The gingiva is the part of the oral mucosa that surrounds the teeth and alveolar bone, forming a protective seal. It is anatomically divided into distinct regions with specific structural characteristics:
Components of the Gingiva
The gingiva consists of the following main components:
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Free Gingiva (Marginal Gingiva): This is the unattached portion of the gingiva that surrounds the tooth in the region of the cementoenamel junction (CEJ). It's about 0.5-2mm wide.
- It forms the soft tissue wall of the gingival sulcus.
- The free gingival groove (not always present) separates the free gingiva from the attached gingiva.
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Attached Gingiva: This part of the gingiva is firmly bound to the underlying periosteum of the alveolar bone and the cementum by connective tissue fibers.
- It's wider in the maxilla than in the mandible.
- The width varies in different areas of the mouth and tends to increase with age.
- It appears stippled (orange peel-like appearance) in healthy individuals, due to the connective tissue projections.
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Interdental Gingiva (Gingival Papilla): This is the portion of the gingiva located in the space between adjacent teeth.
- Its shape is determined by the contact relationship between the teeth.
- It consists of two papillae (one facial and one lingual/palatal) connected by a col (a concave area that is not keratinized).
- If teeth are not in contact, the gingiva is saddle-shaped.
Microscopic Structure
Microscopically, the gingiva consists of epithelium and underlying connective tissue:
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Gingival Epithelium: This is a stratified squamous epithelium that can be keratinized, parakeratinized, or non-keratinized depending on the location. It is composed of:
- Oral Epithelium (OE): Covers the outer surface of the free and attached gingiva; generally keratinized or parakeratinized.
- Sulcular Epithelium (SE): Lines the gingival sulcus; non-keratinized.
- Junctional Epithelium (JE): Attaches the gingiva to the tooth; non-keratinized and permeable, allowing for the passage of fluids and cells. It attaches to the tooth via hemidesmosomes and the basal lamina.
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Gingival Connective Tissue (Lamina Propria): This layer is composed of collagen fibers, fibroblasts, blood vessels, nerves, and ground substance. Collagen fibers are arranged in distinct groups, providing support to the gingiva. Major fiber groups include:
- Gingivodental fibers: Extend from the cementum into the gingiva.
- Circular fibers: Encircle the tooth within the gingiva.
- Transseptal fibers: Extend between adjacent teeth.
Clinical Significance
The anatomical structure of the gingiva is critical for maintaining periodontal health. Its integrity protects the underlying tissues from bacterial invasion and mechanical trauma. Changes in the gingival structure, such as inflammation (gingivitis), can lead to periodontal disease and eventual tooth loss. Understanding its anatomy is crucial for dental professionals in diagnosing and treating periodontal conditions.
