Seminar on oral mucosa in health

1. ORAL MUCOSA IN
HEALTH
BY
FATHIMA E.M
MDS 1st year
SEMINAR NO. 1

2. Contents
• Introduction
• Functions of oral mucosa
• Difference b/w skin & mucosa
• Development of oral mucosa
• General consideration
• Classification
• Histological structure of epithelium
• Keratinized and non-keratinized regions
• Immunology of oral mucosa
• Wound healing in oral mucosa
• Age changes in oral mucosa
• Clinical considerations
• Lesions of oral mucosa
• Conclusion
• Reference

3. Introduction
• The surface of the oral cavity is lined by mucous
membrane.
• Extent- from skin of the lip through the vermilion
border to mucosa of pharynx.
• Areas involved in mastication have different
structure than the floor of the mouth or the mucosa
of the cheek

4. Functions of oral mucosa
1. Defensive
2. Lubrication
3. Sensory
4. Protection
5. Aesthetics
Defensive
a. Prevents entry of microorganism
b. Mucosa is impermeable to bacterial toxins
c. Secretes antibodies
Lubrication
a. Secretion of salivary glands keeps oral mucosa moist
b. Moist oral cavity helps - speech, mastication, swallowing, perception of taste

5. Sensory
Sensitive- touch, pressure, pain, temperature
Protection
a. The oral mucosa protects the deeper tissues from
mechanical forces (mastication and abrasive kind of food)
Aesthetics
a. Skin color, texture & appearance in esthetics
b. Vermilion border of lip – in females

6. Difference b/w skin and mucosa
Skin Oral mucosa
a) Epithelium and connective tissue a) Epithelium and connective tissue
b)Epithelium always – ortho keratinized b) Epithelium depending upon location –
keratinized (ortho or para) & non keratinized
c) Contains – stratum lucidum c) Lack of stratum lucidum
d) Skin appendages – hair follicles, sebaceous
glands & sweat glands present
d) Skin appendages are absent
Few sebaceous glands are present
e) Salivary glands - absent e) Salivary glands - present
f) Slower healing and scar formation f) Rapid restoration

8. Development of oral mucosa
• Epithelium – derived from ectoderm & endoderm
• Anterior part - derived from the ectoderm.
• Structures from the branchial arches like tongue , epiglottis & pharynx
covered by epithelium derived from the endoderm
• 5- 6 weeks single layer of cells have formed lining oral cavity
• 7 weeks- circumvallate & foliate papillae later fungiform
• 10 weeks – filiform papillae appear
• 10-14 weeks – cellular degeneration forming oral vestibule

9. • 8-11 weeks
a) palatal shelves elevates & close
b) capillary buds & collagen fibers detected
c) morphology of future mouth is apparent
• 13-20 weeks
a) Keratinized and non keratinized mucosa becomes apparent
b) Keratohyalin granules & cytokeratins appear
c) Epithelium remains parakeratinized in masticatory mucosa,
orthokeratinization is seen only after teeth erupt.
d) Langerhans cells & melanocytes appear

10. • In the lamina propria
a) 6-8 weeks - reticular fibers appear
b) 8-12 weeks - collagen fibers appear
c) 17- 20 weeks - elastic fibers appear

11. General consideration
• Oral mucosa consist of
epithelium
connective tissue
submucosa
1.Epithelium
a. It can be keratinized or non keratinized
DERMIS
ortho para
• Epithelium and conn.tissue is folded into corrugation
Epithelium project to conn.tissue – rete ridges
Papillae of conn.tissue project towards
epithelium carrying blood vessels and nerves

12. Epithelium
Connective tissue
• Rete ridges helps in
a. Better adhesion
b. ses surface area b w conn.tissue and epithelium
c. Transport of nutrients and other material
d. To disperse the forces
• Masticatory mucosa have long rete ridges than lining mucosa
• More rete ridges - strength of epithelium & conn.tissue
2. Lamina propria
• Divided into
• Include cells – fibroblast , defence cells, extracellular components (i.e.; collagen fibres, elastic fibres and ground
substance )
Basement membrane of 1-2 micrometre
Papillary portion
I. Loose conn.tissue
II. Many capillary loops & nerves
Reticular portion
I. Less cellular & denser
II. Parallel arrangement to epithelium

13. • Reticular portion - present always
• Papillary portion - can vary depending on the presence & absence of rete ridges
3. Submucosa
• Is the deeper conn.tissue
• Contains – large blood vessels & nerves, minor salivary glands, fat cells etc.
• Divided into compartments with vertically arranged collagen fibres
• Vertically arranged collagen and elastic fibres
attach mucosa to underlying structure
prevent mucosal folding
• Submucosa absent – in gingiva & some regions of hard palate – in those region lamina propria directly
attached to periosteum of bone – i.e.; known as mucoperiosteal attachment (makes mucosa –tightly
bound to the bone& immovable)

14. Classification
BASED ON FUNCTION
• Masticatory mucosa - gingiva and hard palate
• Lining or reflecting mucosa - lip, cheek, vestibular fornix, alveolar
mucosa, floor of mouth and soft palate
• Specialized mucosa - dorsum of the tongue and taste buds
BASED ON TYPE OF EPITHELIUM
• Keratinized
• Non keratinized

15. • Masticatory mucosa:
a) Bound to bone i.e.; mucoperiosteal attachment
b) Bears stress
• Lining mucosa:
a) Covers musculature
b) Helps in contraction and relaxation of cheeks, lips, tongue and muscles of
mastication aid in movement of mandible
• Specialised mucosa:
a) Bears taste buds
b) Have a sensory function

16. Histological structure of epithelium
KERATINIZED EPITHELIUM NON KERATINIZED EPITHELIUM
1. Stratum basale
a. Cuboidal or columnar cells - basement
membrane
b. Named as stratum germinativum -
undergo mitotic division
c. Basophilic cytoplasm
d. Centrally placed nucleus
(hyperchromatic)
e. Nucleus arranged perpendicular to
basement membrane
f. Nucleus is larger in size
2. Stratum spinosum (prickle cell layer)
a. Several polyhedral cells
b. Basophilic nature ses
c. Cells are larger
d. Centrally placed nucleus
e. Prickly or spiny appearance
f. As the cells mature moves
superficially in size
with flattened nucleus
1.Stratum basale
a. Cuboidal or columnar cells
b. Centrally placed nucleus
(hyperchromatic)
c. Nucleus occupies 13rd of cells
d. Basophilic cytoplasm
( bcoz of high RNA content)
2.Stratum intermedium
a. Polyhedral cells
b. Eosinophilic cytoplasm
c. Cells are larger in size
d. Centrally placed nucleus
e. Prickly appearance not distinct- cells
are closer
f. As the cells mature --- moves
superficially ------- increase in size
with flattened nucleus

17. KERATINIZED EPITHELIUM NON KERATINIZED EPITHELIUM
3. Stratum granulosum (granular cell layer)
a. Flattened cells
b. Cytoplasm filled with basophilic
granules – keratohyaline granules –
stratum granulosum
c. Nucleus flattened
4. Stratum corneum (cornified layer)
a. Superficial layer
b. Contains keratin squames – larger &
flatter
c. Eosinophilic
d. Cells reach cornified layer
nucleus undergo degeneration
e. In orthokeratinisation – nucleus absent
and in parakeratinisation – pyknotic
nucleus retained
f. Parakeratinized epithelium – mainly
seen gingiva with less prominent
keratohylaine granules
3.Stratum superficiale
a. Few layers of flattened cells
b. Nucleus flattened with long axis
parallel to outer surface
c. These cells undergo desquamation
d. Cytoplasmic organelles - indicates
in protein synthesis

19. Ultrastructure
• Keratohyaline granules
i. Source of protein
ii. Electron dense bodies devoid of internal structure
iii. First present in spinous layer & become prominent in granular zone
iv. Disappear as they enter cornified layer
v. Contain- cysteine rich protein (disulphide bonds contribute to
chemical inertness & strength of cornified layer)
• Lamellar granules
i. Or Odland bodies
ii. Size – 300nm in diameter
iii. Contain- free sterols, polar lipids , hydrolytic enzymes
iv. Seen at the of spinous zone, near Golgi apparatus of keratinocytes & migrate into
cytoplasm , fuses with plasma membrane
v. Contents are discharged into intercellular spaces
vi. Once contents are discharged – organised to lamellae – provide structural base
for epidermal permeability
• Tonofilament
i. A cytoplasmic protein- with protein, keratin and are found in all epithelial cells

20. Non keratinocytes
1. Melanocyte
2. Langerhan’s cells
3. Merkel cells
4. Inflammatory cells
1. Melanocytes
i. Melanin producing cell
ii. Melanosomes are the cells
iii. Melanin production depends on melanosome stimulating hormone
iv. Pigmentation in diff individual –depend on the activity of melanocytes
v. Helps – import colour to skin and mucosa and protect u-v light

21. 2. Langerhan’s cells
i. Immuno-competent cells (trap antigens entering mucosa , process it &
present it to the immune system). So named Antigen presenting cell
(They produce cytokines (IL-1) & activate T lymphocytes )
ii. Racquet or flask shaped cytoplasmic organelle called Birbeck granules
3. Merkel cells
i. Contain neurosecretory granules
ii. Presence of granules- suggest sensory function of merkel cells
4.Inflammatory cells
i. Mainly seen are lymphocytes and neutrophils
ii. Lymphocytes – perform defensive function

22. Intercellular junctions
1. Desmosomes 2. Tight junction
3. Gap junction 4. Hemidesmosomes

23. Keratinized and non keratinized mucosal regions

24. Gingiva
• Gingiva covers alveolar process & surrounds neck of tooth
• Extent – dento-gingival junction to alveolar mucosa
• Macroscopically – marginal gingiva (free gingiva), interdental papilla, attached gingiva
• Marginal gingiva
i. Scalloped
ii. It is separated from attached gingiva by free gingival groove

25. • Gingival sulcus
i. is v shaped
ii. Depth varies 0.5 – 3mm
iii. Greater than 3mm – gingival or
periodontal pocket
• Interdental papilla
i. Gingiva filling interdental space
ii. In 3D view:
anteriorly-pyramidal in shape
posteriorly- tent shape with high
points & valley below contact
area. Valley- col –lined by non
keratinized epithelium
Col- weak area – prone to
periodontal disease
• Attached gingiva
i. Firm , resilient and immobile
ii. Tightly bound to bone
iii. irregular with elevation &
depression – stippling

26. Microscopic structure of gingiva
• consist of epithelium and conn.tissue
• Epithelium – Oral epithelium
Sulcular epithelium
Junctional epithelium
• Conn. Tissue
Contain dense collagenous tissue- arranged as bundle of fibres- known as gingival fibres
1. Dentogingival
2. Alveologingival
3. Circular
4. Dentoperiosteal
5. Transseptal fibers

27. Blood supply of gingiva
1 . Supra periosteal arterioles
a) gingival sulcus
b) free gingiva
2. Vessels of PDL
a) col
3. Arterioles from crest of interdental septa
a) attached gingiva

28. Palate
• Forms roof of oral cavity
• Divided into a)immovable - hard palate (anteriorly)- hard bony support
b) movable - soft plate (posteriorly) - fibrous tissue
• Macroscopically divided into
1. Gingival region- adjacent to the teeth
2. Palatine raphe- median area, extending from incisive or palatine papilla posteriorly
3. Anterolateral area or fatty zone – b/w raphe & gingiva
4. Posterolateral area or glandular zone – b/w raphe & gingiva

29. Microscopically
• Keratinized mucosa
• Long & interdigitating rete ridges – helps to bear masticatory force
• Lamina propria- thicker in anterior than posterior
• Rugae- conn. tissue dense with interwoven collagen fibers
• Incisive papilla – contain remnants of nasopalatine ducts lined by pseudo
stratified squamous epithelium
• Anterior part – filled with adipose tissue – fatty zone
• Posterior part – filled with mucous glands – glandular zone

30. Tongue
• Muscular organ
• Role- speech, mastication, deglutition, taste sensation
• Features
i. “V” shaped sulcus divide dorsum of tongue
Post 1/3rd – pharyngeal part
ii. Foramen caecum – opening of thyroglossal duct
iii. Ventral aspect – non keratinized
bound to underlying musculature
iv. Papillae of tongue
a) Filiform – hair like, numerous, pin point, cone- shaped
makes tongue rough
help - crushing of food
taste buds – absent
non keratinized
Ant 2/3rd - oral part

31. b) fungiform – mainly on the tip & lateral margin
seen as red round projections
non- keratinized
c) circumvallate –seen ant. to sulcus terminalis
10 -12 large papillae
lining epithelium- keratinized & lateral aspect – non keratinized
presence of von Ebner’s minor salivary gland
d) foliate – lateral margins of post. region of ant . 2/3rd tongue
contains series of folds forming cleft

32. Taste buds
• Are specialized sense organs
• Location
- Superficial surface of fungiform papillae
- Lateral walls of circumvallate papillae
- Cleft walls of foliate papillae
- Also seen in – post part of uvula, epiglottis, pharyngeal region etc.
• Barrel shaped with 30- 50 spindle shaped modified epithelial cells
• Extent - from basement membrane to epithelial surface
• At epithelial surface – tapered end of cell end in a small opening called taste pore
through with cells communicate to exterior

33. • Morphologically
- type I cells - dark cells
- type II cells - light cells
- type III cells - intermediate cells
- type IV cells - basal cells

34. Dento-gingival junction
• Junction b/w tooth & gingiva
• Formation
Amelogenesis
Primary
enamel cuticle
Enamel organ
Reduced
enamel
epithelium
During
eruption
REE + oral
epithelium
Degeneration
of cells at tip of
crown
eruption
Nasmyth’s
membrane

37. Shift of dentino enamel junction
• Stage 1 : attachment epithelium completely on enamel
bottom of gingival sulcus – on enamel
• Stage 2 : attachment epithelium partly on enamel & cementum
bottom of sulcus – on enamel
• Stage 3 : attachment epithelium completely on cementum
bottom of sulcus – at CEJ
• Stage 4 : attachment epithelium migrates apically on cementum
bottom of sulcus on cemental surface – exposing root
1st & 2nd stages are physiological while 3rd & 4th stages are pathological

39. Immunology of oral mucosa
Initiate
inflammatory
responses
(depending on
the destruction
& severity)
Microbes,
necrotic
cells &
hypoxia
Result in
clinical and
pathological
manifestations
Activation of
immune cells in
the oral cavity
• There are numerous lymph nodes draining to head & neck
that contribute to immune system of oral cavity
• Major lymphoid organs are tonsils & adenoids – making
waldeyer’s ring

41. • Immune system protects – teeth, jaws, gingiva & oral mucosa against
infection
• Immune system is a part of an extensive & specialised
compartmentalised mucosa associated lymphoid tissue (MALT)
• Host response is differently represented by – oral mucosa, saliva &
salivary glands & gingival crevice

42. Oral mucosa
a) Intact stratified squamous epithelium supported by lamina
propria act as mechanical barrier against microorganism
b) Continuous exfoliation of epithelial cells limits microbial
colonisation
c) Mucosal defence – membrane coating granules
transduction of antibody
barrier presented by basement membrane

43. d) Langerhan’s cell – (antigen presenting cells)
i. Trap antigen entering mucosa , process & present to the
immune system
ii. Prevents entry of harmful pathogens
iii. Maintains homeostasis – by avoiding immune reaction
towards harmless foreign substances or particles from nutrition
e) Epithelial cells - produce cytokines like IL- 1ꞵ, TNF-α & IL-8
f) Cytokines -secreted by macrophages , fibroblasts, dendritic cells,
mast cells & intra epithelial lymphocytes in the oral mucosa

44.  Saliva and salivary glands
• Has mechanical effects – flushing microorganism from mucosa & tooth
surface
• Contains anti microbial agent
• Xerostomia – prone to dental caries & candidiasis
• Contains mucins, histatins , peptides, peroxidase, and growth
factors - role in oral homeostasis.

45.  Gingival crevice
• Neutrophils from gingival capillaries
• Neutrophils – capable of phagocytosis & killing of micro organism
• Quantitative deficiency of neutrophil – neutropenia
causes – uncontrolled extension of dental plaque
loss of periodontal attachment
oral candidiasis
• Qualitative defects – genetic
causes – aggressive forms of periodontitis

46. Wound healing of oral mucosa
• Infections following an injury to the oral cavity can increase the risk
of bacteremia
• In the case of oral mucosal infection, bacteremia can also lead to
systemic inflammation and sepsis
• Systemic infection can lead to endocarditis, joint infections, Behçet's
syndrome, Crohn's disease etc
• Oral infections and poor wound healing leading to systemic infections
which can compromise the body's innate ability to heal.

47. Stages of wound healing
• Hemostasis
• Inflammation
• Proliferation
• Maturation

49. Age changes of oral mucosa
• Elderly person – smoother & dryer surface than youngster
• Histologically epithelium appear thinner
• Smoothening of epithelium – connective tissue interface – flattening of
epithelial ridges
• Dorsum of tongue - in no. of filiform papillae
• ed epithelial proliferation & ed rate of tissue turnover
• ed Langerhan’s cells - cell mediated immunity

50. • Elderly persons – nodular varicose veins under surface of tongue - ( caviar tongue)
• Lamina propria - cellularity & in collagen
• ed no. of sebaceous glands - cheeks & lips
• Atrophy of minor salivary gland with fibrous replacement
• Post menopausal women- presents symptoms like burning sensation, dryness
of mouth & abnormal taste

51. Clinical consideration
1. Clinical conditions resulting in alteration in structure of oral mucosa
Oral cavity is the mirror of general health of a person
a. mucosa becomes reddish – inflammatory condition
b. patchy brownish pigmentation – conditions involving melanocytes
c. mucosa becomes stiff & non – stretchable in OSMF & scleroderma
(due to excessive fibrosis of conn. tissue)

52. d. Dermatological disorders manifest oral mucosal lesion such as fluid
filled vesicles , ulcers, erosions, red patches etc. Ex- oral lichen planus,
pemphigus , pemphigoid etc.
e. Loss of papillae – bald tongue appearance in anemias
f. Use of tobacco- oral mucosal cancer or potentially malignant disorders - present as
white patches or plaques, ulcers, ulcero proliferative growth
Lichen planus Pemphigus Mucous membrane
pemphigoid

53. Bald tongue Leukoplakia
Ulcero proliferative growth

54. 2. Histological changes
a. Hyperkeratosis - in thickness of keratin layer
b. Acanthosis – abnormal thickening of of spinous layer
c. Atrophy – abnormal thinning of epithelium
d. Acantholysis – destruction of desmosomal junctions
causes loss of intercellular adhesion
main feature – pemphigus & viral infections
e. Basilar hyperplasia - cell proliferation in basal cell layer – forms multiple layers
of basal cells

55. f. Basal cell degeneration – destruction of basal cell - feature in lichen planus
g. Loss of stratification – i.e; loss of arrangement of epithelial cells in different layers
feature – epithelial dysplasia
h. Potentially malignant disorders & oral mucosal cancer present with number of
cellular & architectural changes in epithelium – can be a feature of epithelial
dysplasia

56. 3. Structural variation
a. masticatory mucosa
- no submucosa
- mucosa not stretchable & firmly attached to underlying bone
- so injections are painful & cannot be dispersed easily
- wounds do not gape open
- do not require suturing
- wound heals by secondary intention

57. b. lining mucosa
- injection – less painful & disperse easily
- wounds gape open
- requires suturing
- wound heals by primary intention

58. Appearance of lesions by colour
• White
• Red
• White / red
• Blue
• Brown/ black

59. Smoker’s melanosis
Leukoplakia Erythroplakia
Geographic tongue

60. Appearance of lesions by pattern
Surface Base
• Smooth
• Granular
• Verrucous
• Papillomatous
• Papillomatosis/pebbly
• Papillomatosis/cobblestone
• Bosselated
• Lobulated
• Vesicle/ bullae
• Atrophy/erosion/ulcer
• Pedunculated
• Sessile
• Nodular
• Dome - shaped

61. Appearance of lesions by pattern

62. Ulcerated lesion
Atrophy of buccal mucosa Erosion of labial mucosa

63. Lymphangioma- smooth/pebbly Lipoma- dome shaped exophytic lesion

64. Bullous lesion Pedunculated lesion
Pappillomatous lesion Lobulated lesion
Cobblestone pattern
Bosselated pattern

65. Peripheral oral exophytic lesions

66. Conclusion
• Oral mucosa present unique structure and characteristics
• Oral mucous membrane maintains integrity of oral cavity in health &
disease
• Clinician must know its normal variation in the structure and function
• Then only we can identify the abnormality
• Detection of changes in the mucosa would help in early diagnosis &
treatment

67. References
• Orban’s oral histology and embryology textbook
• Oral Mucosa in Health and Disease -A Concise Handbook Lesley Ann Bergmeier
Editor
• Essentials of oral biology – Maji Jose
• Mortazavi H, Safi Y, Baharvand M, Rahmani S, Jafari S. Peripheral exophytic oral
lesions: a clinical decision tree. International Journal of Dentistry. 2017 Jul 5;2017.
• Walker DM. Oral mucosal immunology: an overview. Annals-academy of Medicine
Singapore. 2004 Jul 1;33:27-30.
• Toma AI, Fuller JM, Willett NJ, Goudy SL. Oral wound healing models and emerging
regenerative therapies. Translational Research. 2021 Oct 1;236:17-34.