Session 1: Structures of the Periodontium: Gingiva

Question 1

The periodontium is composed of which four structures

Answer 1

1) Gingiva
2) Cementum
3) Periodontal ligaments
4) Alveolar bone

Question 2

The functions of gingival epithelium include

Answer 2

• covers outer surface of body
• Lines cavities such as mouth
• Skin and oral cavity covering (mucosa) is composed of stratified squamous epithelial cells
  mechanical barrier against bacterial invasion and a part of the innate immune response to infectious inflammation in periodontal tissue

Question 3

The two types of epithelial cell junctions are

Answer 3

Attachment of epithelial cells provide strength to withstand mechanical forces and forms a protective barrier.

1) Desmosomes:
- Connects two neighbouring epithelial cells together. Cell-to-Cell. Maintains mechanical integrity of tissues
2) Hemidesmosomes:
- Adhesion between epithelial cells to the basal lamina

Question 4

Describe the structure and function of junctional epithelium

Answer 4

Forms the base of the sulcus and joins the gingiva to the tooth surface by hemidesmosomes.
Gingiva has ability to repair itself
Functions:
– Attaches gingiva to enamel and/or cementum of tooth
– Forms seal at base of gingival sulcus or pocket
– Serves as a protective barrier between plaque (biofilm) and connective tissue of the periodontium

Question 5

Describe the interface between the oral epithelium and connective tissue

Answer 5

Appear as ridges, known as ‘rete pegs’ extend from connective tissue into epithelial layer
- Covers the outer surface of the free gingiva and attached gingiva
- Stratified squamous Epithelium (multi-layered, more durable, highly organised, avascular).
Characteristics
• Increases surface area between the two tissues
• Increases strength between the two tissues
• Decreases distance between the blood supply (in connective tissue) and the epithelium
- Blood supply carried through connective tissue ‘papilla’
- Rete pegs found in healthy attached gingiva giving stippled appearance

Question 6

Explain differences between keratinized and non-keratinized epithelial cells and name examples of each

Answer 6

Keratinized
Process in which cytoplasm of outermost epithelial cells is replaced by keratin making it stronger and waterproof. E.g. Masticatory mucosa (hard palate)
- Have no nuclei
- Form tough, resistant layers
Non-keratinized epithelial cells
- Have nuclei
- Act as cushion against mechanical forces
E.g. Junctional and sulcular epithelium, floor of mouth, vestibule, inside of cheeks, soft palate and lips

Question 7

Explain how blood is supplied to the oral epithelium

Answer 7

Epithelial tissues do not contain blood vessels. Nourishment obtained from underlying blood vessels in connective tissue

Question 8

Name the anatomical areas of the gingival epithelium and characteristics of each

Answer 8

3 Anatomical areas
• Oral epithelium - Covers the outer surface of the free gingiva and attached gingiva
• Sulcular epithelium - Epithelial lining of sulcus. Extends from crest of gingival margin
to the coronal edge of the JE. Forms shallow ‘pocket’ or ‘cuff’ around the tooth
• Junctional epithelium - Epithelium that forms the base of the sulcus and joins the gingiva to the tooth surface by hemidesmosomes

Question 9

Recall the gingival fibre groups, their location and function

Answer 9

– Circular: encircles the tooth like a ring
– Dentogingival: attaches gingiva to teeth
– Dentoperiosteal: attaches gingiva to bone
– Alveologingival: periosteum of alveolar crest into gingival connective tissue
– Transeptal: Cementum from one tooth, over the alveolar crest to cementum of the adjacent tooth

Question 10

Functions of gingival fibre groups

Answer 10

• Attaches JE to tooth
• Attaches free gingiva to cementum and bone
• Withstands frictional forces (holding free gingiva against the tooth)
• Controls positioning (connects adjacent teeth