oral mucosa 3

what are the types of mucosa?

1. masticatory mucosa (gingiva and hard palate)

2. lining mucosa (loosely and firmly attached)

3. specialized mucosa (anterior 2/3 of the tongue and posterior 1/3 of the tongue)

What is the gingiva?

it is the part of the oral mucosa that surrounds the teeth and covers part of the alveolar bone.

What separates the gingiva from the alveolar mucosa?

The mucogingival junction, also called the scalloped line.

Is there a distinct mucogingival junction on the palatal aspect?

No. There is no distinct mucogingival junction on the palate.

what is the color of normal, healthy gingiva?

pink

morphologically, how is the gingiva divided?

1. Free gingiva (gingival sulcus)

2. Attached gingiva

3. Interdental papilla

what is the free gingiva?

The portion of the gingiva extending from the gingival margin to the bottom of the gingival sulcus (or slightly below it). It surrounds the cervical portion of the tooth on the labial, buccal, and lingual surfaces.

What separates the free gingiva from the attached gingiva?

The free gingival groove.

How far is the free gingival groove from the gingival margin?

About 1–1.5 mm.

How does the free gingival groove appear histologically?

a shallow V-shaped notch.

What is the gingival sulcus?

A shallow groove between the tooth and the free gingiva, lined by non-keratinized epithelium.

Where is the bottom of the gingival sulcus located?

At the point where the junctional (attachment) epithelium separates from the tooth.

What is the normal depth of the gingival sulcus?

0–6 mm, with an average depth of about 1.8 mm.

Which immune cells are commonly found in the connective tissue beneath the gingival sulcus?

Lymphocytes and plasma cells.

Why are lymphocytes and plasma cells found beneath the gingival sulcus?

They provide immune defense against bacteria entering through the gingival sulcus

What is the attached gingiva?

The immovable portion of the gingiva firmly attached to the cementum and periosteum. it extends from the free gingival groove to the mucogingival junction.

What is stippling?

A dimpled (orange-peel) surface appearance of healthy attached gingiva.

what does absence of stippling indicate?

Gingival inflammation (gingivitis).

What is the function of attached gingiva?

To resist the mechanical forces of mastication by being firmly attached.

why does attached gingiva appear to be slightly depressed between adjacent teeth?

due to the corresponding depression on the alveolar process between eminence of the sockets

Why does attached gingiva have a stippled appearance?

because high connective tissue papillae elevate the epithelium, while rete pegs create shallow depressions.

What is the interdental papilla?

The portion of gingiva that fills the interproximal space below the contact area of adjacent teeth.

What happens to the interdental papilla if there is no contact area between adjacent teeth?

It becomes reduced or absent.

What is the shape of the interdental papilla on the facial side?

Tent-shaped.

What is the shape of the interdental papilla on the lingual side?

Wedge-shaped.

Which fibers are found deep within the interdental papilla?

Transseptal fibers of the periodontal ligament.

What is the "col" of the interdental papilla?

A depression between the facial and lingual papillae.

Why is the col non-keratinized?

Because it lies beneath the tooth contact area and receives little functional stimulation.

what is the histology of the gingiva?

surface epithelium, which is almost completely keratinized, and there 3 types of it:

1. orthokeratinized

2. parakeratinized

3. nonkeratinized

what is orthokeratinized epithelium?

about 15% of gingival epithelium, it is a keratinized layer contains tightly packed cells with no nuclei.

what is parakeratinized epithelium?

about 75% of gingival epithelium, it is a keratinized layer where superficial cells retain pyknotic nuclei or nuclear remnants.

what is non-keratinized epithelium?

about 10% of the gingival epithelium, it is present in the epithelium lining of the gingival sulcus and Col region

Where are gingival fibers located?

the lamina propria of the attached gingiva.

What are the four principal groups of gingival fibers?

• Dentogingival fibers (main group)

• Alveologingival fibers

• Dentoperiosteal fibers

• Circular fibers

What type of mucosa covers the hard palate?

Keratinized masticatory mucosa.

What is the color and attachment of hard palate mucosa?

Pink in color and firmly attached (immovable) to underlying structures.

How many zones are present in the hard palate?

four zones, which are:

1. palatine gingiva

2. median palatine raphe

3. anterolateral area (fatty zone)

4. posterolateral area (glandular zone)

Describe the gingival region of the hard palate.

• Adjacent to teeth.

• No mucogingival junction (MGJ).

What is the median palatine raphe?

• A midline structure extending posteriorly from the incisive papilla.

• Difficult to differentiate between raphe and submucosa

what is the antero-lateral area (fatty zone)?

located between the median palatine raphe and gingiva, it is composed of fat cells and crosses the lamina propria to cross the submucosa to attach to the periosteum by fibrous bands.

what is the postero-lateral area (glandular zone)?

located between the median palatine raphe and gingival, it contains pure mucous glands.

What is the function of the fatty and glandular zones?

They act as cushions.

how does connective tissue thickness compare in the hard palate/

it is thicker anteriorly more than posteriorly

what is the incisive papilla?

a pear-shaped structure surrounded by folding formed by dense CT and is covered by epithelium known as the rugae area

What is the rugae area?

Folds around the incisive papilla formed by dense connective tissue covered by epithelium.

Hard palate histology resembles which structure?

Gingiva

How does hard palate epithelium differ from gingiva?

Long and broad rete pegs.

does the hard palate contain submucosa?

yes, which contains fat cells anteriorly and mucous glands posteriorly

What is lining mucosa?

Mucosa present in areas not subjected to high forces; it is mobile and flexible.

What are the characteristics of lining mucosa?

• Thick non-keratinized epithelium.

• Thin lamina propria.

• Submucosa containing:

  • Loose connective tissue.

  • Blood vessels.

  • Nerves.

  • Minor salivary glands.

What happens to rete pegs and connective tissue papillae in lining mucosa?

They are short or may be absent, producing a smooth basement membrane.

Classification of lining mucosa depends on what?

Thickness of submucosa.

What characterizes firmly attached lining mucosa?

Thin submucosa and attachment to underlying muscle.

what are examples of firmly attached lining mucosa?

1. lips

2. cheek

3. ventral surface of the tongue

4. soft palate

What characterizes loosely attached lining mucosa?

Thick submucosa and loose attachment to underlying structures.

what are examples of loosely attached lining mucosa?

• Alveolar mucosa.

• Vestibule.

• Floor of mouth.

what is the alveolar mucosa epithelium?

Stratified squamous non-keratinized epithelium with few or no epithelial ridges.

what is the alveolar mucosa lamina propria?

Loose connective tissue containing collagen and elastic fibers.

What does alveolar mucosa submucosa contain?

Thick elastic fibers and mixed salivary glands.

what is the vestibular fornix

very thin epith, lamina propria highly vascularized. allows mobility of lips and cheeks

Characteristics of floor of mouth mucosa?

• Very thin epithelium.

• Highly vascular lamina propria.

• loosely attached to underlying structures

• allows mobility of the tongue

what is the specialized mucosa?

it is found on the dorsal surface of tongue and is divided by V-shaped sulcus terminalis into two parts of the tongue:

• anterior 2/3 (papillary)

• posterior 1/3 (lymphatic / pharyngeal part)

What structures are present in anterior 2/3 of tongue?

• papillae

• taste buds

What structures are present in posterior 1/3 of tongue?

• lingual tonsil

what are the four types of tongue papillae?

1. filiform

2. fungiform

3. circumvallate

4. foliate

what is the site of filiform papillae?

parallel rows on dorsal surface of tongue

what is the shape of filiform papillae?

high, narrow and conical

what is the histology of filiform papillae?

central CT core covered by keratinized epithelium

do filiform papillae contain taste bud function?

no they have a mechanical function

what is the site of fungiform papillae?

between filiform papillae. they are numerous at the tip of the tongue

what is the shape of fungiform papillae?

mushroom shaped

what is the histology of fungiform papillae?

CT core covered by non keratinized epithelium

why are fungiform papillae red?

due vascular CT and thin nonkeratinized epithelium

how many taste buds are present in fungiform papillae?

1-2 taste buds

what is the taste sensation of fungiform papillae?

• tip of the tongue is for sweet sensation

• lateral borders of tongue is for salt sensation

what is the site of circumvallate papillae?

anterior to sulcus terminalis

what is the shape of circumvallate papillae?

narrow base with wide surface surrounded by deep trough

what is the histology of circumvallate papillae?

CT core covered by nonkeratinized epithelium

where are the Von Ebner glands located?

in circumvallate papillae in Ct at the base of the trough

where are taste buds located in circumvallate papillae?

In the walls of the trough.

what is the function of circumvallate papillae?

bitter taste sensation

what is the site of foliate papillae?

lateral borders of the tongue

what is the shape of foliate papillae?

parallel clefts

What glands are associated with foliate papillae?

von ebner glands

what is the function of foliate papillae?

sour taste sensation

where are taste buds found?

1. soft palate (bitter)

2. epiglottis

3. pharynx

4. tongue

what is the taste sensation of tongue papillae that have taste buds?

1. fungiform is sweet and salty

2. circumvallate is bitter

3. foliate is sour

Which nerve carries sweet and salty sensations?

Chorda tympani nerve.

Which nerve carries bitter and sour sensations?

Glossopharyngeal

What is the shape of taste buds?

Ovoid with rounded base toward connective tissue and pointed end toward surface.

What is the opening of taste bud called?

Taste pore.

What are the three types of taste bud cells?

• Supporting cells (Type I).

• Neuroepithelial/sensory cells (Type II).

• Basal cells (Type III).

Type I taste bud cells.

Supporting cells arranged like onion layers. outer is in contact with epithelial cells. also known as outer and inner supporting cells (sustentacullar)

Type II taste bud cells.

Neuroepithelial receptor cells responsible for taste stimuli. 10-12 cells present between the inner supporting cells

Type III taste bud cells.

Basal regenerative cells.

What structure is present in posterior 1/3 of tongue?

Lingual tonsil.

What forms lingual tonsil?

Aggregation of lymphatic nodules called lingual follicles.

Histology of lingual tonsil epithelium?

Non-keratinized epithelium extending downward to form crypts.

What fills the spaces between lymphatic centers?

Lymphocytes and plasma cells.

Which glands open into lingual crypts?

Weber mucous salivary glands.