Lecture 7

Question 1

In a typical force-deflection curve the stiffness of a material is given by what part of the curve?

Answer 1

-Slope of the linear portion (steeper the slope the stiffer the material)

Question 2

What is the range in the force deflection curve?

Answer 2

-It is the distance along the X-axis where permanent deformation occurs (usually taken as the yield point)

Question 3

What is the strength of a wire?

Answer 3

-Stiffness times the range

Question 4

What is the proportional limit in a force-deflection curve?

Answer 4

-The force placed on the wire creates a proportional deflection in the wire ( graph remains linear)

Question 5

What is the spring back in a force deflection curve?

Answer 5

-The position the wire will return to after it has been deflected.

Question 6

What affects the major characteristics of a wire?

Answer 6

• The length
• The shape
• The cross section area

Question 7

Forces that are maintained between activations are known as what type of forces?

Answer 7

-Continuous forces

Question 8

Forces that drop to zero between activations are known as what type of forces?

Answer 8

-Interrupted forces

Question 9

What is an example of an arch wire that gives continuous forces?

Answer 9

-Nickel titanium

Question 10

What is an example of an arch wire that has interrupted forces?

Answer 10

-Stainless steel

Question 11

What type of forces fall to zero when a removable appliance is taken out?

Answer 11

-Intermittent forces

Question 12

What are the optimal intrusive forces?

Answer 12

10-20 grams

Question 13

What are the optimal extrusive forces?

Answer 13

-35-60 grams

Question 14

What type of orthodontic arch wire is strong, stiff, formable, and has been used routinely for many years?

Answer 14

-Stainless steel

Question 15

What type of orthodontic arch wire is softer than stainless steel making it more formable, and then the wire can be heat treated to make it harder before it is inserted into the orthodontic appliance is what type?

Answer 15

-Chromium alloys (Elgiloy)

Question 16

What are two great characteristics of nickel titanium alloys?

Answer 16

• Ability to apply light force over a large range of activations
• Its shape memory and super elasticity

Question 17

What is the weakness of nickel titanium wires?

Answer 17

• Have poor formability

Question 18

What is beta titanium?

Answer 18

-Combination of strength of springiness as well as good formability ( between stainless steel and nickel titanium wires)

Question 19

T/F Orthodontic appliances should be reactivated more frequently than at 3 week intervals

Answer 19

False

-Should not

Question 20

How many days does it take for undermining resorption to occur?

Answer 20

-7-14 days

Question 21

How longer does it take for the PDL regeneration and repair to occur after the tooth has moved?

Answer 21

-7-14 days

Question 22

What happens if you activate an appliance too frequently?

Answer 22

-You can damage the tooth and inhibit the repair process

Question 23

T/F Orthodontic appliance increases the amount of gingival inflammation

Answer 23

True

Question 24

What is the average amount of bone loss from orthodontic treatment?

Answer 24

-.5 mm or less and it rarely exceeds 1 mm

Question 25

T/F In the absence of pathologic factors, a tooth that erupts too much simply caries alveolar bone with it

Answer 25

True

Question 26

T/F When a tooth is intruded or extruded the alveolar bone moves with the tooth

Answer 26

True

Question 27

T/F Unless a tooth erupts into an area of the dental arch, the alveolar bone will not form there

Answer 27

True

Question 28

T/F Radiographically it can not be observed that the PDL space widens during orthodontic tooth movement.

Answer 28

False

- It can be observed

Question 29

THe combination of a wider ligament space and a somewhat disorganized ligament means what will be observed in every patient?

Answer 29

-That there will be some increase in mobility

Question 30

The heavier the force the grater the undermining resorption should be expected and the _________ that will develop,

Answer 30

-Greater the mobility

Question 31

How long does pain typically last when an orthodontic appliance is placed on the teeth?

Answer 31

-2-4 days

Question 32

During tooth movement what do clast cells attack?

Answer 32

• Cementum

- Bone

Question 33

T/F Root remodeling and bone remodeling is a constant feature of orthodontic tooth movement

Answer 33

True

Question 34

Under normal circumstances permanent loss of root structure would only occur why?

Answer 34

-If the repair phase was not able to replace the initially resorbed cementum

Question 35

Shortening of the roots or root resorption occurs when cavities coalesce at the apex so that what occurs?

Answer 35

-Peninsulas of root structure are cut off as islands

Question 36

T/F Shortening of the root doesn’t occur during orthodontic treatment

Answer 36

False

-It can occur

Question 37

T/F Roots become shorter and thinner during orthodontic treatment

Answer 37

False

-They dont get thinner just shorter

Question 38

What is a category 1 root resorption?

Answer 38

-No change in root length

Question 39

What is a category 2 root resorption?

Answer 39

-Slight blunting

Question 40

What is category 3 root resorption?

Answer 40

-Moderate resorption up to 1/4 of root length

Question 41

What is a category 4 root resorption?

Answer 41

-Sever resorption greater than 1/4 of root length

Question 42

What is camouflage orthodontic treatment?

Answer 42

-Moving the teeth into less than ideal positions to compensate for skeletal abnormalities

Question 43

Severe resorption of a localized area typically involve what teeth?

Answer 43

-Maxillary incisors

Question 44

T/F Severe root resorption can occur from parafunctional habits such as tongue thrusting and clenching or grinding.

Answer 44

True

Question 45

What gene has been linked to external apical root resorption?

Answer 45

-Interleukin 1B gene