This document discusses the junctional epithelium, which is the stratified non-keratinizing epithelium that surrounds the tooth like a collar. It forms the floor of the gingival sulcus and attaches the gingiva to the tooth surface. The junctional epithelium has two basal lamina layers and is unique in that it attaches to the tooth through hemidesmosomes. It develops from the reduced enamel epithelium during tooth eruption. The junctional epithelium provides both an attachment role and a protective role through its permeability. The position of the dentogingival junction can shift through passive eruption as the gingiva recedes over time.

1. JUNCTIONAL EPITHELIUM
Nabin chaudhary
BDS 2011

2. Junctions in oral mucosa
• Junctions in the oral mucosa are
lines or surfaces, where two
different types of mucosa meet
each other.
• Within the oral mucosa there are
three junctions:
• Mucocutaneous junction – the
site of transition between skin
and mucous membrane.
• Mucogingival junction – between
gingiva and alveolar mucosa
• Dentogingival junction –
between tooth and free gingiva

3. Gingiva
• Gingiva is that portion of the
oral mucosa that covers the
tooth-bearing part of the
alveolar bone and the cervical
neck of the tooth
• Masticatory mucosa
• Morphologically gingiva is
divided into:
1. Attached gingiva
2. Free gingiva
3. The interdental papilla.

4. Dentogingival junction
• Defined as the oral epithelium that
extends from the mucogingival
junction to the gingival margin where
crevicular/sulcular epithelium lines
the sulcus
• Sulcular epithelium+junctional
epithelium=dentogingival junction
• Gingival sulcus has a depth of 0.5-
3mm(avg.1.8mm)
• Any depth greater than
3mm,considered pathologic,a sulcus
this depth is known as a periodontal
pocket

5. Epithelial components of gingiva
• The gingival epithelium is
subdivided into 3 sections:
• the oral epithelium (OE),
• the sulcular epithelium (SE),
and
• the junctional epithelium
(JE).

6. Junctional epithelium
• Junctional epithelium is the
stratified non-keratinizing
epithelium, that surrounds the
tooth like a collar with a cross-
section resembling a thin
wedge.
• The epithelium of the gingiva
which gets attached to the
tooth is called junctional or
attatchment epithelium.

7. • Forms the floor of sulcus
and attaches gingiva to
tooth surface
• The union between this
epithelium and tooth is
referred to as epithelial
attachment. It is bounded
CORONALLY by the free
gingival groove and
APICALLY by the
mucogingival junction
• Resembles REE in its
structure in that they have a
basal layer and few layers of
flattened cells

8. Arrangement of cells in attachment
epithelium

9. Junctional epithelium is unique as it possess 2
basement membranes – the internal and
external basal lamina
Enamel
Lamina
propria
Internal Basal Lamina External Basal Lamina
Hemidesmosomes

10. • The junctional epithelium has
2 basal laminas, one that faces
the tooth (internal basal
lamina) and one that faces the
connective tissue (external
basal lamina).
• The proliferative cell layer
responsible for most cell
divisions is located in contact
with the connective tissue, i.e.
next to the external basal
lamina.

11. • Cells of JE immediately adjacent to tooth attach to tooth by
hemidesmosomes & basal lamina i.e. Internal Basal lamina
• Combination is known as the epithelial attachment,adhesive forces betn
this zone are molecular in nature and act across a distance smaller than
4onm(400Ang)
• On opposite surface – JE in contact with lamina propria of gingiva &
attached by hemidesmosomes and basal lamina i.e. External Basal
Lamina
• IBL differs from EBL in that they lack laminin,anchoring fibrils and type IV
collagen
• Cells of JE are attached to eachother primarily by desmosomes,and also
by tight and gap junctions

12. Cont…
• Coronally: 15-30 layers thick. Apically: narrows to 3-4 layers
thick
• Extends upto 2mm on the surface of the tooth
• Contains fewer tonofilaments and desmosomal junctions
• Cytokeratins present are CK5,CK14,CK19(simple epithelia has
CK8,CK18)

13. • Shows no sign of differentiation to form a keratinized surface
epithelium
• highest turnover rate of 5-6 days
• Highly permeable and it has large intercellular spaces,so that
neutrophils have an easy passage in and out of the epithelium
• Also permits the easy flow of crevicular(gingival) fluid
• The junctional epithelium is more permeable than the oral or
sulcular epithelium.

14. Significance of JE
• Has attachment role and protective role
• Helps maintain integrity of tooth / periodontium structure.
• Permeability allows GCF and defence cells to pass across to
protect underlying tissues from disease processes (periodonal
disease)
• GCF contains g globulins and polymorphonucleocytes (PNMs)
giving it immunological / phagocytic properties to combat
disease processes

15. • The lysosomes of the junctional epithelium may have a
phagocytic function
• Langerhans cells migrate to sulcular and oral epithelium
when infection or inflammation is present
• These defence rxns to the bacteria in the gingival sulcus
constitute barriers against the invasion of bacteria and
the penetration of toxins

16. • A diagnosis of gingivitis implies that the actual level of the
junctional epithelial attachment has not migrated apically, but is still
on the enamel or on the cementoenamel junction
• A diagnosis of periodontitis implies that the junctional epithelium
has migrated apically two, three, or more millimeters from its
original level at the cementoenamel junction

17. Development of junctional junnction
• Junctional epithelium is derived from Reduced Enamel
Epithelium(REE)
• Ameloblast after formation of enamel matrix they leave a thin
membrane on the surface of enamel PRIMARY ENAMEL
CUTICLE.
• Ameloblasts cells becomes flat cuboid cells – REE
• As tooth erupts and crown penetrates overlying oral
epithelium a fusion occurs between REE and oral epithelium
so that epithelium continuity is never lost

18. • Remnants of PEC after eruption– NASMYTH’S MEMBRANE.
• Tip of crown emerged, the REE termed as PRIMARY ATTCHEMENT
EPITHELIUM
• As Tooth erupts,REE grows shorter and forms gingival sulcus.
• The replacement of primary attachment epithelium by cells derived
from gingival epithelium is called secondary attachment epithelium

23. Shift of dentogingival junction
• Position of gingiva on the surface of the tooth changes with
time
• active eruption refers to the bodily movement of the
developing tooth through the overlying jawbone and oral
mucosa into the oral cavity.
• Active eruption normally stops when the erupting tooth
comes in contact with its antagonist in the opposite jaw.
• Passive eruption refers to the uncovering of the anatomic
crown because of apical recession of the surrounding tissues,
rather than bodily movement.

24. • Passive eruption has been
classified into 4 stages
• stage 1: bottom of the
gingival sulcus remains on
enamel & apical end of
attachment epithelium at CEJ
• The junctional epithelium is
located entirely over the
enamel.
• Persists in primary teeth for 1
yr of age before shedding and
in permanent teeth upto 20-
30 yrs

25. • stage 2: bottom of GS on the
enamel & apical end of
attachment epithelum is shifted
to the surface of cementum
• The junctional epithelium is
located in part over the enamel
and in part over the cementum
• Apical migration of sulcus is the
result of detachment of basal
cells and reestablishmrent of
their epithelial attachment at a
more apical level
• Dissolution of fibre bundles that
were anchored in cervical parts of
cementum,caused by enzymes
formed by epithelial cells,by
plaque metabolites or
immunologic rxns
• Persists upto 40 yrs or later

26. • Stage 3: Bottom of the GS at
CEJ & epithelial attachment
entirely on the cementum
• The entire junctional
epithelium is located over
cementum, with its coronal
end at the cemento-enamel
junction

27. • Stage 4: Recession of
gingiva(The entire
junctional epithelium is
located apical to the
cemento-enamel
junction)

28. • 1st and 2nd stages (passive
eruption),anatomic crown
is larger than clinical
crown
• 3rd and 4th represent
recession
• In 3rd stage,anatomic and
clinical crowns are equal
• In 4th stage, clinical crown
is larger than anatomic
crown

30. Dynamics of migration of tissues of dentoepithelial
junction

31. Enamel Cuticle
• When the ameloblasts are replaced by oral epithelium a secondary
cuticle is formed
• Amorphous material between JE and underlying hard tissue
• Not visible in demineralised sections
• Cuticle also seen between JE and underlying cementum
• Secondary Enamel cuticle and cemental cuticle=dental cuticle

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