Epithelial Attachment Gingivo-Dental Junction PDF

# Introduction The epithelial attachment or gingivo-dental junction is the union between the epithelial cells on one hand and the dental surface on the other hand, it creates a physical and physiological barrier whose cohesion guarantees the integrity of the underlying periodontal structures # Def...

# Introduction The epithelial attachment or gingivo-dental junction is the union between the epithelial cells on one hand and the dental surface on the other hand, it creates a physical and physiological barrier whose cohesion guarantees the integrity of the underlying periodontal structures # Definition of the epithelial attachment The junctional epithelium provides an epithelial attachment that joins the gingiva to the calcified dental surface. The epithelial attachment is therefore the union between the epithelial cells on one hand and the dental surface on the other hand. The epithelial attachment is the product and a component of the junctional epithelium. It is made up of the internal basal membrane, hemidesmosomes and an organic product. # 2. Histological structure The epithelial attachment includes all the junctional structures between the gingiva and the tooth. From the tooth towards the connective tissue we distinguish: - Dental cuticle - Internal basal membrane - Hemidesmosomes - Junctional epithelium - External basal membrane - Acellular cement - Linear border ## 2.1. The dental cuticle Consisting of proteins, glycoproteins and polysaccharides, it appears as a thin layer interposed between the enamel surface and the ameloblasts. It is secreted by the ameloblasts during the transformation into squamous cells, later this layer becomes thicker and densifies, becoming homogeneous with a more or less regular contour, it never mineralizes. ## 2.2. The internal basal membrane Between the enamel and junctional epithelium, there is a 60 to 150 nm thick basal membrane, without a dense layer or lucida layer, clearly differentiated and composed of collagen type VIII, laminin, sulfated proteoglycans and glycoaminases, it is different from other basal membranes because it does not contain collagen type IV.  ## 2.3. Hemidesmosomes The cell-epithelial junctions are reinforced by structures called hemidesmosomes present on the cell membrane. They are closer to each other along the dental surface than along the epithelial junction-connective tissue. ## 2.4. Junctional epithelium It is also attached to the tooth by a sticky extra-membranous coating produced by the epithelial cells, and composed of proline and/or hydroxyproline and neutral mucopolysaccharides. ## 2.5. Linear border Fine electron dense, inconstant structure at the coronal level on the surface of the enamel or the cementum fibrillary interposed between the tooth and the internal basal membrane. - Thickness of 12 -20 µm - Condensation of protein elements (gingival fluid) - Absent at the level of the cementum fibrillary ## 2.6. Acellular afibrillar cement It appears as spurs or mineralized islands (2µm in diameter) adhering to the cervical enamel surface in a 2mm band. It is an acellular and afibrillar cementum that forms a successive lamination, more or less parallel, to the tooth surface.  # 3. Position of the epithelial attachment The epithelium is attached at a height and a level that depend on the tooth eruption stage, and differ according to the involved dental surface. The epithelial attachment is not static, it is located at different levels throughout life. - **First stage**: When the tooth is in place on the arch and reaches the occlusal level, the epithelial attachment and the base of the gingivo-dental sulcus are located on the enamel. - **Second stage**: Around 20 years the epithelial attachment proliferates, so that one part is located on the cement, and the other part is still on the enamel. The base of the sulcus remains on the enamel. - **Third stage**: The entire epithelial attachment is located on the cement, and the base of the sulcus reaches the amelo-cemental junction. As the epithelial attachment moves from the crown to the root [5], it appears in the same way, on the enamel, the cement or the dentine. - **Fourth stage**: The epithelial attachment moves on the cement. The base of the sulcus is located on the cement, but a part is bare. # 4.4. Defensive potential of the epithelial attachment ## 4.4.1. Permeability - Passage of ions + metabolites from the connective tissue towards the sulcular space - Passage of defense cells towards the S.G.D. ## 4.4.2. Phagocytosis PMN (important lysosomal activity) pass from the chorion towards the S.G.D. to phagocytize the desquamated cells. ## 4.4.3. Tightness and adhesiveness Cohesion between the different elements (A.E) allows protection of the deep periodontium. ## 4.4.4. Regeneration It takes place from the junctional cells or the cells of the sulcular epithelium after partial destruction or complete excision of the A.E. # Conclusion The epithelial attachment is a very small functional unit, but it plays a crucial role in preserving the integrity of the deep periodontium tissues.