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Microscopic structure of the gingiva (Connective tissue (Fibers (Collagen…
Microscopic structure of the gingiva
Stratified Squamous epithelium
Oral Sulcular Epithelium (OSE)
non keratinized
thought to be due to sub-clinical inflamation
More permeable to water soluble substances than OGE
No keratohyalin granules in stratum granulosum
No dense cytoplasmic granules that promote dehydration + keratin cross linking
Contains lysosomal activity
From free gingival margin to the coronal end of the jnx epi.
Junctional epithelium
Features:
Extends from base of sulcus to CEJ
Has high turnover rate 4-6 days vs 6-12d for OGE, –> fast recovery
Forms a collar around cervical part of tooth
Wide and distensible intercellular spaces: 20 cell layers coronally from base of the sulcus to 1-2 cell layers near CEJ
Non-differentiated stratified epithelium
Serves as a pathway for a transudate and inflammatory exudate
Arises from the REE during tooth eruption
Expresses IL-8 to attract PMNs by chemotaxis
Highly permeable
Connected cells are attached by desmosomes
Has full basement membrane @ interface with CT, and basal lamina @ interface with tooth surface (no lamina reticularis)
Basal lamina contains laminin 5, that mediates cells adhesion
Basal lamina + hemidesmosomes form epithelial attachment (to the tooth)
Oral gingival epithelium (OGE)
Usually parakeratinized, but sometimes orthokeratinized
Divided into 4 layers:
Stratum spinosum (prickle cell layer)
Stratum granulosum (granular cell layer
Stratum basale/germinativum
Stratum corneum
no stratum lucidum as in skin
Cells:
Melanocytes
Langerhans cells (APCs)
Keratinocytes 90%
Merkel's cells (mechanoreceptors)
Features:
Forms a cornfield protective outer layer
Has many spinous cells to form numerous keratin fibrils and desmosomes that increases stability of epi
Develops a permeability barrier to water soluble subs.
Has retepegs that amplify the interface b/w basal cell and CT
Connective tissue
Fibers
Reticulin fibres at epithelium-CT and endothelium-CT interfaces
Oxytalan fibres: Scarce in gingiva, but numerous in PDL, funx unknown, thought to keep open bvs
Collagen fibers (predominant), appears in bundles
Principal fibres of CT of gingiva (there are 10)
Dentoperiosteal
From cementum near CEJ into periosteum of alveolar crest
Anchor tooth to bone, protect PDL
Circular
Within free marginal and attached gingiva, coronal to alveolar crest, "purse string"–>encircle each tooth
Maintain contour and position of free gingival margin
Alveologingival
From periosteum of alveolar crest coronally into lamina propria
Attach gingiva to bone
Transeptal
From inter proximal cementum to alveolar crest, course M + D in interdental area into cementum of adjacent tooth
Maintain rel. of adjacent teeth, protect interprox. bone
Dentogingival
From cementum laterally into lamina propria of gingiva
Provide gingival support
Elastic fibers, in gingiva and PDL only in assoc. with bvs
matrix
Proteoglycans
GAGs as carbohydrate unit (hyaluronan sulfate, heparan sulfate) attached to ≥1 protein chains via covalent bonds
Glycoproteins
Fibronectin (helps to connect cells to fibres), osteonectin etc.., predominantly protein
macromolecules are important for the resilience of the gingiva, in inflammation, macromolecules are destroyed resulting in edema
Cells
fibroblasts (5% CT or 65% of total cells in CT)
Produce fibers, mostly collagen which is 60% of matrix volume
Macrophages
Phagocytic
synthetic
Mast cells
Produce vasoactive substances, can affect the funx of the microvascular system
Plasma cells, neutrophils, lymphocytes
Vessels and nerves (35%)