Gingival Tissue and Junctional Epithelium Quiz

Clinical Correlations of Periodontal Anatomy

• The presentation is about the clinical and microscopic features of the periodontium.
• The periodontium is a combination of structures supporting the teeth.
• The presentation covers oral mucosa, gingiva, periodontal ligament, cementum, and alveolar process.
• The oral mucosa is composed of masticatory, specialized, and lining mucosa.
• Gingiva is part of the oral mucosa that forms a collar around the tooth neck.

Anatomical Areas of Gingiva

• Gingiva has specific anatomical parts:
  • Marginal gingiva (free or unattached gingiva)
  • Attached gingiva
  • Interdental gingiva
  • Mucogingival junction
  • Alveolar mucosa
• Marginal gingiva is the part of gingiva closest to the tooth.
• Attached gingiva is the firmly bound part of gingiva.
• Interdental gingiva fills the spaces between teeth.
• Mucogingival junction is the junction between the gingiva and alveolar mucosa.
• Alveolar mucosa is the soft tissue covering the alveolar process.

Gingival Sulcus

• The gingival sulcus is a V-shaped crevice around a tooth.
• The average depth of the sulcus is 1 to 3 mm in healthy individuals.
• The depth of the gingival sulcus is measured by periodontal probing.

Attached Gingiva

• Attached gingiva is a firm and tightly bound tissue.
• The width of the attached gingiva varies by location in the mouth.

Interdental Gingiva

• Interdental gingiva fills the embrasure between adjacent teeth.
• The shape of interdental gingiva varies according to tooth contact.

Microscopic Features of Gingiva

• Gingiva consists of epithelial and connective tissue components
• Epithelial components include oral epithelium, sulcular epithelium, and junctional epithelium.
• Epithelial turnover rates vary.
• Keratinized vs non-keratinized gingiva.

Oral Epithelium

• The oral epithelium is a primary barrier.
• It's stratified squamous, keratinized, or parakeratinized.

Sulcular Epithelium

• The sulcular epithelium is thin, non-keratinized, and stratified squamous.
• It lacks rete pegs.
• Its semipermeable.

Junctional Epithelium

• The junctional epithelium is a collar-like band of epithelium.
• It's stratified squamous and non-keratinizing.
• Its length ranges from 0.25 to 1.25 mm.
• The width is widest coronally.

Keratinization

• Keratinization is a series of biochemical and morphological events in keratinocytes.
• The principle cell type in keratinization is keratinocytes (90%).

Non-keratinization

• Lining mucosa is non-keratinized.
• Lining mucosa is thicker than keratinized mucosa.
• Lining mucosa has larger cell size and intercellular bridges.

Lamina Propria

• The gingival connective tissue is composed of 2 layers:
  • Superficial papillary layer
  • Deep reticular layer
• The gingival connective tissue consists of cells, blood vessels, neural elements, fibers, and a ground substance.

Gingival Connective Tissue

• Mainly composed of dense collagen fibers; type I and type III are the most common types.
• The location and insertion determine the gingival fiber classification.

Function of Gingival Fibers

• Gingival fibers help brace the marginal gingiva and withstand chewing forces.
• Gingival fibers attach the free gingiva to the cementum and adjacent gingiva.
• Gingival fibers are grouped into gingivodental, circular, and transseptal fibers.
• The gingival fibers are diverse in nature.

Cellular elements of PDL

• The PDL contains diverse connective tissue cells (fibroblasts, cementoblasts, osteoblasts), undifferentiated mesenchymal cells (UMCs), epithelial rests of Malassez, immune system cells, and cells associated with neurovascular elements.

Ground Substance of PDL

• The PDL ground substance includes glycosaminoglycans (GAGs), proteoglycans, glycoproteins (fibronectin, laminin), and has high water content (70%).
• Calicified structures, like cementicles, are present in the PDL.

Functions of PDL

• The PDL carries out physical, formative, and nutritional functions.

Periodontal Ligament Clinical Considerations

• The periodontal ligament is radiolucent on X-rays.
• The thickness of PDL varies depending on teeth function (more in functional teeth).
• PDL cells are capable of modeling ligament and bone.
• Accidentally exfoliated teeth can be reimplanted.

Cementum

• Cementum is a calcified connective tissue of mesodermal origin covering the tooth root.
• Cementum begins at the CEJ and extends to the apex.
• Cementum provides a medium for tooth root attachment.

Structure of Cementum

• Cementum has two types: Acellular and Cellular cementum.

Cementum Characteristics

• Cementum is less hard than dentin.
• Cementum is lighter yellowish in color.
• Under some experimental conditions cementum has been shown to be permeable to a variety of materials.
• Mineral content includes calcium phosphate and fluoride.
• Organic content includes collagen, proteoglycans, etc.

Schroeders Classification

• Schroeders classification of cementum includes different types, such as Acellular afibrillar cementum, Acellular extrinsic fiber cementum, Cellular mixed stratified cementum, Cellular intrinsic fiber cementum, etc.

Acellular Cementum

• Acellular is unfortunate terminology as some areas of the tissue do not contain cells.
• Covers dentin from CEJ to apex.
• Very thin at CEJ. Thickens towards root apex.

Cellular Cementum

• Mostly presents at the apical third of root.
• Cells are cementocytes, similar to osteocytes.
• Cementocytes are in spaces called lacunae.

Cementoenamel Junction (CEJ)

• Cementum overlaps the CEJ, frequently.
• In 30% of cases, the cementum joins the CEJ sharply.
• 5-10% of cases have no CEJ.

Alveolar Process

• The alveolar process is the portion of maxilla and mandible that supports tooth sockets (alveoli).
• Forms when teeth erupt.
• Disappears after tooth loss.

Alveolar Process Composition

• An external plate of cortical bone formed by Haversian/compact bone lamellae is present.
• The inner socket wall is thin, compact bone called alveolar bone proper (lamina dura in radiographs).

Alveolar Process Histology

• Contains openings to link the PDL with cancellous bone.

Alveolar Bone Clinical Considerations

• Alveolar bone remodeling leads to displacements.
• Interruptions in lamina dura are significant.
• Following extraction, alveolar bone has a tendency for resorption.
• Implant placement decreases ridge resorption rate.
• Fenestrations may lead to gingival recession.

Color of Gingiva

• Produced by vascular supply, keratinization, and pigment containing cells.
• Varies among individuals and is correlated to pigmentation.
• Lighter in fair-complexioned people.

Size of Gingiva

• Corresponds to cellular and intercellular components and their vascularization.

Gingival Biotypes

• Ochsenbein and Miller discussed the importance of gingiva thickness in restorative treatment planning.
• Thick and flat gingiva (85%) and thin scalloped gingiva (15%).

Thick Gingival Biotype

• Rel. flat; Dense fibrotic soft tissue; Rel. large amount of attached gingiva; Thick underlying osseous form; Rel. resistant to acute trauma.

Thin Gingival Biotype

• Highly scalloped architecture; Delicate soft tissue; Minimal amount of attached gingiva; Thin underlying bone; Reacts to trauma with recession.

Gingival Zenith

• The most apical point of gingival scallop.
• Location depends on tooth type (central incisor, lateral incisor, cuspid, bicuspid).

Surface Texture

• Gingiva appears textured to the touch (like an orange peel).
• Attached gingiva, but not marginal gingiva, exhibits this texture, called stippling.

Stippling of Attached Gingiva

• Stippling is an orange peel-like appearance.
• Best viewed when gingiva is dry. Shows variation by sex, and age (fine or coarse).
• Restricted to attached gingiva and central portion of interdental papilla.

Passive Eruption

• Stages of passive eruption of tooth through the gingival epithelium.

Connective Tissue Grafts

• Used when gingiva tissue is deficient.

Periodontal Probing

• Does not accurately measure sulcus/pocket depth.
• It overestimates depth due to penetration into inflamed tissues.

Gingival Crevicular Fluid

• Fluid in the gingival sulcus contains inflammatory exudate.
• Part of the inflammatory process
• Contains serum derived elements like proteins, immune cells, electrolytes.
• Plays a role in cleansing and antibacterial defense.

Interdental Col

• Not a powerful barrier to bacteria due to non-keratinized epithelium.
• The interdental col is a site of disease initiation.

Summary

• Summary of Key terms related to gingiva and adjacent tissues.
• Includes key parts like junctional epithelium, PDL, CEJ, etc with important specifications.

Homework

• An assignment to draw the periodontium.

References

• Chapter 3 (pages 19-49) from Newman & Carranza's Clinical Periodontology.

Test your knowledge on the characteristics and functions of gingival tissues, including junctional epithelium and the components of gingival connective tissue. This quiz covers various aspects such as cell types, collagen fibers, and the roles of gingival fibers. Perfect for dental students and professionals alike!