ABO ABO Orthodontic Appliances and Mechanics

Question 1

Which bracket prescription is characterized by built-in torque, tip, and in-out values to reduce the need for wire bending?

Accepted Answer

Preadjusted edgewise bracket

Answer

The preadjusted edgewise (straight-wire) bracket incorporates built-in torque, tip, and in-out compensations to minimize wire adjustments.

Question 2

What is the primary purpose of a transpalatal arch (TPA) in orthodontic treatment?

Accepted Answer

To maintain molar width and prevent molar rotation

Answer

A transpalatal arch connects the upper molars across the palate to maintain their transverse position and prevent unwanted rotation.

Question 3

In the Tip-Edge bracket system, teeth are allowed to tip freely in which phase?

Accepted Answer

Initial leveling phase

Answer

During the initial leveling phase of Tip-Edge mechanics, teeth tip freely to correct vertical and horizontal discrepancies before torquing.

Question 4

Which type of headgear produces the greatest restriction of maxillary forward growth?

Accepted Answer

High-pull headgear

Answer

High-pull headgear directs force superiorly and posteriorly, providing the greatest restriction on forward maxillary growth.

Question 5

What is the function of a Nance holding arch?

Accepted Answer

To prevent mesial drift of upper molars after premolar extraction

Answer

The Nance holding arch uses a palatal button to resist mesial movement of upper molars, preserving space after premolar extraction.

American Board of Orthodontics (ABO) Practice Test