Lesson 4: FDI Tooth Numbering

You will explore the internationally recognized two-digit standard used worldwide.

The FDI World Dental Federation notation assigns each tooth a two-digit code: the first digit identifies the quadrant (1–4 for permanent teeth, 5–8 for primary teeth), and the second digit identifies the tooth’s position counting from the midline. This system is used globally in research, education, and clinical documentation because it is unambiguous and universally standardized.