Orthodontics Prometric exam questions with answers

1. Question 1Biology of Tooth Movement and Biomechanicsmedium

   Which type of tooth movement requires the lightest force because the force is concentrated over a small area at the root apex?

   1. AIntrusion
   2. BBodily movement
   3. CRoot uprighting
   4. DExtrusion
   Show answer and explanation▾

   Answer: A. Intrusion

   In intrusion the force is concentrated at the apex, so very light forces of about 10 to 20 g per tooth are recommended to limit root resorption. Bodily movement spreads force over the whole root surface and needs more.

2. Question 2Interceptive Orthodonticshard

   A 5-year-old has a lower primary second molar extracted because of an abscess. The first permanent molar is still unerupted. Which space maintainer is indicated?

   1. ABand and loop on the first permanent molar
   2. BDistal shoe appliance
   3. CLower lingual holding arch
   4. DRemovable partial denture
   Show answer and explanation▾

   Answer: B. Distal shoe appliance

   Before the first permanent molar erupts, a distal shoe guides it into position and prevents mesial drift. A band and loop or lingual arch needs an erupted molar for anchorage.

3. Question 3Craniofacial Growth and Developmentmedium

   During growth the mandibular body lengthens to make space for erupting permanent molars. Which remodelling pattern of the ramus achieves this?

   1. ADeposition anteriorly and resorption posteriorly
   2. BDeposition posteriorly and resorption anteriorly
   3. CInterstitial growth within the mandibular body
   4. DSutural growth at the mandibular symphysis
   Show answer and explanation▾

   Answer: B. Deposition posteriorly and resorption anteriorly

   The ramus drifts posteriorly by bone deposition on its posterior border and resorption on its anterior border, converting former ramus into body. The symphysis fuses in the first year of life, so it does not contribute later.

4. Question 4Craniofacial Growth and Developmentmedium

   A clinician plans to preserve leeway space with a lower lingual arch in a child with mild crowding. Which statement about leeway space is correct?

   1. AIt is larger in the maxillary than mandibular arch
   2. BIt is larger in the mandibular than maxillary arch
   3. CIt is equal in both arches
   4. DIt results from primary incisor exfoliation
   Show answer and explanation▾

   Answer: B. It is larger in the mandibular than maxillary arch

   Leeway space is the difference in size between the primary canine and molars and their successors, and it is greater in the mandible because the lower primary second molar is much larger than the second premolar. A lingual arch can preserve it to relieve mild crowding.

5. Question 5Orthodontic Diagnosis and Cephalometricseasy

   In the permanent mandibular arch, the sum of mesiodistal widths from first molar to first molar is 74 mm and the measured arch perimeter is 68 mm. What is the space discrepancy?

   1. A12 mm of crowding
   2. B6 mm of spacing
   3. C3 mm of crowding
   4. D6 mm of crowding
   Show answer and explanation▾

   Answer: D. 6 mm of crowding

   Space required (74 mm) minus space available (68 mm) gives 6 mm of crowding. Spacing would occur only if available space exceeded the required tooth widths.

6. Question 6Interceptive Orthodonticsmedium

   A 9-year-old has a unilateral posterior crossbite with a lateral mandibular shift on closure from a symmetric centric relation. What is the recommended management?

   1. AMonitor until the permanent dentition
   2. BMaxillary expansion to eliminate the shift
   3. CMandibular arch expansion only
   4. DGrind the lower primary molars only
   Show answer and explanation▾

   Answer: B. Maxillary expansion to eliminate the shift

   A crossbite with displacement is usually due to a bilaterally narrow maxilla, and early expansion removes the shift and may prevent asymmetric development. Leaving it may allow adaptive mandibular asymmetry.

7. Question 7Orthognathic Surgery, Cleft and Interdisciplinary Carehard

   A 15-year-old boy with severe mandibular prognathism asks for surgery now. What is the best approach to timing?

   1. AWait until growth ends, confirmed by serial cephs
   2. BOperate now and repeat surgery if needed
   3. COperate once the second molars erupt
   4. DOperate at the next pubertal growth spurt
   Show answer and explanation▾

   Answer: A. Wait until growth ends, confirmed by serial cephs

   Mandibular growth continues late in males with Class III patterns, so surgery is deferred until growth has ceased, ideally confirmed by superimposed cephalograms taken months apart. Operating early risks relapse from continued growth.

8. Question 8Retention, Relapse and Iatrogenic Riskseasy

   A 14-year-old about to start fixed appliances has moderate plaque levels. Which measure most reduces the risk of white spot lesions?

   1. ABonding with non-fluoride composite
   2. BStarting a chlorhexidine rinse alone
   3. CFluoride toothpaste plus extra fluoride
   4. DRemoving appliances every 6 months
   Show answer and explanation▾

   Answer: C. Fluoride toothpaste plus extra fluoride

   Good oral hygiene with fluoride toothpaste, supplemented by fluoride varnish or daily fluoride mouthrinse, is the best supported way to reduce demineralisation. Chlorhexidine alone has weaker evidence.

9. Question 9Malocclusion Classification and Treatment Planningmedium

   Parents ask about early treatment for their 8-year-old with a 9 mm overjet and incompetent lips. According to systematic review evidence, what is the main benefit of early treatment compared with treatment in adolescence?

   1. AReduced incidence of incisor trauma
   2. BGreater long-term skeletal change
   3. CShorter overall treatment time
   4. DBetter final occlusion scores
   Show answer and explanation▾

   Answer: A. Reduced incidence of incisor trauma

   Cochrane evidence shows early functional treatment for prominent upper incisors reduces new incisal trauma but offers no major advantage in skeletal or final occlusal outcomes. Overall treatment time is usually longer with two phases.

10. Question 10Orthodontic Appliances and Materialsmedium

    During bracket bonding, a freshly etched and dried enamel surface is contaminated with saliva before primer is applied. What is the correct action?

    1. AWipe with cotton roll and bond
    2. BDry with air and bond immediately
    3. CApply more primer to absorb the saliva
    4. DRinse, dry and re-etch for a short time
    Show answer and explanation▾

    Answer: D. Rinse, dry and re-etch for a short time

    Saliva deposits a pellicle on the etched surface that reduces bond strength, so the area should be rinsed, dried and briefly re-etched. Drying alone does not remove the contaminating proteins.

11. Question 11Orthodontic Diagnosis and Cephalometricsmedium

    A 13-year-old has a palatally impacted maxillary canine, and plain radiographs suggest possible resorption of the adjacent lateral incisor root. What is the most appropriate imaging?

    1. ARepeat panoramic radiograph in 6 months
    2. BLarge field-of-view CBCT of the skull
    3. CLimited field-of-view CBCT
    4. DMedical CT of the maxilla
    Show answer and explanation▾

    Answer: C. Limited field-of-view CBCT

    When conventional radiographs cannot answer the question, a limited field-of-view CBCT is justified to localise the canine and assess root resorption at the lowest dose. Large-volume scans and medical CT give unnecessary radiation.

12. Question 12Orthognathic Surgery, Cleft and Interdisciplinary Caremedium

    A 19-year-old with a skeletal Class III pattern is planned for bimaxillary surgery. What is the main goal of pre-surgical orthodontics?

    1. AClose all spaces by retracting incisors
    2. BIncrease dental compensations
    3. CAchieve a normal overjet first
    4. DRemove dental compensations
    Show answer and explanation▾

    Answer: D. Remove dental compensations

    Pre-surgical orthodontics decompensates the incisors, usually retroclining the uppers and proclining the lowers, which increases the reverse overjet but allows full surgical correction. Achieving a normal overjet before surgery would limit the skeletal movement possible.

13. Question 13Orthognathic Surgery, Cleft and Interdisciplinary Caremedium

    A child with a repaired unilateral cleft lip and palate is due for secondary alveolar bone grafting. What is the usual timing?

    1. AAfter eruption of second permanent molars
    2. BAt the time of lip repair in infancy
    3. CAfter completion of facial growth
    4. DBefore canine eruption, about 8 to 11 years
    Show answer and explanation▾

    Answer: D. Before canine eruption, about 8 to 11 years

    Secondary alveolar bone grafting is ideally done before the permanent canine erupts, typically between 8 and 11 years, when the canine root is partly formed. This lets the canine erupt through the graft and maintain it.

14. Question 14Radiation Protection, Infection Control and Ethicsmedium

    A clinician proposes routine CBCT for all new orthodontic patients to improve records. What is the most appropriate response under radiation protection principles?

    1. AJustified as it gives 3D information
    2. BNot justified as a routine record
    3. CJustified if a thyroid collar is used
    4. DJustified for all patients over 18
    Show answer and explanation▾

    Answer: B. Not justified as a routine record

    Each exposure must be justified for the individual patient, and CBCT should not be used routinely for orthodontic diagnosis. It is reserved for cases where conventional radiographs cannot provide the needed information.

15. Question 15Retention, Relapse and Iatrogenic Risksmedium

    A severely rotated maxillary lateral incisor has been corrected. Which adjunct most reduces the tendency for the rotation to relapse?

    1. AInterproximal enamel reduction
    2. BSupracrestal fiberotomy
    3. CLabial frenectomy
    4. DGingival recontouring
    Show answer and explanation▾

    Answer: B. Supracrestal fiberotomy

    Stretched supracrestal gingival fibres remodel slowly and pull rotated teeth back, so fiberotomy reduces rotational relapse. Frenectomy and gingival recontouring do not address the stretched fibres.

Last reviewed September 2026. Questions are original and written to the published exam blueprint; they are not taken from any real paper.