Junctional Epithelium / Epithelial AttachmentJunctional Epithelium / Epithelial Attachment

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

What and Where is the Junctional EpitheliumWhat 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

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

Where does it come from ?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

Important FeaturesImportant 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

Junctional epithelium is unique as it Junctional epithelium is unique as it possess 2 basement membranes – the possess 2 basement membranes – the

internal and external basal laminainternal and external basal lamina

Enamel

Lamina propria

Internal Basal Lamina External Basal LaminaHemidesmosomes

CTJE

Enamel space Internal basal laminaExternal basal lamina

Enamel CuticleEnamel Cuticle

Not visible in demineralised sections

Non-mineralised structure between JE and underlying hard tissue

Cuticle also seen between JE and underlying cementum

Length of Junctional EpitheliumLength 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

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

What it does and why it does itWhat 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.

Role of JE – Clincial significanceRole 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

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