Glossary of Orthodontic Terms


Active Treatment

The stage of orthodontic treatment is when teeth are being moved and/or jaws aligned.

Advanced periodontitis

The most severe form of gum (periodontal) disease. It is a chronic infection of the gums caused by accumulation of plaque under the gum line. The plaque contains bacteria that produce toxins that destroy the soft tissue and bone that hold teeth in place. Pockets (spaces between the gum and the teeth) appear and deepen. Gums recede, and bone dissolves. Teeth can become loose and may have to be removed.


Clear, thin, removable trays that are formed to fit an individual’s teeth and are used to straighten teeth. Patients are responsible for insertion and removal.





Any device used by an orthodontist, attached to the teeth or removable, designed to move the teeth, change the position of the jaw, or hold the teeth.


Upper or lower jaw. The “dental arch.”


The metal wire that is attached to the braces and used to move the teeth.


The tooth-colored “bumps” are placed on teeth during clear aligner treatment.  They help move the teeth while a patient wears aligners. They are removed once treatment is complete.



A metal ring, usually on a back tooth, that is cemented to a tooth for strength and anchorage.


How top and bottom teeth come together. Ideally, each tooth meets its opposite tooth in a way that promotes functions such as biting, chewing and speaking. A bad bite is called a malocclusion. The goal of orthodontic treatment is to create an individualized healthy bite (ability to bite, chew, speak). Additionally, when teeth and jaws are in proper positions, it creates a pleasing appearance.


A word commonly used to describe a fixed orthodontic appliance, usually consisting of brackets, bands and wires.


The small metal, ceramic, or plastic attachment is bonded to each tooth with a tooth-colored adhesive. The bracket has a slot that the orthodontic wire fits into.  Also known as a “brace.”


A replacement for a missing natural tooth/teeth that fills the opening between adjacent teeth. Most often, the existing adjacent teeth receive crowns and a prosthetic (false) tooth is attached to the crowns. This restores function, provides a good appearance, and maintains the shape of the face. Bridges do not last forever, eventually this will require replacement.


Brushing the teeth is part of an individual’s daily home dental care.  Patients with braces should follow the orthodontist’s instruction on how often to brush.


Grinding of the teeth, usually during sleep.  Bruxism can cause abnormal tooth wear and may lead to pain in the jaw joints, facial and/or neck muscles and difficulty opening and closing the mouth.


A term orthodontists use to describe the cheek side of the back teeth in both jaws.

Buccal Tube

A small metal part of the bracket is welded to the cheek side of the molar band. The tube may hold an archwire, lip bumper, headgear, facebow or other type of appliance an orthodontist may use to move the teeth.


Cephalometric Radiograph

A side view x-ray of the head.


A stretchable series of elastic o-rings connected together and placed around each bracket to hold the archwire in place and close the spaces between teeth.  Also known as a “power chain.”

Class I Malocclusion

A malocclusion in which the back molars meet properly, but the front teeth may appear to be crowded together or spaced apart.  There may be an overbite, an openbite, a posterior (back) crossbite or an anterior (front) crossbite with a Class I Malocclusion.

Class II Malocclusion

A malocclusion the lower teeth and/or jaw is positioned back relative to the upper teeth and/or jaw.  This results the upper front teeth protruding forward.

Class III Malocclusion

A malocclusion where the lower teeth and/or jaw is positioned ahead relative to the upper teeth and/or jaw.

Closed Bite/Deep Bite

Also known as deep overbite, this occurs when the upper front teeth overlap the bottom front teeth an excessive amount.

Comprehensive Treatment

Complete orthodontic treatment is performed to correct a malocclusion.

Cone Beam CT/CBCT

A 3D x-ray.

Congenitally Missing Teeth

A genetic occurrence in which permanent teeth do not develop.


Upper back teeth are in crossbite if they erupt and contact inside or outside of the lower back teeth. Lower front teeth are in crossbite if they erupt in front of the upper front teeth. A crossbite can be a single tooth or groups of teeth.


The part of the tooth that is visible above the gums;  OR, A tooth restoration placed by a dentist. A crown restoration covers a tooth that may have had severe decay, was badly discolored, or was broken or otherwise misshapen. The crown covers the entire tooth and functions as a replacement for the natural tooth. Crowns placed by dentists can last for many years, but they are not permanent.




White marks on the teeth that can become cavities in the future. They are caused by poor brushing, and the consumption of sugary and acidic drinks.


Diagnostic Records

The materials and information that the orthodontist needs to properly diagnose a malocclusion and plan a patient’s treatment. Diagnostic records may include a thorough patient health history, a visual examination of the teeth and supporting structures, an electronic scan or plaster models of the teeth, extraoral and intraoral photographs, as well as a panoramic and cephalometric x-rays.


Ectopic Eruption

Term used to describe a tooth or teeth that erupt in an abnormal position.


Rubber bands.  During certain stages of treatment, small elastics or rubber bands are worn to provide individual tooth movement or jaw alignment.


The hard, white outer layer of a tooth, and the hardest substance in the human body. Enamel makes it possible to bite and chew. If enamel breaks away from a tooth, or is worn away due to abnormal forces generated by a bad bite (or malocclusion), it is gone forever. Enamel does not regenerate.


The process by which teeth enter into the mouth.

Essix Retainer

A removable retainer made of a clear, plastic-like material.


An orthodontic appliance that can widen the jaws.


The removal of a tooth.

Extraoral Photographs

Photographs taken of the face from the front and side views.



An orthodontic appliance worn with orthodontic headgear, used primarily to move the upper first molars back, creating room for crowded or protrusive front teeth. The facebow has an internal wire bow and an external wire bow.

Fixed Appliances

An orthodontic appliance that is bonded or cemented to the teeth and cannot be or should not be removed by the patient.


An important part of daily home dental care. Flossing removes plaque and food debris from between the teeth, brackets and wires. Flossing keeps teeth and gums clean and healthy during orthodontic treatment.

Forsus Spring

An orthodontic appliance made of a fixed spring mechanism that moves the lower jaw forward, usually to correct an overjet (protruding upper teeth). It can also be used as an anchor for other types of movements.


The tissue attachment between the lip and the tongue or the lip and the upper jaw. A large frenum can cause spacing between the front teeth or cause the tongue to be “tied.” A large frenum can also cause the gum tissue on the lower front teeth to be pulled down.


The surgical removal or repositioning of the frenum.


Refers to biting, chewing and speaking. Teeth and jaws in their correct positions facilitate proper function.

Functional Appliances

A type of orthodontic appliance that uses jaw movement and muscle action to place selective force on the teeth and jaws. They are usually removable. They are also known as orthopedic appliances with names such as orthopedic corrector, activator, bionator, Frankel, Herbst or twin block appliances.



Soft tissue around the teeth, also known as the gums.


The mildest type of gum (periodontal) disease, usually caused by poor dental hygiene that allows a build-up of plaque and subsequent inflammation in the gums . Symptoms include red and/or swollen gums, and bleeding when you brush or floss. Gingivitis can be reversed with professional treatment and good dental care at home. If left untreated it may progress to periodontitis.

Growth Modification

Placing braces or appliances to help modify and correct the growth of the jaws and teeth.

Gum disease

Another name for periodontitis. A chronic infection of the gums that stems from a build-up of plaque (link to glossary). Also called periodontal disease. Untreated gum disease can lead to tooth loss. Patients having orthodontic treatment need to remove plaque frequently by brushing their teeth after meals/snacks and before bed, and by flossing at least once a day. There are three stages of gum disease: gingivitis, periodontitis and advanced periodontitis. Many people are unaware that they have gum disease because there is little or no pain.

Gummy Smile

Showing an excessive amount of gingival (gum) tissue above the front teeth when smiling.


Hawley Retainer

A removable retainer made of wire and a hard plastic-like material.


An appliance worn outside of the mouth to provide traction for growth modification and tooth movement.

Holding/Lingual Arch

Bands on the upper or lower molars are connected using a bar behind teeth; used to maintain space.



A tooth that does not erupt into the mouth or only erupts partially is considered impacted.


An artificial replacement for a missing tooth/teeth. The process involves placing a metal post in the jawbone. A crown is placed on the implant so that the patient is able to bite, chew and speak. Implants can be used to anchor a single tooth or multiple teeth. An orthodontist can create space or hold space open in the mouths of patients who may need implants to achieve good dental function. Dental implants cannot be moved by conventional orthodontic forces.

Interceptive Treatment

Orthodontic treatment is performed to intercept or correct a developing problem. Usually performed on younger patients that have a mixture of primary (baby) teeth and permanent teeth. Sometimes called Preventive or Phase I treatment.

Intraoral Photographs

Photographs taken of the inside of the mouth, usually showing the biting surfaces of the teeth and sides of the mouth while biting down.

Interproximal Brush

A tiny brush used to reach between teeth, and between teeth and braces, to remove plaque and food debris.

Interproximal Reduction

Removal of a small amount of enamel from between the teeth to reduce their width. Also known as reproximation, slenderizing, stripping, polishing, enamel reduction or selective reduction.



The surface of the teeth in both jaws that faces the lips.

Ligating Modules

A small elastic o-ring, shaped like a donut, used to hold the archwire in the bracket. Also called “o-rings” or “o-ties.”


A tiny rubber band, or sometimes a very thin wire, that holds the orthodontic wire in the bracket slot/brace.


The tongue side of the teeth in both jaws.

Lip Bumper

An orthodontic appliance used to move the lower molars back and the lower front teeth forward, creating room for crowded front teeth. The lower lip muscles apply pressure to the bumper creating a force that moves the molars back.

Lip Incompetence

The inability to close the lips together at rest, usually due to protrusive front teeth or an excessively long face.



Latin for “bad bite.” The term used in orthodontics to describe teeth that do not fit together properly.


The lower jaw.


The upper jaw.

Mixed Dentition

The dental developmental stage in children (approximately ages 6-12) when they have a mix of primary (baby) and permanent teeth.


A removable device used to protect the teeth and mouth from injury caused by sporting activities. The use of a mouthguard is especially important for orthodontic patients.



A removable appliance worn at night to help an individual minimize the damage or wear that occurs while clenching or grinding teeth during sleep.



Latin for “bite.” In orthodontics, occlusion describes how the upper and lower teeth meet.

Open Bite

A malocclusion in which teeth do not make contact with each other. With an anterior open bite, the front teeth do not touch when the back teeth are closed together. With a posterior open bite, the back teeth do not touch when the front teeth are closed together.


A tiny, o-shaped rubber band that is used as a ligature and holds the archwire to bracket slots. O-rings come in a variety of colors, and are generally changed at each adjustment appointment.


The specialty area of dentistry concerned with the diagnosis, supervision, guidance and correction of malocclusions. The formal name of the specialty is orthodontics and dentofacial orthopedics.


Orthognathic surgery

Also called surgical orthodontics, orthognathic surgery is corrective jaw surgery performed to remedy skeletal problems that affect the ability to bite, chew and speak. Orthodontic treatment is done before and after surgery so that upper and lower teeth meet appropriately.

Orthopedic Appliance

A removable functional appliance designed to guide the growth of the jaws and face.


The upper front teeth excessively overlap the bottom front teeth when back teeth are closed. Also called a closed bite or deep bite.


The upper front teeth protrude in front of the bottom front teeth when back teeth are closed.  Sometimes called buck teeth.


Panoramic Radiograph

An x-ray that shows all the teeth and both jaws at once.

Palatal Expander

A fixed or removable orthodontic appliance used to make the upper jaw wider.

Periodontal Disease

A chronic infection of the gums and jaw bones that stems from a build-up of plaque; many times there is little or no pain. Untreated  periodontal disease can lead to tooth loss. There are three stages of periodontal disease: gingivitis, periodontitis and advanced periodontitis.

Periodontal Tissue

Refers to the hard and soft tissue, or supporting structures, around the teeth.


A more serious form of gum (periodontal) disease as compared to gingivitis. It is a chronic infection caused by an accumulation of plaque under the gum line. The bacteria in plaque produce toxins that lead to destruction of the soft tissue and bone that hold teeth in place. Pockets (spaces between the gum and the teeth) form.  Unless treated professionally in conjunction with careful home care, the disease process will continue to break down tissues.

Phase One (Phase I) Treatment

Orthodontic treatment performed to intercept or correct a developing problem. Usually performed on younger patients that have a mixture of primary (baby) teeth and permanent teeth. Sometimes called Preventive or Interceptive treatment.


Plaque is a colorless, sticky film which is a mixture of bacteria, food particles and saliva that constantly forms in the mouth.  Plaque combines with sugars to form an acid that endangers teeth and gums. Plaque causes cavities, white marks (decalcification) and gum disease. Plaque is removed by brushing and flossing.



Power chain

Interconnected elastic ligatures that are stretched across multiple teeth, holding the archwire to bracket slots. Orthodontists use power chains for some patients during specific times during their treatment to apply additional forces to move teeth.

Preventive Treatment

Orthodontic treatment to prevent or reduce the severity of a developing malocclusion (bad bite). Also called Interceptive or Phase I treatment.

Primary Teeth

Baby teeth. Also called deciduous or milk teeth.



Also called an x-ray, a radiograph is a diagnostic tool that is used to see inside the body. Orthodontists take panoramic radiographs to see a complete horizontal image of a patient’s upper and lower teeth. A cephalometric radiograph is a side view of a patient’s head.

Removable Appliance

An orthodontic appliance that can be removed from the mouth by the patient. Removable appliances are used to move teeth, align jaws and/or to keep teeth in their new positions when the braces are removed (retainers).


A fixed or removable appliance worn after braces are removed or aligner therapy is complete. A retainer is fitted to upper and/or lower teeth to hold them in their finished positions. When worn as prescribed, retainers are the best tool available to minimize unwanted tooth movement after active treatment ends.

Rubber Bands

During certain stages of treatment, small elastics (rubber bands) are worn to provide individual tooth movement or jaw alignment.



An elastic o-ring or small wire loop is placed between the teeth to create space for placement of orthodontic bands. Separators are usually placed between the teeth a week before bands are scheduled to be placed on the teeth.

Self-Ligating Brackets

Brackets that have a “door” on the front that holds the orthodontic wire to the bracket. With self-ligating brackets, an elastic ring is not needed to hold the orthodontic wire to the bracket.

Serial Extraction

Selective or guided removal of certain primary (baby) teeth and/or permanent teeth over a period of time to create room, reduce crowding and create a better environment for the permanent teeth to erupt.

Skeletal maturity

A time when an individual has stopped growing, and bones have reached their full development.


Tiny elastics (rubber bands) that are inserted between molars. Spacers are placed one or two weeks before getting braces to create space between molars if molar bands will be used as part of the orthodontic appliance. Occasionally,  spacers fall out before braces are placed.

Space Maintainer

A fixed appliance used to hold space for an unerupted permanent tooth after a primary (baby) tooth has been lost prematurely, due to accident or decay.


Supernumerary Teeth

An occurrence in which there are more teeth than the usual number. These teeth can be malformed or erupt abnormally. These teeth can also interfere with the normal pattern of tooth eruption and contribute to an orthodontic problem. Supernumerary teeth often need to be removed.


Temporary Anchorage Device (TAD)

A miniature surgical screw that resembles an earring stud when it is in place. Positioned in gum and bone tissue, a TAD is used as an anchor – a fixed point from which to apply the force needed to move teeth in a direction that braces alone cannot move them. The TAD is removed when it is no longer needed.

Tongue Crib

A fixed orthodontic appliance used to help a patient stop habits or undesirable tongue forces exerted on the teeth and bone that supports the teeth.

Tongue Thrust

A habit where an individual’s tongue pushes against the teeth when swallowing.  This type of force generated by the tongue can move the teeth and bone and may lead to an anterior or posterior open bite.



The lower front teeth or jaw sit ahead of the upper front teeth or jaw. Also known as a Class III malocclusion.



A thin, tooth-colored shell that is glued to the fronts of teeth to improve their appearance. A veneer can cover up a discolored or broken tooth. Veneers cannot correct malocclusions (misaligned teeth and/or jaws). However, veneers can be easier to place and last longer after an individual has had orthodontic treatment and teeth are properly positioned.



Orthodontic wax is placed on the brackets or archwires to prevent them from irritating the lips or cheeks.


Also known as archwires, they are held to brackets using small elastic o-rings (rubber bands), stainless steel wire ligatures, or by a door on a self-ligating bracket. Wires are used to move the teeth.



Also called a radiograph, an x-ray is a diagnostic tool that is used to see inside the body. Orthodontists take panoramic x-rays to see a complete horizontal image of a patient’s upper and lower teeth. A cephalometric x-ray is a side view of a patient’s head.