486 junctional epithelium
TRANSCRIPT
![Page 1: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/1.jpg)
JUNCTIONAL EPITHELIUM
Nabin chaudharyBDS 2011
![Page 2: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/2.jpg)
Junctions in oral mucosa• Junctions in the oral mucosa are
lines or surfaces, where two
different types of mucosa meet each
other.
• Within the oral mucosa there are
three junctions:
• Mucocutaneous junction – the site
of transition between skin and
mucous membrane.
• Mucogingival junction – between
gingiva and alveolar mucosa
• Dentogingival junction – between
tooth and free gingiva
![Page 3: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/3.jpg)
Gingiva• Gingiva is that portion of the
oral mucosa that covers the tooth-bearing part of the alveolar bone and the cervical neck of the tooth
• Masticatory mucosa
• Morphologically gingiva is
divided into:
1. Attached gingiva
2. Free gingiva
3. The interdental papilla.
![Page 4: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/4.jpg)
Dentogingival junction
• Defined as the oral epithelium that extends from the mucogingival junction to the gingival margin where crevicular/sulcular epithelium lines the sulcus
• Sulcular epithelium+junctional epithelium=dentogingival junction
• Gingival sulcus has a depth of 0.5-3mm(avg.1.8mm)
• Any depth greater than 3mm,considered pathologic,a sulcus this depth is known as a periodontal pocket
![Page 5: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/5.jpg)
Epithelial components of gingiva
• The gingival epithelium is
subdivided into 3 sections:
• the oral epithelium (OE),
• the sulcular epithelium (SE),
and
• the junctional epithelium
(JE).
![Page 6: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/6.jpg)
Junctional epithelium
• Junctional epithelium is the
stratified non-keratinizing
epithelium, that surrounds the
tooth like a collar with a cross-
section resembling a thin wedge.
• The epithelium of the gingiva
which gets attached to the tooth
is called junctional or
attatchment epithelium.
![Page 7: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/7.jpg)
• Forms the floor of sulcus and attaches gingiva to tooth surface
• The union between this epithelium and tooth is referred to as epithelial attachment. It is bounded CORONALLY by the free gingival groove and APICALLY by the mucogingival junction
• Resembles REE in its structure in that they have a basal layer and few layers of flattened cells
![Page 8: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/8.jpg)
Arrangement of cells in attachment epithelium
![Page 9: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/9.jpg)
Junctional epithelium is unique as it possess 2 basement membranes – the internal and external basal lamina
Enamel
Lamina propria
Internal Basal Lamina External Basal LaminaHemidesmosomes
![Page 10: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/10.jpg)
• The junctional epithelium has 2
basal laminas, one that faces the
tooth (internal basal lamina)
and one that faces the
connective tissue (external
basal lamina).
• The proliferative cell layer
responsible for most cell
divisions is located in contact
with the connective tissue, i.e.
next to the external basal
lamina.
![Page 11: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/11.jpg)
• Cells of JE immediately adjacent to tooth attach to tooth by hemidesmosomes & basal lamina i.e. Internal Basal lamina
• Combination is known as the epithelial attachment,adhesive forces betn this zone are molecular in nature and act across a distance smaller than 4onm(400Ang)
• On opposite surface – JE in contact with lamina propria of gingiva & attached by hemidesmosomes and basal lamina i.e. External Basal Lamina
• IBL differs from EBL in that they lack laminin,anchoring fibrils and type IV collagen
• Cells of JE are attached to eachother primarily by desmosomes,and also by tight and gap junctions
![Page 12: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/12.jpg)
Cont…
• Coronally: 15-30 layers thick. Apically: narrows to 3-4 layers thick
• Extends upto 2mm on the surface of the tooth
• Contains fewer tonofilaments and desmosomal junctions
• Cytokeratins present are CK5,CK14,CK19(simple epithelia has CK8,CK18)
![Page 13: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/13.jpg)
• Shows no sign of differentiation to form a keratinized surface epithelium
• highest turnover rate of 5-6 days
• Highly permeable and it has large intercellular spaces,so that neutrophils have an easy passage in and out of the epithelium
• Also permits the easy flow of crevicular(gingival) fluid
• The junctional epithelium is more permeable than the oral or sulcular epithelium.
![Page 14: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/14.jpg)
Significance of JE
• Has attachment role and protective role• Helps maintain integrity of tooth / periodontium structure.• Permeability allows GCF and defence cells to pass across to
protect underlying tissues from disease processes (periodonal disease)
• GCF contains g globulins and polymorphonucleocytes (PNMs) giving it immunological / phagocytic properties to combat disease processes
![Page 15: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/15.jpg)
• The lysosomes of the junctional epithelium may have a phagocytic function
• Langerhans cells migrate to sulcular and oral epithelium when infection or inflammation is present
• These defence rxns to the bacteria in the gingival sulcus constitute barriers against the invasion of bacteria and the penetration of toxins
![Page 16: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/16.jpg)
• A diagnosis of gingivitis implies that the actual level of the junctional epithelial attachment has not migrated apically, but is still on the enamel or on the cementoenamel junction
• A diagnosis of periodontitis implies that the junctional epithelium has migrated apically two, three, or more millimeters from its original level at the cementoenamel junction
![Page 17: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/17.jpg)
Development of junctional junnction
• Junctional epithelium is derived from Reduced Enamel Epithelium(REE)
• Ameloblast after formation of enamel matrix they leave a thin membrane on the surface of enamel PRIMARY ENAMEL CUTICLE.
• Ameloblasts cells becomes flat cuboid cells – REE• As tooth erupts and crown penetrates overlying oral
epithelium a fusion occurs between REE and oral epithelium so that epithelium continuity is never lost
![Page 18: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/18.jpg)
• Remnants of PEC after eruption– NASMYTH’S MEMBRANE.
• Tip of crown emerged, the REE termed as PRIMARY ATTCHEMENT EPITHELIUM
• As Tooth erupts,REE grows shorter and forms gingival sulcus.
• The replacement of primary attachment epithelium by cells derived from gingival epithelium is called secondary attachment epithelium
![Page 19: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/19.jpg)
![Page 20: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/20.jpg)
![Page 21: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/21.jpg)
![Page 22: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/22.jpg)
![Page 23: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/23.jpg)
Shift of dentogingival junction• Position of gingiva on the surface of the tooth changes with time
• active eruption refers to the bodily movement of the developing
tooth through the overlying jawbone and oral mucosa into the
oral cavity.
• Active eruption normally stops when the erupting tooth comes
in contact with its antagonist in the opposite jaw.
• Passive eruption refers to the uncovering of the anatomic
crown because of apical recession of the surrounding tissues,
rather than bodily movement.
![Page 24: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/24.jpg)
• Passive eruption has been
classified into 4 stages• stage 1: bottom of the
gingival sulcus remains on enamel & apical end of attachment epithelium at CEJ
• The junctional epithelium is located entirely over the enamel.
• Persists in primary teeth for 1 yr of age before shedding and in permanent teeth upto 20-30 yrs
![Page 25: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/25.jpg)
• stage 2: bottom of GS on the enamel & apical end of attachment epithelum is shifted to the surface of cementum
• The junctional epithelium is located in part over the enamel and in part over the cementum
• Apical migration of sulcus is the result of detachment of basal cells and reestablishmrent of their epithelial attachment at a more apical level
• Dissolution of fibre bundles that were anchored in cervical parts of cementum,caused by enzymes formed by epithelial cells,by plaque metabolites or immunologic rxns
• Persists upto 40 yrs or later
![Page 26: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/26.jpg)
• Stage 3: Bottom of the GS at
CEJ & epithelial attachment
entirely on the cementum
• The entire junctional
epithelium is located over
cementum, with its coronal
end at the cemento-enamel
junction
![Page 27: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/27.jpg)
• Stage 4: Recession of gingiva(The entire junctional epithelium is located apical to the cemento-enamel junction)
![Page 28: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/28.jpg)
• 1st and 2nd stages (passive eruption),anatomic crown is larger than clinical crown
• 3rd and 4th represent recession
• In 3rd stage,anatomic and clinical crowns are equal
• In 4th stage, clinical crown is larger than anatomic crown
![Page 29: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/29.jpg)
![Page 30: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/30.jpg)
Dynamics of migration of tissues of dentoepithelial junction
![Page 31: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/31.jpg)
Enamel Cuticle• When the ameloblasts are replaced by oral epithelium a secondary
cuticle is formed
• Amorphous material between JE and underlying hard tissue
• Not visible in demineralised sections
• Cuticle also seen between JE and underlying cementum
• Secondary Enamel cuticle and cemental cuticle=dental cuticle
![Page 32: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/32.jpg)
![Page 33: 486 junctional epithelium](https://reader036.vdocuments.mx/reader036/viewer/2022081422/55c82c34bb61ebc8138b45ca/html5/thumbnails/33.jpg)
THANK YOU