Iran Dental Specialty Board - Orthodontics key terms

The process of identifying and marking skeletal and dental landmarks on a lateral or posteroanterior radiograph so that angular and linear measurements can be calculated for diagnosis and treatment planning.

The angle formed by sella, nasion, and point A, expressing the anteroposterior position of the maxilla relative to the cranial base; a large value suggests maxillary protrusion.

The difference between the SNA and SNB angles, indicating the anteroposterior jaw relationship; positive values indicate a skeletal Class II tendency and negative values a Class III tendency.

A cephalometric measure of sagittal jaw discrepancy obtained by projecting points A and B onto the occlusal plane and measuring the distance between them, useful when the ANB angle is unreliable.

The technique of overlaying serial cephalometric tracings on stable cranial or mandibular structures to quantify growth, treatment change, and relapse over time.

The direction of mandibular rotation during growth, described as forward (counterclockwise) or backward (clockwise); it strongly influences chin projection, overbite, and the response to treatment.

The period of accelerated skeletal growth accompanying puberty, used to time orthopedic and functional treatment; its onset is estimated from statural, dental, and radiographic maturation indicators.

A method of estimating skeletal maturity from the shape of the cervical vertebrae on a lateral cephalogram, used to decide whether growth modification or orthognathic surgery is appropriate.

A removable or fixed device that alters mandibular posture or soft tissue forces to influence dentofacial growth and correct sagittal or vertical discrepancies, typically during active growth.

A fixed functional appliance using telescoping rods and tubes to hold the mandible forward continuously, producing skeletal and dental Class II correction during or after the growth spurt.

Separation of the midpalatal suture with heavy orthopedic force from a fixed expander, used to correct transverse maxillary deficiency and increase arch perimeter and nasal airway width.

A mismatch in width between the maxilla and mandible, commonly a narrow maxilla with posterior crossbite, assessed clinically and cephalometrically and treated by expansion or surgical widening.

Use of miniscrews, miniplates, or palatal implants as immobile anchors to move teeth without unwanted reciprocal movement, expanding the range of tooth movements possible.

The point in a tooth or tooth segment at which a single force produces pure translation without rotation; its location relative to the applied force determines the type of tooth movement.

The ratio of the applied couple to the applied force at the bracket, which determines whether a tooth tips, translates, or moves with controlled root torque.

Unwanted movement of the anchor teeth or segment in reaction to forces intended to move other teeth, reducing the planned correction and requiring anchorage reinforcement.

A force directed apically along the long axis of a tooth, ideally applied through the center of resistance; it is mechanically demanding and may cause root resorption if excessive.

Shortening of the root apex caused by sterile inflammation and odontoclast activity during orthodontic force application, influenced by force magnitude, duration, tooth type, and patient factors.

The combined supracrestal attachment of junctional epithelium and connective tissue above the alveolar bone crest; it constrains how far teeth can be intruded or moved toward the bone without gingival problems.

The coordinated resorption and formation of alveolar bone in response to orthodontic force, following the pressure-tension theory, that allows teeth to move through bone while maintaining attachment.

The resistance to sliding between archwire and bracket or tube, influenced by ligation, surface roughness, and angulation; excessive friction can slow space closure and consume anchorage.

A bracket with an integral clip or door that retains the archwire instead of elastomeric or wire ligatures, marketed for reduced friction and easier hygiene and adjustment.

The archwire stage that closes spaces, corrects root angulation, and finishes occlusion after initial alignment, typically using stiffer stainless steel or titanium-molybdenum alloy wires.

The built-in tip, torque, and in-out values machined into a bracket system, intended to produce a predetermined final tooth position without routine wire bends.

Sequential removable clear trays that move teeth through planned small increments, requiring good compliance, attachment placement, and careful staging of tooth movements.

The phase after active treatment in which appliances, such as fixed lingual wires or removable retainers, hold teeth in corrected positions while periodontal and occlusal adaptation occurs.

Post-treatment movement of teeth or jaws away from corrected positions, caused by periodontal fiber recoil, growth, occlusal forces, or inadequate retention.

Early treatment aimed at removing or reducing developing malocclusion, such as managing habits, correcting crossbites, or regaining space, before full fixed appliance therapy is indicated.

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

Comparison of available arch length with the space required for teeth, using study models or digital scans, to quantify crowding or spacing and guide extraction or expansion decisions.

A method comparing the summed mesiodistal widths of maxillary and mandibular teeth to detect interarch tooth size discrepancy, which can prevent ideal overjet and overbite finishing.

Surgical repositioning of the maxilla, mandible, or both, usually combined with orthodontics, to correct severe skeletal discrepancies that cannot be resolved by growth modification or tooth movement alone.

An acrylic wafer used during orthognathic surgery to establish the planned interocclusal relationship and stabilize the jaws while fixation is applied.

A group of conditions affecting the masticatory muscles and temporomandibular joints, producing pain, limited movement, or joint sounds; orthodontic treatment is neither a proven cause nor a proven cure.

A contact that deflects the mandible during closure or excursive movement, potentially causing instability, discomfort, or tooth wear; identified by careful articulation and occlusal analysis.

A ranking of study designs by susceptibility to bias, from systematic reviews and randomized trials at the top to case reports and expert opinion at the bottom, guiding clinical decision-making.

A prospective study in which participants are randomly allocated to interventions, minimizing selection bias and supporting causal inference about treatment effects.

Distortion of an observed exposure-outcome association by a third variable related to both, which must be addressed by design or statistical adjustment to avoid biased conclusions.

The ethical and legal process of disclosing diagnosis, treatment options, risks, benefits, and alternatives, including no treatment, so a competent patient can voluntarily agree.