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Quick Reference Index

Orthodontic Appliances

Corrective Orthodontics

Surgical Orthodontics, Retention & Relapse

Miscellaneous

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ORTHODONTIC APPLIANCES

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1. Define Orthodontic Appliance + Principles of Appliance Designing

• Force should be within physiologic limits (light, continuous forces preferred)
• Optimal forces: Tipping - 35-60 g; Bodily movement - 70-120 g; Intrusion - 10-20 g; Extrusion - 35-60 g; Rotation - 35-60 g
• Hyalinization and root resorption must be minimized
• Allow for periods of recovery between activations

• Line of force should pass through (or near) the center of resistance of the tooth
• Moment/force ratio determines type of tooth movement
• Minimize friction (especially in sliding mechanics)
• Use appropriate wire size and material for each stage

• Appliance should not harm periodontium, mucosa, or tooth structure
• Must be comfortable and allow adequate speech
• Easy to insert, remove, and adjust
• Hygienic maintenance must be feasible

• Retentive elements provide anchorage and hold the appliance
• Active elements produce the desired tooth movement
• Baseplate/archwire provides structural integrity
• Force system must be predictable, controllable, and appropriate for the tooth to be moved

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2. Functional Appliances - Definition, Indications, Components, Timing, Working Theory

• Skeletal Class II with retrognathic mandible (primary indication)
• Skeletal Class III (FR-III, reverse activator)
• Correction of functional mandibular shifts
• Habit breaking
• Vertical growth problems (depending on design)
• Best used during active growth - mixed or early permanent dentition

• Large acrylic body (upper and lower joined)
• Labial bow (0.9 mm SS wire - passive)
• Posterior acrylic contacts on upper molars (holding upper arch)
• Lower incisor capping or contact
• Construction bite in forward-postured position

• Peak pubertal growth spurt is ideal
• CVM (Cervical Vertebral Maturation): Stage CS3/CS4
• Hand-wrist radiograph: MP3-F to MP3-G stage
• Girls: approximately 10-12 years; Boys: approximately 12-14 years
• Can also be used in late mixed dentition (8-10 years) for pre-functional treatment

1. Mandible postured forward (3-5 mm sagittal, 4-6 mm vertical opening)
2. Orofacial muscles stretched (especially inferior head of lateral pterygoid)
3. Stretched muscles transmit forces via condyle to glenoid fossa
4. Stimulates condylar cartilage cell division and new bone at posterior condyle
5. Glenoid fossa remodels anteriorly
6. Net result: Mandibular lengthening and forward repositioning
7. Dentoalveolar effects: Upper incisors retracted, lower incisors proclined, Class II molar relationship corrected

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3. Myofunctional Appliances - Classification + Activator

• Tissue-borne: Activator, Bionator, Frankel (FR)
• Tooth-borne: Twin Block, Herbst, Jasper Jumper, MARA

• Removable: Activator, Bionator, Twin Block (removable), FR
• Fixed: Herbst, Jasper Jumper, Forsus spring, MARA

• Passive (tissue screen type): FR, oral screen
• Active (muscle stretch type): Activator, Herbst

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• Class II div 1 malocclusion with retrognathic mandible
• Growing patient (8-14 years)
• Deepbite with Class II
• Anterior open bite (modified construction bite with less opening)
• Class II div 2 (with labial bow modification)
• Habit breaking (digit sucking)

1. Construction bite: 3-5 mm anterior posture; 4-6 mm vertical opening (2-3 mm beyond freeway space)
2. Muscle stretch: Lateral pterygoid, masseter, medial pterygoid are stretched - transmit forward force to condyle
3. Condylar effects: Enhanced condylar cartilage growth; posterior condylar bone apposition; glenoid fossa anterior displacement
4. Upper dental effects: Upper incisors retracted by labial bow pressure; upper molars distalized by acrylic contact
5. Lower dental effects: Lower incisors may procline (if acrylic contacts lower incisors)
6. Net result: Class II correction via both skeletal (mandibular advancement) and dental mechanisms

• Bulky - poor compliance (worn only at night)
• Requires significant growth remaining
• Primarily tipping effect on incisors

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4. Oral Screen (Vestibular Screen)

• An acrylic shield placed in the vestibule between the lips/cheeks and the labial/buccal surfaces of teeth
• Introduced by: Newell; popularized by Kraus
• Wire reinforcement: 1.0 mm SS frame embedded in acrylic for rigidity

1. Simple oral screen (solid)
2. Oral screen with breathing holes (for mouth breathers - transition to nasal breathing)
3. Activator-type oral screen (Kraus) - with posterior acrylic extension

• Eliminates abnormal lip and cheek muscle pressures
• Habit breaking: thumb sucking, lip sucking, finger sucking
• Promotes nasal breathing
• Corrects lip incompetence
• Simple proclination of upper incisors due to lip pressure corrected
• Lip seal training

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5. Canine Retractors

1. Palatal finger spring (simple cantilever): 0.5 mm SS; coil at gingival margin; moves canine distally by tipping; activation 2-3 mm
2. Helical canine retractor: Palatal or buccal; helix incorporated to reduce force and increase range; 0.5 mm SS
3. Robert's retractor: Two helices; more flexible; self-limiting; 0.5 mm SS; most commonly used; guide arm embedded in baseplate; active arm contacts mesial of canine
4. Buccal canine retractor: Spring on buccal aspect; less lever arm but can be combined with palatal spring for rotation control

1. Retraction loop archwires:
   • Vertical loop (bull loop): 2 mm activation
   • L-loop, T-loop: more flexible, lighter force
   • Helical loops
2. Closed coil NiTi spring: Between canine bracket and molar tube
3. Elastic power chain: Continuous elastomeric O-rings
4. Frictionless mechanics: TMA T-loop for canine retraction

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6. Expansion Screws

• Mechanical devices placed within the baseplate of removable appliances or fixed expanders to produce arch widening
• One quarter turn = 0.25 mm expansion
• One full turn = 1.0 mm expansion

1. Simple midline screw: For symmetric bilateral expansion
2. Fan-type screw: Positioned anteriorly; expands anterior arch more than posterior (for V-shaped arch)
3. Y-shaped screw (three-way): Three-directional expansion
4. Minne expander
5. Hyrax (Haas-type): Fixed palatal expander with central screw bonded to molar bands

• Slow expansion (tooth-borne): 1 turn every 3-7 days (0.25-0.5 mm/week)
• Rapid Palatal Expansion (RPE): 2 turns/day (0.5 mm/day); opens midpalatal suture

• Narrow maxillary arch
• Posterior unilateral or bilateral crossbite
• Arch length deficiency
• Correction of functional shift

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7. Activator

• Introduced by Viggo Andresen and Karl Haupl (1936)
• Also called "Norwegian appliance" or "monobloc" type
• Construction bite: 3-5 mm forward; 4-6 mm vertical
• Acrylic capping of lower incisors (retaining lower incisors) - varies by design
• Night-time wear (10-14 hours)
• Typical treatment duration: 12-18 months of active wear
• Best combined with fixed appliances in Phase II for detailing

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8. Components of Removable Appliances

• Springs: Finger spring (0.5 mm), Z-spring, T-spring, palatal canine retractor, double cantilever spring
• Labial bows: 0.7 mm; can be active (cinching) or passive
• Screws: Expansion screws (0.25 mm per quarter turn)
• Elastics: Attached to hooks on clasps

• Adams clasp: Most important; 0.7 mm (premolars) or 0.8 mm (molars); engages mesiobuccal and distobuccal undercuts
• Ball-ended clasp: 0.7 mm; engages embrasure spaces
• Southend clasp: Modified Adams for anterior teeth; engages central incisors
• Arrowhead clasp

• Baseplate provides indirect anchorage
• Posterior bite planes
• Bite platforms

• Self-cured or heat-cured acrylic (polymethylmethacrylate)
• 2-3 mm thick
• Supports and connects all components
• Can be modified with bite planes, slopes, acrylic capping

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9. Lip Bumper

• A removable extraoral appliance consisting of an acrylic or wire pad held at a distance from the labial surfaces of lower incisors and premolars by a heavy stainless steel wire (1.0-1.2 mm) inserted into buccal tubes on lower molar bands

1. Lower lip bumper (most common)
2. Upper lip bumper (rare)

• Holds lips away from teeth, eliminating lip pressure on lower anteriors
• The pressure from lips is redirected to the molars (through the buccal tubes)
• Creates a net distal/outward force on the molars while relieving pressure on incisors

1. Preservation of leeway space (mixed dentition)
2. Lower arch expansion (mild crowding - non-extraction alternative)
3. Molar distalization (using lip pressure as the force)
4. Lower incisor proclination (if lip pressure was causing retroclination)
5. Anchorage reinforcement for lower molars

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10. Begg vs Straight Wire Appliance

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11. Twin Block Appliance

• Two separate upper and lower removable acrylic appliances
• Worn simultaneously; interdigitate on occlusion

• Midline expansion screw
• Adams clasps on upper 6s and 4s (or 5s)
• Anterior labial bow (0.7 mm SS)
• Posterior bite blocks with 70° occlusal inclined planes (on upper posterior teeth - mesial slope)
• Palatal coverage

• Adams clasps on lower 6s
• Labial bow
• Posterior bite blocks with complementary inclined planes (distal slope on lower premolar/molar region)
• Lower incisor capping (optional)

• When patient closes, the upper and lower inclined planes (70° to occlusal plane) engage
• This forces the mandible to posture anteriorly
• Bilateral occlusal contact transmits forces to bone via teeth
• Condyle displaced anteriorly and inferiorly → stimulates condylar growth and glenoid fossa remodeling

• 5-7 mm anterior posture (beyond Class I)
• 2-4 mm vertical opening

• Growing patients (8-14 years) with Class II div 1 malocclusion
• Retrognathic mandible

• Full-time wear including eating (better compliance)
• Separate upper and lower (more comfortable)
• Rapid correction (6-9 months)
• Allows normal function during treatment

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12. Classification of Springs

• Cantilever (single free end): Finger spring, buccal/palatal canine retractor
• Double cantilever (both ends free with a common base): Z-spring, T-spring, coffin spring

• Palatal springs: Finger spring, Robert's retractor, coffin spring
• Buccal springs: Buccal canine retractor
• Labial springs: Active labial bow, Z-spring

• 0.5 mm: Finger spring, Z-spring, canine retractors
• 0.6 mm: Double cantilever auxiliary springs
• 0.7 mm: Labial bow, Adams clasp
• 0.9 mm: Heavy springs, headgear inner bow component
• 1.25 mm: Coffin spring (major connector)

• Active springs: Produce tooth movement
• Passive springs: Retentive (help hold appliance)

• With helix/coil: Helical canine retractor, Robert's retractor (increased range, lighter force)
• Without helix: Simple finger spring

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13. Nitinol Archwires

1. Conventional/Martensitic NiTi (Unitek Nitinol): Work-hardened; no true superelasticity; cannot be bent; useful but not thermoelastic
2. Superelastic/Austenitic active NiTi: True flat plateau on load-deflection curve; constant force over large deflection range; GAC, Rocky Mountain NiTi
3. Thermally activated NiTi (TANT): Phase transformation near body temperature; Copper NiTi (27°C, 35°C, 40°C grades); Neo-Sentalloy; flexible at room temp, delivers force at mouth temp
4. Chinese NiTi (Yanghang): Martensitic; highly flexible; inconsistent

• Initial alignment archwires (0.014, 0.016 NiTi) - heavy crowding
• Light continuous forces ideal for initial leveling and alignment
• Cannot be bent, soldered, or welded (limitation)
• MRI safe (no ferromagnetic properties)

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14. Bonding in Orthodontics

• 37% orthophosphoric acid applied 15-30 seconds
• Creates microporous enamel surface (removes prism peripheries)
• Three etch patterns: Type 1 (prism cores dissolved), Type 2 (prism peripheries dissolved), Type 3 (irregular)
• Increases surface area 2000-fold
• Bond strength achieved: 20-30 MPa (clinically adequate: 6-8 MPa)

1. Pumice prophylaxis (remove plaque and pellicle)
2. Isolation (cotton rolls, lip retractor, suction)
3. Acid etching (37% H₃PO₄; 15-30 sec; rinse 15 sec; dry = chalky white appearance)
4. Primer application (unfilled resin; air-thin)
5. Apply adhesive to bracket base
6. Seat bracket at correct position and height
7. Remove flash
8. Light cure 20-40 seconds (or chemical cure 3-4 minutes)

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15. Adams Clasp and Modifications

• Most widely used retentive component of removable appliances
• Designed by C.P. Adams (1948) as a modification of the arrow-head clasp

• 0.7 mm SS for premolars
• 0.8 mm SS for permanent molars
• 0.6 mm SS for deciduous molars

1. Two arrowheads (tags): Engage mesiobuccal and distobuccal undercuts of the tooth
2. Two bridges (flyover): Cross the buccal surface above the height of contour; provide structural support
3. Cross-arch section: Lies along buccal surface; embedded in baseplate at both ends

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16. Components of Fixed Appliances

• Thin (0.15-0.18 mm) stainless steel rings cemented to posterior teeth
• Provide attachment for molar tubes, headgear tubes, lingual arch tubes
• Cemented with glass ionomer cement (fluoride releasing)

• Bonded to anterior teeth and premolars
• Types: Standard edgewise, preadjusted (SWA), self-ligating (Damon, Speed), lingual
• Parts: Base (mesh for bonding), slot (engages archwire), wings (ligature tie-back)
• Materials: SS (most common), ceramic (aesthetic), plastic, titanium

• Attached to molar bands
• Round tube (0.045"): For headgear inner bow
• Rectangular tube (0.022"): For main archwire
• Convertible tubes (can be opened to bracket)

• NiTi: Initial alignment
• Stainless steel: Leveling, space closure, finishing
• TMA (Beta-titanium): Loop mechanics, finishing
• Elgiloy: Loop mechanics, springs
• Cross-sections: Round, square, rectangular

• Elastic ligatures and steel ligature wires
• Intermaxillary elastics (Class I, II, III)
• Open and closed coil springs
• Power chains / elastic chains
• Torquing auxiliaries
• Uprighting springs

• Lingual arch, transpalatal arch (TPA): Anchorage control
• Nance appliance: Anterior palatal pad for anchorage
• TADs/mini-screws: Absolute anchorage
• Hooks and cleats for elastic attachment

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17. Ideal Requisites of a Removable Orthodontic Appliance

1. Adequate retention - should not dislodge during speech or eating
2. Simple design - minimal components for reliability and patient compliance
3. Hygienic - easily cleaned with toothbrush and water; no food trap design
4. Comfortable - smooth surfaces; no sharp edges; minimal bulk
5. Minimal speech interference - avoid thick anterior coverage if possible
6. Structural rigidity - baseplate should not flex or fracture during use
7. Controlled force delivery - active components deliver biologically appropriate (light, continuous) forces
8. Non-restrictive - should not impede normal jaw growth or eruption of teeth not being treated
9. Durable and repairable - components can be added/repaired chairside
10. Tissue compatible - acrylic and wire should be biocompatible; no allergens
11. Economical - cost-effective for patient and simple to fabricate in the lab
12. Adjustable - can be modified to change force direction/magnitude as treatment progresses

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18. Fixed Orthodontic Appliances and Components

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19. Functional Regulator (Frankel Appliance)

• FR-I: Class II div 1
• FR-II: Class II div 2
• FR-III: Class III (maxillary deficiency)
• FR-IV: Open bite and bimaxillary protrusion

• Buccal shields: Large acrylic pads on buccal sides; positioned 2-3 mm away from buccal alveolus; eliminate buccal muscle pressure; allow buccal expansion
• Lip pads (lower): Positioned away from lower labial alveolus; eliminate mentalis and lower lip pressure on mandibular dentoalveolus; allow lower arch forward development

• Palatal bow (1.2 mm SS): Crosses palate; provides upper arch contact/stability
• Canine loops (0.9 mm): Engage canine embrasures anteriorly and posteriorly
• Upper labial bow (0.9 mm): Controls upper lip; may retract upper incisors
• Protrusion bow / lower labial bow (0.9 mm): Prevents lower incisor proclination

• Vestibular shields and lip pads eliminate restrictive perioral forces
• Creates new neuromuscular environment
• Transmucosal forces from shields stretch periosteum → stimulates bone apposition in alveolus
• No direct mechanical force on crowns
• Results in arch development through removal of pathologic muscle restraint

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20. Double Cantilever Spring

• Two helices; total wire 0.5 mm SS
• Shape resembles letter Z
• Arms enter baseplate at an angle
• Active tip deflects labially
• Use: Labial proclination of individual incisors trapped in crossbite; mesiobuccal movement
• Activation: 3 mm forward deflection
• Force: ~30-40 g

• T-shaped design; single coil; 0.5 mm SS
• Active arm contacts lingual of incisor
• Use: Labial movement of individual incisor
• Activation: 2-3 mm

• Large omega-shaped spring in midpalate; 1.25 mm SS
• Bilateral expansion; used as midline spring
• Also used as connector between two halves of split plate
• Force: ~200-300 g

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21. Welding and Soldering in Orthodontics

• Hard soldering (Brazing): Solder melts >450°C; silver solder used; for stainless steel orthodontic joints; strong bond
• Soft soldering: Solder melts <450°C; tin-lead alloys; not suitable for orthodontic SS (too weak and corrodes)

• Solder: Silver-containing alloy (Easy-Flo: Ag 50%, Cu 16%, Zn 15%, Cd 19%)
• Flux: Prevents oxidation; allows wetting; borax or fluoride-containing pastes
• Anti-flux: Prevents solder flow to unwanted areas (rouge, nail polish, graphite)
• Heat source: Soldering torch, Bunsen burner

1. Fit parts together precisely
2. Apply flux to joint area; apply anti-flux elsewhere
3. Heat to soldering temperature (straw-yellow color for SS)
4. Apply solder to joint (flows by capillary action)
5. Quench in water; clean flux residue

• Resistance spot welding (electric) is the only practical welding used
• Two copper electrodes clamp the parts together; brief electric current passes; resistance generates heat; metals fuse at contact point
• Uses: Attaching brackets, cleats, hooks to bands; joining band material

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22. Reverse Pull Headgear (Protraction Headgear / Facemask)

• An extraoral appliance that applies forward and downward traction to the maxilla
• Used to treat Class III malocclusion due to maxillary retrusion/deficiency in growing patients

1. Forehead pad: Rests on forehead; part of extraoral support frame
2. Chin pad: Rests on chin; part of extraoral support frame
3. Rigid frame: Connects forehead and chin pads; forms the extraoral support structure
4. Crossbow (horizontal bar): Projection from frame at lip level; has hooks for elastic attachment
5. Elastics: Connect from intraoral hooks to crossbow hooks; provide protraction force
6. Intraoral anchor: Palatal expander with anterior hooks, or bonded upper arch device

• Traction through maxillary teeth → transmitted through alveolus → opens all circummaxillary sutures
• New bone deposited at posterior suture margins
• Net forward displacement of maxilla
• Often combined with rapid palatal expansion (RPE) to loosen sutures and enhance protraction response

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23. Cantilever Springs

• Force = (3EI × δ) / L³
• Doubling the length reduces force by 8 times (force ∝ 1/L³)
• Adding a coil/helix increases effective length without increasing physical length

• Wire: 0.5 mm SS
• Parts: Coil (3 mm diameter, 2-3 turns), active arm, guide arm
• Coil position: At gingival margin level
• Guide arm: Embedded in baseplate alongside active arm for support
• Activation: 2-3 mm
• Force: 30-50 g
• Uses: Mesial/distal movement of teeth; labial movement of incisors

• Same construction; placed on palatal side
• Used for distal movement of premolars before extraction space opens

• Placed buccally; less frequently used

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24. Advantages and Disadvantages of Removable Appliances [2M]

1. Simple construction and repair in the laboratory
2. Patient can remove for meals, sports, and oral hygiene
3. Allows normal oral hygiene - lower risk of decalcification
4. Useful for simple tipping movements
5. Can be combined with other appliances
6. Can incorporate bite planes, screw expansion, and springs simultaneously
7. Lower cost than fixed appliances
8. Less risk of root resorption
9. Can be used as retainers after fixed treatment

1. Entirely dependent on patient compliance
2. Only produces tipping movements (cannot reliably bodily move, torque, or rotate teeth)
3. Limited to simpler cases
4. Speech interference (lisping)
5. Risk of loss or swallowing (especially in children)
6. Less precise control of individual tooth movements
7. Ineffective in uncooperative patients
8. Cannot be used for complex three-dimensional movements

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25. Different Fixed Appliance Systems

1. Angle edgewise (1928) - rectangular slot; foundation of modern fixed appliances
2. Begg light wire differential force (1956) - pin-and-tube; tipping then uprighting
3. Tip-Edge / Tip-Edge Plus (Kesling, 1988) - modified slot; combines Begg tipping with edgewise finishing
4. Straight Wire Appliance / SWA (Andrews, 1970) - preadjusted brackets
5. Roth prescription SWA - modified prescriptions for routine extraction and non-extraction
6. MBT prescription (McLaughlin-Bennett-Trevisi, 1997) - low torque values; torque expressed via rectangular wire
7. Alexander discipline
8. Damon self-ligating (passive) - passive clip; low friction; Damon Q, Damon 3MX
9. SPEED appliance (Hanson, 1980) - active self-ligating spring clip
10. In-Ovation (active self-ligating)
11. Lingual systems: Incognito (CAD/CAM custom), STb, 2D appliance
12. Rocky Mountain bracket system
13. MEAW (Multiloop Edgewise Archwire) - Kim's appliance for open bite

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26. Active Components of Fixed Appliance

1. Archwires:
   • NiTi (initial alignment): 0.012, 0.014, 0.016, 0.018 round; then 0.016×0.022 rectangular NiTi
   • SS (space closure, finishing): 0.019×0.025 SS
   • TMA/Beta-Ti: Loop mechanics, closing loops
   • Utility arch (Ricketts): Intrusion of incisors
2. Intermaxillary elastics:
   • Class I: Within arch
   • Class II: Upper molar to lower canine hook
   • Class III: Lower molar to upper canine hook
   • Vertical: Close open bite
   • Cross-arch: Correct buccal crossbite
   • Box elastics: Extrude teeth to close open bite
3. Coil springs:
   • Open coil NiTi: Space creation (pushes teeth apart)
   • Closed coil SS: Space closure (pulls teeth together)
4. Power/Elastic chain: O-ring elastic modules linked together; space closure
5. Torquing auxiliaries: For root torque in Begg technique
6. Rotation wedges/elastic separators: Correct rotations
7. TADs (Temporary Anchorage Devices): Provide absolute anchorage for:
   • En-masse retraction
   • Intrusion of incisors or molars
   • Molar distalization
8. Fixed functional appliances: Herbst, Jasper Jumper, Forsus (active components for Class II correction)

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27. Catalans Appliance (Tooth Positioner)

• A removable appliance made from a soft elastomeric material (silicone rubber or thermoplastic) or hard acrylic
• Covers all teeth of both arches simultaneously
• The teeth fit into precisely carved recesses in a slightly corrected/ideal position

1. Finishing: Minor tooth movements (1-2 mm) after fixed appliance removal
2. Retention: Holds corrected position during early retention phase
3. Postured mandibular position maintenance (functional-type positioner)
4. Detailing contacts and occlusal relationships

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28. Pterygoid Response

• The neuromuscular response triggered when a functional appliance posturs the mandible in a forward position

1. Functional appliance (activator, Twin Block, etc.) forces mandibular posture forward
2. Inferior head of lateral pterygoid is stretched and activated
3. This muscle attaches to the condylar neck and articular disc
4. Repeated muscle activation → increased cell division in condylar cartilage (Petrovic's research)
5. Enhanced endochondral ossification at posterior surface of condyle
6. Glenoid fossa remodels anteriorly to accommodate repositioned condyle
7. Net result: True increase in mandibular length + anterior positioning

• Petrovic (1975): Lateral pterygoid stimulation increases condylar growth rate
• McNamara (1973): Increased condylar growth rate with postured mandible
• Controversy: Some authors argue effects are primarily dentoalveolar

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29. Visual Treatment Objective (VTO)

• Treatment planning tool
• Communication with patient/parents (shows expected change)
• Compare actual treatment result with planned outcome
• Research and audit

1. Growth VTO: Shows expected position with growth only (no treatment)
2. Treatment VTO: Shows expected position with growth + treatment intervention
3. Computer-generated VTO (Ricketts Dolphin, WinCeph programs)

1. Trace current lateral cephalogram
2. Superimpose expected growth template for patient's age/gender (e.g., 1 mm/year maxillary growth; 2-3 mm/year mandibular growth)
3. Add anticipated dental changes (retraction of incisors, molar movements based on extractions)
4. Draw expected soft tissue changes (lip position follows incisor movement - Holdaway's line)
5. Final tracing = VTO

• Skeletal (A, B points, pogonion, menton)
• Dental (incisor position, molar position)
• Soft tissue (lip position, profile)

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30. Modifications of Activator

1. Herren activator (active-type): Maximum posture; incisors are capped; more aggressive approach for severe Class II
2. Woodside activator: Different geometric configuration; modified construction bite
3. Harvold activator (Norwegian type): Very large vertical opening (8-12 mm); produces strong muscle stretch; designed for vertical control
4. Hamilton activator
5. Bionator (Balters, 1964):
   • Open design (much less acrylic than activator)
   • Buccal acrylic shields (like FR)
   • Central palatal wire loop
   • Tongue crib/bow to train tongue
   • Types: Class II (standard), Class III (reverse bionator), Open bite bionator
6. Kinetor (Stockfish)
7. Teuscher activator-headgear combination: Hooks for high-pull headgear incorporated; for vertical control in high-angle Class II cases
8. Magnetic activator device (MAD): Rare earth magnets embedded; attractive or repulsive forces
9. Elastic open activator (Van Beek)
10. Acrylic splint activator (modified Andresen)
11. L.S.U. activator

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31. Helical Canine Retractor

• A palatal or buccal spring for retracting upper canines in a removable appliance, with a helix (coil) incorporated in the spring body

• Wire: 0.5 mm SS
• A circular coil (helix) is formed near the baseplate attachment
• The active arm extends from the helix and terminates at the mesial aspect of the canine (palatal variety)
• Guide arm embedded in baseplate

• Increases effective wire length (without increasing physical dimension)
• Reduces force/deflection ratio = lighter, more continuous force
• Increases range of action before reactivation is needed

1. Palatal helical canine retractor: Most common; coil on palatal side; moves canine lingually and distally
2. Buccal helical retractor: Coil on buccal side; less commonly used

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32. Finger Spring

• The simplest and most commonly used active spring in removable appliances
• A single cantilever spring

• Wire: 0.5 mm SS (most common)
• Coil: 2-3 turns; diameter 3 mm; positioned at gingival margin level; increases range and reduces force
• Active arm: Extends from coil to contact tooth surface
• Guide arm: Parallel to active arm; embedded in baseplate alongside active arm; provides directional guidance and prevents spring distortion

• Distal movement of upper premolars/molars
• Mesial movement of teeth
• Labial movement of individual incisors in crossbite
• As component in canine retractors

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33. Chin Cap

• An extraoral appliance that applies force to the chin (symphysis of mandible) in a posterior or superior direction
• Used to modify mandibular growth in Class III patients

1. Occipital pull chin cap:
   • Strap attaches to occipital region of head
   • Force directed backward-upward (toward sella/occipital)
   • Retards mandibular growth; redirects growth in a clockwise direction
   • Most commonly used for Class III in growing children
2. Vertical chin cap:
   • Force directed straight upward
   • Reduces lower anterior facial height
   • Used for anterior open bite with mandibular excess

• Restricts forward mandibular growth (orthopedic)
• Clockwise rotation of mandible (reduces Class III)
• Tipping of lower incisors lingually
• TMJ remodeling (concern with heavy forces - condylar flattening reported)

• Primarily dentoalveolar effect if used after growth spurt
• High relapse rate without long-term retention
• TMJ concerns with heavy, prolonged forces
• Cannot correct skeletal Class III in adults

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34. Petit Facemask

• The most widely used design of reverse-pull (protraction) headgear
• Designed by Jean Petit (1983)

• Forehead rest pad: Padded contact on forehead
• Chin rest pad: Padded contact on chin
• Vertical metal frame: Rigid; connects forehead and chin pads bilaterally
• Horizontal crossbow: Projecting anteriorly at lip level; bilateral hooks for elastic attachment
• Intraoral anchor: Palatal expander with anterior hooks (most common) or bonded hook appliance

• Elastics run from intraoral hooks (on palatal expander) to hooks on crossbow
• Force direction: Forward and 30° downward from occlusal plane
• Force: 300-600 g per side
• Creates traction on maxilla through all circummaxillary sutures

• Class III malocclusion with maxillary retrusion/deficiency
• Ages 5-10 years ideal (sutural response greatest)
• Combined with rapid palatal expansion (RPE) to enhance suture response
• Worn 12-16 hours/day

• Forward maxillary displacement (1-2 mm)
• Slight clockwise rotation of maxilla
• Dental proclination of upper incisors
• Dental retroclination of lower incisors
• Mandible may autorotate slightly posteriorly

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35. Headgear

• An extraoral appliance that uses the head or neck as a fixed anchorage base to apply orthopedic forces to the maxillary teeth and jaw

• Facebow (inner and outer bows): Inner bow inserts into molar buccal tubes; outer bow provides attachment for traction device
• Cervical strap (neck pad): For cervical pull
• Head cap (occipital strap): For high pull
• Safety locks and modules: Prevent injury from dislodgement during sleep

1. Restrains maxillary forward growth (primary orthopedic effect)
2. Distalizes upper molars (dental effect)
3. Reinforces posterior anchorage
4. Extrudes/intrudes molars depending on outer bow height
5. Redirects eruption path of upper molars

• High outer bow (above occlusal plane): High-pull forces; intrudes molars
• Low outer bow (below occlusal plane): Cervical forces; extrudes molars

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36. Purpose of Incorporating Helix in Spring Design

1. Increases effective wire length without increasing the physical/dimensional size of the spring
   • By coiling the wire into circular helix, many millimeters of wire are packed into a small space
2. Reduces force/deflection ratio (stiffness)
   • Force is inversely proportional to L³
   • More wire length = much lower force per mm of deflection
   • Produces lighter, more biologically appropriate forces
3. Increases range of activation
   • Spring can be deflected further before requiring reactivation
   • Clinical consequence: Fewer adjustment appointments needed
4. Improves flexibility
   • Spring is more resilient and less likely to lose its shape with repeated activation
5. Prevents force peaks
   • Without a helix, spring force drops off rapidly after activation
   • With a helix, force delivery is more constant over the full range

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37. Jasper Jumper

• A fixed functional Class II corrector that requires no patient compliance
• Invented by Jack Jasper (1987)

• A flexible coil spring module made of stainless steel coil encased in plastic/polycarbonate sheath
• Ends: Ball and socket attachment
• Upper attachment: Ball end inserts into a special auxiliary tube on the upper molar band (above the main archwire tube)
• Lower attachment: Pin/hook attaches to the lower archwire between the lower canine and first premolar area

• Module spans from upper molar to lower arch
• Keeps mandible in a forward-postured position continuously (24 hours)
• Creates a Class II-correcting force (upper posterior = distal force; lower anterior = mesial/forward force)
• Force: approximately 150-200 g per side

• Class II malocclusion in growing patients who have poor compliance with removable functional appliances
• Used simultaneously with fixed appliances

• No patient compliance needed
• Works 24 hours/day
• Can be used alongside comprehensive fixed appliance treatment

• Lower incisor proclination (most common side effect)
• Discomfort initially
• Module breakage
• Cannot easily control vertical dimension
• Expensive

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38. Buccal Canine Retractor

• A spring placed on the buccal aspect of the dental arch used to retract/tip the upper canine
• Wire: 0.5 mm SS
• The spring is embedded in the baseplate at the molar region and extends anteriorly on the buccal surface
• The active tip contacts the buccal surface or the distal aspect of the canine
• Less commonly used than palatal retractors because:
  • Shorter lever arm (less mechanical advantage)
  • Less comfortable
  • Can be distorted by cheek pressure

• When palatal approach is impractical (e.g., palatal torus)
• Combined with palatal spring for rotation control of the canine
• To retract a buccally displaced canine that is not accessible from the palate

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39. Robert's Retractor

• A palatal canine retractor with two helices providing greater range and lower force than a simple helical retractor
• Wire: 0.5 mm SS

• First helix (posterior/proximal): Adjacent to baseplate; guide section embedded in baseplate
• Second helix (anterior/distal): Provides additional flexibility
• Active arm: Extends from second helix anteriorly and then recurves at its tip to contact the mesial surface of the canine from the distal
• Guide arm: Embedded in baseplate from first helix; provides direction control

• Dramatically increases effective wire length
• Force/deflection ratio is very low = very light, very continuous forces
• Spring is self-limiting (won't over-activate)
• Range of activation is large

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40. Use of Elastics in Orthodontics

1. Intra-arch (Class I) elastics: Teeth within the same arch; for space closure, diastema closure
2. Inter-arch Class II elastics: From upper molar hook → lower canine/archwire hook; protracts lower arch, retracts upper; correct Class II relationship
3. Inter-arch Class III elastics: From lower molar → upper canine hook; correct Class III
4. Vertical elastics: Between upper and lower hooks in same region; extrude teeth; close anterior or posterior open bite
5. Cross-arch (diagonal) elastics: Correct unilateral posterior crossbite; from upper buccal to lower lingual hooks

• Latex (most common): Standard rubber; good force/extension properties
• Non-latex (polyurethane): For patients with latex allergy; slightly lower force levels

• Diameter: 1/4", 3/16", 5/16", 3/8"
• Force: Light (2 oz/56 g), Medium (3.5 oz/100 g), Heavy (4.5 oz/127 g), Extra heavy

• Worn 22 hours/day; remove for brushing only
• Changed daily (latex loses force within 24 hours due to degradation)
• Forces should be light and continuous (avoid heavy forces causing extrusion of anchor teeth)

• Mesial movement of lower molars
• Distal tipping of upper anteriors
• Extrusion of upper anteriors and lower molars
• Clockwise rotation of occlusal plane (worsens in high-angle cases)

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CORRECTIVE ORTHODONTICS

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41. Skeletal Class III with Angle's Class III Subdivision - 9-Year-Old Boy

• Strong hereditary pattern; autosomal dominant with variable penetrance
• Examples: Habsburg jaw (historical), familial Class III
• Gene mutations (DUSP6, CACNA1B gene associations reported)

• Mandibular prognathism (excess mandibular size or forward position)
• Maxillary retrusion/deficiency (most common in Asian populations)
• Combination of both

• Thumb sucking habit (rarely causes Class III)
• Anterior crossbite habit (postures mandible forward - pseudo Class III)
• Premature loss of upper deciduous teeth causing forward drift of lower arch

• Concave (dish-face) profile
• Prognathic chin with prominent mandible
• Retruded mid-face (if maxillary deficiency)
• Obtuse nasolabial angle (>110°)
• Reverse lip relationship (lower lip anterior to upper lip)
• Protruding lower lip; flat or inverted upper lip

• Class III molar relationship (lower first molar mesial to upper)
• Subdivision = Class III on one side, Class I on the other
• Anterior crossbite (negative overjet / reverse overjet)
• Edge-to-edge incisors or reverse bite
• Crowding in upper arch; spacing in lower arch
• Narrow upper arch with posterior crossbite possible
• Prognathic-appearing lower incisors; retroclined upper incisors (compensation)

• Lateral cephalogram:
  • ANB < 0° (negative)
  • Wits appraisal < 0
  • SNB > 82°; SNA may be reduced
  • Mandibular plane angle assessment
• OPG: All teeth, root lengths, bone levels
• Study models: Arch length analysis, crossbite documentation
• Clinical photographs: Extraoral (front, profile, 45°) + Intraoral
• Hand-wrist radiograph: Growth status (MP3-F/G stage)
• PA cephalogram: Assess facial asymmetry (for subdivision)
• CBCT: If surgical correction planned

1. Maxillary protraction (Petit Facemask) + Rapid Palatal Expansion:
   • Primary treatment for maxillary retrusion
   • RPE first (2 weeks) then facemask; 300-600 g; 12-16 hrs/day
   • Best response: 5-10 years
2. Chin cap: If mandibular prognathism is primary component; redirects growth
3. FR-III (Frankel III): Lip pads on upper arch + lingual shields lower; expand upper arch; good for mild cases
4. Removal of premature contacts causing functional shift

1. Camouflage orthodontics (mild skeletal discrepancy):
   • Retract lower incisors (extract lower premolars)
   • Procline upper incisors
   • Only works if ANB not severely negative
2. Orthognathic surgery (moderate to severe skeletal discrepancy):
   • Le Fort I osteotomy (maxillary advancement)
   • Bilateral sagittal split osteotomy (BSSO) (mandibular setback)
   • Often combined (bimaxillary surgery)
   • After growth complete (18-20 years for females; 20-22 years for males)

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42. Skeletal Class II with Angle's Class II Division 1 - 9-Year-Old Boy

• Retrognathic mandible (most common in Caucasians)
• Prognathic maxilla
• Combination

• Digit sucking (thumb/finger): Proclines upper incisors, retrudes lower, creates open bite component
• Mouth breathing with adenoid hypertrophy: Adenoid facies, backward rotation of mandible
• Lip dysfunction/incompetence: Lower lip falls behind upper incisors (lip trap); further proclines upper incisors
• Nail biting, pen chewing (minor)

• Convex profile (Class II facial pattern)
• Retrognathic chin
• Incompetent lips (cannot achieve lip seal at rest without straining)
• Everted lower lip (trapped behind upper incisors)
• Deep mentolabial sulcus (deep labiomental fold)
• Short lower anterior facial height (in div 2 type) or long (mouth breathers)
• Protrusive upper lip
• Adenoid facies: Narrow nostrils, open lips, elongated face (if mouth breather)

• Class II molar relationship (upper molar mesial to lower)
• Increased overjet (>4 mm, often 6-12 mm or more)
• Deep overbite (incisors overlap excessively)
• Proclined upper incisors (labially tipped; increased angle to SN)
• Narrow maxillary arch
• High-arched palate
• Lower incisors retroclined or normal
• Posterior teeth in Class II relationship

• Lateral cephalogram:
  • ANB > 4° (increased)
  • Increased SNA or reduced SNB (or both)
  • Increased upper incisor to SN angle (>104°)
  • Wits appraisal > +2 mm
  • LAFH/TAFH ratio
• OPG + study models + photos
• Hand-wrist radiograph: CS1-CS2 at age 9 = pre-pubertal; growth remaining

1. Functional appliance: Twin Block or Activator
   • Used at CS3/CS4 (peak growth); may start CS2 for preparation
   • Posturs mandible forward; enhances condylar growth
   • Reduces overjet and corrects molar relationship
2. Headgear (cervical or high pull): Restricts maxillary growth; distalizes upper molars
3. Habit elimination: Thumb guard, reminder appliance for digit habits
4. Lip seal exercises

• After functional treatment and near completion of permanent dentition
• Comprehensive fixed appliances
• May require extractions (upper first premolars) if residual overjet/crowding
• Detail occlusion; retention

1. Camouflage: Fixed appliances + upper premolar extraction; retract upper anteriors
2. Orthognathic surgery: BSSO mandibular advancement (± Le Fort I) if severe ANB

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43. Class II Division 1 - Etiological Factors, Clinical Features, Management

• If ANB < 6° + mild crowding: Non-extraction; functional appliance then fixed
• If ANB > 6° or significant crowding or lip protrusion: Extraction of upper 1st premolars
• Lower arch: Extract lower 1st premolars only if lower crowding present

• Sliding mechanics: NiTi/SS coil spring or power chain on SS base archwire
• Loop mechanics: Closing loops (TMA or SS)

• Coordinate archwires (upper wider than lower)
• Class II elastics for residual molar correction
• Ideal overjet (2-3 mm) and overbite (2-3 mm) achieved
• Ideal Class I canine and molar relationship

• Upper: Hawley retainer or vacuum-formed retainer (VFR)
• Lower: Bonded lingual retainer + VFR

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44. Risks of Orthodontic Treatment

• Most significant biological risk
• Shortening of root apex; 1-3 mm average; >4 mm is significant
• Risk factors: Intrusive forces, long treatment duration, pipette (blunt) root morphology, previous trauma, genetic predisposition
• Monitor with periapical radiographs every 12-18 months

• Around bracket bases in poor oral hygiene
• Upper lateral incisors most commonly affected
• Prevention: Fluoride (varnish, rinse), high-fluoride toothpaste, proper patient selection, hygiene instructions

• Gingival enlargement, recession, bone loss if plaque not controlled
• Rarely caused by orthodontics alone if OH is adequate
• Risk increased with pre-existing periodontitis

• Pulp hyperemia and temporary sensitivity post-adjustment (normal)
• Pulp necrosis: Rare; more likely in previously traumatized teeth
• Obliteration of pulp canal (rare)

• Return to pre-treatment position if retention inadequate
• Highest for rotations, expanded arches, lower incisor changes

• Current evidence: Orthodontic treatment does NOT cause TMD
• Pre-existing signs/symptoms may worsen occasionally
• Functional appliances: Monitor TMJ

• Unintended movement of anchor teeth
• Results in: Upper molar mesialization, reduction of extraction space

• Expected after each adjustment; peaks 24-72 hours; resolves in 3-5 days
• NSAIDs for pain relief (but may reduce tooth movement if taken chronically)

• Nickel hypersensitivity (most common metal allergy); intraoral or dermatologic symptoms
• Management: Titanium or ceramic brackets; cobalt-chromium alternatives; latex-free elastics for latex allergy

• Risk of ingestion/aspiration; especially children
• Patient education on emergency contact

• Glass ionomer cement (fluoride releasing) reduces risk

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45. Management of Crossbite

• Z-spring or T-spring on removable appliance (with posterior bite raising to unlock)
• Posterior bite plane: Acrylic coverage posteriorly in removable appliance; unlocks the crossbite
• Fixed: Reverse stainless steel crown; composite build-up for bite jumping

• Facemask + RPE (growing patient)
• FR-III (mild cases in growing child)
• Fixed appliances + camouflage extraction (post-growth, mild)
• Orthognathic surgery (severe skeletal, post-growth)

• First eliminate functional shift
• Palatal expansion resolves true bilateral posterior crossbite
• Hyrax/bonded RPE: Most effective for bilateral crossbite

• Quad helix (fixed): Symmetric expansion with differential force
• Removable: Expansion screw + Adams clasps
• Cross-arch elastic: Buccal upper to lingual lower (or reversed) for individual tooth crossbite

• SARPE (Surgically Assisted Rapid Palatal Expansion)
• Corticotomy-assisted expansion

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46. Median Diastema and Its Treatment

1. Physiologic (developmental): Ugly duckling stage - normal in mixed dentition; self-corrects with eruption of lateral incisors and canines
2. Low/prominent labial frenum with fibrous attachment: Blanching of incisive papilla on lip traction test (positive frenum test)
3. Missing or peg-shaped lateral incisors: Removes contact that normally closes diastema
4. Mesiodens or supernumerary tooth in midline (confirmed on OPG/CBCT)
5. Midline cyst (nasopalatine cyst): OPG shows midline radiolucency
6. Habits: Digit sucking creating spacing
7. Generalized spacing (macrodontia + small arch; or microdontia)
8. Midline shift due to early premature tooth loss

• OPG: Check for mesiodens, missing laterals, bone levels, root resorption
• CBCT if OPG inconclusive for supernumerary
• Periapical X-rays
• Frenum assessment (blanching test)

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47. Anterior Open Bite

• Digit (thumb/finger) sucking: Most common in children; proclination of upper incisors + retroclination of lower incisors + anterior spacing
• Tongue thrust/tongue interposition habit
• Dummy/pacifier habit

• Hyperdivergent vertical facial pattern (increased LAFH, increased FMA)
• Increased posterior facial height (condylar-ramus excess)

• Airway obstruction/mouth breathing → backward rotation of mandible
• Condylar resorption (idiopathic, rheumatoid arthritis)
• Hemifacial microsomia
• Acromegaly (tongue enlargement)

• Teeth do not contact anteriorly despite posterior tooth contact
• Tongue or space visible between upper and lower anteriors at rest and on occlusion
• Speech defects (lisping, interdental sounds)
• Difficulty biting food
• Increased lower anterior facial height
• Hyperdivergent facial profile

• Lateral cephalogram: LAFH/TAFH ratio; FMA; Y-axis; assessment of vertical pattern
• Video recording (for tongue thrust documentation)
• CBCT (if condylar resorption suspected)

1. Habit-breaking appliance: Fixed/removable tongue crib or spurs (prevents tongue interposition and digit sucking)
2. Often self-corrects once habit is eliminated

1. High-pull headgear: Intrudes upper molars; counteracts posterior vertical growth
2. Posterior bite blocks (vertical control plate): Blocks eruption of posterior teeth; allows anterior dentoalveolar growth
3. Functional appliance modified for open bite
4. TAD-assisted intrusion of posterior teeth (newer approach)

1. Posterior molar intrusion using TADs (mini-screws in palate): Most stable surgical-alternative
2. Box elastics: Extrude anterior teeth
3. Accentuated Curve of Spee archwire: Relative extrusion of anteriors

1. Orthognathic surgery: Superior repositioning of posterior maxilla (Le Fort I with impaction); autorotates mandible and closes anterior open bite
   • Most stable surgical solution for skeletal open bite

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48. Clinical Features of Cleft Lip and Palate [2M]

• Unilateral (most common: left side) or bilateral
• Spectrum: Notch in vermilion → incomplete (not reaching nostril sill) → complete (reaches nostril floor)
• Alar base widened and distorted on cleft side
• Nasal tip deflects to cleft side (unilateral)
• Bilateral: Nasal tip broad and flat; premaxilla protrusive
• Philtrum may be shortened or absent

• Primary palate: Anterior to incisive foramen (lip + alveolus)
• Secondary palate: Posterior to incisive foramen (hard + soft palate)
• Submucous cleft: Bifid uvula; zona pellucida; notching of posterior hard palate (palpable)
• Nasal regurgitation of food/liquids
• Hypernasal speech + VPI (velopharyngeal incompetence)
• Recurrent otitis media (Eustachian tube dysfunction due to abnormal levator veli palatini)
• Hearing loss (conductive)
• Feeding difficulties in neonates (cannot generate negative pressure for suction)

• Missing lateral incisors (most common - in cleft area)
• Supernumerary teeth adjacent to cleft
• Malposed/rotated teeth near cleft
• Narrow, constricted upper arch
• Class III dental/skeletal tendency (maxillary growth restriction after repair)
• Posterior crossbite
• Scarring after surgery affecting growth

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49. Effect of Drugs on Orthodontic Treatment

• Patients on bisphosphonates: Inform orthodontist; significantly compromised treatment; ONJ risk with any dental surgical procedure
• NSAIDs: Avoid chronic use during active treatment; occasional use for pain acceptable
• Phenytoin/cyclosporine/nifedipine users: Periodontal treatment before orthodontics; may need gingivectomy

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50. Deep Bite

1. Dentoalveolar deep bite: Over-erupted upper and/or lower incisors; no skeletal component
2. Skeletal deep bite: Reduced lower anterior facial height; hypodivergent (low angle) facial pattern
3. Traumatic deep bite: Lower incisors contact palatal mucosa or periodontal tissues of upper incisors

• Hypodivergent skeletal pattern (low angle, low FMA)
• Over-eruption of anterior teeth
• Under-eruption of posterior teeth
• Strong bite force / hyperactive musculature
• Loss of posterior teeth (loss of vertical stop)
• Class II div 2 malocclusion (retroclined upper incisors, deepened overbite)

• Excessive upper incisor overlap of lower (>3 mm)
• Reduced lower anterior facial height
• Square facial pattern; broad mandible
• Deep mentolabial sulcus
• In traumatic deep bite: Palatal mucosa ulceration or gingival stripping of lower incisors
• Class II div 2: Retroclined central incisors; proclined lateral incisors

• Anterior bite plane (flat bite plane) in removable appliance:
  • Contacts only upper incisors
  • Posterior teeth not in contact → posterior eruption; anterior teeth intrude relatively
  • Effective in growing children (2-3 mm improvement/year)
• Clark's Twin Block: Natural bite opening effect with functional Class II correction

1. Utility arch (Burstone/Ricketts): 0.016×0.022 SS; intrudes upper incisors directly; force 15-20 g
2. Segmented arch mechanics: Three-piece arch with intrusion segments; precise force control
3. Reverse curve of Spee in lower arch: Relative intrusion of lower anteriors + extrusion of premolars
4. Accentuated curve of Spee in upper arch: Intrudes upper anteriors
5. TADs (mini-screws): Absolute intrusion without anchorage loss; optimal control

• Superior repositioning of maxilla (Le Fort I) for severe skeletal deep bite with reduced LAFH
• Genioplasty for chin protrusion

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SURGICAL ORTHODONTICS, RETENTION & RELAPSE

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51. Retention and Relapse - Theorems of Retention [9M]

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52. Relapse in Orthodontics

1. Periodontal/Gingival fiber recoil:
   • Elastic supracrestal gingival fibers take 12+ months to remodel
   • Principal cause of rotational relapse
   • Transseptal fibers maintain interdental contacts; may return teeth to contact
2. Growth:
   • Continued mandibular growth (especially in Class III) after treatment causes relapse
   • Late mandibular growth spurt in males (up to early 20s)
3. Occlusal factors:
   • Poor intercuspation
   • Interferences driving teeth back
   • Lack of Class I stop
4. Muscle imbalance:
   • Tongue, lip, cheek pressures not in balance at new position
   • Particularly for expanded arches
5. Incomplete treatment:
   • Uncorrected rotations, incomplete root torque, poor arch coordination
6. Third molar pressure:
   • Controversial; current evidence does not support wisdom teeth as significant cause of crowding relapse

• Rotations (especially round-rooted teeth)
• Arch width expansion
• Lower incisor proclination
• Diastema closure
• Class III correction
• Open bite correction

• Pericision for rotations
• Appropriate retention design
• Patient compliance with retainer wear
• Permanent retention for high-risk cases

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53. Fixed Retainers

• Passive orthodontic devices bonded permanently to the lingual surfaces of teeth to prevent relapse

1. Multi-strand (twisted/braided) wire retainer:
   • Most commonly used
   • Wire: 0.0195" (or 0.175 mm) multi-strand braided SS wire (e.g., Penta-One, Tru-Chrome)
   • Bonded to lingual surface of each tooth individually (canine-to-canine or 4-4)
   • Flexible: Allows physiologic tooth movement
2. Solid round wire:
   • 0.017" or 0.0175" SS
   • Bonded only to canines (passive canine-to-canine)
   • Allows some interdental mobility
3. Fiber-reinforced composite (FRC) retainer:
   • Polyethylene/glass fiber strip embedded in composite
   • Good aesthetics; rigid

• Lower canine to canine (3-3): Most important; prevents lower incisor relapse
• Upper canine to canine (3-3): For diastema closure or upper incisor instability

• Diastema closure (mandatory)
• Significant rotation correction
• Lower incisor proclination correction
• Upper or lower arch expansion
• Missing teeth (space maintenance)
• Periodontally compromised teeth

• Continuous 24-hour retention
• No compliance needed
• Excellent long-term results

• Plaque accumulation; calculus formation
• Flossing difficulty (floss threader required)
• Periodontal risk if oral hygiene poor
• Wire breakage (debond); must be monitored regularly
• Cannot be worn during some MRI scans

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54. Micro-Implants (TADs) in Orthodontics

1. Mini-screws (most common): 1.2-2.0 mm diameter; 6-12 mm length; titanium alloy
2. Mini-plates (Skeletal anchorage System): Plate + screws; for greater force
3. Palatal implants: Placed in mid-palate; Straumann system

• Interradicular bone between roots (most common): Between 2nd premolar and 1st molar (upper buccal most common)
• Anterior palate (para-median)
• Mid-palate (palatal implants)
• Retromolar region
• Mandibular symphysis

• Local anesthesia
• Mark interradicular site on OPG
• 1.0 mm pilot hole (optional in soft bone)
• Self-drilling or self-tapping screw inserted with handheld driver
• Load after 2-4 weeks (or immediately if bone quality good)

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55. Theories of Retention

1. Muscle balance (Equilibrium theory): Teeth are stable only where forces of tongue balance forces of lips/cheeks. Position must be within the zone of muscle balance.
2. Bone remodeling theory: Alveolar bone needs time to reorganize around newly positioned teeth. New bone formation fills the socket trail of tooth movement. Minimum 3-6 months of retention allows new bone to organize.
3. Periodontal ligament fiber theory: PDL fibers are stretched during tooth movement and store elastic energy. They slowly reorganize to the new position. This takes approximately 3-4 months.
4. Supra-crestal gingival fiber (elastic fiber) theory: Elastic fibers above the alveolar crest do not remodel quickly; they have memory and attempt to rotate teeth back. These persist for 12+ months - primary reason for rotational relapse. Pericision is the intervention.
5. Growth theory: Post-treatment growth changes the corrected position, particularly in Class II and Class III cases. Retention must continue until growth is complete.
6. Intercanine width theory (Riedel/Little): The lower intercanine width is genetically determined and will return to its original dimension if altered. Expansion of lower arch always relapses.
7. Occlusal theory (cusp interdigitation): Ideal Class I occlusion with good interdigitation provides mutual protection and stability; poor occlusion drives relapse.
8. Third molar theory: Eruption pressure from wisdom teeth pushes anteriors into crowding. Evidence is weak and controversial; some studies show no causal relationship.

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56. Minor Surgical Procedures in Orthodontics

1. Pericision (Circumferential Supracrestal Fiberotomy - CSF):
   • Severs elastic supra-crestal gingival fibers around rotated teeth
   • Reduces rotational relapse by 30-50%
   • Performed at end of active treatment, before debonding
2. Frenectomy:
   • Surgical removal/relocation of prominent frenum
   • Labial frenectomy for median diastema
   • Lingual frenectomy (frenotomy) for ankyloglossia
   • Done AFTER space closure
3. Surgical exposure of impacted teeth:
   • Expose impacted canines (most commonly upper)
   • Techniques: Open eruption technique, closed eruption technique (gold chain traction)
   • Bond bracket/attachment; apply gentle traction with fixed appliance
4. Corticotomy / PAOO (Periodontally Accelerated Osteogenic Orthodontics):
   • Cortical bone cuts + grafting around teeth to be moved
   • Accelerates OTM 3-4 fold (regional acceleratory phenomenon)
   • Reduces treatment time; increases bone volume
5. Distraction Osteogenesis:
   • Gradual bone formation between distracted segments
   • For skeletal discrepancies, cleft cases, mandibular lengthening
6. Removal of supernumerary teeth/odontomes:
   • Mesiodens, supernumerary in cleft area blocking eruption
7. Gingivectomy/Crown lengthening:
   • For gingival hyperplasia (phenytoin, nifedipine, cyclosporine)
   • To expose tooth structure for bracket bonding
8. Alveoloplasty
9. Auto-transplantation: Transfer of premolar to missing incisor site
10. Osseous surgery: For periodontally involved cases; before or after orthodontics

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57. Permanent Retention [2M]

• Retaining corrected tooth positions indefinitely (lifelong retention)
• Necessary when the risk of relapse is too high to allow any period without retention

1. Significant median diastema closure
2. Severe rotation correction (especially upper central incisors)
3. Significant arch width expansion
4. Lower incisor proclination correction
5. Spaces maintained for implants (delayed placement)
6. Periodontally compromised patients (mobile teeth need splinting)
7. Missing teeth (extracted for treatment)
8. Patients treated in late growth/adulthood (bone remodeling slower)
9. Any movement with documented high relapse rate in the individual patient

• Bonded lingual retainer (multi-strand wire): Lower 3-3 most common; upper 3-3 for diastema
• Vacuum-formed retainer (Essix/thermoplastic): Worn nights indefinitely
• Hawley retainer: Worn nights indefinitely
• Fixed prosthesis / FPD: If teeth replaced with bridge (natural retention)

• Check bonded retainer monthly (any broken bond = emergency)
• Floss using a floss threader daily
• Regular dental check-ups every 6 months
• Keep removable retainers in case; wear nightly if bonded retainer fails

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58. Pericision (Circumferential Supracrestal Fiberotomy)

• After rotation correction, elastic supracrestal gingival fibers (especially trans-septal and circular) remain stretched and exert force to return the tooth to its rotated position
• These fibers take 12+ months to remodel on their own
• Severing them at time of debond dramatically reduces this relapse force

1. Local anesthetic injection (buccal and palatal/lingual)
2. A fine-pointed blade (#11 Bard-Parker or specialized pericision knife) inserted into the gingival sulcus
3. Blade advanced to alveolar crest (sulcus depth)
4. Rotated/moved around the full circumference of the tooth (360°)
5. Severs: Circular fibers, gingival fibers above the crest
6. Does NOT sever: Alveolar crest fibers, PDL proper, transseptal fibers below crest
7. No suturing required; minimal bleeding; heals in 1-2 weeks

• Significant reduction in rotational relapse (studies show 50-70% reduction)
• Best for: Maxillary central incisors (most prone to rotational relapse); canines
• Does not eliminate need for retainers

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59. Frenectomy

• Low-attachment, thick, fibrous labial frenum contributing to persistent median diastema
• Positive blanching test (papilla blanches on lip traction)
• Frenum attachment extends to incisive papilla
• Post-orthodontic diastema closure; frenum preventing full closure

1. Excision (Z-plasty): Most common; excise frenum tissue; Z-flap to relocate
2. V-Y plasty
3. Laser frenectomy (CO2 or Er:YAG): No sutures; minimal bleeding; fast healing; increasingly preferred

• Ankyloglossia (tongue tie): Limited tongue mobility; speech problems; difficulty breast feeding in neonates; lower incisor spacing or recession

• Bonded lingual retainer must be in place before or immediately after closure to prevent relapse
• Scar tissue formation at excision site provides some resistance to diastema reopening

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MISCELLANEOUS

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60. Transitional Malocclusion Starting from Birth

• Newborn: Mandible retrognathic (normal - Class II appearance)
• Gingival pads align; mandible grows forward with suckling
• Birth to 6 months: Mandible catches up; straight or mild Class I relationship

• First teeth: Lower central incisors (6 months) → Upper central incisors (8-10 months)
• Normal: Spacing between primary teeth (developmental spacing; "primate" or "anthropoid spaces")
  • Upper: Between upper lateral incisor and canine
  • Lower: Between lower canine and first premolar (deciduous)
• Normal primary occlusion: Flush terminal plane (most common); mesial step; distal step (Class II tendency)
• Normal: Deep overbite in primary dentition; self-corrects

• Physiologic space increases (inter-canine, inter-molar width growth)
• Anterior spacing may increase (jaw growth)
• Attrition/wear of primary teeth (normal and beneficial)

1. Ugly Duckling Stage (Broadbent phenomenon): Ages 8-9 years; upper incisors appear flared laterally with spaces; normal! Caused by unerupted canine pressing on lateral incisor roots; self-corrects when canines erupt.
2. Lower incisor crowding: Permanent incisors are wider than primary incisors; use of leeway space and incisor proclination accommodate them.
3. Increased overjet temporarily as upper permanent incisors erupt.
4. Molar relationship changes: Flush terminal plane → Class I (using primate space/leeway space).
5. Leeway space: (Nance, 1947) = Size of C+D+E vs C+4+5 in each quadrant
   • Upper: ~0.9 mm/side
   • Lower: ~1.8 mm/side
   • Used for Class I correction and incisor alignment

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61. Stress-Strain Curve

• Stress (σ): Force applied per unit cross-sectional area (N/mm² = MPa)
• Strain (ε): Change in length per original length (dimensionless; mm/mm or %)

1. Proportional limit (P):
   • Upper boundary of linear elastic region
   • Below P: Stress and strain are directly proportional (Hooke's Law: σ = E × ε)
   • E = Young's Modulus (slope of line) = stiffness
2. Elastic limit:
   • Maximum stress beyond which permanent deformation occurs
   • Approximately coincides with proportional limit for most metals
3. Yield point / Yield strength (Y):
   • Practical measurement: 0.2% offset method
   • Point beyond which permanent plastic deformation begins
   • Clinically: Upper limit of useful working range for orthodontic wire
4. Ultimate Tensile Strength (UTS):
   • Peak stress the material can withstand before necking begins
   • For orthodontic purposes: Higher UTS = tougher wire
5. Fracture point (F):
   • Wire breaks

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62. Role of Orthodontist in Cleft Lip and Palate Management

• Pre-Surgical Nasoalveolar Molding (PNAM): Custom molding plates worn in infancy; molds alveolar segments, narrows cleft, shapes nasal cartilage; reduces gap before primary lip repair surgery

• Monitor arch development
• Address habits (thumb sucking)
• Correct individual anterior crossbite if present and significant
• Expand constricted upper arch if crossbite present

• Arch expansion: Correct collapsed upper arch in preparation for secondary alveolar bone grafting
• Secondary alveolar bone graft (SABG) timing: Grafting at 8-10 years BEFORE upper canine erupts into cleft area
• Pre-SABG orthodontics: Create space in alveolar cleft area; upright adjacent teeth; level and align
• Post-SABG: Allow canine to erupt through graft

• Comprehensive orthodontic treatment with fixed appliances
• Align all erupted permanent teeth
• Manage missing lateral incisors: Close space (camouflage) or open space (for implant)
• Correct arch form discrepancy

• Decompensate dental compensations (remove tilting that was compensating for skeletal discrepancy)
• Coordinate arches
• Create surgical model that shows true skeletal discrepancy
• Usually 12-18 months before surgery

• Finish and detail
• Correct residual tooth position discrepancies
• Establish ideal occlusion

• Fixed lingual retainers
• Removable retainers

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63. Ideal Requirements of Orthodontic Wire [2M]

1. High springback - large elastic range; recovers original shape after deflection; key for initial alignment
2. Low stiffness (low spring rate) - delivers light continuous forces; inverse of modulus of elasticity × cross-section
3. Good formability - can be bent into complex shapes without fracturing; important for loops
4. High resilience - large area under elastic portion of stress-strain curve; stores and releases energy
5. Good weldability/solderability - for SS and Elgiloy; to attach accessories
6. High biocompatibility - non-toxic, non-irritant; suitable for intraoral use
7. High corrosion resistance - resists oral environment (saliva, pH changes, temperature); Cr2O3 passive layer in SS
8. Low surface friction - smooth surface texture reduces friction in sliding mechanics
9. Sufficient stiffness in finishing stages - SS needs to be stiff enough for precise tooth positioning
10. Available in multiple cross-sections - round, square, rectangular; various diameters
11. Predictable and consistent - uniform material properties; standardized manufacturing
12. MRI safety - desirable; NiTi is MRI safe; SS causes artifacts

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64. Kernahan's Stripped Y Classification

• The letter Y is the visual representation:
  • Two upper arms of the Y = left and right segments of the primary palate (lip and alveolus anterior to incisive foramen)
  • Stem of the Y = the secondary palate (hard and soft palate posterior to incisive foramen)
• The Y is divided into 9 numbered segments

• Does not capture severity/width of cleft
• Does not note Simonart's bands
• Modified by others (Millard; Kriens LAHSHAL notation adds more detail)

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65. Elgiloy

• Cobalt (Co): 40%
• Chromium (Cr): 20%
• Nickel (Ni): 15%
• Iron (Fe): 15-16%
• Molybdenum (Mo): 7%
• Manganese (Mn): 2%
• Carbon, Beryllium (trace)

• High yield strength (comparable to SS after heat treatment)
• Good corrosion resistance (Cr content)
• Excellent formability (blue/yellow temper)
• Can be soldered and welded
• Available in round and rectangular cross-sections

• Complex loop mechanics (Begg technique closing loops)
• Retainer wires
• Auxiliary springs
• Headgear inner bows
• Transpalatal arches (TPA)
• Lingual arches

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66. Shape Memory Wires

• At constant temperature (body temp), wire transforms from martensite to austenite under stress
• On the stress-strain curve: A flat plateau appears (stress-induced transformation zone)
• Wire delivers CONSTANT force over a LARGE deflection range
• When stress removed: Reverts to austenite; "remembers" shape
• Examples: Superelastic NiTi (GAC, Ormco), CuNiTi

• Wire is soft and flexible at low temperature (martensite phase)
• At body/mouth temperature, transforms to austenite phase → becomes stiff and delivers force toward memorized shape
• Transition temperature (Af) engineered to be just below mouth temperature
• Examples: Copper NiTi 27°C, 35°C, 40°C; Neo-Sentalloy; ThermaFlex

1. Initial alignment archwires: Insert flexible at room temp; activates at mouth temp; delivers light constant force
2. Copper NiTi 35°C: Can be refrigerated for easier insertion in tight cases; activates immediately intraorally
3. Excellent for first appointment in heavily crowded cases (large activations tolerated without force peaks)
4. Low load-deflection rate: Patients experience less pain

• Cannot be bent (clinically unusable for loops)
• Cannot be soldered or welded
• More expensive than SS
• Force cannot be precisely titrated by clinician (pre-programmed by manufacturer)

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67. Spot Welding

• Joule heating: Q = I² × R × t
• Two copper electrodes clamp metal pieces together under pressure
• Brief pulse of high-ampere current passes through
• High electrical resistance at the metal-metal interface generates intense heat
• Metals fuse locally at the clamped point

• Spot welding machine (e.g., Miller spot welder, Unitek spot welder)
• Copper alloy electrode tips (various shapes for different attachments)
• Timer and current controls

1. Attaching brackets to molar/premolar bands
2. Attaching buccal/lingual tubes to bands
3. Attaching cleats, hooks, and accessories to bands
4. Joining band material (band forming)
5. Attaching lingual buttons or sheaths

• Speed (1-2 second operation)
• No flux or solder required
• Strong, consistent joints
• No heat spread (localized; does not damage adjacent areas)
• Suitable for thin band material

• Cannot join dissimilar metals effectively
• Requires dedicated equipment
• Cannot repair or modify after welding (unlike soldering)
• Not suitable for all orthodontic joins

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68. Composition of 18-8 Stainless Steel

• High corrosion resistance (Cr₂O₃ passive layer)
• Good tensile strength (1400-1800 MPa)
• Acceptable springback
• Solderable (hard solder)
• Weldable (spot and resistance)
• Biocompatible (Ni can cause allergy in sensitive individuals)
• Most widely used material for archwires, bands, clasps, and appliance components

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69. Flux and Anti-Flux

1. Chemically dissolves/removes the oxide layer from metal surfaces
2. Prevents new oxide formation during heating (excludes oxygen)
3. Lowers surface tension; allows molten solder to wet and flow on metal surface
4. Enables metallurgical bond between solder and base metal

• Borax-based paste flux: Most common; effective for stainless steel; applied as thick paste
• Fluoride-containing flux (Easy-Flo flux): For silver soldering; aggressive; removes heavy oxides
• Liquid flux: Water-based; less viscous; for flowing solder joints
• Self-fluxing solder (flux-core): Flux incorporated within solder wire

• Must be cleaned off completely after soldering (fluxes are corrosive if left)
• Clean with water; neutralize with baking soda solution
• Fluoride fluxes require careful handling (toxic if inhaled/ingested)

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1. Rouge (iron oxide, Fe₂O₃) mixed with water or alcohol: Most traditional; applied as paste; fired on before soldering
2. Graphite pencil marks: Applied directly on metal; easy to use
3. Nail polish/lacquer: Applied before soldering; burns off harmlessly
4. Typodont separator/silicone: Applied to acrylic or nearby areas
5. Whiteout (correction fluid): Sometimes used
6. Commercial anti-flux solutions

• Applied to acrylic baseplate areas adjacent to the solder joint
• Applied to tubes/brackets that should not be covered with solder
• Applied to surfaces of a wire that extend beyond the joint

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70. Ni-Ti Wires

1. Martensitic NiTi (conventional): Work-hardened; no superelasticity; Unitek Nitinol
2. Superelastic NiTi: Austenitic-active; flat force-deflection plateau; GAC, Ormco
3. Thermally activated NiTi (TANT):
   • Copper NiTi 27°C, 35°C, 40°C (Ormco)
   • Neo-Sentalloy (GAC): Gentle, moderate, standard force options
   • ThermaFlex
4. Chinese NiTi: Martensitic; highly flexible
5. Graded force NiTi: Different cross-sections in anterior vs posterior segments

• 0.012 NiTi or CuNiTi → 0.014 NiTi → 0.016 NiTi → 0.018 NiTi → 0.016×0.022 NiTi → 0.019×0.025 SS → 0.019×0.025 TMA (optional) → 0.019×0.025 SS (finishing)

• Superelastic: Light continuous forces; large activation range
• Excellent initial alignment
• Low force/deflection rate = comfortable for patients
• MRI safe (non-ferromagnetic)
• Temperature-activated types work with body temperature

• Cannot be bent, cut, or soldered
• More expensive than SS
• Cannot be used for loop mechanics
• Force not adjustable by clinician after manufacturing

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