Profitt Orthodontics

Question 1

What is the force applied to the teeth by the lips?

Answer 1

5gm

Question 2

What is the force applied to the teeth by the tongue?

Answer 2

5-10 gm

Question 3

What is undermining resorption?

Answer 3

Heavy forces leads to rapidly developing pain, necrosis of the cellular elements with the PDL

Question 4

What is frontal resorption?

Answer 4

Light forces are compatible with cell survival within the PDL and a remodeling of the tooth socket by relatively painless resorption

Question 5

Do you want undermining or frontal resorption with orthodontic movement?

Answer 5

Frontal resorption

Question 6

Name the two major theories of orthodontic movement.

Which one is the correct theory?

Answer 6

1. Bioelectric theory
2. Pressure-tension theory

Both MOA play a part in biologic control of tooth movement

Question 7

What is the bioelectric theory of orthodontic movement?

Answer 7

Relates tooth movement at least in part to changes in bone metabolism controlled by the electric signals that are produced when alveolar bone flexes and bends

Question 8

What is the pressure-tension theory of orthodontic movement?

Answer 8

relates to tooth movement to cellular changes produced by chemical messengers, traditionally thought to be generative by alterations in blood flow through the PDL

Question 9

Describe the piezoelectricity with tooth movement

Answer 9

Deformation of the crystal structure produce a flow of electric current as electrons are displaced from one part of the crystal lattice to another

Question 10

With the pressure-tension theory, blood flow is (decreased/increased) where the PDL is compressed.

Answer 10

Blood flow is decreased where the PDL is compressed

Question 11

With the pressure-tension theory, blood flow is (decreased/increased) where the PDL is under tension?

Answer 11

The blood flow is either maintained or increased where the PDL is under tension

(if over stretched, then blood flow will decrease transiently)

Question 12

Tooth movement shows three stages:

Answer 12

1. Alteration in blood flow associated with pressure within the PDL
2. Formation and/or release of chemical messengers
3. Activation of cells

Question 13

What two messengers play a role in tooth movement?

Answer 13

Prostaglandin E and IL-1

Question 14

What cells work on bone adjacent to the compressed PDL?

Answer 14

Osteoclasts

Question 15

What cells work on bone adjacent to the tension side of the PDL?

Answer 15

Osteoblasts for bony remodeling

Question 16

Prostaglandin E stimulates (osteoblast/osteoclast)

Answer 16

Both osteoblasts and osteoclasts

Question 17

What is hyalinized in reference to PDL?

Answer 17

Represents the inevitable loss of all cells when the blood supply is totally cut off (occurs before undermining resorption)

Question 18

Undermining resorption (delays/quickness) tooth movement

Answer 18

Undermining resorption delays tooth movement

Question 19

What is the simplest form of orthodontic movement?

Answer 19

Tipping - when a single force is applied against the crown of a tooth

Question 20

What are the different forms of orthodontic movement?

Answer 20

1. Tipping
2. Bodily movement (translation)
3. Root uprighting (radicular)
4. Rotation
5. Extrusion
6. Intrusion

Question 21

What are the optimal forces for orthodontic movement of:

1. Tipping
2. Bodily movement (translation)
3. Root uprighting
4. Rotation
5. Extrusion
6. Intrusion

Answer 21

Question 22

With tipping where:

a. is the center of resistance
b. is the PDL compressed

Answer 22

Center of resistance is located ½ way down the root

PDL is compressed near the root apex on the same side as the spring and at the crest of the alveolar bone on the opposite from the spring

DO NOT excess force of ~50gm

Question 23

How does bodily movement (translation) occur?

Answer 23

Two forces are applied simultaneously to the crown of a tooth (i.e. apex and crown move in the same direction the same amount)

TWICE as much of the force needed for tipping is needed for translation

Question 24

Why are the forces for rotation about the same as needed for tipping?

Answer 24

It is impossible to apply a rotational force without tipping so forces are the same

Question 25

What is special about extrusion?

Answer 25

There is no PDL compression. There is ONLY tension on PDL Same force as for tipping

Question 26

What is special about intrusion?

Answer 26

Light forces ONLY to avoid high concentration of force at the apex

Question 27

What is the order of easiest to hardest orthodontic movement?

Answer 27

extrusion, tipping, radicular, rotation, translation, intrusion.

Question 28

What is the threshold for force duration in human orthodontic movement?

Answer 28

4-8 hours

Question 29

Define Continuous force

Answer 29

Force maintained at some appreciable fraction of the original form one patient visit to the next

Question 30

Define Interrupted force

Answer 30

Force levels decline to zero between activations

Question 31

Define Intermittent Force

Answer 31

Force levels decline abruptly to zero intermittently (use of a retainer or incline plane, elastics)

Question 32

How long does undermining resorption require?

Answer 32

7-14 days

Question 33

A, B, C, represent what? (Ideal spring; Interrupted force; Intermittent force)

Answer 33

A: Ideal spring B: Interrupted force C: Intermittent force

Question 34

What two drugs depress the response of orthodontic force?

Answer 34

Bisphosphonates - inhibit osteoclastic mediated bone resorption Prostaglandin Inhibitors (steroids and NSAIDs, etc) -Ibuprofen, aspirin have little/no effect on tooth movement at certain doses

Question 35

Define Reciprocal Tooth Movement

Answer 35

Forces applied to teeth and to the arch segment are equal and so is the force distribution in the PDL

Question 36

What is Reinforced Anchorage

Answer 36

Anchorage of the posterior teeth, to retract an anterior tooth/teeth Changes the ratio of the root surface area so more pressure in the PDL of the anterior teeth

Question 37

What is stationary anchorage?

Answer 37

Less descriptive term than reinforce anchorage; advantage that can be obtained by pitting bodily movement of one group of teeth against tipping of another

Question 38

What is anchorage value of a tooth?

Answer 38

Is roughly equivalent to its root surface area

Question 39

What is cortical Anchorage?

Answer 39

Cortical bone is more resistant to resorption and tooth movement slows when it contacts it. Not usually used technique because teeth move along cortical bone (unless there is an old healed extraction site)

Question 40

What is Skeletal (Absolute) Anchorage?

Answer 40

Using a bone implant with no tooth movement except what was desired

Question 41

Short term and/or Chronic use of prostaglandin inhibitors can inhibit tooth movement?

Answer 41

Short term with a modest dose over 3-4 days does not inhibit tooth movement. Chronic use of PG inhibitors can inhibit tooth movement

Question 42

What effect does orthodontic movement have on the pulp?

Answer 42

With light force, there is little if any effect on the pulp With heavy forces (poor control of ortho movement) the tooth can lose its vitality

Question 43

Does the tooth root remodel with orthodontic movement?

Answer 43

Yes, cementum is removed and replaced with movement. It is a constant feature of orthodontic movement

Question 44

What are three distinct forms of shortening of tooth roots when etiology is resorption?

Answer 44

1. Moderate Generalized Resorption (occurs with longer duration of treatment) 2. Severe Generalized Resorption (rare) 3. Severe Localized Resorption (can be common with excessive force)

Question 45

What are the effects of treatment on the height of alveolar bone?

Answer 45

Excessive loss of crestal bone height is almost never seen with orthodontic treatment (loss of \<0.5mm may occur)