ABO (Reading) 2 — Questions and Answers
Question 1: In the ABO Written Examination, which reference domain covers the biological basis of tooth movement including periodontal ligament response to force?
- Biomechanics and biology (Correct answer)
- Facial esthetics
- Practice management
- Radiographic interpretation
Correct answer: Biomechanics and biology
Tooth movement biology and periodontal ligament force response fall under the biomechanics and biology domain.
Question 2: According to standard orthodontic literature, what is the optimal light continuous force range generally cited for bodily tooth movement?
- Under 5 grams
- 50-100 grams (Correct answer)
- 500-800 grams
- Over 1000 grams
Correct answer: 50-100 grams
Light continuous forces around 50-100 grams are commonly cited as optimal for efficient bodily movement.
Question 3: The ABO Case Report Exam evaluates finished cases partly through which standardized scoring instrument?
- PAR index only
- Discrepancy Index and Cast-Radiograph Evaluation (Correct answer)
- Bolton analysis alone
- Angle classification chart
Correct answer: Discrepancy Index and Cast-Radiograph Evaluation
ABO uses the Discrepancy Index for case complexity and the Cast-Radiograph Evaluation for finished-case quality.
Question 4: Which cephalometric angle is most directly used to assess the anteroposterior relationship between maxilla and mandible?
- ANB angle (Correct answer)
- SN-GoGn angle
- Interincisal angle
- Y-axis
Correct answer: ANB angle
The ANB angle expresses the sagittal relationship between the maxilla (A point) and mandible (B point).
Question 5: In reading periapical radiographs for orthodontic assessment, external apical root resorption appears as which finding?
- Widened periodontal space uniformly
- Blunted or shortened root apices (Correct answer)
- Increased root length
- Enamel pearls at the cementoenamel junction
Correct answer: Blunted or shortened root apices
External apical root resorption presents radiographically as blunting or shortening of the root apex.
Question 6: Per ABO clinical standards, an ideal overbite at case completion is generally described as which percentage of incisor overlap?
- 0% (edge to edge)
- 10-30% (Correct answer)
- 50-70%
- 100% (deep bite)
Correct answer: 10-30%
A normal, ideal overbite is roughly 10-30% vertical overlap of the mandibular incisors.
Question 7: Which growth prediction concept states that mandibular growth direction can be estimated from the cephalometric Y-axis?
- Mesh diagram analysis
- Growth axis interpretation (Correct answer)
- Steiner box analysis
- Frankfort mandibular plane inversion
Correct answer: Growth axis interpretation
The Y-axis (SGn to Frankfort) is read to interpret the direction and pattern of mandibular growth.
ABO (Reading) 2
In the ABO Written Examination, which reference domain covers the biological basis of tooth movement including periodontal ligament response to force?