The International Tooth Numbering System (FDI)
- The first number identifies the quadrant
- The upper right is Quadrant #1
- The upper left is Quadrant #2
- The lower left is Quadrant #3
- The lower right is Quadrant #4
- Deciduous teeth (primary teeth) follow the same system: Quadrants #5, #6, #7, #8
- The second number identifies the tooth