Gingiva is the part of the oral mucosa that covers a part of alveolar process of jaw and surrounds the necks of the teeth.
Marginal Gingiva (Unattached Gingiva)
- Terminal edge of the gingiva surrounding the teeth in collar like fashion.
- Demarcated from attached gingiva by free Gingival groove
- 1 mm wide
- Marginal gingiva forms the soft tissue wall of gingival sulcus
- Attached gingiva is continuous with marginal gingiva
- Firm and resilient
- Firmly attached to the periosteum of alveolar bone
- It is extended into the alveolar mucosa facially
- Mucogingival juntion separates it from alveolar mucosa
- The width of attached gingiva – distance between Mucogingival junction and projection on the external surface of the bottom of the gingival sulcus or periodontal pocket
- The width on facial side:a.Incisor region–3.5 to 4.5 mm in maxilla–3.3 to 3.9 mm in mandibleb.Premolar region–1.9 mm in maxilla–1.8 mm in mandibleWith age and Supraerrupted teeth width of attached gingiva increases
- In mandible the termination of attached gingiva is at the juncture of lingual alveolar mucosa
- In maxila it is extended into the palatal mucosa
- This is gingiva seen in interproximal space just beneath the tooth contact area.
- It is of 2 types (a) pyramidal shaped, (b) col shaped
- In pyramidal type the papilla is beneath the contact point of two teeth.
- In col type there is a valley like depression connecting the facial papillae with the lingual papillae along the shape of the interproximal contact.
- Shape of the interdental gingiva is determined by contact point of teeth.
- The marginal gingiva from the adjacent teeth forms the lateral border and tip of the interdental gingiva.
- It is a shallow crevice which is bound by the tooth surface on one side and the epithelium lining the free gingiva on the other side.
- It is V shaped.
- In healthy and normal conditions the probing depth is 0.
- Normal depth is – 2 to 3 mm.
- The gingiva has centrally connective tissue which is covered by stratified squamous epithelium.
- Stratified squamous epithelium can be found in different areas of gingiva such as:
- Oral or outer epithelium
- Sulcular epithelium
- Junctional epithelium
- Principal cell present in gingival epithelium is keratinocytes.
- The other cells found are:
- Langerhan's cells
- Merkel cells
- Located in deeper layer of the epithelium.
- Contains nerve endings.
- Connected to adjacent cells through Desmosomes.
- They are tactile perceptors.
- They are dendritic cells.
- Located at the basal and spinopus layers of gingival epithelium.
- They form melanin in organelles called Premelanosomes or melanosomes.
- Contain enzyme tyrosinase.
- Melanophages or Melanophores phagocytose melanin granules which are present in the epithelium and connective tissue.
- Consists of collar like bands of stratified squamous non-keratinising epithelium.
- At 1st it is 2 to 3 layers thick in early life.
- In later stages it becomes of 10 to 20 layers thick.
- ➢ These cells are arranged in 2 stratas –(a) basal(b) suprabasal.
- Normal length of junctional epithelium is 0.25 to 1.35 mm.
- Keratin polypeptides present in junctional epithelium are - K19, K5 and K14.
- There is decreased glycolytic activity.
- Decreased phosphatase activity.
- Junctional epithelium is attached to tooth by internal basal lamina.
- It is attached to gingival connective tissue by external basal lamina
- ➢ Internal lamina has 2 parts—(a) lamina densa.(b) lamina lucida.
- Hemidesmosomes are attached to the lamina densa and lamina lucida
- From enamel the organic strands extend in to lamina densa.
- Juntional epithelium is attached to the afibrillar cementum present on crown and root cementum.
- The junctional epithelium cells help the production of laminin and hence adhesion occurs.
- The gingival fibers reinforces the junctional epithelium attachment. (Figure 1.3)
- The combination of junctional epithelium and gingival fibers is collectively called as dentogingival unit.
Gingival Connective Tissue
- Connective tissue of gingiva is known as lamina propria.
- Connective tissue has cellular and extracellular compartment (fibers and ground substance present)
- The space between cells and fibers is filled by ground substance.
- Ground substance consists of proteoglycans (hyaluronic acid and chondroitin sulfate) and glycoproteins (fibronectin).
- Fibronectin binds fibroblasts to the fibers
- ➢ Three types of connective tissue fibers –(a) collagen(b) reticular(c) plastic.
- Collagen type I is abundant
- Collagen type I gives tensile strength to the gingival tissues.
- Collagen type IV branches in-between the collagen type1 fibers.
- Type IV runs continuously along the fibers of the basement membrane and blood vessel walls.
- The marginal gingiva contains collagen fiber bundles called gingival fibers. (Figure 1.4)
- The fibers are type I collagen fibers.
- Functions of gingival fibers are:
- To hold the marginal gingiva firmly against the tooth.
- To give enough rigidity to tolerate the forces of mastication so that deflection from tooth surface does not occur.
- Attaches free marginal gigiva to the cementum of the root and adjacent attached gingiva.
- Gingival fibers are arranged in 3 groups:
- They are present in the facial, lingual and interproximal surfaces.
- Present within the cementum just beneath the gingival sulcus.
- It projects in a fan-like fashion from the cementum on facial and lingual side towards the crest and outer surface of marginal gingiva but terminates short of epithelium.
- They extend externally to the periosteum of facial and lingual alveolar bones and terminate in the attached gingiva or periosteum.
- Circular fibers pass through the connective tissue of marginal gingiva and interdental gingiva in a ring-like fashion.
- Present interproximally.
- They are horizontal bundles of fibers.
- Extends from cementum of one tooth to cementum of adjacent tooth.
- It is present between the epithelium at base of gingival sulcus and crest of interdental bone.
- The other gingival fibers found in gingiva are:
- Semicircular Fibers
- Present in the proximal surface of a tooth just below the CEJ.
- It extends facially or lingually and attaches itself to on the other side of the same tooth on the proximal surface.
- Transgingival fibers
- It is attached on the proximal surface of one tooth and moves diagonally in the interdental space, goes around the facial or lingual surface of the adjacent tooth and again moves diagonally in the interdental space and attaches in the proximal surface of the next tooth.
Cellular Elements in Gingiva
- Mast cells
- Fixed macrophages and histiocytes
- Adipose cells
- Small foci of plasma cells and lymphocytes
Blood Supply, Lymphatics and Nerves
- There are three sources of blood supply to gingiva. They are:
- Occurs on facial and lingual surface of alveolar bone.
- The capillaries from these extend along the sulcular epithelium and in-between the retepegs of external gingival surface.
Vessels of Periodontal Ligament
- These vessels extend in to the gingiva and anastamose with capillaries in sulcus area.
Arterioles from the Crest of Interdental Septa
- These vessels run parallel to the crest of the bone and anastamoses with vessels of the periodontal ligament, with capillaries in gingival crevicular areas and vessels that run over the alveolar crest.
- Beneath the epithelium on outer gingival surface, capillaries extend into the papillary connective tissue between the retepegs in the form of terminal hairpin loops.
- Brings lymphatics from the connective tissue papillae.
|Differences between gingival mucosa and alveolar mucosa|
Pink in color
Red in color
Smooth and shiny
Epithelium has retepegs
Epithelium has no retepegs
Connective tissue is tightly bound and less blood supply
Connective tissue loosely arranged and more blood supply
- Gingiva gets nerve supply from fibers arising from periodontal ligament and labial, buccal, and palatal nerves.
- The nerve structures present in gingival connective tissue are:
- Meshwork of terminal argyrophillic fibers.
- Encapsulated spindles.
- Meissner-type tactile corpuscles.
- Krause-type end bulbs.