ABO ABO Retention and Stability 2 — Questions and Answers
Question 1: Bonded retainers should be checked at recall visits primarily for:
- Changes in wire gauge
- Bond failures, wire distortion, and signs of plaque accumulation (Correct answer)
- Changes in bracket color
- Evidence of root resorption
Correct answer: Bond failures, wire distortion, and signs of plaque accumulation
Bonded retainer recall includes checking bond integrity, wire distortion, and periodontal health since fixed wires can accumulate plaque.
Question 2: Essix (vacuum-formed) retainers are contraindicated in patients who:
- Have all permanent teeth erupted
- Exhibit bruxism or severe parafunction (Correct answer)
- Are in the early permanent dentition
- Have had premolar extractions
Correct answer: Exhibit bruxism or severe parafunction
Patients with bruxism can rapidly wear through or fracture vacuum-formed retainers, reducing their effectiveness and potentially damaging dentition.
Question 3: Long-term stability of corrected Class III malocclusion treated with growth modification is LEAST favorable in patients with:
- Mild skeletal discrepancy
- Horizontal mandibular growth pattern
- Vertical mandibular growth pattern and strong Class III genetics (Correct answer)
- Early treatment start
Correct answer: Vertical mandibular growth pattern and strong Class III genetics
A vertical growth pattern combined with strong Class III genetic tendency produces the highest risk of relapse after orthopedic correction.
Question 4: The primary purpose of a positioner appliance at the end of fixed treatment is to:
- Initiate space closure
- Seat and refine the occlusion while providing initial retention (Correct answer)
- Expand the dental arches
- Correct anterior open bite
Correct answer: Seat and refine the occlusion while providing initial retention
Positioners use a flexible rubber or silicone tray to detail and seat the occlusion while simultaneously acting as a short-term retainer.
Question 5: According to the ABO grading system, which OGS (Objective Grading System) criterion evaluates the axial inclination of posterior teeth?
- Marginal ridges
- Buccolingual inclination
- Overjet
- Root angulation (Correct answer)
Correct answer: Root angulation
The ABO OGS root angulation criterion evaluates whether roots are properly parallel and properly angulated on the final panoramic radiograph.
Question 6: Retention protocol for a patient treated for a severe anterior open bite should ideally include:
- No retainer since open bites are stable
- Short-term Hawley retainer only
- Long-term or indefinite retention, often with a fixed retainer (Correct answer)
- Removal of retainer after 6 months
Correct answer: Long-term or indefinite retention, often with a fixed retainer
Anterior open bites are among the least stable corrections in orthodontics, requiring long-term or permanent retention to prevent relapse.
ABO ABO Retention and Stability 2
Bonded retainers should be checked at recall visits primarily for: