Principles & Techniques 2 Flashcards by Jordan Sanger

What forces oppose eruption of teeth?

chewing and soft tissue forces

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______ pressures of ______ duration are more significant in producing tooth movement than heavy intermittent pressures like chewing.

light pressures of long duration

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Teeth that are in function erupt at a rate that parallels the rate of what?

the rate of vertical growth of the mandibular ramus

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As the _____ grows longer it creates space between the maxillary arch and mandibular arch.

ramus

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Before the tooth is in occlusion, it’s primarily effected by forces _________ eruption.

promoting

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After the tooth is in occlusion, it’s primarily effected by forces _________ eruption.

opposing

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The total eruption path of a first permanent molar is about _____ cm.

2.5 cm

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Why do ankylosed teeth appear “sunken” down compared to adjacent teeth?

Because half of the eruption path (i.e. 1.25 of 2.5cm) is achieved after tooth is on occlusal level. Ankylosed tooth will stop at the halfway point.

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How can a lateral tongue thrust affect eruption of teeth?

It can prevent teeth from fully erupting to fill the space created by ramus growth. Causes a posterior open bite.

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What treatment options do we have for ankylosed permanent teeth?

Extraction, crowns, or surgery (i.e. distraction osteogenesis)

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When is extraction of an ankylosed primary tooth recommended?

When it drops below the height of contour and there is not an adult tooth to replace it.

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For ankylosed primary teeth without an adult tooth replacement, what options are there for treatment?

extraction, build-up of primary tooth, or leave as is

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During adult life, teeth continue to _______ at an extremely slow rate.

erupt

opposing forces required to keep teeth from hyper eruption

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How does wear of teeth affect vertical dimension?

Vertical dimension is maintained by further eruption of teeth

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The bone remodeling involved in orthodontic treatment is mediated by the _____.

PDL

PDL phenomenon

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What happens if the PDL is destroyed during orthodontic treatment?

ankylosis

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Under normal circumstances, how wide is the PDL?

0.5mm

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What constantly remodels the collagens of the PDL?

fibroblasts and fibroclasts

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What remodels and recontours the alveolar bone and cementum?

osteoclasts and cementoclasts, respectively

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What kind of nerve endings are in the PDL?

unmyelinated free nerve endings for proprioception and pain

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What does the fluid function as in the PDL?

A shock absorber for the tooth

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If pressure is maintained on the tooth, what happens to the PDL fluid?

It is rapidly expressed to create more fluid pressure in the PDL (pain is felt)

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On mandibular anterior teeth, does the lip or tongue put more pressure on the teeth?

tongue

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Is lip or tongue pressure greater on maxillary incisors?

lip

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______ ___________ of the PDL implies that there is a threshold for orthodontic force, and any force less than this wouldn't move the tooth.

active stabilization of the PDL

What is the threshold for orthodontic force (in g/square cm)

5-10 grams/square cm

Active stabilization produced by _________ _______ in the PDL explains why teeth are stable in the presence of imbalanced (natural) pressures.

metabolic effects

What is a lip bumper?

Appliance that holds the lip away from the anterior teeth to allow for maximum forward movement of teeth

What is the envelope of stability?

Teeth occupy a space where soft tissue pressures are in equilibrium (but remember it isn't balanced pressure)

After a tooth emerges into the mouth further eruption depends on metabolic events within the PDL including...

formation of cross-linkages and maturational shortening of collagen fibers.

If a tooth is moved, does the bone and gingiva follow the tooth?

Yes

When the alveolar bone socket bends (acting as shock absorber) it generates a ___________ _______.

Piezoelectric current

What do piezoelectric currents do?

They stimulate skeletal regeneration and repair, which is how bone adapts to functional demands

What two unusual characteristics do piezoelectric signals have?

An initial "quick decay rate" that quickly reduces to zero within a second. An equal signal of opposite direction when the force is released.

Piezoelectric signals are the migration of ________ when the crystal structure of bone is deformed.

electrons

When a maintained force bends the alveolar bone, what happens to electrons in the crystal structure?

structure is stable and electrons don't move

When a maintained force on the alveolar bone is released, what happens to the electrons in the bone's crystals?

crystal returns to original shape and electrons reverse direction back toward the original position

Small voltages seen in fluid ions of the bone fluid are called a ________ _________, and have a rapid onset and alteration (like piezoelectric signals)

streaming potential

Without streaming potentials or piezoelectric currents, what happens to bone?

skeletal atrophy

What does the AcceleDent appliance claim?

That vibration of teeth will shorten length of orthodontic treatment. (but it's a lie!)

The classic theory of orthodontic tooth movement relies on ________ rather than electrical signals to stimulate cellular differentiation.

chemical signals

What two things are necessary for chemical signal release to cause differentiation seen in orthodontics?

mechanical compression of tissues, and change in blood flow

Mechanical effect on the PDL causes the release of what?

cytokines, prostaglandins, and other chemical messengers

Will there be more blood flow to the compressed or stretched PDL?

stretched

What chemical messengers are important in cellular differentiation?

PG-E, IL-1beta, cAMP

Is release of prostaglandins a primary or secondary response to pressure?

primary

How long of sustained pressure does it take for cAMP levels to increase?

4-6 hours (therefore, orthodontic appliance must be worn for 6+ hours to facilitate tooth movement)

What happens to the PDL if too much pressure is placed on the tooth in orthodontics?

sterile necrosis of PDL (aka hyalinized) due to ischemia

Differentiation of _________ isn't possible without adequate blood flow to the PDL.

osteoclasts

When blood flow to the PDL is cut off, what kind of resorption happens?

undermining resorption

Where do osteoclasts come from during undermining resorption?

adjacent marrow spaces outside the alveolar socket

Undermining resorption causes tooth movement to take ____ time.

more time

_______ resorption happens when light, continuous force is applied and blood flow to PDL is maintained.

frontal resorption

Frontal resorption causes tooth movement to take ____ time.

less

During frontal resorption, bone is ______ on the tension side of PDL and ________ on the pressure side.

formed, remodeled

What kind of resorption results in smooth continuous tooth movement?

frontal resorption

What kind of resorption causes more pain?

undermining resorption

Which kind of resorption is the rate limiting step in tooth movement?

undermining resorption

clinically, what kind of resorption happens during tooth movement?

both frontal and undermining

Is there evidence to suggest self-ligating brackets accelerate tooth movement?

Nope.

Does lateral expansion of the dental arch by self-ligating brackets "grow" buccal alveolar bone?

Is lateral expansion of the dental arch by self-ligating bracket systems comparable with lateral expansion gained by rapid maxillary expansion (RME) followed by conventional edgewise treatment?

Is lateral expansion of the dental arch gained by self-ligating bracket systems stable in the long term?

Do self-ligating bracket systems provide lower clinical forces compared with conventional brackets?

No, they may even cause more forces

Do patients treated with self-ligating bracket systems experience less pain during treatment?

In what age range and which teeth are likely experience dental trauma?

7-10 years old, and the anterior incisor region

What do we worry about happening to replanted avulsed teeth?

- periodical abscess - internal root resorption - ankylosis

Should you replant primary teeth?

No, you fool

What are some good things to transport an avulsed tooth?

Saline, milk, saliva, water

If the tooth has been out for less than an hour, what should you do?

Replant immediately, clean with water or saline the root off but do NOT touch the root surface

If the tooth has been avulsed for more than an hour, what should you do?

Soak tooth in fluoride solution for 20 min, rinse with saline, and replant

How do you treat the socket of an avulsed tooth?

Do NOT curette, do NOT vent, do NOT make flap, gently aspirate without entering socket

What should you do to manage soft tissues?

tightly suture, especially if in cervical region

How long should you leave a splint in place to treat an avulsed tooth?

7-10 days

What are possible drug considerations in conjunction with treating avulsed teeth?

systemic antibiotics, refer to physician for tetanus, chlorhexidine rinse, analgesics