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DMD2 > Periodontium histology > Flashcards

Periodontium histology Flashcards

1
Q

What are the components of the periodontium?

A

Cementum

Alveolar bone

Periodontal ligament

Lamina propria of the gingiva

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2
Q

What common illnesses are assoicated with periodontitis?

A

Alzheimer’s disease and cardiovascular disease

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3
Q

What is the periodontal ligament?

A

Specialized connective Tissue situated between cementum and alveolar bone proper

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4
Q

How thick is the periodontal ligament? What happens to its thickness with age?

A

Ranges between 0.15 and 0.38mm and is thinnest in the middle portion of the root.

Its width decreases with age

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5
Q

What kind of turnover rate does the periodontal ligament have? What does this mean?

A

Periodontal ligament has a high turnover rate.

This is why they need a large blood supply.

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6
Q

What is the embryological origin of the PDL and how does that affect the anatomy?

A

Dense fibrous connective tissue . It is derived from the dental follicle. Above the alveolar crest the periodontal ligament is continuous with the connective tissues of the gingiva; at the apical foramen it is continuous with the dental pulp .

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7
Q

What factors affect the width of the periodontal ligament?

A

Width of the periodontal space considerable
variation between teeth, according to several factors:

The functional state, non-functional and unerupted
teeth,

Permanent and deciduous teeth.

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8
Q

What are the functions of the PDL?

A

Tooth support

Shock absorption (masticatory forces)

Sensory receptor for proper jaw positioning

Nutrition (blood vessels provide essential nutrients to vitality of the PDL and cementum)

Attachment

Important for tooth eruption and drift.

Its cells form, maintain, and repair alveolar bone and cementum

Its mechanoreceptors are involved in the neurological control of mastication.

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9
Q

What fibers is the periodontal ligament made up of?

A

Collagenous (90%) [mostly type 1 - >70% and about 20% type 3]

Oxytalan

Elastin

Reticulin

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10
Q

What structure do teeth develop in?

A

Teeth are formed within the bone

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11
Q

What are the 5 groups of fibers of the periodontal ligament?

A

Dentoalveolar crest fibers

Horizontal fibers

Oblique fibers

Apical fibers (formed when the whole root is completed)

Interradicular fibers

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12
Q

What are Sharpey’s fibers?

A

Sharpey’s fibers are the fibers that go from cementum to the alveolar bone

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13
Q

What are the types of gingival ligament fibers?

A

Dentogingival: most numerous; cervical cementum to f/a gingiva

Alveologingival: bone of the alveolar crest to f/a gingiva

Circular: around neck of teeth, free gingiva

Dentoperiosteal: runs apically from the cementum over the outer cortical plate to alv. process or vestibule (muscle) or floor of mouth

Transseptal: cementum between adjacent teeth, over the alveolar crest

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14
Q

Where does the dentogingival fibers of the PDLigament go?

A

Cervical cementum to the free and attached gingiva

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15
Q

Where does the alvelogingival fibers of the PDLigament go?

A

Bone to to the free and attached gingiva

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16
Q

Where are the circular fibers of the PDL locaed?

A

Around neck of the teeth and free gingiva

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17
Q

What happens when the PDL is destroyed?

A

Destruction of the PDL leads to loose and sometimes disconnected teeth

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18
Q

Where are principal fibers of the PDL smallest?

A

At the cementum (Sharpey’s fibers)

19
Q

What is teh function of hyaluronate GAG?

A

Fiber orientation and calcification of the fibers.

Water binding and exchange, control of collagen fibrillogenesis and
fiber orientation

20
Q

Which part of the tooth has a large number of stem cells?

A

Dental pulp has lots of stem cells

21
Q

What cells of the PDL do most of the synthesis?

A

Fibroblasts and fibroclasts

Cementoblasts and cementoclasts

Osteoblasts and osteoclasts

Progenitor cells

22
Q

What do fibroblasts do?

A

Regenerate tooth support apparatus

Adaptive response to mechanical loading

Protein synthesis and secretion

secrete
metalloproteinases-1 (which
degrades extracellular matrix collagen at physiological conditions )

Secrete Tissue Inhibitors of MetalloProteinases - 1 (TIMPs)

Collagenase production and phagocytosis

Have cilia and many intercellular contacts, the cilium differs from those seen in other cell types

23
Q

What structures join fibroblasts to each other?

A

Gap junctions (for cell communication and

24
Q

What motility features do fibroblasts have?

A

They have chemotactic abilities and motile-contractile features

25
Q

What are cementoblasts?

A

Cement-forming cells

Cuboidal cells

Protein synthesis and secretion

26
Q

What do osteoblasts do?

A

Form bone

Protein synthesis and secretion

27
Q

What do osteoblasts look like on histology?

A

Cuboidal cells with basophilic cytoplasm

Desmosomes and tight junctions, some tight junctions with osteocytes

28
Q

Where do osteoclasts and cementoclasts arise from?

A

From blood cells such as macrophages

29
Q

What do epithelial cell rests of malassaez do?

A

Chrnic inflammation

Direct cellular events during cementogenesis

Inhibit cementogenesis in mature teeth

Capable of phagocytosing collagen and synthesizing metalloproteinases and prostaglandins

30
Q

How are cells lost and gained in the PDL?

A

Periodontal fibroblasts comprise a renewal cell system
– balance between newly generated cells and cells lost by apoptosis and migration out of the tissue.

Progenitor cell population are located adjacent to the blood vessels near the surface of the alveolar bone .

The rate of cell generation (mitotic index ) is modest (0,5 – 3%)

31
Q

Where does the PDL get its blood supply?

A

From perforating arteries (cribiform plate of the bundle bone)

The small capillaries derive from the superior and inferior alveolar arteries

The blood supply is rich because the PDL has a very high turnover rate

Posterior blood supply is more prominent than he anterior blood supply.

Mandibular blood supply is more prominent than the maxillary.

32
Q

What kind of nerve endings are in the PDL?

A

Nerve endings are mechanosensors which respond to pressure

33
Q

What are the types of bone seen in the oral cavity?

A

Developmentally:

Endochondral bone

Intramembranous bone

Histologically:

Compact bone

Cancellous bone

Lamellar bone

Woven bone

34
Q

Where are bones located relative to the teeth? (Classification based on location)

A

Internally: Thin layer of compact bone lines the tooth socket and gives attachment to the principal fibers of the periodontal ligament

Externally: On the buccal/labial and lingual/palatal surfaces are thicker layers of compact bone, forming the external and internal alveolar plates

35
Q

What is bundle bone?

A

Bone that is perforated by many foramina that transmit nerves and vessels

36
Q

What does bundle bone look like radiographically?

A

Radiodense because inreased mineral content around the fiber bundles.

The bundle bone is the lamina durea the lining of the alveolus is fairly smooth in the young but rougher in the adults.

37
Q

Where is the alveolar crest located?

A

It is found 1.5 - 2mm below the level of the CEJ.

38
Q

What does it mean if the line connecting the CEJ of adjacent teeth is not parallel to the alveolar crest?

A

Then there is a high probability of periodontal disease

39
Q

What is bone remodelling?

A

Bone remodeling involves independent
sites of resorption and formation that
change the size and shape of bone

40
Q

What are the stages of bone remodelling?

A

Activation

Resorption (osteoclasts)

Reversal

Formation (osteoblasts)

Termination

41
Q

How does bone resorption take place?

A

Ruffled border with microenvironment of low pH and lysosomal enzymes is formed which breaks down the bone.

42
Q

What is osseointegration?

A

Integration of structures in the bone and soft tisse to the prosthetics and teeth (as seen in dental implants).

43
Q

What clinical consideration does the remodelling of bone have on movement of teeth?

A

This process can occur during orthodontic
movement of teeth. Bone is resorbed on the side of
pressure and opposed on the site of tension.

44
Q

What happens at tensile site during orthodontic treatment?

A

Dilatation of blood vessels

More O2 demand

Active metabolism

New bone formation

DMD2 (89 decks)

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