Iran Dental Specialty Board - Orthodontics flashcards

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

Scammon's growth curve

Describes four tissue growth patterns: neural (fast early), lymphoid (fast then involution), general body (S-shaped), and genital (late growth).

Cervical vertebral maturation

CVM stages CS1-CS6 on lateral cephalogram estimate skeletal maturity; CS3-CS4 indicates peak pubertal mandibular growth.

Spheno-occipital synchondrosis

Cartilaginous growth center of the cranial base that closes around ages 12-15 in females and 14-17 in males.

ANB angle

Difference between SNA and SNB; normal about 2 degrees. Values above 4 suggest Class II skeletal pattern; negative values suggest Class III.

Wits appraisal

Projects A point and B point onto the occlusal plane; normal about 0 mm; used to assess skeletal discrepancy independent of cranial base.

FMA

Frankfort-mandibular plane angle; normal about 25 degrees; high values indicate hyperdivergent pattern.

Center of resistance

Point in a tooth where a force produces pure translation; located roughly at one-third to one-half root length from alveolar crest for single-rooted teeth.

Moment-to-force ratio

Ratio determining movement type: low for tipping, higher for translation, highest for torque; threshold depends on tooth morphology and root length.

Pressure-tension theory

Orthodontic force creates compression and tension in the periodontal ligament, leading to resorption on the compression side and deposition on the tension side.

Hyalinization

Avascular necrosis of the periodontal ligament on the compression side under heavy force; delays tooth movement and increases root resorption risk.

Superelasticity

Property of nickel-titanium wires where stress-induced martensite allows large deflections with nearly constant force; useful for leveling and alignment.

Beta-titanium wire

Titanium-molybdenum alloy wire with stiffness between NiTi and stainless steel; weldable and used for finishing and torque.

Self-ligating brackets

Brackets with a built-in clip instead of ligatures; evidence does not consistently show faster treatment or fewer visits than conventional brackets.

Rapid maxillary expansion

Heavy-force expansion that opens the midpalatal suture; most effective before sutural fusion, typically before mid-teens.

Twin Block appliance

Two-piece functional appliance that advances the mandible and allows lateral excursions; compliance-dependent and used during growth.

Serial extraction

Planned removal of primary canines and first premolars in selected crowding cases to guide eruption; requires careful case selection and monitoring.

Space maintainer

Appliance that preserves arch space after premature loss of a primary tooth; types include band-and-loop, crown-and-loop, and removable.

Le Fort I osteotomy

Maxillary surgery that allows advancement, impaction, or setback; can correct vertical and transverse discrepancies.

BSSO

Bilateral sagittal split osteotomy of the mandible for advancement or setback; risk of inferior alveolar nerve injury.

Distraction osteogenesis

Gradual bone lengthening by controlled separation of osteotomy segments; phases include latency, distraction (~1 mm/day), and consolidation.

Hawley retainer

Removable acrylic appliance with wire clasps; durable and allows some occlusal settling; used for retention after orthodontic treatment.

Essix retainer

Clear thermoplastic overlay retainer; esthetic but less durable; long-term full-time wear can cause bite changes.

Fixed lingual retainer

Wire bonded to the lingual surfaces of anterior teeth; effective for lower incisor retention; risk of bond failure and calculus accumulation.

Forced eruption

Orthodontic extrusion of a tooth to improve gingival margin and bone level; used for crown-root fractures and periodontal defects.

White spot lesions

Enamel decalcification caused by plaque accumulation around brackets; prevented by oral hygiene and fluoride; common orthodontic complication.

Stabilization splint

Flat-plane occlusal appliance used for TMD; evidence for efficacy is modest; avoid irreversible occlusal adjustment as first-line therapy.

Mutually protected occlusion

Occlusal scheme where anterior teeth protect posterior teeth in excursion and posterior teeth protect anterior teeth in centric occlusion.

PICO framework

Population, Intervention, Comparison, Outcome; structured approach to formulating a clinical question and search strategy.

Intention-to-treat analysis

Analysis that includes all randomized participants in their assigned groups; preserves randomization and reduces bias from dropout.

Bolton analysis

Compares mesiodistal tooth widths; anterior ratio about 77.2% and overall about 91.3%; discrepancy indicates tooth size imbalance.

Tanaka-Johnston analysis

Mixed dentition space analysis that estimates widths of unerupted canines and premolars from lower incisor widths.

Cranial base superimposition

Cephalometric method using S-N or other cranial base structures to assess overall skeletal change over time.