Junctional Epithelium / Epithelial Attachment What and where it is

Junctional 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 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 ?

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 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
possess 2 basement membranes – the
internal and external basal lamina
Enamel
Lamina
propria
Hemidesmosomes
Internal Basal Lamina
External Basal Lamina
JE
Enamel space
Internal basal lamina
CT
External basal lamina
Enamel 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 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
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 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 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!!