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ORTHODONTICS - COMPLETE EXAM ANSWERS

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LONG QUESTIONS

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Q1. Enumerate Various Methods of Classification of Malocclusion. Discuss Ackerman-Proffit Classification in Detail. ('17)

Definition of Malocclusion

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Enumeration of Classification Systems

1. Angle's Classification (1899) - most widely used
2. Dewey's Modification of Angle's Classification (1915)
3. Simon's Classification (1922) - Gnathostatic cast classification
4. Lischer's Modification (1912)

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Ackerman-Proffit Classification (1969) - In Detail

Rationale

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The Five Steps / Venn Diagram Approach

• Crowding vs. spacing
• Rotations, tipping
• Assessed by arch length-tooth material discrepancy

• Straight (normal)
• Convex (retrognathic mandible / Class II tendency)
• Concave (prognathic mandible / Class III tendency)

• Posterior crossbite (uni- or bilateral)
• Buccal non-occlusion (scissors bite)
• Assessed in both arches

• Class I, II, or III molar relationship
• Includes overjet assessment
• Dental and skeletal A-P discrepancy

• Increased overbite / deep bite
• Decreased overbite / open bite
• Skeletal vs. dental vertical discrepancy

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Venn Diagram Representation

        Profile
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    [Transverse] ∩ [A-P] ∩ [Vertical]
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        Alignment

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Advantages of Ackerman-Proffit Classification

1. Comprehensive - covers all three planes of space
2. Includes soft tissue profile assessment
3. Addresses crowding/spacing explicitly
4. Logical and systematic
5. Better treatment planning guide than Angle's
6. Can describe mixed/complex malocclusions accurately
7. Basis for modern computerized orthodontic records

Disadvantages

1. More complex, less easy to memorize
2. Lacks numerical/quantitative severity index
3. Not universally adopted in clinical practice
4. Does not indicate specific treatment mechanics

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Q2. Classify Etiologic Factors of Malocclusion. Describe Environmental Factors in Detail. ('10)

Classification of Etiological Factors

A. General/Intrinsic Factors (Hereditary)

1. Heredity
2. Congenital defects (cleft palate, cerebral palsy, etc.)

B. Local/Extrinsic Factors

1. Abnormal pressure habits
2. Premature loss of deciduous teeth
3. Prolonged retention of deciduous teeth
4. Late eruption of permanent teeth
5. Abnormal eruption path
6. Ankylosis
7. Dental caries
8. Iatrogenic factors

C. General/Environmental Factors

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Environmental Factors in Detail

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1. Prenatal Environmental Factors

• Deficiencies of vitamins A, D, C affect jaw growth and tooth development
• Severe malnutrition can affect calcification of teeth

• Intrauterine infection - causes enamel hypoplasia, abnormal tooth morphology
• Can affect jaw development during embryonic period

• Thalidomide - causes severe craniofacial defects
• Tetracycline - causes discoloration, enamel hypoplasia (post-birth but same principle)

• Abnormal position of fetus - can cause mandibular retrognathia (retrognathic mandible due to chin pressed against chest)
• Torticollis, facial asymmetry from abnormal in-utero positioning

• Birth trauma to TMJ - can cause condylar damage, leading to growth asymmetry

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2. Postnatal Environmental Factors

• Vitamin D deficiency - Rickets: delayed tooth eruption, enamel hypoplasia, arch constriction
• Vitamin C deficiency - Scurvy: periodontal disease, loose teeth
• Vitamin A deficiency - affects odontoblast function, abnormal dentin

• Hypothyroidism: delayed eruption, retained deciduous teeth, mandibular underdevelopment
• Hyperthyroidism: accelerated eruption, early loss of deciduous teeth
• Hypopituitarism: delayed eruption, crowding (teeth large relative to small jaws)
• Hyperpituitarism (acromegaly): prognathic mandible, Class III malocclusion
• Hypoparathyroidism: enamel hypoplasia, delayed eruption

• Prenatal/early postnatal infections affect enamel matrix formation
• Syphilis: Hutchinson's incisors (screwdriver-shaped), mulberry molars
• Fever during enamel formation: enamel hypoplasia (chronological hypoplasia)
• Osteomyelitis of the jaw: can affect condyle, disturb growth

• Hypophosphatasia: premature exfoliation of primary teeth
• Gaucher's disease, histiocytosis: bone resorption, tooth displacement

• Trauma to primary teeth - intrusion, dilaceration of permanent tooth bud
• Trauma to condyle - ankylosis, asymmetric jaw growth
• Birth forceps injury - can depress mandibular growth on one side

• Enlarged adenoids - forces mouth breathing
• Mouth breathing:
  • Tongue drops from palate
  • Buccinator pressure not counteracted by tongue
  • Narrow, high-arched palate (Gothic arch)
  • Increased lower anterior face height (vertical growth pattern)
  • Proclined upper anteriors
  • Open bite tendency
  • "Adenoid facies": open mouth, retrognathic mandible, narrow alar base

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3. Functional Influences

• Thumb/finger sucking, lip biting, tongue thrusting, bruxism

• Infantile/visceral swallow persisting beyond age 2-3 years
• Tongue placed between teeth during swallow - causes anterior open bite

• Space loss leading to mesial drift of adjacent teeth
• Ectopic eruption of permanent successors

• Blocks permanent tooth eruption path
• Causes ectopic position

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Q3. Local Factors Responsible for Malocclusion

Classification of Local Factors

1. Anomalies of Number

• Most common: mesiodens (between upper central incisors)
• Causes: diastema, impaction of adjacent teeth, rotations, delayed eruption
• Other sites: paramolar (between molars), distodens (distal to third molar)
• Leads to displacement and crowding

• Most commonly missing: upper lateral incisors, lower second premolars, third molars
• Results in spacing, tipping of adjacent teeth, over-eruption of opposing teeth
• Can cause midline shift

2. Anomalies of Tooth Size

• Large teeth relative to jaw size
• Causes: crowding, overlapping

• Small teeth (peg lateral) relative to arch size
• Causes: spacing, diastemata

• Size discrepancy between maxillary and mandibular teeth
• Results in spacing or overjet/overbite problems

3. Anomalies of Tooth Shape

• Dilaceration - bent root, ectopic eruption
• Gemination, fusion - creates wide tooth, spacing/crowding
• Taurodontism - may contribute to premature loss
• Dens invaginatus / dens evaginatus

4. Abnormal Labial Frenum

• Hypertrophic/low-attached maxillary labial frenum
• Causes persistent midline diastema
• Blanch test (ischemization test) positive
• Indication for frenectomy

5. Premature Loss of Deciduous Teeth

• Results in space loss due to mesial drift of posterior teeth
• Most critical: loss of second deciduous molar (greatest space loss)
• Extent depends on: age at loss, tooth lost, arch (lower > upper for space loss)
• Can be managed by space maintainers

6. Prolonged Retention of Deciduous Teeth

• Causes ectopic eruption (classically lower permanent incisors erupt lingual to retained primary incisors - "double row" of teeth)
• Ankylosed primary teeth - submerged appearance, tipping of adjacent teeth

7. Delayed Eruption

• General: hypothyroidism, rickets, hypopituitarism
• Local: supernumerary teeth, cysts, dense fibrous tissue overlying erupting tooth, ankylosed primary predecessor

8. Abnormal Eruption Path

• Ectopic eruption of upper first permanent molar - resorbs distal root of upper second deciduous molar
• Ectopic eruption of upper canine (most common cause of impaction after third molars)

9. Ankylosis

• Fusion of cementum/dentin to alveolar bone
• "Submerged" deciduous molar - infraocclusion
• Adjacent teeth tip into the space; opposing tooth over-erupts

10. Dental Caries

• Interproximal caries - arch length loss, mesial drift
• Large carious cavities - food impaction, tooth displacement
• Chronic periapical infection - can affect development of permanent successor

11. Iatrogenic Factors

• Poorly designed restorations (premature contacts, incorrect contour)
• Premature extraction without space maintenance
• Overextended orthodontic treatment causing root resorption
• Improperly designed removable appliances

12. Soft Tissue Abnormalities

• Ankyloglossia (tongue tie) - limits tongue movement, may contribute to anterior open bite
• Scars from cleft repair
• Enlarged tonsils/adenoids (see environmental factors)

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Q4/Q5. Angle's Classification of Malocclusion, Dewey's Modifications, and Limitations ('21, '07, '22)

Angle's Classification (1899)

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Class I (Neutroclusion)

• Molar relationship: Normal - mesiobuccal cusp of upper first molar occludes in the buccal groove of lower first molar
• Problem: Lies within the arches (crowding, spacing, rotations, labial/lingual displacement of teeth)
• Skeletal bases are often normally related
• Most common classification

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Class II (Distoclusion)

• Molar relationship: Lower first molar is positioned distal to its normal position (or upper molar is mesial)
• The mesiobuccal cusp of upper first molar occludes anterior to the buccal groove of the lower first molar

• Upper incisors are proclined (increased overjet)
• Associated with: increased overjet, deep bite, convex profile
• Hyperdivergent or normal vertical pattern
• Often associated with lip incompetence, mouth breathing, thumb sucking

• Upper incisors are retroclined (reduced overjet)
• Upper laterals are often proclined and overlapping centrals
• Associated with: increased overbite (deep bite), square lower arch
• Hypodivergent facial type
• Strong lower lip activity

• Class II on one side, Class I on the other
• Asymmetric molar relationship
• Dental or skeletal asymmetry

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Class III (Mesioclusion)

• Molar relationship: Lower first molar is positioned mesial to its normal position
• The mesiobuccal cusp of upper first molar occludes in the interdental space between lower first and second molars (or further back)
• Associated with: prognathic mandible or retrognathic maxilla, anterior crossbite, concave profile
• Reverse overjet (negative overjet)

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Dewey's Modifications of Angle's Classification (1915)

Modifications to Class I

Modifications to Class III

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Lischer's Modification (Nomenclature)

• Mesioversion - tooth displaced mesially
• Distoversion - tooth displaced distally
• Labioversion / Buccoversion - toward lips/cheek
• Linguoversion - toward tongue
• Infraversion - below occlusal plane
• Supraversion - above occlusal plane
• Torsiversion - rotated
• Transversion - tooth in wrong position in arch

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Merits of Angle's Classification

1. Simple, easy to understand and use clinically
2. Universally accepted - common language for orthodontists worldwide
3. Based on a reliable anatomical landmark (first permanent molar)
4. Provides a starting framework for treatment planning
5. Historically important - led to the development of the specialty

Demerits / Limitations of Angle's Classification

1. Ignores skeletal pattern - does not distinguish between dental and skeletal malocclusion
2. Ignores the vertical plane - no mention of deep bite or open bite
3. Ignores the transverse plane - no mention of crossbites
4. Ignores soft tissue profile - no assessment of lips, face
5. Molar relationship assumed constant - if upper molar is congenitally missing or extracted, classification fails
6. No consideration of crowding or spacing within Class I
7. Does not assess individual tooth anomalies in number, size, or shape
8. Three-dimensional assessment lacking - purely sagittal
9. No treatment indication - same classification can have very different treatment needs
10. No severity grading - cannot quantify severity of malocclusion
11. Racial/ethnic bias - based on Caucasian population norms
12. Does not consider the role of muscles and soft tissues

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Q6. Role of Musculature in Etiology of Malocclusion. Wolff's Law. Benninghoff's Trajectories. (2019)

Role of Musculature in Etiology of Malocclusion

A. The Neutral Zone (Zone of Equilibrium)

• Normal balance: Tongue pushes outward; lips and cheeks push inward - equilibrium
• Imbalance in either direction causes malocclusion

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B. Tongue Muscles

• Tongue thrusting: Forward thrust during swallowing pushes anteriors forward/apart → anterior open bite, proclined incisors, increased overjet
• Macroglossia: Large tongue → generalized spacing, Class III tendency, open bite
• Microglossia: Small tongue → crowding, narrow arch
• Ankyloglossia: Restricted tongue → anterior open bite, lower incisor spacing
• Low tongue posture (as in mouth breathers): leaves palate unsupported → narrow high-arched palate

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C. Lip and Cheek Muscles

• Maintains anteriors in position
• Hyperactive lower lip (as in Class II Div 2): retroclination of upper centrals with proclination of laterals
• Lip trap (Class II Div 1): lower lip trapped behind upper anteriors → increases overjet, retroclination of lower anteriors
• Hypotonic lips: Poor lip seal → mouth breathing, proclined anteriors

• Forms a functional sling around posterior teeth
• Limits arch expansion
• In mouth breathers: buccinator acts without counterbalancing tongue → narrow arches, crossbite

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D. Masticatory Muscles

• Strong masseter: promotes horizontal growth, Class II tendency
• Weak masticatory muscles: vertical growth pattern, anterior open bite

• Anterior fibers: retrude mandible
• Hyperactive temporalis + strong masseter: deep bite, Class II

• Opens and protrudes mandible
• Dysfunction can cause TMJ problems

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E. Suprahyoid and Infrahyoid Muscles

• Act as a "functional matrix" for mandibular growth
• Downward and forward pull on the mandible
• Imbalance can affect vertical facial height

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F. Functional Matrix Theory (Moss, 1962)

• Bone grows in response to soft tissue functional matrices (muscles, nerves, vessels)
• Bone is secondary - muscles and soft tissues are primary determinants
• Change the muscle function → change the skeletal pattern
• Basis for functional appliance therapy

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Wolff's Law of Transformation of Bone (1892)

"Every change in the function and form of a bone, or of its function alone, is followed by certain definite changes in its internal architecture and equally definite secondary alteration in its external conformation, in accordance with mathematical laws."

1. Bone is deposited where stresses are greatest (compression/tension)
2. Bone is resorbed where stresses are absent or reduced
3. The trabecular pattern of bone aligns with lines of principal stress
4. If stresses are altered, the trabecular pattern changes accordingly
5. This principle applies to both cortical and cancellous bone

• Tooth movement is possible because bone responds to continuous low-level forces
• Pressure side: osteoclastic resorption
• Tension side: osteoblastic deposition
• Basis for all orthodontic tooth movement

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Benninghoff's Trajectories (Stress Trajectories / Archtectural Lines)

In the Mandible:

1. Compressive trajectories: Run from condyle head, through ramus and corpus, to symphysis - represent compressive forces during mastication
2. Tensile trajectories: Run from the alveolar process and inferior border - represent tensile forces
3. These two systems cross at approximately right angles (orthogonal pattern)
4. At the symphysis, compressive and tensile lines meet and curve
5. The mandibular canal runs along the neutral axis between the two systems

In the Maxilla:

1. Nasomaxillary buttress - from canine region upward to nasofrontal suture
2. Zygomaticomaxillary buttress - from first molar region to zygomatic arch
3. Pterygomaxillary buttress - posterior pillar via pterygoid plates

• Heavy orthodontic forces that exceed physiologic levels can disrupt these trajectories
• Optimal force levels preserve the trabecular architecture while causing productive bone remodeling
• Understanding these patterns helps in planning orthopedic forces (e.g., headgear, protraction facemask)

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Q7. Define Habits in Orthodontics. Abnormal Muscular Habits. Management of Simple Tongue Thrust. (2020s)

Definition of Habits (in Orthodontics)

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Classification of Abnormal Muscular Habits

A. Sucking Habits

• Most common oral habit
• Normal up to age 3 (non-nutritive sucking)
• Beyond age 3-4: can cause malocclusion if persistent
• Effects (depending on intensity and direction):
  • Proclined upper anteriors, retroclined lower anteriors
  • Anterior open bite (localized - "thumb space")
  • Posterior crossbite (due to low tongue + increased buccinator pressure)
  • Increased overjet
  • Narrowing of upper arch
  • Asymmetric open bite if one finger used at angle
• Management: habit-breaking appliances (palatal crib, bluegrass appliance), positive reinforcement, habit-breaking gloves

• Lower lip sucked under upper anteriors
• Causes: proclined upper anteriors, retroclined lower anteriors, increased overjet
• Lower lip sucked between the arches: can deepen the bite

• Buccal mucosa sucked in
• Reduces arch width, may contribute to posterior crossbite

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B. Lip Habits

• Usually lower lip is bitten
• Results: proclined upper anteriors, retroclined lower anteriors, increased overjet
• May cause lip calluses and mentalis strain

• In Class II Div 1, the lower lip becomes trapped behind the proclined upper anteriors during swallowing and at rest
• Self-perpetuating habit - worsens the overjet
• Management: bite plane to disengage the lip, then orthodontic correction

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C. Tongue Thrust (Abnormal Swallowing Habit)

1. Simple tongue thrust (anterior): Tongue thrusts forward between anterior teeth with teeth apart - causes anterior open bite
2. Complex tongue thrust: Involves multiple areas (anterior + posterior sectors)

• Anterior open bite (most characteristic)
• Proclined upper and lower anteriors
• Increased overjet
• Posterior open bite (if complex type)

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D. Mouth Breathing Habit

• Normal nasal breathing bypassed
• Causes: enlarged adenoids, deviated nasal septum, chronic rhinitis, nasal polyps
• Effects: Adenoid facies - narrow, high-arched palate; retrognathic mandible; open mouth posture; proclined upper anteriors; increased lower anterior face height
• Treatment: Address the underlying cause (ENT), then orthodontic correction

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E. Bruxism (Clenching and Grinding)

• Parafunctional habit during sleep (nocturnal bruxism) or waking (diurnal)
• Causes: attrition, TMJ dysfunction, myofascial pain, muscle hypertrophy
• Orthodontic implications: loss of vertical dimension, altered occlusal relationships

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F. Postural Habits

• Head posture: forward head posture increases lower anterior face height, retrognathia
• Sleeping posture: one-sided pressure can cause facial asymmetry in young children

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Management of Simple Tongue Thrust

Step 1: Diagnosis

• Clinical examination: anterior open bite, proclined anteriors
• Confirm by observation of swallowing (lip seal observed; tongue visible between teeth during swallow)
• Distinguish from adaptive tongue thrust (tongue placed between teeth to seal around an existing open bite) vs. primary tongue thrust (habit causes the open bite)
• Primary tongue thrust must be corrected; adaptive tongue thrust may resolve once open bite is corrected

Step 2: Patient Motivation and Education

• Explain to patient and parents the cause and effect relationship
• Motivate patient to correct swallowing pattern voluntarily
• Myofunctional therapy (tongue exercises):
  • "Spot" technique: teach patient to place tongue tip on a designated spot (spot) on palate behind upper anteriors during swallowing
  • Swallowing exercises: practice swallowing with tongue tip up
  • Myofunctional exercises to strengthen tongue muscles

Step 3: Habit-Breaking Appliance

• Palatal crib / Tongue crib: Fixed or removable appliance with metal crib preventing tongue from thrusting forward
• Fixed palatal crib (preferred for compliance): cemented, cannot be removed by patient
• Worn for 6-12 months
• After crib: residual open bite may need orthodontic closure

Step 4: Orthodontic Treatment

• Once habit is broken, residual open bite managed by:
  • Bite blocks / posterior bite planes to allow anterior vertical growth
  • Fixed appliances with vertical elastics
  • In severe skeletal cases: orthognathic surgery

Step 5: Retention

• Long retention needed as tongue thrust may relapse
• Tongue exercises continued during retention

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Q8. Define Malocclusion, Classify Etiological Factors, Describe Local Factors. (2022)

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Q9. Enlist Various Classifications. Discuss Angle's Classification - Modifications, Merits, Demerits. (2022)

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SHORT QUESTIONS

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SQ1. True vs. Pseudo Deep Bite (2018)

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SQ2. Habits as Etiological Factor of Malocclusion (2018)

• Frequency - how often the habit occurs per day
• Duration - total time the habit has been present
• Intensity - force generated
• Direction - where the force is directed

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SQ3. True Deep Bite ('16)

• Genetic/hereditary (strong masticatory muscles)
• Over-eruption of upper and lower anteriors
• Supra-eruption in the absence of posterior support
• Loss of posterior vertical stops
• Class II Division 2 malocclusion (most classic association)

• Increased curve of Spee
• Palatal trauma possible (lower incisors impinging on upper palatal gingiva)
• "Gummy smile" if upper anteriors have over-erupted
• Short, square lower face

1. Tooth of dental origin - due to over-eruption
2. Skeletal - due to reduced lower face height (pseudo deep bite)

• Intrusion arches (utility arch, intrusion mechanics in fixed appliances)
• Bite plane therapy (flat anterior bite plane - allows posterior teeth to erupt and reduce overbite)
• Posterior vertical build-up
• Curve of Spee correction by leveling

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SQ4. Lip Trap ('10)

• In Class II Div 1, upper incisors are proclined with increased overjet
• The lower lip naturally comes to rest behind the proclined upper anteriors
• During swallowing, the lower lip seals against the palatal surface of upper anteriors (not against the lower anteriors as normal)
• This removes the restraining force of the lower lip from the lower anteriors and adds a backward force on lower anteriors

• Self-perpetuating: Increases the overjet further
• Proclines upper anteriors more (lip pushes them forward)
• Retroclinesower anteriors (lip pressure)
• Creates a "moat" between upper and lower anteriors

• Break the lip trap mechanism using an anterior inclined plane or bite plane
• Once overjet is reduced to normal, lower lip naturally moves to correct position
• Oral screen (vestibular screen) can be used

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SQ5. Andrews' Six Keys to Normal Occlusion ('11, '12, 2020s)

Key I - Molar Relationship

• Distal surface of the distobuccal cusp of the upper first molar occludes with the mesial surface of the mesiobuccal cusp of the lower second molar
• Mesiobuccal cusp of upper first molar occludes in the groove between mesial and middle buccal cusps of lower first molar
• Mesiolingual cusp of upper first molar occludes in the central fossa of lower first molar

Key II - Crown Angulation (Tip)

• The gingival portion of the long axis of each crown is distal to the incisal/occlusal portion
• Each tooth is angulated (tipped) mesially
• This ensures proper interproximal contact and maximum posterior tooth contact

Key III - Crown Inclination (Torque)

• Upper anteriors: Positive labial torque (crown labial to root apex)
• Lower anteriors: Slight positive torque
• Posterior teeth (all): Negative torque (crowns lingual to root apex) - progressively more negative from premolars to molars
• Correct torque ensures proper intercuspation

Key IV - Rotations

• Teeth should be free of undesirable rotations
• A rotated molar occupies more space than normal → arch length discrepancy

Key V - Tight Contacts

• No spaces (diastemata) between teeth
• Tight proximal contacts throughout both arches
• Ensures teeth act as a unit (interdental contacts transmit forces)

Key VI - Curve of Spee

• Flat to slightly curved (0 to +1 mm)
• Deep curve of Spee (seen in deep bite) reduces space for upper teeth → crowding
• Flat curve of Spee is the ideal

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SQ6. Pseudo Class III Malocclusion ('12, 2020s, '21)

Differences from True Class III:

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SQ7. Simon's Classification ('11, '10)

Reference Planes:

1. Frankfort Horizontal Plane (orbitale to porion)
2. Orbital Plane (vertical plane through both orbitale, perpendicular to FH)
3. Midsagittal Plane (sagittal midline plane)

Classification:

1. Relation to Frankfort Horizontal Plane (Vertical)

• Infraclusion (Infra-occlusion): Teeth below their normal distance from FH plane (similar to open bite)
• Supraclusion (Supra-occlusion): Teeth above their normal distance from FH (deep bite tendency)
• Normo-occlusion: Normal vertical relationship

2. Relation to Orbital Plane (Anteroposterior)

• Protraction: Teeth are anterior to the orbital plane (Class III tendency)
• Retraction: Teeth are posterior to the orbital plane (Class II tendency)
• Normo-occlusion: Normal A-P relationship

3. Relation to Midsagittal Plane (Transverse)

• Contraction: Teeth displaced toward midline (crowding, narrow arch)
• Distraction: Teeth displaced away from midline (spacing, wide arch)
• Normo-occlusion: Normal transverse relationship

Merits of Simon's Classification:

• Three-dimensional (first classification to address all three planes)
• Relates teeth to skull anatomy
• Useful for cephalometric assessment

Demerits:

• Complex and time-consuming
• Requires gnathostatic mounting of casts
• Not widely used clinically
• Does not describe individual tooth malpositions

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SQ8. Advantage and Drawbacks of Angle's Classification ('06)

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SQ9. Lischer's Modification of Angle's Classification (Nomenclature for Individual Teeth)

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SQ10. Dewey's Classification of Angle's Classification

• Class I Types 1-5: Crowding, proclined anteriors, anterior crossbite, posterior crossbite, mesial drift
• Class III Types 1-3: Both arches proclined (edge-to-edge), lower anteriors retroclined, anterior crossbite

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SQ11. IOTN - Index of Orthodontic Treatment Need (2019)

Two Components:

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Component 1: Dental Health Component (DHC)

• Grade 1 (No need): No malocclusion or negligible malocclusion
• Grade 2 (Little need): Slightly irregular teeth; slight displacement < 1 mm
  • 2a: Overjet 3.6-6mm with competent lips
  • 2b: Reverse overjet 0 to -1mm
  • 2c: Crossbite < 1mm discrepancy
  • 2d: Contact point displacements 1-2mm
  • 2e: Overbite >3.5mm with no gingival contact
  • 2f: Open bite 1-2mm
  • 2g: Less visible hypodontia
  • 2h: Erupting/erupted supernumerary teeth
• Grade 3 (Moderate need): Moderate malocclusion
  • 3a: Overjet 6.1-9mm
  • 3b: Reverse overjet -1 to -3mm
  • 3c: Crossbite 1-2mm discrepancy
  • 3d: Contact point displacements 2-4mm
  • 3e: Overbite >3.5mm with gingival contact
  • 3f: Open bite >2mm, <4mm
• Grade 4 (Great need): Severe malocclusion
  • 4a: Overjet 9.1-12mm
  • 4b: Reverse overjet >3.5mm
  • 4c: Complete posterior crossbite
  • 4d: Contact displacements >4mm
  • 4e: Severe deep bite with palatal trauma
  • 4f: Open bite >4mm
  • 4h: Erupted supernumeraries
  • 4t: Partially erupted/tipped impacted teeth
• Grade 5 (Very great need): Very severe malocclusion
  • 5a: Overjet >12mm
  • 5b: Reverse overjet >3.5mm with masticatory/speech difficulties
  • 5c: Defects of cleft palate/lip
  • 5e: Impeded eruption due to crowding/displacement
  • 5f: Submerged primary teeth
  • 5h: Extensive hypodontia requiring orthodontic treatment
  • 5i: Impacted teeth (except third molars)
  • 5m: Reverse overjet with reported masticatory difficulty
  • 5p: Defects of palate
  • 5s: Submerged primary teeth

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Component 2: Aesthetic Component (AC)

• Scale 1-4: Little/no treatment need (aesthetically acceptable)
• Scale 5-7: Borderline treatment need
• Scale 8-10: Definite treatment need (aesthetically unacceptable)

• Epidemiological surveys (population need assessment)
• NHS funding decisions (UK)
• Prioritizing patients on waiting lists
• Research and audit

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SQ12. Pseudo and True Class III Malocclusion (2021, 2020s)

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SQ13. Local Factors of Malocclusion (2020s)

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SQ14. Keys to Normal Occlusion (2020s)

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QUICK NAVIGATION GUIDE

Long Questions

Short Questions

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• Ackerman-Proffit uses a 5-step Venn diagram (profile + alignment + 3 spatial planes)
• Angle's classification has 3 classes based on the upper first molar as "key to occlusion"
• Dewey added 5 subtypes to Class I and 3 subtypes to Class III
• Wolff's Law: bone remodels in response to stress - basis for orthodontic tooth movement
• Benninghoff's trajectories = stress lines in mandible and maxillary buttresses
• IOTN has 2 components: DHC (Grade 1-5) and Aesthetic (Scale 1-10)
• Pseudo Class III: normal/positive ANB + forward mandibular shift on closure - responds to early treatment
• True Class III: negative ANB + skeletal - may need surgery