Vertical Discrepancies Self-Assessment

Vertical diagnosis & cephalometrics

10 questions, max 10.00 points

Points0.00 of 10.00

Mark each option as correct or not, then click Evaluate. 4 options per question, 0 to 4 may be correct, 0.25 points per correct mark.

Question 1

Which statements about the vertical paradigm and its clinical implications are correct?

A. In a low-angle patient with a deep bite, the treatment strategy relies on molar extrusion combined with mandibular translation.

B. High-angle open-bite cases are considered the easiest category of vertical problem to manage orthodontically.

C. In a high-angle patient, full Class II elastics should be avoided because they carry an extrusive vector on the posterior dentition.

D. The principle that every orthodontic force is inherently extrusive makes vertical control the central organising concept of treatment mechanics.

Question 2

Which statements correctly describe the three long-face subtypes and their distinguishing features?

A. Long-face Type II is caused by environmental factors such as mouth breathing, adenoid hypertrophy, and open-mouth posture.

B. Long-face Type II has a genetic aetiology and is characterised by a short upper lip and VME (vertical maxillary excess with excessive downward maxillary growth).

C. Long-face Type III is defined by a steep mandibular plane angle combined with an anterior (counter-clockwise) rotation of the mandible.

D. Long-face Type III is recognised by a short ramus height, an antigonial notch, a steep mandibular plane, and a backward (clockwise) mandibular rotation.

Question 3

Which statements about the cephalometric toolkit for vertical assessment are correct?

A. A Y-axis (S-Gn to FH) value greater than 65° indicates a clockwise (dolichofacial) growth pattern.

B. An FMA greater than 25° defines a hyperdivergent mandibular plane angle.

C. An MMPA of greater than 27° indicates an open-bite tendency, while an MMPA of less than 27° indicates a deep-bite tendency (Millett).

D. A Jarabak ratio (PFH/AFH) in which the anterior face height is disproportionately large points to a skeletal aetiology for the vertical discrepancy.

Question 4

Regarding cephalometric localisation of open bite, which statements are correct?

A. In a patient with a normal occlusal plane angle but under-eruption of the maxillary and mandibular incisors only, the cause of the open bite is purely anterior and dental.

B. Over-eruption of the maxillary molars localises the open-bite cause to the posterior maxilla.

C. An ODI (Overbite Depth Indicator) below 77° indicates an open-bite tendency.

D. A low APDI (Anterior-Posterior Dysplasia Indicator) below 77° signals a Class II skeletal frame that compounds open-bite management.

Question 5

In cephalometric localisation of deep bite, which statements correctly describe the use of the palatal-plane to occlusal-plane (PP/OP) and mandibular-plane to occlusal-plane (MP/OP) comparison?

A. When the PP/OP angle is greater than the MP/OP angle, the deep bite is localised to either maxillary incisor over-eruption or maxillary molar intrusion.

B. When PP/OP is less than MP/OP, the cause of deep bite is either maxillary molar extrusion or maxillary incisor intrusion.

C. A Jarabak ratio where the posterior fault is dominant points to a postural rather than a skeletal origin of the deep bite.

D. When PP/OP is less than MP/OP, the deep bite is localised to either mandibular incisor over-eruption or mandibular molar intrusion.

Question 6

Which statements about hyperdivergent and hypodivergent thresholds, the Jarabak ratio, and the 1 mm posterior extrusion rule are correct?

A. A saddle angle (NSBa) greater than 135° is associated with a brachycephalic growth pattern.

B. A hyperdivergent pattern is defined by FMA greater than 28°, SN-MP greater than 32°, and is associated with low bite force and an open-bite tendency.

C. One millimetre of posterior molar extrusion produces approximately 2.5 mm of increase in anterior face height (AFH).

D. A lower anterior face height (LAFH) representing more than 35% of total face height is classified as increased, while less than 35% is classified as decreased.

Question 7

Regarding the hypodivergent (brachycephalic) facial pattern, which of the following features are characteristic?

A. FMA <25° and SN-MP <32°

B. Antegonial notch and short ramus height

C. Strong masseter musculature and high bite force

D. Deep overbite tendency with a square jaw form

Question 8

A patient has a normal MP/PP angle (~30°) and cephalometric analysis shows over-eruption of the maxillary molars with normal mandibular molar height. Which statements correctly describe the localisation and clinical implications?

A. The open bite is anterior dental only, caused by incisor under-eruption

B. The posterior maxillary sector is at fault, reflecting a dentoalveolar rather than skeletal aetiology

C. The PP/OP angle will be smaller than the MP/OP angle in this patient

D. Dentoalveolar compensation may mask the severity of any underlying skeletal contribution when relying on facial pattern alone

Question 9

When applying the 'localise-and-quantify' principle to vertical cephalometric diagnosis, which of the following statements are correct?

A. A PP/OP angle greater than the MP/OP angle indicates maxillary incisor over-eruption or maxillary molar intrusion as a contributing cause of deep bite

B. A PP/OP angle smaller than MP/OP points toward mandibular incisor over-eruption or mandibular molar intrusion

C. The occlusal plane normally bisects the interincisal space, making MP/PP approximately 15° in ideal occlusion

D. Jarabak posterior facial height being at fault relative to anterior facial height points toward a skeletal rather than postural vertical problem

Question 10

Regarding the clinical difficulty hierarchy and combined-cause reasoning in vertical malocclusion, which of the following are correct?

A. The easiest vertical problem to treat is a low-angle deep bite of dental origin

B. A high-angle open bite of skeletal origin is easier to manage than a high-angle open bite of dental origin because growth modification is possible

C. The hardest scenario is a high-angle open bite of dental origin, because there is no skeletal lever to exploit and molar intrusion against gravity and muscle is required

D. Because everything in orthodontics is inherently extrusive, vertical control is the organising principle for all treatment decisions

Open bite: etiology & classification

10 questions, max 10.00 points

Points0.00 of 10.00

Mark each option as correct or not, then click Evaluate. 4 options per question, 0 to 4 may be correct, 0.25 points per correct mark.

Question 1

Which statements about the prevalence and natural history of anterior open bite (AOB) are correct?

A. AOB affects approximately 10% of schoolchildren and adolescents.

B. The peak prevalence of AOB occurs at 8–10 years of age in the mixed dentition.

C. Approximately 50% of 3-year-olds display AOB, and most cases resolve once sucking habits cease.

D. AOB persisting into the permanent dentition is likely to self-correct without intervention.

Question 2

Which etiologic factors are cited in the canon as contributing to anterior open bite?

A. Digit or pacifier sucking inhibits alveolar growth and increases AOB risk.

B. Mouth breathing due to nasal or adenoid obstruction forces the tongue downward and promotes posterior over-eruption.

C. Class III skeletal discrepancy is listed as the primary skeletal driver of AOB.

D. Absent lip seal allows tongue posture to unbalance the occlusion.

Question 3

Regarding the classification of open bite into 'false/dental' versus 'true/skeletal', which statements are correct?

A. In false/dental open bite the osseous bases are normal and proclination does not extend beyond the canines.

B. True/skeletal open bite is associated with a hypodivergent, low-angle facial pattern.

C. False/dental open bite involves deformation of the alveolar processes.

D. True/skeletal open bite is characterized by an increased lower facial third and hyperdivergent/dolicho facial type.

Question 4

Which statements about the zonal and subtype classification of open bite are correct?

A. Open bite can be classified by zone as anterior, posterior, or complete.

B. The Early-Tx classification (23.1) describes four types: simple dental, combined, dentoskeletal, and compound.

C. Within the anterior zone, the dental subtype results from an eruption impediment.

D. The severity classification of open bite includes incomplete, simple, complex, and compound grades.

Question 5

Which statements about tongue posture and muscular factors in AOB etiology are correct?

A. Macroglossia primarily causes anterior open bite by restricting incisor eruption, leaving the posterior dentition unaffected.

B. Tongue thrust or aberrant tongue posture resting between the incisors disrupts the muscular equilibrium at the anterior dental arch.

C. Muscular hypotonicity is associated with molar over-eruption and alveolar separation.

D. Genetics and congenital factors can disturb the size, shape, and proportion of skeletal structures, contributing to AOB.

Question 6

Which statements about the Carabelli/Sato definition of anterior open bite (AOB) are correct?

A. The upper and lower incisors fail to overlap vertically.

B. The diagnosis requires a measurable Class II or Class III sagittal discrepancy.

C. The upper and lower occlusal planes do not meet at the incisor level.

D. The definition captures both a dental and a skeletal-plane component of the deformity.

Question 7

Regarding the mouth-breathing pathway to AOB, which of the following correctly describe the sequential mechanism?

A. Mouth breathing directly inhibits alveolar growth of the anterior segment, producing eruption impediment.

B. Nasal or adenoid obstruction forces the tongue into a lowered resting position.

C. The lowered tongue position removes its restraining effect on the posterior alveolus, permitting posterior over-eruption.

D. Mouth breathing increases the lip-seal force, which counteracts the tongue's downward displacement.

Question 8

Which features correctly distinguish the anterior dental subtype of AOB from the anterior skeletal subtype?

A. The dental subtype is associated with an eruption impediment such as a persistent sucking habit blocking normal incisor eruption.

B. The skeletal subtype is characterised by proclined teeth on a normal osseous base, not extending beyond the canine region.

C. Both subtypes show identical dolicho/hyperdivergent growth patterns.

D. The skeletal subtype arises from posterior facial growth that rotates the mandible downward and backward.

Question 9

Regarding the severity classification of open bite (incomplete/simple/complex/compound), which statements are accurate?

A. The severity ladder has three levels: mild, moderate, and severe.

B. Incomplete is the least severe grade on the severity ladder.

C. Compound represents the most severe grade, combining multiple contributing factors or zones.

D. The severity grades apply only to the skeletal (true) open bite, not to the dental (false) type.

Question 10

Which of the following correctly describe the true/skeletal open bite and its relationship to facial morphology?

A. The alveolar processes are deformed, in contrast to the false/dental type where the osseous base is normal.

B. A dolicho/hyperdivergent craniofacial pattern with an increased lower facial third is a hallmark of the true skeletal type.

C. The bite gap in the true skeletal type does not extend beyond the canine region.

D. Posterior mandibular rotation (backward rotation) links the hyperdivergent growth pattern to the development of skeletal AOB.

Open bite: mechanics, Sato & MEAW

10 questions, max 10.00 points

Points0.00 of 10.00

Mark each option as correct or not, then click Evaluate. 4 options per question, 0 to 4 may be correct, 0.25 points per correct mark.

Question 1

Which statements about the Sato Posterior Occlusal Plane (POP) model and its relationship to mandibular rotation are correct?

A. A flatter POP produces forward mandibular rotation and TMJ decompression.

B. In the Sato model, excessive vertical molar eruption steepens the POP and causes Class III prognathism with AOB.

C. Insufficient vertical molar increase prevents the mandible from rotating forward, resulting in a Class II high-angle open bite.

D. A steeper POP drives backward mandibular rotation.

Question 2

Which statements about closure mechanics for anterior open bite are correct?

A. Individual extrusion of upper incisors requires 80–100 g of force per tooth to generate sufficient vertical movement.

B. The scissor effect means that 1 mm of posterior bite-block intrusion produces more than 3 mm of anterior opening.

C. Extrusion closes an open bite at approximately 1 mm per month but is considered an unstable treatment modality.

D. Bypass arches in NiTi or TMA provide full tip and torque control throughout open-bite closure.

Question 3

Which statements about appliances used for posterior intrusion in open-bite treatment are correct?

A. The transpalatal arch (TPA) with intrusion button delivers approximately 80 g of force, with the tongue pressing the disc on swallowing.

B. The acrylic posterior bite block is the preferred appliance for AOB up to 6 mm because it is less violent than the TMA spring intrusion plate.

C. High-pull headgear must be worn at least 24 hours per day and delivers force through the maxillary centre of resistance located 4 mm above the apices of the first molars.

D. TAD and mini-screw AOB splints provide skeletal anchorage for reliable molar and premolar intrusion where conventional mechanics fail.

Question 4

Which statements about MEAW wire specifications, tip-back bends, and elastic protocol for open-bite correction are correct?

A. The standard MEAW wire is 0.016×0.022" Elgiloy used in an 0.018" slot, with L-loops at every interproximal space.

B. Tip-back bends of 2–3° per tooth cumulate to a total of 15–20° across the buccal segments, uprighting posterior teeth and controlling the POP.

C. Vertical elastics for MEAW open-bite cases are placed in the molar zone to maximise posterior extrusive force and accelerate bite closure.

D. Third molars are extracted in all AOB cases treated with MEAW, while premolar extraction is avoided because Sato reports no first premolar extractions in approximately 40 years of practice.

Question 5

Which statements about the Pitts detorque technique and ancillary mechanics for AOB closure are correct?

A. The Pitts technique uses high-torque brackets inverted on upper incisors 1 and 2 to close the AOB by detorquing rather than extruding upper incisors.

B. Class II intermaxillary elastics are recommended in MEAW AOB treatment because they move the anterior segment posteriorly and simultaneously advance the mandible, achieving the desired forward adaptation.

C. Cleats placed behind lower incisors improve tongue posture and assist torque control in the Pitts approach.

D. A lingual arch in the lower dental arch is used to prevent molar extrusion during AOB closure.

Question 6

Regarding the Sato POP model: which statements correctly describe the relationship between posterior occlusal plane (POP) inclination, mandibular rotation direction, and vertical discrepancy class?

A. A steeper POP drives forward mandibular rotation and TMJ decompression.

B. A flatter POP drives forward mandibular rotation and TMJ decompression.

C. In the born-Class-II patient with normal vertical molar increase, the POP flattens, forward rotation converts the Class II to Class I.

D. Excessive vertical increase causes a steeper POP and backward rotation, producing a Class III prognathic AOB.

Question 7

Concerning in-block extrusion bends used in AOB mechanics, which of the following statements are accurate?

A. Each in-block extrusion step is 0.5–1 mm, generating forces of 800–1000 g.

B. Each in-block extrusion step is 1–2 mm, generating forces of 400–600 g.

C. In-block extrusion carries low root-resorption risk because the force is distributed across multiple teeth simultaneously.

D. In-block extrusion carries a risk of both pain and root resorption.

Question 8

Which statements accurately describe the posterior bite block as an intrusion appliance for AOB?

A. Posterior bite block achieves molar intrusion at a rate of 0.25–0.5 mm/month.

B. Posterior bite block is most effective when worn 16 hours per day for 4–6 months.

C. Posterior bite block treatment duration is typically 6–8 months, worn 24 hours per day.

D. Molar intrusion via the posterior bite block causes mandibular autorotation, thereby closing the anterior open bite.

Question 9

Regarding intermaxillary anterior elastics used in AOB treatment, which specifications are correct?

A. Anterior elastics are worn in sizes 3/16–1/4 inch, delivering 2–4 oz of force.

B. Anterior elastics are worn in sizes 1/8–5/16 inch, delivering 2–6.5 oz of force.

C. Anterior elastics must be replaced every 12 hours to maintain adequate force.

D. Anterior elastics are most effective on a round 0.016-inch wire to allow tooth tipping during vertical closure.

Question 10

Which statements correctly describe the rationale and design of MEAW L-loops and the prohibition of molar-zone elastics in AOB treatment?

A. MEAW places L-loops at every interproximal space, enabling independent control of each tooth and regulation of the posterior occlusal plane.

B. Molar-zone elastics are forbidden in MEAW AOB treatment because they cause molar over-eruption, which worsens the posterior discrepancy.

C. MEAW elastics may be placed from the upper molar to the lower premolar in Class II AOB cases to simultaneously correct the AP discrepancy and close the bite.

D. MEAW tip-back bends of 2–3° per tooth accumulate to a total of 15–20° across the buccal segments, uprighting mesially tipped teeth and controlling POP inclination.

Deep bite: etiology & classification

10 questions, max 10.00 points

Points0.00 of 10.00

Mark each option as correct or not, then click Evaluate. 4 options per question, 0 to 4 may be correct, 0.25 points per correct mark.

Question 1

Which statements about overbite norms and their clinical application are correct?

A. Nanda considers an overbite of 25–40% acceptable provided temporomandibular joint function is sound.

B. The Neff norm defines an ideal overbite as 25% of the mandibular incisor crown height.

C. An overbite expressed as a percentage is considered more accurate than a millimeter measurement because of variation in crown length.

D. After bite-opening treatment a freeway space of 2–4 mm must be preserved.

Question 2

Which statements correctly differentiate dental (simple) from skeletal (complex) deep bite?

A. Skeletal deep bite is an acquired condition caused by dental compensations, while dental deep bite is hereditary.

B. Dental deep bite shows a deep curve of Spee and a normal vertical skeleton, whereas skeletal deep bite involves a basal malrelationship.

C. Skeletal deep bite carries a high relapse risk and may present with a two-step occlusion.

D. Class II Division 1 is the most frequent clinical association with deep bite.

Question 3

Which skeletal signs and growth patterns are associated with deep bite of skeletal origin?

A. The brachy pattern is characterised by a counterclockwise mandibular rotation and convergent facial planes.

B. Skeletal deep bite typically presents with a reduced lower anterior facial height, long posterior facial height and a small gonial angle.

C. A short narrow symphysis is the symphyseal hallmark of the skeletal deep-bite pattern.

D. The dental cause of deep bite may involve molar infraocclusion, incisor over-eruption, or a combination of both.

Question 4

Which statements about the neuromuscular basis and consequences of deep bite are correct?

A. The posterior vertical chain consists of the masseter, temporalis and internal pterygoid, an anteriorly positioned and strong chain promotes deep bite.

B. Strong posterior vertical chain muscles promote deep bite by facilitating posterior molar eruption and blocking anterior eruption.

C. Periodontal consequences of traumatic overbite include occlusal overload and circumscribed radiolucencies as described by Roque.

D. TMJ consequences of deep bite include condyles being forced backward and upward in the fossa, disc displacement and clenching.

Question 5

Regarding overbite norms and the hallmark of dental deep bite, which statements are correct?

A. The accepted norm for overbite is 2–3 mm in absolute terms, though percentage measurement is preferred due to crown-length variation.

B. A deep curve of Spee is the hallmark of skeletal (complex) deep bite, reflecting basal vertical discrepancy.

C. A deep curve of Spee is the hallmark of dental (simple) deep bite, arising from the teeth-alveolar unit rather than the skeletal base.

D. Overbite norm of 2–3 mm is reliable as an absolute measure and does not require percentage correction for clinical use.

Question 6

Which consequences follow if freeway space is lost after orthodontic bite opening in a deep bite patient?

A. Loss of freeway space is clinically benign because the neuromuscular system adapts within weeks and re-establishes the original rest position without symptoms.

B. Loss of freeway space creates continuous muscle activity at rest, overloading the posterior vertical chain (masseter, temporalis, internal pterygoid) and risking muscular fatigue and TMJ symptoms.

C. Loss of freeway space results in increased overbite because the mandible rotates counterclockwise to compensate, deepening the deep bite.

D. Freeway space of 2–4 mm must be preserved after bite opening because it represents the physiological rest envelope, violation risks occlusal overload, bruxism, and periodontal sequelae.

Question 7

Which statements correctly describe the mechanism by which posterior eruption is blocked in dental deep bite?

A. A strong anteriorly positioned neuromuscular chain (masseter, temporalis, internal pterygoid) depresses the dentition vertically and prevents posterior teeth from erupting to their full potential.

B. Posterior eruption is blocked primarily by skeletal hyperdivergence, which tilts the occlusal plane and mechanically prevents posterior dental eruption.

C. In skeletal deep bite the mechanism is identical to dental deep bite: molar infraocclusion alone prevents posterior eruption without any basal bone involvement.

D. Molar infraocclusion (failure of posterior eruption) is one of two dental causes of deep bite, the other being incisor over-eruption, both can occur together as a combination cause.

Question 8

Which incisal consequences are correctly attributed to traumatic overbite in the deck?

A. Over-eruption of maxillary posterior teeth, causing a posterior open bite as the anterior segment is forced inferiorly by occlusal overload.

B. Labial migration of mandibular incisors as they are repeatedly displaced by the over-erupted maxillary incisors.

C. Attrition and wear of mandibular incisors from chronic occlusal contact with the palatal surfaces of the maxillary anterior teeth.

D. Maxillary anterior spacing arising from the labial force component of chronic deep-bite occlusal loading on the upper incisors.

Question 9

Regarding periodontal and TMJ consequences of deep bite, which statements are correct?

A. Occlusal overload in deep bite can produce circumscribed radiolucencies at the apex of lower incisors, a finding described by Roque.

B. The TMJ condyle translates anteriorly and inferiorly in deep bite, creating tensile stress on the posterior disc attachment and predisposing to anterior disc displacement.

C. Deep bite forces the condyles backward and upward in the fossa, contributing to clenching habits, disc displacement, and headache.

D. Periodontal bone loss in deep bite follows a generalized horizontal pattern equally distributed around all teeth, unrelated to the specific occlusal loading site.

Question 10

Which statements correctly distinguish skeletal (complex) deep bite from dental (simple) deep bite in terms of prognosis and clinical features?

A. Skeletal deep bite carries a high relapse rate after treatment because the underlying basal malrelationship persists and continues to drive the vertical discrepancy.

B. Skeletal deep bite is hereditary in origin, whereas dental deep bite is acquired, reflecting different etiological pathways.

C. Dental deep bite shows a two-step occlusion (the cuspal premature contact characteristic of skeletal Class II Div 2 pattern) because the alveolar compensation mimics the skeletal pattern.

D. Skeletal deep bite features reduced lower anterior face height (LAFH), long posterior face height (PFH), small gonial angle, and a short broad symphysis, which together distinguish it radiographically from the dental form.

Deep bite: mechanics & forces

10 questions, max 10.00 points

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Mark each option as correct or not, then click Evaluate. 4 options per question, 0 to 4 may be correct, 0.25 points per correct mark.

Question 1

Which statements about the four-lever principle and lip gate for deep-bite treatment are correct?

A. In a patient with incompetent lips, the correct lever choice is to intrude the anterior teeth.

B. 1 mm of posterior molar extrusion produces approximately 1.5 mm of anterior face-height increase.

C. Lever 4 (extrude mandibular posteriors) is the primary choice for Class II Division 2 patients with reduced anterior face height.

D. When lips are competent, the preferred mechanical strategy targets extrusion of the posterior segments rather than intrusion of the anteriors.

Question 2

Which statements about force specifications for deep-bite mechanics are correct?

A. The Gottlieb intrusion target of 15–20 g per incisor is selected specifically to avoid root resorption.

B. A tip-back bend placed in a 0.017×0.025 SS wire at 45° delivers 100–125 g total, equating to 15–20 g per tooth.

C. The reverse-curve continuous arch (Gregoret) is prescribed at 150–200 g because higher forces risk proclination.

D. The Connecticut Intrusion Arch (CIA) uses NiTi continuous force of 40–60 g and achieves approximately 1 mm of intrusion per 6 weeks.

Question 3

Which statements about intrusion appliances and their clinical indications are correct?

A. The anterior bite plane (Hawley) produces scissor-effect bite opening at a ratio of 1 mm posterior extrusion to 1 mm of bite opening.

B. Bite turbos use 6.5 oz elastics changed every 24 hours and are bonded as resin pads on the palatal surfaces of the upper incisors.

C. The Ricketts utility arch (2x4 appliance) combines a 45° tip-back bend with approximately 10–15° of negative torque to achieve pure incisor intrusion.

D. The reverse-curve arch with round wire is contraindicated in brachycephalic patients because it worsens the curve of Spee.

Question 4

Which statements about the Burstone segmented arch and the Gregoret reverse-curve technique are correct?

A. The Burstone segmented arch uses a 0.018×0.022 SS base wire with a helix placed approximately 3 mm anterior to the molar tube to deliver pure anterior intrusion.

B. The round reverse-curve arch provides full root-apex control because the round wire expresses the bracket torque prescription.

C. The Burstone segmented arch is indicated for hyperdivergent patients as its primary use because the posterior bite opening it creates reduces the mandibular plane angle.

D. The Gregoret reverse-curve technique positions the root apices in trabecular bone through negative torque, allowing intrusion without proclination.

Question 5

Which statements about TAD-assisted intrusion and the Alexander/Werneck discipline are correct?

A. The preferred wire for TAD-assisted lower incisor intrusion is TMA 17×25 with a loop tied between the incisors, because it produces less tipping and less root resorption.

B. Continuous heavy forces of 60–80 g per tooth are recommended with TADs to maximize the rate of lower incisor intrusion.

C. The Alexander/Werneck prescription uses a 0.018-inch slot with 0.017×0.025 SS wire, with the posterior anchorage unit being the critical component.

D. The Sydney Intrusion Spring (SIS) delivers approximately 400 g at 5 mm of activation using zygomatic plate anchorage.

Question 6

Which statements about utility arch forces and segmented arch biomechanics are correct?

A. The utility arch delivers approximately 200–250 g to the upper anterior segment because the upper arch has a greater root surface area to stimulate.

B. The lower utility arch generates approximately 80–100 g, calibrated to the recommended 100 g per cm² of root surface area.

C. The intrusion arch with loops incorporates a 5–7 mm vertical loop, delivers 20 g per tooth, and requires negative torque to prevent proclination during the 2–3 month activation period.

D. Distal jet and Beneslider devices use TADs to achieve 1 mm of intrusion per week by applying continuous force directly to the incisor roots.

Question 7

Regarding the four-lever principle, which statements correctly describe the clinical indication of individual levers?

A. Lever 1 (maxillary incisor intrusion) is indicated for patients with incompetent lips, a gummy smile, or a steep mandibular plane.

B. Lever 3 (maxillary posterior extrusion) is the preferred lever for hyperdivergent patients because it reliably closes a deep bite without increasing lower face height.

C. Lever 4 (mandibular posterior extrusion) is applied in Class II Division 2 cases with reduced anterior face height to increase lower face height.

D. Lever 2 (mandibular incisor intrusion) is indicated exclusively for patients with incompetent lip seal.

Question 8

Concerning the growth-direction rule and appliance selection for deep bite, which statements are correct?

A. Anterior bite planes and bite turbos are equally suitable for hyperdivergent and hypodivergent deep-bite patients because disocclusion of the posteriors causes the same skeletal effect in both facial types.

B. In Class II Division 2, bite turbos placed on the palatal surface of the upper incisors help procline retroclined incisors by reversing the incline plane effect.

C. The scissor effect of an anterior bite plane produces 1 mm of anterior bite opening for every 1 mm of posterior extrusion.

D. The growth-direction rule states that bite plane and turbo treatment is favourable in hypodivergent patients and contraindicated in hyperdivergent patients.

Question 9

Regarding the lip bumper and round reverse-curve arch as deep-bite mechanics, which statements are correct?

A. A lip bumper corrects the curve of Spee, distalises molars, and uprights molars, making it suitable for lip-dysfunction cases.

B. A round reverse-curve arch of 300 to 400 g is preferred in dolichofacial (hyperdivergent) patients because its continuous force produces controlled intrusion without increasing face height.

C. The round reverse-curve arch produces pure incisor intrusion with full root control, equivalent to the Burstone segmented arch.

D. A round reverse-curve arch delivering 300 to 400 g of continuous force intrudes and proclines the incisors and is best suited to brachycephalic patients who can tolerate the proclination side effect.

Question 10

Concerning intrusion arch loop mechanics and the distinction between upper and lower intrusion bend forces, which statements are correct?

A. An intrusion arch with loops uses 5 to 7 mm vertical loops delivering approximately 20 g per tooth over 2 to 3 months, and negative torque is essential throughout.

B. The recommended force for an upper intrusion bend is 20 g per incisor, identical to the lower intrusion bend, because symmetrical force produces symmetrical bone response.

C. An upper intrusion bend delivers 30 to 40 g per incisor, while a lower intrusion bend delivers 20 g per incisor with mandatory negative root torque.

D. Distal jet and Beneslider using palatal TADs achieve approximately 1 mm of molar distalization per month, substantially slower than PAOO which achieves approximately 1 mm per week.

Stability, surgery & decision-making

10 questions, max 10.00 points

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Mark each option as correct or not, then click Evaluate. 4 options per question, 0 to 4 may be correct, 0.25 points per correct mark.

Question 1

Which statements about retention and stability of vertical correction are correct?

A. Intrusion is more stable than extrusion when correcting a vertical discrepancy.

B. A removable retainer appliance alone constitutes a true retainer for vertical corrections.

C. Anterior open bite is the least stable of all vertical corrections, with a worse prognosis when skeletal contribution is greater.

D. After open-bite closure, the arch should be left passive to avoid jiggling forces and root resorption risk.

Question 2

Which statements about the master decision gate for vertical correction are correct?

A. In a HIGH-angle patient, extruding the posterior teeth is the preferred first-line strategy to close an anterior open bite.

B. Extruding posteriors by 1 mm increases anterior face height (AFH) by approximately 2.5 mm.

C. In a patient with lip incompetence, the decision gate directs treatment toward anterior intrusion rather than posterior extrusion.

D. A forward rotator does NOT benefit from posterior extrusion because it aggravates the skeletal pattern.

Question 3

Which statements about open-bite surgery and post-surgical stability are correct?

A. Le Fort I maxillary impaction achieves open-bite closure via mandibular autorotation, with the bite closing within hours of surgery.

B. AOB surgical relapse reaches 42.9%, the highest relapse rate, because the occlusal planes were not corrected and molars were not leveled.

C. Non-surgical vertical correction is inherently unstable, with results typically failing within 3–5 years of follow-up.

D. Pre-surgical uprighting of the buccal segment to approximately 15° creates roughly 4.5 mm of space per side for surgical movement.

Question 4

Which statements about the vertical-pull chin cup (VCC) in the growing high-angle, hyperdivergent patient with anterior open bite are correct?

A. The VCC is indicated in growing patients with a steep mandibular plane and increased anterior facial height, where the aim is to restrain vertical growth.

B. The vertical (upward) chin pull promotes forward, upward (counter-clockwise) mandibular autorotation, which helps close the anterior open bite.

C. The VCC works by extruding the posterior teeth, making it the appliance of choice for opening a deep bite in a low-angle patient.

D. The VCC is worn roughly 12 hours per day and is often combined with a posterior bite block (PBB-VPC) to reinforce vertical control.

Question 5

Which statements correctly describe habit, airway, and myofunctional follow-through as prerequisites for vertical stability?

A. Digit-sucking and tongue-thrust habits must be eliminated before attempting definitive vertical correction, because persistent parafunctional forces will drive relapse regardless of appliance design.

B. Airway screening is optional once incisor intrusion has been completed, because the dental change itself resolves the soft-tissue dysfunction.

C. Greater skeletal contribution to an anterior open bite predicts a poorer prognosis for long-term stability, even after successful closure.

D. Leaving the arch passive after space closure and avoiding jiggling forces is essential to prevent root resorption and protect the corrected vertical dimension.

Question 6

Regarding the surgery gate for adult anterior open bite, which criteria and procedural details are correct?

A. Surgery is indicated when AOB exceeds >6 mm, the mandibular plane is steep, and the chin is weak, typically addressed by Le Fort I impaction with or without BSSO.

B. Le Fort I maxillary impaction triggers mandibular autorotation, mechanically closing the bite within hours of surgery rather than through slow bone remodelling.

C. Pre-surgical orthodontic preparation requires light round wires to allow free tooth movement during the surgical phase and avoid placing surgical hooks on the brackets.

D. Surgical relapse rate for AOB is the highest among orthognathic procedures at 42.9%, primarily because occlusal planes were not corrected and buccal segment molars were not adequately levelled before surgery.

Question 7

Which statements about growth direction and its interaction with vertical treatment mechanics are correct?

A. A backward rotator (high-angle, posterior growth direction) benefits from posterior extrusion because it converts unfavourable growth into anterior mandibular rotation.

B. A forward rotator (low-angle, anterior growth direction) benefits from posterior extrusion because the resulting mandibular translation further closes the bite and deepens the vertical overlap.

C. In a backward rotator, posterior extrusion worsens the open bite by rotating the mandible further downward and backward, making extrusion contraindicated in high-angle patients.

D. Growth direction has no influence on the choice between intrusion and extrusion mechanics once the patient has passed peak pubertal growth.

Question 8

Which statements about pre-surgical orthodontic preparation for open-bite surgery are correct?

A. Pre-surgical records including study models should be taken every 6 months during the pre-surgical phase to monitor arch form changes and plan final surgical positioning.

B. The buccal segment should be uprighted approximately 10 degrees, creating roughly 3 mm of space per side before surgery to allow adequate impaction magnitude.

C. Surgical hooks must be placed on incisors only, molar and premolar areas are managed with miniscrews during the surgical phase.

D. Uprighting the buccal segment to approximately 15 degrees creates roughly 4.5 mm of space per side, which is the target value cited for pre-surgical buccal segment preparation.

Question 9

Regarding skeletal deep bite, relapse risk, and the role of bite planes, which statements are correct?

A. Skeletal deep bite carries a high relapse risk because the pattern is hereditary, and a combined surgical-orthodontic approach should be considered in severe adult cases.

B. An anterior bite plane is equally effective and equally indicated in both hypodivergent and hyperdivergent adult patients with deep bite.

C. An anterior bite plane with 0.5 mm posterior clearance is considered favourable in hypodivergent patients because the slight posterior disclusion allows favourable mandibular autorotation.

D. Bite planes are contraindicated in hyperdivergent patients because disclusion of the posterior segments risks increasing anterior face height and worsening the vertical pattern.

Question 10

Which statements about premolar extraction, the Viazis controversy, and lower inter-canine width in deep-bite and open-bite treatment are correct?

A. Premolar extraction is recommended by Viazis specifically to create arch length relief that allows upper incisors to procline and raise the bite.

B. According to Viazis, premolar extraction lingualises the remaining teeth, which deepens the bite and should therefore be avoided in deep-bite cases.

C. Lower inter-canine width must not be expanded at the end of treatment, as expansion of this dimension is a recognised stability risk factor for relapse.

D. In open-bite cases the MEAW protocol routinely extracts the first premolars to create space for posterior intrusion.

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Vertical Discrepancies · Open Bite & Deep Bite

Vertical diagnosis & cephalometrics

Open bite: etiology & classification

Open bite: mechanics, Sato & MEAW

Deep bite: etiology & classification

Deep bite: mechanics & forces

Stability, surgery & decision-making

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