Exam 2D

Question 1

Definition: elastic limit –> permanent deformation first observed?

Answer 1

proportional limit

Question 2

Definition: point on the stress/strain diagram at which a deformation of 0.1% is measured?

Answer 2

yield point / yield strength

Question 3

Definition: point at which the wire breaks?

Answer 3

failure point

Question 4

3 major properties for force-deflection?

Answer 4

Strength
Stiffness
Range

Question 5

Definition: maximum load the wire can sustain?

Answer 5

ultimate tensile strength

Question 6

What kind of wire can control torque?

Answer 6

rectangular (round can do everything but this)

Question 7

What occurs in stage 1 ortho?

Answer 7

level and align

Question 8

What occurs in stage 2 ortho?

Answer 8

correction of molar relationship and space closure

Question 9

What occurs in stage 3 ortho?

Answer 9

finishing: root paralleling, incisor torque, correction of overbite/overjet, correction of midline, finish occlusion

Question 10

Where is the center of resistance in single-rooted teeth?

Answer 10

a constant: located 1/3 of the root length from the CEJ in single rooted teeth

Question 11

Where is the center of resistance in multi-rooted teeth?

Answer 11

just apical to furcation

Question 12

Definition: the point around which the tooth rotates?

Answer 12

center or rotation

Question 13

Is the center or rotation constant?

Answer 13

no

Question 14

Center of rotation is determined by what?

Answer 14

the type of movement occurring

Question 15

Type of movement caused by Invisalign or spring retainers by single point of force near center of resistance?

Answer 15

uncontrolled tipping

Question 16

Type of movement caused by brackets with multiple forces working at different locations resulting in center of rotation near the apex?

Answer 16

controlled tipping

Question 17

Type of movement where net force results in center of rotation infinitely far from center of resistance and all points on a rigid body move the same amount in the same direction?

Answer 17

translation (bodily movement)

Question 18

Type of movement where net force results in center of rotation at incisal tip of tooth; root and crown move in the same direction; root moves greater distance than crown?

Answer 18

root torque

Question 19

How will a two-couple force system move incisors and molars?

Answer 19

incisors intrude and rotate counter-clockwise

molar will extrude and rotate clockwise