ABO ABO Growth and Development 2

Question 1

The Demirjian method for dental age assessment is based on which criterion?

Accepted Answer

Seven lower-left permanent tooth calcification stages on panoramic radiograph

Answer

The Demirjian method scores the calcification stage (A–H) of seven lower-left permanent teeth on a panoramic radiograph to estimate dental age.

Question 2

Skeletal age assessment using hand-wrist radiographs identifies peak pubertal growth using which landmark?

Accepted Answer

Appearance and fusion of the sesamoid bone of the thumb (adductor pollicis)

Answer

The sesamoid bone of the thumb appears shortly before peak height velocity, making it a useful landmark for timing orthopedic interventions.

Question 3

In a patient with a Class II skeletal pattern, late mandibular growth is generally considered:

Accepted Answer

Favorable, as mandibular growth tends to reduce the ANB angle

Answer

Continued forward mandibular growth in a Class II patient tends to reduce the ANB angle and improve the skeletal relationship, which is favorable for long-term orthodontic stability.

Question 4

The Bolton ratio analysis compares which measurements to evaluate tooth-size discrepancy?

Accepted Answer

Sum of mesiodistal widths of all 12 lower anterior teeth vs. all 12 upper anterior teeth (overall ratio) or 6 vs. 6 (anterior ratio)

Answer

The Bolton analysis uses the ratio of the sum of mesiodistal widths of the lower 12 teeth to upper 12 teeth (overall) and lower 6 to upper 6 (anterior) to detect tooth-size discrepancies.

Question 5

Timing orthodontic Class III camouflage treatment in a growing patient is challenging because:

Accepted Answer

Continued mandibular growth may worsen the skeletal discrepancy after dental compensation is complete

Answer

Dental compensations achieved during orthodontic treatment can be undone if the underlying skeletal Class III pattern continues to progress with late growth.

American Board of Orthodontics (ABO) Practice Test

American Board of Orthodontics (ABO) Practice Test

ABO ABO Growth and Development 2