4. • Oral mucosa-three zones:
o The gingiva and the covering of the hard
palate:masticatory mucosa
o The dorsum of the tongue,covered by
specialized mucosa
o The oral mucous membrane lining the
remainder of the oral cavity.
5. DEFINITION
The part of oral mucosa that covers the alveolar
processes of jaws and surrounds the neck of the teeth.
CARRANZA(11th )edition
It is that part of masticatory mucosa covering alveolar
processes and cervical portion of teeth.
LINDHE(5th)edition
6. • FUNCTIONS:
As the gingiva represents both the masticatory mucosa
as well as the most peripheral part of the periodontium,its
functions are two fold.
As part of the oral mucosa:
it protects the suppoting tissues from the oral
enviroment.
a) As part of oral mucosa,it is subjected to friction and
pressure in the masticatory process.Its densely
collagenous lamina propia,peripheral sensory innervation
and keratinization help in the adaptation to these physical
requirements.
b) It is mucostable tissues because of its firmness,scalloped
contour,close adaptation and attachment to the
underlying structures.
c) Gingival tissues fulfil the functions of sensitivity and
resistance.
7. As part of the periodontium
The gingiva exhibits functional properties:
a) It ensures dental arch linkage and controls the
positioning of teeth in the horizontal plane by
means of its supra-alveolar fibre
apparatus.These fibres along with those of PDL
secure teeth against rotational forces .
b) It maintains gingival and periodontal health by
means of various defence mechanism operating
within the gingival tissues.
8. • This peripheral defence action of gingiva has two
arms:
1. The humoral arm which represents the generation
of gingival fluid.
2. The cellular arm which represents the continuous
irrigation of neutriphilic granulocytes via the
junctional epithelium.
Both these arms keep a 24 hour watch on the
periodontal health.
9. Developmental Aspects
• To our knowledge,no study exists describing the pre
and post natal development of the gingiva in man and
animal species prior to tooth eruption.
• According to schroeder,the shape,topographical
distribution and width of the gingiva are functions of
the presence and position of erupted teeth.
• He also says that,there are reason to assume that the
gingival tissues exist and develop as a site specific
portion of the oral mucous membrane prior to the
eruption of deciduous teeth.Thereafter,the gingiva
although increasing size serves both deciduous and
permanent teeth.
10. DEVELOPMENT
• The development of the periodontal tissues occurs during the development
and formation of teeth.
• The neural crest cells form a band of ectomesenchyme beneath the
epithelium of the stomatodeum(the primitive oral cavity)
• The primary epithelial band
• The ectomesenchyme takes dominant role in the development and
formation of dental lamina
• A series of processes are initiated(bud stage,cap stage,bell stage with root
development)which result in the formation of a tooth and its surrounding
periodontal tissues.
• The tissue components of the dento-gingival region achieved their final
structural charecteristics in conjuction with the eruption of tooth.
Vestibular
lamina
Dental
lamina
11. • Cap stage of tooth
development.the epithelial
enamel organ sits over a mass
of ectomesenchymal cells,the
dental papilla that extends
around the rim of the enamel
organ to form the dental
follicle.
12. DEVELOPMENT OF GINGIVAL SULCUS
• After enamel formation completes,the
crown is covered with reduced enamel
epithelium(REE),which terminates at
CEJ.the basal lamina (EAL)lies in contact
with enamel directly.
• When the tooth penetrates oral
mucosa,REE fuses with oral epithelium.
• Shortly the epithelial mass at the tip of
crown degerates,resulting exposure of
crown in oral cavity.
• With the tooth eruption,this united
epithelium condenses along the crown
,and the ameloblasts from the inner layer
of REE become squamous cell with time.
13. • The gingival sulcus is formed
when tooth erupts into oral
cavity.
• Gradually this united epithelium
transforms into junctional
epithelium,which occurs in
apical direction.
• JE is continually self renewing
tissue.The regenerating
epithelum moves coronally
towards the gingival
sulcus,where they are shed.
• The migrating daughter cells
provide continuous attachments.
14. • Anatomically,it has been divided into:
MARGINAL gingiva
ATTACHED gingiva
INTERDENTAL gingiva
15. MARGINAL GINGIVA
•The marginal or unattached
gingiva is the terminal edge or
border of the gingiva surronnding
the teeth in collar like fashion.
•It is demarcated from the adjacent
attached gingiva by a shallow linear
depression,the free gingival
groove,in about 50% cases.
•Usually 1 mm wide
•It forms the soft tissue wall of
gingival sulcas
•Its apicoronal and mesiodistal
dimensions varied between 0.06
&0.96mm
16. FREE GINGIVAL GROOVE
• FORMED BY FUNCTIONAL
FOLDING OF FREE
GINGIVAL MARGIN
DURING MASTICATION
• RUNS PARALLEL TO THE
MARGIN OF GINGIVA AT A
DISTANCE OF 0.5 TO 1.5
MM,NOT ALWAYS
VISIBLE.
17. ATTACHED GINGIVA
• The attached gingiva is
continuous with the marginal
gingiva.
• It is firm,resilient and tightly
bound to the underlying
periosteum of alveolar bone.
• The facial aspect of the
attached gingiva extends to
the relatively loose and
movable alveolar mucosa,from
which it is demarcated by the
mucogingival junction.
18. GINGIVAL SULCUS
o It is a shallow crevice or
space around the tooth
o Bounded by the surface of
the tooth on one side and
the epithelial linning the
free margin of the gingiva
on the other side
o It is v-shaped and barely
permits the entrance of
periodontal probe
o The probing deapth of a
clinically normal gingival
sulcus in humans is 2-3 mm
19. • Width of attached gingiva:
In the incisor region :
3.5-4.5mm in maxilla
3.3-3.9mm in mandible
In the posterior region:
1.9mm in maxilla
1.8mm in mandible
20. Width of keratinized gingiva
Width of attach gingiva
Distance between the mucogingival
junction &the projection on the external
surface of the bottom of gingival sulcus
21. MUCOGINGIVAL JUNCTION
• The facial aspect of attached
gingiva extends to the relatively
loose and movable alveolar
mucosa(red) and is demarcated
by the mucogingival junction.
• In the palatal aspect it is
continuous with palatal mucosa
and on the lingual aspect of the
mandible.it terminates at the
junction of the lingual alveolar
mucosa
• Mucogingival junction remains
stationary throughout life
22. INTERDENTAL GINGIVA
• Occupies gingival
embrassure,which is the
interproximal space beneath the
area of tooth contact.
• The interdental gingiva can be
pyramidal or hava a “col” shape.
• In the pyramid shape ,the tip
papilla is located immediately
beneath the contact point;the
col shape presents a valley like
depression that connects a
facial and lingual papilla and
conforms to the shape of the
interproximal contact.
23. • The shape of the gingiva in a given interdental
space depends on the :
Contact point between the two adjoining teeth
The presence or absence of some degree of recession.
24. • If a diastema is present,the
gingiva is firmly bound
over the interdental bone
and forms a
smooth,rounded surface
without interdental
papillae.
26. • Stratified squamous epithelium
predominantly cellular in nature
• Central core of connective tissue
less cellular and composed primarily of collagen
fibers and ground substance
27. GINGIVAL EPITHELIUM
• The epithelium covering the
free gingiva may be
diffarentiated as follows:
ORAL EPITHELIUM:which faces
the oral cavity
SULCULAR EPITHELIUM:which
faces the tooth without being
in contact with the tooth
surface.
JUNCTIONAL
EPITHELIUM:which provides
the contact between the
gingiva and the tooth.
28. ORAL EPITHELIUM
The epithelium forms the primary barrier
between the oral enviroment and deeper
tissue.
It consist of two cell populations:
Progenitor population-the function is to
divide and provide new cells
Maturing population-the cells continually
undergo a process of differentiation or
maturation with the formation of a
protective surface layer.
30. DIFFERENCE BETWEEN KERATINIZED
&NONKARATINIZED EPITHELIM
KERATINIZED
BASAL
• Cuboidal,columner cells containing bundles
of tonofibrils&other cell organelles,site of
most cell divisions.
PRICKLE
• Larger ovoid cells containing conspicuous
tonofibril bundles membrane coating
granules appear in upper part of this layer.
GRANULAR
• Flattened cells containing conspicuous
keratohyline granules associated with
tonofibrils;membrane coating granules fuse
with cell membrane in upper part;there is
also internal membrane thickening
KERATINIZED
• Extremely flattened&dehydrated cells in
which all organanelles have been lost;cells
filled with packed fibrilar material;when
pyknotic nuclei are retained there is
parakeratinization.
NON- KERATINIZED
BASAL
• Cuboidal columnar cells containing
separate tonofilaments &other cell
ornanelles;site of most cell divisions
PRICKLE
• Larger ovoid cells containing dispersed
tonofilaments;MCG appear in upper of
layer;filaments become numerous
INTERMEDIATE
• Slightly flattened cells containing many
dispersed tonofilaments&glycogen.
SUPERFICIAL
• Slightly flattened cells with dispersed
filaments&glygen;fewer orgaelles
present but nuclei persist.
32. ORTHO-
KERATINIZED
PARA-KERATINIZED
NON-
KERATINIZED
No nuclei in the stratum
corneum and presents a
well-defined stratum
granulosum
Stratum corneum retains
pyknotic nuclei
Keratohyalin granules are
dispersed,not giving rise to a
stratum granulosum
Neither granulosum
nor corneum strata
and superficial cells
have viable nuclei
33. General Aspect
• The gingival epithelium is a
keratinized,stratified,squamous epithelium which
on the basis of the degree to which the keratin
producing cells are differentiated can be divided
into the following cell layers:
Basal layer(stratum basale or stratum
germinativum)
Spinous cell layer(stratum spinosum)
Granular cell layer(stratum granulosum)
Keratinized cell layer(stratum corneum)
34. Basal layer(stratum basale,stratum
germinativum)
• The 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.
• Therefore ,this layers also termed
stratum germinativum and can be
considered the proginator cell
compartment of the epithelium.
35. • When two daughter cells (D) have
been formed by cell division,an
adjacent”older”basal cell(OB) is
pushed into the spinous cell layer
and starts,as a keratinocyte,to
traverse the epithelium.
• It takes approximately 1 month for
a keratinocyte to reach the outer
epithelial surface,where it
becomes shed from the stratum
corneum.
• Within a given time,the no.of cells
which divide in the basal layer
equals the no. of cells which
become shed from the surface.
36. • Immediately beneath the basal cell an electron lucent
zone can be seen which is called lamina lucida.
• Beneath the lamina lucida an electron dense zone of
approximately the same thickness can be observed.This
zone is called lamina densa.
• From the lamina densa so called anchoring fibres(abuot 1
µm) project in a fan shaped fashion into the connective
tissue.
• The cell membrane of the epithelial cells facing the lamina
lucida harbours a no. of electron dense,thicker zones
appearing at various intervals along the cell
membrane.Thease structures are called hemidesmosomes.
• The cytoplasmic tonofilaments in the cell
converge,towards such hemidesmosomes.
• The hemidesmosomes are involved in the attachment of
the epithelium to the underlying basement membrane.
37.
38. Stratum Spinosum (Prickle cell layer)
• 10-20 layers
• Large ,polyhedral cells
• Short cytoplasmic processes
resembling spines
• Prickly appearance
• Cohesion:Desmosome
located between the
cytoplasmic processes of
adjacent cells.
39. • Desmosome may be considered to
consist of two adjoining
hemidesmosomes separated by a zone
containing electron-dense granulated
material(GM).
• Thus a desmosome comprises the
follwing structural components:
1. The outer leaflets(OL) of the cell
membrane of two adjoining cells
2. The thick inner leaflets(IL) of the cell
membranes and
3. The attachment plaques(AP),which
represent granular and fibrillar
material in the cytoplasm.
40. Stratum Granulosum
• The cytoplasm of these cells characteristically
displays KERATOHYALINE GRANULES(arrows)
that have been associated with KERATIN
FORMATION.
KERATINOHYALINE GRANULES:small granules
that stain with acid dyes such as
hematoxyline.thus basophilic in
nature.ODLAND BODIES are present.
41. KERATOHYALINE GRANULES
Irregular in shape
Probably synthesized by ribosomes
Associated with tonofibrils
Facilitate the aggregation and formation of crosslinks
between the cytokeratin filaments of the keratinized layer
For this reason protein making the bulk of these granules is
called FILAGGRIN.
KERATINOHYALINE
GRANULES BASOPHILIC UNDER LIGHT
MICROSCOPE
ELECTRON DENSE
STRUCTURES
ELECTRON
MICROSCOPE
42. Stratum Corneum
• Filled with keratin
• The entire apparatus for protein synthesis energy
production,i.e. the nucleus,the mitochondria,the
endoplasmic reticulum and the Golgi complex is lost.
• In a parakeratinised epithelium,however, the cells of
the stratum corneum contain remnants of nuclei.
• Acidophilic-red staining with hematoxylin and eosin.
46. Keratinocyte/Corneocyte
1. Cells containing tonofilaments.
2. In keratinized epithelium tonofilaments are arranged as
tonofibrils
3. In nonkeratinized epithelium this tonofibrils arrangement is not
present.
4. Keratin proteins contains different molecular weights and
isoelectric points
5. Basal cells synthesize low molecular weight keratin K19(40 kD)
6. Corneal cells express high molecular weight keratin K1(68kD)
7. Other proteins are keratolinin and involucrin(envelop)and
filaggrin(matrix)
8. Demosomes are present between keratinocytes.some time
tight junctions are seen.
9. Active cytolasmic organelles are seen in basal layers vice versa
for superficial layer.
10. Spinosal layer cells contain keratinosomes or odland bodies.
47. Keratinocytes
• The main function is to protect the deep
structure,while allowing a selective
interchange with the oral environment.
This is achieved by
o Proliferation
o Differentiation
48. • The man morphologic
changes are:
• Progressive flattening of
the cells with an increase
prevalence of
tonofilaments.
• Intercellular junctions
coupled to production of
keratohyaline granules
• Disappearance of nucleus
Schroder 1981
M-mitochondria,G-golgi bodies,E-
endoplasmic reticulam,D-
desmosomes,F-tonofilaments,K-
keratohyalin granules
49. Keratinisation
• The keratin proteins are composed of different
polypeptide subunits characterised by their
isoelectric points and molecular weights.
• They are numbered in a sequence contrary to
their molecular weight.
• Generally ,basal cells begin synthesizing lower
molecular weight keratins,such as K19(40kD),and
express other higher molecular weight keratins as
they migrate to the surface.
• K1 keratin polypeptide(68 kD) is the main
component of stratum corneum.
50. • Other proteins:
• Keratolinin
• Involucrin
• Filaggrin
• In the sudden transition to the horny layer, the kerato hyalin
granules disappear and give rise to filaggrin which forms the
matrix of the most differentiated epithelial cell,the
corneocyte.
• In the fully differentiated state,the corneocytes are mainly
formed by bundles of keratin tonofilaments embsdded in an
amorphous metrix of filaggrin and are surrounded by a
resistant envelope under the cell membrane.
Precursors of chemical resistant structure,located
below the cell membrane-envelop
Precursors packed in keratohyaline granules
51. According to histochemical
demonstration
In deeper strata
• Cytoplasmic organelle
concentration varies among
different epithelial strata.
• Mitochondria are more
numerous in deeper strata and
decrease toward the surface of
the cell.
• Succinic dehydrogenase
• Nicotineamide-adenine
dinucleotide
• Cytochrome oxidase
Revels more active Tricarboxylic
Cycle,in which the proximity of
blood supply facilitates energy
production through aerobic
glycolysis
52. Activity towards surface:
• Pentose shunt Glucose-6-phosphatase
Ribonucleic acid(RNA)
Synthesis of keratinization proteins
53. • The uppermost cells of the stratum spinosum
contain numerous dense granules,keratinosomes
or odland bodies(modified lysosomes)
• Acid phosphatase:enzyme involved in the
destruction of organelle membranes.
• It occurs suddenly between the granulosum and
corneum strata and during the intercellular
cementation of cornified cells.
• Therefore,it is closely related to degree of
keratinization.
55. Melanocytes
• Dendritic cell
• Located in the basal and spinous
layer of gingival epithelium
• Synthesize melanin in organelle
called premelanosomes or
melanosomes. Pigmented gingiva
showing melanocytes(M)
in the basal epithelial
layer and
melanophores(C) in the
connective tissue
tyrosine dihydroxyphenylalanine melanine Melanophore/mel
-anophages
56. Langerhans cells
• Dendritic cells located among
keratinocytes at all suprabasal
levels.
• They belong to the mononuclear
phagocytes system(reticulo-
endothelial system) as modified
moocytes derived from bone
marrow.
• They contain elongated granules
and are considered macrophages
with possible antigenic properties.
Human gingival
epithelium,oral
aspect.Immunoperoxidase
technique showing
Langerhans cells.
57. • They have an important role in immune reaction
as antigen-presenting cells for lymphocytes.
• They contain g-specific granules(Birbeck’s
granules) and have marked adenosine
triphosphate activity.
• They found in oral epithelium of normal gingiva
and in smaller amounts in sulcular
epithelium;they are probably absent from
junctional epithelium of normal gingiva.
58. Merkel cells
• Located in the deeper layer of epithelium.
• Harbours nerve endings.
• Connected to adjacent cells by desmosomes.
• Act as a tactile receptors.
59. Inflammatory cells
• Clinical normal areas of mucosa
• lymphocytes: most frequent
associated with langerhans cells
• Polymorphonuclear leukocytes
• Mast cells
60. Extracellular Matrix
• Since the epithelia of the gingiva are composed primarily of
cells in close apposition,there is very little extracellular
space.
• Extracellular matrix contains:
Glycoproteins,lipids,water
Proteoglycans:Hyaluronan,decorin,syndecan
CD44 antigen-being identified on cell surface
Cell adhesion molecules:ICAM-1,BETA 1 integrin family.
• Extracellular matrix serves the purpose of:
Cell adhesion
Adhesion to tooth surface & basement membrane
Diffusion of water,nutrients&toxic materials
61. REFERENCE
• Clinical periodontology,11th edition-Carranza.
• Oral Histology,Development,structures and
function-A.R.Tencate,8th edition
• Oral Anatomy,Histology and Embryology-
Berkovitz 4th edition.
• Clinical periodontology and Implant Dentistry-
Jan Lindhe,5th edition.
