ABO ABO Dentofacial Orthopedics 1 — Questions and Answers
Question 1: The rapid palatal expander (RPE) creates a midpalatal suture opening. At what age does this suture typically become interdigitated and difficult to expand non-surgically?
- 8–10 years
- 10–12 years
- 14–16 years
- After 16–17 years of age (Correct answer)
Correct answer: After 16–17 years of age
After approximately 16–17 years of age the midpalatal suture becomes heavily interdigitated, making non-surgical expansion increasingly difficult and unpredictable.
Question 2: A cervical-pull headgear applies force in which direction relative to the maxilla?
- Superiorly and posteriorly
- Inferiorly and posteriorly (Correct answer)
- Directly posteriorly only
- Anteriorly and superiorly
Correct answer: Inferiorly and posteriorly
Cervical-pull headgear pulls the maxilla inferiorly and posteriorly, which can increase lower facial height in growing patients.
Question 3: Which functional appliance is a one-piece, tooth-borne, mandibular advancement device that requires bilateral simultaneous engagement?
- Bionator
- Twin Block appliance (Correct answer)
- Activator
- Frankel appliance
Correct answer: Twin Block appliance
The Twin Block appliance consists of upper and lower acrylic blocks with inclined planes that interlock to advance the mandible when the mouth closes.
Question 4: Protraction facemask therapy is indicated for which skeletal problem?
- Skeletal Class II due to mandibular retrusion
- Skeletal Class III due to maxillary deficiency (Correct answer)
- Vertical excess of the maxilla
- Transverse maxillary deficiency
Correct answer: Skeletal Class III due to maxillary deficiency
Facemask (reverse-pull headgear) therapy applies forward traction to the maxilla to treat Class III malocclusion caused by maxillary undergrowth.
Question 5: Bone-anchored maxillary protraction uses mini-implants instead of tooth anchorage primarily to:
- Reduce treatment time
- Avoid dentoalveolar side effects like incisor proclination (Correct answer)
- Enable treatment in adults
- Decrease patient discomfort
Correct answer: Avoid dentoalveolar side effects like incisor proclination
Skeletal anchorage for facemask therapy avoids the unwanted dental tipping of upper incisors and lower molars that occurs with conventional tooth-borne anchors.
Question 6: During rapid palatal expansion (RPE), a midline diastema typically appears and then closes spontaneously because:
- The teeth drift apart permanently
- Suture opening pushes incisors apart and roots uprighting closes the diastema (Correct answer)
- The frenulum is always cut during RPE
- Bone fills in between the upper central incisors
Correct answer: Suture opening pushes incisors apart and roots uprighting closes the diastema
As the suture opens, the upper central incisors tip apart, but the transeptal fibers pull the crowns back together as the suture ossifies.
ABO ABO Dentofacial Orthopedics 1
The rapid palatal expander (RPE) creates a midpalatal suture opening.
At what age does this suture typically become interdigitated and difficult to expand non-surgically?