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Clear Aligner Basics
Glossary of Technical Terms
Glossary of Technical Terms
Michael Yoon avatar
Written by Michael Yoon
Updated over a week ago


The most popular form of alginate impression is supplied as a powder and mixed with water. Many alginate impressions changee color of the impression when the material is set.

At OrthoSnap,  we do not accept alginate impressions because they cannot keep an accurate form through delivery or any length of time. This is why we ask for PVS impressions instead. 

ANKYLOSED TOOTH: An ankylosed tooth is a tooth that has fused to the jaw. Normally, a tooth is separated from the jaw and can be moved by orthodontic treatments.  However, since the jaw has already attached to the tooth, movement is not available and the tooth's position is permanent.

ANTERIOR: Any of the front six teeth (the incisors and canines) in the upper or lower jaw. 

APEX: The end of the root of a tooth. 

BICUSPID: Two teeth between the canine and molar, typically having two cusps. These are also referred to as premolars.

BITE REGISTRATION. The bite, or dental occlusion, is the relationship between the lower and upper teeth when a patient bites down.

BRIDGE: A bridge is a false tooth or group of false teeth that are attached to a patient’s natural teeth. These are necessary when there is a missing tooth  for the purpose of closing the gap supporting the nearby teeth. Not doing so can damage the teeth surrounding the gap and potentially result in their loss. 

BUCCAL: The surface of the posterior teeth facing toward the cheek.

CANINE: The single tooth between the the lateral incisor and first premolar. 

CLASS I classification: This is a normal tooth relationship.  The teeth involved to determine this classification are the 1st molar and canines.  If the upper canine has a normal position to the lower canine and the 1st molar has a normal position to the lower 1st molar, then it can be said this is not a malocclusion.

CLASS I MALOCCLUSION: is where the canines and 1st molars have a relationship and the relationship also contains some imperfections.  These imperfections can included misalignment of the canines and/or 1st molars, any gaps, crowding and others.

CLASS II MALOCCLUSION: The next class of malocclusion is where the top molar and top canine relationships are incorrectly mesial (toward the front)  compared to a normal, Class I Occlusion. 

CLASS III: The next class of malocclusion is where the top molar and top canine relationships are incorrectly distal (toward the back) compared to a normal, Class I Occlusion. 

CONTRAINDICATE: A term that is used in dentistry and medicine, means one procedure or solution should not be combined with another. Certain medicines shouldn't be combined with alcohol, for example.  In dentistry, certain orthodontic procedures are not recommended with other existing conditions.

CROSSBITE: A common malocclusion type.  The main distinction of a crossbite is the lower incisors overlap the upper incisors.

CROWN: The part of a tooth attached to the tooth and typically outside the gums (or an artificial substitute for this). The term "clinical crown" refers to the visible portion of the tooth that a doctor can observe directly.

CROWN TIPPING: is the tilting of the crown of a tooth without moving the root. 

CUSP: The top of a tooth. Normally, the biting surface of specific teeth.

DENTAL IMPLANT: A dental implant is a fake tooth that is screwed into the jaw.  These are common when you lose a tooth.  With these, the patient benefits with easier eating and better support to the teeth that surrounded the gap that was once there.
DENTITION: Dentition refers to all of the teeth in the mouth. There are three categories.  The first is the baby teeth (deciduous) dentition.  The second is a "permanent" dentition; adult teeth.  The third is a "mixed" dentition; the mix of the first two.

DIASTEMA: A space between the two upper central incisor teeth. 

DISTAL: Can mean both moving the tooth away from the center of the mouth and the surface of the tooth that is facing the back of the mouth.

DISTALIZE: Moving the teeth away from the mid-line.  This is used for paletal expansion to provide space for tooth movements.

ENGAGER: Used when making difficult tooth movement, an engager meets and works with the tooth through a composite material. 

EXPAND: Refers to moving the teeth buccally to provide space between the teeth for difficult movements.

EXTRACT: The removing of a tooth.

EXTRUDE: To move the tooth away from the jaw and gum line.  Usually done in conjunction with horizontal attachments. 

To take a record of the patient's current occlusion, an impression is taken.  Pictured below is an impression, performed with the patient by a dentist of assistant.  To learn more, please visit:  How to Identify a Good Impression

The edge of incisors and canine that are used for biting.

Incisors are located on both arches; the front four on top and the front four on the bottom. Their function is for tearing and cutting into food. See below, #8 and #9 are named "central incisors" where #7 and #10 are named lateral incisors.

IPR (Interproximal Reduction): With IPR, a small space is created by reducing the proximal surface of a tooth. This is sometimes needed to create space needed for the teeth move to the desired position.  To learn more about IPR, see our article on IPRs (Interproximal Reduction)

INTRUDE: Intrusion is a tooth movement where a tooth is moved closer to the jaw bone. 

LINGUAL: This term refers to the tongue-side of the tooth. Additionally, lingual movement indicates movement of the tooth toward the tongue.

MACRODONTIA: this is a condition of the tooth that indicates teeth are larger than usual.  In turn, neighboring teeth or the whole mouth can be affected in various ways.

MALOCCLUSION: General term for teeth that aren't in a correct or normal position.

MANDIBLE: It is the lower jaw bone and contains the mandibular arch. See Below:

MAXILLA: The upper jaw bone and contains the maxillary arch. See Below:

MESIAL:  Can mean both moving the tooth toward the center of the mouth and the surface of the tooth that is facing the front of the mouth.


MICRODONTIA: this is a condition of the tooth that indicates teeth are smaller than usual.  In turn, neighboring teeth or the whole mouth can be affected in various ways.

MIDLINE: The midline is a point of reference to where identify various positions, movements, etc. This line is used for both upper and lower arches See Below: 

MOLAR: The back three teeth on each side of the mouth, for each arch. These teeth are used for chewing. See below for identification:

OCCLUDE: Occlude means to close the jaw. 

OCCLUSAL: The top surface of the premolars and molars, used to chew.

OCCLUSAL PLANE: The occlusal plane is the plane where the teeth on the lower and upper arch touch.  It's not necessarily a true plane and can vary.  A bite registration can depict the occlusal plane.

OCCLUSION: Occlusion is the relationship of the teeth of each arch when the jaw is closed.  

OSTEOBLAST: Osteoblasts are cells that create new bone. Once a clear aligner repositions the tooth through pressure. Osteoblasts will form new bone to stabilize the tooth in its new position.

OSTEOCLAST: Osteoclasts are cells that break down bone. In order for a clear aligner to reposition the tooth, the tooth is pressured into a new position with the service of osteoclasts. Once the osteoclasts break down the bone to make space for the tooth, the osteoblast forms new bone behind it.

OVERBITE: An overbite is when the upper anterior teeth cover the lower anterior teeth.

Overbite                                                               Normal Occlusion

OVERJET: Overjet is a maloclussion where the anterior teeth are projected over the lower anterior teeth; a popular term for this is buck teeth.

PALMER NOTATION NUMBERING SYSTEM: The Palmer notation is sometimes referred to as the “orthodontic numbering system”.

Palmer notation consists of a symbol (┘└ ┐┌) designating in the quadrant the tooth is found and the number or letter indicating which tooth. For example, the “left” and “right” refer to the patient’s left and right hand.

PERIODONTAL LIGAMENT: A periodontal ligament is the ligament that attaches the tooth to its housing jaw.

POSTERIOR: Posterior is a term used to explain something's relationship to the back of the body.  Molars, for example are called posteriors (opposite of anterior).  See below:

PREMOLAR : The teeth between the molar and canine, typically having two cusps and sometimes called a bicuspid.

ROTATE: In clear aligner therapy, you use rotation to mean the tooth surface is being repositioned but the center of the tooth stays in the same location.

ROOT: The part of the tooth that is the deepest and makes a connection with the jaw.


ROOT TIPPING: Tilting the root without moving the crown.

TORQUE: Torque is the force necessary to readjust the inclination of a tooth. 


TRANSLATE: This term means to move the tooth without changing it's inclination or orientation.

UNIVERSAL NUMBERING SYSTEM: The universal numbering system is used in the US and identifies specific teeth in the mouth by assigning a number or letter to it. 

Related Topics and Information:

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