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Reading the malocclusion · Orthodontics · INBDE Patient Cases

Diagnosis & Classification INBDE Patient Cases

By Dr. Isaac Sun, DDS

7 ADA INBDE-format patient cases on diagnosis & classification. Each case is a shared patient box (chief complaint, history, medications, allergies, exam) followed by linked multiple-choice questions with full distractor explanations. Practice the way the real exam is structured.

7 patient cases35 linked questionsADA INBDE formatFull distractor explanations

Seven ADA INBDE-format patient cases on orthodontic diagnosis and classification: Class II Division 1 with a large overjet and traumatic injury risk in a growing patient, Class II Division 2 with deep impinging overbite and bite-opening mechanics, Class III with anterior crossbite treated with a facemask in the growing patient and orthognathic surgery in the non-growing patient, posterior crossbite with a functional shift treated with rapid maxillary expansion, anterior open bite from a thumb-sucking habit with behavioral counseling and a habit appliance, reading a lateral cephalogram for skeletal Class II with a high-angle vertical pattern (and the high-pull headgear choice), and a complete records summary in mixed dentition. Topics include Angle's classification, dental vs skeletal class, overjet, overbite, crossbite, openbite, cephalometric ANB and FMA, the Bolton ratio, the IOTN, and the orthodontic diagnosis summary across three planes.

Case Coverage Map
What each case is testing
Class II Div 1 with a large overjet:
Reading Class II Div 1 (Class II molar + proclined upper centrals + large overjet), trauma risk, ANB for skeletal pattern, and using growth with a functional appliance.
Class II Div 2 with a deep bite:
Class II Div 2 reading (retroclined upper centrals + flared laterals + deep bite), palatal trauma, brachyfacial pattern, and bite-opening mechanics.
Class III with anterior crossbite:
Class III reading (mesial mandible + anterior crossbite + ANB < 0°), facemask in growing patients, and orthognathic surgery in non-growing severe Class III.
Posterior crossbite with a functional shift:
Bilateral constriction + unilateral crossbite from a functional shift, RPE in growing patients, asymmetric growth and TMD risk, and midpalatal suture timing.
Anterior open bite and a thumb-sucking habit:
Habit-driven open bite + narrow arch + proclined upper centrals, behavioral counseling and habit appliances, and the spontaneous-improvement window in young children.
Reading a lateral cephalogram:
ANB + FMA reading, high-angle skeletal Class II, and the high-pull vs cervical headgear distinction that follows from the vertical pattern.
Putting the records together:
Complete diagnosis across three planes plus the skeletal vs dental component, standard records (photos + pan + ceph + models), and the problem-list-driven plan.
Patient case: Class II Div 1 with a large overjet
0 of 5 answered, 0 correct
Patient
Male, 11 years old
Chief Complaint
Family concerned about prominent upper front teeth.
Background and/or Patient History
  • Mixed dentition with proclined upper centrals
  • Overjet measures 9 mm; deep overbite
  • Class II molar and canine on both sides; convex profile
Allergies
NKDA
Medications
  • None
Current Findings
  • Class II Div 1 with large overjet
  • Lip incompetence at rest
  • ANB 5°
  1. Question 1
    Easy
    The Angle classification is:
  2. Question 2
    Moderate
    The increased overjet raises the risk of:
  3. Question 3
    Moderate
    The ANB of 5° suggests a:
  4. Question 4
    Moderate
    Because the patient is still growing, an option that uses growth is:
  5. Question 5
    Easy
    The teaching point is that the diagnosis names the:

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Patient case: Class II Div 2 with a deep bite
0 of 5 answered, 0 correct
Patient
Female, 14 years old
Chief Complaint
Family concerned about a 'closed' bite and worn lower incisors.
Background and/or Patient History
  • Class II molar bilaterally
  • Retroclined upper centrals with flared upper laterals
  • Deep overbite with lower incisors impinging on palatal mucosa
Allergies
NKDA
Medications
  • None
Current Findings
  • Class II Div 2 with deep impinging overbite
  • Brachyfacial pattern (low FMA)
  1. Question 1
    Easy
    The Angle subclassification is:
  2. Question 2
    Moderate
    Deep bite with lower incisors impinging on the palate raises the risk of:
  3. Question 3
    Hard
    The brachyfacial pattern is typically associated with:
  4. Question 4
    Hard
    Initial mechanics for deep overbite include:
  5. Question 5
    Easy
    The teaching point is that Class II Div 2 differs from Div 1 in:

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Patient case: Class III with anterior crossbite
0 of 5 answered, 0 correct
Patient
Male, 9 years old
Chief Complaint
Family notes a 'bulldog' bite with lower teeth in front of upper teeth.
Background and/or Patient History
  • Concave facial profile
  • Lower incisors anterior to upper incisors at maximum intercuspation
  • Class III molar bilaterally
Allergies
NKDA
Medications
  • None
Current Findings
  • Skeletal Class III tendency with anterior crossbite
  • Growing patient
  1. Question 1
    Easy
    The Angle classification is:
  2. Question 2
    Moderate
    A typical cephalometric finding here is:
  3. Question 3
    Hard
    Because the patient is growing, an early option for skeletal Class III is:
  4. Question 4
    Moderate
    After growth completes, severe skeletal Class III is often treated with:
  5. Question 5
    Easy
    The teaching point of this case is:

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Patient case: Posterior crossbite with a functional shift
0 of 5 answered, 0 correct
Patient
Female, 8 years old
Chief Complaint
Asymmetric smile with the mandible drifting to one side on closure.
Background and/or Patient History
  • On initial contact, midlines align; on closure to maximum intercuspation, mandible shifts to the right
  • Unilateral right posterior crossbite
  • Narrow maxillary arch
Allergies
NKDA
Medications
  • None
Current Findings
  • Bilateral maxillary constriction producing unilateral functional crossbite
  • Growing patient
  1. Question 1
    Hard
    The clinical picture (initial bilateral contact, shift to one side, unilateral crossbite) most likely reflects:
  2. Question 2
    Moderate
    Treatment in the growing patient is typically:
  3. Question 3
    Moderate
    Untreated, this kind of crossbite can lead over time to:
  4. Question 4
    Moderate
    The midpalatal suture closes around:
  5. Question 5
    Easy
    The teaching point is that a posterior crossbite with a functional shift:

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Patient case: Anterior open bite and a thumb-sucking habit
0 of 5 answered, 0 correct
Patient
Female, 7 years old
Chief Complaint
Anterior open bite noted on examination; ongoing thumb-sucking habit.
Background and/or Patient History
  • Persistent thumb-sucking through the day and at night
  • Anterior open bite with proclined upper centrals
  • Narrow upper arch and high-arched palate
Allergies
NKDA
Medications
  • None
Current Findings
  • Habit-related anterior open bite
  • Growing patient
  1. Question 1
    Easy
    The most likely primary contributor to the open bite is:
  2. Question 2
    Moderate
    Beyond open bite, persistent thumb sucking also tends to produce:
  3. Question 3
    Moderate
    First-line management in a young child is:
  4. Question 4
    Moderate
    If the habit is stopped early, the open bite often:
  5. Question 5
    Hard
    If the open bite persists into the permanent dentition and reflects a high-angle skeletal pattern, treatment may include:

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Patient case: Reading a lateral cephalogram
0 of 5 answered, 0 correct
Patient
Male, 13 years old
Chief Complaint
Routine orthodontic records with a lateral cephalogram and panoramic film.
Background and/or Patient History
  • Comprehensive orthodontic workup
  • Lateral cephalogram traced; SNA 84°, SNB 78°, ANB 6°, FMA 32°
  • Mixed-to-permanent dentition
Allergies
NKDA
Medications
  • None
Current Findings
  • Cephalometric values consistent with Class II skeletal, high-angle vertical pattern
  1. Question 1
    Moderate
    An ANB of 6° suggests:
  2. Question 2
    Moderate
    An FMA of 32° suggests:
  3. Question 3
    Hard
    Combining ANB 6° with FMA 32° suggests:
  4. Question 4
    Hard
    Treatment approach in this growing patient might use:
  5. Question 5
    Easy
    The teaching point is that the cephalogram:

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Patient case: Putting the records together
0 of 5 answered, 0 correct
Patient
Female, 10 years old
Chief Complaint
Family asks for an orthodontic evaluation and 'what the plan is.'
Background and/or Patient History
  • Mixed dentition; Class II molar bilaterally; canine Class II
  • Overjet 8 mm; overbite 60 percent
  • ANB 5°; FMA 24°
  • Records: photographs, panoramic, lateral cephalogram, study models
Allergies
NKDA
Medications
  • None
Current Findings
  • Class II Div 1 dental, Class II skeletal, average vertical pattern
  • Diagnosis summary opportunity
  1. Question 1
    Easy
    A complete diagnosis names the malocclusion in:
  2. Question 2
    Easy
    For this patient, the A-P diagnosis is:
  3. Question 3
    Moderate
    The vertical pattern in this patient is:
  4. Question 4
    Easy
    Records that should be obtained at this stage include:
  5. Question 5
    Easy
    The teaching point of this case is that:

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