Periodontium Structure and Function

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Questions and Answers

What is the primary function of cementum?

To provide sensation to the tooth

To attach the tooth to the periodontal ligament

To produce dentin

To seal the open dentinal tubules (correct)

What is the width range of the periodontal ligament?

0.5 to 1 mm

1 to 2 mm

0.15 to 0.38 mm (correct)

0.05 to 0.1 mm

What is the main component of alveolar bone?

Cementum

Dentin

Mineralized organic matrix

Specialized connective tissue (correct)

What is the function of the periodontal ligament?

To attach the tooth to the alveolar bone Signup and view all the answers

What is the function of acellular cementum?

To cover the root surface before tooth reaches occlusal plane Signup and view all the answers

What is the function of cellular cementum?

To form after the tooth reaches the occlusal plane Signup and view all the answers

What is the classification of cementum based on location?

Radicular and coronal cementum Signup and view all the answers

What is the attachment apparatus of the tooth?

Periodontal ligament, cementum, and alveolar bone Signup and view all the answers

What is the main function of the jaw bones?

To distribute and reabsorb forces generated by mastication and other tooth contact Signup and view all the answers

What is the alveolar process divisible into on an anatomic basis?

Separate areas on an anatomic basis Signup and view all the answers

What surrounds the root of the tooth and gives attachment to principal fibers of the periodontal ligament?

Alveolar bone proper Signup and view all the answers

What is the term for the isolated areas in which the root is denuded of bone and marginal bone is intact?

Fenestrations Signup and view all the answers

What is the term for the denuded areas that extend through the marginal bone?

Dehiscences Signup and view all the answers

What is the portion of the jaw located apically but unrelated to the teeth?

Basal bone Signup and view all the answers

What is the main function of the gingivae?

To protect the underlying tissues Signup and view all the answers

What is the gingival sulcus?

A shallow groove around the tooth Signup and view all the answers

What is the function of the gingival fibers?

All of the above Signup and view all the answers

What is the color of the gingivae in health?

Pink Signup and view all the answers

What is the part of the periodontium that supports the fibers of the periodontal ligament?

Cementum Signup and view all the answers

What is the location of the gingival margin in health?

A few millimeters coronal to the cementoenamel junction Signup and view all the answers

What is the anatomical division of the gingivae?

Marginal, attached, and interdental Signup and view all the answers

What is the characteristic of the gingival sulcus in a fully erupted tooth?

It is a shallow groove Signup and view all the answers

Study Notes

Periodontium

Consists of investing and supporting tissues of the tooth: gingivae, periodontal ligament, cementum, and alveolar bone
Divided into two parts: gingivae and attachment apparatus (periodontal ligament, cementum, and alveolar bone)

Gingivae

Part of oral mucosa that covers alveolar processes of jaws and surrounds necks of teeth
In health, gingivae are pink, firm, and have a knife-edge appearance, scalloped around teeth
May be pigmented in certain ethnic groups
Gingival margin is a few millimeters coronal to cement-enamel junction
Gingival sulcus (or crevice) is a shallow groove, 0.5-3 mm in depth around a fully erupted tooth
Gingival tissues are keratinized and appear paler pink than non-keratinized oral epithelium

Clinical Features

Normal gingivae cover alveolar bone and tooth root to a level just coronal to cement-enamel junction
Gingivae are divided anatomically into marginal, attached, and interdental areas

Gingival Fibers

Functions:
- Stabilize attached gingivae to alveolar process
- Stabilize attached gingivae to tooth
- Help maintain epithelial seal to tooth
- Provide stability to tooth
- Provide rigidity to withstand forces of mastication
- Help maintain marginal/free gingivae firmly against tooth and adjacent attached gingivae

Periodontal Ligament

Soft, specialized connective tissue situated between cementum covering root of tooth and bone forming socket wall
Width ranges from 0.15 to 0.38 mm
Constituents:
- Periodontal ligament fibers
- Cellular elements
- Ground substances (glycosaminoglycans and glycoproteins)

Cementum

Calcified, avascular, mesenchymal tissue forming the outer covering of anatomic root
Functions:
- Provides attachment to collagen fibers of periodontal ligament to root
- Covers root surface, sealing open dentinal tubules, preventing dentinal sensitivity
- Aids in maintaining teeth in functional occlusion
- Contributes to process of repair after damage to root surface
Classification:
- According to location: radicular and coronal cementum
- According to cells present: acellular and cellular cementum
- According to fibers present: not specified

Alveolar Bone

Portion of maxilla and mandible that forms and supports tooth sockets (alveoli)
Specialized connective tissue with mineralized organic matrix
Main function is to distribute and reabsorb forces generated by mastication and other tooth contact
Consists of:
- Alveolar bone proper: thin lamella of bone surrounding root of tooth and giving attachment to principal fibers of periodontal ligament
- Supporting alveolar bone: surrounds alveolar bone proper and gives support to socket
  - Cortical plates: compact bone forming outer and inner plates of alveolar bone
  - Spongy bone (trabecular or cancellous bone): fills area between plates and alveolar bone proper