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ABO Orthodontics study materials
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ABO Orthodontics practice questions

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Question 1Orthodontics and Dentofacial Orthopedics

At approximately what age does the pubertal growth spurt peak in height for an average female patient?

  1. Around 17 to 18 years
  2. Around 14 to 15 years
  3. Around 11 to 12 years Correct answer.
  4. Around 8 to 9 years

Explanation

Peak height velocity in females typically occurs near 11 to 12 years, about two years before menarche, and generally precedes the peak in mandibular growth. Recognizing this timing guides when growth modification may be most effective.

Question 2Orthodontics and Dentofacial Orthopedics

Which cephalometric analysis uses the SNA, SNB, and ANB angles to relate the maxilla and mandible to the cranial base?

  1. Ricketts analysis
  2. Tweed analysis
  3. Downs analysis
  4. Steiner analysis Correct answer.

Explanation

The Steiner analysis uses SNA, SNB, and ANB to describe anteroposterior jaw position relative to sella and nasion. These angles are central to classifying skeletal Class I, II, and III patterns.

Question 3Orthodontics and Dentofacial Orthopedics

A patient has an ANB angle of 7 degrees with a normal SNA. This finding most directly indicates which skeletal relationship?

  1. Skeletal Class III tendency
  2. Skeletal Class I pattern
  3. Skeletal open bite tendency
  4. Skeletal Class II tendency Correct answer.

Explanation

An ANB of roughly 2 to 4 degrees is considered Class I; values above that indicate the mandible is positioned posterior to the maxilla, consistent with a skeletal Class II tendency. A normal SNA places the discrepancy at the mandible.

Question 4Orthodontics and Dentofacial Orthopedics

In Angle's classification, a Class II division 1 malocclusion is characterized by which combination?

  1. Distal molar relationship with retroclined central incisors
  2. Normal molar relationship with crowded incisors
  3. Mesial molar relationship with retroclined incisors
  4. Distal molar relationship with proclined maxillary incisors Correct answer.

Explanation

Class II division 1 shows a distal relationship of the mandibular first molar to the maxillary first molar, with maxillary central incisors typically proclined and increased overjet. Division 2 differs by having retroclined central incisors.

Question 5Orthodontics and Dentofacial Orthopedics

Which radiograph is the standard imaging choice for evaluating root angulation, root resorption, and the position of unerupted teeth prior to orthodontic treatment?

  1. Periapical radiograph of a single quadrant
  2. Bitewing radiograph
  3. Lateral cephalometric radiograph
  4. Panoramic radiograph Correct answer.

Explanation

A panoramic radiograph surveys both arches, roots, developing teeth, and the temporomandibular region in one image. It is used to screen for impactions, root resorption, and angulation before appliance placement.

Question 6Orthodontics and Dentofacial Orthopedics

Which archwire property describes the amount of force returned to a given deflection and is central to selecting working wires?

  1. Stiffness Correct answer.
  2. Corrosion resistance
  3. Toughness
  4. Ductility

Explanation

Stiffness, or the load-deflection ratio, determines how much force a wire delivers at a given activation. Low-stiffness wires deliver light continuous forces, while high-stiffness wires are used for stabilization.

Question 7Orthodontics and Dentofacial Orthopedics

Which bracket prescription incorporates both tip and torque values built into the appliance to reduce the need for third-order wire bends?

  1. Preadjusted (straight-wire) appliance Correct answer.
  2. Twin-wire appliance
  3. Begg appliance
  4. Standard edgewise appliance

Explanation

Preadjusted brackets have tip, torque, and in-out values machined into the slot so that a flat wire expresses the intended tooth position. This reduces the number of first-, second-, and third-order bends needed.

Question 8Orthodontics and Dentofacial Orthopedics

Which anchorage situation provides the greatest resistance to unwanted tooth movement during retraction of anterior teeth?

  1. Moderate anchorage using posterior teeth on one side
  2. Simple anchorage using a single molar
  3. Reciprocal anchorage dividing movement equally between two units
  4. Maximum anchorage using the entire posterior segment plus extraoral or skeletal support Correct answer.

Explanation

Maximum anchorage recruits as many resistance units as possible, including the full posterior dentition and often extraoral or temporary skeletal anchorage, to minimize loss of posterior position. Greater resistance-unit support means less unwanted mesial drift of the anchor teeth.

Question 9Orthodontics and Dentofacial Orthopedics

A 9-year-old presents with a unilateral posterior crossbite and a functional shift on closure. What is the most appropriate early intervention?

  1. Observation until all permanent teeth erupt
  2. Extraction of the primary canine
  3. Maxillary expansion to correct the transverse discrepancy Correct answer.
  4. Placement of a fixed retainer

Explanation

A functional crossbite with a mandibular shift indicates a narrow maxilla that should be expanded early to remove the interference and allow normal growth. Delaying treatment can lead to asymmetric growth and skeletal adaptation.

Question 10Orthodontics and Dentofacial Orthopedics

Which appliance is most commonly used for orthopedic protraction of the maxilla in a growing patient with a skeletal Class III pattern due to maxillary deficiency?

  1. Face mask with palatal expansion Correct answer.
  2. Cervical headgear
  3. Reverse-pull chin cup alone
  4. Functional regulator

Explanation

A face mask delivers anteriorly directed orthopedic force to the maxilla and is typically combined with palatal expansion to loosen the circummaxillary sutures. This is indicated for maxillary deficiency in a growing Class III patient.

Question 11Orthodontics and Dentofacial Orthopedics

Which functional appliance principle is used to restrain mandibular growth in a growing patient with a skeletal Class III pattern?

  1. Activator therapy
  2. Chin cup therapy Correct answer.
  3. Twin block therapy
  4. Bionator therapy

Explanation

A chin cup applies posteriorly and superiorly directed force to the chin to restrain or redirect mandibular growth in selected growing Class III patients. Activators, twin blocks, and bionators are used to advance the mandible in Class II treatment.

Question 12Orthodontics and Dentofacial Orthopedics

Which of the following is a recognized advantage of clear aligner therapy compared with fixed appliances?

  1. Improved oral hygiene and esthetics Correct answer.
  2. Superior control of severe rotations
  3. Better three-dimensional root torque control
  4. Greater efficiency for complex extraction cases

Explanation

Removable aligners allow normal brushing and flossing and are less visible, improving hygiene and esthetics. Fixed appliances generally offer more predictable control of severe rotations and complex torque.

Question 13Orthodontics and Dentofacial Orthopedics

Which retention protocol is most appropriate after completion of active orthodontic treatment to reduce relapse?

  1. Full-time fixed or removable retention initially, with a gradual transition to part-time wear Correct answer.
  2. No retention if the occlusion is ideal
  3. Retention limited to the mandibular arch
  4. Retention only for one week

Explanation

Periodontal and gingival fibers reorganize slowly, so full-time retention is used initially and then tapered. Long-term or lifelong retention is often advised, especially for the lower incisors.

Question 14Orthodontics and Dentofacial Orthopedics

Which factor most strongly predicts root resorption during fixed appliance therapy?

  1. Patient age under 10 years
  2. Use of light continuous forces
  3. Use of a bonded retainer
  4. Prolonged treatment duration with heavy continuous forces Correct answer.

Explanation

Root resorption risk increases with long treatment duration and heavy or continuous force application, particularly with intrusion and torque. Light continuous forces and efficient mechanics reduce the risk.

Question 15Orthodontics and Dentofacial Orthopedics

A patient reports pain and blanching of a tooth shortly after elastomeric separation. What is the most likely cause?

  1. Allergic reaction to the separator
  2. Normal inflammatory response requiring no action
  3. Fracture of the alveolar bone
  4. Excessive separation force causing ischemia of the periodontal ligament Correct answer.

Explanation

Separators that are too thick or forcefully placed can compress the periodontal ligament enough to cause ischemia and discomfort. Reducing the force or using a thinner separator resolves the problem.

Question 16Orthodontics and Dentofacial Orthopedics

Which cephalometric measure best describes the anteroposterior position of the mandible relative to the cranial base?

  1. Facial axis
  2. ANB angle
  3. SNB angle Correct answer.
  4. SNA angle

Explanation

The SNB angle relates the mandible to the sella-nasion line and reflects mandibular anteroposterior position. SNA reflects maxillary position, and ANB reflects the difference between the two.

Question 17Orthodontics and Dentofacial Orthopedics

Which space analysis method compares the available arch perimeter with the sum of mesiodistal tooth widths to estimate crowding?

  1. Moyers mixed dentition analysis Correct answer.
  2. Pont's index
  3. Bolton analysis
  4. Carey's analysis

Explanation

Moyers analysis uses the widths of erupted mandibular incisors to predict the sizes of unerupted canines and premolars, allowing comparison with arch perimeter. Bolton analysis, by contrast, compares tooth-size ratios between arches.

Question 18Orthodontics and Dentofacial Orthopedics

Which condition is a contraindication to orthodontic tooth movement?

  1. History of orthodontic treatment
  2. Active untreated periodontal disease with bone loss Correct answer.
  3. Controlled asthma
  4. Mild dental fluorosis

Explanation

Active periodontal disease with unresolved inflammation and bone loss must be treated before orthodontic forces are applied, since forces can worsen attachment loss. Controlled medical conditions and prior treatment are not contraindications.

Question 19Orthodontics and Dentofacial Orthopedics

Which force system is used to correct a rotated tooth most efficiently?

  1. A continuous intrusive force
  2. A distal tipping force
  3. A single-point force directed toward the rotation
  4. A couple producing pure rotation Correct answer.

Explanation

A couple, consisting of two equal and opposite forces applied at a distance, produces a pure moment that rotates the tooth around its long axis. A single force would produce translation or tipping rather than controlled rotation.

Question 20Orthodontics and Dentofacial Orthopedics

Which type of tooth movement requires the greatest amount of force per unit area of root surface?

  1. Extrusion
  2. Intrusion Correct answer.
  3. Tipping
  4. Rotation

Explanation

Intrusion concentrates force over a small apical root area, so lighter forces are needed to avoid ischemia and root resorption. Extrusion requires the least force because it tension-loads the periodontal fibers.

Question 21Orthodontics and Dentofacial Orthopedics

Which skeletal pattern is most commonly associated with an anterior open bite tendency?

  1. Normal mandibular plane angle with Class I occlusion
  2. Increased mandibular plane angle with hyperdivergent growth Correct answer.
  3. Decreased mandibular plane angle with hypodivergent growth
  4. Reduced lower facial height

Explanation

A steep mandibular plane with hyperdivergent growth is associated with increased lower facial height and an anterior open bite tendency. Hypodivergent patterns are more often associated with deep bites.

Question 22Orthodontics and Dentofacial Orthopedics

Which habit is most strongly associated with anterior open bite and maxillary constriction in a child?

  1. Nail biting
  2. Prolonged digit sucking Correct answer.
  3. Tongue thrust only during swallowing
  4. Mouth breathing from nasal obstruction

Explanation

Prolonged digit sucking exerts pressure that proclines maxillary incisors, restricts maxillary transverse growth, and contributes to anterior open bite. Habit cessation or appliance therapy is often needed.

Question 23Orthodontics and Dentofacial Orthopedics

Which imaging modality provides three-dimensional assessment of impacted canines and root position without superimposition?

  1. Cone-beam computed tomography Correct answer.
  2. Panoramic radiograph
  3. Periapical radiograph
  4. Lateral cephalometric radiograph

Explanation

Cone-beam computed tomography provides three-dimensional data that localize impacted teeth and roots without the superimposition seen on two-dimensional images. It is used when precise spatial information is needed for treatment planning.

Question 24Orthodontics and Dentofacial Orthopedics

A patient has a Class II molar relationship with a deep overbite and a low mandibular plane angle. Which treatment approach is most appropriate?

  1. Intrusion of anterior teeth with mechanics that control the vertical dimension Correct answer.
  2. Bite opening with posterior bite blocks alone
  3. Extraction of maxillary incisors
  4. Extrusion of posterior teeth to increase the vertical dimension

Explanation

In a hypodivergent deep bite case, the vertical dimension is already reduced, so mechanics should intrude anterior teeth or control eruption rather than extrude posterior teeth. Extruding posteriors would worsen the deep bite tendency and facial profile.

Question 25Orthodontics and Dentofacial Orthopedics

Which retention device is most appropriate for maintaining the transverse dimension after rapid maxillary expansion?

  1. A bite plate
  2. A removable or fixed palatal retainer Correct answer.
  3. A cervical headgear
  4. A lower lingual holding arch

Explanation

After rapid maxillary expansion, the expanded transverse dimension must be retained while sutures and bone reorganize. A palatal retainer, removable or fixed, holds the width during this period.

Question 26Orthodontics and Dentofacial Orthopedics

Which type of malocclusion is characterized by the lower first molar being positioned mesial to the upper first molar by at least one half cusp width?

  1. Class IV
  2. Class I
  3. Class II
  4. Class III Correct answer.

Explanation

Angle's classification defines Class III as the lower first molar being mesial to the upper first molar by at least one half cusp width. Class I has the mesiobuccal cusp of the upper first molar in the buccal groove of the lower first molar, and Class II has the lower molar distal to that position. Class IV is not part of Angle's classification.

Question 27Orthodontics and Dentofacial Orthopedics

Which cephalometric angle is formed by the intersection of the Sella-Nasion line and the Nasion-A point line and is used to assess the anteroposterior position of the maxilla?

  1. ANB angle
  2. SN-MP angle
  3. SNB angle
  4. SNA angle Correct answer.

Explanation

The SNA angle is formed by the Sella-Nasion line and the Nasion-A point line and indicates the anteroposterior position of the maxilla relative to the cranial base. The SNB angle uses B point to assess the mandible, and the ANB angle is the difference between SNA and SNB. The SN-MP angle relates the mandibular plane to the cranial base.

Question 28Orthodontics and Dentofacial Orthopedics

Which stage of tooth development is characterized by the formation of the enamel organ, dental papilla, and dental follicle?

  1. Bud stage
  2. Root formation
  3. Bell stage
  4. Cap stage Correct answer.

Explanation

During the cap stage, the enamel organ invaginates to form a cap shape, and the dental papilla and dental follicle become distinct. The bud stage is an earlier, simpler epithelial thickening. The bell stage involves further differentiation and histodifferentiation, and root formation occurs after crown completion.

Question 29Orthodontics and Dentofacial Orthopedics

Which local factor is most likely to cause external root resorption during orthodontic treatment?

  1. Intermittent light forces
  2. Use of nickel-titanium wires
  3. Heavy continuous intrusive forces Correct answer.
  4. Rapid palatal expansion

Explanation

Heavy continuous intrusive forces concentrate stress at the root apex and can lead to external root resorption. Light intermittent forces are less likely to cause resorption. Nickel-titanium wires are favored for delivering light continuous forces, and rapid palatal expansion primarily affects the midpalatal suture and transverse dimension.

Question 30Orthodontics and Dentofacial Orthopedics

Which type of anchorage is provided when the resistance units include teeth in both the anterior and posterior segments of the same arch?

  1. Simple anchorage
  2. Reciprocal anchorage
  3. Stationary anchorage
  4. Compound anchorage Correct answer.

Explanation

Compound anchorage uses multiple teeth in the same arch, often including both anterior and posterior teeth, to increase resistance. Simple anchorage involves a single tooth, stationary anchorage uses teeth with their axes inclined to resist movement, and reciprocal anchorage uses equal and opposite forces between two units.

Question 31Orthodontics and Dentofacial Orthopedics

Which appliance is a removable functional appliance that postures the mandible forward to treat Class II malocclusion?

  1. Transpalatal arch
  2. Quad helix
  3. Twin-block appliance Correct answer.
  4. Lip bumper

Explanation

The Twin-block appliance is a removable functional appliance that uses bite blocks to posture the mandible forward and is used in growing patients with Class II malocclusion. A transpalatal arch and quad helix are fixed appliances for transverse correction, and a lip bumper is used to reduce lip pressure on the lower incisors.

Question 32Orthodontics and Dentofacial Orthopedics

Which index is commonly used to assess orthodontic treatment need based on the severity of malocclusion?

  1. Plaque Index
  2. Index of Orthodontic Treatment Need (IOTN) Correct answer.
  3. Gingival Index
  4. Decayed, Missing, Filled Teeth (DMFT) index

Explanation

The Index of Orthodontic Treatment Need (IOTN) is a validated tool that combines a dental health component and an aesthetic component to determine the need for orthodontic treatment. The DMFT index measures caries experience, and the Gingival and Plaque indices assess periodontal health and oral hygiene, respectively.

Question 33Orthodontics and Dentofacial Orthopedics

Which cephalometric landmark is located at the deepest point of the curvature of the anterior maxilla?

  1. Pogonion
  2. Menton
  3. Point B
  4. Point A Correct answer.

Explanation

Point A (subspinale) is the deepest point on the anterior contour of the maxilla and is used in the SNA angle. Point B is on the mandible, pogonion is the most anterior point on the chin, and menton is the lowest point on the mandibular symphysis.

Question 34Orthodontics and Dentofacial Orthopedics

A patient has a Class I skeletal pattern with a severe mandibular anterior crowding of 8 mm. Which treatment approach is most appropriate?

  1. Extraction of mandibular first premolars Correct answer.
  2. Distalization of mandibular molars
  3. Use of a functional appliance
  4. Expansion of the mandibular arch with a lip bumper

Explanation

Severe mandibular crowding in a patient with a Class I skeletal pattern often requires extraction of premolars to create space for alignment. A lip bumper may provide mild space but is insufficient for 8 mm of crowding. Mandibular molar distalization is limited by the lingual cortex, and functional appliances are used for growth modification in Class II patients.

Question 35Orthodontics and Dentofacial Orthopedics

A 12-year-old patient has a Class II division 1 malocclusion with an overjet of 10 mm and a normal mandibular plane angle. Which treatment modality is most appropriate after initial alignment?

  1. Extraction of maxillary first premolars Correct answer.
  2. Headgear to the maxilla
  3. Rapid maxillary expansion
  4. Functional appliance therapy

Explanation

In a growing patient with a large overjet and normal vertical pattern, extraction of maxillary first premolars can provide space to retract the maxillary incisors and reduce overjet. Functional appliances are better suited for mandibular advancement in Class II patients with mandibular deficiency. Rapid maxillary expansion addresses transverse deficiency, and headgear is less commonly used today for this purpose.

Question 36Orthodontics and Dentofacial Orthopedics

A patient presents with a unilateral posterior crossbite and a centric relation to centric occlusion shift. Which treatment is most appropriate?

  1. Extraction of the crossbite tooth
  2. Observation only
  3. Maxillary expansion Correct answer.
  4. Mandibular expansion

Explanation

A unilateral posterior crossbite with a functional shift indicates a transverse maxillary deficiency, and maxillary expansion is the treatment of choice. Mandibular expansion is rarely indicated. Extraction would not address the underlying skeletal discrepancy, and observation would allow the shift to persist.

Question 37Orthodontics and Dentofacial Orthopedics

Which force magnitude is generally recommended for intrusion of anterior teeth?

  1. 10-20 g per tooth Correct answer.
  2. 200-300 g per tooth
  3. 100-200 g per tooth
  4. 50-100 g per tooth

Explanation

Intrusion requires light continuous forces, typically in the range of 10-20 g per tooth, to minimize root resorption and patient discomfort. Higher forces are used for extrusion or translation but increase the risk of tissue damage. Forces above 50 g per tooth are generally excessive for intrusion.

Question 38Orthodontics and Dentofacial Orthopedics

Which retention strategy is most appropriate for a patient with a history of severe mandibular crowding after orthodontic treatment?

  1. Fixed lingual retainer Correct answer.
  2. Positioner
  3. Removable Hawley retainer
  4. No retention

Explanation

A fixed lingual retainer is effective in maintaining alignment of the mandibular anterior teeth, which are prone to relapse after correction of severe crowding. A removable Hawley retainer relies on patient compliance and may not provide sufficient resistance to relapse. No retention would likely lead to recurrence, and a positioner is less commonly used for long-term retention.

Question 39Orthodontics and Dentofacial Orthopedics

Which skeletal discrepancy is indicated by an ANB angle of 8 degrees?

  1. Skeletal Class II Correct answer.
  2. Skeletal Class III
  3. Skeletal Class I
  4. Skeletal Class IV

Explanation

An ANB angle greater than 4 degrees typically indicates a skeletal Class II relationship due to a prognathic maxilla, retrognathic mandible, or both. A normal ANB is about 2-4 degrees (Class I), and a negative ANB suggests Class III. Class IV is not a recognized skeletal classification.

Question 40Orthodontics and Dentofacial Orthopedics

Which factor is most important in determining the prognosis of an impacted maxillary canine?

  1. Vertical position of the canine tip Correct answer.
  2. Patient's age
  3. Angle of the canine to the midline
  4. Presence of the primary canine

Explanation

The vertical position of the impacted canine tip relative to the adjacent incisor root is a strong predictor of treatment difficulty and prognosis. A more apical position often requires longer treatment and may have a worse prognosis. Patient age, presence of the primary canine, and angulation also matter but are less predictive than vertical position.

Question 41Orthodontics and Dentofacial Orthopedics

Which appliance is used for slow maxillary expansion in a growing patient with a constricted maxilla?

  1. Facemask
  2. Rapid palatal expander
  3. Quad helix Correct answer.
  4. Herbst appliance

Explanation

The quad helix is a fixed appliance that delivers slow, continuous expansion forces to the maxilla and is often used in growing patients. A rapid palatal expander delivers heavy forces for rapid expansion. A facemask is used for protraction of the maxilla, and a Herbst appliance is a fixed functional appliance for Class II correction.

Question 42Orthodontics and Dentofacial Orthopedics

Which wire sequence is most appropriate for initial leveling and alignment in fixed appliance therapy?

  1. Nickel-titanium wires of increasing diameter Correct answer.
  2. Beta-titanium wires of constant diameter
  3. Cobalt-chromium wires of large diameter
  4. Stainless steel wires of decreasing diameter

Explanation

Initial leveling and alignment typically use nickel-titanium wires because of their low stiffness and ability to deliver light continuous forces. The diameter is gradually increased to fill the bracket slot. Stainless steel wires are stiffer and used later for space closure, beta-titanium for auxiliary functions, and cobalt-chromium for specific applications.

Question 43Orthodontics and Dentofacial Orthopedics

Which type of tooth movement is most efficiently achieved with a force applied through the center of resistance?

  1. Translation Correct answer.
  2. Rotation
  3. Intrusion
  4. Extrusion

Explanation

Translation, or bodily movement, occurs when the line of action of the force passes through the center of resistance, resulting in pure translation without rotation. Rotation requires a couple, and intrusion and extrusion require forces along the long axis but are not pure translation.

Question 44Orthodontics and Dentofacial Orthopedics

Which cephalometric measurement is used to assess the vertical relationship between the maxilla and mandible?

  1. SNB angle
  2. Mandibular plane angle Correct answer.
  3. SNA angle
  4. ANB angle

Explanation

The mandibular plane angle (e.g., SN-MP or FMA) reflects the vertical relationship of the mandible to the cranial base and is used to assess the patient's vertical skeletal pattern. SNA, SNB, and ANB assess anteroposterior relationships.

Question 45Orthodontics and Dentofacial Orthopedics

Which local etiologic factor is most commonly associated with anterior open bite?

  1. Prolonged thumb sucking Correct answer.
  2. Premature loss of primary molars
  3. Enlarged adenoids
  4. Mouth breathing

Explanation

Prolonged thumb sucking exerts pressure on the maxillary incisors and can lead to anterior open bite and maxillary constriction. Mouth breathing and enlarged adenoids are associated with open bite but are less direct local factors. Premature loss of primary molars primarily affects space maintenance.

Question 46Orthodontics and Dentofacial Orthopedics

Which radiograph is the gold standard for assessing root parallelism and bone levels during orthodontic treatment?

  1. Periapical radiograph Correct answer.
  2. Panoramic radiograph
  3. Cephalometric radiograph
  4. Cone beam computed tomography

Explanation

Periapical radiographs provide high-resolution images of individual teeth and surrounding bone, making them ideal for assessing root parallelism and bone levels. Panoramic and cephalometric radiographs offer broader views but with less detail, and CBCT provides 3D imaging but is not routinely used for this purpose due to higher radiation dose.

Question 47Orthodontics and Dentofacial Orthopedics

A patient with a Class III malocclusion and maxillary deficiency is treated with a facemask. What is the primary orthopedic effect of this appliance?

  1. Retraction of the mandible
  2. Intrusion of maxillary incisors
  3. Expansion of the mandibular arch
  4. Protraction of the maxilla Correct answer.

Explanation

The facemask applies anteriorly directed force to the maxilla, promoting orthopedic protraction and forward displacement of the maxilla in growing patients with Class III malocclusion. It does not directly retract the mandible, intrude incisors, or expand the mandibular arch.

Question 48Orthodontics and Dentofacial Orthopedics

Which retention protocol is recommended after rapid maxillary expansion to maintain transverse correction?

  1. Extraction of premolars
  2. Nothing, as relapse is minimal
  3. Fixed transpalatal arch or removable plate Correct answer.
  4. Immediate fixed retainers on all teeth

Explanation

After rapid maxillary expansion, the transverse dimension tends to relapse, so retention with a fixed transpalatal arch or a removable plate is recommended to maintain the expansion. Doing nothing would likely lead to relapse. Fixed retainers on all teeth are not necessary, and extractions do not address transverse retention.

Question 49Orthodontics and Dentofacial Orthopedics

Which factor is most likely to increase the risk of enamel demineralization during fixed appliance therapy?

  1. Consumption of a low-sugar diet
  2. Regular professional cleanings
  3. Poor oral hygiene Correct answer.
  4. Use of fluoride toothpaste

Explanation

Poor oral hygiene leads to plaque accumulation around brackets and increases the risk of enamel demineralization (white spot lesions). Fluoride toothpaste, professional cleanings, and a low-sugar diet are preventive measures that reduce the risk.

Question 50Orthodontics and Dentofacial Orthopedics

Which type of malocclusion is most commonly associated with a deep bite?

  1. Class I with anterior open bite
  2. Class II division 2 Correct answer.
  3. Class III
  4. Class II division 1

Explanation

Class II division 2 malocclusion is characterized by retroclined maxillary central incisors, a deep overbite, and often a low mandibular plane angle. Class III and Class I with anterior open bite are not typically associated with deep bite, and Class II division 1 often has increased overjet rather than deep bite.