JUNCTIONS IN THE ORAL

MUCOSABYBY

DR. Fawzy DarweeshDR. Fawzy DarweeshAssistant professor of Oral Assistant professor of Oral

BiologyBiologyFaculty of DentistryFaculty of DentistryMansoura UniversityMansoura University

• Three junctions :1. The mucocutaneous

(between the mucosa and skin)

2. The mucogingival (between the alveolar mucosa and attached gingiva)

3. The dentogingival (between the tooth and gingiva)

Mucocutaneous JunctionMucocutaneous Junction Is the transitional zone between Is the transitional zone between

the skin of the lip and its the skin of the lip and its mucous membrane. mucous membrane.

It is called the It is called the red zonered zone or or vermilionvermilion borderborder. .

The LipThe Lip

Skin SideSkin Side

Vermilion zoneVermilion zone

Mucous Membrane Mucous Membrane sideside

Vermilion border

MMSkin

The lipThe lip Made of skletal muscles Made of skletal muscles

(orbicular oris).(orbicular oris). The skin is coved by a The skin is coved by a

moderately thick keratinized st. moderately thick keratinized st. squ. epith. with squ. epith. with thickthick stratum stratum corneum (epiderms).corneum (epiderms).

Dermis : composed of C.T. rich in Dermis : composed of C.T. rich in elastic fibers and blood elastic fibers and blood capillaries. capillaries.

The papillae: The papillae: fewfew and and shortshort. . Many Many sebaceous glands sebaceous glands are found are found

in connection with in connection with hair follicleshair follicles. . Sweat glands Sweat glands occur between occur between

them. them.

The epithelim of the mucous The epithelim of the mucous membrane of the lip is not membrane of the lip is not keratinized (lining mucosa) .keratinized (lining mucosa) .

The transitional zone is characterized by:The transitional zone is characterized by:1. Numerous long papillae, reaching deep 1. Numerous long papillae, reaching deep

into the epith. into the epith. 2. The papillae carrying large capillary 2. The papillae carrying large capillary

loops. loops. 3. The papillae are rich in sensory nerve 3. The papillae are rich in sensory nerve

endings.endings.4. Contains only occasional sebaceous 4. Contains only occasional sebaceous

glands (requires moistening by the glands (requires moistening by the tongue). tongue).

5. No sweat glands or hair follicles. 5. No sweat glands or hair follicles.

This zone is covered with This zone is covered with partially partially keratinized st. squ. keratinized st. squ. epith.epith.

The The LipLip

Skin SideSkin Side

VermilioVermilion zonen zone

Mucous Mucous Membrane Membrane

sideside

Sebaceous glands

salivary glands

epidermis( stratum lucidum)

Few & short papillaeSweat & sebaseous

Glands(pale yellow spots)

thick nonkeratinized st. sq. epitheliumdense collagen f.

minor salivary glands

Thin epith, thin keratin layer,high C.T. papillae, many b.v,.

and sensory nerve endings (occasional Fordyce’s spots).

Skin Skin SideSideepidermis

( stratum lucidum)eleidin

Sweat & sebaseous glands

Sweat glands

A- Hair follicles B- Sebaceous glandsC- Sweat glands

The LipThe LipSkin SideSkin Side

epidermis(stratum lucidum) Eleidin•Hair follicles •Sweat glands• Sebaseous glands

Hair papillaHair root

Vermilion zone

(red zone)Thin epith, thin keratin layer,high C.T. papillae, many b.v., and n. endings.

Keratinized epith. of the skin below the vermilionzone of the lip

Mucous Membrane SideMucous Membrane Sideof the Lipof the Lip

thick nonkeratinized st. sq. epithelium(A)dense collagen f.(B)

minor salivary glands(C)(labial glands)

Sebaceous glands

(occasional Fordyce’s spots)

Mucogingival JunctionMucogingival Junction Clinically: identified byClinically: identified by1. The mucogingival groove.1. The mucogingival groove.2. Change from bright pink 2. Change from bright pink

(alveolar mucosa) to pale (alveolar mucosa) to pale pink (gingiva). pink (gingiva).

Mucoging.junction

Attachedgingiva

Alveolarmucosa

Histologically ;Histologically ; The attached gingiva is The attached gingiva is

keratinized or parakeratinized.keratinized or parakeratinized. The lamina propria contains The lamina propria contains

numerous collagen bundles numerous collagen bundles attaching the tissue to attaching the tissue to periosteum (stippling periosteum (stippling appearance).appearance).

The alveolar mucosa has a The alveolar mucosa has a thicker, nonkeratinized epith.thicker, nonkeratinized epith.

Overlying a loose lamina propria Overlying a loose lamina propria with numerous with numerous elastic fibers elastic fibers extending into the extending into the thick thick submucosasubmucosa..

These elastic fibers return the These elastic fibers return the alveolar mucosa to its original alveolar mucosa to its original position after distension by the position after distension by the labial muscle during labial muscle during msatication and speech. msatication and speech.

Mucogengival junction(keratinized gingiva – right ; nonkeratinized mucosa – left)

Dentigingival JunctionDentigingival Junction Is that region where the oral Is that region where the oral

mucosa of the gingiva mucosa of the gingiva (epithelium) meets the surface (epithelium) meets the surface of the tooth. of the tooth.

Dento-gingival Dento-gingival JunctionJunction

and and Gingival Sulcus Gingival Sulcus

This junction is the principal This junction is the principal seal between the oral cavity and seal between the oral cavity and the underlying tissues. the underlying tissues.

It is derived from the It is derived from the reduced E. reduced E. epithepith..

Histogenesis of Dento-gingival Junction

The floor of the sulcus and the The floor of the sulcus and the epith. cervical to it, which is epith. cervical to it, which is applied to the tooth surface is applied to the tooth surface is termed termed junctional (attachment) junctional (attachment) epithelium. epithelium.

The junctional epith. is The junctional epith. is nonkeratinizednonkeratinized..

It consists of flattened cells It consists of flattened cells aligned parallel to the tooth aligned parallel to the tooth surface (from 1-4 layers apically surface (from 1-4 layers apically to 15-30 layers coronally).to 15-30 layers coronally).

Gingival Sulcus & Dentogingival Gingival Sulcus & Dentogingival JunctionJunction

The epithelium has a smooth The epithelium has a smooth C.T. interface where a basal C.T. interface where a basal lamina has assoicated lamina has assoicated hemidesmosomeshemidesmosomes. .

Furthermore, a basal lamina and Furthermore, a basal lamina and hemidesmosomes are found hemidesmosomes are found between the junctional epithelial between the junctional epithelial cells and the enamel (or cells and the enamel (or cementum). cementum).

The cells of the junctional epithelium The cells of the junctional epithelium immediately adjacent to the tooth attach immediately adjacent to the tooth attach themselves to the enamel or cementum by themselves to the enamel or cementum by hemidesmosomes within the cellhemidesmosomes within the cell and aand a basal basal laminalamina produced by the epithelial cells.produced by the epithelial cells.

Mode of Attachment of DGJ“ Epithelial Attachment”

The basal lamina in contact with The basal lamina in contact with the tooth is termed the tooth is termed the internal the internal basal lamina. basal lamina.

The other surface of the junctional The other surface of the junctional epithelium in contact with the lamina epithelium in contact with the lamina propria is the normal basal lamina propria is the normal basal lamina and and termed termed the external basal lamina.the external basal lamina.

So the junctional epithelium is therefore So the junctional epithelium is therefore unique in having unique in having two basal laminaetwo basal laminae. .

Int. B. L.

Ext. B. L.

E

Inflammatory cells (neutrophils) Inflammatory cells (neutrophils) are present in the C.T. supporting are present in the C.T. supporting the epith. of the dentogingival the epith. of the dentogingival junction. junction.

These cells continually migrate These cells continually migrate into the junctional epith. into the junctional epith.

They pass between the epith. cells They pass between the epith. cells to appear in the gingival sulcus to appear in the gingival sulcus and in oral fluid. and in oral fluid.

Shift of Dentogingival Junction Shift of Dentogingival Junction The position of the gingiva on The position of the gingiva on

the tooth surface changes the tooth surface changes during eruption and a gradual during eruption and a gradual exposure of the crown follows. exposure of the crown follows.

The actual movement of the The actual movement of the tooth toward the occlusal plane tooth toward the occlusal plane is termed is termed activeactive eruptioneruption. .

The separation of the The separation of the attachment epith. from the E. is attachment epith. from the E. is termed termed passive eruptionpassive eruption ( (thethe tooth statictooth static).).

Passive eruption has four Passive eruption has four stages.stages.

The first two may be The first two may be physiologicphysiologic and the last two may be and the last two may be pathologicpathologic..

First StageFirst Stage The The bottombottom of the g. sulcus of the g. sulcus

remains in remains in EE. and the . and the apical end apical end of attach. E. stays at of attach. E. stays at CEJCEJ..

Persists to the age of 20-30 yrs.Persists to the age of 20-30 yrs. (Decid. teeth = 1 yr before (Decid. teeth = 1 yr before

shedding) shedding) Clinical crown < anatomic crown.Clinical crown < anatomic crown.

Anatomical crownClinical crown

Coronal end )E(

Apical end )C.E.J.(

1 year before shedding in deciduous teeth and in perm. till

20-30 years.

First stage

Second StageSecond Stage The The bottombottom of g. sulcus is still on of g. sulcus is still on

the the EE. and the . and the apical end apical end of of attach. E. has shifted to the attach. E. has shifted to the cementumcementum. .

Persists to the age of 40 years or Persists to the age of 40 years or later. later.

Clinical crown < anatomic crown. Clinical crown < anatomic crown.

Second stage

Anatomical crown

Clinical crown

Coronal end )E(

Apical end )C(.

Persist till 40 years

Third Stage Third Stage The The bottombottom of g. suclus is at of g. suclus is at CEJCEJ and the and the attach. epith. is entirly on the attach. epith. is entirly on the cementumcementum. . It is a transitional stage. It is a transitional stage. Clinical crown = anatomic Clinical crown = anatomic crown. crown.

Third stage

Anatomical crownClinical crown

Coronal end )C.E.J.(

Apical end )C(

Transitory stage

Fourth Stage Fourth Stage The entire attach. Epith. is on The entire attach. Epith. is on

cementumcementum.. It represents recession of the It represents recession of the

gingiva. gingiva. Clinical crown > anatomic Clinical crown > anatomic

crown.crown.

Fourth stage

Anatomical crownClinical crown

Coronal end )C(

Apical end )C(`

Persists till the tooth is lost

Shift of DGJ First stage:

•In 1ry teeth: till one y. before shedding

•In permanent:till20-30 y.

Second stage:• persist to 40years.

Third stage:• transitory

Fourth stage:• gingival recession(pathologic)till loss.

Age Changes Age Changes 1. Clinically, the oral mucosa of 1. Clinically, the oral mucosa of

an elderly person has a an elderly person has a smoother and dryer surface smoother and dryer surface (atrophic and friable).(atrophic and friable).

2. 2. Histologically, the epith. Histologically, the epith. appears thinner with smooth appears thinner with smooth epith. - C.T. interface due to epith. - C.T. interface due to flattening of epith. ridges.flattening of epith. ridges.

3. The tongue shows a reduction 3. The tongue shows a reduction in no. of filiform papillae and a in no. of filiform papillae and a smooth or glossy appearance, smooth or glossy appearance, which may be exacerbated by which may be exacerbated by nutritional deficiency. nutritional deficiency.

The reduced no. of filiform The reduced no. of filiform papillae may make the papillae may make the fungiform papillae more fungiform papillae more prominent (patient may prominent (patient may consider it to be a disease consider it to be a disease stage). stage).

4. Aging is associated with 4. Aging is associated with decreased rates of:decreased rates of:

a)a) Metabolic activity.Metabolic activity.b)b) Epith. proliferation.Epith. proliferation.c)c) Tissue turnover.Tissue turnover.

5. Langerhan5. Langerhan’’s cells become s cells become fewer, which may contribute to fewer, which may contribute to a decline in cell mediated a decline in cell mediated immunity. immunity.

6. Appearance of nodular 6. Appearance of nodular varicose veins on the underside varicose veins on the underside of the tongue (caviar tongue).of the tongue (caviar tongue).

Tongue varicosities

7. In the lamina propria, a 7. In the lamina propria, a decreased cellularity occurs decreased cellularity occurs with an increased amount of with an increased amount of collagen. collagen.

8. Sebaceous glands (Fordyce8. Sebaceous glands (Fordyce’’s s spots) of the lips and cheeks spots) of the lips and cheeks also increase with age. also increase with age.

9. The minor salivary glands 9. The minor salivary glands show considerable atrophy with show considerable atrophy with fibrous replacement .fibrous replacement .

10. Postmenepausal women may 10. Postmenepausal women may have have

a)a) Dryness of the mouth. Dryness of the mouth. b)b) Burning sensation. Burning sensation. c)c) Abnormal taste. Abnormal taste.

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