Tooth numbering begins at the top-right of the mouth, called the upper maxillary jaw, according to Simple Steps to Dental Health, a website operated by Aetna. Numbering continues along the upper teeth and around to the opposite side before moving to the bottom row of teeth.
After dropping down to the bottom row of teeth, called the lower mandibular jaw, numbering starts on the left side of the mouth, say Simple Steps to Dental Health. Numbering then continues to the right lower side of the jaw. The number 1 tooth is the far upper-right tooth, while tooth number 32 is the far lower-right tooth.
The numbering of teeth for children who have not lost their baby teeth is slightly different, according to Simple Steps. Children typically have 20 primary teeth, also called baby teeth. Numbering goes in the same order as with adult teeth, starting at the upper right jaw and ending with the lower right jaw. However, there is a lower-case letter at the end of each number, such as 1d and 2d. The "d" stands for "deciduous," which is another word for the baby or primary tooth.
Some dentists use the Universal Numbering System for children, which uses letters instead of numbers, notes Simple Steps. Letters A through T are used in place of numbers 1 through 20, though the order of numbering the teeth is the same.