A to Z of Orthodontics


appliance – A general term used to describe any device used by an orthodontist, such as braces, retainer, biteplate, etc.

archwire – An archwire is a U-shaped piece of wire that is attached to the brackets on the teeth. The two main components of braces, which are normally visible, are the archwires and the brackets. The purpose of an archwire is to help shape the layout of the teeth into an optimal “arch” pattern. As teeth are moved with tensions and pressures, the archwire provides a guiding and shaping force to achieve the desired arch shape.


band – A band is a metal sleeve which is cemented to a tooth, usually a back molar, to provide an anchor point for the ends of the archwires.

banding – The process of fitting and attaching bands to the teeth.

bicuspid – Tooth with two points or cusps. There are two of these located between the cuspid and the molar in each quadrant of the mouth.

bionator – An orthopedic or “functional” appliance resembling a retainer. It is used to stimulate growth of the lower jaw in actively growing patients.

biteplate – An appliance similar to a retainer that is used to correct a deepbite or to help correct a crossbite.

bonding – The process of cementing brackets to the teeth.

bracket – Brackets are cemented to the teeth and provide a means to attach the archwire to each tooth. Elastics may also be attached to the brackets to create tension.


cephalometric X-ray – A large X-ray of the patient’s head. Usually taken from the side view, a cephalometric X-ray provides the orthodontist with information about how the patient’s teeth, jaw and soft tissue relate to each other.

clear braces – Refer to brackets made of a clear material. This helps to make the wearing of braces less noticeable.

crossbite – Exists when the relationship of one or more opposing teeth (upper and lower) is reversed, i.e. underbite.

crowding – Condition where teeth are too numerous or too large to fit into the existing jaw causing an overlap.

crozats – Also known as “removable braces”, these devices are similar to retainers in that they are not cemented to the teeth as traditional braces are, but can be snapped on and off in the same manner as retainers. The advantages of crozats are that they generally are less noticeable than traditional braces and that they can be removed completely for short periods of time. A disadvantage of crozats is that they can take longer to obtain the desired results.

cuspid – A tooth with a single point or cusp next to the front incisors. Sometimes called a canine tooth.


deepbite – A condition characterized by excessive overlapping of the upper and lower front teeth. Typically, anything more than a 20% overlap is considered a deepbite.


early intervention – Many orthodontic problems can be prevented or treated more easily if treatment is started at an early age. While the ages of six to ten are a typical starting point for a first phase of orthodontic treatment, some therapy may be appropriate for children as young as five years. Some intervention therapy has even been used successfully on children as young as three or four, although this is unusual. Early treatment, often called Phase I, is prescribed for young, growing children and is used to correct growth discrepancies between the two jaws, severe crowding of the teeth or crossbites of one or more teeth.

elastics – Elastics (rubber bands) that are attached to brackets, usually between upper and lower or front and back teeth, applying tension and causing teeth to move. Elastics can be used in many ways depending on the orthodontist’s treatment goals.

extraction – Surgical removal of one or more teeth to allow movement of remaining teeth. Usually done when teeth are crowded or in other cases where the presence of those teeth would interfere with optimal orthodontic treatment (see “crowding”).


headgear – An extraoral (outside of the mouth) appliance sometimes used to influence growth or move teeth, usually applied to the upper jaw. There are many different kinds of headgear, and your orthodontist can explain why a particular design may be appropriate for you.

Herbst appliance – A functional appliance used in some growing patients to stimulate growth of the lower jaw (mandible)


impression – A mould is used to make a plaster or stone model of your teeth.

incisor – A thin, flat tooth in the front of the mouth used for cutting and tearing.


jaw advancement – The process of moving a jaw forward, sometimes with the use of surgery.

jaw reduction – The process of moving a jaw backward, sometimes with the use of surgery.


labial – Refers to the lip side, or outside of the teeth.

lingual – Refers to the tongue side, or inner side of the teeth.

lingual braces – Braces that are attached to the tongue side, or inside of the teeth. The advantage of this is that the braces are not visible and are therefore cosmetically desirable, especially for adults. Disadvantages of this style of braces are that they are often difficult to work with and may interfere with clarity of speech in some cases.


malocclusion – An incorrect bite, meaning that the teeth do not fit together properly when the teeth are touching in a closed position.

mandible – lower jaw.

maxilla – upper jaw.

models – Stone or plaster replicas of the teeth and gums. These are used both for diagnostic purposes and for fabrication of some appliances like retainers and crozats.

molar – A large tooth towards the rear of the mouth, used for chewing and grinding food.


non-extraction – Treatment without the surgical removal of any teeth.


occlusion – The relationship of the maxillary and mandibular teeth.

openbite – A relationship in which the upper and lower teeth do not meet, for example, when there is a space between the upper and lower front teeth due to a thumb-sucking habit. Often these types of malocclusion have an underlying skeletal problem, and these bites can be very difficult to correct into functional contact without surgical assistance.

oral hygiene – Good oral hygiene is even more important when wearing braces. Failure to brush and floss properly while wearing braces can result in decay and disease of the teeth and gums, and even tooth loss. Although teeth may appear to be clean, it might not be.

overbite – The amount of vertical overlap of the upper and lower incisors (front teeth), usually expressed as a percentage.

overjet – The horizontal distance between the upper and lower incisor teeth, usually expressed in millimeters.


pendulum appliance – A device that is used to push back the upper molar teeth, sometimes used in cases of upper jaw crowding of the teeth or in cases that have excess overjet.


records – A set of diagnostic tools, usually consisting of X-rays, study models and photographs of the patient, depending on the case being treated.

relapse – Movement of the teeth back to their pre-treatment position following removal of braces at the completion of treatment. Interestingly, untreated individuals with perfect bite as teenagers often experience progressive crowding of the teeth throughout life. Retainers are routinely provided to patients following treatment to prevent relapse. Despite your orthodontist’s level of skill, a certain percentage of treated cases will relapse to some degree. Reasons for relapse are unclear at this point, so patients are often advised to continue wearing their retainers at night indefinitely, following a period of full-time wear.

retainer – A device that is worn full or part time to stabilize the teeth and prevent them from drifting or moving after treatment has been completed. Retainers are generally removable, but not always. Cooperation in prescribed retainer wear is very important in maintaining the results of orthodontic treatment after braces have been removed.


separators – Small wedges or circles of plastic or other material, which are inserted between teeth prior to banding, to temporarily increase spacing between teeth. This helps create the space needed to fit the bands over the teeth. They are generally removed at the banding appointment. Separators often create the feeling of having food stuck between your teeth while they are in your mouth.

space maintainer – An apparatus used to keep space for the erupting permanent teeth. Often recommended following the premature loss or extraction of a primary (baby) tooth.

spaces – Large gaps between teeth.


thermal (heat-activated) NiTi wire – These archwires are made of what is known as “memory metals”. Simply put, these metals tend to return to their original shape when they become warm. If you have ever seen the movie “Roswell”, a simulation of memory metals was done where a seemingly ordinary piece of aluminium foil was folded up and placed on a table. It quickly unfolded itself and returned to its flat condition with no traces of the folds. Memory metals have been used in many aerospace and industrial applications and are now being used in some state-of-the-art archwires. The wire can be bent in a cold or refrigerated state to adapt to teeth that are misaligned. Once in place, the warmth of the mouth will cause the archwire to return to its original shape, applying a spring-like tension to the teeth and causing movement into the desired arch pattern.

thumb sucking – Thumb sucking is a habit considered normal during infancy, but if prolonged, it can affect the growth of the upper and lower jaws. Typical results of thumb sucking include narrowing of the upper jaw, flaring or protrusion of the upper front teeth, anterior openbite, and reduction of or interference with the normal growth of the lower jaw. Opinions vary, but most orthodontists agree that thumb sucking should be stopped by age four. A persistent thumb-sucking habit can be corrected with the use of a simple orthodontic appliance.

ties – Ties can be elastic rings or wires. A bracket generally has a small, horizontal slot in which the archwire fits. Small wings on the bracket protrude on either side of the archwire. The archwire is seated in the bracket and then an elastic ring is slipped over the wings or a wire is wrapped around the wings to keep the archwire in the slot.

TMJ – Abbreviation for “temporo-mandibular joint”. This is the hinge point of the jaw and it can sometimes make a clicking or popping noise when a person chews or opens the mouth. If these symptoms are severe, or are accompanied by pain, it can sometimes be included in the orthodontic treatment plan.

tongue thrust – Habitual tongue thrusting against the teeth can cause problems with the teeth, causing them to move or shift out of alignment. A tongue thrust usually occurs during swallowing and can sometimes be detected by the presence of an anterior openbite. Tongue thrust habits can often be treated with the use of a simple orthodontic appliance. These habits are best treated early.

tooth positioner – A special retainer that can be used to fine-tune, or finish an orthodontic case that is nearly completed.


underbite – A malocclusion in which the upper incisor teeth are located behind the lower incisor teeth.


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