- There are three junctions in the oral mucosa: the mucocutaneous junction between the mucosa and skin, the mucogingival junction between the alveolar mucosa and attached gingiva, and the dentogingival junction between the tooth and gingiva. - The mucocutaneous junction, also called the vermilion border, is the transitional zone between the lip skin and mucosa. It is characterized by long papillae, large blood vessels, and sensory nerve endings. - The mucogingival junction can be identified clinically by the mucogingival groove and change in color from pink alveolar mucosa to pale gingiva. Histologically

1. JUNCTIONS IN THE
ORAL MUCOSA
BYBY
DR. Fawzy DarweeshDR. Fawzy Darweesh
Assistant professor of Oral BiologyAssistant professor of Oral Biology
Faculty of DentistryFaculty of Dentistry
Mansoura UniversityMansoura University

2. • 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)

3. Mucocutaneous JunctionMucocutaneous Junction
 Is the transitional zone between the skin ofIs the transitional zone between the skin of
the lip and its mucous membrane.the lip and its mucous membrane.
 It is called theIt is called the red zonered zone oror vermilionvermilion
borderborder..

4. The LipThe Lip
Skin SideSkin Side
Vermilion zoneVermilion zone
Mucous Membrane sideMucous Membrane side
Vermilion border
MMSkin

5. The lipThe lip
 Made of skletal muscles (orbicular oris).Made of skletal muscles (orbicular oris).
 The skin is coved by a moderately thickThe skin is coved by a moderately thick
keratinized st. squ. epith. withkeratinized st. squ. epith. with thickthick
stratum corneum (epiderms).stratum corneum (epiderms).

6.  Dermis : composed of C.T. rich in elasticDermis : composed of C.T. rich in elastic
fibers and blood capillaries.fibers and blood capillaries.
 The papillae:The papillae: fewfew andand shortshort..
 ManyMany sebaceous glandssebaceous glands are found inare found in
connection withconnection with hair follicleshair follicles..
 Sweat glandsSweat glands occur between them.occur between them.

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

8.  The transitional zone is characterized by:The transitional zone is characterized by:
1. Numerous long papillae, reaching deep1. Numerous long papillae, reaching deep
into the epith.into the epith.
2. The papillae carrying large capillary loops.2. The papillae carrying large capillary loops.
3. The papillae are rich in sensory nerve3. The papillae are rich in sensory nerve
endings.endings.
4. Contains only occasional sebaceous glands4. Contains only occasional sebaceous glands
(requires moistening by the tongue).(requires moistening by the tongue).
5. No sweat glands or hair follicles.5. No sweat glands or hair follicles.

9.  This zone is covered withThis zone is covered with partiallypartially
keratinized st. squ. epith.keratinized st. squ. epith.

10. The LipThe Lip
Skin SideSkin Side
VermilionVermilion
zonezone
MucousMucous
MembraneMembrane
sideside
Sebaceous
glands
salivary
glands
epidermis
( stratum lucidum)
Few & short papillae
Sweat & sebaseous
Glands(pale yellow spots)
thick nonkeratinized
st. sq. epithelium
dense 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).

11. Skin SideSkin Side
epidermis
( stratum lucidum)
eleidin
Sweat & sebaseous
glands
Sweat glands
A- Hair follicles
B- Sebaceous glands
C- Sweat glands

12. The LipThe Lip
Skin SideSkin Side
epidermis
(stratum lucidum)
Eleidin
•Hair follicles
•Sweat glands
• Sebaseous glands
Hair papilla
Hair root

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

14. Keratinized epith. of the skin below the vermilion
zone of the lip

15. Mucous Membrane SideMucous Membrane Side
of 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(

16. Mucogingival JunctionMucogingival Junction
 Clinically: identified byClinically: identified by
1. The mucogingival groove.1. The mucogingival groove.
2. Change from bright pink (alveolar2. Change from bright pink (alveolar
mucosa) to pale pink (gingiva).mucosa) to pale pink (gingiva).

17. Mucoging.
junction
Attached
gingiva
Alveolar
mucosa

18. Histologically ;Histologically ;
 The attached gingiva is keratinized orThe attached gingiva is keratinized or
parakeratinized.parakeratinized.
 The lamina propria contains numerousThe lamina propria contains numerous
collagen bundles attaching the tissue tocollagen bundles attaching the tissue to
periosteum (stippling appearance).periosteum (stippling appearance).

19.  The alveolar mucosa has a thicker,The alveolar mucosa has a thicker,
nonkeratinized epith.nonkeratinized epith.
 Overlying a loose lamina propria withOverlying a loose lamina propria with
numerousnumerous elastic fiberselastic fibers extending into theextending into the
thick submucosathick submucosa..

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

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

22. Dentigingival JunctionDentigingival Junction
 Is that region where the oral mucosa of theIs that region where the oral mucosa of the
gingiva (epithelium) meets the surface ofgingiva (epithelium) meets the surface of
the tooth.the tooth.

23. Dento-gingivalDento-gingival
JunctionJunction
andand
Gingival SulcusGingival Sulcus

24.  This junction is the principal seal betweenThis junction is the principal seal between
the oral cavity and the underlying tissues.the oral cavity and the underlying tissues.
 It is derived from theIt is derived from the reduced E. epithreduced E. epith..

25. Histogenesis of
Dento-gingival Junction

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

27.  The junctional epith. isThe junctional epith. is nonkeratinizednonkeratinized..
 It consists of flattened cells aligned parallelIt consists of flattened cells aligned parallel
to the tooth surface (from 1-4 layersto the tooth surface (from 1-4 layers
apically to 15-30 layers coronally).apically to 15-30 layers coronally).

28. Gingival Sulcus & DentogingivalGingival Sulcus & Dentogingival
JunctionJunction

29.  The epithelium has a smooth C.T.The epithelium has a smooth C.T.
interface where a basal lamina hasinterface where a basal lamina has
assoicatedassoicated hemidesmosomeshemidesmosomes..
 Furthermore, a basal lamina andFurthermore, a basal lamina and
hemidesmosomes are found between thehemidesmosomes are found between the
junctional epithelial cells and the enameljunctional epithelial cells and the enamel
(or cementum).(or cementum).

30.  The cells of the junctional epithelium immediately adjacent toThe cells of the junctional epithelium immediately adjacent to
the tooth attach themselves to the enamel or cementum bythe tooth attach themselves to the enamel or cementum by
hemidesmosomes within the cellhemidesmosomes within the cell and aand a basal laminabasal lamina produced byproduced by
the epithelial cells.the epithelial cells.
Mode of Attachment of DGJ
“ Epithelial Attachment”

31.  The basal lamina in contact with the tooth isThe basal lamina in contact with the tooth is
termedtermed the internal basal lamina.the internal basal lamina.
 The other surface of the junctional epithelium inThe other surface of the junctional epithelium in
contact with the lamina propria is the normal basalcontact with the lamina propria is the normal basal
laminalamina and termedand termed the external basal lamina.the external basal lamina.
 So the junctional epithelium is therefore unique inSo the junctional epithelium is therefore unique in
havinghaving two basal laminaetwo basal laminae..
Int. B. L.
Ext. B. L.
E

33.  Inflammatory cells (neutrophils) areInflammatory cells (neutrophils) are
present in the C.T. supporting the epith. ofpresent in the C.T. supporting the epith. of
the dentogingival junction.the dentogingival junction.
 These cells continually migrate into theThese cells continually migrate into the
junctional epith.junctional epith.
 They pass between the epith. cells toThey pass between the epith. cells to
appear in the gingival sulcus and in oralappear in the gingival sulcus and in oral
fluid.fluid.

34. Shift of Dentogingival JunctionShift of Dentogingival Junction
 The position of the gingiva on the toothThe position of the gingiva on the tooth
surface changes during eruption and asurface changes during eruption and a
gradual exposure of the crown follows.gradual exposure of the crown follows.

35.  The actual movement of the tooth towardThe actual movement of the tooth toward
the occlusal plane is termedthe occlusal plane is termed activeactive
eruptioneruption..

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

37.  Passive eruption has four stages.Passive eruption has four stages.
 The first two may beThe first two may be physiologicphysiologic and theand the
last two may belast two may be pathologicpathologic..

38. First StageFirst Stage
 TheThe bottombottom of the g. sulcus remains inof the g. sulcus remains in EE..
and theand the apical endapical end of attach. E. stays atof 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 shedding)(Decid. teeth = 1 yr before shedding)
 Clinical crown < anatomic crown.Clinical crown < anatomic crown.

39. Anatomical crown
Clinical
crown
Coronal end (E(
Apical end (C.E.J.(
1year before shedding in deciduous
teeth and in perm. till 20-30 years.
First stage

40. Second StageSecond Stage
 TheThe bottombottom of g. sulcus is still on theof g. sulcus is still on the EE..
and theand the apical endapical end of attach. E. has shiftedof attach. E. has shifted
to theto the cementumcementum..
 Persists to the age of 40 years or later.Persists to the age of 40 years or later.
 Clinical crown < anatomic crown.Clinical crown < anatomic crown.

41. Second stage
Anatomical
crown
Clinical crown
Coronal end (E(
Apical end (C(.
Persist till 40 years

42. Third StageThird Stage
TheThe bottombottom of g. suclus is atof g. suclus is at CEJCEJ and theand the
attach. epith. isattach. epith. is
entirly on theentirly on the cementumcementum..
 It is a transitional stage.It is a transitional stage.
 Clinical crown = anatomic crown.Clinical crown = anatomic crown.

43. Third stage
Anatomical
crownClinical crown
Coronal end (C.E.J.(
Apical end (C(
Transitory stage

44. Fourth StageFourth Stage
 The entire attach. Epith. is onThe entire attach. Epith. is on cementumcementum..
 It represents recession of the gingiva.It represents recession of the gingiva.
 Clinical crown > anatomic crown.Clinical crown > anatomic crown.

45. Fourth stage
Anatomical
crownClinical crown
Coronal end (C(
Apical end (C(`
Persists till the tooth is lost

47. 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.

48. Age ChangesAge Changes
1. Clinically, the oral mucosa of an elderly1. Clinically, the oral mucosa of an elderly
person has a smoother and dryer surfaceperson has a smoother and dryer surface
(atrophic and friable).(atrophic and friable).

49. 2.2. Histologically, the epith. appears thinnerHistologically, the epith. appears thinner
with smooth epith. - C.T. interface due towith smooth epith. - C.T. interface due to
flattening of epith. ridges.flattening of epith. ridges.

50. 3. The tongue shows a reduction in no. of3. The tongue shows a reduction in no. of
filiform papillae and a smooth or glossyfiliform papillae and a smooth or glossy
appearance, which may be exacerbated byappearance, which may be exacerbated by
nutritional deficiency.nutritional deficiency.

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

52. 4. Aging is associated with decreased rates of:4. Aging is associated with decreased rates of:
a)a) Metabolic activity.Metabolic activity.
b)b) Epith. proliferation.Epith. proliferation.
c)c) Tissue turnover.Tissue turnover.

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

54. 6. Appearance of nodular varicose veins on6. Appearance of nodular varicose veins on
the underside of the tongue (caviarthe underside of the tongue (caviar
tongue).tongue).

55. Tongue varicosities

56. 7. In the lamina propria, a decreased7. In the lamina propria, a decreased
cellularity occurs with an increased amountcellularity occurs with an increased amount
of collagen.of collagen.

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

58. 9. The minor salivary glands show9. The minor salivary glands show
considerable atrophy with fibrousconsiderable atrophy with fibrous
replacement .replacement .

59. 10. Postmenepausal women may have10. Postmenepausal women may 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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