4th class

Question 1

Orthodontic treatment is based on the principle that if ________ is
applied to a tooth, tooth movement will occur as the bone around the tooth
remodels.

Answer 1

prolonged pressure

Question 2

Orthodontic treatment is based on the principle that if prolonged pressure is
applied to a tooth, tooth movement will occur as the bone around the tooth
_______.

Answer 2

remodels

Question 3

Tooth movement is primarily a ________ phenomenon because

the bony response is mediated by the periodontal ligament.

Answer 3

periodontal ligament

Question 4

PDL occupies a space approximately ___ mm in width around all parts of the root.

Answer 4

0.5 mm

Question 5

_____ consists of:
• A network of parallel collagenous fibers.
• Inserting into cementum of the root surface on one side and into a relatively dense bony plate, the lamina dura, on the other side.
• Cellular elements.
• Including mesenchymal cells of various types along with vascular and neural elements.
• Tissue fluids.

Answer 5

PDL

Question 6

Two possible control elements, ______ and ______ in the
PDL that affects blood flow, are contrasted in the two major theories of
orthodontic tooth movement.

Answer 6

biologic electricity and pressure-tension

Question 7

The ______ theory relates tooth movement at least in part to changes in
bone metabolism controlled by biologic electricity that are produced by light
pressure against the teeth.

Answer 7

bioelectric

Question 8

The _______ theory relates tooth movement to cellular changes
produced by chemical messengers by alterations in blood flow through the
PDL.

Answer 8

pressure–tension

Question 9

Pressure and tension within the PDL, by reducing (pressure) or increasing
(tension) the ______ of blood vessels in the ligament space, could certainly
alter blood flow.

Answer 9

diameter

Question 10

The pressure–tension theory (classic theory), relies on ______ rather than electric signals as the stimulus for cellular differentiation and ultimately tooth movement.

Answer 10

chemical

Question 11

_________ are important in the cascade of events that lead to remodeling of alveolar bone and tooth movement.

Answer 11

Chemical messengers

Question 12

Both _______ of tissues and _________ can cause chemical messenger release resulting in orthodontic movement.

Answer 12

mechanical compression; changes in blood flow

Question 13

On the _____ side of tooth that is moving, the chemical mediators will stimulate osteoclasts to resorb bone

Answer 13

Pressure side

Question 14

On the _____ side of tooth that is moving, the chemical mediators will stimulate osteoblasts to build bone to occupy the space made by the movement

Answer 14

Tension side

Question 15

Whta are the 2 types of mediators used in orthodontic movement?

Answer 15

Cytokines and Prostaglandins

Question 16

______ appears to be the
mechanoreceptor in PDL cells, and its compression is at least
part of the reason that PgE2 is released.

Answer 16

Focal Adhesion Kinase (FAK)

Question 17

_____ and ______ levels increase within

the PDL within a short time after the application of pressure.

Answer 17

Prostaglandin and Interleukin-1 Beta

Question 18

Two types of drugs are known to depress the
response to orthodontic force and may influence
current treatment:

Answer 18

Corticosteroids / NSAIDs

Bisphosphonates

Question 19

What is the most important chemical mediator in orthodontic tooth movement?

Answer 19

PGE2

Question 20

Most over-the-counter analgesics are _____ and therefore are prostaglandin inhibitors.

Answer 20

NSAIDs

Question 21

The major exception of NSAIDs which do not inhibit PGE2 is _______ , which acts centrally rather than peripherally.

Answer 21

Acetaminophen (Tylenol)

Question 22

•They act as specific inhibitors of osteoclast-mediated
bone resorption.
•As the result, the bone remodeling necessary for tooth
movement is slower in patients on this medication.

Answer 22

Bisphosphonates

Question 23

For a tooth to move, osteoclasts must be formed so
that they can remove bone from the area adjacent to
the _______ part of the PDL.

Answer 23

compressed

Question 24

Osteoblasts also are needed to form new bone on the
______ side and remodel resorbed areas on the
pressure side.

Answer 24

tension

Question 25

_____ forces are compatible with survival of cells within the
PDL and a remodeling of the tooth socket by a relatively
painless “frontal resorption” of the tooth socket.

Answer 25

Lighter

Question 26

Lighter forces are compatible with survival of cells within the
PDL and a remodeling of the tooth socket by a relatively
painless _____ resorption of the tooth socket.

Answer 26

“frontal resorption”

Question 27

_____ forces lead to rapidly developing pain, necrosis of
cellular elements within the PDL, and the phenomenon of
“undermining resorption” of alveolar bone near the affected
tooth.

Answer 27

•Heavy

Question 28

•Heavy forces lead to rapidly developing pain, necrosis of
cellular elements within the PDL, and the phenomenon of
_____ resorption of alveolar bone near the affected
tooth.

Answer 28

“undermining resorption”

Question 29

•When ___ but prolonged force is applied to a tooth:
•PDL partially compressed.
•Blood flow decreases.
•Within a few hours, mediators release.
•Changes in the chemical environment produce cellular
differentiation and activity.
•The tooth moves in its socket

Answer 29

light forces

Question 30

_____ forces
•If the sustained force against the tooth is great enough to
totally occlude blood vessels and cut off the blood supply to
an area within the PDL.
•Cells within the compressed area of the PDL being
stimulated to develop into a sterile necrosis forms within the
compressed area.
•Because of its histologic appearance as the cells disappear, an
avascular area in the PDL traditionally has been referred to as
hyalinized.
•After a delay of several days, cellular elements begin to
invade the necrotic (hyalinized) area.
•Osteoclasts appear within the adjacent bone marrow spaces
and begin an attack on the underside of the bone
immediately adjacent to the necrotic PDL area.
•When hyalinization and undermining resorption occur, an
inevitable delay in tooth movement results

Answer 30

Heavy forces

Question 31

If there is an avascular area in the PDL that has been cut off from blood supply and necroses, it is called _____

Answer 31

Hyalinized