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BDS2; Integrated Clinical Practice > ICP L24: Periodontal tissues in human health and disease > Flashcards

ICP L24: Periodontal tissues in human health and disease Flashcards

1
Q

What is the periodontium

A

Collective term describing tooth supporting tissues including

  • root cementum
  • periodontal ligament
  • alveolar bone
  • gingiva

These tissues develop and function as a unit along with the formation of tooth roots and tooth eruption

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2
Q

When does tooth development start

A

Around 6th week where there is thickening of the oral epithelium and underlying mesenchyme interaction

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3
Q

What is the tooth germ

A

An aggregation of cells derived from the ectoderm of the first pharyngeal arch and the ectomesenchyme of the neural crest

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4
Q

What is the tooth germ organised into

A
  1. Enamel orgam = enamel and primary epithelial attachment (periodontal tissue)
  2. Dental papilla = pulp and dentine
  3. Dental follicle = cementum, periodontal ligament, alveolar bone (is most of the periodontal tissue)
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5
Q

Describe the macroscopic anatomy of the gingiva

A

The part of the oral mucosa covering the tooth-bearing part of the alveolar bone and the cervical neck of the tooth - it is divided anatomically into attached, marginal and interdental gingiva

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6
Q

What is the purpose of the gingiva

A

It is a major peripheral defence against microbial infections and mechanical trauma - it has sensory function and is well innervated with pain, touch and temperature receptors

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7
Q

Where is the free gingiva

A

Between gingival margin and gingival groove (before the attached gingiva) and is delicately attached to the tooth

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8
Q

Where is the attached gingiva

A

Between gingival groove and muco-gingival junction: It is firm, resilient and tightly bound to the underlying periosteum of alveolar bone

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9
Q

Where is the alveolar mucosa

A

Above the muck-gingival junction

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10
Q

Describe the macroscopic anatomy of the attached gingiva

A
  • It is covered by keratinised epithelium
  • Width is greatest over the buccal surface of maxillary incisors and narrowest over the buccal surfaces of mandibular premolars
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11
Q

Describe the macroscopic anatomy of the free gingiva

A

It covers 1-1.5mm of tooth surface and surrounds the cervical part of teeth and is separated from the teeth by the gingival sulcus

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12
Q

What is the gingival sulcus

A

Shallow crevice around tooth bounded on one side by the sulcular epithelium and the other by the tooth - the coronal extent of the gingival sulcus is the gingival margin (V-shaped)

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13
Q

What is the gingival zenit

A

The most apical point of the marginal gingival scallop

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14
Q

What is the biological width of gingiva

A

The natural seal that develops around teeth and protects the alveolar bone from infection and disease (includes epithelial attachment and CT attachment)

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15
Q

What is the supracrestal tissue attachment

A

This term replaces biological width and it is the attached tissues composed of junctional epithelium and supracrestal connective tissue

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16
Q

What is interdental gingiva

A

Gingiva occupying gingival embrasure which is the inter proximal space beneath the area of tooth contact (= pyramidal/col shaped) The shape of this gingiva depends on the contact point between two teeth

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17
Q

What is the thin scalloped periodontal phenotype

A

This gingival phenotype is associated with

  1. Slender triangular shaped crowns
  2. Subtle cervical convexity
  3. Interproximal contacts close to the incisal edge
  4. Narrow zone of keratinised tissue
  5. Clear thin, delicate gingiva close to alveolar bone
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18
Q

What is the thick scalloped periodontal phenotype

A

This gingival phenotype is associated with

  1. Clear thick fibrotic gingiva
  2. Slender teeth
  3. Narrow zone of keratinised tissue
  4. High gingival scallop
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19
Q

What is the flat thick periodontal phenotype

A

This gingival phenotype is associated with

  1. More square shaped tooth crowns
  2. Pronounced cervical convexity
  3. Large inter proximal contact apically
  4. Broad zone of keratinised tissue
  5. Clear thick, fibrotic gingiva
  6. Comparatively thick alveolar bone
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20
Q

Where is a common area for physiological/racial gingival pigmentation

A

Attached gingiva

  • Multifocal/diffuse melanin pigmentation
  • Due to greater melanocyte activity (not more melanocytes)
  • Asian, African, Mediterranean
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21
Q

What is the oral gingival epithelium

A

Extends from mucogingival junction to the tip of the gingival crest and is subdivided into the free marginal and attached gingiva

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22
Q

Describe microscopy of the gingival epithelium

A
  • Keratinised, stratified, squamous epithelium
  • 0.2 - 0.3mm thickness
  • Originates from oral mucosa
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23
Q

Outline the layers of the gingival epithelium

A

Stratam basale (facing CT)
Stratum spinousum
Stratum granulosum
Stratum corneal (outermost)

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24
Q

What are Retentions ridges

A

These are tags formed in the stratum basal layer of gingival epithelium which permit interchange of nutrients from CT to basal cells - this increases surface contact between the CT and gingival epithelium

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25
Q

What are the principal cells in the oral gingival epithelium

A
  1. Keratinocytes
  2. Langerhans cells (dendritic cells at basal level belong to mononeucleocyte system)
  3. Melanocytes
  4. Merkels cells
  5. Inflammatory cells
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26
Q

What is the oral sulcular epithelium

A

Lines the gingival sulcus and extends from tip of the gingival crest to the most coronal portion of the junctional epithelium

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27
Q

Describe the microscopy of the oral sulcular epithelium

A
  • Non-keratinised, stratified squamous epithelium
  • No rete pegs
  • Acts as semipermeable membrane
  • Originates from the oral mucosa
  • Cell layers similar to the oral gingival epithelium
  • Forms gingival crevice/sulcus

Gingival sulcus

  1. Histological depth = 0-0.5mm
  2. Clinical depth = 0.5-3mm
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28
Q

What is the junctional epithelium

A

It forms the attachment of the gingival to the tooth via hemidesmosomes

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29
Q

Describe the microscopy of the junctional epithelium

A
  • Non-keratinised, stratified squamous epithelium
  • Continuous with oral sulcular epithelium
  • Wider spaces between cells
  • No rete pegs
  • Originates from the enamel organ (rest is from dental follicle)
  • Provides attachment to tooth surface via hemidesmosomes
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30
Q

What is the role of the junctional epithelium

A
  • It forms the attachment of the gingiva to the tooth via hemidesmosomes
  • Provides vehicle for the bidirectional movement of substances between gingival connective tissue and the oral cavity
  • Provides an epithelial barrier against plaque bacteria
31
Q

What is the role of gingival fibres

A

To reinforce the attachment of junctional epithelium to the tooth - these brace the marginal gingiva against the tooth surface

32
Q

What is the dent-gingival unit

A

Junctional epithelium and gingival fibres

33
Q

What is the connective tissue part of the gingiva

A

Fibrous connective tissue which originates from oral mucosa and dental follicle = lamina propria

34
Q

What is the role of connective tissue in the gingiva

A
  • It is highly vascularised (gingival plexus contained)
  • Protects the tooth surface and alveolar bone from external oral environment
  • Provides support to the epithelial tissues
35
Q

What are the layers of the connective tissue in the gingiva

A
  1. Papillary later = papillary projections between the epithelial rete pegs
  2. Reticular layer = contiguous with the periosteum
36
Q

Describe the cellular and matrix components of connective tissue in the gingiva

A

Fibroblasts = major cellular components synthesising collagen, elastic fibres, glycoproteins, glycosaminoglycans and regulate collagen degradation
Immune cells

Ground amorphous substance: fills the space between cells and fibres
Fibres: Collagen type I and non-collagenic fibres

37
Q

What are the dento-gingival fibres in connective tissue

A
  • Project from cementum in a fan like pattern into the free gingival tissue of facial, lingual and inter proximal surfaces
  • Provide gingival support
38
Q

What are the alveoli-gingival fibres in connective tissue

A

Starting from the periosteum covering the alveolar crest these fibres project coronally into the attached gingiva and attach gingiva to the bone

39
Q

What are the dento-periosteal fibres in connective tissue

A

These are in the same part of the cementum as dent-gingival fibres but run apically over the vestibular and lingual bone crest and terminate in the attached gingiva

It anchors the tooth to bone and protects the PDL

40
Q

What are the circular fibres in connective tissue

A

These run in the marginal and interdental gingiva and encircle each tooth in a cuff/ring to maintain contour and position of free marginal gingiva

41
Q

What are the trans-septal fibres in connective tissue

A

These extend between supra-alveolar cementum of adjacent teeth and run straight across the interdental septum embedded in the cementum of adjacent teeth - they support interdental gingiva and secure the positions of adjacent teeth to protect inter proximal bone

42
Q

What is gingival crevicular fluid

A

Serum transudate/inflammatory exudate that is found in the crevice arising from the gingival plexus of blood vessels in the gingival corium subjacent to the epithelium lining of the dentogingival space

43
Q

What is cementum

A

Avascular mineralised tissue covering the root surface beginning at the cervical portion of the tooth at the CEJ and continuing to the apex - this is less hard than dentine and very permeable

44
Q

What is the role of cementum

A
  • Anchorage: medium for attachment to the collagen fibres of PDL
  • Repair/resorption: continuous deposition this it repairs the damage
  • Protection (fluoride): seal for open dentinal tubules
45
Q

Describe the three types of macroscopic anatomy of the CEJ

A
  1. Cementum overlaps enamel
  2. Cementum and enamel are continuous edge-to-edge
  3. There is a gap between cementum and enamel leaving exposed dentine
46
Q

What are the cell types on cementum and what are their functions

A
  1. Cementoblasts = mesenchymal cells synthesising collagen and protein polysaccharides making up cementum organic matrix - these line the root surface
  2. Cementocytes = spider shaped cells occurring in the formation of cellular cementum when cementoblasts become trapped in their own matrix
  3. Cementoclasts = multinucleate giant cells which resorb and repair the cementum
47
Q

What is in the anorganic and organic components of cementum

A

Anorganic = calcium phosphate HA, trace elements and fluoride

Organic = Type I and III collagen embedded in inter fibrillar ground substance of glycoproteins; non-collagenous proteins

48
Q

What are the extrinsic fibres of cementum

A

Principal fibres = Sharpey’s fibres which are continuous with principal fibres of the periodontal ligament (produced by fibroblasts and so are extrinsic to the cementum)

These are oriented perpendicularly to the cementum and are important in tooth anchorage

49
Q

What are the intrinsic fibres of cementum

A

Fibres produced by cementoblasts which are oriented parallel to the cementum

The fibres are dense and irregularly arranged in the cementum matrix and located at the sites undergoing repair following surface resorption (no role in tooth anchorage)

50
Q

What are the 4 main types of cementum and where are they found

A
  1. Acellular extrinsic fiber cementum (AEFC) = coronal 2/3 root: collagen fibres and glycosaminoglycans produced by cementoblasts and fibroblasts, densely packed bundles of Sharpey’s fibres in a non-cellular ground substance with the function of tooth anchorage
  2. Cellular mixed stratified cementum (CMSC) = apical 1/3 of root and furcation area: Sharpey’s and intrinsic fibres with irregularly distributed cells. Lacunae with canaliculi are present which reside in cementocytes
  3. Cellular intrinsic fiber cementum (CIFC) = furcations and apical root: Component of CMSC, cells but no collagen fibres, participates in repairing resorbed roots
  4. Acellular afibrillar cementum (ACC) = coronal cementum over enamel at CEJ (rare): Contains neither cells nor extrinsic/intrinsic collagen fibres
51
Q

What happens to cementum with age

A
  • Surface becomes more irregular due to calcification of fiber bundles where they attach to cementum
  • Cemental width increases (greater apically than lingually)
  • Apical enlargement can cause apical foramen obstruction
52
Q

What is the periodontal ligament and what roles does it have

A

Soft specialised connective tissue between the cementum and bone socket wall extending coronally up to the most apical part of the connective tissue of the gingiva

Roles

  • supportive
  • sensory/proprioception
  • formative
  • protective
  • regeneration/wound healing
  • nutritive
53
Q

What cells are found in the periodontal ligament

A

Fibroblasts, cementoblasts, osteoblasts, osteoclasts, odontoblasts, epithelial cells, epithelial cell rests of Malassez, nerve cells, immune cells, undifferentiated mesenchymal cells

54
Q

How are fibroblasts distributed within the periodontal ligament and what is their role

A

They are the most predominant cell type and are arranged regularly throughout the ligament oriented with their long axis parallel to the direction of collagen fibres

They synthesise and shape the proteins of the extracellular matrix in which collagen fibrils form bundles that insert into cementum and bone as Sharpey’s fibres

55
Q

What are epithelial cell rests of Malassez and what is their role

A

They are discrete clusters of residual cells from Hertwig’s epithelial root sheath (HERS) that don’t disappear

  1. Maintain periodontal ligament homeostasis to prevent ankylosis
  2. Maintain periodontal ligament space
  3. Prevent root resorption
  4. Serve as a target during periodontal ligament innervation
  5. Contribute to cementum repair
56
Q

What are the 5 types of principal fibres in the periodontal ligament and what are the roles of each of these

A
  1. Alveolar crest fibres = extend obliquely from cementum beneath CEJ to alveolar crest: resists tilting, intrusive, extrusive and rotational forces
  2. Horizontal fibres =attach to the cementum apical to alveolar crest fibres and run perpendicularly from the root of the tooth to the alveolar bone - pass from their cement attachment directly across the PDL space to become inserted in alveolar process as Sharpey’s fibres: resist horizontal and tipping forces
  3. Oblique fibres = from cementum in an oblique direction to insert into bone coronally: resist vertical and intrusive forces
  4. Apical fibres = radiate from cementum around apex of root to bone, forming base of the socket/alveolus: resists forces of lunation, prevent tooth tipping and protect blood and lymph vessels and nerves traversing PDL space at root apex (not in incompletely formed roots)
  5. Inter-radicular fibres = between the roots of multi-rooted teeth extending from radicular cementum to inter-radicular alveolar bone: resists tooth tipping, torquing and luxation
57
Q

What is the alveolar bone

A

Specialised bone structure containing sockets of the teeth and supporting the teeth (develops from dental follicle). It consists of

  • alveolar process/ supporting alveolar bone (max/mand)
  • alveolar bone proper (bundle bone and Sharpey’s fibres)
58
Q

What is the function of alveolar bone

A
  1. Anchorage
  2. Protection and support for teeth
  3. Bone synthesis
  4. Absorbs and distributes forces
59
Q

Describe the cortical bone in the alveolar process

A

It extends on the lingual/palatal and buccal side

  • it is thicker in the mandible than maxilla
  • greater lingual/palatally than buccally
  • fundamental units are osteons (cylindrical structures made of concentric lamellae organised around Harversian canals)
60
Q

Describe the cancellous bone in the alveolar process

A

Spongey cancellous bone has a honeycomb structure

- network of highly connected trabecular containing bone marrow

61
Q

What is the alveolar bone proper/bundle bone

A

Continuation of the cortical plate lining the tooth socket = cribriform plate which has a sieve-like appearance produced by numerous vascular canals

  • surrounds the root and gives attachment to principal fibres of PDL with the fibres arranged parallel to the socket wall
  • it is specialised compact bone composed of bundle bone (numbers Sharpey’s fibres passing into it from PDL) and Haversian bone
  • it has fewer and less mature intrinsic collagen fibrils in the intercellular substance than the mature lamellar bone but more calcium salts causing it to be more radiopaque (lamina dura)
62
Q

What is periodontal disease

A

Chronic multifactorial inflammatory disease initiated by bacterial microorganisms characterised by a severe chronic inflammation that leads to progressive destruction of the tooth supporting apparatus, tooth loss and eventually to masticatory dysfunction

A pathogenic biofilm is necessary but it is the inflammatory-immune response which accounts for periodontal tissue damage

63
Q

What is plaque induced gingivitis

A

Inflammation of the gums due to plaque accumulation causing: erythema, oedema, tenderness, enlargement, swelling, redness and bleeding on probing

This is reversible as there is no bone loss

64
Q

What is periodontitis

A

Supra and subgingival plaque/calculs accumulation leading to: erythema, oedema, tenderness, enlargement, welling, redness, suppuration (pus from sulcus), tooth mobility, gum recession, halitosis, pocket formation and bleeding on probing

This is irreversible as there is loss of periodontal attachment

65
Q

What is the difference between a periodontal pocket and a gingival pocket

A

Periodontal pocket = A pathologically deepened gingival sulcus around a tooth at the gingival margin with destruction of supporting periodontal tissue (suprabony = horizontal loss or intrabony = vertical loss)

Gingival pocket (pseudopockets) = Formed by gingival enlargement without destruction of underlying tissues - the sulcus deepens due to increased bulk of gingiva

66
Q

Describe the progression of gingival and periodontal inflammation via the 4 stages

A
  1. Initial lesion = clinically health gingival tissue, elevated vascular permeability, increased GCF flowing out of sulcus, migration of leukocytes and neutrophils through gingival CT, JE and sulcus
  2. Early lesion = early gingivitis with increased vascular permeability, vasodilation and GCF flow, large numbers of leukocytes (neutrophils and lymphocytes), collagen destruction and proliferation of JE and sulcular epithelium into collagen-depleted areas
  3. Established lesion = chronic gingivitis with dense inflammatory infiltrate (plasma cells, lymphocytes, neutrophils), elevated release of MMPs and lysosomal contents from neutrophils, JE is not closest attached to tooth and a pocket epithelium has formed which contains many neutrophils
  4. Advanced lesion = transition from gingivitis to periodontitis, pocket deepens forming an anaerobic niche filled with neutrophils and dense inflammatory infiltrate in the CT (primary plasma cells): Apical margin of JE preserves intact epithelial barrier, continued collagen breakdown leading to collagen depleted connective tissue and osteoclastic resorption of alveolar bone
67
Q

What are the key mediators orchestrating the host response in the progression of gingival and periodontal inflammation

A
  1. Cytokines
  2. Prostaglandins
  3. Matrix metalloproteinases (MMPs)
68
Q

What are cytokines

A

Soluble proteins secreted by cells involved in innate and adaptive immune response (neutrophils, macrophages, lymphocytes) and resident cells in the periodontium (fibroblasts and epithelial cells)

69
Q

What is the role of cytokines

A
  • Messenger molecules which bind to specific receptors on target cells that initiate intracellular signalling cascades to produce proteins altering cell behaviour
  • They act locally and are effective in low concentrations
  • Initiate and maintain immune and inflammatory responses
  • Regulate growth and differentiation of cells
70
Q

What are prostaglandins

A

Group of lipid compounds derived from arachidonic acid which is metabolised by COX1/2 to generate PGs, thromboxane and prostaglandins

71
Q

What is the role of prostaglandins

A
  • Important mediators of inflammation especially PGE2

- Produced mainly by macrophages and fibroblasts

72
Q

What is PGE2

A

Potent vasodilator, inducing cytokine production by various cells, acts on fibroblasts and osteoclasts to induce production of MMPs for tissue turnover/destruction in gingivitis and periodontitis

73
Q

What are matrix metalloproteinases (MMPs)

A

Family of proteolytic enzymes responsible for remodelling and degradation of the matrix components

  • they have regulatory properties
  • produced by neutrophils, macrophages, fibroblasts, epithelial cells, osteoblasts, osteoclasts

BDS2; Integrated Clinical Practice (25 decks)

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