Supernumerary Teeth Are Numbered Using the FDI or Universal Systems with Added Letters
Supernumerary (extra) teeth are typically numbered using modified versions of the FDI World Dental Federation or Universal Numbering System, with letters (e.g., "S" or "A/B") appended to standard tooth numbers. This ensures clarity in dental records while distinguishing them from primary/permanent teeth.
How Supernumerary Teeth Are Numbered
1. FDI (Two-Digit) System
- Standard teeth use quadrant + tooth number (e.g., "11" = upper right central incisor).
- Supernumerary teeth add a letter suffix:
- "S" (e.g., "11S" for a mesiodens near tooth 11).
- Or sequential letters ("A," "B") for multiple extras in one quadrant.
- Example: "23A" and "23B" for two supernumerary premolars in quadrant 2.
2. Universal Numbering System
- Permanent teeth: Numbers 1-32 (1 = upper right 3rd molar).
- Supernumerary teeth use:
- Numbers >32 (e.g., "33" for a mesiodens).
- Letters (e.g., "A," "B") after the nearest tooth number (e.g., "8A" for an extra near tooth 8).
3. Palmer Notation (Less Common)
- Uses symbols (⌵⌴⌶⌷) + tooth number.
- Supernumerary teeth may add a prime (′) (e.g., "⌵1′") or letter.
Comparison of Numbering Systems for Supernumerary Teeth
| System | Standard Teeth Format | Supernumerary Format | Example | Pros | Cons |
|---|---|---|---|---|---|
| FDI | Quadrant + tooth (e.g., "11") | Add "S" or "A/B" (e.g., "11S") | "24A" for extra near tooth 24 | Internationally standardized | Letters can confuse sequencing |
| Universal | Numbers 1-32 | Numbers >32 or letters (e.g., "8A") | "33" or "9B" for extras | Simple for U.S. practitioners | Limited to 26 letters (A-Z) |
| Palmer | Symbols + numbers (e.g., "⌵1") | Add prime (′) or letter (e.g., "⌴6′") | "⌶3A" for extra in quadrant 3 | Visual quadrant clarity | Rarely used for extras |
Key Considerations When Numbering
- Location: Number based on proximity to the nearest standard tooth.
- Type of Supernumerary:
- Mesiodens (between central incisors) → Often "1S/16S" (FDI) or "8A/9A" (Universal).
- Paramolar (near molars) → "6A" or "31" (Universal).
- Radiographs: Always confirm position via X-ray before assigning a number.
- Multiple Extras: Use sequential letters (A, B, C) to avoid ambiguity.
Common Mistakes to Avoid
- Skipping letters: Use "A," "B," "C" (not "A," "C") for multiple teeth in one area.
- Mixing systems: Stick to one system per patient record.
- Ignoring quadrants: In FDI, always note the quadrant (e.g., "35S," not just "5S").
- Overcomplicating: For a single extra, "11S" (FDI) or "33" (Universal) suffices-no need for "11S1."