Microscopic Anatomy of the Gingival Epithelium and Periodontal Tissues

The oral epithelium is a stratified squamous epithelium protected by keratin, a tough fibrous structural protein.
It consists of four cell layers from deepest to superficial: - Basal cell layer (stratum basal): Cube-shaped cells. - Prickle cell layer (stratum spinosum): Spine-like cells with large intercellular spaces; cells attach via desmosomes. - Granular cell layer (stratum granulosum): Flattened cells with increased intracellular keratin. - Keratinized cell layer: Flattened cells with extensive intracellular keratin.
Interface: Tightly interdigitates with the underlying gingival connective tissue.

Thin, non-keratinized epithelial lining of the gingival sulcus.
Cellular Layers: - Basal cell layer - Prickle cell layer - Superficial cell layer (flattened cells without keratin).
Permeability: Highly permeable to gingival crevicular fluid ( $GCF$ ); flow is slight in health but increases in disease.
Interface: Smooth, flush interface with connective tissue in health.

Specialized epithelium forming the base of the sulcus and joining the gingiva to the tooth.
Location: Attached slightly coronal to the cementoenamel junction ( $CEJ$ ) in health.
Structure: Thin, non-keratinized tissue consisting of only two layers: - Basal cell layer - Prickle cell layer
Dimensions: - Length: $0.71 ext{ to } 1.35\,mm$ - Coronal thickness: $15 ext{ to } 30 ext{ cells}$ - Apical thickness: $4 ext{ to } 5 ext{ cells}$
Attachment Mechanisms: - To tooth: Via unidesmisomes and the internal basal lamina. - Adhesion Density: $4 ext{ to } 8 ext{ hemidesmisomes per micron (coronal)}$ $2 ext{ hemidesmomes per micron (apical)}$ - To connective tissue: Via hemidesmisomes and the external basal magma.
Functions: Provides a seal at the base of the sulcus, acts as a protective barrier, and signals immune responses for host defense.

Functions: Provides solidity and attaches gingiva to cementum and alveolar bone.
Cellular Component: $5\%$ - Includes fibroblasts, mast cells, and immune cells (macrophages, neutrophils, lymphocytes).
Extracellular Matrix ( $ECM$ ): - Protein fibers (primarily collagen): $55\% ext{ to } 65\%$ - Gel-like ground substance: $30\% ext{ to } 35\%$

Part of the dento gingival unit ( $JE$ + fibers) that reinforces attachment and resists masticore forces.
Fiber Groups: - Alveol gingival: Attaches gingiva to the bone periosteum. - Circular: Ring-like manner around the tooth. - Dento gingival: Embedded in cementum near $CEJ$ . - Periosteo gingival: Extends laterally from the bone periosteum. - Inter gingival: Links adjacent teeth around the last mallards. - Intercircular: Encircled several teeth. - Intercapillary: Located in the papilla. - Transrenovial: Extends between adjacent teeth. - Transseptal fibers: Passes from cementum of one tooth over the alley of the olegon to the adjacent tooth.

Thin sheet of fibrous tissue surrounding tooth roots.
Thickness: $0.05 ext{ to } 0.25\,mm$
Components: Fibroblasts, cementoblasts, osteoblasts, and remnants of Herpitt's epithelial root sheath.
Primary Functions: Support (anchoring the tooth), Sensory (tactile pressure and pain), Nutritive (blood supply), Formative (cementum/bone maintenance), and Resorption (via osteoclasts).

Alveolar crest group: Resists horizontal movement and extrusion.
Horizontal group: Resists horizontal pressure.
Oblique group: Resists vertical pressure (driving root into socket).
Apical group: Secures tooth against lifting forces.
Intra recticular group: Found in furcations of multirooted teeth for stabilization.
Sharpest fibers: The calcified terminal ends of PDL fibers embedded in the cementum and alveolar bone.