper left (UL) and upper right (UR), and lower left (LL) and lower right (LR). The quadrants are numbered as follows: Upper right is quadrant 1, upper left is quadrant 2, lower left is quadrant 3 and lower right is quadrant 4. So starting upper right you progress around the mouth logically 1, 2, 3, and 4 for each quadrant.
Baby teeth known as deciduous teeth, are numbered as UR quadrant 5, UL quadrant 6, LL quadrant 7 and LR quadrant 8. There are only 5 deciduous teeth in each quadrant (2 incisors, one canine and two primary molars).
The adult human jaw should contain 8 teeth in each quadrant, made up of:
2 incisor teeth referred to as central incisor and lateral incisor (teeth 1 & 2), 1 canine tooth (tooth 3), 2 premolar teeth (teeth 4 & 5) referred to as the first and second premolars and finally 3 molar teeth referred to as the first, second and third molars (teeth 6, 7 and 8).
The last of these molars, the third molar, is also known as the wisdom tooth and in many cases the wisdom teeth have been removed and so many people have only 2 molar teeth remaining in each quadrant.
Tooth number examples:
Tooth numbers are spoken as follows: Tooth 11 is spoken as “tooth one one,” not tooth eleven. Tooth 23 is “tooth two three”, not tooth twenty three, an so on. Remember first number is the quadrant and the second number is where in the quadrant it is located.
FDI tooth 11: Quadrant 1 is upper right, and tooth number 1 is the tooth nearest the centre of the mouth this being the first of the incisor teeth known as the central incisor. Hence upper right central incisor.
FDI tooth 22: Quadrant 2 is upper left, and tooth number 2 is the second tooth from the centre being the “lateral” incisor tooth. Hence upper left lateral incisor.
FDI tooth 37: Quadrant 3 is lower left, tooth number 7 is the 7th tooth from the centre, known as the second molar tooth. Hence lower left second molar.
FDI tooth 45: Quadrant 4 is lower right, tooth number 5 is the 5th tooth from the centre or the second premolar tooth. Hence lower right second premolar.