What tooth number is the star on?

What tooth number is the star on?

• A. 18
• B. 3
• C. 9
• D. 21

Answer: (B)

In the universal tooth numbering system, teeth are numbered 1 through 32 starting at the upper-right third molar and moving across the upper arch to the left (1 to 8), then continuing on the lower arch from left to right (9 to 16 on the lower left, then 17 to 32 on the lower right). The star in the image sits on the upper-right first molar, which is the third tooth in that starting sequence. So its number is 3. The other options point to different teeth: 18 is the lower left second molar, 9 is the upper left central incisor, and 21 is the lower left first premolar.

In the universal tooth numbering system, teeth are numbered 1 through 32 starting at the upper-right third molar and moving across the upper arch to the left (1 to 8), then continuing on the lower arch from left to right (9 to 16 on the lower left, then 17 to 32 on the lower right). The star in the image sits on the upper-right first molar, which is the third tooth in that starting sequence. So its number is 3. The other options point to different teeth: 18 is the lower left second molar, 9 is the upper left central incisor, and 21 is the lower left first premolar.