Kuwait Dental Board Orthodontics key terms

A line drawing made from a lateral skull radiograph in which bony landmarks and soft-tissue profile points are identified and connected, allowing angular and linear measurements to be compared against population norms.

The angle formed by sella, nasion and point A, expressing the anteroposterior position of the maxilla relative to the cranial base. A larger value suggests a more protrusive maxilla.

The angle formed by sella, nasion and point B, describing the anteroposterior position of the mandible relative to the cranial base. It is used to judge mandibular prognathism or retrognathism.

The difference between the SNA and SNB angles, indicating the anteroposterior skeletal relationship between maxilla and mandible. Positive values suggest a Class II tendency; negative values suggest Class III.

A cephalometric measure of jaw relationship obtained by projecting points A and B onto the functional occlusal plane and measuring the distance between them, reducing dependence on cranial base landmarks.

A reference plane drawn from porion to orbitale on a lateral cephalogram, used as a horizontal baseline for measuring facial heights, mandibular plane angle and incisor inclinations.

The angle between the mandibular lower border and a cranial reference plane such as Frankfort horizontal or the sella-nasion line. It reflects vertical facial pattern and the direction of mandibular growth.

A low-dose three-dimensional radiographic technique producing volumetric images of the jaws and teeth, used for impacted teeth, root position, airway assessment and planning of skeletal anchorage or orthognathic surgery.

The direction in which the mandible rotates during growth, described as forward (counterclockwise) or backward (clockwise). Forward rotation tends to deepen the bite and reduce lower face height.

The period of accelerated skeletal growth during adolescence, used to time functional appliance or growth-modification treatment. Its onset is estimated from standing height, hand-wrist radiographs or cervical vertebral maturation.

A method of estimating skeletal maturity from the shape of the second to fourth cervical vertebrae on a lateral cephalogram, used to decide whether growth modification is still feasible.

The difference in mesiodistal width between the primary canine and molars and their permanent successors in the same arch, space that can be used to relieve crowding during the transition to the permanent dentition.

The combined mesiodistal width of the primary second molar and first molar, which exceeds the width of the succeeding premolars. Its preservation or loss strongly influences crowding in the lower arch.

The difference between the space available along the dental arch and the space required by the teeth, calculated from study models or digital scans to quantify crowding or spacing.

A method of comparing the summed mesiodistal widths of the upper and lower teeth to detect interarch tooth-size discrepancy that could prevent ideal overjet and overbite despite correct alignment.

The horizontal distance between the incisal edge of the upper incisor and the labial surface of the lower incisor, measured parallel to the occlusal plane. It is a key measure of sagittal incisor relationship.

The vertical overlap of the upper incisors over the lower incisors, recorded in millimetres or as a percentage of lower incisor crown coverage. Deep or open bites guide treatment planning.

A validated scoring system combining a dental health component and an aesthetic component to grade malocclusion severity, widely used to prioritise access to publicly funded orthodontic care.

An occlusal index that scores displacement, overjet, overbite and centreline discrepancy before and after treatment, producing a weighted percentage improvement used to audit treatment outcome.

Resistance to unwanted tooth movement, provided by other teeth, the palate, the jaws or skeletal devices, allowing a force to move target teeth without displacing the reactive unit.

A small titanium screw or miniplate placed in bone to provide absolute anchorage for orthodontic forces, removing the need for patient cooperation and allowing movement of entire segments.

The point in a tooth or dental segment where a single force produces pure translation without rotation. Its location relative to the applied force determines the type of tooth movement produced.

The point about which a tooth appears to rotate during orthodontic movement. It lies at infinity for pure translation and within the root for tipping, depending on the moment-to-force ratio.

The ratio of the couple applied to a tooth to the single force acting on it, controlling whether movement is uncontrolled tipping, controlled tipping, translation or root torque.

A couple applied in the buccolingual plane that controls labiolingual inclination of a tooth, commonly expressed as the built-in twist of an archwire within a bracket slot.

The labiolingual angulation of an incisor relative to a reference plane, influencing profile, periodontal health and stability. It is assessed cephalometrically and controlled with torque during treatment.

A force magnitude that produces efficient tooth movement with minimal patient discomfort and minimal hyalinisation of the periodontal ligament, typically light and continuous rather than heavy and intermittent.

Degeneration of periodontal ligament fibres under excessive pressure, creating a cell-free zone that delays tooth movement until undermining resorption removes the compressed tissue.

Loss of root structure, usually apical, caused by orthodontic force, impaction, trauma or systemic factors. Severe cases are monitored radiographically and may limit force levels or treatment duration.

A fixed appliance system in which tip, torque and in-out values are built into the bracket prescription so that a plain archwire produces ideal tooth positions with minimal bending.

The planned progression from flexible nickel-titanium wires for alignment to stiffer stainless steel wires for space closure and finishing, matched to bracket slot size and treatment stage.

Sliding tooth movement along an archwire in which resistance between bracket and wire reduces the effective force delivered. It is contrasted with frictionless mechanics using loops or closing springs.

An equal and opposite force exerted by an appliance on the anchorage unit when a tooth is moved, explaining why anchorage loss occurs unless it is reinforced or eliminated.

A removable appliance that alters mandibular position or muscle activity to transmit growth-related forces to the dentition and jaws, typically used in growing patients with Class II malocclusion.

An extraoral appliance using cervical or occipital pull to restrain maxillary forward growth or retract upper teeth, requiring good patient cooperation and careful force control.

Treatment delivered during the mixed dentition to remove or reduce developing malocclusion, for example by space maintenance, serial extraction or correction of a crossbite or habit.

Surgical correction of jaw position, usually combined with orthodontic treatment, for skeletal discrepancies beyond the limits of growth modification or camouflage, planned from cephalometric and three-dimensional imaging.

An occlusal wafer fabricated from model surgery or digital planning that guides the jaws into their planned intraoperative position and is usually worn for a short postoperative period.

The thickness of gingival and alveolar tissue, described as thin or thick, which influences the risk of gingival recession and bone loss during orthodontic tooth movement.

The phase after active treatment in which appliances maintain tooth position while periodontal and occlusal tissues reorganise, reducing the likelihood of relapse.

Return of teeth towards their pretreatment positions after appliance removal, driven by periodontal fibre recoil, growth, soft-tissue pressure and failure to remove the original cause of malocclusion.

A bonded wire attached to the lingual surfaces of anterior teeth to hold alignment long term, requiring careful oral hygiene and periodic checks for bond failure or wire fracture.

Clinical decision-making that integrates the best available research evidence, clinician expertise and patient values, prioritising systematic reviews and randomised trials over anecdotal experience.