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oral bio > mucous membrane > Flashcards

mucous membrane Flashcards

1
Q

What is oral mucosa?

A

mucous membrane lining the oral cavity and coated by serous and mucous secretions

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2
Q

What does the oral mucous membrane histologically consist of?

A
  • surface epithelium
  • CT (lamina propria)
  • junction between epithelium CT (basement membrane)
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3
Q

Is there submucosa in the oral mucous membrane?

A

sometimes

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4
Q

What is found under the hard palate?

A

maxilla bone

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5
Q

Is there bone under the soft palate?

A

no

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6
Q

What is the vestibule?

A

a gap that separates the lip and the mucosa

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7
Q

What are the 2 sides of the tongue called?

A
  • superior surface (dorsum)
  • inferior surface (ventral)
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8
Q

What is found under the gingiva?

A

alveolar mucosa (red coloured area)

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9
Q

What is under the tongue?

A

floor of the mouth

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10
Q

What covers alveolar bone?

A

alveolar mucosa

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11
Q

What is the oral mucosa classified into?

A
  • masticatory mucosa (keratinised mucosa)
  • lining mucosa (non-keratinised mucosa)
  • specialised mucosa
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12
Q

What are the masticatory mucosa?

A
  • hard palate
  • gingiva
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13
Q

What are the lining mucosa classified into?

A
  • firmly attached
  • loosely attached
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14
Q

What is the firmly attached lining mucosa?

A
  • soft palate
  • inferior surface of tongue
  • lip
  • cheek
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15
Q

What is the loosely attached lining mucosa?

A
  • alveolar mucosa
  • vestibular formix
  • floor of the mouth
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16
Q

What is the specialised mucosa?

A

dorsal surface of the tongue

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17
Q

What is the function of the lining mucosa?

A

protective lining

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18
Q

Why is the alveolar mucosa loosely attached?

A

to allow movement of the lip

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19
Q

Why is the vestibular formix (oral vestibule) loosely attached?

A

to allow movement of the cheek

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20
Q

Why is the floor of the mouth loosely attached?

A

to allow movement of the tongue

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21
Q

All of the gingiva is keratinised, except…

A
  • gingival col
  • gingival sulcus
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22
Q

Why is the dorsum of the tongue a specialised type of mucosa?

A

it contains different types of papillae, taste buds and lingual tonsils

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23
Q

What is the colour of gingiva?

A

pink and pigmented in coloured races

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24
Q

What is the mucogingival junction (healthy line)?

A

a scalloped line that separates gingiva from alveolar mucosa

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25
Q

What happens if the healthy line is absent?

A

there is gingivitis

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26
Q

Where is the healthy line present?

A

facial aspects of lower and upper jaws, lingual, aspect of lower jaw but not on palatal aspect of upper jaw

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27
Q

What is gingiva divided into?

A
  • free gingiva
  • gingival sulcus
  • attached gingiva
  • inter-dental papilla
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28
Q

What separates free gingiva from the attached gingiva?

A

free gingival groove

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29
Q

What causes the formation of free gingival groove?

A

functional impacts upon free gingiva

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30
Q

Where is the free gingiva found?

A

extends along cervical level of the tooth at labial, buccal and lingual surfaces

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31
Q

Is free gingiva moveable?

A

yes, it if freely moveable

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32
Q

What is the gingival sulcus?

A
  • shallow groove
  • lined by non-keratinised epithelium
  • its bottom present at point of separation of attached epithelium from the tooth
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33
Q

What happens if the gingival sulcus is very shallow?

A

build up calculus and bacteria

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34
Q

What is the depth of gingival sulcus and how is it measured?

A
  • from 0-6mm
  • average is 1.8mm
  • measured by a periodontal probe
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35
Q

Is attached gingiva moveable?

A

no

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36
Q

What is attached gingiva?

A
  • attached to cementum or periosteum and extends from the free gingival groove to muco-gingival junction which separates the attached gingiva from alveolar mucosa
  • surface shows stippling which is due to functional adaptation to mechanical impacts
    has roughness to attach food for masticatory function
  • stippling correspond to heavier epithelial rete pegs
  • depressed between eminencies of sockets forming grooves called inter-dental grooves
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37
Q

What is the cause if there is absence of stippling in attached gingiva?

A

inflammation

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38
Q

What is inter-dental papilla?

A
  • fills inter-proximal spaces between adjacent teeth below the contact area
  • have a tent shape labially and buccally
  • wedge shape lingually where the base corresponds to a line connecting the margin of the gingiva at the centre of one tooth to the centre of the next one and the apex tapers to the contact area
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39
Q

What is gingival col?

A

inter-dental gingival tissue found in depression between two peaks of inter-dental papilla (labial and lingual peaks) and is non-keratinised

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40
Q

What are the epithelial layers of gingiva (microanatomy)?

A
  • stratum basale
  • stratum spinosum
  • stratum granulosum
  • stratum cornium
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41
Q

What are the cells at stratum granulosum capable of?

A

produce DNA and divide by mitosis to give new cells just sufficient to match those lost by desquamation at surface

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42
Q

What are the type of cells and their number of layers in stratum basal?

A

one layer of high cuboidal (or columnar) cells

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43
Q

The basal cells are connected to each other by…

A

desmosomes

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44
Q

basal cells are connected to the basement membrane by…

A

hemidesmosomes

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45
Q

What are rete pegs?

A
  • down growth of epithelium to C.T.
  • they interdigitate with C.T. papillae
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46
Q

What are the rete pegs of the gingiva like?

A
  • irregular
  • tall
  • thin (slender)
  • numerous
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47
Q

What are the shape o cells in stratum spinosum?

A

polyhedral shaped cells (small with wide intercellular spaces)

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48
Q

What are the cells found in stratum granulosum?

A
  • flat cells
  • cells contain basophilic granules called keratohyaline granules
  • small nucleus
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49
Q

What is the cornfield layer formed of?

A

keratinised squamae which are larger and flatter than granular cells

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50
Q

What are the types of gingival epithelium according to type of keratinisation?

A
  • orthkeratinised epithelium 15% (where the nuclei and other organelles disappeared)
  • parakeratinised epithelium 75% (sratum corneum retains pyknotic nucleus or remnants of nuclear material (cell organelles))
  • non-keratinised epithelium 10% (stratum corneum is absent)
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51
Q

Where is non-keratinised epithelium foundin gingiva?

A
  • gingival sulcus
  • gingival col
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52
Q

What are keratinocytes?

A

cells found in stratum basale, stratum granulosum and stratum spinosum

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53
Q

Wat are the functions of keratinocytes?

A

make keratin when needed

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54
Q

What does the reticular layer contain?

A

collagen fibers arrangd in a loose network with free agirophilic fibers

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55
Q

What does the deep layer contain?

A

dense collagen fibers arranged in network

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56
Q

What do the desmosomes consist of?

A
  • thickening of adjacent cell membrane (2 adjacent cells)
  • a pair of attachment plaque (2 adjacent cells)
  • tonofilaments
  • extracellular structure (act as glue)
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57
Q

What are found in hemidesmosomes?

A
  • lamina densa
  • basal lamina
  • anchoring fibril
  • lamina lucida
  • reticular fibers (lamina)
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58
Q

What do hemidesmosomes consist of?

A
  • thickening of cell membrane
  • tonofilaments
  • extracellular structure
  • single attachment plaque
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59
Q

Are the cells in stratum spinosum protein forming cells?

A

yes

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60
Q

What are odland’s bodies?

A
  • other name: keratinosomes
  • membrane coating granules
  • present in superficial layer of spinous cell layer or in lower granular cell layer
  • have internal lamellated structure
  • originate from golgi system
  • responsible for thickening of cell membrane which occurs during keratinisation
  • may form an intercellular agglutinating material
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61
Q

What is filaggrin?

A

protein of keratohyaline granules (matrix between keratin around tonofilaments

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62
Q

What are non- keratinocytes?

A
  • pigment cells
  • langerhams cells
  • merkel cells
  • inflammatory cells
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63
Q

What are pigment cells and their characteristics?

A
  • melanocyte or melanoblast
  • found in basal and para basal cell layer
  • pigmentation ranges from light brown to black present as granules in the cytoplasm of the cells
  • cells are derived from neural crest cells
  • cells are larger than epithelial cells and they send large branched process in intercellular spaces of other keratinocytes
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64
Q

Where does pigmentation of gingiva occur mostly?

A

attached gingiva beneath inter-dental papilla

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65
Q

By electron microscope, what do melanocytes lack?

A

tonofilaments and desmosomes

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66
Q

Why are melanocytes termed clear dendritic cells?

A

cells appear clear with H&E stain

67
Q

What do melanocytes need for pigment formation?

A

tyrosinase enzyme which is demonstrated by dopa stain

68
Q

What is it called when melanin is stored in epithelial cells?

A

melanophore

69
Q

What is it called when melanin is stored in C.T.?

A

melanophage

70
Q

What are langerhans cells and what are their characteristics?

A
  • dendritic cell
  • present in upper layers of oral epithelium
  • may also be found in deeper layers
  • contain langerhans granules
  • derived from bone marrow
  • cells are demonstrated by gold chloride stain
  • have a role in contact allergic conditions
71
Q

By electron microscope, langerhans cells lack…

A
  • tonofilaments
  • desmosomes
72
Q

What are langerhans cells described as?

A
  • degenerated melanocyte
  • intra-epithelial macrophages
  • neural element
  • controlling epithelial cell division
73
Q

What are merkel cells and their characteristics?

A
  • not dendritic cells
  • clear cells present basally in oral epithelium
  • neural crest in origin
  • nerve fiber is seen to be associated with the cell (responds to touch or pressure sensation)
  • contain membrane-bound granules that liberate a transmitter substance across the synapse like cleft to adjacent nerve fiber
74
Q

By electron microscope, Merkel cells contain little…

A
  • tonofilaments
  • desmosomes
75
Q

What are inflammatory cells and their characteristics?

A
  • lymphocytes (polymorph-nuclear leukocytes)
  • present as ransient cells in varies levels of oral epithelium
76
Q

What is the junction of epithelium and C.T. by light microscope?

A

basement membrane

77
Q

What is the junction of epithelium and C.T. by electron microscope?

A

basal lamina

78
Q

What does the basal lamina consist of?

A
  • clear zone (lamina lucida) found just below epithelial cells
  • dark zone (lamina densa) found below lamina lucida and consists of granular and filamentous material
79
Q

What are the dark zone and clear zone products of?

A

basal cells (epithelial in origin)

80
Q

What happens in the region of desmosomes?

A

anchoring fibers interdigitate with collagen fibers of C.T.

81
Q

What is the palate characterised by?

A

presence of transverse folds called palatine rugae which is formed of dense C.T. covered by epithelium

82
Q

What is the palatine gingiva?

A

area adjacent directly to the teeth which is similar to the gingiva but mucogingival junction is not present

83
Q

What is the median palatine raphe?

A
  • extends from palatine papilla posteriorly
  • palatine papilla is pear shaped
  • difficult to differentiate between lamina propria and submucosa
84
Q

Where is the fatty zone found in the palate?

A
  • anterolateral area
  • area present between raphe and gingiva anteriorly
85
Q

Where is the glandular zone found in the palate?

A
  • posterolateral area
  • posterior to fatty zone
86
Q

What are the rete pegs like for the palate?

A
  • short
  • broad
  • irregular
  • numerous
87
Q

Where is the fatty and glandular zone found in the palate?

A

submucosa

88
Q

What does the lining mucosa have?

A
  • thick non-keratinised epithelium
  • submucous layer
  • thin lamina propria
89
Q

What are the layers of lining mucosa (non-keratinised)?

A
  • stratum basal
  • stratum intermedium
  • stratum superficial
90
Q

What are the characteristics of polyhedral cells in lining mucosa?

A
  • small intercellular spaces
  • small intercellular bridges
  • no prickly appearance
91
Q

What are odland bodies like in lining mucosa?

A

different size and shape

92
Q

Is there cornfield layer in lining mucosa?

A

no

93
Q

Where are the gingival fibers of the gingiva present?

A

on level of attached gingiva

94
Q

What do gingival fibers arise from?

A

cementum and alveolar crest and radiate to the papillary layer of the gingiva to give strength to the gingiva

95
Q

What are fibers classified functionally into?

A
  • dentogingival group
  • alveologingival group
  • circular group
  • dentoperiosteal group
96
Q

What is dentogingival group?

A
  • main group
  • extends from cervical cementum to lamina propria
97
Q

What is alveologingival group?

A

extends from alveolar crest to lamina propria

98
Q

What is circular group?

A

small group that encircles the tooth and interlaces with other fibers so it is neither attached to the cementum nor to he alveolar bone

99
Q

What is dentoperiosteal group?

A

extends from cementum then go over the bone crest and inclines apically between periosteum of alveolar bone (where it is inserted)

100
Q

What is the fatty zone’s lamina propria fixed to?

A

periosteum by bands of fibrous C.T. fividing the submucosa into compartments containing fat cells

101
Q

What gland does the submucosa contain?

A

pure mucous glands

102
Q

What does the submucosa (fatty zone and glandular zone) act as?

A

cushion

103
Q

What does stratum superficial contain?

A
  • nucleated flat cells
  • desquamated as cornfield layer
  • keratohylaine granules cause thickening of membrane (if present)
104
Q

What is the difference in lamina propria between keratinised and non-keratinised epithelium?

A
  • thinner than keratinised mucosa
  • epithelial rete pegs and C.T. papillae are low or may be entirely missing
105
Q

Can there be minor salivary glands found in te submucosa of non-keratinised epithelium?

A

yes

106
Q

What is lining mucosa (firmly attached)?

A

mucous membrane covering muscles and they are firmly attached to them

107
Q

What are some characteristics of the inferior surface of the tongue?

A
  • covered by thin non-keratinised epithelium with short and numerous C.T. papillae
  • the submucosa can not be differentiated as a separate layer where it connects the mucous membrane to the C.T. surrounding tongue muscles
108
Q

What are some characteristics of the soft palate?

A
  • its epithelium is continuous with that of the hard palate but non-keratinised so between them there is a healthy line
  • the epithelium that forms the nasal side is pseudostratified columnar ciliated epithelium with goblet cells
  • highly vascularised and red in colour
  • lamina propria is thin with few and short papillae
  • a continuous layer of elastic fibers separating lamina propria from submucosa
  • submucosa contains fat cells and mucous glands
109
Q

What happens if the healthy line is not present?

A

indicates inflammation

110
Q

What are some characteristics of the cheek?

A
  • non-keratinised stratified squamous epithelium
  • C.T. papillae are short, irregular and with few elastic fibers
  • in submucosa and between the buccinator muscle bundles, small mixed salivary glands are present
  • sometimes isolated sebaceous glands may be present in C.T. lateral to the mouth corner called Fordyce granules or spots considered anomaly
  • the firm attachment of the cheek mucosa to the muscle presents its biting especially during mastication
111
Q

How many surfaces is the lip formed of?

A
  • lining mucosa
  • transitional zone
  • skin side
112
Q

What are the characteristics of the lining mucosa of the lip?

A

similar to that of cheek except
- submucosa contains fat cells and mixed salivary glands on the surface of orbicularis oris muscle
- no Fordyce spots

113
Q

What are the characteristics of the transitional zone of the lip?

A
  • lying between lining mucosa and skin side of the lip
  • present only in human race and represented as red zone called vermillion border
  • covered by stratified squamous epithelium with thin layer of keratin
  • C.T. papillae are numerous, long and densely arranged, these deep papillae carry large capillary loops so the thin layer of epithelium permits the red colour of blood
  • one or two sebaceous glands may be present
114
Q

What are the layers found in the skin side of the lip?

A
  • epidermis
  • dermis
115
Q

What ae the characteristics of the epidermis found in the skin side of the lip?

A
  • formed of stratified squamous keratinised epithelium with hair, sweat glands and sebaceous glands
  • epithelium is similar to that of keratinised mucosa except that; there is additional layer present between granular cell layer and the keratinised layer called stratum lucidum
  • stratum lucidum is a pale translucent layer formed of 2-3 layers of flat cells with very small nucleus and indistinct boundaries
  • the cells permeated with elaidin oil which arise from the liquefaction of keratohyaline granules
  • melanoblasts present in between the basal cell layer (in black races they may fill all the epithelial layers and even the C.T. papilla)
116
Q

What are the uses of elaidin oil?

A
  • protection
  • moisturisation of skin
117
Q

Is there hair follicle in the skin side of the lip?

A

yes

118
Q

What are some characteristics of hair follicle that is found in the epidermis of the skin side of the lip?

A
  • has a shaft projected above the surface and root embedded in an invagination of epidermis called hair follicle
  • root terminated in an expansion called hair bulb
  • an upward invagination of C.T. to hair bulb is called hair (C.T.) papilla
  • 1 or 2 sebaceous glands open in te neck of the hair follicle
  • sweat glands may also be present and consist of coiled secretory part and duct which formed of single cuboidal or pyramidal cells with large nucleus
  • myoepithelial cells present between the basement membrane and the secretory cells
119
Q

What type of gland is sebaceous gland?

A

holocrine gland that secretes oily secretions by degeneration of cells

120
Q

What type of gland is sweat gland?

A

apocrine (secretion from apex of cells) and merocrine (secretion done by exocytosis)

121
Q

What ae the characteristics of the dermis found in the skin side of the lip?

A
  • formed of dense C.T. with few and short papillae
  • formed of reticular layer and papillary layer
122
Q

What does the reticular layer consist of?

A
  • collagen fibers arranged in network
  • less number of cells
  • contain think elastic fibers
123
Q

What does the papillary layer consist of?

A
  • irregularly arranged
  • more cells than reticular layer
  • thick elastic fibers
124
Q

What are the characteristics of alveolar mucosa?

A
  • covered in stratified squamous non-keratinised epithelium
  • C.T. papillae are short or even missing
  • collagen fibers of lamina propria are regularly interwoven
  • submucosa may contain small mixed salivary glands
  • elastic fibers are thin in lamina propria and thick in submucosa
125
Q

What are the characteristics of vestibular formix?

A
  • permits movement of the lip and cheek and covered by stratified squamous non-keratinised epithelium
  • C.T. papillae are short and few
  • labial frenum (median and lateral) is folds of mucous membrane containing loose C.T. with no muscle fibers
  • no submucosa is present
126
Q

What are the characteristics of floor of mouth?

A
  • covered by thin stratified squamous non-keratinised epithelium
  • C.T. papillae are few and short
  • submucosa contains fat cells
  • sublingual and submandibular ducts are present near the covering mucosa in the sublingual folds
127
Q

where is specialised mucosa found?

A

present on the dorsal surface of the tongue which is divided by V shaped sulcus terminalis into papillary part (anterior 2/3) and lymphatic part (posterior 1/3)

128
Q

What is found on the anterior 2/3 of the tongue?

A

papillae and taste buds (special sensation)

129
Q

What does the lymphatic ring consist of?

A
  • palatine tonsil
  • lingual tonsil
130
Q

What are the types of tongue papillae?

A
  • filiform
  • fungiform
  • circumvallate
  • foliate
131
Q

What are the characteristics and location of filiform papillae?

A
  • found on dorsal surface of the tongue as high narrow conical structures that are arranged in parallel rows and near the posterior 1/3 the rows become parallel to sulcus terminalis
  • composed histologically from central core of C.T. covered by keratinised epithelium
  • primary papilla sends up 1-2 secondary papillae where the epithelium over them become hornified
  • does not contain taste buds
  • function is movement of food
132
Q

What are the characteristics and location of fungiform papillae?

A
  • present on dorsal surface of tongue in between filiform papillae
  • mushroom-like narrow at the base with smooth rounded top
  • numerous at tip of tongue
  • histologically is composed of central core of primary C.T. papilla and covered by stratified squamous non-keratinised epithelium
  • secondary C.T. papillae make the blood vessels near to the surface epithelium so the papilla appears red in colour
  • contains 1-2 taste buds
  • papillae on tip of the tongue is responsible for sweet sensation
  • papillae on the lateral borders of the tongue responsible for salt sensation
  • chorda tympani (branch of facial nerve) is responsible for these sensations
133
Q

What are the characteristics and location of circumvallate papillae?

A
  • present on dorsal surface of tongue anterior to sulcus terminalis
  • do not protrude above the surface of the tongue but embedded in the tongue and surrounded by deep trough which contains many teste buds
  • in the C.T. in the base of the trough von Ebner salivary gland is present
  • papilla has narrow base and wide surface with central core of C.T. which sends secondary C.T. papillae to the stratified squamous non-keratinised epithelium
  • responsible for the bitter sensation by the glossopharyngeal nerve
134
Q

What are the functions of von Ebner salivary glands?

A
  • cleanse the food debris in the trough to prepare the taste bud for new taste sensation
  • dissolving the food to help the taste function
  • in infant secretes lipase enzyme
  • in infant secretes enzyme
135
Q

What are the characteristics and location of foliate papillae?

A
  • present as sharp parallel clefts on the lateral sides of sulcus terminalis
  • surrounded by troughs in which von Ebner salivary glands open in it
  • contains taste buds
  • responsible for sour sensation by the glossopharyngeal nerve
136
Q

Where can taste buds be found?

A
  • soft palate
  • al tngue papillae except filiform
  • posterior surface of epiglottis
137
Q

What is the shape of taste buds?

A

ovoid with rounded base toward C.T. and pointed end at the outer surface (taste pores)

138
Q

What is the histology of taste buds?

A
  • outer supporting (sustentacular) cells arranged like layers of onion and are in contact with the epithelial cells
  • inner supporting (sustentacular) cells that are rod shaped with basal nucleus
  • neuroepithelial cells (receptors of taste stimuli), they are 10-12 in number and present between inner supporting cells
  • neuroepithelial cells are slender with basally dark stained nucleus and apically stiff bristle-like process (taste hair) extending to the space beneath the taste pores
  • about 80 microns in height ad 40 microns in width
  • nerve plexus present in C.T. below the taste bud, some fibers enter it and end i contact with the taste cells
139
Q

What are other names for the posterior 1/3 of the tongue?

A
  • root part
  • lymphatic part
  • pharyngeal part
140
Q

What is the structure of lingual tonsils?

A

small rounded or oval elevations due to aggregation of lymphatic nodules in the underlying C.T. known as lingual follicles

141
Q

What is the histology of lingual follicles?

A
  • covered by stratified squamous non-keratinised epithelium which extends down in many sites to form lingual crypt
  • the lymphatic tissue composed of germinal centers and lymphatic tissue fills the space between these centers (lymphocytes and plasma cells)
  • ducts from underlying Weber mucous salivary glands open into the bottom of the lingual crypt
  • lingual tonsil forms a part of the lymphatic ring between mouth and nose from one side and the pharynx on the other side
142
Q

What is dentino-gingival junction?

A

junction between tooth and gingiva (both epithelium and lamina propria)

143
Q

What is attached epithelium (junctional epithelium)?

A

epithelial part of the gingiva making the junction with the tooth

144
Q

What is the length of junctional epithelium?

A
  • 1-3mm extending from the bottom of the gingival sulcus towards CEJ (PDL) or below it
  • length of junctional epithelium is equal to the distance between apical end of attached epithelium and the crest of alveolar bone
145
Q

What is the histogenesis (development) of dento-gingival junction?

A
  • after enamel formation, the ameloblasts secrete primary enamel cuticle and develop hemidesmosomes to attach the reduced enamel epithelium to the surface of enamel
  • at time of eruption, the reduced enamel epithelium will secrete desmolytic enzymes causing degeneration of the C.T. present between it and the oral mucosa
  • the outer layer of the reduced enamel epithelium and the basal layer of oral epithelium will proliferate into the degenerated C.T. to form a mass of cells over the erupting tooth (epithelial plug)
  • cell death in the middle of the epithelial plus leads to the formation of epithelial lined canal through which tooth will erupt without haemorrhage
  • once the tip of the crown appears in the oral cavity, reduced enamel epithelium will be called primary attached epithelium and the shallow groove present between the tooth and the gingiva is called gingival sulcus or gingival crevice
146
Q

Why does the reduced enamel epithelium attach to the surface of enamel?

A

prevents food from entering P.L.

147
Q

What kind of basement membrane is found in dento-gingival junction?

A

double basement membrane
- external (toward C.T.)
- internal (toward tooth)

148
Q

What is the histological structure of DGJ?

A

attached epithelium is formed of stratified squamous non-keratinised epithelium which at first is formed of 3-4 layers and gradually increase with age to 10-30 layers coronally and 1-2 layers apically

149
Q

What can be seen in DGJ through light microscope?

A
  • the basal cell layer is formed of cuboidal cells with their long axes perpendicular to the tooth surface and resting on smooth basement membrane
  • above the basal layer, the cells are flat with a wide intercellular spaces and less desmosomes (to allow defensive cells to kill bacteria), they are arranged obliquely until the superficial cells become parallel to the tooth surface
  • attachment epithelium is permeable so neutrophil, leukocytes and mononuclear cells are present
150
Q

What indicates inflammation when looking at DGJ under a light microscope?

A

irregular basement membrane

151
Q

What can be seen in DGJ through electron microscope?

A
  • basal cels appear with normal basal lamina (external basal lamina) and hemidesmosomes where the basal lamina between the attachment epithelium cells and enamel or cementum is called internal basal lamina and also associated with hemidesmosomes
  • flat cells lack the number of tonofilaments and keratinosomes found in cells in other regions of oral epithelium
152
Q

What is the shift of DGJ (stages of passive eruption)?

A
  • when the tooth first erupts, the enamel is almost covered by epithelium
  • by further eruption and gingival recession, the more the tooth will be exposed in the oral cavity
153
Q

What is active eruption?

A

actual movement of teeth towards occlusal plane

154
Q

What is passive eruption?

A

gradual exposure of crown by separation of attached epithelium from the tooth surface (gingiva goes down with age)

155
Q

What is anatomical crown?

A

part of the tooth covered by enamel

156
Q

What is clinical crown?

A

part of the tooth that appears in the oral cavity

157
Q

What is primary attachment epithelium?

A

its cells originated from reduced dental epithelium and attached to the tooth surface by primary enamel cuticle

158
Q

What is secondary attached epithelium?

A
  • when attached epithelium is replaced by oral epithelium
  • attached to tooth by secondary enamel cuticle
159
Q

What are the 4 stages of passive eruption?

A
  • first and second stages are considered normal
  • third and fourth stages may be normal or pathologic
160
Q

What happens in the first stage of passive eruption?

A
  • occurs in the primary teeth until one year before shedding in the permanent teeth till 20-30 years
  • coronal end of primary attachment epithelium present on the enamel and the apical end on the cemento-enamel junction
  • clinical crown is less than anatomical crown
161
Q

What happens in the second stage of passive eruption?

A
  • occurs till the age of 40 years or even later
  • coronal end is still on the enamel and the apical end on the cementum
  • the clinical crown is less than the anatomical crown
162
Q

What happens in the third stage of passive eruption?

A
  • transient stage
  • coronal end present at the CEJ and the apical end on the cementum
  • clinical crown is equal to the anatomical crown
163
Q

What happens in the fourth stage of passive eruption?

A
  • from 60 years and later
  • pathological stage
  • coronal and apical ends are present on the cementum
  • clinical crown is longer than anatomical crown
164
Q

What is the epithelial attachment in DGJ (mode of attachment)?

A
  • formed of basal lamina to which hemidesmosomes are attached
  • attachment is so strong that an attempt to detach the gingiva from the tooth surface, the junctional epithelium will tear rather than peel off
  • at first, the epithelium attachment is secreted by ameloblasts and called primary enamel cuticle, which attaches the primary attachment epithelium (originated from the reduced enamel epithelium) to the tooth surface
  • later the primary attachment epithelium is replaced by the oral epithelium and called secondary attachment epithelium where it secretes secondary enamel cuticle to attach it to the tooth
  • when attachment epithelium is present on enamel and cementum, the cuticle is formed of 2 parts, enamel and cemental cuticles so it can be called dental cuticle

oral bio (5 decks)

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