ABO ABO Retention and Stability 1

Question 1

Which factor is most commonly cited as a cause of post-treatment lower incisor crowding recurrence?

Accepted Answer

Late mandibular growth and forward drift of lower teeth

Answer

Late mandibular growth combined with anterior soft tissue pressure and mesial drift causes lower incisor crowding to recur after treatment.

Question 2

A Hawley retainer differs from a clear vacuum-formed retainer primarily in that it:

Accepted Answer

Allows minor tooth movement and easy modification by the clinician

Answer

Hawley retainers have a labial bow that can be adjusted by the clinician, allowing minor tooth movement corrections during the retention phase.

Question 3

Which type of teeth movement has the LEAST long-term stability after orthodontic treatment?

Accepted Answer

Expansion of the lower intercanine width

Answer

Expansion of the lower intercanine width is highly unstable because it is strongly determined by the pre-treatment dimensions and muscular environment.

Question 4

A fixed lingual retainer bonded from canine to canine on the lower arch is most effective for:

Accepted Answer

Maintaining lower incisor and canine alignment long-term

Answer

Bonded lingual retainers attached canine-to-canine are highly effective at preventing lower anterior crowding relapse.

Question 5

The fibrotomy (circumferential supracrestal fiberotomy, CSF) procedure is performed to:

Accepted Answer

Reduce relapse of rotational corrections by severing the supracrestal fibers

Answer

CSF severs the supracrestal gingival fibers that tend to pull rotated teeth back toward their original position after correction.

American Board of Orthodontics (ABO) Practice Test

American Board of Orthodontics (ABO) Practice Test

ABO ABO Retention and Stability 1