During your regular dental checkup, you may have heard us say things like "15-MOD" or "3-buccal." It may sound like we're playing some bingo-like game with your mouth, but actually, we're using a kind of shorthand to quickly identify the surfaces of individual teeth. To help you decode our conversations, we'd like to share some of our "secret" language.

Deciphering the names of teeth

Children start out with 20 teeth, which begin to erupt in babies as young as 6 months old. These primary teeth eventually are replaced with several kinds of adult teeth, totaling 32 in all. Each kind performs specialized functions.

• Incisors: These 8 front teeth are good for biting because of their sharp edges.
• Cuspids: Also called "canine teeth" or "eye teeth," these 4 pointed teeth grasp and tear food.
• Bicuspids: Also called "premolars," these 8 teeth grind and mash food.
• Molars: These 12 large teeth, located in the most powerful part of the mouth, also grind and mash food. Molars are particularly efficient at making food soft enough to swallow.

Unlocking the numbers for teeth

Because there are several of each kind of tooth, using words to identify a single tooth would be time-consuming and potentially confusing. For example, having to refer to the "upper left lateral incisor" all the time would be a real mouthful.

This is why we use a numbering system to quickly identify each individual tooth. Instead of "upper left lateral incisor," we say "number 10." In the chart at right, you can see how we number teeth in the United States. In other countries, dentists often use different systems.

Decoding the outside surfaces of teeth

Each tooth has several surfaces, and we refer to each one separately when talking about the condition of your teeth. For example, a cavity might occur in just the biting surface or in the space where the sides of teeth meet. Similar to the numbering system for teeth, we use letters to refer to each tooth surface.

• "O" for occlusal: This refers to the top surface, which is colored red in the illustration at right.
• "M" for mesial (MEE-zee-ull): The mesial surface of the tooth, indicated in blue, is the side closest to the center of the mouth.
• "D" for distal: The distal surface, identified with yellow, is the side closest to the back of the mouth.
• Buccal (BUCK-ull): This is the cheek side of a tooth.
• Lingual: This is the tongue side of lower teeth.
• Palatal (PAL-ah-tal): This is the palate side of upper teeth.

Solving the puzzle

Now let's combine the codes and solve the puzzle. For example, if you hear us talk about decay in "15-MOD," what does that mean? The number 15 tooth is the upper left 2nd molar. Decoding the letters, you know that MOD stands for mesial, occlusal, and distal. This means that we've found decay on the biting surface of the upper left 2nd molar and that the decay reaches from the front to the back of the tooth. Let's hope this is just an example and not what we really find when we examine your teeth!