DMD Orthodontics 2

Question 1

Which functional appliance is a fixed device that positions the mandible forward to correct a Class II malocclusion in a growing patient by altering condylar growth?

Accepted Answer

Herbst appliance

Answer

The Herbst appliance is a fixed functional device that holds the mandible in a protruded position continuously, stimulating condylar adaptation and correcting Class II skeletal discrepancy in growing patients.

Question 2

The ANB angle in cephalometric analysis directly represents which skeletal relationship?

Accepted Answer

Anteroposterior relationship between the maxilla and mandible

Answer

The ANB angle (SNA minus SNB) reflects the anteroposterior discrepancy between the maxillary (A point) and mandibular (B point) bases; the norm is approximately 2°.

Question 3

A patient presents with a unilateral posterior crossbite and an apparent midline shift. Upon opening, the mandibular midline coincides with the maxillary midline. What is the most likely etiology?

Accepted Answer

Functional shift caused by a premature occlusal contact

Answer

When the midlines align on opening but deviate in centric occlusion, it indicates a functional shift where a premature contact deflects the mandible laterally into a unilateral crossbite position.

Question 4

The Hyrax rapid palatal expander achieves skeletal expansion of the maxilla primarily through which mechanism?

Accepted Answer

Opening of the midpalatal suture to produce true skeletal widening

Answer

The Hyrax RPE opens the midpalatal suture through heavy orthopedic forces, producing true skeletal expansion of the maxillary arch — most effective before suture fusion in adolescence.

Question 5

In orthodontic mechanics, 'anchorage' is best defined as:

Accepted Answer

Resistance to unwanted or reactive tooth movement

Answer

Anchorage refers to the resistance offered by teeth, bone, or extraoral structures to the reactive (unwanted) forces generated during orthodontic tooth movement.

DMD - Doctor of Medicine in Dentistry Practice Test

DMD - Doctor of Medicine in Dentistry Practice Test

DMD Orthodontics 2