4. adapted from quizlet ryanef123 Ortho 8 - Biology of Ortho Movement (Dr. Suri)

Most critical aspect of orthodontic tooth movement, all ortho requires _______

Periodontal support/ PDL

Which characteristic of human dentition refers to having two successive sets of teeth during a lifetime?

Diphyodont

What type of joint is the tooth to alveolar bone articulation?

Gomphosis

Once implants are place, can they move?

No they are fixed in place (no PDL)

What are the 6 components of the periodontal support?

- Cementum

- Alveolar bone proper

- Alveolar crestal fibers

- Horizontal fibers

- Oblique fibers

- Apical fibers

ID the components of the periodontal support at 1:

Alveolar crestal fibres

ID the components of the periodontal support at 2:

Horizontal fibres

ID the components of the periodontal support at 3:

Oblique fibres

ID the components of the periodontal support at 4:

Apical fibres

ID the components of the periodontal support at 5:

Cementum

ID the components of the periodontal support at 6:

Alveolar bone proper

In what direction are the oblique fibers of the PDL oriented?

Apical towards tooth, Coronal towards alveolar bone

Which type of fiber is most predominant in PDL?

Oblique fibers

Which PDL fibers resist extrustion?

- Alveolar crestal fibers

- Apical fibers

Which PDL fibers resist lateral movements?

Horizontal fibers

Which PDL fibers resist chewing forces?

Oblique fibers

What anchors the tooth to the alveolar bone?

Principal PDL fibers (via Sharpey's fibers)

What is the average width of the PDL?

0.2-0.4mm

What are three types of physiologic tooth movement?

- Tooth eruption

- Migration or drift of teeth

- Changes in tooth position during mastication

Where is periodontal space the widest?

Alveolar crest

Which of the following are tooth eruption theories?

A) Blood pressure

B) Pulp theory

C) Alveolar bone growth

D) Dental Follicle theory

E) Root growth theory

F) Hammock ligament theory

G) Periodontal ligament traction

All of the above!

Which tooth eruption theory?

Vascular pressure beneath the tooth pushes it occlusally.

Blood pressure theory

Which tooth eruption theory?

Growth and proliferation of pulp tissue generates eruptive force.

Pulp theory

Which tooth eruption theory?

Bone deposition beneath the tooth pushes it into the oral cavity.

Alveolar bone growth theory

Which tooth eruption theory?

The dental follicle coordinates bone resorption above and bone formation below the tooth, directing eruption.

Dental Follicle theory

Which tooth eruption theory?

Elongating roots push the crown occlusally.

Root growth theory

Which tooth eruption theory?

A ligament beneath the root acts like a sling and contracts to pull the tooth upward.

Hammock ligament theory

Does the hammock ligament exist?

No - disproven as an artifact during H&E staining

Which tooth eruption theory?

PDL fibroblasts contract and collagen fibers remodel, generating eruptive force.

Periodontal ligament traction theory

Which eruption theory is most widely accepted today?

Periodontal ligament traction theory

Loss of bone, leads to loss of tooth support and loss of equilibrium, which results in what?

Tooth movement

During mastication, contact with force lasts for how long?

Less than 1 second

The force during chewing/biting forces can range from about ___-___kg for light contact up to ___ kg during heavy biting/clenching.

1-2 kg, 50 kg (≈110 lb of force)

What are the muscles of mastication?

- Masseter

- Temporalis

- Medial pterygoid

- Lateral pterygoid

What is the difference between mastication forces, orthodontics forces, and bruxism?

- Mastication: High force, short duration → generally physiologic.

- Orthodontics: Low force, long duration → tooth movement.

- Bruxism: High force, prolonged/repeated duration → can be traumatic to the periodontium.

What is the duration of heavy pressure that results in the following physiologic response?

- PDL fluid incompressible

- Alveolar bone bends

- Piezoelectric signals generated

<1 sec

What is the duration of heavy pressure that results in the following physiologic response:

- PDL fluid expressed

- Tooth moves within PDL space

1-2 secs

What is the duration of heavy pressure that results in the following physiologic response:

- PDL fluid squeezed out

- Tissues compresse

- Immediate pain if pressure is heavy

3-5 seconds

Tooth movement is corrected based on _________ force

Orthodontic

Growth modifications are corrected based on _________ force

Orthopedic

Dentofacial deformities are corrected based on _________ force

Orthognathic

All of the following are factors affecting Tooth Movement EXCEPT:

A. Manner of force application (Continuous, Interrupted, Intermittent)

B. Amount of force (Light, Heavy)

C. Duration of force

D. Direction of force

E. Occlusal function

F. Age

G. Compliance

G. Compliance

What type of force application?

Force never drops to zero between appointments. It gradually decreases but is always present.

Continuous

What type of force application?

Force decreases over time and eventually reaches zero, but the appliance remains in place.

Interrupted

What type of force application?

Force is present only when the appliance is worn; when removed, force immediately becomes zero.

Intermittent (ex: headgear)

What type of force application are elastics?

Interrupted

What is the time threshold, or how long is the duration of force needed to see tooth movement?

Beyond 4-6 hours

The greater the ________ of force, the greater efficiency of tooth movement

duration

All of the following are the fundamental principles of tooth movement EXCEPT:

a. If force is applied over threshold duration tooth movement will occur

b. Tooth movement is a function of alveolar bone

c. Bone removed in some areas and deposited in others

d. Tooth moves through bone carrying its attachment apparatus with it

B - Tooth movement is a function of PDL!!!!!

ID phase of tooth movement:

- Compression of the PDL (w/ fluid moving out)

- The alveolar bone bends

Initial strain/primary displacement phase

How long is the Initial strain/primary displacement phase?

1-3 days

During tooth movement, creation of areas of pressure and tension occur where?

At the tissue level

ID phase of tooth movement:

- Hyalinization

- Cellular recruitment

- Neovascularization

- Cell differentiation

- PDL reorganization

Lag phase

How long is the lag phase?

2-10 weeks

ID phase of tooth movement:

Initial strain/primary displacement phase

What is movement of the tooth without the apex moving in the opposite direction?

Controlled tipping

What is movement of the tooth while the apex moves in the opposite direction?

Uncontrolled tipping

T/F: Under a higher force magnitude on a tooth, histologically we can observe...

- Width of ligament

- Effects blood flow

-Changes number and type of cells at site

True

What type of force is on the left vs the right?

Left - light force

Right - heavy force

All of the following are consequences of heavy forces on the tooth EXCEPT:

A. Cell destruction and decreased vascular supply in the PDL

B. Hyalinization

C. Undermining Resorption

D. Horizontal reduction of approximal alveolar bone may occur

D - A vertical reduction of approximal alveolar bone may occur

At areas of pressure, what type of cells are found?

Osteoclasts

(areas of pressure = resorption of bone)

At areas of tension, what type of cells are found?

Osteoblasts

(areas of tension = bone deposition)

What type of resorption is observed during Light Pressure?

Frontal resorption

What type of resorption?

- The generation of osteoclasts in the PDL space

- Resorption of the front of the alveolar bone (in the direction of pressure)

Frontal resorption

What type of resorption is observed during Heavy Pressure?

Undermining resorption

What type of resorption?

- The generation of osteoclasts within the marrow/medullary spaces to resorb bone, undermining it

Undermining resorption

ID the type of resorption:

Frontal resorption

ID the type of resorption:

Undermining resorption

Define the following:

Cells derived from paravascular connective tissue

Osteoblasts

Define the following:

Cells derived from bone marrow

Osteoclasts

All of the following are ways to ID an osteoclast EXCEPT:

A. Multinucleated giant cells

B. Sit in Howship's lacuna

C. Have ruffled border

D. Decreased acid phosphatase

D - INCREASED

Acid phosphatase is a marker for ________ activity

Osteoclasts

Alkaline phosphatase is a marker for ________ activity

Osteoblasts

During orthodontic movement, what side would you expect to see acid phosphatase?

Pressure side (bone resorption)

During orthodontic movement, what side would you expect to see alkaline phosphatase?

Tension side (bone formation)

Which line represents light forces on tooth movement?

Red line

Which line represents heavy forces on tooth movement?

Purple line

Under light forces, the lag phase is expected to be ______

Shorter

What is the maximum efficiency of tooth movement?

24 hrs/day

Under heavy forces, the lag phase is expected to be ______

Longer

There is an optimal force that can be placed on a tooth for movement. Once that pressure is exceeded, tooth movement will:

A) Plateau and then decrease

B) Decrease

C) Increase

A) Plateau and then decrease

All of the following are clinical characteristics of optimal orthodontic force EXCEPT:

A. Produces rapid tooth movement

B. Minimal patient discomfort

C. Lag phase of tooth movement minimal

D. Marked mobility of teeth

D - NO marked mobility of teeth

All of the following are the histological characteristics of optimal orthodontic force EXCEPT?

A. Maintained vitality of teeth

B. Initiates maximal cellular response

C. Produces undermining resorption

C. Produces FRONTAL resorption

Which type of movement requires the most amount of force (70-120gm) :

A) Tipping

B) Bodily movement (translation)

C) Root uprighting

D) Rotation

E) Extrusion

F) Intrusion

B) Bodily movement (translation)

Which type of movement requires the least amount of force (10-20gm):

A) Tipping

B) Bodily movement (translation)

C) Root uprighting

D) Rotation

E) Extrusion

F) Intrusion

F) Intrusion

Which 3 movements require about the same amount of force (35-60gm):

A) Tipping

B) Bodily movement (translation)

C) Root uprighting

D) Rotation

E) Extrusion

F) Intrusion

A) Tipping

D) Rotation

E) Extrusion

Root uprighting requires an optimal amount of force of what?

50-100 gm

What type of movement is shown here?

Tipping movement

What type of movement is shown here?

Bodily movement

On a tooth experiencing force, what type of cells do we expect to see at pressure spots?

Osteoclasts

On a tooth experiencing force, what type of cells do we expect to see at tension spots?

Osteoblasts

What type of tooth movement ideally produce no areas of compression?

Extrusion

What should you expect if you put a tooth under heavy extrusive forces?

Risk of extraction

What should you expect if you put a tooth under light extrusive forces?

Alveolar bone will follow root

(Periodic radiographic examination is desirable)

What type of tooth movement works around the long axis of the tooth?

- Forces distributed over the entire PDL

- Coupling forces: equal forces in opposite directions

Rotation

what type of force is needed to rotate a tooth?

Coupling forces

What is one of the hardest positions to hold in place for orthodontic movement?

Rotation (1st to relapse because of supracrestal fibers)

What order of orthodontic bends would result in root uprighting?

2nd order bends

What type of tooth movement requires careful control of force magnitude?

- Apical root resorption risk!

Intrusion

ID the Theory of Tooth Movement:

- Movement occurs due to osteoclastic activity at pressure spots and osteoblastic activity at tension spots

Pressure-Tension theory