Kuwait Dental Board Orthodontics flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Cephalocaudal gradient

The principle that growth proceeds from head to foot, so the craniofacial complex matures earlier than the trunk and limbs; neural growth peaks earliest and lymphoid tissue last.

Scammon's growth curves

Four tissue-specific growth curves: neural (early), general somatic (intermediate), genital (pubertal), and lymphoid (overshoots to about 200% then involutes). They predict when craniofacial structures grow most.

Spheno-occipital synchondrosis

An endochondral growth center at the cranial base that contributes to anteroposterior cranial base growth and typically fuses between roughly 12 and 15 years of age.

Cervical vertebral maturation

A method of assessing skeletal maturity from lateral cephalogram changes in the C2-C4 vertebral bodies; stages CS3 and CS4 indicate the acceleration and peak of the pubertal growth spurt.

Leeway space

The difference between the combined mesiodistal widths of the primary canine and molars and their permanent successors; about 1.5 mm per side in the mandible and 0.9 mm per side in the maxilla.

ANB angle

The angle between the A-point, nasion, and B-point lines; it indicates the anteroposterior jaw relationship, averaging about 2 degrees, with higher values suggesting Class II and lower values Class III.

Wits appraisal

A cephalometric measure that projects A-point and B-point onto the functional occlusal plane; it assesses jaw discrepancy with less influence from cranial base variation than ANB.

IOTN

The Index of Orthodontic Treatment Need combines a dental health component graded 1-5 with an aesthetic component scored 1-10; grades 4-5 or aesthetic scores 8-10 indicate definite treatment need.

PAR index

The Peer Assessment Rating index scores alignment, overjet, overbite, buccal occlusion, and midline to quantify malocclusion severity and treatment outcome; a reduction of about 30% or more indicates meaningful improvement.

Bolton anterior ratio

The ratio of the sum of mandibular six anterior tooth widths to the maxillary six, with a mean near 77.2%; deviation indicates anterior tooth-size discrepancy requiring interproximal reduction or restorative correction.

Tanaka-Johnston analysis

A mixed dentition space analysis predicting unerupted canine and premolar widths as half the width of the four mandibular incisors plus 10.5 mm per side in the mandible and 11.0 mm per side in the maxilla.

SLOB rule

Same Lingual, Opposite Buccal: on two periapical views taken at different tube angulations, the object that moves in the same direction as the tube is lingual, localizing impacted canines.

Downs facial angle

A cephalometric angle between the Frankfort horizontal and the facial plane (nasion to pogonion), averaging about 87 degrees; it describes the anteroposterior position of the chin.

Tweed triangle

A cephalometric triangle using the Frankfort-mandibular plane angle (about 25 degrees), IMPA (about 90 degrees), and FMIA (about 65 degrees); FMIA is the primary diagnostic angle.

Ricketts E-line

The esthetic line from the tip of the nose to soft tissue pogonion; in adults the lower lip should lie about 2 mm behind this line for a balanced profile.

Center of resistance

The point in a tooth through which a force must pass to produce pure translation; for a single-rooted tooth it lies about one-third of the root length from the alveolar crest.

Moment-to-force ratio

The ratio of applied moment to force that determines tooth movement type: low ratios produce tipping, intermediate ratios controlled tipping, and high ratios translation or root torque.

Pressure-tension theory

The theory that orthodontic tooth movement is driven by altered vascular pressure in the periodontal ligament, producing bone resorption on the pressure side and apposition on the tension side.

Hyalinization

Degeneration of the periodontal ligament under heavy continuous force; movement is delayed until undermining resorption removes the compressed bone, so lighter forces are more efficient.

Wire stiffness rule

Archwire stiffness increases with the fourth power of diameter, so doubling the diameter increases stiffness about sixteen times; this governs the gradual progression of archwire sizes.

Beta-titanium wire

A titanium-molybdenum alloy with a modulus roughly 40% that of stainless steel, giving a wide working range; used for finishing arches and auxiliary springs requiring light, controlled force.

Adams clasp

A removable appliance retainer with two arrowheads that engage about 0.5 mm of mesial and distal undercut on a premolar or molar, providing reliable clasp retention.

Twin block appliance

A two-piece functional appliance with upper and lower acrylic blocks and interlocking inclined planes that posture the mandible forward; worn full time, including during meals, for Class II correction.

Rapid maxillary expansion

Separation of the midpalatal suture using heavy forces, often about 0.5 mm per turn twice daily; most effective before the pubertal peak and confirmed by occlusal radiograph or CBCT.

Serial extraction

A planned sequence of extracting primary canines, then primary first molars, then first premolars in selected severe Class I crowding cases to guide eruption and reduce later crowding.

Le Fort I osteotomy

A maxillary osteotomy that moves the maxilla in three dimensions; used in orthognathic surgery to correct skeletal Class II, Class III, open bite, and transverse discrepancies.

BSSO

Bilateral sagittal split osteotomy, a mandibular ramus osteotomy that allows advancement, setback, and rotation of the mandible; commonly combined with Le Fort I surgery.

Forced eruption

Application of light extrusive force to move a tooth and its attachment apparatus coronally; used to improve the crown-root ratio and to place restorative margins supragingivally.

Miniscrew anchorage

A temporary anchorage device placed in alveolar or palatal bone to provide absolute anchorage for retraction, intrusion, or distalization; success depends on bone quality, torque, and root proximity.

Circumferential supracrestal fiberotomy

A procedure that severs the supracrestal periodontal fibers around a rotated tooth to reduce rotational relapse; it carries a risk of periodontal damage and is used selectively.

GRADE system

A framework for rating the certainty of evidence as high, moderate, low, or very low based on risk of bias, inconsistency, indirectness, imprecision, and publication bias.

Intention-to-treat analysis

An analysis that includes all randomized participants in the groups to which they were assigned, regardless of compliance, preserving the benefits of randomization and reducing bias.