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How Are Teeth Numbered?

How Are Teeth Numbered?


The 32 permanent adult human teeth are numbered, logically enough, by the numbers one through 32. The count starts at the top right, back side of the human mouth and runs counter-clockwise all along the top row of teeth till it reaches the number 16.

The bottom row of human teeth is numbered from that point onward, in the reverse direction. That is, starting at the bottom left back end of the mouth, the numbering continues with 17 and runs clockwise along the bottom row of teeth until it reaches the last back, right molar at 32.

Primary Teeth

Numbering schemes for teeth may vary from country to country, but in the U.S., the one used for a child’s primary set of 20 teeth is equally simple. Instead of numbers, letters of the alphabet are used, but it follows the same direction as the numbering scheme for adult teeth. Right to left, top, covers A to J; left to right, bottom, spans K to T.

Dentists also use complex numbering systems for the depth of a tooth’s root into the gum, the indentation of the top of the tooth surface, and so on. These numbering schemes are much more complex, as they have to cover a range of variations and factional differences from patient to patient.

World’s Oldest Human Teeth

The use of a universal teeth numbering charts and systems is a relatively modern phenomenon, closely tied to the advent of modern dentistry. But a number that is also worth pondering with regards to teeth is 400,000.

That’s how old eight human teeth recently found in Israel might be. Much speculation has ensured as to whether the teeth belonged to a Homo sapien, a Neanderthal or even third species of man. But while the location of these artifacts challenges some commonly held truths about the evolution of man, the number of teeth humans carry around in their mouths then and today remains a constant.


Dentistry 2000 – Human Teeth Numbering Charts, Retrieved February 1st, 2011 from

California Academy of Sciences – “400,000 Year Old Human Teeth?”, January 6, 2011, Retrieved February 1ast, 2011 from


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