Invisalign

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A

Aligner

One of a series of doctor-prescribed, custom manufactured, clear plastic removable orthodontic appliances. As the core of the Invisalign System, aligners gently move the patient's teeth in small increments from their original state to achieve a more nearly optimal state specified in the doctor's Invisalign treatment plan.

Andrews "six keys" to ideal occlusion

Described by Lawrence F Andrews; relates to an "ideal" rather than a "normal" occlusion.

Key I - Molar relationship: The distal surface of the disto-buccal cusp of the maxillary first permanent molar occludes with the mesial surface of the mesio-buccal cusp of the mandibular second permanent molar. The mesiobuccal cusp of the maxillary first permanent molar falls within the buccal groove between the mesial and middle cusps of the mandibular first permanent molar. (The canines and premolars exhibit a cusp-to-embrassure relationship buccally and a cusp-to-fossa relationship lingually).

Key II - Crown angulation: This key considers the mesio-distal angulation of the long axis of the clinical crown of each tooth, rather than the long axis of the entire tooth. The gingival portion of the long axis of each crown is distal to the occlusal (incisal) portion, the degree of mesiodistal crown angulation varies for each tooth type.

Key III - Crown Inclination: Crown inclination refers to the labiolingual or buccolingual inclination of the long axis of the crown, not to the inclination of the long axis of the entire tooth. The inclination of all the crowns has a consistent scheme:

• Incisors: Maxillary and mandibular incisor crowns are labially inclined to a degree sufficient to resist over eruption of their antagonists.

• Maxillary posterior teeth (canines to molars): A palatal (lingual) crown inclination exists, which is relatively constant from the canines through to second premolars and is slightly more pronounced in the molars.

• Mandibular posterior teeth (canines to molars): The crowns of the mandibular posterior teeth exhibit a lingual inclination that increases progressively from the canines to the second molars.

Key IV-Rotations: No rotations are present.

Key V-Spaces: There are no spaces; interdental contact points are tight.

Key VI-Occlusal plane: The sagittal plane of occlusion varies from flat to a slight curve of Spee.

CORRECT TOOTH SIZE: The "seventh key" to ideal occlusion

Bennett and McLaughlin described an additional key (seventh key) required for an "ideal" or normal dental occlusion relationship: correct tooth size.

The presence of a tooth size discrepancy between the maxillary and mandibular dental arches would otherwise result in either crowding or spacing, or compensatory angulations or inclination of the anterior teeth.

CORRECT TOOTH SIZE: The "seventh key" to ideal occlusion: in this example, the slightly small lateral incisor will need to be "built up" if the other keys are to be met.

Arch Shapes

Refers to the shape of the maxillary and mandibular arches.

There are three types of arch shapes found in the dental relationships:

1. Elliptical shape
2. Square shape
3. Tapering shape

B

Buccal Corridors

The negative space between the buccal surface of the maxillary first premolar and the inner point at which the lips join when the patient smiles.

C

Class I Malocclusion

In molar relation: The mesiobuccal cusp of the upper first molar occludes with the mesiobuccal groove of the lower first molar.

In canine relation: The mesial incline of the upper canine occludes with the distal incline of the lower canine whereas the distal incline of the upper canine occludes with mesial incline of the lower first premolar.

Class II division 1 malocclusion

In molar relation: Lower dental arch is distally positioned in relation to upper arch.The distobuccal cusp of the upper first permanent molar occludes with the mesiobuccal grooveof the lower first permanent molar.

In Class II canine relation: The distal incline of upper canine occludes with mesial incline oflower canines.

Class II division 1 subdivision

The condition where the class II molar relationship is unilateral or present only on one side with normal class I molar occlusion on the other side.

Class II division 1 Incisor relationship:

A) Class II division 1 incisor relationship with an increased overjet due to underlying Class II skeletal pattern with incisors of normal inclination.

B) Class II division 1 incisor relationship on a Class 1 skeletal pattern with an increased overjet due to proclined maxillary incisors and retroclined mandibular incisors.

Class II division 2 malocclusion

In molar relation: Lower dental arch is distally positioned in relation to upper arch. The distobuccal cusp of the upper first molar occludes with the mesiobuccal groove of the lower first molar.

In canines relation: The distal incline of the upper canine occludes with the mesial incline of the lower canine.

Class III malocclusion

In molar relation: The lower dental arch is in anterior relation to the maxillary arch. Mesiobuccal cusp of the upper first permanent molar occludes with the inter-dental space between the lower first and second permanent molars.

In canine relation: The upper canine occludes with the inter-dental space between lower first and second premolars.

Class III subdivision:

Condition in which class III molars relation is present only one side with normal relation on the other side.

Crossbite

1) An abnormal relationship of a tooth or teeth to the opposing teeth, in which normal buccolingual or labiolingual relationships are reversed.

2) Deviations from ideal occlusion in the transverse plane of space in the posterior and/or in the sagittal plane of space in the anterior

Crossbite Classification:

• Anterior or posterior
• Single tooth or groups of teeth
• Dental (result from faulty eruption pattern with no irregularity in the basal bone)
• or skeletal(results from irregularity in the basal bone)
• Unilateral or bilateral

Crowding classification ( mild, moderate and severe)

A condition in which the teeth are crowded in the dental arch, assuming altered positions, as by over-lapping and twisting.

D

Dental Camouflage

It is defined as implementation of a less intensive treatment plan option in a patient with a severe problem so as to obtain optimum results within physiologic limits and which may not be addressing the correction of the actually existing problem in the patient.

The goal of Dental camouflage is to disguise the unacceptable skeletal relationships by orthodontically repositioning the teeth in the jaws so that there is an acceptable dental occlusion and an esthetic facial appearance.

Dental Midline

There are two types of Dental Midline:

Maxillary Dental Midline: A line drawn perpendicular to the maxillary occlusal plane through the proximal contacts of the central incisors.

Mandibular Dental Midline: A line drawn perpendicular to the mandibular occlusal plane through the proximal contacts of the central incisors.

Distalization

Distalization is the technique that allows to selectively couple the teeth into ideal inter-digitation without the need for extracting permanent teeth. It is basically a process where teeth are sequentially moved backwards, starting with the second molar, so as to create space to do the following:

• Increase arch length
• Provides space to tidy up anterior crowding
• Decrease overjet and overbite
• Creates Class I molar and canine relationships
• Use in tandem with expansion, procline and IPR

Elastics are used in conjunction with the aligners.

E

Expansion

Enlargement; increase in volume, surface, or extent. The term is often used to refer to the process of widening the dental arches.

F

Facial Midline

A line drawn perpendicular to the inter-pupillary line from glabella to the tip of the nose, passing through the philtrum of the upper lip and the midline of the chin.

O

Overbite Measurement

To measure the vertical overlap of the upper teeth over the lower anterior teeth; usually refers to incisors.

Overjet Classification

To classify the Horizontal overlap of the upper and lower teeth; usually refers to incisors. In Class III malocclusion incisor overjet may be recorded as negative.

R

Retainer

An orthodontic appliance used to maintain tooth position and stabilize teeth following Orthodontic treatment. Vivera® retainers are clear thermoplastic retainers designed to be used after completing orthodontic treatment with Invisalign® or other orthodontic systems.

Root Torque

1.The rotation of a tooth along the long axis; moving the root of the tooth in a buccal or labial direction.

Rotation

Rotation can be defined as the spinning of the tooth around its long axis.

T

Translation

Translation of the tooth occurs when two forces are applied simultaneously to the crown of the tooth. In translation, crown and root move the same distance in the same direction. The applied force passes through the centre of resistance. Translation is of three types:

1. Bodily movement: This is the most desirable type of tooth movement. In bodily movement, crown and root move the same distance either lingually or labially.
2. Extrusion: Extrusion is defined as the axial movement of the tooth along the long axis towards the coronal part.
3. Intrusion:
   1. This is defined as the axial movement of the tooth along the long axis towards the apex of the root.
   2. Displacement of a tooth along its long axis into the alveolus.

Tipping

Tipping is the simplest tooth movement and the one easily carried out .In Tipping there is greater movement of the crown than that of the root.

There are two types of tipping: uncontrolled tipping and controlled tipping.

1. Uncontrolled tipping: Uncontrolled tipping is produced when a single force is applied to the crown of a tooth. Crown moves in one direction and the root moves in opposite direction.
2. Controlled tipping: This is the desirable tooth movement when compared to uncontrolled tipping. Crown moves in one direction and there is minimal or no movement of the root in opposite direction. Controlled tipping is useful in retraction of excessively incisors when roots are normally positioned.

Terms of direction in dental nomenclature:

Basic dental directions may be described in terms of orientation in relation to the teeth. The following terms may be used to describe both the tooth crown surfaces and directions of tooth movement.

• Mesial: this term means toward the dental midline, along the dental arch.
• Distal: this term means away from the dental midline, along the dental arch.
• Buccal( labial): this term means in the direction of the cheeks; it is ideally used for the posterior teeth but may be used as an inclusive term for both posterior and anterior teeth. The terms "labial" or "facial" mean in the direction of the lips; they are only used for the incisor teeth.
• Lingual (palatal): the term "lingual" means in the direction of the tongue; it also refers to the tooth surface facing the tongue. The term 'palatal''may be used when referring to the maxillary dentition.
• Apical: this term means toward the root apex.
• Occlusal (incisal): the term 'occlusal' means in the direction of the masticatory surfaces of the teeth. The term 'incisal' is the equivalent for the incisor teeth.

Terms of tooth position in the three planes of spaces:

The term bodily displacement refers to the malposition of the crown and root of a tooth in same direction and to a similar extent. The terms presented above may be used to described tooth position and/or malposition in the three planes of space:

• Sagittal (anteroposterior) plane: variations in the position of individual teeth in the sagittal plane may be termed labial/buccal or lingual/palatal bodily displacement.
• Vertical plane: variations in the position of individual teeth in the vertical plane may be termed Infraocclusion (excessively apically positioned) and supraeruption or overruption (excessively occlusally positioned).
• Transverse plane: variations in the position of incisor teeth in the transverse plane may be termed mesial or distal bodily displacement. Variations in the position of individual posterior teeth in transverse plane may be termed buccal or lingual/palatal bodily displacement.

Terms of bodily tooth movement in three planes of space:

The term translation may be defined as the movement of a body from one point of space to another such that every point of the body moves in the same direction and over the same distance, without any form of rotation or change in size. In dental nomenclature the term translation is synonymous with bodily tooth movement. The following terms may be used to describe bodily tooth movement in the three planes of space:

• Sagittal (anteroposterior) plane: bodily tooth movement(translation) in the labiolingual direction for incisors and the mesiodistal direction for the buccal segments is termed protraction (labial incisor movement or mesial buccal segment movement) and retraction (lingual/palatal incisor movement or distal buccal segment movement).
• Vertical plane: bodily tooth movement (translation) in the occlusal-apical direction is termed intrusion (apical movement) and extrusion (occlusal/incisal movement).
• Transverse plane: bodily incisor movement (translation) in the mesiodistal direction is termed mesial or distal bodily movement. Bodily movement of individual posterior teeth in the buccolingual direction is termed buccal or lingual/palatal bodily movement.

Terms of tooth rotation around the three axes of rotation:

The terminology used to describe the structural relationship of the teeth in relation to the three axes of rotation is as follows:

• Angulation: this term refers to the angular deviation of the long axis of the tooth from a line perpendicular to the occlusal plane, in the mesiodistal (labiolingual/buccolingual) axis (also termed second-order rotation0 leads to a change in its angulation.
• Inclination: this term refers to the angular deviation of the axis of a tooth from a line perpendicular to the occlusal plane in the labiolingual or buccolingual directions. Rotation of an incisor around the mesiodistal (transverse/horizontal) axis (also termed third-order rotation) leads to a change in its inclination.
• Proclination: refers to anterior (labial) inclination of the crowns of the incisor teeth.
• Retroclination: refers to lingual/palatal inclination of the crowns of the incisor teeth.
• Bodily rotation: this term refers to the rotation of a tooth around its long (occlusal-apical) axis. It is also termed first order rotation. Rotations are described according to the approximal surface of the tooth that is furthest from the line of the arch. e.g. a maxillary incisor may be mesio-or distolabially rotated or mesio- or distopalatally rotated.