What numbering system is most commonly used in the United States for adult teeth?

• A. Palmer notation
• B. FDI two-digit system
• C. Zsigmondy notation
• D. Universal number system

Answer: (D)

The key idea is recognizing how dentists identify adult teeth in the United States. In this system, each adult tooth is given a single-digit number from 1 to 32. The sequence begins at the upper right third molar as tooth 1, moves across the upper arch to tooth 16, then drops down to the lower arch and continues to tooth 32 at the lower right third molar. This makes records, treatments, and communication straightforward because every tooth has one clear, consistent label across the entire mouth. For children, the primary teeth are labeled with letters A through T, which keeps the system organized when mixed dentitions are involved.

This approach is most common in US practice because it is easy to teach, quick to record, and aligns well with patient charts, treatment planning, and insurance documentation. Other systems exist, such as Palmer notation that combines quadrant markers with numbers, or the FDI two-digit system that uses a two-number code for quadrant and tooth, which is more common in other countries. Zsigmondy notation is largely historical and not widely used today.