Junctional Epithelium / Epithelial Attachment

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Junctional Epithelium / Epithelial Attachment

• What and where it is
• Where it comes from
• What it does
• Why it does it

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What and Where is the Junctional Epithelium

• Epithelial attachment and clinical attachment
  level
• Collar-like band of nonkeratinised stratified
  squamous epithelium
• Extends from cementoenamel junction - bottom of
  gingival sulcus
• Coronally 15-30 cells thick. Apically narrows
  to 1-3 cells
• Length 0.25 1.35mm has rate of turnover

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A- gingiva B- sulcular epithelium C- junctional
epithelium D- lamina propria (connective
tissue) E- alveolar process F- PDL
ES- enamel space JE junctional epithelium CT-
connective tissue
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Where does it come from ?

• Initially derived from Reduced Enamel Epithelium
• REE replaced once tooth erupts REE covering
  crown lost rapidly replaced by squamous
  epithelial cells
• Transformed REE oral epithelium form
  dentogingival junction and junctional epithelium
• Final conversion of REE to JE may not occur until
  3-4 years post eruption

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Important Features

• Cells of JE immediately adjacent to tooth attach
  to tooth by hemidesmosomes basal lamina
• Combination is known as the epithelial attachment
• Basal lamina in contact with tooth Internal
  Basal lamina
• On opposite surface JE in contact with lamina
  propria of gingiva attached by hemidesmosomes
  and basal lamina
• Basal lamina in contact with lamina propria
  External Basal Lamina

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Junctional epithelium is unique as it possess 2
basement membranes the internal and external
basal lamina
Enamel
Lamina propria
Hemidesmosomes
Internal Basal Lamina
External Basal Lamina
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JE
CT
External basal lamina
Enamel space
Internal basal lamina
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Enamel Cuticle

• Not visible in demineralised sections
• Non-mineralised structure between JE and
  underlying hard tissue
• Cuticle also seen between JE and underlying
  cementum

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Length of Junctional Epithelium

• Length varies according to stage of eruption
• Tooth first erupts most of enamel covered by JE
• Tooth reaches occlusal plane ¼ enamel surface
  covered
• Eventually JE lies close to CE junction
• Older patients with root exposure (passive
  eruption or disease) JE proliferates apically -
  firm attachment with cementum

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Other Fantastic Facts You Really Wanted to Know
About the Junctional Epithelium!!!!

• Lamina propria of gingiva good vaculature and
  source of nutrient to JE and source of GCF
• JE is permeable tissue fluid and cells pass
  into GCF
• Turnover of JE is rapid. Epithelial cells migrate
  coronally shed into oral cavity via gingival
  crevice
• Rate of turnover dependent on demands placed on
  tissue. Directly related to degree of inflammation

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What it does and why it does it

• Has attachment role and protective role
• Permeability allows GCF and defence cells to
  pass across to protect underlying tissues from
  disease processes (periodonal disease)
• Helps maintain integrity of tooth / periodontium
  structure.

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Role of JE Clincial significance

• GCF contains g globulins and ploymorphonucleocytes
  (PNMs) giving it immunological / phagocytic
  properties to combat disease processes
• Such molecules pass readily across JE to
  underlying tissues
• JE ( GCF) good indicator for severity of
  periodontal disease may contain neutrophils
  other inflammatory cells indicating disease
  state of health of periodontium
• Research into this ongoing in Bham
  understanding progression of disease
  development of diagnostic marker of severity of
  disease

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Reason why I have not been around for the past 2
weeks!!