Periodontium I Flashcards

1
Q

What is the periodontium?

What 3 structures make it up?

A

Tissues that invest and support the tooth

  • Alveolar process
  • Cementum
  • PDL
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2
Q

When does the periodontium develop?

A

Series of complex interactions of mesenchymal, HERS, and dental follicle

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3
Q

What are the gomphoses?

A

Fibrous peg-in-socket joint

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4
Q

What is the fx of teeth?

A

Survive cycling loading over time

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5
Q

What are the origins of the periodontium?

A

Osteoblasts - Surrounding mesenchymal (NOT ECTOMESENCHYME) tissues

Cementoblasts - HERS/follicle cells - Ectomesenchymal cells

PDL fibroblasts - Follicle cells/ectomesenchymal cells

Odontoblasts - Form dentin part of the cemento-dental junction, dental papilla

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6
Q

T/F - The periodontium contains 3 out of the 4 types of mineralized tissues found in the oral cavity.

A

TRUE

Bone, dentin, cementum
—NOT ENAMEL

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7
Q

What is avulsion?

A

Traumatic removal of teeth

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8
Q

The alveolar process is formed by what?

A

Intramembranous ossification

-Mesenchyme direct to bone - NO CARTILAGE INTERMEDIATE

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9
Q

When does the alveolar process form?

A

8th week of uterine life

  • Tooth germs contained in horseshoe-shaped grooves of the mandible and maxilla
  • Crypts develop around tooth germs, such that they eventually form the sockets
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10
Q

T/F - The alveolar process develops substantially during tooth eruption, under the influence of the dental follicle.

A

TRUE

-Remodeled thru-out life

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11
Q

What is an anodontic individual?

A

Alveolar process development impaired

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12
Q

What are the differences b/t alveolar bone proper and supporting alveolar bone?

A

Alveolar bone proper (right around tooth)
-Compact bone
—Cribiform plate, lamina dura

Supporting alveolar bone (supports the compact bone around the tooth)
-Compact and trabecular bone
—Compact: Cortical plates
—Trabecular: Central spongiosa

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13
Q

What are the 3 parts of the alveolar bone proper and describe them?

A

Cribriform plate - Volkmann’s canals running thru it

Lamina dura - Area of PDL attachment

Bundle bone - Sharpey’s fibers (PDL) embedded in bone

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14
Q

T/F - W/o the dental follicle, a tooth will NOT erupt.

A

TRUE

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15
Q

Tell me about the inner part of the alveolar bone proper.

A

Remodeling rate my be high due to constant adaptation to tooth movements
—Consists of woven bone, but some lamellar bone is present
—Smooth surface in young individuals, but comes rougher with age

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16
Q

Tell me about the outer portion of the alveolar bone proper.

A

Lamellar bone, continuous with supporting alveolar bone

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17
Q

Tell me about the cortical plate of the supporting alveolar bone.

A

Inner - Lingual and palatal surface

Outer - Labial and buccal surface

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18
Q

What is the alveolar crest?

A

Junction of cortical plate and alveolar bone proper

-Thinner in maxilla, thicker in premolars and molar region of mandible

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19
Q

Tell me about the central spongiosa.

A

Trabecular bone supporting alveolar bone proper and cortical plate

Marrow - Red (hemopoietic in young, yellow in aged

20
Q

T/F - Spongiosa is more prevalent than mandible.

A

TRUE

21
Q

T/F - Spongiosa is often absent/diminished in anterior region of both jaws.

A

TRUE

22
Q

Tell me about the two parts of the bone septa.

A

Interradicular septum
-Bony septum b/t roots of a single tooth

Interalveolar septum
-Bony septum b/t adj teeth

23
Q

What are 4 functions of alveolar bone?

A

Protection and structure of the socket for the tooth to rest in

Attachment of Sharpey’s fibers of the PDL which are embedded in bone

Support of tooth roots, esp facial and lingual

Distribution of loading from the tooth and PDL to the surrounding bone

24
Q

Ectomesenchymal cells from the _________ _________ differentiate into fibroblasts which produce and organize collagen fibers, generally in an oblique orientation.

A

Dental follicle

25
Q

T/F - PDL fiber orientation changes with eruption.

A

TRUE

26
Q

In what direction does the PDL form?

A

From the CEJ apically

-Orientation is changed during eruption, based on the relative positions of the tooth and alveolar crest

27
Q

T/F - Remodeling of the PDL occurs throughout life.

A

TRUE

28
Q

T/F - Developing cells of the PDL may also prevent mineralization, preventing ankylosis.

A

TRUE

29
Q

What is the PDL composed of? 7 things.

A

Fibroblasts

Mesenchymal cells

Epithelial cells

Macrophages

Osteoblasts

Osteoclasts

Cementoblasts

30
Q

What is the width range of the PDL?

A
  1. 15 mm to 0.38 mm

* Decreases in width with age

31
Q

Primarily, the PDL is ________ fibers, supported by a non-collagenous protein matrix.

A

Collagen

*Types I, III, sometimes IV and XII

**Arranged in fibers, which are grouped into bundles

32
Q

T/F - Individual fibers can be remodeled while the overall bundle is not changes, making a very dynamic environment.

A

TRUE

33
Q

What is the main elastic fiber of the PDL?

A

OXYTALAN

Not mature elastin

34
Q

PDL fiber run _________ from cementum to the tooth apex, terminating in the neurovascular complex.

A

VERTICALLY

35
Q

The ground substance is ___% water.

A

70%

36
Q

What does the ground substance do?

A

Sequesters water via proteoglycans

Increased hydrostatic pressure, and increases its ability to absorb loads

37
Q

T/F - PDL is well vascularized.

A

TRUE

38
Q

What penetrates the cribriform plate?

A

Arterioles

Posterior teeth have more of them and they are more prevalent in the mandible as opposed to the maxilla

39
Q

Arteries occupy loose connective tissue bays in the PDL called what?

A

Interstitial areas

*Blood is critical for tissue healing/regeneration

40
Q

Where do nerves come from to the PDL?

A

Apically and thru the cribriform plate

41
Q

The nerves run _____ in relation to the tooth.

A

Axially

42
Q

Where is the greatest concentration of nerve endings?

A

At the apex

*Except at the upper incisors

43
Q

What are the 4 types of nerve endings?

A

Free - most prevalent - reach to cementum - nociceptive/mechanoreceptive

Ruffini’s corpuscles - Bulbous dendritic endings - associated with collagen fibers - mechanoreceptive

Coiled - Unknown fx

Spindle - Unknown fx

44
Q

What are the 5 PDL fiber orientations?

A

Alveolar crest - Attach just at the CEJ and run outward to attach into the alveolar socket rim

Horizontal - From cementum at a right angle to the tooth into the socket

Oblique - MOST NUMEROUS, oblique angle from cementum down to the root

Apical - Root apex to the underlying bone

Interradicular - Multi-rooted teeth - attach to interradicular septum

45
Q

What are the 5 types of gingival ligaments?

A

Transseptal - From cementum under the junctional epi, over the alveolar crest, and into cementum of an adj tooth - CAUSE OF ORTHO RELAPSE

Dentogingival - MOST NUMEROUS - Cervical cementum to lamina propria of free and attached gingiva

Alveologingival - Run from the alveolar crest to lamina propria of free and attached gingiva

Circular - Around the neck of tooth - attaches to other fibers

Dentoperiosteal - Apically from cementum to the periosteum of the outer cortical plate