MJDF Orthodontics 3

Question 1

The most common reason for prolonged retention of a primary tooth beyond its normal exfoliation date is:

Accepted Answer

Absence of the permanent successor

Answer

Hypodontia (absence) of the permanent successor removes the normal eruptive pressure that drives primary tooth exfoliation, leading to its retention.

Question 2

External apical root resorption during orthodontic treatment is most strongly associated with:

Accepted Answer

Heavy forces, prolonged treatment, and intrusion movements

Answer

Heavy forces, lengthy treatment duration, and intrusive tooth movements place the greatest stress on root apices and are the strongest risk factors for external apical root resorption.

Question 3

In a 10-year-old patient with a palatally displaced upper permanent canine, what is the first-line interceptive management?

Accepted Answer

Extraction of the retained primary canine

Answer

Extraction of the retained primary canine at age 10–11 can redirect the ectopic canine and achieve spontaneous eruption in approximately 64–78% of cases, avoiding surgery.

Question 4

The Twin Block appliance is primarily indicated for the treatment of which malocclusion?

Accepted Answer

Class II Division 1 malocclusion during the growth phase

Answer

The Twin Block is a two-part removable functional appliance designed to posture the mandible forward, correcting Class II Division 1 malocclusion during active growth.

Question 5

Point A (Subspinale) on a lateral cephalogram represents:

Accepted Answer

The deepest point on the concavity of the anterior maxilla

Answer

Point A is the deepest point on the concavity of the anterior surface of the maxilla and is used in the ANB analysis to represent the anteroposterior position of the maxilla.

MJDF Part 1 Practice Test

MJDF Part 1 Practice Test

MJDF Orthodontics 3