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Craniofacial and Tooth Biology > 24. Gingiva and GDJ > Flashcards

24. Gingiva and GDJ Flashcards

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1
Q

Define ‘gingiva’

A

part of oral mucosa that surrounds and is attached to teeth and alveolar bone
- continuum with oral mucosa and periodontal ligament

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2
Q

What creates the DGJ?

A

tooth eruption

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3
Q

How does tooth eruption create a DGJ?

A
  • during tooth eruption, reduced enamel epithelium fuses with oral epithelium to establish dentogingival junction
  • tooth approaches oral epithelium, only a thin layer of connective tissue separates the REE from oral epithelium (stratified squamous)
  • fusion of REE with OE and degeneration of central epithelial cells
  • epithelial continuity at all times (no connective tissue exposure - no bleeding)
  • tooth erupted and DGJ formed - junctional epithelium are for tooth attachment
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4
Q

Immediately after tooth eruption, junctional epithelium is entirely …

A
  • reduced enamel epithelium
  • not keratinised and attaches firminly to enamel of teeth
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5
Q

What happens to epithelium some time after tooth eruption?

A
  • gingival epithelium (is stratified, keratinised) appears to overgrow and replace REE
  • sulcular epithelium then (statified, non keratinised)
  • switch from gingival to sulcular keratinocyte identity and stratification of REE cells and rete peg formation
  • development of sulcus induced by masticatory forces acting on gingiva
  • base of sulcus is same level as free gingival groove
  • junctional epithelium still appears like REE
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6
Q

What happens to gingival epithelium 2-3 years after tooth eruption?

A
  • gingival ep appears to have completely replaced REE (based on epithelial morphology e.g stratified rete pegs
  • small epithelial tag from REE remains - cell remnants and primary enamel cuticle (Nasmyth’s membrane)
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7
Q

Are junctional and gingival epithelial cells the same?

A
  • molecular markers indicate no
  • REE can become stratified and develop rete pegs
  • stem cells can reform JE - tooth attachment restored after gingivectomy and gingival tissue grafting
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8
Q

Origin of junctional epithelium

A

-amelotin and odontogenic ameloblast-associated
- normally expressed by maturation stage ameloblasts - forming REE
- expression in internal basal lamina and junctional epithelial cells suggests junctional epithelium is derived from REE

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9
Q

How is there tight attachments of junctional epithelium to teeth?

A
  • epithelial cells secrete primary enamel cuticle - internal basal lamina - onto enamel surface where it bonds with enamel proteins
  • cells attach via hemidesmosomes
  • external basal lamina (typical composition) attaches to lamina propria
  • very strong epithelial attachment to tooth
  • once lost in periodontal disease, it is difficult to regenerate
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10
Q

Junctional epithelium is … due to …

A
  • permeable
  • due to reduced number of desmosomes and larger intercellular spaces
  • allows passage of gingival crevicular fluid and defence cells into sulcus
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11
Q

Gingival crevicular fluid contains …

A
  • immunoglobulin molecules
  • complement factors
  • macrophages
  • cytokines and metalloproteases (during infection)
  • desquamated sulcular and junctional epithelial cells (around 5-6 days turnover)
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12
Q

What is the function of GCF?

A
  • defence against pathogens
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13
Q

What if GCF is overproduced?

A
  • tissue damage through overproduction of MMPs
  • these degrade extracellular matrix and collagen fibres of gingival connective tissue
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14
Q

Composition of GCF can be measured and is an indicator of …

A

periodontal health

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15
Q

Gingival features and landmarks

A
  • attached gingiva - tightly attached to tooth and alveolar bone
  • alveolar mucosa - loosely attached to alveolar bone
  • submucosa (of alveolar mucosa)
  • free gingiva (not bound to other tissue)
  • free gingival groove
  • gingival margin
  • gingival sulcus
  • junctional epithelium
  • sulcular (crevicular) epithelium
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16
Q

What is the mucogingival junction?

A
  • boundary between alveolar mucosa (lining mucosa) - non-keratinised
  • darker colour, more translucent revealing superficial blood vessels and attached gingiva (masticatory mucosa - parakeratinised or partially orthokeratinised)
  • lighter colour shows characteristic ‘surface stipples’ in healthy gingiva
17
Q

What makes up the attached gingiva?

A
  • epithelium is thick and parakeratinised - becomes orthokeratinised
  • lamina propria - long, narrrow papillae with dense collagen fibres
  • mucoperiosteum (fibrous connection) instead of submucosa - provides stability to withstand forces of mastication
18
Q

Clinical relevance of mucoperiosteum

A
  • difficult to inject and painful for patient
  • does not require suturing (in constract to lining mucosa)
19
Q

The gingiva forms a mucoperiosteum. What does this mean?

A
  • submucosa provides mobility and acts as a ‘cushion’ e.g in lining mucosa
  • mucoperiosteum is where the lamina propria is more fibrous and directly joined with periosteum of bone e.g masticatory mucosa (middle of hard palate, gingiva)
20
Q

List groups of gingival principle fibres
Which are seen in buccal/mesial view?

A
  • transeptal - buccal
    all below mesial
  • dentogingival
  • alveogingival
  • dentoperiosteal
  • circular
21
Q

Explain transseptal gingival fibres

A
  • run interdentally from CEJ over alveolar crest to CEJ of neighbouring tooth
  • fiber system that connects all teeth to jaw
  • controls mesio-distal spacing
22
Q

Clinical relevance of transseptal fiber group

A
  • slow pace of remodelling even under mechanical stress
  • can cause post-retention relapse of orthodontically repositioned teeth
23
Q

Which is the largest and smallest group of gingival fibres?

A
  • dentogingival
  • circular
24
Q

What do dentogingival fibres do?

A
  • connect cervical cementum to lamina propria of free and attached gingiva
25
Q

What do alveogingival fibres do?

A
  • connect alveolar crest to lamina propria of free and attached gingiva
26
Q

What do dentoperiosteal fibres do?

A
  • run from cementum over outer surface of alveolar process and insert either into alveolar process or vestibular muscle/floor of mouth
27
Q

What do circular fibres do?

A
  • form band around neck of teeth and interlace with other fibres in free gingiva
  • binds free gingiva to tooth
28
Q
A
29
Q

What causes gingivitis?

A

mild inflammation

30
Q

Explain how mild inflammation causes gingivitis

A
  • dental plaque accumulation causes inflammatory response in gingival connective tissue
  • 70% of collagen fibres are destroyed within 3-4 days
31
Q

What does treatment of gingivitis aim to do?

A
  • stop spread of inflammation into periodontal tissues (PDL and bone)
32
Q

Why is there abnormal wound healing in periodontitis?

A
  • persistant inflammation causes further destruction of connective tissue by inflammatory cells
  • causes apical migration of junctional epithelium
  • formation of gingival pocket
  • advanced cases show loss of PDL and alveolar bone
33
Q

What is the mechanism of epithelial down growth?

A
  • growth until intact connective tissue is reached
  • compensation for loss of mechanical stability
34
Q

How to prevent epithelial down growth in periodontal surgery?

A
  • insertion of membrane (physical barrier)
  • formation of fibrin clot against root surface
35
Q

What is the main indicator of periodontal health?

A

depth of gingival sulcus

36
Q

What is a healthy and diseased gingival sulcus?

A
  • 0.5-2mm is healthy
  • over 3mm is diseased (a periodontal pocket)
37
Q

Is probing gingival sulcus accurate?

A
  • generally overestimates anatomic sulcus/pocket depth
  • probe usually penetrates into inflamed tissue

Craniofacial and Tooth Biology (25 decks)

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