ABO ABO Retention and Stability 3

Question 1

The Ricketts analysis dimension most predictive of post-treatment lip stability is the:

Accepted Answer

E-line (esthetic plane) relationship of the lips

Answer

Ricketts' E-line measures lip position relative to the nose and chin, and it is a key predictor of facial soft-tissue stability after orthodontic treatment.

Question 2

Which statement about lower incisor position and long-term stability is most supported by orthodontic evidence?

Accepted Answer

Maintaining lower incisors near their pre-treatment position improves stability

Answer

Research consistently shows that keeping lower incisor positions close to pre-treatment values reduces the risk of crowding relapse.

Question 3

Nighttime-only retainer wear is typically appropriate beginning at which stage?

Accepted Answer

After approximately one year of full-time wear

Answer

After approximately one year of full-time retainer wear to allow periodontal reorganization, most patients can transition to nighttime-only wear.

Question 4

Canine-to-canine intercanine width changes during orthodontic treatment have the highest relapse rate because:

Accepted Answer

The intercanine dimension is closely controlled by the surrounding musculature and pre-treatment anatomy

Answer

The intercanine width is strongly dictated by the functional envelope of the muscles and pre-existing skeletal architecture, making changes highly unstable.

Question 5

Which radiographic finding on the ABO case presentation may indicate a problem with long-term stability?

Accepted Answer

Significant root resorption of anterior teeth

Answer

Significant root resorption reduces root surface area available for the periodontal ligament, potentially compromising tooth support and increasing mobility.

American Board of Orthodontics (ABO) Practice Test

American Board of Orthodontics (ABO) Practice Test

ABO ABO Retention and Stability 3