Periodontium and Oral Mucosa Overview

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Questions and Answers

What does the term 'periodontium' refer to?

The tissues surrounding and supporting the teeth (correct)

The nerves associated with the teeth

The inflammation of the gums

The outer layer of the tooth

Which of the following is NOT a component of the periodontium?

Root cementum

Dentin (correct)

Alveolar bone

Gingiva

What type of mucosa is associated with the gingiva and hard palate?

Specialized mucosa

Alveolar mucosa

Lining mucosa

Masticatory mucosa (correct)

The area referred to as the 'mucogingival junction' is best described as:

The boundary where attached gingiva ends and alveolar mucosa begins Signup and view all the answers

What characterizes the alveolar mucosa?

It is dark red and movable Signup and view all the answers

Periodontics is primarily concerned with:

The prevention and treatment of periodontal diseases Signup and view all the answers

Which component of the periodontium is responsible for the attachment of the tooth to the bone?

Periodontal ligament Signup and view all the answers

Which of the following describes lining mucosa properly?

It lines the majority of the oral cavity except for the gingiva and hard palate Signup and view all the answers

What is the primary support structure of the tooth within the dentoperiodontal unit?

Periodontal ligament Signup and view all the answers

Which part of the gingiva is described as being well adapted to the tooth surface but not attached to it?

Marginal gingiva Signup and view all the answers

The free gingival groove is a defining feature that separates what two parts of the gingiva?

Marginal and attached gingiva Signup and view all the answers

Under ideal conditions, what is the probing depth of a normal gingival sulcus?

0 mm Signup and view all the answers

Where does the attached gingiva extend apically to?

Mucogingival junction Signup and view all the answers

What type of mucosa covers the alveolar process of the jaws?

Masticatory mucosa Signup and view all the answers

In how many adults is the free gingival groove generally present?

30-40% Signup and view all the answers

What is the depth of the gingival sulcus in a histological section?

1.8 mm Signup and view all the answers

What is the main structural feature of the basal layer of oral epithelium?

It comprises cuboidal or cylindrical cells with division ability. Signup and view all the answers

Which layer begins the synthesis of keratin in oral epithelium?

Granular layer. Signup and view all the answers

How long does it take for a keratinocyte to reach the surface of the epithelium?

3-4 weeks. Signup and view all the answers

Which type of cell is primarily responsible for melanin production in oral epithelium?

Melanocyte. Signup and view all the answers

What is the primary role of Langerhans cells in the oral epithelium?

Defense mechanism through antigen processing. Signup and view all the answers

Which of the following describes the structure of a hemidesmosome?

Outer leaflets separated by granulated material. Signup and view all the answers

Which statement about keratinized cell layer is true?

It is the most superficial layer where keratinization occurs. Signup and view all the answers

What feature contributes to the stippled appearance of attached gingiva?

Alternating pattern of depression and protuberances. Signup and view all the answers

What is the normal color of healthy gingiva in most individuals?

Coral pink Signup and view all the answers

Which factor does NOT influence the normal color of gingiva?

Presence of dental plaque Signup and view all the answers

What change is typically observed in gingival contour during inflammation?

It becomes rounded and enlarged Signup and view all the answers

Which statement is true regarding the consistency of inflamed gingiva?

It can be soft and spongy or extremely firm Signup and view all the answers

What surface texture is characteristic of attached gingiva?

Stippled Signup and view all the answers

Why is the junctional epithelium more susceptible to tearing during probing compared to the oral epithelium?

It is thinner and lacks keratinization. Signup and view all the answers

What happens to stippling in the gingiva as individuals age?

It frequently begins to disappear Signup and view all the answers

What is the turnover rate of the junctional epithelium compared to that of the oral epithelium?

4-6 days for junctional epithelium, up to 40 days for oral epithelium. Signup and view all the answers

What is the role of fibroblasts in the connective tissue?

They synthesize collagen and elastic fibers. Signup and view all the answers

How does the size of gingiva relate to overall gum health?

Alteration in size is a common feature of gingival diseases Signup and view all the answers

Which feature indicates a healthy gingiva's consistency?

Resilient and firm Signup and view all the answers

Which layer of the connective tissue lies between the papillary layer and the underlying structures?

Deep reticular layer Signup and view all the answers

Which statement correctly describes the structure of the epithelium and connective tissue interface?

It features a continuous sheet formed by the basement membrane. Signup and view all the answers

What is a distinguishing feature of the junctional epithelium compared to the oral and sulcular epithelium?

It forms an attachment to the tooth surface. Signup and view all the answers

Which cells are primarily responsible for phagocytic action in the connective tissue?

Macrophages Signup and view all the answers

What component of the connective tissue regulates collagen degradation?

Fibroblasts Signup and view all the answers

Study Notes

Periodontium

The term “periodontium” comes from the Greek words “Peri” meaning around and “odont” meaning tooth.
Consists of:
- Alveolar bone
- Root cementum
- Periodontal ligament (Supporting tissues)
- Gingiva (investing tissue)
Periodontal diseases are conditions affecting the tissues surrounding the teeth.
Periodontal therapy is the treatment of periodontal diseases.
Periodontology is the branch of dentistry focused on the health and diseases of the periodontium.
Periodontics is the branch of dentistry focused on prevention and treatment of periodontal diseases.

Oral Mucosa

The oral mucosa is composed of three zones:
- Masticatory mucosa:
  - Covers the gingiva and hard palate
  - Extends from the free gingival margin to the mucogingival junction.
  - No mucogingival junction on the palatal side as both gingiva and alveolar mucosa are masticatory mucosa.
  - Firmly attached to the underlying bone and covered with keratinized epithelium to withstand chewing forces.
- Specialized mucosa:
  - Covers the dorsum of the tongue
- Lining mucosa:
  - Lines the remainder of the oral cavity
  - Found on lips, cheeks, floor of the mouth, inferior tongue, soft palate, and alveolar mucosa
  - Alveolar mucosa is located apical to the attached gingiva and extends into the vestibule; it is darker red and movable because of the lack of elastic fibers.

Biology of the Periodontal Tissues

The periodontium functionally supports the teeth and consists of gingiva, periodontal ligament (PDL), cementum, and alveolar process.
The tooth and periodontium collectively are called the dentoperiodontal unit.
The periodontal ligament is the main support of the tooth, connecting the cementum to the alveolar bone.

Gingiva - Macroscopic Features

Part of the oral mucosa that covers the alveolar process and surrounds the neck of the teeth.
Protects the surrounding tissues from the oral environment.
Anatomically divided into:
- Marginal gingiva (free or un-attached gingiva):
  - Terminal edge of the gingiva surrounding the tooth in a collar shape.
  - Not attached to the tooth, separated by the gingival sulcus.
  - Separated from the attached gingiva by the free gingival groove.
  - Free gingival groove is a shallow depression that roughly corresponds to the base of the gingival sulcus.
  - Free gingival groove is about 1mm wide and present in about 30-40% of adults.
- Gingival sulcus:
  - Space between the tooth and the free gingiva, extending apically to the junctional epithelium.
  - V-shaped and barely permits the entrance of a periodontal probe.
  - Under ideal conditions, it is about 0mm.
  - The probing depth of a normal gingival sulcus is 2-3mm.
  - Histologically, the depth is about 1.8mm.
- Attached gingiva:
  - Firm and resilient part of the gingiva, tightly bound to the tooth and alveolar bone by gingival fibers and junctional epithelium.
  - Demarcated coronally by the free gingival groove and apically by the mucogingival junction.
  - The mucogingival junction is the meeting point of the attached gingiva and alveolar mucosa.
  - The connective tissue papillae and epithelial rete pegs create a patterned appearance.
- Interdental gingiva:
  - Gingiva located between teeth

Oral Epithelium

Composed of the following cell layers:
- Basal layer (Stratum basale or stratum germinativum):
  - Cuboidal or cylindrical cells with the ability to divide.
  - Separated from connective tissue by a basement membrane.
- Spinous layer (Stratum spinosum):
  - Consists of large cells with short cytoplasmic processes (spines).
- Granular Layer (stratum granulosum):
  - Contains electron-dense keratohyalin bodies, likely involved in keratin synthesis.
- Keratinized cell layer (Stratum corneum):
  - Most superficial layer, where para and ortho-keratinization occur.
Types of cells in the oral epithelium:
- Keratinocytes:
  - Most abundant cell type, accounting for 90% of the cell population.
  - Responsible for producing keratin, contributing to the protective function.
  - Undergo continuous proliferation and differentiation.
  - Take about 3-4 weeks to reach the outer surface and desquamate.
- Melanocytes:
  - Produce melanin pigment.
  - Found in the basal layer.
- Langerhans cells:
  - Play a role in the immune defense of the oral epithelium.
  - Recognize and process antigens.
- Merkel cells:
  - Located in the deeper layers of the epithelium.
  - Have nerve endings and are considered tactile receptors.

Desmosomes

Structures joining epithelial cells together.
Composed of two hemidesmosomes separated by granulated material (GM).
Hemidesmosomes are composed of:
- Outer leaflets (OL) of cell membrane
- Inner leaflet (IL) of the cell membrane

Junctional Epithelium

Fewer desmosomes in the junctional epithelium than the oral epithelium, possibly explaining its susceptibility to tearing during probing and greater permeability.
No keratinization or rete pegs, making it thinner than the oral epithelium.
Turnover rate is very high (4-6 days) compared to oral epithelium (6-12 days or up to 40 days).
Forms the attachment of the gingiva to the tooth surface.

Epithelial Connective Tissue Interface

Basement membrane is a continuous sheet connecting the epithelium and connective tissue.
A fibrillar structure called basal lamina is part of the basement membrane.
Composed of:
- Lamina lucida (adjacent to the basal epithelial cell)
- Lamina densa (located beneath lamina lucida)
- Anchoring fibrils projecting into the connective tissue.

Gingival Connective Tissue (CT)

Lamina properia supports oral epithelium and is divided into two layers:
- Superficial papillary layer:
  - Papillary projections between epithelial rete pegs.
- Deep reticular layer:
  - Lies between the papillary layer and underlying structures.
Lamina properia consists of cells, fibers, blood vessels embedded in an amorphous ground substance.
Cells of the connective tissue:
- Fibroblasts:
  - Most abundant cells (65%).
  - Synthesize collagen, elastic fibers, and connective tissue matrix.
  - Regulate collagen degradation.
- Mast cells:
  - Produce components of the matrix.
  - Produce vasoactive substances that may control blood flow.
- Macrophages:
  - Phagocytic action, play a role in defense mechanisms.
- Inflammatory cells:
  - Different immunological functions.
  - Including polymorphonuclear leukocytes, lymphocytes, and plasma cells.

Nerve Supply of Gingiva

Derived from the terminal branches of the maxillary and mandibular branches of the trigeminal nerve.

Clinical Descriptive Criteria of Clinically Healthy Gingiva and Inflamed Gingiva

Color

Clinically healthy gingiva is typically coral pink, with variations depending on:
- Melanin content
- Epithelial thickness
- Degree of keratinization
- Vascularity of the connective tissue
Dark skinned individuals may have dark blue or brown gingiva.
Inflamed gingiva varies in color from red to bluish-red due to vasodilatation, which leads to bleeding.

Contour

Clinically healthy gingiva has knife-edged margins and a scalloped contour.
Inflamed gingiva has rounded and enlarged contours, due to vascular stagnation and increased collagen formation.

Consistency

Clinically healthy gingiva is firm and resilient, tightly bound to the underlying bone due to dense collagen.
Inflamed gingiva may be soft and spongy due to vascular stagnation and decreased collagen, or extremely firm due to excessive collagen formation (fibrosis), characteristic of chronic inflammation.

Surface Texture

Clinically healthy gingiva may be either stippled or smooth and shiny.
- Attached gingiva is stippled.
- Free gingiva is smooth.
Inflamed gingiva may have reduced or absent stippling, but this is not an indicator of health.
Stippling can disappear with age.

Size

Gingiva size corresponds with the bulk of cellular and intercellular elements and vascular supply.
Changes in size are common in gingival diseases.

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Description

This quiz covers key concepts related to the periodontium and oral mucosa, including their definitions, components, and significance in dentistry. Understand the branches of dentistry focused on periodontal health and the structures involved in mastication and oral health.