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Oral Sciences > Unit 4a - PDL > Flashcards

Unit 4a - PDL Flashcards

1
Q

Where do the PDLs attach she the tooth begins active eruption?

A

Some insert one end into the developing cementum at the most cervical part
The other end reaches out to the direction of the developing alveolar bone
The ends of the fivers that insert into the bone and the cementum are called sharpeys fibers

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2
Q

What is happening perpendicular to the cementum of the tooth root and the developing alveolar bone?

A

Fibroblasts arrange themselves in rows
Short collagen finders assume the same orientation
Turnover of these collagen fibers is rapid especially in the most apical areas
They are continually renewed as further development of the root and PDL is established
As the root forms, new and developing small fibers continue to form apically and orient themselves

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3
Q

What is the intermediate plexus

A

More coronally (toward the cervical root) the collagen fibers grow longer and shift to meet their counterparts (from the alveolar bone side), forming the intermediate plexus

During development, the tooth root fibers develop and grow toward the bone side fibers
They meet approximately half way between tooth and bone
These connections are established in an intermediate plexus

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4
Q

What are principle fiber bundles?

A

Groups of fibers that are oriented in a similar direction and locations

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5
Q

What is the orientation of the PDL fibers during development?

A

All fiber bundles start with an oblique orientation, with bony ends coronal to cementum ends.
As eruption occurs and the tooth reaches a final position, the fiber groups are established
The apical group is the last group to be formed
The alveolar crest fibers orientation will end up with the tooth ends coronal to the bone ends

After teeth are on function for a time, the fiber bundles will mature and thicken

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6
Q

What are the groups of fiber bundles that make up the principle fiber bundles

A 
Apical
Oblique
Horizontal
Alveolar crest
Interradicular
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7
Q

What is the location and function of the alveolar crest group

A

Attached to cementum just below CEJ and runs inferior and outward direction to insert into alveolar crest of alveolar bone proper

Function is to resist tilting, intrusive, extrusive, and rotational forces

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8
Q

What cells form the PDL

A

Cells of the dental sac (follicle)
At the same time of embryonic development of the enamel organ, mesenchymal cells differentiate into fibroblasts and synthesize collagen fibres
The initial fibers lie somewhat parallel to the outer surface of the enamel organ
Formation begin with active eruption

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9
Q

What is the location and function of the horizontal group of fibers

A

Just apical to alveolar crest group and runs 90degrees to the long axis of the tooth from cementum to the alveolar bone proper
Just inferior to the alveolar crest

Function is to resist tilting forces and rotational forces

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10
Q

What is the location and function of the oblique group of fibers

A

Runs from cementum in oblique direction to insert into alveolar bone proper more coronally

Function is to resist intrusive forces and rotational forces

This group is the most numerous on roots

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11
Q

What is the location and function of the apical group of fibers

A

Radiates from cementum around apex of the root to surrounding alveolar bone proper, forming base of alveolus

Function is to resist extrusive forces and rotational forces

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12
Q

What is the location and function of the Interradicular group

A

Runs from cementum of one root to the cementum of another root superficial to Interradicular septum and this has no bony attachment superficial to Interradicular septum

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13
Q

What fibers make up the gingival fiber unit?

A

Free and attached gingival fibers; from cementum(tooth) to gingiva
Alveogingival; from alveolar crest to gingiva
Circumferential; circular-circles the tooth in the attached/free gingiva (connective tissue)
Transseptal; included in this group though cementum to cementum attachment

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14
Q

What are the main functions of the gingival fiber group?

A

To resist gingival displacement
Supper the JE attachment

The transseptal fibers main function is to resist drifting of adjacent teeth

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15
Q

What other fibers are present in the PDL space other than principle fiber bundles?

A

Oxytalan fibers
Small thin fibers with no distinct orientation; more longitudinal to PDL fibers
Interlace with collagen and BV walls; possible support function
Variant of the elastic-smaller

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16
Q

What cellular elements are present in the PDL space

A 
Fibroblasts
Osteoblasts
Cementoblasts
Undifferentiated mesenchymal cells
Macrophages
Lymphocytes
Epithelial Cells

It is probable that some of these cells functions in forming as well as destroying collagen fibers as need arises

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17
Q

What is the epithelial cell rests of malassez?

A

Recall from the formation of the root (HERS)?
Small group of chain of eptithelial cells
Remnants of down growth of epithelium during embryonic phase that outlines the roots

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18
Q

What components make up the interstitial spaces around the PDL

A

Ground substance: product of cells and from capillaries
Like that in other CT of the body: 70% water, glycoproteins, and proteoglycans

Spaces for neural and BVs and lymph: compress during mastication

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19
Q

Recall the blood and lymph supply to PDL

Specific names

A

Blood vessels-PSA, ASA, inferior alveolar, and facial

20
Q

What are the two types of PDL?

A

Sensory - V2&V3 branches

Autonomic - sympathetic - function is to regulate blood flow

21
Q

What are other components in PDL?

A

Cementiles - mini bodies of cementum

Free or attached

Cementoblasts on surface

Undifferentiated mesenchymal

22
Q

Who do the PDL attach?

A

Via sharpey’s fibers in the cementum
Terminal ends of fiber bundles inserted into calcifying matrix (cementum and bone)
Insertion occurs during apposition and mineralization

23
Q

What is the function of the PDL

A

Physical
Sensory
Nutritive
Formative

Fill in more details - the how’s!

24
Q

Can PDL repair itself?

A

Localized destruction may be repaired by new tissue regeneration ‘as long as the irritant is removed’
Localized detachment can reattach if cellular structures are vital

25
Q

What happens in the early stages in the development of the alveolar process?

A

When the teeth are in the early stages of development, intramembranous ossification is taking place within the jaws
Both the primary and secondary tooth germs are located in a common groove in the bone
The outer edges of this groove curve gently inward, partially surrounding the tooth in a delicate network of bone

26
Q

What happens on the later stages of development of the alveolar process?

A

Later in fetal life, small bony septae form between the different primary teeth - leaving tooth germs with its permanent successor in a separate bony compartment known as a crypt. This wall and crypt will be broken down with the successor tooth erupts.

Most home deposition takes place at the rim of the bony groove, growing occlusally along with the erupting tooth (this way the height of the alveolar bone increases)

Alveolar bone develops from cells of the dental sac as is the perio ligament. It is deposited around the developing ligament fiber bundles reducing space between the crypt walls and the tooth dimension of the PDL

27
Q

What are the functions of the alveolar bone?

A

To provide biomechanical support and protection for tissues surrounding it

To serve as a reservoir for calcium and phosphorus ions for the body (constant remodelling)

28
Q

What are the types of bone?

A

Compact:
Lamellae *structure = layers
Location is outer wall of bone *recall alveolar bone locations

Trabecular/spongy (cancellous):
Plates of bone with bone marrow (supporting bone)
Thickness of trabeculae will vary with function

Alveolar bone proper:
Bony socket wall *other names

29
Q

What is the composition of alveolar bone?

A

Inorganic-mineralized component =60%
Organic-no mineralized component=40%

Varies by +- 5% depending on individual or text!

30
Q

What covers the alveolar process?

A

Periosteum:
Outer layer on bone = dense fibrous connective tissue
Osteoblasts reside and function
Sharpeys fibers insert and connect to osteoid/bone

Endosteum:
Inner surface of bone next to bone marrow/lines haversian & volkmann’s canals
Less dense fibrous connective tissue *delicate CT

31
Q

What are the cells related to bone?

A

Osteoblasts - are from mesenchymal cells in the area - they synthesize bone protein and also mineralized the osteoid matrix
Osteoclasts - remove bone to relieve compression. Derived from monocytes in the blood.
Osteocytes

32
Q

Describe the bone matrix

A

Fibrous, mainly collagen fibers (like other CT)
Ground substance
Crystalline part - hydroxyapatite (calcium phosphate salts)
Together these form first nonmineralized osteoid, then minerals are deposited and they mature (increase in size and hardness)
Level of minerals are most like that in cementum?

33
Q

Describe the structure of bone

A

Lamellae - periosteal lamellae cover the surface of the mandible
Lacunae - contain osteocytes and surround the Haversian canals
Canaliculi - channels connecting lacunae
Haversian system - contain blood vessels, Lamellae arranged in concentric circles around central canal
Volkmann’s canals - interconnect the haversian system, canals through which bv’s pass into bone from outside or from within marrow cavities

34
Q

What are other names for alveolar bone proper

A

Cribiform, lamina dura, bundle bone

Bundle bone = thickened alveolar bone proper - fiber bundles attached

35
Q

What types of bone are considered supporting bone?

A

Cortical bone - facial and lingual

Spongy - trabeculae

36
Q

How does healthy periodontist appear radiographically?

A

Lamina firs appears as a dense, radiopaque line around the roots of the alveolar crest:
Anterior: pointed, sharp, radiopaque
Posterior: follows and flat, smooth, line that is parallel to a line between adjacent CEJs
The height of normal crest all bone is within 2mm of the CEJ

The PDL space appears thin, continuous, regular radiolucent line of uniform thickness
May have altered bone height (loss of crestal bone height) and still have healthy bone in remaining bone, characterized by a crestal bone that appears dense (highly radiopaque)

You can only see proximal and crestal bone on radiographs and not radicular bone!

37
Q

What is apposition?

A

Osteoblasts produce nonmineralized matrix = osteoid that later calcifies

This occurs in layers
As one osteoid layer is calcifying, the next layer of osteoid is well under way

38
Q

What is resorption?

A

This is the process of removal of mineral AND organic matrix by osteoclasts
It is a natural process unless stress and disease occur, then it may cause an imbalance of the amount of bone being formed versus that being resorbed!

39
Q

What is demineralization?

A

It is the removal of mineral matrix only. It is not a natural process.

40
Q

What is meant by balance when it comes to alveolar bone?

A

This is the intermittent and constant change throughout life and the amount will vary with growth and function.

Situations will change the amount of formation and resorption:

pressure: resorption
tension: apposition

41
Q

What are the responses of alveolar bone to trauma, pressure and disease?

A

Normal forces = maintenance of density and size

Trauma (ie. Occlusal) = resorption of alveolar bone

Disease - PDL loss and resorption of alveolar crest/visible on radiograph (with apical migration of JE)

42
Q

What are the clinical significance of alveolar bone levels?

A

Contour of bone effects gingival contour:
Good indicator of periodontal health
Depends on teeth alignment and bone levels

Position:
Where gingival margin rests on teeth - recession
Affects gingival position & *JE position
Position is described relative to where the gingival margin rests on teeth and where the junction all epithelium is.

43
Q

What clinical changes do we see with disease?

A

Loss of interdental papilla
Increase in pocket depth
Root exposure - recession (sensitivity)
Mobility, drifting, tooth loss

All influence the shape and presence of alveolar bone!

44
Q

What clinical signs do we see with age? Histological my only.

A

Osteoporotic - jagged walls
Bone loss with fewer fiber bundles attached
Fewer viable cells and increase in fat cells

45
Q

What is the normal position of healthy alveolar bone?

A

1-2 mm apical to JE/CEJ

CEJ is landmark for measurement of alveolar bone levels
Radiographic - good to view proximal bone (height and quality)

Oral Sciences (8 decks)

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