DMD Orthodontics 3

Question 1

Which radiographic finding is the most reliable indicator of orthodontically induced external apical root resorption (EARR)?

Accepted Answer

Shortened root length with a blunted or pipette-shaped apex

Answer

EARR appears on periapical radiographs as a shortening of root length, often with a blunted, truncated, or pipette-shaped apex, confirming loss of root structure.

Question 2

The Tweed analysis uses a triangle formed by three cephalometric measurements. Which set of angles comprises the Tweed triangle?

Accepted Answer

FMA, FMIA, IMPA

Answer

The Tweed triangle consists of FMA (Frankfort-mandibular plane angle), FMIA (Frankfort-mandibular incisor angle), and IMPA (incisor-mandibular plane angle), which together always sum to 180°.

Question 3

Dental transposition is defined as which of the following tooth anomalies?

Accepted Answer

Positional interchange of two adjacent teeth occupying each other's normal position

Answer

Dental transposition is the positional interchange of two adjacent teeth, most commonly involving the maxillary canine and first premolar, so each tooth erupts in the other's normal position.

Question 4

Anterior open bite malocclusion that develops during the mixed dentition is most commonly associated with which parafunctional habit?

Accepted Answer

Digit sucking (thumb/finger) or tongue thrusting

Answer

Digit sucking and tongue thrusting exert persistent forces on the dentition that tip the upper incisors labially, depress lower incisors, and prevent anterior vertical overlap, resulting in an open bite.

Question 5

Which type of retainer provides the most stable long-term retention for lower anterior teeth after orthodontic alignment, reducing the risk of relapse?

Accepted Answer

Bonded fixed lingual retainer

Answer

A bonded fixed lingual retainer cemented to the lower canines or all six anterior teeth provides continuous, compliance-independent retention, which is most effective for preventing lower incisor relapse long-term.

DMD - Doctor of Medicine in Dentistry Practice Test

DMD - Doctor of Medicine in Dentistry Practice Test

DMD Orthodontics 3