Gingiva Histology: Oral & Dental Science

• The lecture covers the histology of the gingiva in oral and dental science.
• Students should be able to identify/label the anatomic areas of gingival epithelium by the end of this session.
• Students should also be able to describe the anatomy/function of oral, sulcular, and junctional epithelium, and the function of gingival connective tissue.
• Other structures that are part of the gingiva include the periodontal ligament, cementum, and alveolar bone.
• The lecture content is linked to the histology of the periodontal ligament, alveolar bone, and cementum.
• The periodontium consists of the gingiva, cementum, periodontal ligament, and alveolar bone.

Gingival Anatomy

• The three areas of epithelium that make up the dento-gingival junction are: junctional epithelium, sulcular epithelium, and oral epithelium.
• Key features visible in an intraoral image include the alveolar mucosa, mucogingival junction, attached gingiva, free gingival groove, free gingiva, and interdental papillae.
• The gingival col is located between the peaks of the interdental papillae apical to the contact area.

Oral Epithelium

• This covers the outer surface of the free and attached gingiva.
• It extends from the crest of the gingival margin to the mucogingival junction.
• It is the only part of the periodontium visible to the unaided eye.
• It is a type of stratified squamous epithelium.
• Listed from deepest to most superficial, the layers are:
  • Basal cell layer consisting of cube-shaped cells.
  • Prickle cell layer consisting of spine-like cells with large intercellular spaces that attach to each other with desmosomes.
  • Granular cell layer consisting of flattened cells with intracellular keratin.
  • Keratinized cell layer (stratum corneum) consisting of flattened cells with extensive intracellular keratin.
• It joins with underlying connective tissue in a wavy pattern.

Sulcular Epithelium

• This epithelium faces the tooth surface without being in contact with it.
• It is thin and nonkeratinized.
• It does not have rete pegs.
• The fluid from the gingival connective tissue flows into the sulcus because it is semi-permeable; this fluid is known as gingival crevicular fluid (GCF).
• The sulcular joins with connective tissue at a smooth interface without epithelial ridges.

Junctional Epithelium

• This is a stratified squamous nonkeratinized epithelium that joins the gingiva to the tooth surface.
• Its length ranges from 0.71 - 1.35mm.
• Cell thickness is 15-30 cells coronally and 4-5 cells thick at the apical zone, with high cell turnover.
• The body seals the opening created by teeth penetrating the continuous sheet of epithelium by attaching epithelium.
• It is named junction meaning "connection".
• Internal Basal Lamina is a thin layer of extracellular matrix between epithelial cells and the tooth surface.
• External Basal Lamina is a thin layer of extracellular matrix between epithelial cells and gingival connective tissue.
• Attachment to tooth surface is by hemidesmosomes and the internal basal lamina.
• There are 8-10 hemidesmosomes per micron at the coronal end and 2 per micron at the apical end.
• Attachment to connective tissue is by hemidesmosomes and the external basal lamina.

Cell Junctions

• Desmosomes connect neighboring epithelial cells and their cytoskeletons together.
• Hemidesmosomes connect epithelial cells to the basal lamina.
• Junctional epithelium functions to provide attachment, act as a barrier, and provide host defense.

Gingival Connective Tissue

• The gingival connective tissue of the free and attached gingiva provides solidity to the gingiva.
• It attaches the gingiva to the cementum of the root and the alveolar bone; it is also known as the lamina propria.
• It provides integrity and strength to gingival tissues via a dense network.
• Functions to transport water, nutrients, metabolites, and oxygen to and from individual connective tissue cells.
• It initiates a host-immune response.

Supragingival Fibers

• Alveologingival (AG) fibers extend from the alveolar crest to the gingival connective tissue.
• Circular (C) fibers ring around coronally above crestal bone.
• Dentogingival (DG) fibers fan into gingival connective tissue from the cementum.
• Periosteogingival (PG) fibers fan from the periosteum.
• Intergingival (IG) fibers run in a mesiodistal direction along the whole dental arch linking teeth together.
• Intercircular (IC) fibers encircle several teeth linking them together.
• Interpapillary (IP) fibers are located in the papilla to connect the oral and vestibular papilla.
• Transgingival (TG) fibers run from cementum to CEJ and run horizontally linking teeth together.
• Transeptal (TS) fibers run from cementum of one tooth to another over the crestal bone.
• The gingival sulcus in health is 0.69mm in depth.