Dynamic aspect of Junctional Epithelium

© Ramaiah University of Applied Sciences
1
Faculty of Dental Sciences

2
Dr Minnu Joe Ida

3
Contents
 Permeability Of JE
 Shift Of Dentogingival Junction
 JE Adjacent To Implants
 JE In Periodontal Protection
 Role Of JE In Gingivitis
 Role Of JE In Initiation Of Pocket
 JE In NUG
 JE In TFO
 Syndromes Affecting JE
 Regeneration Of JE
 References
Introduction
Historical Aspects
 Junctional Epithelium
Definition
Functions
Development
Structure Of JE
Epithelial Attachment Apparatus
External Vs Internal Basal Lamina
Dentogingival Unit
Hemidesmosomes
Turn Over Of DAT Cells
Dynamic Aspect Of JE
JE In The Anti-microbial Defense
Expression Of Various Molecules
And Their Functions

4
Introduction
• Gingival epithelium
– Oral epithelium
– Sulcular epithelium
– Junctional epithelium

5
Junctional epithelium
• Epithelial attachment apparatus.
(Schroeder & Listgarten 1977)
• Tissue homeostasis and defense
against micro-organisms (Schroeder &
Listgarten 1997)
Bosshardt, D.D. and Lang, N.P., 2005. The junctional epithelium: from health to disease. Journal of dental research, 84(1), pp.9-20.

6
Historical aspects
1915 G V Black
Oral and odontogenic epithelium fuse into
a continuous lining as tooth erupts
1921 Gottlieb
Epithelial attachment is organically united
to the tooth surface

7
1952 Waerhaug
Based on his animal experiments, postulated that the cells of the
epithelial attachment adhere weakly to the tooth surface and it
forms the lining of the physiologic pocket
1960 Waerhaug’s concept
Epithelial cuff
1944 Orban
stated that the separation of the epithelial attachment
cells from the tooth surface involved preparatory
degenerative changes in the epithelium.

8
1966-67 Max Listgarten
Based on transmission electron microscopic studies, proved the
existence of a hemi-desmosomal basement lamina attachment between
the tooth.
1971-Schroeder and Listgarten concept
Primary epithelial attachment
secondary epithelial attachment
1981- Stern
Width of the lamina lucida 400 A

9
Terminologies
Epithelial
attachment
– Gottlieb
1921
Epithelial
cuff
-Waerhaug
1952
Attached
epithelial
cuff- Orban
1956
Attachment
epithelium-
Grant, Stern
1968
Junctional
epithelium-
Anderson
and
Stern1967

10
WHAT IS JUNCTIONAL EPITHELIUM?
• Collar like band of stratified
squamous nonkeratinizing
epithelium.
• 3 to 4 layers
• tapers from its coronal end, which
may be 10 to 29 cells wide to 1 or
2 cells at its apical termination

11
• BASAL LAYER
• SUPRABASAL LAYER
• 0.25 to 1.35mm.
• attachment mechanism of the
epithelium to the surface of
tooth
• protective function

12
DEFINITION
Junctional epithelium is the non keratinized stratified squamous epithelium
which attaches and form a collar around the cervical portion of the tooth that
follows CEJ Carranza’s clinical periodontology
A single or multiple layers of non keratinizing cells adhering to the tooth surface
at the base of the gingival crevice AAP-Periodontal literature review 1996

13
What are it’s functions?
JE is firmly attached to the tooth and thus forms an epithelial
barrier against the plaque bacteria.
It allows the access of GCF, inflammatory cells and components
of the immunological host defense to the gingival margin.
JE cells exhibit rapid turnover, which contributes to the host
parasite equilibrium and rapid repair of damaged tissue
Pöllänen, M.T., Salonen, J.I. and Uitto, V.J., 2003. Structure and function of the tooth–epithelial interface in health and disease. Periodontology
2000, 31(1), pp.12-31.
Genco RJ et al AAP 1996
1
2
3

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DEVELOPMENT OF JUNCTIONAL EPITHELIUM

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DEVELOPMENT OF JUNCTIONAL EPITHELIUM
As the tooth
erupts REE is
converted
into JE
Union of
REE and Oral
epithelium
Formation of
reduced
enamel
epithelium
Cuboidal cells derived from ameloblast begin to flatten and align parallel to
tooth surface and take appearance of JE. Since these cells which have lost
capacity to divide get exfoliated at base of sulcus and cells from stratum
intermedium which has proliferative capacity get transformed into JE

16
Tencate 1996
• Proposed that the JE which was originally derived from the
reduced enamel epithelium, may be replaced in time by a
junctional epithelium formed by basal cells originating from
the oral epithelium
Salonen et al 1989
• Stated that this holds true for the JE formed following
gingivectomy

17
Structure of junctional epithelium
• Anatomical aspects
– 0.75 to 1.35 mm
– Interproximally JE of adjacent teeth
fuse to form the lining of the col area
– Epithelial connective tissue interface
is smooth (no rete pegs)
– JE is thickest at bottom of sulcus and
tapers of in apical direction
– Coronal termination- bottom of
sulcus,gingival margin,interdental col
– Apical & lateral aspects- soft
connective tissue

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Microscopic features

19
Transmission electron microscopic features:
• Lysosomal bodies
• Poly ribosomes
• Wider intercellular
spaces
• Inflammatory cells
• Cytokeratins K5, K13,
K14, K19. Often K8, K16,
K18
• Neutrophilic
granulocytes
• Lymphocytes
macrophages
• Sensory nerve fibres

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Characteristics Outer Oral epithelium Sulcular epithelium Junctional epithelium
Origin Oral epithelium Oral epithelium Reduced enamel
epithelium
Keratinization Parakeratinized
Sometimes
orthokeratinized
Nonkeratinized Nonkeratinized
Stratification Well stratified Stratified but granulosam
and corneum are absent
Poorly stratified
Proliferation Lesser proliferation among
three
Higher than OEE but lesser
than JE
Higher proliferation
Permeability Not permeable to water
soluble substances
Moderately permeable Highly permeable
Intercellular Space
Desmosomes&
tonofilaments
Narrowest
More than SE& JE
Narrower than JE
More than JE
Widest among three
Least among three
Retepegs Present Normally absent, appears in
inflammation
Normally absent, appears
in inflammation

21
EXTERNAL Vs INTERNAL
BASAL LAMINA
features External basal lamina Internal basal lamina
Formation By basal cells with the
cross talk with
con.tissue
By DAT cells without
the influence of
fibroblast
Collagen IV Yes No
Collagen VII Yes No
Collagen VIII Not reported Yes
Perlecan Yes No
Tenascin Yes Yes(variable)
Versican Not reported Yes
Laminin 111 Yes No
Laminin 511 Yes No
Laminin 332 (Laminin
5)
Yes Yes(10 times more)

22
BASAL LAMINA
Lamina lucida
• The hemidesmosomes consist
of an attachment plaque
associated with cytokeratin
filaments and the subbasal
dense plate,which is
extracellularly located in the
lamina lucida
Lamina densa
• Directly faces the enamel,
dentin or cementum
• A dental cuticle may be
interposed between these
tooth matrices
Lamina fibroreticularis
• Forms a discontinuous layer
consisting of reticular and
anchoring fibrils and faces
the connective tissue

23
Epithelial Attachment Apparatus:
• The attachment of the JE to the tooth is
mediated through an ultramicroscopic
mechanism defined as the Epithelial
Attachment Apparatus.
• DAT (Directly Attached to the Tooth) cells
are the inner most suprabasal cells (facing the
tooth surface)
• EAA consists of hemidesmosomes at the
plasma membrane of the (DAT) cells and the
internal basal lamina on the tooth surface.

24
• The internal basal lamina proteins include
laminin and type VIII collagen
• Laminin identified as type 5 (Ln 332), is
localized mainly to the electrodense part
of the internal basal lamina and it seems
to be associated with hemidesmosomes.
• Characteristically, the internal basal lamina
lacks laminin-1 and type IV collagen which
are components of true basement
membranes

25
HEMIDESMOSOMES
• Hemidesmosomes - firm attachment
of the cells to the internal basal
lamina on the tooth surface.
• specific sites of signal transduction -
regulation of gene expression, cell
proliferation and cell differentiation

26
The hemidesmosomes at the plasma
membrane are associated with the
α6β4 integrin that communicates
with Laminin 5 located mainly in the
internal basal lamina, the
extracellular domain for BP180 is a
collagenous protein (perhaps type
VIII), that has not yet been definitely
characterized.
A schematic illustration of a DAT cell shows the structural and molecular
composition of the epithelial attachment apparatus (EAA)

27
DENTOGINGIVAL UNIT
• The attachment of JE to the
tooth is reinforced by the
gingival fibres, which brace
the marginal gingiva against
the tooth surface. Therefore,
the JE and gingival fibres are
referred to as “dentogingival
unit”
Listgarten MA 1970

28
Cuticular structures at the dento-epithelial
junction
Endogenous
• Subsurface pelllicles on enamel
• REE remnants
• Afbrillar coronal cementum
• Dental cuticle
Exogenous
• Surface pellicles

29
Turn over of the DAT cells
Morphological studies of the internal basal lamina of teeth extracted because of
advanced periodontitis have shown that remnants of the internal basal lamina can
be detected even adjacent to severely degenerated DAT cells
Mechanisms
• (1) the daughter cells produced by dividing DAT cells (Salonen et al) replace
degenerating cells on the tooth surface,
• (2) the daughter cells enter the exfoliation pathway and gradually migrate coronally
between the basal cells and the DAT cells to eventually break off into the sulcus, or
• (3) epithelial cells move/migrate in the coronal direction along the tooth surface and
are replaced by basal cells migrating round the apical termination of the junctional
epithelium
Since the surface area occupied by the basal cells is much greater than that of
the sulcus bottom,exfoliation must occur at an extremely high rate
Overman DO et al

30
Dynamic Aspect
Of JE
DAT cells migrate
toward sulcus
bottom
Intercellular spaces
of junctional
epithelium-
pathway for fluid &
transmigrating
leukocytes
Tissue fluid
transports variety of
molecules through
junctional
epithelium to
bottom of gingival
sulcus

31
Investigated renewal time in the gingival epithelium of marmosets using injections of titrated
thymidine and autoradiography
– Epithelial cells in the attached gingiva exhibited a rate of 10.4 days whereas the corresponding
rate for the epithelial cuff(concept by Waerhaug 1952) was 5.8 days
– The result suggested that the concept of a permanent epithelial attachment was unlikely, given
the rapid renewal rate of the epithelial cuff
– Used autoradiography to study the rate of migration of attachment epithelium. This study was
conducted on continuously erupting rat incisors
– They concluded that the location of the attachment is relatively stable compared to the rate of
tooth eruption, and the attachment epithelia is not proliferative tissue but epithelial cells migrate
from the down growing oral epithelium
Skougaard and Beagrie 1962
Anderson & Stern 1966

32
JE in the Anti-Microbial Defense
The first line of defense against microbial invasion into tissue.
Even though junctional epithelial cell layers provide a barrier against bacteria, many bacterial
substances, such as lipopolysaccharide, pass easily through the epithelium but have only limited
access through the external basal lamina into the connective tissue
• Rapid turnover
• The area covered by the dividing cells in the junctional epithelium is at least 50 times larger than the
area through which the epithelial cells desquamate into the gingival sulcus, there is a strong
funnelling effect that contributes to the flow of epithelial cells
• Rapid shedding and effective removal of bacteria adhering to epithelial cells
Shwartz et al 1972
Schroder et al 1967

33
EXPRESSION OF VARIOUS MOLECULES
AND THEIR FUNCTIONS
• Integrins- cell surface receptors that
mediate interactions between cells
and extracellular matrix & cell-cell
adhesion
• α6β4, α2β1,α3β1,α6β1
• Cadherins- tight contact between
cells
• E-cadherin-epithelium specific CAM-
maintain structural integrity

34

35

36

37
PERMEABILITY OF JUNCTIONAL EPITHELIUM
• Higher permeability
than the oral gingival
epithelium
• Increased
permeability is due to
– increased cell turn
over
– large intercellular
spaces
– decreased
desmosome density
*Bacterial antigens
*Lipopolysachharides
*Enzymes
*Gcf
*Antibodies
*Compliment
*Enzymes
*neutrophils

38
Shift Of Dento-Gingival Unit
Stage 1 Stage 2 Stage 3 Stage 4
Stages Of Passive Eruption by Gottlieb & Orban
The gradual gingival recession that uncovers the anatomic crown and possibly some
of the root surface is known as Passive Eruption or Exposure

39
JE adjacent to implants
Originates from epithelial cells of oral mucosa
Several marker molecules involved in defense
mechanisms are expressed in the peri-implant
epithelium
Presence of t-PA, ICAM-1 & cytokeratins profile
are documented
Functional adaptation

40
Natural teeth
• Epithelium tapers towards the
depth
• Large number of cell organelles
• Fibers are arranged perpendicular
Implant
• Epithelium is thicker
• Few organelles
• Fibers are arranged parallely
• Numerous kerato-hyalin granules

41
JE in Periodontal Protection
Extrinsic protection
Secretions of Major & minor
salivary glands
Intrinsic protection
Within & beneath the
epithelial dento gingival
junction

42
Exudation and cellular migration
GCF
• Passage of GCF (Brill & Krasse 1958)
• In a slightly inflamed gingiva, fluid may accumulate in the intercellular spaces;
such enlargements occur mainly in the coronal half of JE
Neutrophilic
granulocytes
• Migrate through JE
• 1st line of peripheral defense
• 2nd : antibody& neutrophil axis
• 3rd : monocytes& lymphocytes axis
Offenbacher 1993

43
Host defense
cells
• Mast cells, plasmablasts & langerhans cells
• Lysosomal bodies
Leukocytes
• Highest concentration- beneath the sulcus
bottom
• Decreases apically Schroeder 1970

44
ROLE OF JE IN GINGIVITIS
Stage 1
Initial lesion
Stage 2
Early lesion
Stage 3
Established lesion
Stage 4
Advanced lesion

45
ROLE OF JUNCTIONAL EPITHELIUM IN INITIATION OF POCKET FORMATION
• POCKET formation-loss of cellular continuity in the coronal most portion of the junctional epithelium
• Conversion of JE to pocket epithelium is regarded as the hallmark in the development of
periodontitis
Inflammation
Supracrestal
collagen
destruction
Lossofcontactinhibition,
OverexpressionofEGF
Apical
migration of
JE
Inflammatorycellinfiltration
Coronal
detachment
of JE
Schluger et al. 1977

46
JE in Necrotizing Ulcerative Gingivitis:
• Surface epithelium is destroyed
• And it is replaced by a meshwork of
fibrin, necrotic epithelial cells, PMNs
and neutrophils and microorganisms
• The epithelium becomes oedematous
and there is infiltration of PMNLs in the
intercellular spaces

47
JE in Trauma From Occlusion:
• JE will be intact and there will be no
degeneration of the epithelial tissues
unless there is any plaque
accumulation.
• TFO causes widening of the marginal
PDL space, a narrowing of the
interproximal alveolar bone.

48
Syndromes affecting JE:
• Kindler syndrome:
– A rare skin blistering disorder
along with early onset aggressive
periodontitis.
– Due to loss of kindlin-1 protein
which is involved in integrin
activation.
– JE fails to attach to the tooth
surface

49
Regeneration of JE
Injury
Accidental
probing, flossing or
tooth margin
preparations for
restorations.
Intentional
Periodontal surgeries
• studies on renewal of JE on tooth
and implant surface after
mechanical detachment by probing.
• Studies have been done on
mechanical trauma during flossing
and on regeneration of JE after
gingivectomy procedure which
completely removes JE.

50
Taylor& Campbell 1972
A new and complete attachment indistinguishable from that in control was
established 5 days after complete separation of the JE from the tooth
surface.
Frank et al 1972
The study demonstrated that the newly differentiated attachment apparatus
with normal hemidesmosomal attachment is possible following surgery. This
new attachment apparatus was seen on cementum as well as dentin.
Etter et al 2002
The re-establishment of the epithelial seal around implants after clinical
probing was shown to occur within about the same time period as that of the
tooth surface

51
Hemidesmosomes appeared to form prior to the basal lamina.
At 4 to 7 weeks, the basal lamina appeared complete.
Studies have also shown that the regeneration of JE after gingivectomy usually
occurs within 20 days. The formation of the new JE must occur from basal cells
of the oral epithelium .
Listgarten 1972
Waerhaug 1981
Studied the healing of the JE following the use of dental floss. Detachment of
cells persisted for 24 hrs after flossing ceased.
New attachment of JE cells started 3 days after flossing ceased. After 2 weeks ,
the cell populations on the experimental and control surfaces were
indistinguishable from each other.

52
CONCLUSION
The Junctional Epithelium is a unique tissue that fulfills challenging functions at the
border between the oral cavity and the tooth attachment apparatus. It is
structurally & functionally very well-adapted to control the constant presence of
bacteria& their products.
However its antimicrobial defense mechanisms do not preclude the development
of inflammatory lesions in the gingiva. . These defense mechanisms may be
overwhelmed by bacterial virulence factors & the gingival lesion could progress to
periodontitis.
The conversion of the JE to pocket epithelium is regarded as a hallmark in the
development of periodontitis.

53
REFERENCES
 Bartold, Biology Of Periodontal Tissues
 Bosshardt, D.D. and Lang, N.P., 2005. The junctional epithelium: from health to
disease. Journal of dental research, 84(1), pp.9-20.
 Carranza, Clinical Periodontology 12th Ed
 Garant P R Oral Cells And Tissues
 Grant Stern & Listgarten Periodontics 6th Ed
 Lindhe Clinical Periodontology & Implant Dentistry- 5th Ed
 Orban’s Oral Histology And Embryology 12th Ed
 Pöllänen, M.T., Salonen, J.I. and Uitto, V.J., 2003. Structure and function of the
tooth–epithelial interface in health and disease. Periodontology 2000, 31(1), pp.12-
31.
 Tencate A R Oral Histology 6th Ed

54

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