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Guide to decoding your Orthodontist's lingo

Scrabble tiles

If you have been to the dentist or orthodontist, you have probably heard them rattle off fancy, sophisticated lingo when it comes to discussing your teeth and treatment. "Class II subdivision right with a bilateral crossbite of #s 4,5,6." What sort of weird language is this? Orthodontists use special, often abbreviated, vocabulary to communicate with their colleagues, assistants and staff.

To help you decipher this mysterious language, we have put together a crash course into what exactly we are saying...

Tooth numbering

Dentists and Orthodontists typically use separate tooth numbering systems. A person with a full set of adult teeth (including wisdom teeth) has 32 teeth. Dentists utilize tooth numbers starting at the top right (#1) and working around the mouth to the bottom right (#32).

As orthodontists, we number adult teeth by quadrants (upper right, upper left, lower right, lower left). Then, we number your teeth starting at the front and center. Your front tooth is number 1 and very back tooth (wisdom tooth) is number 8. Baby (primary) teeth are referenced in terms of letters instead of numbers (A through E). For example, adult canines are referred to as the "3's" and baby canines are referred to as the "C's."

Areas of your mouth and teeth

Buccal – front or cheek side

Lingual – back or tongue side

Mesial – towards the middle

Distal – towards the back

Gingival – towards the gums

Incisal/Occlusal – towards the biting surface of the tooth

Overbite and Overjet

These are two commonly confused dental terms. Overjet refers to the distance horizontally that the front teeth “jet” out in front of the lower teeth. Overbite, in orthodontic terms, refers to the vertical overlap between teeth.


Class I, II, or III refer to how upper and lower teeth fit together. Ideally, teeth come together in a Class I orientation, where upper and lower teeth fit like gears on a motor. Class II refers to when lower teeth are too far back compared to upper teeth. A Class III bite is more rare, and refers to when lower teeth are too far forward compared to upper teeth.

Braces parts

Brackets be braces bonded to your teeth that hold an archwire in place.

Archwire – the wire that moves your tooth into the desired place.

Elastics – rubber bands sometimes used to help fix your bite by shifting upper teeth or lower teeth.

Band – a metal band or ring that is bonded to a tooth.

Wire numbers

If you have braces, you’ll probably hear us refer to several numbers when we sit down to determine what wires we need to use. For example, "18x25 SS" or "16 NiTI." These numbers represent the sizes of the wires, and are measured in thousandths of an inch. So, when we refer to a 14 NiTI, this is actually a 0.014" round wire. In general, your treatment starts with small, light, flexible wires, and progresses to bigger wires that are stronger and allow us to move teeth or correct the bite better.

Wire types

There are specific types of wires we use for braces, and you'll often hear us refer to them in abbreviated terms such as NiTi, SS, and TMA.

NiTi stands for nickel-titanium. This is a flexible “shape memory” alloy that is usually used at the beginning of treatment to help unravel crowding. Some NiTi wires have the ability to respond to body temperature, meaning when you cool the wire it goes limp, and as it heats up to body temperature it retains its shape.

SS or “stainless” refers to stainless steel. This is a stiffer type of orthodontic wire, typically used to help correct overbite or used when we need to prescribe elastics/rubber bands to fix a bite.

TMA or “beta” refers to a titanium-molybdenum alloy. This is a slightly flexible, yet strong wire often used near the end of treatment to detail the final positions of teeth.


There are several ways of attaching orthodontic wires to the braces brackets. These include 1) “O” tie or single tie, 2) powerchain, and 3) steel tie. Single ties, or “O” ties, are most common. These are small elastic color ties that that wrap around the bracket to secure the wire. Power chain (often called PC for short) is used when we need to close spaces or prevent spaces from opening. It is essentially lots of small single ties linked together. Steel ties are used when we need to tie a wire tight, or prevent a tooth from moving in an undesired way.


Hopefully this guide helped you decipher the mysterious vocabulary of orthodontists! To help you practice your newly found decoding skills, here is a typical clinic conversation you might hear between Dr. Godley and her smile assistant…

Erica: Dr. Godley, we are in a 16 NiTi upper and lower. The LR3 is still slightly rotated.

Dr. Godley: Overall things are looking good. Let’s move up to a 17x25 NiTi upper with power chain, and 18 NiTI lower. Let’s also steel tie the LR3 to help fully align that tooth. We will see Sam back in 8 weeks, keep up the great work!


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