Oral mucous membrane - Oral mucosa

1. ORAL MUCOUS MEMBRANE 1 Check out ppt download link in description Or Download link : https://userupload.net/3ppacneii1wj

2. CONTENTS  INTRODUCTION  DEFINITION  FUNCTIONS  CLASSIFICATION  COMPONENTS OF ORAL MUCOSA  AGE CHANGES IN ORAL MUCOUS MEMBRANE  CLINICAL CONSIDERATIONS  CONCLUSION

3. INTRODUCTION The skin, oral mucosa and intestinal lining, all consist of two separate tissue components, which are, the covering epithelium and an underlying connective tissue. As these tissues, together perform a common function, the oral mucosa must be considered as an organ. Understanding the complex structure of a tissue or organ often is easier, when it’s function is known. The structure of oral mucosa reflects a variety of functional adaptations. Any change in these functional adaptations, leads to pathology.

4. DEFINITION “The term moist membrane is used to describe moist lining of GIT, nasal passages and other body cavities that communicate with exterior. In the oral cavity this lining is called oral mucous membrane.”

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6. FUNCTIONS Protection : Separates and protects deeper tissues and organs from mechanical stresses/ forces, and external environment. Sensation : Temperature, touch and pain sensation. Tongue has taste buds. Reflexes like swallowing, gagging, salivating, also are initiated by receptors in oral mucosa.

7. 7 • Secretion : Saliva is secreted by salivary glands and contributes to the maintenance of a moist surface. • Thermal regulation : In some animals (dog), considerable body heat is dissipated through oral mucosa by panting. For these animals, oral mucosa plays a major role in regulating of body temperature. This function is not active in humans.

8. 8 Absorption : Certain substances like nitrates are absorbed from sublingual region. Excretion : Excretes metabolites. Aesthetics : Gingiva and lip mucosa enhance facial esthetics.

9. Oral Mucous Membrane Classification 1-Keratenized mucosa ( Masticatory mucosa) (A) Gingiva (B) Hard palate 2- Non-keratenized mucosa (Lining mucosa) (A) Firmly attached (B) Loosely attached I- Soft palate II-lip III-cheek IV-ventral S tongue I- Floor of mouth II-Vestibule III-alveolar mucosa3- Specialized mucosa Dorsal surface of tongue 9

10. HISTOLOGY OF ORAL MUCOSA There are mainly 2 components 1. oral epithelium made up of stratified squamous epithelium 2. underlying connective tissue called lamina propria • the interface between epithelium and connective tissue is usually irregular and upward projections of connective tissue called the connective tissue papillae • these papillae interdigitate with epithelial ridges • the structural interface between epithelium and connective tissue called the basement membrane 10

11. Oral Mucous Membrane Epithelium Lamina Propria Submucosa Periosteum Bone 11

12. THE EPITHELIUM • It is derived from the embryonic ectoderm • The cells vary from cuboidal to flat squamous cells • This epithelium may be keratinized or non keratinized depending upon the functional requirements • Keratinized epithelium may be ortho or para keratinized 12

13. 13 • Epithelial cells are called keratinocytes as they contain within the cells fine filaments called tonofilaments. • These are fibrous proteins synthesized by ribosomes. • When tonofilaments form bundles of filaments they are called tonofibrils. • Tonofilaments are formed in keratinized epithelium only. • Bundles of tonofilaments attach to an intercellular thickening called Attachment Plaque Which in turn adhere to an oval or circular area of adjacent cell membrane called DESMOSOME.

14. 14 • The attachment of epithelial cells to one another is by desmosome. • The attachment of epithelial cell to connective tissue is by Hemi Desmosome. • A basal lamina seperates the epithelium & lamina propria. • It has an upper clear layer called Lamina Lucida in contact with the basal cells of the epithelium & lower dense layer called Lamina Densa which is contact with reticular layer of lamina propria. • The cells of the basal cell layer are connected to the lamina lucida by Hemidesmosomes.

16. EPITHELIAL MATURATION 16 PATTERNS OF MATURATION Keratinization Non-Keratinization

17. 17 Stratum Basale Stratum Spinosum Stratum Granulosum Stratum Corneum. KERATINIZED EPITHELIUM

18. 18

19. Stratum basale : • They are present above the basement membrane. • They have cuboidal or columnar cells. • Cells of the basal layer shows most mitotic activity. • This layer is also called Germinative layer. • They are attached to the basement membrane by hemidesmosomal junction. 19

20. Stratum Spinosum : • Arranged in several rows. • Cells are larger elliptical or spherical in shape • Cells are fused together due to the presence of intercellular bridges or desmosomes. • Cells of spinous layer are joined together by intercellular bridges giving the cells a prickly appearance • They contain glycolipids originating from golgi complex. 20

21. 21 Stratum Granulosum : • Cells of stratum granulosum are flat and are found in layers of three to five cells thick • This layer is prominent in keratinized epithelium (and absent in nonkeratinized epithelium) • These cells have keratohyaline granules in their cytoplasm • Keratohyaline granules help to form the matrix of the keratin fibres found in the superficial layer

22. Stratum Corneum : • Cells are flat, devoid of nuclei and full of keratin filament surrounded by a matrix • These cells are continuously being sloughed and are replaced by epithelial cells that migrate from the underlying layers • The cells are usually dehydrated • In case of orthikeratinized layer there is no retension of nuclei • In parakeratinized layer there is retention of nuclei 22

23. NON KERATINIZED EPITHELIUM 23 Stratum basale Stratum intermedium Stratum superficial / stratum distendum

24. Stratum basale : • This layer is similar to that of keratinized epithelium. • Only difference is that the cells of this layer in non keratinized epithelium are slightly larger than that of keratinized epithelium. • Intercellular bridges are less conspicuous. 24

26. Stratum Intermedium : • Glycogen is present • Rarely keratohyaline granules are also visible at this level, but they are not associated with tonofilaments. Stratum Superficiale : • Cells appear slightly more flattened than other layers. • They contain dispersed tonofilaments and nuclei and dehydrated cells. • This surface is flexible and tolerant to compression and distension. 26

27. KERATINIZED & NON-KERATINIZED MUCOSA Stratum basal Stratum spinosum Stratum intermedium Stratum granulosum Stratum superficial Keratohyaline Gs. Keratenized epithelium Non-keratenized epithelium Stratum cornium 27

28. LAMINA PROPRIA • Found below the epithelium • Has 2 parts and are 1.Papillary 2.Reticular • Papillary portion is projections of connective tissue into the epithelium • Increase in length of papillae is seen in areas where additional mechanical adhesion is required between epithelium and connective tissue • Eg; masticatory mucosa • Reticular portion is present below this layer • This contain mainly collagen fibres blood capillaries 28

29. • SUBMUCOSA----- It is a connective tissue of varible thickness • Serves primarily as attachment for lamina propria to the underlying bone or muscle • Submucosa contains glands adipose tissues vascular and neural components 29

30. KERATINOCYTES Constitute the major part of epithelial cells The cells are arranged in different layers During maturation they either change to keratin or share in keratin formation These cells have the following criteria:-  Always present in sheets & attached to each other by one or more type of cellular junctions  Cytoplasm of these cells is stained with H & E  Cytoplasm contains the tonofilaments 30

31. NON-KERATINOCYTES Present in both keratinized & non-keratinized epithelium & have the following criteria:- • Appear as clear cells by ordinary H&E stain, they need special stains • Present as scattered cells & not in sheets • A clear hallows around their nuclei • Their cytoplasm is free from tonofilaments • No cellular junctions • Do not play any role in synthesis of keratohyaline granules or keratin 31

32. 32 LANGERHANS’ CELLS • Are found in the stratum spinosum &, occasionally in stratum basale. • These cells have long, thin extensions of the cytoplasmic membrane, called dendrites. • They can be distinguished from keratinocytes by the absence of desmosomes & tonofilaments. • Can be distinguished from the melanocytes by the absence of premelanosomes.

33. 33 •Contains the rod shaped or racquet shaped birbeck’s granules, which allows for positive identification at the ultrastructural level. •Are antigen presenting cells. •They engulf antigens from the external environment & the intracellular lysosomes split the antigens into peptide components. These fragments are then transferred to T- lymphocytes.

34. 34 MERKEL CELLS • Are situated in the basal layer of the gingival epithelium. • Possess occasional desmosomes & tonofilaments. • Are usually associated with an axon terminal. • The merkel cell & associated axon terminal form a complex that serves as a touch receptor. • Are usually found in groups or clusters.

35. 35 MELANOCYTES • Are melanin producing cells located in the basal layer of the gingival epithelium. • These cells arise from the neural crest. • Lack tonofibrils, desmosomes & hemidesmosomes. • Are highly dendritic in nature. • The most characteristic feature of the melanocyte is the melanosome granule found within the cytoplasm.

36. 36 • A more heavily pigmented gingiva is due to the production of melanin & its subsequent uptake by the epithelial cells. • There is a great variability in the location & distribution of melanin in the oral cavity.

37. 37 • Present variably. • Contains large circular nucleus • Cytoplasm is scanty with few organelles. • No desmosomes and tonofilaments present. • Associated with inflammatory response in oral mucosa. Lymphocytes(Inflammatory cell) :

38. KERATINIZED MUCOSA (MASTICATORY MUCOSA) During mastication, parts of oral mucosa are subjected to forces & pressure  Gingiva  Hard Palate 38

39. • GINGIVA is a masticatory mucosa and covers the alveolar process of the jaw and surrounds the neck of the teeth. • The gingival extends from the dentogingival junction to the alveolar mucosa. • The stratified squamous epithelium may be keratinized or nonkeratinized but most often it is parakeratinized. 39

40. TYPES OF GINGIVA The gingival is divided into three types: A)Free or unattached or marginal gingival B) Attached gingiva. C) Interdental papilla 40

41. A) FREE OR UNATTACHED OR MARGINAL GINGIVA:- • It is that part of the oral mucosa that surrounds the necks of the teeth and forms the free margin of the gingival tissue • It is differentiated apically from the attached gingival by the free gingival groove • The inner side of it forms the gingival sulcus • The free gingival mucosa is composed of stratified squamous epithelium that may be keratinized, parakeratinzed or sometimes nonkeratinized 41

42. Attached gingiva: • The attached gingiva lies between the free gingival groove and the alveolar mucosa • The junction of the attached gingiva and the alveolar mucosa is called mucogingival junction • In healthy mouth attached gingiva shows stippling (orange-peel appearance) which is a characteristic of this type of mucosa 42

43. Interdental Papillae : • Part which extends between two teeth up to the contact point is called interdental papillae. • It has a ‘facial side’ and a ‘lingual side’ . • It’s margins are concave. • Due to inflammation, interdental papillae looses it’s concavity 43

44. COL : • Connecting facial and lingual side of the interdental papilla (on proximal side) is an epithelial structure called COL. • It’s concave shape means, gingiva is healthy. • It becomes dome shaped, in gingival recession and inflammation. • It is covered by non keratinized stratified 44

45. Gingival fibres Bind attached gingiva to the alveolar bone & tooth. 4 groups: 1. Dentogingival fibres: from cervical cementum to lamina propria; most numerous. 2. Alveologingival fibres: from alveolar crest into Lamina Propria 3. Circular fibres: circle the tooth. 4. Dentoperiosteal fibres: from cementum into periosteum of alveolar crest & surface of alveolar bone. 45

46. MICROSCOPIC FEATURES OF GINGIVA Broadly speaking gingival is made up of epithelium and connective tissue. The gingival epithelium can be studied under three headings:- • Outer or oral epithelium • Sulcular epithelium • Junctional epithelium. 46

47. Oral epithelium: • Faces the oral cavity, is parakeratinised, shows rete pegs and connective tissue papillae Sulcular epithelium : • Faces the tooth without contacting it. Thin non-keratinised stratified squamous epithelium (no granulosum and corneum layers), extends from the coronal end of the junctional epithelium to the crest of the gingival margin. • Acts as a semi-permeable membrane. 47

48. Junctional epithelium : • Provides contact between gingiva & tooth. • Stratified squamous non-keratinised epithelium. • 3-4 cells thick in early life, increasing to 10-20 later. • Derived from the reduced enamel epithelium • Attachment to tooth: inner basal lamina • Attachment to gingival connective tissue: outer basal lamina 48

49. Hard palate • It is keratinized masticatory mucosa. • It is pink in color which is firmly attached to underlying structures Macro-Anatomy of hard palate Palatine gingiva: Adjacent directly to the teeth which is similar to the previously described gingiva but mucogingival junction is not present. 49

50. 50 Median palatine raphe: • Extends from the palatine papilla posteriorly. • Palatine papilla (incisive) is pear shaped & is formed of dense C.T. that contains the oral part of naso-palatine duct (this duct is lined by simple or pseudostratefied columnar epithelium rich in goblet cells). • In median palatine raphe, it is difficult to differentiate between lamina propria & submucosa. • Radiating from this raphe, transverse folds called palatine rugea which is formed of dense C.T. covered by epithelium.

51. 3- The anterolateral area (fatty zone) This area present between the raphe & the gingiva anteriorly.  Its lamina propria is fixed to periosteum by bands of fibrous C.T. dividing the submucosa into compartments containing fat cells. 4- The postero-lateral area (glandular zone) - Present posterior to the fatty zone. - The submucosa contains pure mucous glands.  The fatty and glandular zones act as cushion.  The C. T. of hard palate is thick anteriorly than posteriorly. Submucosa Fatty zone Glandular zone Epitheial rete pegs are tall & numerous Mucosa 51

52. Non-Keratinized Mucosa (Lining Mucosa) Present in areas not subjected to high levels of friction but is mobile & distensible Firmly attached to underlying muscles  Soft Palate  Lip  Cheek  Ventral Surface of tongue Loosely attached to underlying structures as bone, fascia or muscle  Floor of mouth  Vestibule  Alveolar Mucosa 52

53. • Thicker than masticatory mucosa. • Non keratinized. • flexible; withstand streching. • Interface with C.T is smooth. • Lamina propria is thicker with fewer collagen fibres(irregular). • Elastic fibres provide extensibility. • Attached to muscle by collagen & elastic fibres: retraction of mucosa during mastication. 53

54. Lip and cheek Vestibular fornix & alveolar mucosa Inferior surface of tongue & Floor of oral cavity Soft Palate Epithelium Non keratinized stratified squamous Non keratinized stratified squamous Non keratinized stratified squamous Non keratinized stratified squamous Lamina propria Short irregular papillae Short irregular papillae. • In the fornix mucosa loosely attached to the underlying structures. • In alveolar mucosa papilla may be totally missing • Floor of the mouth papillae are short. • On the inferior surface of tongue short but numerous Has distinct layer of elastic fibres separating it from sub mucosa. Connective tissue papillae few and short Sub mucosa Sub mucosa has strands of loose connective tissue with fat & small mixed glands A sub mucosa of loose connective tissue seen in alveolar mucosa. No muscle fibres present • Sub mucosa in floor of mouth has adipose tissue. • In inferior surface of the tongue a separate sub mucosa cannot be identified Relatively loose and contains plenty of mucous glands 54

55. Specialized Mucosa • Dorsal Surface of Tongue • The connective tissue binds the epithelium to the underlying skeletal muscle • The epithelium is modified, keratinized, stratified covered with papillae, which can be seen by naked eye The different papillae found on the dorsal surface of the tongue are: 1. Filliform papillae 2. Funginform papillae 3. Circumvallate papillae 4. Foliate papillae 55

56. 2 parts: • Anterior 2/3: 1st pharyngeal arch ;c/as body; TG nerve; papillary portion. • Posterior 1/3: 3rd pharyngeal arch;c/as base;IX nerve; lymphatic portion(lingual tonsil). • Separated by V shaped groove c/as sulcus terminalis. 56

57. Filiform papillae : • Anterior tongue. • Cone shaped structure. • C.T core covered with thick keratinized epithelium- velvety appearance of tongue. • Tough abrasive surface so function as masticatory mucosa. • Build up of keratin leads to elongation. • Increased keratinization leads to hairy tongue. • No taste buds. 57

58. Fungiform papillae : • Scattered between numerous filiform papillae at the tip of tongue. • Smooth, round structures; mushroom shaped. • Red- highly vascular C.T core & thin non keratinized epithelium. • Taste buds present on superior surface. 58

59. Circumvallate papillae • 8-12 in no. • Adjacent & anterior to sulcus terminalis. • Surrounded by deep, circular groove into which ducts of von ebner salivary glands open. • C.T core covered by keratinized epithelium superiorly. • Lateral walls- non keratinized epithelium & taste buds. 59

60. Foliate papillae: • Foliate papillae are located in the furrows along the posterior sides of the tongue • They may be lined with taste buds • They are not prominent in human beings 60

61. Papillae are mainly concerned with different taste sensations : Vallate papillae : Bitter Fungiform papillae : Sweet and salty Foliate papillae : Sour 61

62. Taste bud : ♦ Present in 1) All tongue papillae except filiform. 2) Soft palate. 3) Posterior surface of epiglottis. • They are intraepithelial structure, barrel or ovoid with rounded base resting on B.M & end with narrow opening toward the epithelial surface & called taste pore. Flattened small epithelial cells surround the taste pore. 62

63. Histology of the taste bud: • Each taste bud is composed of about 3 modified epithelial cell type. • Outer supporting (sustentacullar) cells arranged like layers of onion & are in contact with neighboring epithelial cells. • Inner supporting (sustentacular) cells, they are shorter & rode shape cells. 63

64. 64 • Taste cells (Neuroepithelial cells) they are 11-12 in number & present between the inner supporting cells. • These cells are slender with dark stained nucleus & apically stiff bristle-like process extends to the space beneath taste pore. • Nerve plexus present in C.T. below the taste bud, some fibers enter it & end in contact with the taste cells.

65. Lingual tonsil: - Present as small rounded or oval elevations due to aggregation of lymphatic nodules in underlying C.T known as lingual follicles. Histologically - Lingual follicles covered by St Sq Epith (non-keratinized) which extended down in many sites to form lingual crypt. The lymphatic tissue surrounds the crypt & composed of germinal centers & lymphatic tissue fills the spaces between these centers. 65

66. 66 - Ducts from underlying Weber mucous salivary gland open into the bottom of lingual crypt. - Lingual tonsil forms a part of the lymphatic ring between mouth & nose from one side & pharynx on the other side.

67. AGE CHANGES IN ORAL MUCOSA • Oral mucosa of an elderly patient has a smoother and dryer surface than younger patient, due to dry therapy or any systemic diseases. • Epithelium appears thinner histologically. • Flattening of epithelial ridges. • Reduction in no. of filiform papillae. • Langerhan’s cells become fewer with age, leading to decrease in cell mediated immunity.

68. 68 • Decrease in cellularity occurs in lamina propria with increase in collagen. • Sebaceous (Fordyce’s spots) glands of lips and cheeks increase with age. • Elderly post menopausal women, have symptoms such as dryness of mouth, burning sensations and abnormal taste.

69. CLINICAL CONSIDERATIONS 69 • The oral mucosa can change according to various factors, including smoking, age & disease. • Over 7% of the total number of cancers diagnosed in the United States are located in the oral & oropharyngeal areas. • The process of keratinization can be altered in cancerous & precancerous lesions such as leukoplakia.

70. 70 • Thinning of the epithelium occurs in relation to prosthetic devices covering the surface of the mucosa. • Changes in salivary flow- due to age, radiation or disease- disrupt the normal maturation & differentiation of the epithelial cell layers. • The healing capacity of the oral mucosa is greater than that of the skin. Orthognathic surgery to move segments of the mandible & maxilla can be performed using an intraoral approach to take advantage of these characteristics.

71. CONCLUSION 71 Oral mucous membrane maintains the integrity of the oral cavity in health & disease. Knowledge regarding the mucosa aids in detecting any changes from normalcy which would pave the way for diagnosing various disorders which affect the mucosa & thus, providing treatment for the same. Also as public health dentists, educating people regarding the detection of changes in the mucosa would help in early diagnosis & hence focus on prevention ensured.

72. 72 REFERENCES • S.N. Bhaskar. Orban’s, oral histology and embryology. 11th Edition, Mosby: 1998; p – 345-385 • Neville BW, Damm DD, Allen CM, Bouquot JE. Oral and maxillofacial pathology, 2nd edition. Philadelphia : W.B. Saunders ; 2002. • Richard Tencate, Oral histology development, structure and function. 5th edition, 1998 : p 345-385. • Carranza F.A., Michael G. Newman. Clinical peridontology 8, 9,10th edition

Oral mucous membrane - Oral mucosa

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Oral mucous membrane - Oral mucosa