This document provides an overview of the ultrastructure of gingival epithelium in health and disease. It defines the different parts of the gingiva and describes the microscopic features and cell types found in the oral gingival epithelium, oral sulcular epithelium, and junctional epithelium. Specifically, it discusses the keratinocytes and other cell types present, degree of keratinization, cell layers, adhesion properties, and how these epithelial areas respond in inflamed and healthy states.

1. SEMINAR ON
ULTRASTRUCTURE OF GINGIVAL EPITHELIUM
IN HEALTH AND DISEASE
BY :-
KRATI BAKLIWAL(PG 1ST YEAR)
1

2. 2
CONTENTS
• DEFINITION OF GINGIVA
• PARTS OF GINGIVA
• MICROSCOPIC FEATURES
• KERATINOCYTES
• NON KERATINOCYTES
• ORAL GINGIVAL EPITHELIUM (OGE)
• ORAL SULCULAR EPITHELIUM (OSE)
• JUNCTIONAL EPITHELIUM (JE)
• FUNCTIONS OF JE
• JE IN INFLAMED GINGIVA
• JE AROUND IMPLANTS
• EPITHELIAL REPAIR AND REGENERATION
• EXPRESSION OF KERATIN IN GINGIVA
• EXPRESSION OF CELL SURFACE ADHESION
MOLECULES IN GINGIVA
• FORMATION OF DENTAL CUTICLES
• EPITHELIAL CELL CONNECTIONS
• BIBLIOGRAPHY

3. Definition of Gingiva:
3
• The Gingiva is the part of oral mucosa
that covers the alveolar processes of the
Jaws and surrounds the neck of the teeth.
(CARRANZA)
• The Gingiva is that part of masticatory
mucosa which covers the alveolar process
and surrounds the cervical portion of the
teeth
LINDHE, KANG AND KARRING

4. PARTS OF GINGIVA
Anatomically,the gingiva is divided into three parts, it includes:
• Marginal gingiva
• Attached gingiva
• Interdental gingival.
4

5. Marginal Gingiva
The marginal , or unattached gingiva is
the terminal edge or border of the gingiva
surrounding the teeth in collar like
fashion.
5

6. - In about 50% of cases it is demarcated from the adjacent, attached
gingiva by shallow linear depression, the free gingival groove.
6

7. Usually about 1mm wide, it forms the soft
tissue wall of the gingival sulcus. It may be
separated from the tooth surface with a
periodontal probe.
•The most apical point of the
marginal gingival scallop is called
the gingival zenith
7

8. Attached Gingiva
- The attached gingiva is continuous with the
marginal gingiva.
- It is firm, resillent and tightly bounded to
the underlying periosteum of the alveolar
bone.
- The facial aspect of the attached gingiva
extend to the relatively loose and movable
alveolar mucosa, from which it is demarcated
by the mucogingival junction. 8

9. 9
Width of attached gingiva
It is generally greater in incisor region and less in
posterior segment . Least width in 1st premolar
area.
◦ Maxilla incisor region: 3.5- 4.5 mm (greatest)
•Mandible incisor region: 3.3 – 3.9 mm
◦ Maxillary premolar: 1.9 mm and
• Mandibular first premolars: 1.8 mm

10. -The width of the attached gingiva increases with age and in supraerupted teeth
-The palatal surface of the attached gingiva in the maxilla blends imperceptibly
with the equally firm and resilient palatal mucosa
10

11. Interdental Gingiva
The interdental gingiva occupies the
gingival embrasure , which is the
interproximal space beneath the area
of tooth contact.
The interdental gingiva can be
pyramidal or can have a “colˮ shaped.
11

12. • In the pyramidal the tip of one papilla
is located immediately beneath the
contact point
• the Col presents a valley like depression
that connects a facial and lingual papilla
and conforms to the shape of the
interproximal contact
12

13. 13
• The shape of the gingiva in a given interdental
space depends on the contact point between
the two adjoining teeth and the presence or
absence of some degree of recession
• -The facial and lingual surfaces are tapered
toward the interproximal contact area, whereas
the mesial and distal surfaces are slightly
concave.

14. 14
• The lateral borders and tips of the
interdental papillae are formed by the
marginal gingiva of the adjoining teeth
• The intervening portion consists of
attached gingiva
• If a diastema is present , the gingiva is
firmly bound over the interdental bone
and forms a smooth,rounded surface
without interdental papillae .

15. MICROSCOPIC FEATURES
Gingiva is composed of overlying stratified squamous epithelium and
overlying central core of connective tissue
• Epithelium : predominantly cellular
• Connective tissue: less cellular and composed primarily of collagen
fibers and ground substances
15

16. Gingival epithelium
•Consists of a continuous lining of stratified
squamous epithelium
Oral epithelium is composed of four layers –
◦ stratum basale(basal layer)
◦ stratum spinosum (prickle cell layer)
◦ stratum granulosum (granular layer)
◦ stratum corneum (cornified layer)
16

17. 17

18. •3 different areas can be defined from the morphogenic and functional point of
view
◦1 The Oral gingival epithelium(OGE)/outer epithelium
◦2 The Oral Sulcular epithelium(OSE)
◦3 The Junctional epithelium (JE)
18

19. Keratinized Epithelium:-
• In the keratinized epithelium the principal cell type is Keratinocyte which
can synthesis Keratin.
• The process of Keratinization involves a sequence of biochemical and
morphological events that occur in a cell as it migrates from the basal layer
toward the cell surface.
19

20. Keratinocytes
 Proliferation and differentiation
1. Proliferation mainly takes place by mitosis in basal layer
2. Differentiation is a process that involves keratinization
which occur through various morphologic and
biochemical events
3. These changes happen as cells migrate from basal layer.
20

21. 21
• Morphologic changes:
1. Progressive flattening of the cell with an
increasing prevalence of tonofilaments
2. Intercellular junctions coupled to the
production of keratohyaline granules
3. Disappearance of the nucleus

22. Orthokeratinized
• Superficial horny layer
• No nuclei in stratum
corneum
• Well defined stratum
granulosum
• Contains K1, K2,K10 to K12
with more intensity
22
Parakeratinized Nonkeratinized
• Retains Pyknotic nuclei
• Dispersed keratohyaline
granules
• Absence of stratum
granulosum
• Express K19 keratin
• Viable nuclei in
superficial layer
• Absence of stratum
granulosum & corneum

23. Keratinosomes
• Granules contained in the uppermost cells of spinosum layer
• They are modified lysosomes
• Also called ODLAND BODIES
• Contains acid phosphatase which is involved in destruction of organelle
membranes
23

24. Nonkeratinocytes
• Melanocytes
• Langerhans cells
• Merkel cells
24

25. Melanocytes
• Dendritic cells
• Present in Basal & spinous layers
• They synthesize Melanin in Premelanosomes or melanosomes
(melanin organelles)
• These contain tyrosinase
• Tyrosinase hydroxylates Tyrosine to dihydroxyphenylalanine
(dopa) which in turn progressively converts into Melanin.
25
TYROSINE
• IN PRESENCE OF
TYROSINASE
DOPA
MELANIN

26. 26
Langerhans cells
• Dendritic cells located among Keratinocytes
• Present in Suprabasal layer
• These are Modified monocytes belong to Mononuclear phagocyte system
(Reticuloendothelial System)
• Plays an important role in Immune reaction - antigen-presenting cells for
Lymphocytes
• g-specific granules (Birbeck’s granules)
• Found: Oral epithelium & sulcular epithelium
• Absent: Junctional epithelium

27. Merkel cells
• Located in Deeper layer of Epithelium
• Harbor nerve endings
• Connected to adjacent cells by desmosomes
• Tactile perceptors
27

28. Structural and metabolic characteristics
of Different Areas of Gingival Epithelium
28

29. Oral gingival epithelium(OGE)
•Covers the crest and outer surface of the marginal
gingiva and the surface of the attached gingiva
•On average, the oral epithelium is 0.2 to 0.3 mm in
thickness
•It is keratinized or parakeratinized or presents
various combination of these conditions
29

30. • Degree of keratinization varies with
Age & onset of menopause
• Palate > Gingiva > ventral aspect of
tongue > cheek
• has potential to loose its
keratinization when in placed in
contact with tooth
30

31. • The OGE is cornified, impermeable to water-soluble substances, and attached firmly to
a base of dense gingival connective tissue.
• Four clearly defined cell layers are present:
The basal cell layer PROLIFERATION COMPARTMENT
The spinous cell layer
The granular cell layer DIFFERENTIATION COMPARTMENT
The cornified cell layer
.
31

32. • Oral gingival epithelial cells have the lowest rate of proliferation in
comparison to JE and OSE cells.
• It has been suggested that this may be due to the physiologic restricting
effect of transforming growth factor(TGF-β) on epithelial cell
proliferation.
• The cells of the OGE have been shown to express higher levels of TGF-β
and its receptors than the cells of the OSE and JE.
32

33. • There is a high degree of interdigitation (rete peg formation) between
the OGE and the underlying connective tissue.
• Contact between the two tissues is further amplified by the presence of
numerous serrated keratinocytes and the formation of prominent cell
processes (pedicles) that protrude into the connective tissue
33

34. • Basal cells attach to the
laminadensa of the basal
lamina through the
formation of many
hemidesmosomes.
• Anchoring fibrils made of
type VII collagen bind the
lamina densa to type I and
type III collagen fibrils
34

35. • Spinous layer cells of the OGE are specialized for cell-to-cell contact via
their many desmosomes.
• These cells contain many keratin filament bundles (tonofibrils) that
associate peripherally with the attachment plaques of desmosomes
• The number of desmosomes per cell doubles from the basal to the
spinous layer
• Cell contacts of the gap junction variety are also abundant.
35

36. • Similar to the differentiation pattern found in skin , the stratum granulosum
of the OGE contains membrane- coating granules, keratohyalin granules, and
numerous tonofibrils.
• The transition to the stratum corneum is abrupt.
• The flattened cornified squamous form a relatively thick protective covering
over the connective tissue and the epithelial attachment.
36

37. 37
• In summary, the OGE:
1. Amplifies the interface between basal cells and connective tissue, to
provide a firm attachment for the epithelium.
2. Has a high level of differentiation of spinous cells to form numerous
keratin fibrils and desmosomes, serving to increase the stability of the
epithelium.
3. Develops a permeability barrier to water-soluble substances.
4. Forms a cornified protective outer layer.

38. Oral sulcular epithelium(OSE)
•Lines the gingival sulcus
•It is a thin, non-keratinized stratified
squamous epithelium without rete pegs
•It extends from the coronal limit of
the JE to the crest of gingival margin
• Lacks:
• Stratum granulosum
• Stratum corneum
• Merkels cells 38

39. • May act as Semipermeable membrane – through which injurious bacterial
products pass into tissue and GCF and tissue fluid may seep into sulcus
• Unlike the JE , the sulcular epithelium is not heavily infiltrated by PMNs
and it appears to be less permeable.
• Potential to keratinize:
• It is reflected & exposed to oral cavity
• Complete Elimination of bacterial flora of sulcus
39

40. • Regular and prolonged chemical and mechanical toothcleaning can lead to a
condition in which there is almost no sulcus.
• In the superhealthy state , achieved under experimental conditions, the JE
extends along the enamel up to the gingival margin, and the
underlying connective tissue is free of inflammatory inflltrates."
• However, most individuals who practice good oral hygiene have clinically
healthy gingiva
. 40

41. 41
• Deep interdigitations of basal cell
podocytes and connective tissue, as observed
in OGE, are not as well developed beneath the
OSE.
• Although the OSE is stratified, it does not
contain a clearly defined stratum granulosum,
nor does it normally undergo cornification.
• The differentiating compartment of OSE
contains inner and outer zones.

42. The inner zone
• It resembles a spinous layer
• But individual cells contain fewer
tonofibrils and desmosomes than
do cells in the spinous layer of the
OGE.
• Cells tend to be flattened and to lie
parallel to the epithelial surface.
The outer zone
• It contains viable cells with intact
nuclei
• It has abundant cytoplasmic
organelles
42

43. 43
• Keratin filaments are bundled into small tonofibrils that are loosely
distributed throughout the cytoplasm."
• Keratohyalin granules and membrane-coating granules are rarely
observed in cells of the OSE.
• The outermost cells contain a moderate amount of rough endoplasmic
reticulum, Golgi membranes and membrane-bound dense granules
• Although the nature of the dense granules has not been satisfactorily
established, some reports suggest that they belong to the lysosomal system,
while other reports have indicated that they might be a variant of the
membrane-coating granule.

44. OSE IN INFLAMED GINGIVA
• In inflamed gingiva, the OSE is infiltrated by numerous polymorphonuclear neutrophil
leukocytes (PMNs) and lymphocytes.
• Changes brought about by the infiltrating inflammatory cells includes:-
-a loss of desmosomes
-a widening of the intercellular spaces.
• When viewed in electron microscopes,
- The intercellular spaces of inflamed gingiva contain a fine precipitate
- Precipitate is believed to be of serum origin 44

45. • In summary, the OSE:
• 1. Does not contain keratohyalin granules.
• 2. Is normally noncornified.
• 3. Is more permeable to water-soluble substances than is the OGE.
• 4. Contains increased lysosomal activity.
45

46. Junctional epithelium(JE)
• Consists of a collarlike band of stratified squamous
nonkeratinizing epithelium
• The length of the JE ranges from 0.25 to 1.35 mm
• It is 3 to 4 layers thick in early life , but the numbers of
layers increase with age to 10- 20 layers
• JE tapers from its coronal end, which may be 10 to
29 cells wide to 1 or 2 cells wide at its apical termination
46

47. • The JE is formed by the confluence of the
oral epithelium and the reduced enamel epithelium
during tooth eruption
• The JE is attached to the tooth surface
(epithelial attachment) by means of an
internal basal lamina
• It is attached to the gingival connective
tissue by an external basal lamina
47

48. 48
• The attachment of JE to the tooth is reinforced by
the gingival fibers , which brace the marginal gingiva
against the tooth surface
• For this reason ,the JE and the gingival fibers are
considered a functional units referred to as the
dentogingival unit
• 2 strata of Junctional Epithelium:-
• Basal layer
• Suprabasal layer
• Basal cells = face gingival CT
• Suprabasal cells = extending on tooth surface
• also called as DAT cells (Directly Attached to
Tooth)

49. 49
• Junctional epithelial cells maintain
a direct attachment to the tooth
surface.
• No cuticular matrix is present
between the basal lamina and the
enamel.
• In classic histology, this first
attachment is termed the primary
epithelial attachment.
• During eruption, contact is established
between the reduced enamel
epithelium and the oral gingival
epithelium.
• Mitotic activity increases in the
reduced enamel epithelium, and
changes in cell shape and organelle
content take place as the cells merge
with the oral mucosa to form a JE.
• This process gives rise to the
secondary epithelial attachment

50. 50
• The interface between the JE and the underlying connective tissue is
relatively smooth, unlike the condition found in the OGE.
• Epithelial rete peg formation from the JE (and the OSE) is a condition
found only in highly inflamed connective tissue
.
• The number of desmosomes is significantly reduced in relation to the
number found in the OGE.
• Suprabasal cells of the JE express keratin markers typically found in basal
cells and simple epithelia.

51. 51
• At the tooth surface, the outermost epithelial cells of the JE produce an
internal basal lamina and are anchored to this basal lamina by numerous
hemidesmosornes.
• Keratin tonofilaments are not inserted into the hemidesmosomes along the
internal basal lamina.
• The internal basal lamina is approximately three times thicker than the external
basal larnina.
• The internal basal lamina contains glycoproteins, laminin, and
proteoqlycans

52. 52
• The cells in contact with the internal basal lamina contain a relatively well-
developed rough endoplasmic reticulum and numerous Golgi
components
• The external basal lamina contains collagen type IV, heparan sulfate
proteoglycan , laminin, and fibronectin.
• Anchoring fibris are less prominent in the connective tissue below the JE
than they are in the OGE.

53. • In the interdental spaces , the gingival epithelium dips apically from a
vestibular to an oral direction, forming a depression, or col , beneath the
contact point
.
• This col epithelium shares the same structural characteristics as the JE.
• The JE has a high rate of turnover.
• Daughter cells are produced along the external basal lamina .
53

54. • Cells leave the external basal lamina, migrate to the free surface of the JE
located at the base of the gingival sulcus, and are exfoliated.
• As measured in nonhuman primates , the rate of cell turnover in the JE is
approximately 5 to1O days, faster than that observed in the OSE and OGE
54

55. 55
• Mechanical separation of the JE from the tooth surface and its subsequent
replacement (as in a surgical flap procedure) leads to regeneration of the
epithelial attachment in about 7 days, accomplished by the proliferation and
migration of basal cells from the most apical part of the JE.
• Studies have shown that, following mechanical separation of the JE from
the tooth , some junctional epithelial cells remain in contact with the tooth
surface and that can proliferate to regenerate the JE attachment.

56. 56
• Another factor that may account for different proliferation rates is epidermal
growth factor (EGF).
• Cells of healthy JE contain high levels of epidermal growth factor (EGF)
and express EGF receptors.
• Under the same conditions, the OGE and the OSE are negative for EGF
and EGF receptor.
• It has been observed that EGF receptor increases in the OGE and OSE
during lnflammatlon.

57. • Tumor necrosis factor (TNF), a cytokine present in inflammatory tissue , is a
stimulator of EGF receptor expression.
• Epidermal growth factor receptor is an integral membrane protein with a
long intracellular domain that contains tyrosine kinase activity.
• Activation of the receptor by EGF leads to phosphorylation of the receptor
and other intracytoplasmic proteins, culminating in increased DNA and
protein synthesis and increased cell motility.
57

58. 58
• In healthy teeth, which have not had any prior loss of attachment, the JE
(epithelial attachment) ends at the cementoenamel junction
• Densely packed collagen bundles are anchored to the acellular extrinsic
fiber cementum just below the terminal point of the JE.
• These collagen bundles form the connective tissue attachment.
• The stability of this connective tissue attachment is a key factor in limiting
the apical migration of the JE.

59. Functions of JE
1)JE firmly attached to the tooth surface forming an epithelial barrier against
plaque bacteria
2) It allows access of gingival fluid inflammatory cells, and components of the
immunologic host defense to the gingival margin
3) JE cells exhibit rapid turnover - contributes to the host- parasite equilibrium
and rapid repair of damaged tissue.
59

60. JE IN INFLAMED GINGIVA
• In inflamed gingiva, the epithelial cells at the leading edge of a migrating
JE have no internal or external basal lamina and no hemidesmosomes.
• They resemble the epithelial cells observed at a wound edge.
• At a distance apical to the leading edge, the epithelial cells attach to
mineralized cementum by developing a basal lamina and forming numerous
hemidesmosomes.
• This attachment appears similar to that formed on enamel.
60

61. Role of JE in passive eruption:
61

62. - When the teeth reach their functional antagonists, the gingival sulcus and
junctional epithelium are still on the enamel and the clinical crown is
approximately two thirds of the anatomic crown.
- Passive eruption is divided into four stages. Although this was originally
thought to be a normal physiologic process, it is now considered a pathologic
process.
62

63. - Stage 1: The teeth reach the line of
occlusion.
- The junctional epithelium and base of the
gingival sulcus are on the enamel.
63

64. - Stage 2: The junctional epithelium proliferates so
that part is on the cementum and part is on the
enamel.
- The base of the sulcus is still on the enamel.
64

65. - Stage 3: The entire junctional
epithelium is on the cementum, and the
base of the sulcus is at the
cementoenamel junction.
- As the junctional epithelium proliferates
from the crown onto the root, it does
not remain at the cementoenamel
junction any longer than at any other
area of the tooth.
65

66. - Stage 4: The junctional epithelium has
proliferated farther on the cementum.
- The base of the sulcus is on thea cementum, a
portion of which is exposed.
- Proliferation of the junctional epithelium onto
the root is accompanied by degeneration of
gingival and periodontal ligament fibers and
their detachment from the tooth.
- The cause of this degeneration is not
understood.
- At present, it is believed to be the result of
chronic inflammation and therefore a
pathologic process.
66

67. JE AROUND IMPLANTS
• The junctional epithelium around implants always originates from epithelial
cells of the oral mucosa, as opposed to the junctional epithelium around
teeth which originates from the reduced enamel epithelium.
• Despite different origins of the 2 epithelia, a functional adaptation occurs
when oral epithelia form an epithelial attachment around implants.
67

68. • NATURAL TOOTH
-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
68

69. Epithelial repair & regeneration
• In Gingivectomy & incisional wounds:
• Undamaged epithelial cells from wound margin, migrates within hours of
injury Migrate over exposed connective tissue
• New hemidesmosomes are formed
• 1-2 days = epithelial surface is 2-3 cell thick & stratum basale forms
• By day 5 = wound is fully covered
• By day 7 = epithelium has matured & new stratum corneum formation
69

70. • In summary, the JE:
• 1. Has a high rate of proliferation.
• 2. Is noncornified and poorly stratified.
• 3. Is highly permeable.
• 4. Is the main passageway for neutrophil entry into the gingival sulcus.
70

71. Expression of Keratins in Gingiva
• Keratins (Ks) form a family of some 20 polypeptides, divided into acidic and
basic subfamilies.
• The basic to neutral keratins are numbered K1 to K8, and the smaller and
acidic keratins are numbered K9 to K19.
• Because keratin fibrillogenesis requires the assembly of pairs of acidic and
basic polypeptides, keratin molecules are usually expressed in pairs.
71

72. • K5 and K14 expressed in all stratifying epithelia
• K1,K2,K10,K11 expressed in the suprabasal cells of cornifying epithelia
• K4 and K13 expressed in the suprabasal cells of noncornifying
(and parakeratinized) stratifying epithelia.
• K6 and K16 expressed in hyperproliferative epithelia.
• K7, K8, K18, and K19 expressed by simple epithelia and are useful
markers for the localization of epithelial
neuroendocrine cells (Merkel cells).
72

73. • The availability of antibodies to specific keratins has made it possible to study
the variation in keratin expression in various oral epithelial tissues as well as in the
three separate areas of the gingival epithellurn.
• Application of immunofluorescent antikeratins to the :-
• The OGE stains for K5, K14, K1, K2, K10, K11 , K6, K8, K16, K18,
and K19 in isolated cells."
• The OSE stains for K5, K14, K4, K13, K6, K16, and K19.
• The JE expresses K5, K14, K13, and K19.
73

74. 74
• Although the JE has a high rate of turnover, there is conflicting data on
the presence of K6 and K16 in that location.
• The lack of K4 in JE marks the boundary between it and the OSE.
• The boundary between OSE and OGE is not sharply defined by keratin
types, because there is some overlap of the suprabasal cell types along the
crest of the gingiva

75. K4 K13 pair of keratins is typically expressed by
Lining mucosa associated with the
properties of flexibility and
elasticity,
K1 K10 pair expressed by
masticatory mucosa, hard palate , and skin is
associated with rigidity and toughness
75

76. Expression of Cell Surface
Adhesion Molecules in Gingiva
• Integrins are a large family of transmembrane glycoproteins, which serve to
attach cells to a large number of extracellular matrix ligands such as
fibronectin, laminin , vitronectin, tenascin , and osteopontin.
• The integrins are heterodimers formed by noncovalent association of α and β
glycoprotein subunits .
• In humans, more than 15 heterodimers are formed from at least 14 α chains
and eight β chains.
76

77. 77
• Recent studies have demonstrated that :-
• Basal cells and suprabasal cells of the JE, OSE, and OGE express the
integrins a2β1, a3β1, and a6β1.61
• The a6β1 integrin is a component of desmosomes.
• Hemidesmosomes contain the a6β4 integrin (Iaminin receptor) localized on both
the internal and external basal laminae of the JE.
• During Gingival inflammation, the expression of integrins, especially those that
function as fibronectin receptors, increases in cells of both the epithelial and
connective tissues.

78. • Calcium-binding surface adhesion molecules, the cadherins, are components of desmosomes
and adherens junctions
• Another class of cell surface adhesion molecules that is of significance to the biology of gingival
tissues is the immunoglobulin class , of which
• Intercellular adhesion molecule 1 (ICAM-1)
• Endothelial leukocyte adhesion molecule 1 (ELAM-1) Increases in gingiva during
inflammation
• Vascular cell adhesion molecule 1.
78

79. • Intercellular adhesion molecule 1 interacts with the leukocyte function-
associated antigen 1, a β2-type integrin expressed on leukocytes.
• Binding of leukocyte function antigen 1 to ICAM-1 appears necessary
for normal transmigration of neutrophils through epithelia and for the
migration of T lymphocytes into epithelial tissues.
79

80. • Intercellular adhesion molecule 1 is present on the cell membrane of JE
cells and adjacent fibroblasts and endothelial cells but absent from healthy
OSE and OGE and adjacent blood vessels
• Keratinocytes of OSE and OGE express ICAM-1 only when the adjacent
connective tissue becomes inflamed.
• Endothelial cells in the inflamed connective tissue also are
immunoreactive for ICAM-1.
80

81. • There is evidence that ICAM-1 is downregulated in epithelia of chronic
periodontal inflammatory lesions.
• However, ICAM-1 is not the only adhesion factor promoting leukocyte
adhesion to epithelial tissues, for even in the absence of positive ICAM-1
immunoreactivity there are numerous leukocytes in inflamed gingival
epithelia.
• Patients who have a genetic defect in the expression of the β2 chain of
the leukocyte function antigen 1 integrin molecule, however, suffer from
leukocyte adhesion deficiency, a condition that makes them prone to
severe infections, including prepubertal periodontitis.
81

82. • Another adhesion factor important for leukocyte transmigration in
inflammatory lesions is ELAM-1.
• Endothelial leukocyte adhesion molecule 1 has been localized on blood
vessels of gingivitis lesions
• This molecule is expressed on endothelial cells that have been activated by
cytokines such as TNF-a , IL-1, and bacterial lipopolysaccharide
82

83. Formation of Dental Cuticles
• Dental cuticles are formed by precipitation of various proteins on the tooth
surface, usually along the cervical part of the crown , between the enamel
and the junctional epithelium.
• Listgarten described and characterized two types of cuticular deposits on
the enamel surface.
83

84. • Type A cuticle
• Found on both erupted and unerupted
teeth
• Usually restricted to the cervical area
around the cementoenamel junction
• Has a granular matrix with appositional
lines and is mineralized
• Can be approximately 1 to 5 urn thick and
up to hundreds of microns in length.
• Because of its structure, location, and
ability to mineralize, it is thought to be a
form of afibrillar, acellular cementum.
• Type B cuticle
• Found only in erupted teeth
• It is located between the enamel (or a type A
cuticle) and the internal basal lamina of the
JE.
• Have no appositional lines and do not
mineralize.
• Formed by the precipitation of tissue fluid
proteins on the enamel and/or cementum
surface.
• Type B cuticles are not observed over the
enamel of unerupted teeth , suggesting that
the reduced enamel epithelium protects the
enamel surface from contact with tissue fluids
84

85. • When slices of enamel or dentin are exposed to fresh serum, a cuticle
similar to type B is deposited
• Gottlieb, a dental histopathologist of the early 20th century, described a
"primary enamel cuticle“ covering the enamel of unerupted teeth.
• He speculated that this material was the end product of ameloblastic activity.
• Listgarten was unable to confirm the presence of this structure and
concluded that it was an optical artifact produced when thick ground
sections were examined by light microscopy.
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86. Epithelial cell connections
86

87. Desmosomes
• Have typical structure consisting of two
dense attachment plaques in which
tonofilaments are inserted
• They also have an electron-dense line in
extracellular compartment
• Most common
87

88. Hemidesmosomes
• Appears as half of a
desmosome
• Has only one attachment plaque
• Involved in signaling pathways
88

89. • Gap junctions
• Allows direct chemical communication via
connexon polymers
• Tight junctions
• Less frequently observed connection
• In these the membranes of the adjoining cells
are believed to be fused
• Allow only ions and small molecules
89
Gap junctions

90. BIBLIOGRAPHY
• ORAL CELLS AND TISSUES, P.R.GRANT
• CARRANZA 12TH EDITION
• The Junctional Epithelium: from Health to Disease
(D.D. Bosshardt and N.P. Lang J Dent Res 84(1):9-20, 2005)
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