ABO Orthodontic Biomechanics

Question 1

What are the three orders of tooth movement in orthodontic wire bending?

Accepted Answer

First order (in-out), second order (tip/angulation), and third order (torque/inclination)

Answer

Fast, medium, and slow movements

Answer

Upper, middle, and lower tooth movements

Answer

Horizontal, vertical, and rotational only

Question 2

What is anchorage in orthodontics?

Accepted Answer

Resistance to unwanted tooth movement, using teeth, bone, or devices as a stable base to move other teeth

Answer

A type of dental cement

Answer

The foundation of a dental office

Answer

How braces are attached to teeth

Question 3

What is the difference between NiTi and stainless steel archwires?

Accepted Answer

NiTi is superelastic with shape memory for initial alignment; stainless steel is stiffer for precise tooth positioning and finishing

Answer

They are made of the same material

Answer

NiTi is only used for adults

Answer

Stainless steel is more flexible than NiTi

Question 4

What is a temporary anchorage device (TAD)?

Accepted Answer

A small biocompatible screw placed in bone to provide absolute anchorage for orthodontic tooth movement

Answer

A temporary bracket that falls off easily

Answer

A removable retainer

Answer

A type of headgear

Question 5

What forces are optimal for orthodontic tooth movement?

Accepted Answer

Light, continuous forces (25-75g for tipping, 100-150g for bodily movement) that promote healthy tissue remodeling

Answer

Maximum force for fastest movement

Answer

Intermittent heavy forces

Answer

No force is needed with modern braces

Question 6

What is the center of resistance of a tooth?

Accepted Answer

The point where a single force produces bodily movement without rotation, located approximately at the middle third of the root

Answer

The center of the tooth crown

Answer

The tip of the root

Answer

The point where the bracket is bonded