Ultrastructure of gingiva

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Ultrastructure of gingiva including
histochemistry and microcirculation
Presented by:
Dr. Md. Naseem Ashraf
2nd Year Post Graduate

CONTENTS:
INTRODUCTION
DEFINITION
MACROSCOPIC FEATURES
– Marginal gingiva
– Gingival sulcus
– Attached gingiva
– Interdental gingiva
MICROSCOPIC FEATURES
– Gingival epithelium
– Gingival Connective tissue
HISTOCHEMISTRY & MICROCIRCULATION
CORRELATION OF CLINICAL AND MICROSCOPIC FEATURES
– Color
– Size
– Contour
– Shape
– Consistency
– Surface texture
CONCLUSION
 REFERENCES

Tissue that support and invest the teeth are collectively referred to as the
periodontium.
Periodontium includes :
Two soft connective tissues
i. Gingiva
ii. Periodontal ligament
Two hard connective tissues
i. Alveolar bone
ii. Cementum
Introduction:

Definition:
Mucosa: A mucous membrane.
Masticatory Mucosa: The gingiva and the mucosal covering of the hard
palate.
Oral Mucosa: The tissue lining the oral cavity.
Alveolar Mucosa: Mucosa covering the basal part of the alveolar process
& continuing without demarcation into the vestibular fornix & the floor of
the mouth. It is loosely attached to the periosteum and is movable.

Gingiva:
 The fibrous investing tissue, covered by keratinized epithelium, which
immediately surrounds a tooth and is contiguous with its periodontal ligament
and with the mucosal tissues of the mouth.
- AAP 1992
 The gingiva is the part of masticatory mucosa which covers the alveolar process
and surrounds the cervical portion of the teeth.it consists of an epithelial layer
and an underlying connective tissue layer called the lamina propria.
- JAN LINDHE,5TH EDITION

 The gingiva is the part of the oral mucosa that covers the alveolar
processes of the jaws and surrounds the necks of the teeth.
- CARRANZA’ 10TH EDITION
 The gingiva is the oral mucosa encircling the necks of the teeth and,
it fully covers the root surface and supporting alveolar bone.
- P.MARK BARTOLD

Macroscopic Features
Gingiva is divided anatomically into marginal, attached,
and interdental areas. (Schluger et al 1990)

Marginal Gingiva
 Marginal or unattached gingiva is the terminal edge or border of the
gingiva surrounding the teeth in collarlike fashion.
 In about 50% of cases, it is demarcated from the adjacent, attached
gingiva by a shallow linear depression, the free gingival groove.
 Usually about 1 mm wide, it forms the soft tissue wall of the gingival
sulcus.
 It may be separated from the tooth surface with a periodontal probe.

Gingival sulcus
 Shallow crevice or space around the tooth bounded by the surface
of the tooth on one side and the epithelium lining the free margin
of the gingiva on the other.
 V shaped ; barely permits the entrance of a periodontal probe.
 In normal or clinically healthy gingiva there is no "gingival
pocket" or "gingival crevice’’ present.
 Clinical determination of the depth of the gingival sulcus is an
important diagnostic parameter.

Depth of Gingival Sulcus :
Ideal conditions - zero. {Pristine Gingiva. (Gottlieb, Orban 1933)}
Clinically - 2 – 3 mm.
Histologic -1.8 mm with variations from 0 to 6 mm

Attached gingiva
 Continuous with marginal gingiva & is firm, resilient & tightly
bound to the underlying periosteum of the alveolar bone.
 Facial aspect of the attached gingiva extends to the relatively
loose & movable alveolar mucosa from which it is demarcated by
the mucogingival junction.

Mucogingival junction (MGJ), can be localized
Functionally by :
 Passive movement of the lips and cheeks
Anatomically by :
Differences of color & surface characteristics such as stippling
Histochemically by:
Application of Schiller’s iodine solution to reveal the glycogen
stored in the epithelium of the lining mucosa
Normally, this junction resides about 3-5mm apical to the level of
the alveolar crest.

Width of the attached gingiva
 Distance between the mucogingival junction and the projection
on the external surface of the bottom of the gingival sulcus or the
periodontal pocket.
 Width of the attached gingiva on the facial aspect differs in
different areas of the mouth (Bower G, 1963) ."
Greatest in incisor region : (Ainamo and Loe 1966)
3.5 to 4.5 mm in maxilla
3.3 to 3.9 mm in mandible
Least width in the first premolar area :
1.9 mm in maxilla
1.8mm in mandible

 MGJ remains stationary throughout adult life. (Ainamo A,1978)
 Width of attached gingival increases with age(Ainamo J,1976)
 On lingual aspect, AG terminates at the junction with the lingual alveolar
mucosa, which is continuous with the mucous membrane lining the floor
of mouth.
 On palatal surface, it blends imperceptibly with the equally firm, resilient
palatal mucosa.

Functions and clinical importance
 Dissipates functional and masticatory stresses
 Provides a resistant barrier to plaque induced inflammation
 Prevents Recession
 Deepens vestibule to provide better access for tooth brushing
 The width is determined by subtracting the sulcus or pocket
depth from total width of gingiva.
Methods of measuring the width of Attached Gingiva

"Inadequate" zone of gingiva
 Facilitate subgingival plaque formation because of improper pocket
closure resulting from the movability of the marginal tissue (Friedman
1962)
 Favor attachment loss and soft tissue recession because of less tissue.
 Accumulation of food particles during mastication
 Impede proper oral hygiene measures (Gottsegen 1954, Rosenberg
1960, Corn 1962, Carranza & Carraro 1970)

How much zone of keratinized gingiva is necessary to
maintain the health of Periodontium?
 Landmark Study : Lang & Loe
 First controlled Clinical Trial When the tooth surfaces kept free of
clinically detectable plaque.
 Surfaces >2mm of keratinized gingiva= Healthy
 Surfaces < 2mm of keratinized gingiva=Inflammed
 Which means 1mm or less than 1mm of attached gingiva remain
inflamed
 Lang & Loe strongly suggested that 2mm width of keratinized
gingiva is important for maintaining the health.

Bower said that less than 1mm of attached gingiva may be sufficient.
 According to Wennstorm,
The lack of minimum amount of attached Gingiva does not necessary
result in a soft tissue recession.
The narrow attached gingiva apical to localized recession is a result of
recession rather than cause.
Proper plaque control prevents soft tissue recession, even when it is out
of adequate width.

Interdental Gingiva
• Occupies the gingival embrasure, which is the
interproximal space beneath the area of tooth contact
• can be pyramidal or have a "col" shape
PYRAMIDAL SHAPE-
In this the papilla is located immediately beneath the
contact point.

COL SHAPE
• It is valley like depression that
connects the facial and lingual
papilla and conforms to the shape
of interproximal contact .
• Its epithelium is non keratinised
and same as junctional epithelium

MICROSCOPIC ANATOMY
• Gingival tissues ; composed of a superficial epithelium of ectodermal
origin and an underlying c/t of mesodermal origin. (Listgarten 1972;Mackenzie
1988)
• Gingiva consists of a central core of c/t covered by stratified squamous
epithelium.
Epithelium: Predominantly cellular in nature, Connective tissue is less cellular
and composed primarily of collagen fibres and ground substance.

Gingival epithelium
 Oral/outer epithelium
 Sulcular epithelium
 Junctional epithelium
Gingival epithelium is functionally and
morphologically classified into three parts:

• Physical barrier to infection and the underlying gingival attachment.
• Play an active role in innate defense by responding to bacteria in an
interactive manner.(Dale BA, Periodontol 2000 30:70, 2002 )
Principal cell type - keratinocyte.
 Clear cells or non keratinocytes which include the Langerhans cells,
Merkel cells, and Melanocytes

• Main function is to protect the deep structures, while allowing a
selective interchange with the oral environment.
• Achieved by proliferation and differentiation of the keratinocyte
Proliferation of the keratinocyte occurs by mitosis in basal layer.
Differentiation involves a series of biochemical and morphological
events that occur in the cell as it migrates from the basal to the
superficial layers.

The main morphological change is a:
Progressive flattening of the cells with an increasing prevalence
of tonofilaments.
 Intercellular junctions coupled to the production of
keratohyaline granules.
 Disappearance of nucleus.

• Complete keratinization process leads to the production of an
Orthokeratinized.
• Some areas are orthokeratinized; the other gingival areas are covered
by parakeratinized or nonkeratinized epithelium(Cabrini RL,Carranza
FA Jr,1951)
• Parakeratinized epithelia the stratum corneum retains pyknotic
nuclei, & keratohyalin granules are dispersed, not giving rise to
stratum granulosum.
• Non keratinized epithelium has neither granulosum nor corneum
strata ,where as superficial cells have viable nuclei.

During the maturation process cytokeratins are
 Synthesized, other proteins unrelated to keratins are synthesized
such as keratolinin , involucrin which are precursors of chemical
resistant structure (envelope) located below the cell membrane.
There are no fibrous protein components of the epithelial
extracellular matrix. Non fibrous epithelial components include
water and a variety of glycoproteins, lipids and proteoglycans, and
extensions of intercalated cell surface molecules (Bartold,1987)

Gingival epithelium can synthesize extracellular products such as
proteoglycan and other glycoproteins (Braun-Faulco 1959)
Proteoglycans identified in human gingival epithelial intercellular
spaces are hyaluronan, decorin, syndecan and CD44(Hakkinen et al
1993;Tammi et al 1990

Various layers of Stratified Squamous Epithelium

Stratum basale
• Cells in the basal layer are either cylindric or cuboid, and are in
contact with the basement membrane that separates the
epithelium and the connective tissue.
• The basal cells possess the ability to divide, i.e. undergo mitotic
cell division.

• It is in the basal layer that the epithelium is renewed.
• Also termed stratum germinativum, considered progenitor cell
compartment of the epithelium.
• Under the light microscope this membrane appears as a structure less zone
which reacts positively to a PAS stain (periodic acid-Schiff stain).
• Demonstrates that the basement membrane contains carbohydrate
(glycoproteins).

Stratum Spinosum:
• Consists of 10-20 layers of relatively large, polyhedral cells,
equipped with short cytoplasmic processes resembling spines.
• Cytoplasmic processes occur at regular intervals and give the
cells a prickly appearance.

• Uppermost cells of the stratum spinosum contain numerous dense
granules, keratinosomes or Odland bodies, which are modified
lysosomes.
• Contain large amount of acid phosphatase, an enzyme involved in the
destruction of organelle membranes, which occurs suddenly between the
granulosum and corneum strata and during the intercellular cementation
of cornified cells.
• Thus acid phosphatase is another enzyme closely related to the degree of
keratinization.

Stratum Granulosum And Stratum Corneum
• Keratohyalin granules are seen in the stratum granulosum.
• There is an abrupt transition of the cells from the stratum
granulosum to the stratum corneum.
• This is indicative of a very sudden keratinization of the cytoplasm
of the keratinocyte and its conversion into a horny squame

• Cytoplasm of the cells in the stratum corneum is filled with keratin
& entire apparatus for protein synthesis and energy production, i.e.
the nucleus, the mitochondria, the endoplasmic reticulum and the
Golgi complex, is lost.
• A complete keratinization process leads to the production of an
orthokeratinized superficial horny layer with no nuclei in the
stratum corneum and a well-defined stratum granulosum.

• Other gingival areas are covered by parakeratinized or nonkeratinized
epithelium, considered to be at intermediate stages of keratinization.
• These areas can progress to maturity or differentiate under different
physiologic or pathologic conditions.
• In parakeratinized epithelia, the stratum corneum retains pyknotic nuclei
and the keratohyalin granules are dispersed, not giving rise to a stratum
granulosum.

• Nonkeratinized epithelium (although cytokeratins are the major
component, as in all epithelia) has neither granulosum nor corneum
strata, nor superficial cells have viable nuclei..
Differentiation involves the process of keratinization, which consists
of a sequence of biochemical and morphologic events that occur in the
cell as it migrates from the basal layer

Cells lose the ability to multiply by mitotic
division
Cells produce amounts of protein, & accumulate
keratohyalin granules, keratin filaments &
macromolecular matrix in their cytoplasm
Cells lose cytoplasmic organelles responsible for
protein synthesis & energy production
Cells eventually degenerate into cornified layer
due to the process of intracellular keratinization,
but without loss of cell-cell attachment
Cells finally sloughed away from epithelia surface
& into the oral cavity as the cell-cell attachment
mechanisms ; ultimately disintegrate.

Nonkeratinocyte cells
Lack desmosomal attachment to adjacent cells.
Melanocytes which originate from neural crest cells are dendritic
cells synthesizes melanin in organelles called premelanosomes or
melanosomes .
These contain tyrosinase, which hydroxylates tyrosine to
dihydroxyphenylalanine (dopa), which in turn is progressively
converted to melanin.
Melanin granules are phagocytosed and contained within other cells
of the epithelium and connective tissue, called melanophages or
melanophores.

Langerhans cells
Dendritic cells located among keratinocytes at all suprabasal levels.
Belong to the mononuclear phagocyte system (reticuloendothelial
system) as modified monocytes derived from the bone marrow.
Contain elongated granules and are considered macrophages with
possible antigenic properties.
Important role in the immune reaction as antigen-presenting cells for
lymphocytes.
Found in : oral epithelium of normal gingiva & in smaller amounts in
sulcular epithelium; absent from junctional epithelium

Merkel cells
Located in the deeper layers of the epithelium, harbor nerve
endings, it is not dendritic, it does possess keratin tonofilaments and
occasional desmosomes linking it to adjacent cells . They have been
identified as tactile perceptors.

Inflammatory cells
Cells are transient and do not reproduce themselves in the epithelium.
Cell most frequently seen is the lymphocyte, presence of
polymorphonuclear leukocytes & mast cells is not uncommon.
Lymphocytes often associated with langerhans cells, which are able to
activate T lymphocytes.
Few inflammatory cells are in the oral epithelium ; can be regarded as a
normal component of the non-keratinocyte population.

Structural and Metabolic Characteristics of the Different Areas of
Gingival Epithelium
Oral Epithelium:
The oral or outer epithelium covers the crest and outer surface of the
marginal gingiva and the surface of the attached gingiva.
It is keratinized or parakeratinized or presents various combinations of
these conditions.
 The prevalent surface, however, is parakeratinized.
Degree of gingival keratinization diminishes with age. Keratinization of
the oral mucosa varies in different areas in the following order: palate (most
keratinized), gingiva, ventral aspect of the tongue, and cheek (least
keratinized)

Keratins K1, K2, and K10 to K12, which are specific of epidermal-
type differentiation, are immunohistochemically expressed with high
intensity in orthokeratinized areas and less intensity in parakeratinized
areas.
K6 and K16, characteristic of highly proliferative epithelia, and K5
and K14, stratification-specific cytokeratins, also are present.
Parakeratinized areas express K19, which is usually absent from
orthokeratinized normal epithelia.

Sulcular Epithelium.
Lines the gingival sulcus.
It is a thin, nonkeratinized stratified squamous
epithelium without rete pegs and extends from the
coronal limit of the junctional epithelium to the crest
of the gingival margin.
lacks granulosum and corneum strata and K1, K2,
and K10-K12 cytokeratins, but it contains K4 and
K13, the so-called esophageal type cytokeratins.
It also expresses K19 and normally does not contain
Merkel cells.

It has the potential to keratinize if :
(1) it is reflected and exposed to the oral cavity
(2) the bacterial flora of the sulcus is totally eliminated .
 The outer epithelium loses its keratinization when it placed in
contact with the tooth.
 These findings suggest that the local irritation of the sulcus
prevents sulcular keratinization.
 Act as a semipermeable membrane through which injurious
bacterial products pass into gingiva and tissue fluid from the
gingiva seeps into the sulcus.

Junctional epithelium
 The term JUNCTIONAL EPITHELIUM was given by Anderson
and Stern (1966).
The junctional epithelium consists of a collar like band of stratified
squamous nonkeratinizing epithelium. It is three to four layers thick in
early life, but the number of layers increases with age to 10 or even
20 layers. (Carranza 11th edition)
The epithelium of the gingiva which gets attached to the tooth is
called junctional epithelium or attachment epithelium.
(Orbans)

HISTORICAL BACKGROUND
 Less than a century ago it was believed that the fibres of the
ligament lay parallel to the tooth surface and the gingiva
contracted the tooth at CEJ

G.V. BLACK’S CONCEPT :
In young individuals a capillary space (gingival sulcus) extended from
the gingival margin to the cemento-enamel junction.
He observed a zone of perfect, unstained enamel, free of caries
Therefore, the gingival margin of a proximal restoration should be
placed into this zone which was believed to be part of the sulcus and
immune to dental caries.
Towards the end of 19th century and the beginning 20th century it was
believed that a subgingival space extended to the CEJ under a loose fitting
gingiva. (G.V Black,1915)

ORBAN in the time period of 1921 to 1953
The reduced enamel epithelium as containing shortened ameloblasts, and as
the epithelium which, after fusion with the oral epithelium, becomes the
'epithelial attachment'.
According to GOTTLEIB, 1921, gingiva forms an organic union with the
enamel and is firmly bound to it and he named it as “Der Epithelansatz am
Zahne" (The epithelial attachment to the tooth)
He said union between ameloblasts and the forming and maturing enamel
rods occurs after the final calcification of the enamel matrix.

He stated that the bottom of the gingival sulcus was located where
the cuticle began floating freely in his specimen and passive exposure
of tooth is due to “peeling back “of epithelial attachment.
WAERHAUG CONCEPT, 1952
He described the gingiva as being separated from the tooth by a
capillary space, forming an epithelial cuff weakly adherent to the
tooth, and could be displaced from the tooth surface and then
replaced against it without diminishing the strength of the adhesion.

First demonstrated that the ultra structure of the epithelium of the
ameloblast-enamel junction (the dentogingival junction ) of rat incisor
consists of a basal lamina and hemidesmosomes, and that the basal
lamina has components namely Lamina lucida and a Lamina densa.

In 1962, STERN
First demonstrated that the ultrastructure of the epithelium of the
ameloblast-enamel junction (the DGJ) of rat incisor consists of a basal
lamina and hemidesmosomes and that the basal lamina has as components
a lamina lucida and a lamina densa.
This observation of a basal lamina and hemidesmosomes, plus those of
other workers has led to a resolution of the controversy.
Neither concept, Waerhaug’s epithelial adherent cuff nor Gottlieb’s firm
organic union of the last formed product of the reduced enamel organ
bonding to the gingiva of the tooth, is correct.

HUBERT SCHROEDER,1968
Indicated that the junctional epithelium is a non-keratinizing, non-
differentiating, fast-renewing epithelium with distensible intercellular
spaces that serve as a pathway for an inflammatory exudates and
neutrophilic granulocytes, as a residence for lymphocytes and
monocytes, as well as for the inward diffusion of foreign molecules.
These concepts have been replaced by the concept of t
he JE, a tissue capable of forming and renewing itself
continuously throughout life. Thus, the
former relatively
static concepts have been replaced by a dynamic
concept

THE DEVELOPMENT OF THE JUNCTIONAL EPITHELIUM
The junctional epithelium forms as the tooth crown erupts into the
oral cavity.
Prior to the emergence of the tooth into the oral cavity, the enamel
surface is covered by the reduced enamel epithelium that consists of
reduced ameloblasts and the remaining cells of all other layers of the
enamel organ.

The stratum intermedium cells of the reduced enamel epithelium and the oral
epithelial cells proliferate following breakdown of the interposed connective
tissue (Ten Cates, 1998).
The 2 epithelia eventually fuse to form an epithelial cell mass.
When the tips of the cusps or the incisal edge of the crown breaches the oral
mucosa (Ten Cates, 1998), or shortly before the establishment of the first contact
between the reduced enamel epithelium and the oral gingival epithelium
(Schroeder, 1996), a slow cell transformation process develops.

Beginning orally and ending at the cemento-enamel junction 1
to 2 (Schroeder and Listgarten, 1977) or 3 to 4 (Ten Cates, 1998) yrs later, the
reduced enamel epithelium gradually converts into junctional epithelium, a
multilayer non-keratinizing squamous epithelium (Glavind and Zander, 1970;
Listgarten, 1972; Schroeder and Listgarten, 1977; Schroeder, 1996).
During the transformation process, the reduced ameloblasts change their
morphology from short columnar to flattened cells that are oriented parallel to
the enamel surface. Also, the cells external to the reduced ameloblasts undergo
a structural change with their desmosomes and basal lamina adjacent to enamel
surface. This is the primary epithelial attachment.

These transformed ameloblasts migrate in a coronal
direction, are exfoliated at the bottom of the sulcus, and
eventually are replaced by the cells external to the
reduced/transformed ameloblasts (Schroeder, 1996) .

It has been proposed that the junctional epithelium, 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 gingival epithelium
(TenCate, 1996).
This holds true, at least, for de novo formation of the junctional epithelium
following gingivectomy (Salonen,1986; Salonen et al., 1989). However, basal
epithelial cells other than those of oral gingival origin may also regenerate a
junctional epithelium (Listgarten, 1967, 1972b; Braga and Squier, 1980; Freeman,
1981).

A process of transformation takes place where the reduced enamel
epithelium gradually becomes junctional epithelium.
Junctional epithelium is attached to the tooth surface (epithelial
attachment) by means of an internal basal lamina & to the gingival
connective tissue by an external basal lamina that has the same
structure as other epithelial-connective tissue attachments.
The interface between junctional epithelium and the tooth surface
forms the secondary epithelial attachment made up of epithelial
attachment lamina and the hemidesmosomes.

The epithelial cells are referred to as the junctional epithelium, while
epithelial attachment refers to the zone of attachment.

STRUCTURE OF JUNCTIONAL EPITHELIUM
ANATOMICALASPECTS
The junctional epithelium is part of the marginal 'free' gingiva, forms a
collar peripheral to the cervical region of the tooth, and hence is not visible
intra-orally.
In the interproximal area, the junctional epithelia adjacent to neighboring
teeth fuse to form the epithelial lining of the interdental col.
The coronal termination of the junctional epithelium is a free surface and is
located either at the bottom of the sulcus, at the gingival margin, or at the
interdental col area.
Under pristine conditions, the epithelial seal extends from CEJ to the
gingival margin, averaging about 2mm in height. (GARGINLO et al,1961)
Length of J.E. may range from 0.25-1.35mm. (CARRANZA,10th edition)

The Epithelial Attachment
The junctional epithelium faces both the gingival connective tissue
(i.e., the lamina propria of the gingiva) and the tooth surface.
A basement membrane, sometimes referred to as 'the external basal
lamina' (Schroeder, 1996), is interposed between the basal cells of the
junctional epithelium and the gingiva connective tissue, a basal lamina
(also known as the internal basal lamina) forms part of the interfacial
matrix between the tooth-facing junctional epithelial cells (also known
as DAT cells;) and the tooth surface .
At the apical end of the junctional epithelium, the basal lamina is
continuous with the basement membrane.

While the external basement membrane of the junctional epithelium
resembles, in its structure and composition, other basement membranes
that are interposed between an epithelium and a connective tissue, the
internal basal lamina has distinctively different structural and molecular
characteristics.
It lacks most of the common basement membrane components such as
collagen types IV and VII, most laminin isoforms, perlecan, and a lamina
fibroreticularis (Salonen and Santti, 1985; Kogaya et al., 1989; Sawada et
al., 1990; Salonen et al., 1991; Oyarzun-Droguett, 1992; Hormia et al.,
2001.

Laminin-5, appears to be expressed in the internal basal lamina but
not in the external basement membrane of the junctional epithelium,
at least in rats (Oksonen et al., 2001).
Thus, the internal basal lamina of the junctional epithelium has its
own characteristics and cannot be regarded as a basement membrane
in the true sense.
The basal lamina together with hemidesmosomes (Listgarten,
1966, 1972a; Schroeder, 1969) forms the interface between the tooth
surface and the junctional epithelium and is named 'epithelia
attachment' (Schroeder and Listgarten, 1977).

The attachment of the junctional epithelium 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 unit, referred to as the dentogingival unit.

DYNAMIC ASPECT JUNCTIONAL EPITHELIUM
The cell and extracellular dynamics of the junctional epithelium
are essential for its protective and regenerative functions. The
junctional epithelium in primates is known for its high cellular
turnover (Demetriou and Ramfjord, 1972).
Cell mitosis occurs in the basal and possibly also in some DAT
cells (Salonen, 1994), and it migrate in the coronal direction, where
they desquamate (Salonen, 1994), exfoliation of daughter cells takes
place at the free surface of the junctional epithelium (i.e., at the
bottom of the sulcus and the interdental col).

Thus, junctional epithelial cells migrate in the coronal direction toward
the free surface, where they desquamate. As 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 (Schroeder 1969) and, exfoliation must occur at an
extremely high rate (Löe and Karring, 1969; Listgarten, 1972b).

EXPRESSION OF VARIOUS MOLECULES AND THEIR FUNCTION
Junctional epithelium 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.
Junctional epithelial cells exhibit rapid turnover, which contributes
to the host–parasite equilibrium and rapid repair of damaged
tissue.(Robert J Genco 1996)

Cells of the JE have endocytic capacity equal to that of macrophages
and neutrophils,and that this activity might be protective in
nature.(Cho.Garant.2000)
Funnelling of junctional epithelial cells towards the sulcus hinder
bacterial colonization
Active antimicrobial substances are produced in junctional epithelial
cells. These include defensins and lysosomal enzymes.

There are distinct differences between the oral sulcular
epithelium, the oral epithelium and the junctional epithelium:
 The size of the cells in the junctional epithelium is, relative to the
tissue volume, larger than in the oral epithelium.
 The intercellular space in the junctional epithelium is, relative to the
tissue volume, comparatively wider than in the oral epithelium
 The number of desmosomes is smaller in the junctional epithelium
than in the oral epithelium.

Renewal of Gingival Epithelium
The oral epithelium undergoes continuous renewal. Its thickness is
maintained by a balance between new cell formation in the basal and spinous
layers and the shedding of old cells at the surface.
The mitotic activity exhibits a 24-hour periodicity, with highest and lowest
rates occurring in the morning and evening, respectively(International
Association for Dental Research,1967).
The mitotic rate is higher in non-keratinized areas and is increased in
gingivitis, without significant gender differences. Opinions differ as to
whether the mitotic rate is increased(Loe H,Karring A,1969) or
decreased(Barakat NJ,1969)" with age

The following have been reported as turnover times for different
areas of the oral epithelium in experimental animals: palate, tongue,
and cheek, 5 to 6 days; gingiva, 10 to 12 days, with the same or more
time required with age; and junctional epithelium, 1 to 6 days.'(Beagrie
GS,Skougaard MR,1962)

Gingival Connective Tissue
The predominant tissue component of the gingiva is the connective
tissue known as the lamina propria and consists of two layers:
1) a papillary layer subjacent to the epithelium, which consists of
papillary projections between the epithelial rete pegs, and
2) a reticular layer contiguous with the periosteum of the alveolar bone.
Connective tissue has a cellular and an extracellular compartment
composed of fibers and ground substance

The major components of the connective tissue are :
 Collagen fibers(around 60% of connective tissue volume)
Fibroblasts (around 5%),
Vessels and nerves which are embedded in an amorphous ground substance matrix
(Around 35%).
Cells
The different types of cell present in the connective tissue are:
(1) Fibroblasts,
(2) Mast cells,
(3) Macrophages and histiocytes
(4) Inflammatory cells (plasma cells ,lymphocytes ,neutrophils)
(5) Adipose cells and eosinophil (rarely)

Fibroblast
The fibroblast is the most predominant connective tissue cell
(65% of the total cell population).
Numerous fibroblasts are found between the fiber bundles.

Mast cells
The mast caell is responsible for the production of certain
components of the matrix,
These cells, which are often located near vascular elements,
exhibit a characteristic histological picture consisting of large
cytoplasmic granules.
The granule are electron-dense, and they contain substance
(such as histamine and heparin) known to elicit inflammation .
The golgi complex is well developed, while granular
endoplasmic reticulum structures are scarce.

Macrophages and histiocytes
Fixed macrophages and histiocytes are present in the gingival
connective tissue a components of the mononuclear phagocyte
system (reticuloendothelial system) and are derived from blood
monocytes.
The nucleus is characterized by numerous invaginations of
varying size.
A zone of electrondense chromatin condensations can be seen
along th periphery of the nucleus.
The Golgi complex (G) is well developed and numerous vesicles
(V) of varyin size are present in the cytoplasm

Inflammatory cells
In clinically normal gingiva, small foci of plasma cell and
lymphocytes are found in the connective tissue near the base of the
sulcus .
Neutrophils can be seen in relatively high numbers in both the
gingival connective tissue and the sulcus.
These inflammatory cells usually are present in small amounts in
clinically normal gingiva

Fibers
The connective tissue fibers are produced by the fibroblasts and can
be divided into: (1) collagen fibers, (2) reticulin fibers, (3) oxytalan
fibers and (4) elastic fibers.
The collagen fibers predominate in the gingival connective tissue and
constitute the most essential components of the periodontium.
Electronmicrograph shows cross- and longitudinal sections of
collagen fibers. The collagen fibers have a characteristic cross-banding
with a periodicity of 640 A between the individual dark bands.
Type I collagen is the main collagen species in all layers of gingival
connective tissues .

Type I collagen is preferentially organized into denser fibrils in the
lamina propria.
Type III collagen appears to be preferentially localized as thinner
fibers in a reticular pattern near the basement membrane at the
epithelial junction
Immunostaining studies have revealed that type V collagen (accounts
for <1% of total collagen) has a parallel filamentous pattern, and this
collagen appears to coat dense fibers composed of type I and III
collagens .
The gingival connective tissue contains type VI collagen as well,
which is present in diffuse microfibrillar pattern

Reticulin fibers (type IV collagen )— (argyrophilic reticulum fiber)
branches between the collagen type I bundles and is continuous with
fibers of the basement membrane and blood vessel walls.
The elastic fiber system is composed of oxytalan, elaunin, and elastin
fibers distributed among collagen fibers .

Gingival Fibres
The connective tissue of the marginal gingiva is densely collagenous,
containing a prominent system of collagen fiber bundles called the gingival
fibers. They consist of type I collagen.
The gingival fibers have the following functions:
1. To brace the marginal gingiva firmly against the tooth
2. To provide the rigidity necessary to withstand the forces of mastication
without being deflected away from the tooth surface
3. To unite the free marginal gingiva with the cementum of the root and the
adjacent attached gingival and this unit is called as dentogingival unit.

CORRELATION OF CLINICALAND
MICROSCOPIC FEATURES
 COLOR: colour of the attached and marginal gingiva is generally
described as “coral pink” and is produced by the vascular supply, the
thickness and degree of keratinisation of the epithelium, and the presence
of pigment containing cells.
 Colour varies among different persons and appears to be correlated with
the cutaneous pigmentation. Its higher in blond individuals with fair
complexion than in swarthy, dark haired individuals
 The attached gingiva is demarcated from adjacent alveolar mucosa on
the buccal aspect by a clearly defined mucogingival line.
 The lveolar mucosa is red, smooth, and shiny rather than pink and
stippled.
 SIZE: the size of the gingiva corresponds to the sum total of the bulk of
cellular and intercellular elements and their vascular supply. Alteration in
size is a common feature of gingival disease

 CONTOUR: Contour varies considerably and depends on the shape of the
teeth and their alignment in the arch, the location and size of the area of
proximal contact, and dimensions of the facial and lingual gingival embrasures.
 Marginal gingiva envelops the teeth in collar like fashion and follows a
scalloped outline on the facial and lingual surfaces.
 It forms straight line along the teeth with relatively flat surfaces. On teeth
with pronounced mesiodistal convexity or teeth in labial version, the normal
arcuate contour is accentuated, and the gingiva is located farther apically.
 On teeth in lingual version, the gingiva is horizontal and thickened.
 SHAPE: Shape of interdental gingiva is governed by the contour of the
proximal tooth surfaces and the location and shape of gingival embrasures.
 When the proximal surfaces of the crown are relatively flat facioingually, the
roots are close together, the interdental bone is thin mesiodistally, and the
gingival embrasures and interdental gingiva are narrow mesiodistally.

 CONSITENCY: the gingiva is firm and resilient and, with the exception of
movable free margin, tightly bound to the underlying bone.
 Collagenous nature of lamina propria and its contiguity with the
mucoperiosteum of the alveolar bone determine the firmness of the attached
gingiva
 The gingival fibres contribute to the firmness of the firmness of the gingival
margin.
 SURFACE TEXTURE: Gingiva presents a textured surface similar to an
orange peel and is referred to as being stippled. Stippling is best viewed by
drying the gingiva.
 The attached gingiva is stippled; marginal gingiva is not. Central portion of
interdental papilla is usually stippled, but the marginal borders are smooth.
 Stippling varies with age. Its absent in infancy, appears in some children at
about 5 years of age, increases until adulthood, and frequently begins to
disappear in old age.

 POSITION: Position of the gingiva refers to the level at which the gingival
margin is attached to the tooth. When the tooth erupts into the oral cavity, the
margin and the sulcus are at the tip of the crown; as the eruption progresses, they are
seen closer to the root
 During this eruption process, junctional epithelium, oral epithelium, reduced
enamel epithelium undergo extensive alterations and remodelling while maintaining
the shallow physiologic depth of the sulcus.

References :
 Clinical periodontology and implant dentistry,5th edition by Jan
lindhe, Niklalaus P.Lang,Thorkild karring.
 Carranza’s clinical periodontology,10th edition.
 Periodontal connective tissues by P.Mark Bartold1
Clinical periodontology and implant dentistry,5th edition by Jane lindhe,
Niklalaus P.Lang,Thorkild karring.
 Gingival biotype: a review,Zeinab Rezaei Esfahrood, DDS, MS n
Mahdi Kadkhodazadeh, DDS, MS n Mohammad Reza Talebi Ardakani,
DDS, MS
 Development and general structure of the periodontium
,Periodontology 2000, Vol. 24, 2000, 9–27

 Surface ultra structure of human gingival, J. Periodontal Res. 13:
367-371, 1978.
 Orban’s Oral Histology and Embryology, 13th edition.
 Richard TenCate,.Oral Histology- Development, structure
& Function. 6th Ed

Ultrastructure of gingiva

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Ultrastructure of gingiva