LEC 1: Oral Mucosa and Gingiva

Periodontium Components

Consists of the gingiva, periodontal ligament, cementum, and alveolar bone, which function together as a single unit.

Oral Mucosa

The lining of the oral cavity consisting of three zones: masticatory mucosa, specialized mucosa, and the oral mucous membrane. (Lining mucosa)

Masticatory Mucosa

The zone of the oral mucosa that includes the gingiva and the covering of the hard palate.

Gingiva

The part of the oral mucosa that covers the alveolar processes of the jaws and surrounds the necks of the teeth.

Specialized Mucosa

The zone of oral mucosa that covers the dorsum of the tongue.

Oral Mucous Membrane

The zone of oral mucosa that lines the remainder of the oral cavity not covered by masticatory or specialized mucosa.

Marginal Gingiva

The terminal edge or border of the gingiva that surrounds the teeth in collar-like fashion, also called unattached gingiva.

Free Gingival Groove

A shallow linear depression that demarcates the marginal gingiva from the adjacent attached gingiva in about $50 \%$ of cases.

Gingival Zenith

The most apical point of the marginal gingival scallop.

What is the dimension of gingival zenith?

In between 0.06 and 0.96 mm

The marginal gingiva is usually about _____ wide.

1 mm

it forms the soft-tissue wall of the gingival sulcus

marginal gingiva

Gingival Sulcus Wall

A soft-tissue wall formed by the marginal gingiva, which may be separated from the tooth surface with a periodontal probe.

Mucogingival Line

The demarcation line between the attached gingiva and the darker alveolar mucosa.

Anatomical Divisions of Gingiva

The three areas the gingiva is divided into: marginal, attached, and interdental.

Normal Adult Gingival Level

Covers the alveolar bone and tooth root to a level just coronal to the cementoenamel junction.

Extracellular Matrix Components

Substances within one periodontal compartment that can influence the cellular activities of adjacent structures.

Marginal Gingiva Width

This part of the gingiva is usually about $1\,mm$ wide.

Gingival Zenith Dimensions

Refers to the apicocoronal and mesiodistal dimensions which vary between $0.06$ and $0.96\,mm$.

Attached Gingiva

The portion of the gingiva that is adjacent to the marginal gingiva and separated from the alveolar mucosa by the mucogingival line.

Interdental Gingiva

One of the three anatomical areas of the gingiva, located between the teeth.

Unattached Gingiva

Another name for the marginal gingiva, which forms the soft-tissue wall of the gingival sulcus.

Barrier Function of Gingiva

The specific structure of different types of gingiva reflects its effectiveness as a barrier to the penetration of microbes and noxious agents.

What is the definition of the gingival sulcus?

The gingival sulcus is the shallow crevice or space around the tooth bounded by the surface of the tooth on one side and the epithelium lining the free margin of the gingiva on the other side.

What is the characteristic shape of the gingival sulcus?

It is V-shaped.

What is the depth of the gingival sulcus under absolutely normal or ideal conditions?

$0\,mm$ or close to $0\,mm$.

Under what experimental conditions can a sulcus depth of $0\,mm$ be produced?

In germ-free animals or after intense and prolonged plaque control.

What is the reported histologic depth of the sulcus in clinically healthy human gingiva?

$1.8\,mm$, with variations from $0$ to $6\,mm$.

Besides $1.8\,mm$, what are two other sulcus depths reported in histologic studies?

$1.5\,mm$ and $0.69\,mm$.

How is the clinical probing depth determined?

By the introduction of a metallic instrument (periodontal probe) and estimating the distance it penetrates.

According to the transcript, why is the histologic depth of a sulcus not necessarily equal to the probing depth?

The penetration of the probe depends on factors such as probe diameter, probing force, and level of inflammation.

What is the probing depth of a clinically normal gingival sulcus in humans?

$2$ to $3\,mm$.

How is the attached gingiva described in terms of its connection to underlying structures?

It is firm, resilient, and tightly bound to the underlying periosteum of alveolar bone.

What boundary demarcates the facial aspect of the attached gingiva from the alveolar mucosa?

The mucogingival junction.

How is the width of the attached gingiva defined?

It is the distance between the mucogingival junction and the projection on the external surface of the bottom of the gingival sulcus or the periodontal pocket.

How does the width of the keratinized gingiva differ from the width of the attached gingiva?

The width of the keratinized gingiva also includes the marginal gingiva.

In which region of the mouth is the width of the attached gingiva generally the greatest?

The incisor region.

What is the mean width of the attached gingiva in the maxillary incisor region?

$3.5$ to $4.5\,mm$.

What is the mean width of the attached gingiva in the mandibular incisor region?

$3.3$ to $3.9\,mm$.

What is the width of the attached gingiva in the maxillary first premolars?

$1.9\,mm$.

What is the width of the attached gingiva in the mandibular first premolars?

$1.8\,mm$.

Why is the mucogingival junction significant regarding changes in the width of the attached gingiva over time?

The mucogingival junction remains stationary throughout adult life, so changes in width are caused by modifications in the position of the coronal portion.

At what age does the width of the attached gingiva typically increase?

By the age of $4$ years.

Besides age, what specific tooth condition can increase the width of the attached gingiva?

Supraerupted teeth.

Where does the attached gingiva terminate on the lingual aspect of the mandible?

At the junction of the lingual alveolar mucosa, which is continuous with the mucous membrane of the floor of the mouth.

How does the palatal surface of the attached gingiva relate to the palatal mucosa?

It blends imperceptibly with the equally firm and resilient palatal mucosa.

What is the gingival embrasure?

The interproximal space beneath the area of tooth contact occupied by the interdental gingiva.

What are the two possible shapes for the interdental gingiva?

Pyramidal or a "col" shape.

What characterizes the "col" shape of interdental gingiva?

A valley-like depression that connects a facial and lingual papilla and conforms to the shape of the interproximal contact.

What three factors determine the shape of the gingiva in a given interdental space?

The presence or absence of a contact point, the distance between the contact point and the osseous crest, and the presence or absence of recession.

What type of epithelium covers the col?

Nonkeratinized stratified squamous epithelium.

What forming structures create the lateral borders and tips of the interdental papillae?

The marginal gingiva of the adjoining teeth.

What constitutes the intervening portion between the lateral borders of the interdental papillae?

Attached gingiva.

What is the appearance of the gingiva if a diastema is present?

The gingiva is firmly bound over the interdental bone to form a smooth, rounded surface without interdental papillae.

What are the two microscopic components of the gingiva?

Overlying stratified squamous epithelium and an underlying central core of connective tissue.

What is the primary cellular nature of gingival epithelium vs. connective tissue?

The epithelium is predominantly cellular, whereas the connective tissue is less cellular.

What are the primary components of the gingival connective tissue?

Collagen fibers and ground substance.

Historically, what were the two perceived functions of the epithelial compartment?

To provide a physical barrier to infection and the underlying gingival attachment.

What is the modern view of the role of epithelial cells in the gingiva?

They play an active role in innate host defense by responding to bacteria.

In Figure 3.4, what does the arrow indicate following an extraction?

The intervening col between the facial and palatal interdental papillae.

How do the facial and lingual surfaces of the interdental papillae typically shape toward the contact area?

They are tapered toward the interproximal contact area.

How are the mesial and distal surfaces of teeth described in relation to the interdental gingiva?

They are slightly concave.

Which specific study reported a histologic sulcus depth of $0.69\,mm$?

Study number 93.