ABO Orthodontic Biomechanics 5

Question 1

In the sliding mechanics method of space closure, resistance to movement is chiefly due to:

Accepted Answer

Friction between the archwire and bracket slot

Answer

Sliding mechanics require overcoming friction/binding between the wire and bracket during tooth translation.

Question 2

Frictionless (loop) mechanics differ from sliding mechanics because they:

Accepted Answer

Use closing loops to deliver force without sliding along the wire

Answer

Loop mechanics activate bends/loops to move teeth without the tooth sliding along the archwire, avoiding friction.

Question 3

A stiffer (larger cross-section or higher-modulus) archwire generally delivers:

Accepted Answer

Higher force per unit of deflection

Answer

Increased stiffness raises the load-deflection rate, delivering more force for a given activation.

Question 4

Nickel-titanium archwires are favored in early alignment because they:

Accepted Answer

Provide light, continuous force over a wide range of deflection (superelasticity)

Answer

NiTi wires exhibit superelasticity, giving light, relatively constant forces even when heavily deflected.

Question 5

First-order (in-out) bends in an archwire control tooth position in which dimension?

Accepted Answer

Faciolingual (labiolingual) crown position

Answer

First-order bends adjust the in-out (faciolingual) position of the crowns along the arch.

American Board of Orthodontics (ABO) Practice Test