FDI Tooth Numbering System: A Complete Guide for Dental Clinics

FDI (Fédération Dentaire Internationale) notation is the international standard for identifying teeth. If you're documenting dental treatment, submitting insurance claims, or communicating with labs, you need to use FDI notation correctly.

How FDI numbering works

Each tooth gets a two-digit number:

First digit = quadrant

• 1 = Upper right (maxillary right)
• 2 = Upper left (maxillary left)
• 3 = Lower left (mandibular left)
• 4 = Lower right (mandibular right)

Second digit = tooth position (1-8, counting from midline)

• 1 = Central incisor
• 2 = Lateral incisor
• 3 = Canine
• 4 = First premolar
• 5 = Second premolar
• 6 = First molar
• 7 = Second molar
• 8 = Third molar (wisdom tooth)

So tooth 36 = lower left first molar. Tooth 11 = upper right central incisor.

Deciduous (baby) teeth

For primary teeth, quadrants use 5-8:

• 5 = Upper right deciduous
• 6 = Upper left deciduous
• 7 = Lower left deciduous
• 8 = Lower right deciduous

Tooth 55 = upper right deciduous second molar.

Why FDI matters for your dental software

Your dental software should use FDI notation natively. If you have to mentally translate "upper right first molar" to "16" every time you write a record, your software is fighting you instead of helping you.

Good dental software:

• Shows FDI numbers on the tooth chart
• Lets you click a tooth to document conditions
• Links images and treatments to specific FDI numbers
• Uses FDI in billing codes and export files
• Handles both permanent and deciduous notation

FDI vs Universal vs Palmer

Three notation systems exist. FDI is the most widely used internationally. Know which one your clinic uses and make sure your software supports it.

• FDI: 36 = lower left first molar
• Universal: 19 = lower left first molar (US system)
• Palmer: └6 = lower left first molar

Most dental software supports FDI by default. Some US-focused systems use Universal. Check before buying.