1. Jeena Sara Paul 15th Jan 2009
Ist year MDS 9.00 AM
Christian Dental College
Ludhiana

2.  The moist lining of the oral cavity that is in
continuation with the exterior surface of skin
on one end and oesophagus on the other end
is called the oral mucosa or oral mucous
membrane.

3.  It is protective mechanically against both compressive and shearing
forces.
 It provides a barrier to microorganisms , toxins and various antigens.
 It has a role in immunological defence, both humoral and cell-
mediated.
 Minor glands within the oral mucosa provide lubrication and
buffering as well as secretion of some antibodies.
 The mucosa is richly innervated, providing input for
touch, proprioception, pain and taste.
 Reflexes such as gagging, retching and salivating are initiated by
receptors in the oral mucosa.

4.  Primitive oral cavity develops by fusion of
embryonic stomatodeum with foregut after
rupture of buccopharyngeal membrane at 26
days IU
 Structures from branchial arches like tongue
epiglottis and pharynx covered by epithelium
derived from endoderm
 Epithelium covering palate cheeks and gingivae
of ectodermal origin

5.  5-6 weeks: 2 layers of cells have formed lining oral
cavity
 8 weeks: thickening in area of vestibular dental lamina
complex, extracellular reticular fibres accumulate
 10-14 wks: cellular degeneration forming oral
vestibule
 8-11 wks Palatal shelves elevate and close. Capillary
buds and collagen fibres detected
 At this time morphology of future mouth is apparent

6.  7 wks: circumvallate and foliate papillae appear
followed by fungiform .
 10 wks: filiform papillae appear
 10-12 wks: future lining and masticatory mucosa
stratification of epithelium and different morphology
 Areas destined to become keratinised have darkly
staining columnar basal epithelium
 Epithelial cells in areas of future lining mucosa retain
cuboidal cells

7.  13-20 wks: all oral epithelia thicken with
appearance of sparse keratohyalin granules
 Melanocytes and langerhans cells appear
 Surface layers show parakeratinisation;
orthokeratosis occurs only after eruption of
teeth post-natally
 17-20 wks: completely formed with appearance
of elastic fibres in the ectomesenchyme

8.  The oral cavity consists of 2 parts: outer
vestibule (bounded by lips and cheek) oral cavity
proper (separated by alveolus bearing teeth and
gingivae).
 Superiorly: hard and soft palate
 Inferiorly: floor of mouth, base of tongue
 Posteriorly: pillars of fauces, tonsils

10. 3 main
types of
mucosa
Masticatory Lining Specialized
identified
mucosa Mucosa Mucosa
according
(60%) (25%) (15%)
to their
primary
function:

11.  Although continuous with skin, oral mucosa
differs in a number of ways.
 Colour: Oral mucosa is more deeply
coloured, most obviously at the lips.
 Concentration and state of dilatation of blood
vessels.
 Thickness of epithelium
 Degree of keratinisation
 Amount of melanin pigment

12.  Moist surface and absence of appendages.
 Glandular component of oral mucosa
represented by minor salivary glands. Occasional
sebaceous glands in upper lip and buccal
mucosa: Fordyce's spots.
 Smoother surface and fewer wrinkles.
 Papillae on dorsum of tongue.
 Transverse ridges of palate

13.  Stratified squamous epithelium: oral epithelium
(epidermis)
 Connective tissue layer: Lamina Propria (dermis)
 Interface: Upward projections of connective
tissue- Connective tissue papillae interdigitate
with epithelial ridges- Rete ridges or rete pegs
 Typical haematoxylin-eosin stain shows this
interface as a structure less layer about 1-2
microns thick- basement membrane.

14.  The junction between oral epithelium and lamina propria
is obvious, unlike that between oral mucosa and
underlying tissue.
 Oral mucosa has no muscularis mucosae.
 In cheeks, lips and parts of hard palate, a layer of loose
fatty glandular tissue containing vessels and nerves
supplying the mucosa separates the oral mucosa from
underlying bone or muscle: Submucosa
 In gingiva and parts of hard palate, oral mucosa directly
attached to underlying bone. This provides a firm inelastic
attachment: Mucoperiosteum

15.  Minor salivary glands in submucosa
 Sebaceous glands in lamina propria produce sebum said to lubricate the
surface of the mucosa. This might actually be an embryologic anomaly.
 Nodules of lymphoid tissue are present in various areas consisting of
crypts formed by invaginations of epithelium into lamina propria.
 Capillaries carry adhesion molecules like:
 Endothelial cell leukocyte adhesion molecule
 Intercellular adhesion molecule
 Vascular cell adhesion molecule
 These facilitate trafficking of leukocytes (lymphocytes and plasma cells)
from blood.
 Found as lingual, palatine and pharyngeal tonsils forming Waldeyers ring.
 Small nodules also in soft palate, ventral surface of tongue, floor of
mouth.

16.  Constitutes primary barrier between oral environment and deeper
tissues.
 The oral epithelium is a stratified squamous epithelium consisting
of cells tightly attached to each other and arranged in a number of
distinct strata.
 Maintains its structural integrity by a process of continuous cell
renewal.
 Cells produced by mitotic divisions in deepest layers replace those
that are shed.
 Thus there are 2 populations of cells:
 A progenitor population
 A maturing population

19.  In thin epithelia, progenitor cells seen in basal layer
 In thicker epithelia, seen in lower 2-3 cell layers
 Studies on epidermis and oral epithelium indicate that progenitor
compartment consists of 2 functionally distinct subpopulations:
 A small population of slowly cycling stem cells: Retains
proliferative potential
 A larger population of amplifying cells: increases number of cells
available for maturation
 Turnover time: time taken for a cell to divide and pass through the
entire thickness of epithelium.
 52-75 days in skin
 4-14 days in gut
 41-57 days in gingiva
 25 days in cheek

20. OUTER SURFACE OF GINGIVA.
TEN DAYS AFTER LABELLING
PROLIFERATING BASAL CELLS
WITH H3 THYMIDINE
MANY OF THE CELLS HAVE
PASSED TO THE OUTER SURFACE
AND BECOMED KERATINISED
.CELL TURNOVER IS 10 TO 12
DAYS.

21. Mitotic activity affected
by:
Epidermal growth factor
Keratinocyte growth factor
Interleukin 1
Transforming growth factors
Time of the day
Stress
Inflammation

22.  2 main patterns: keratinisation and nonkeratinization
 Keratinisation:
 Inflexible, tough, resistant to abrasion and tightly bound
to lamina propria
 The mucosal surface results from formation of a surface
layer of keratin and process of maturation is called
keratinisation or cornification.
 Shows 4 stratae:
 Stratum basale
 Stratum spinosum
 Stratum granulosum
 Stratum corneum

23.  Basal layer- layer of cuboidal or columnar cells adjacent to
basement membrane
 Stratum spinosum- several rows of larger elliptical or spherical
cells also known as prickle cell layer. Cells aligned such that
they remain in contact only at points known as desmosomes
or intercellular bridges
 Stratum granulosum- Larger flattened cells with small
granules that stain intensely with acidic dyes.
 Stratum corneum- The surface layer composed of flat cells
called squames that stain bright pink with eosin and has no
nuclei. The pattern of maturation of these cells is called
orthokeratinization
 Parakeratinisation is a variation of keratinisation seen in
masticatory mucosa. The surface layer stains for keratin but
pyknotic nuclei are retained in some or all squames.
Keratohyalin granules present but fewer granules

25.  Non keratinisation
 Lips, buccal mucosa, alveolar mucosa, soft
palate, underside of tongue, floor of mouth
 Sometimes thicker than keratinised mucosa
 Epithelium of cheek more than 500 m thick with
broader epithelial ridges
 Stratae:
 Stratum basale
 Stratum intermedium
 Stratum superficiale/ distendum

27.  An important property of any epithelial cell is its
ability to function as a barrier.
 This is brought about by tonofilaments, desmosomes
and hemidesmosomes.
 Ceramides, cholesterol and long chain fatty acids also
regulate the membrane permeability
 Characteristic structures for epithelial cells include:
 Filamentous strands called tonofilaments
 Intercellular bridges or desmosomes

28.  Tonofilaments
 Fibrous proteins synthesized by ribosomes
 Long filaments with diameter of 8nm
 Chemically cytokeratins
 CKs function as components of cytoskeleton and cell contacts.
 All stratified oral epithelia possess CK 5 and 14.
 Keratinised oral epithelium contain Ck 1,6,10,16.
 Non keratinised contains 4,13 and 19.
 May be important in maintaining metabolic homeostasis of cell.
 Recent research on keratins and cell surface markers has focussed
on early identification of aberrant maturation like in case of
cancer.

29.  Anchoring junctions
- adherens junctions (actin filament attachment
sites)
- desmosomes (intermediate filament
attachment sites)
 Occluding junctions
- tight junctions
 Communicating junctions
- gap junctions

30.  Desmosomes or macula adherens are circular or oval areas of
adjacent cell membranes, adhering by intracellular thickenings:
attachment plaques and containing proteins: desmoplakin and
plakoglobin.
 Cadherins penetrate the membrane and enter the intercellular
region of desmosome.
 Hemidesmosomes are present on cells of basal layer and provide
adhesion between epithelium and connective tissue
 Studies indicate that desmosomes and hemidesmosomes differ in
their molecular constituency.
 When these are disturbed like in pemphigus, there is epithelial or
sub epithelial splitting of the epithelial cells

32.  Gap junction or nexus is a region where
membranes of adjacent cells run closely
together; separated by a small gap.
 They allow electrical or chemical
communication between cells.

34.  Tight junction or occluding junction is so
tightly apposed such that intercellular space
is absent.

35.  The major changes involved are
 Change in cell size and shape
 Synthesis of structural proteins and
tonofilaments
 Appearance of new organelles
 Production of additional intracellular
material.

36.  Membrane coating or lamellate granule:
Small membrane bound structures in spinous
cell layer about 250 nm in size and contains
glycolipids formed in Golgi bodies

37. KERATINISED EPITHELIUM NONKERATINISED EPITHELIUM
 Increase in size from basal  Greater increase in cell size
layer to prickle cell layer
 Tonofilaments dispersed and
 Tonofilaments aggregated in less conspicuous
bundles to form tonofibrils
 Lamellate granules appear
 Lamellate granules are circular with amorphous
elongated and contain a content
series of parallel lamellae
 The contents of these have a
 The contents of these different lipid composition
granules are discharged to and forms a less effective
form a lipid rich permeability barrier
barrier

38.  Cells in superficial part of granular layer develop
a noticeable thickening on the inner surface of
cell membrane formed by proteins like
involucrin.
 This contributes to the resistance of keratinised
layer to chemical solvents.
 A similar but less obvious thickening is seen in
surface cells of non keratinised epithelia.

39. Keratohyalin granules of the granular cell layer are characteristic in
keratinised epithelium.
 They have mainly the protein filaggrin and a sulphur rich
compound loricrin thought to facilitate aggregation and formation
of cross-links between cytokeratin filaments of keratin layer.
 As they reach the junction with keratinised layer, the organelles
disappear, the cells dehydrate, flatten, form hexagonal disks
called squames and get packed with filaments cross linked by
disulfide bonds.
 Squames are lost by a process of desquamation and replaced by
cells from underlying layers.

40.  The keratinised layer in oral cavity is composed of up
to 20 layers of squames.
 The tightly packed cytokeratins within an insoluble
tough envelope makes the layer resistant to
mechanical and chemical damage.
 The surface layer of nonkeratinised epithelium
consists of cells with loosely arranged filaments that
are not dehydrated.
 Thus they form a surface that is flexible and tolerant
of compression and distension.

41. Suprabasilar cell with active nuclei
Subsurface epithelial cell with
tight junctions and gap junctions

42.  Histologic sections of oral epithelium show cells with dark
nuclei surrounded by a light halo: Clear cells
 Make up 10% of cell population
 Include melanocytes, Langerhans cells, Merkel cells and
inflammatory cells
 All except Merkel cells lack desmosomal attachments
 They have lesser number of tonofilaments and
desmosomes
 None undergo epithelial maturation

43.  2 types of pigmentation: endogenous and exogenous
 The main endogenous pigments involved with oral pigmentation are
melanin and haemoglobin
 Melanin is produced by melanocytes found in basal cell layer of oral
epithelium and epidermis
 Formed from neural crest ectoderm; found in epithelium at 11th week of
gestation
 They divide and maintain themselves as a separate population.
 Melanin secreted in the form of melanosomes
 Macrophages that have taken up melanosomes appear dark and are
called melanophages
 Pigmentation seen in gingiva, buccal mucosa, hard palate, tongue

44. THE BASAL LAYER OF THE
GINGIVA CONTAINS
MELANOCYTES—
PIGMENT CONTAINING CELLS
WHICH GIVE A BROWNISH HUE TO
PORTIONS OF THE GINGIVA.
THERE ARE ALSO A FEW CELLS IN
THE CONNECTIVE TISSUE WHICH
HAVE TAKEN UP MELANIN
GRANULES -- MELANOPHORES.

45.  Dendritic cell seen above basal layer
 Contains small rod or flask shaped granule: Birbeck
granule
 Revealed under EM with ATP stain
 They form in bone marrow and appear at 11th month IU
 Immunologic function recognising and processing
antigenic material and presenting it to T lymphocytes
 They can migrate from epithelium to regional lymph
nodes

46. THESE CELLS HAVE
DENDRITIC EXTENSIONS
AND ARE IN THE SUPRA
BASILAR LAYER.
THEY FUNCTION AS
ANTIGEN PROCESSING
CELLS AND ARE
MODIFIED
MACROPHAGES.

47.  Situated in basal layer
 NOT Dendritic; contain keratin tonofilaments and
desmosomes
 Said to arise from division of an epithelial cell
 Has small membrane bound vesicles in cytoplasm,
sometimes situated adjacent to a nerve fibre
 These granules release a transmitter across the synapse
like gap between it and the nerve fibre triggering impulse
 Sensory and respond to touch

48. ELECTRON MICROGRAPH OF A
MERKEL CELL FOUND IN THE
DEEP LAYERS OF
EPITHELIUM.
THEY FUNCTION AS
TACTILE PROPRIOCEPTIVE
CELLS AND ARE CONNECTED
TO NERVE FIBERS.

49.  These include lymphocytes most commonly;
PMNLs and mast cells also seen
 Usually seen associated with Langerhans cells
 A few inflammatory cells can be considered a
normal component of the oral mucosa

50. Keratinocytes
produce
cytokines
MSH acts on
melanocytes -
> CKs
pigmentation modulate
function of
Inter relation of Langerhans
cells
keratinocytes and
nonkeratinocytes
IL-1 activates T
lymphocytes Langerhans
and increases cells produce
no of receptors CKs such as IL-
to MSH 1

51.  The junction of epithelium and lamina propria is an
undulating interface at which the papilla of the connective
tissue interdigitates with the epithelial ridges.
 This arrangement increases the surface area of the
attachment enabling applied forces to be dissipated over a
greater area.
 Masticatory mucosa has a greater no. while lining mucosa
has lesser and shorter undulations
 This junction is also important for metabolic exchange as the
epithelium has no blood vessels

52.  In histological sections, (BM) basement membrane between epithelium
and connective tissue appears as a structure less band and stains with
PAS stain.

53.  Lamina lucida:
 Bullous pemphigoid antigen
 Laminin
 Lamina densa (45 nm thick)
 Type IV collagen in chicken wire configuration
 Anchoring fibrils (50 nm thick)
 Type VII collagen
 Collagen of connective tissue:
 Type I
 Type III

55.  Hemidesmosomes represent condensations of bullous
pemphigoid antigen and intermediate filament associated protein
 Cytokeratin filaments loop into the hemidesmosomes
 Proteins of integrin family traverse the membrane and enter the
lamina lucida
 Inserted into lamina densa are small loops of finely banded fibrils
called anchoring fibrils

56.  The connective tissue supporting the oral epithelium
 Divided for descriptive purpose into
 Superficial papillary layer:
 Collagen fibres thin and loosely arranged
 Several capillary loops present
 Deeper reticular (meaning netlike) layer:
 Collagen fibres arranged in thick bundles
 Parallel to surface
 Lamina propria consists of cells, vessels, neural elements
and fibres embedded in amorphous ground substance.

57.  Fibroblasts:
 Principal cell
 Responsible for maintaining tissue integrity by
regulating cell turnover
 LM: cigar shaped(fusiform) or star shaped(stellate)
with long processes that lie parallel to collagen fibres
 Nuclei contain 1 or more prominent nucleoli
 EM: Numerous mitochondria, extensive granular
ER, prominent golgi complex and numerous
membrane bound vesicles
 Low proliferation except in wound healing
 Participates in wound contraction
 In certain cases like gingival overgrowth, secrete more
ground substance than normal

58.  Macrophages
 Histiocyte
 LM: stellate or fusiform cell
 EM: Smaller and denser nuclei; less granular ER, cytoplasm
contains lysosomes
 Ingests damaged tissue or foreign material in phagocytic
vacuoles
 Processing of ingested material may be important in
increasing antigenicity before it is presented to lymphocytes
 2 types: melanophage and siderophage –resultant brownish
colour appears clinically as a bruise

59.  Mast cells
 Large spherical/elliptical mononuclear cell
 Contains large number of intensely staining
granules that occupy its cytoplasm. Stain with
basic dyes due to presence of heparin and
histamine
 Found in association with small blood vessels
 Said to maintain normal tissue stability and
vascular homeostasis

60.  Inflammatory cells:
 Present in CT in the event of an injury or as part of a
disease process
 When in significant numbers, they influence the
behaviour of overlying epithelium by releasing
cytokines
 Acute conditions: PMNLs
 Chronic conditions: lymphocytes, plasma cells
monocots and macrophages

61.  Collagen:
 Type I and Type III in lamina propria
 Type IV and VII in basal lamina
 Type V in inflamed tissue
 Elastic fibres:
 Elastin is responsible for elastic properties of fibre
 Second is a glycoprotein with microfibrillar
morphology
 Initially elastic fibres consist entirely of microfibrils till
they mature and get replaced by elastin

62.  Consists of heterogenous protein-carbohydrate
complexes permeated by tissue fluid
 Chemically proteoglycans and glycoproteins
 Proteoglycans: Polypeptide core with attached GAGs-
hyaluronan, heparan sulphate, versican, decorin, biglycan
and syndecan
 Interaction of these with cell surface molecules (integrins)
important in modulating behaviour and function of cell
 Glycoproteins: Branched polypeptide chain to which few
simple hexoses are attached.

63.  Blood supply of oral mucosa is rich and much
more profuse than skin.
 Blood supply greatest in gingiva
 Human oral mucosa lacks arteriovenous
shunts but has rich anastomoses of arterioles
and capillaries contributing to its ability to
heal more rapidly than skin after an injury.

64. Oral region Sub-terminal branches
Upper lip Superior labial artery
Upper gingiva: Anterior Anterior superior alveolar artery,
Lingual Major palatine artery
Buccal Buccal artery
Posterior Posterior superior alveolar artery
Hard palate Major palatine artery, Nasopalatine artery
Sphenopalatine artery
Soft palate Minor palatine artery
Cheek Buccal artery, Tl branches of facial artery
Posterior alveolar artery, Infraorbital artery
Lower lip Inferior labial artery, Mental artery, Br of inferior alveolar
artery
Lower gingiva: Ant buccal Mental artery
Ant lingual Incisive artery, Sublingual artery
Post lingual Inferior alveolar artery, Sublingual artery
Post buccal Inferior alveolar artery, Buccal artery
Floor of mouth Sublingual artery, Br of lingual artery
Tongue: Ant two thirds Deep lingual artery
Posterior third Dorsal lingual artery

65.  Because mouth is the gateway to the respiratory and alimentary
tracts, it is richly innervated
 The supply is overwhelmingly sensory
 Efferent supply is autonomic, supplies blood vessels and minor
salivary glands and may modulate activity of sensory receptors:
2nd ,3rd divisions of trigeminal nerve
 Afferent supply is from facial, glossopharyngeal and vagus nerves
 The sensory nerves lose their myelin sheaths and form a network
in reticular layer of lamina propria
 Sensory nerves terminate in free and organised nerve endings
 These specialised nerve endings have been grouped according to
morphology as Meissners/Ruffinis corpuscles, Krausses bulbs and
mucocutaneous end organs

66. Sensory nerve networks more developed in oral mucosa
lining anterior than in posterior regions of mouth
 ‘Touch’ more acute in tip of tongue and hard palate
 Touch receptors in soft palate and pharynx help
initiate reflexes like swallowing, gagging and retching
 Temperature reception more acute in vermillion
border, tip of tongue and ant hard palate.

68.  Lip has skin on outer surface and labial
mucosa on inner surface
 Between these tissues lie
vermillion/red/transition zone
 Lips have striated muscle that are part of
muscles of facial expression
 Minor mucous salivary glands in
submucosa beneath oral mucosa
 Skin on outer surface is similar to skin
elsewhere with a keratinised layer of
epithelium on a bed of connective tissue

69.  Lacks appendages of skin
 Occasional sebaceous
glands at corner of mouth
 Requires constant
moistening to prevent
drying
 Epithelium: keratinised but
thin and translucent
 CT papillae of lamina
propria long, narrow; has
capillary loops
 Hence the red colour

70.  Inner surface of lip
 Covered by relatively thick non
keratinised epithelium
 Wide lamina propria
 Short irregular papillae
 Submucosa with minor salivary
glands
 Dense CT strands bind mucosa to
underlying orbicular is ores
 Sebaceous glands may be present in
cheek as Fordyce's spots

71.  Covers areas like hard palate and gingiva
which are exposed to compressive and shear
forces and to abrasion during mastication of
food.
 Epithelium: moderately thick, frequently
orthokeratinised though areas of
parakeratinisation may be seen
 Junction between epithelium and lamina
propria: convoluted with numerous
elongated papillae
 Lamina propria: thick, contains dense
network of collagen fibres as large closely
packed bundles enabling mucosa to resist
heavy loading

72.  Covers immobile structures like palate and
alveolar processes by direct firm attachment
to periosteum to form mucoperiosteum OR
indirectly by a fibrous mucosa
 Lat regions of palate show fat and glandular
tissue interspersed with fibrous mucosa to
cushion mucosa and protect vessels and
nerves

73.  Part of the oral mucosa that covers
Alveolar process of the jaws and
surrounds the neck of the teeth.
 Divided anatomically into:
 Marginal gingiva: Terminal edge or
border of gingiva surrounding teeth
in collar like fashion
 Attached gingiva: Continuous with
marginal gingiva. Width of attached
gingiva is distance between
mucogingival junction and the
projection of gingival sulcus or
periodontal pocket

74.  Width of attached gingiva greatest in incisor
region: 3.5-4.5 mm in maxilla
3.3-4.9 mm in mandible
Least in premolar region:
1.9 mm in maxilla
1.8 mm in mandible
 Width is least in children and increases with
age

75.  Gingival sulcus: Shallow v shaped crevice or
space coronal to attachment of junctional
epithelium
 Normally 0.5 – 3 mm with avg of 1.8 mm
 Depth> 5 mm is called periodontal pocket
 When the tooth first becomes functional, it lies
at the cervical half of crown.
 It contains sulcular fluid, desquamated
cells, neutrophils

76.  Interdental gingiva: occupies gingival
embrasure
 It can be:
Pyramidal
Col- Valley like depression that connects
facial and lingual papilla

77.  Oral epithelium: It covers the
crest and outer surface of
marginal gingiva and surface
of attached gingiva.
 Sulcular epithelium: It lines the
gingival sulcus. It is thin, non
keratinised SSE without
retepegs and extends from
coronal limit of junctional
epithelium to crest of gingiva.

78.  Junctional epithelium:
It consists of collar like
band of non
keratinised SSE. It is
attached to tooth
surface with basement
membrane.

79. • After enamel formation is complete, enamel is covered with
reduced enamel epithelium attached to tooth by
hemidesmosomes and basal lamina.
• During eruption, tip of tooth approaches oral mucosa
causing REE and oral epithelium to meet and fuse.
• Once tip of crown has emerged, REE is termed junctional
epithelium.
• As the tooth erupts, REE grows shorter; a shallow groove
develops between the gingiva and tooth surface to form the
sulcus.

80. The attachment of
junctional epithelium
to tooth is reinforced
by gingival fibres
which brace the
gingiva against the
tooth surface. Hence
called dentogingival
unit
A. Dentogingival
fibres
B. Longitudinal fibres
C. Circular fibres
D. Alveologingival
fibres
E. Dentoperiosteal
fibres

81.  F. Transseptal fibres
 G. Semicircular fibres
 H. Transgingival fibres
 I. Interdental fibres
 J. Vertical fibres

82. 1. Supraperiosteal arterioles along facial and
lingual surfaces of alveolar bone
2. Vessels of periodontal ligament extending into
gingiva and anastomosing with capillaries in
sulcus
3. Arterioles which emerge from crest of
interdental septa to anastomose with vessels of
PDL, capillaries in gingival crevicular area and
vessels that run over alveolar crest

83.  Terminal branches of periodontal nerve fibres
 Br of infraorbital or palatine, or lingual mental
and buccal nerves

84. • Hard palate
It shows various zones:
• Gingival region adjacent to
tooth
• Palatine raphe extending
from incisal papillae
posteriorly
• Anterolaeral area or fatty
zone
• Posterolateral area or
glandular zone between
raphe and gingiva

85.  Underside of tongue, inside of lips, cheeks, floor of
mouth, alveolar processes far as gingiva and soft
palate
 Epithelium: thicker than masticatory mucosa (>500
µm) , nonkeratinised
 Surface flexible, can withstand stretching
 Interface with CT: Smooth with slender CT papillae
 Lamina propria: thicker, fewer collagen fibres which
follow irregular course between anchoring points

86.  Assoc with elastic fibres to control extensibility of
mucosa
 Where lining mucosa covers muscle, it is attached by a
mixture of collagen and elastic fibres
 As mucosa slacks with movement, the elastic fibres
retract mucosa and prevents injury by biting
 Submucosa: thick and loosely attached in alveolar
mucosa and floor of mouth: underside of tongue-
firmly attached

87.  Clinical considerations:
 Lining mucosa is soft and pliable; Gingiva and hard palate
covered by firm immobile layer.
 Local injections: fluid introduced easily into loose lining
mucosa; injection into masticatory mucosa is difficult and
painful.
 Biopsy/wounds: Lining mucosa gapes and requires
suturing; masticatory mucosa does not.
 Inflammation: Accumulation of fluid obvious and painful in
masticatory mucosa; in lining mucosa, the fluid disperses
and inflammation not that evident or painful.

88.  Mucosa of dorsal
surface of tongue
covered functionally by
masticatory mucosa
 It has, in
addition, different types
of lingual papillae which
possess a mechanical or
sensory function

89.  Cover the entire anterior part
of tongue
 Cone shaped structures with a
core of CT covered by a thick
keratinised epithelium
 Form a tough abrasive surface
to help in compressing and
breaking food when tongue is
apposed to hard palate
 Build-up of keratin results
elongation of papillae in some
patients: Hairy tongue
LP- lamina propria
SM- submucosa
Mf - myofibrils

90.  Single fungiform papillae
scattered between numerous
filiform papillae at tip of
tongue
 Smooth round structures
 Appear red high vascular CT
core visible through a thin
nonkeratinised covering
epithelium
 Taste buds present in
epithelium on superior surface

91.  Leaf like papillae
 Seen on lateral margins of
posterior part of tongue
 More frequently in mammals
other than humans
 Pink papillae
 4-11 parallel ridges that
alternate with deep grooves in
mucosa
 Taste buds in epithelium of
lateral walls of ridges

92.  Adjacent and anterior to sulcus
terminalis
 8-12 in number
 Large structures surrounded by
deep circular groove
 Ducts of von Ebner glands open
into these grooves
 Have a CT core covered superiorly
by keratinised epithelium
 Epithelium of lateral walls is non
keratinised, contains taste buds

93.  Barrel shaped structure composed
of 30-80 spindle shaped cells
 Cells separated from underlying CT
by basement membrane
 Apically , terminates just below the
epithelial surface in a taste pit that
communicates with surface through
a taste pore
 3 types of cells:
 Type I- light, most common
 Type II- dark, contain vesicles, adj to
intra epithelial nerves
 Type III-intermediate

94.  Replaced continually
 Presence depends upon presence of a functional
gustatory nerve
 Taste bud cells and merkel cells are the only truly
specialised cells in oral mucosa
 Regions: Sweet at tip, salty and sour on lateral
aspects, bitter and sour at posterior region

95. Generation of taste stimuli
Adsorption of molecules onto membrane receptors on surface of taste bud cells
Activation of signalling cascade: release of TRANSDUCIN, GUSTDUCIN
Change in membrane polarisation
Release of transmitter substance
Stimulation of unmyelinated nerve fibres of glossopharyngeal nerve

96. Smelly fruit
The durian fruit smells
horrible. Some people cannot
bear to eat it because it smells
so foul. But it is called the
"King of Fruits" and tastes
delicious. It is very large (can
be the size of a football) and
comes from South East Asia

97.  Mucocutaneous junction
 Mucogingival junction
 Dentogingival junction

98.  The skin with hair follicles and sebaceous and sweat
glands is continuous with the oral mucosa at the lips
 Epithelium keratinised, with thin long CT papillae
containing capillary loops
 This brings blood close to the surface and gives strong
red coloration called red /vermillion zone
 The line separating vermillion zone from skin of lip
called vermillion border. In young persons, this border
demarcated sharply, later becomes diffuse

99.  Vermillion zone lacks salivary glands, contains
only a few sebaceous glands, it tends to dry out,
becomes cracked and sore in cold weather
 Between vermillion zone and thicker non
keratinised labial mucosa is an intermediate
zone covered by parakeratinised epithelium
 In infants this region is thickened and more
opalescent: suckling pad

100.  Although masticatory mucosa meets
lining mucosa at more than 1 site, most
abrupt is between attached gingiva
and alveolar mucosa
 Identified clinically by indentation
called mucogingival groove and by
change from bright pink of alveolar
mucosa to paler pink of gingiva
 Epithelium of attached gingiva is
keratinised or parakeratinised
 Lamina propria contains numerous
coarse collagen bundles attaching
tissue to periosteum; reflected
clinically as stippling

101.  The structure of mucosa changes at mucogingival
junction where alveolar mucosa has thicker
nonkeratinised epithelium over loose lamina propria
with numerous elastic fibres extending into thick
submucosa

102.  Region where oral mucosa meets surface of
tooth
 Important because it represents a potential
weakness in the otherwise continuous
epithelial lining
 Principal seal between epithelium and
enamel
 In germ free animals and in strictly healthy
plaque free gingivae, sulcus is absent and
gingival margin corresponds to coronal
extent of junctional epithelium
 In avg human mouth, gingival sulcus has a
depth of 0.5-3 m with an avg of 1.8 mm

103.  The basic considerations in oral mucosa are variation
in tissue colour, dryness, smoothness or firmness and
bleeding tendency of gingiva
 Periodontal pocket: It is a pathologically deepened
gingival sulcus as a response to plaque toxins and
subsequent immunologic response.
 Restorative dentistry: In young patients, when the
clinical crown is smaller than the anatomic crown, it is
difficult to prepare a tooth for an abutment or crown.
The restoration may require replacement when the
crown is fully exposed

104.  Gingival recession: May result in cemental /root caries
and sensitivity of the exposed dentin
 Keratinisation of gingiva: Can be achieved by massage
or brushing thus helping in stimulation and
minimising plaque accumulation
 Discoloration of gingiva: Metal poisoning by lead or
bismuth causes characteristic discoloration. Blood
dyscrasias can be diagnosed by characteristic
infiltration of the oral mucosa. Viral diseases like
measles manifest as typical lesions of oral mucosa

105.  Changes of tongue: In scarlet fever, atrophy of lingual
mucosa causes peculiar redness of Strawberry tongue.
Systemic diseases such as vitamin deficiencies lead to
typical changes as Magenta tongue and beefy red
tongue.
 Macule: A flat spot/stain/discoloration of the oral
mucosa. Amalgam tattoo, nevus, rash of secondary
syphilis
 Papule: Small rounded pimple like variably coloured.
White variably patterned elevations of Lichen planus

106.  Plaque: Slightly raised clearly demarcated area
that may be smooth pebbly cracked or fissured.
Leukoplakia, Erythroplakia
 Vesicle: Small circumscribed elevated blister not
more than 5 mm in diameter with covering layer
of epithelial cells and containing an
accumulation of fluid. Herpes labialis
 Pustule: Vesicle predominantly containing pus

107.  Bulla: Large vesicle or blister. Pemphigus and drug
rections. May appear white due to necrosis of
epithelium forming pseudomembrane
 Ulcer: Sore characterised by loss of epithelium
yielding a punched out area. Traumatic
ulcers, aphthous stomatitis, cancer and tuberculosis
 Fissure: Narrow linear crack of epidermis with an ulcer
at its base. Fissured tongue
 Erosion: Partial loss of upper layers of epithelium.
Toothbrush trauma, erosive lichen planus

108.  Cyst: Cavity lined by epithelium containing fluid or cells.
Gingival cyst
 Nodule: Localised elevated mass of tissue projecting from
surface. Fibroma, mucocele
 Tumour: swelling of part of an organ. Inflammatory,
Developmental or neoplastic. Carcinoma is a malignant
tumour of epithelial cells
 Wheal: Pruritic reddened oedematous papule. Allergy
 Sinus/sinus tract: leading from underlying cavity cyst or
abscess and opening onto surface

109.  Scar: White depressed mark, line or area
representing healing after injury.
Gingivectomy, apicoectomy, deep
inflammation, previous trauma

111. • In pathological conditions, the cytokeratin
profile of epithelium has been seen to be
altered.
• Pancytokeratin antibodies are now in use to
differentiate neoplasms.
• Also helpful in determining the origin of cysts
within jaws and to differentiate odontogenic
cysts from non odontogenic cysts. (CK 13)

112. • Ten Cate’s Oral Histology: Development, Structure and function by
Antonio Nanci. 6th edition
• Oral Anatomy Histology and Embryologyby Berkovitz, Holland, Moxham
. 3rd edition
• Essentials of Oral Histology and Embryology by James K. Avery
• Carranza;s Clinical Periodontology by Newman, Takei, Carranza. 9th
edition
• Dentistry for Child and Adolescent by Mc Donald, Avery, Dean . 8th
edition
• Orban’s Oral Histology and Embryology . 10th edition