Oral Mucosa

vermillion border ; pharyngeal mucosa

The lining of the oral cavity is continuous with the _____ of the lips to _____ in the region of soft palate and anterior pillars of fauces

Ectoderm (except tongue)

Origin of the oral mucosa

Orban and Sicher

Classified the oral mucosa into 3 types

Masticatory mucosa

Areas of free and attached gingiva and hard palate

• comes in primary contact with food during mastication

• keratinized

Lining mucosa

Areas of the lips, cheeks, vestibule, floor of the mouth, inferior surface of the tongue, soft palate

• little attrition

• soft, pliable, nonkeratinized

• adaptable, easily shaped

Specialized mucosa

Mucosa on the dorsum of the tongue

• Protection

  • against mechanical forces

  • normal resident population in the oral cavity

• Sensation

  • touch, pain, pressure, taste, gag and salivation reflexes

• Secretion

• Permeability and absorption

• Thermal regulation (for lower mammals)

Functions of the oral mucosa

Xerostomia

Dryness of mouth; blockage of salivary glands

• Orthokeratinized

• Parakeratinized

• Incomplete parakeratinized

• Nonkeratinized

Types of surface epithelium according to keratinization

Orthokeratinized

Type of Keratinized Epithelium

• Stratum corneum is homogenous and made up of flat, closely packed keratinized cells with no nuclei

• Found in: hard palate, attached gingiva, lingual papillae

Parakeratinized

Type of Keratinized Epithelium

• Presence of nuclei within the keratinized layer

• Flat, keratinized cells with pyknotic nuclei and remnants of cytoplasmic organelles

• Found in: dorsal surface of tongue (lingual papillae)

Incomplete parakeratinization

Type of Keratinized Epithelium

• Least common; seen only in marginal gingiva

• Outermost cells retain some nuclei and don't fully keratinize

• Some are keratinized, some are not

• Found in: marginal gingiva

Stratum superficiale

• Stratified squamous epithelium with nucleus

• Without keratin

• Cells appear slightly more flattened

Stratum intermedium

• Between stratum basale and stratum superficiale

• Larger polyhedral-shaped cells which migrated away from basal layer and lost ability to divide

• Forms the bulk of nonkeratinized epithelium

Stratum basale

• Cuboidal or columnar cells resting on a basement membrane

• Production of new epithelial cells

Papillary layer

• CT that indents the epithelium; short or absent in some mucosa

• epithelial ridges (rete pegs) interlock

• richly vascularized

• contains immune cells

Reticular layer

Consists of densely arranged connective tissue fibers, collagen fibers, some glands (reticular)

Marginal gingiva

• Part of free gingiva that tapers to a knife-like edge extending along the cervical level of the tooth on labial or buccal and lingual surfaces

• nagagalaw

Attached gingiva

• Stippling/orange peel appearance

• lighter color than alveolar mucosa

Inflammation / gingivitis

Loss of stippling may be caused by _____

Attached gingiva

Hard palate has the same color as _____

Alveolar mucosa

Soft palate has the same color as _____

Lingual

Which side is more painful when injected, lingual or buccal?

Marginal Periodontium (Gingiva)

• Covers the coronal part of the alveolar process

• Passes over the crest of the alveolar bone & interdental septa

• Encircles the necks of the teeth

Inflammation

Marginal gingiva is rolled; interdental gingiva is rounded

• Attachment of teeth and stabilization

• Unites teeth into a continuous dental arch

• Forms the epithelial cuff

• Defense against infection

Functions of gingiva

Free gingiva

• made up of a narrow band of tissue that follows the scalloped contour of the necks of the teeth and CEJ

• can be moved mechanically along the tooth surface & away from the tooth

• delicately attached to the tooth surface; can be torn and split clinically with negligible force

Free gingival groove

Separates the free gingiva from the attached gingiva

Gingival sulcus

A shallow groove between the tooth surface and free gingiva, extending around the circumference of the tooth

Col

The area of tissue in the interdental space that connects the facial and lingual free gingiva

Interdental folds

Slight depressions in between roots of teeth

Free gingival groove

Coronal boundary of attached gingiva

Mucogingival junction

Apical boundary of attached gingiva

Palatal side of maxilla

There is no attached gingiva in the _____

Deciduous dentition

Attached gingiva is narrower in _____

Maxillary lateral incisors

Attached gingiva is widest over the _____

Mandibular canine, 1st premolars (or deciduous 1st molars)

Attached gingiva is narrowest in _____

Anterior teeth

In the mandible, attached gingiva is narrower on the lingual surface of _____

Molars

In the mandible, attached gingiva is wide on the lingual surface of _____

Mucogingival junction

Separates attached gingiva from alveolar mucosa

Loss of contact area

Why is col not visible when teeth are extracted?

Dentinogingival junction

Interface between gingiva and the tooth surface

Reduced enamel epithelium (REE)

Embryonic origin of junctional epithelium

• Epithelial attachment

• Inner attachment epithelium

• Epithelial cuff

Other previously known terms for junctional epithelium

Junctional epithelium

• Binds gingiva to tooth surface

• Epithelial part of the free gingiva NOT visible from outside

• High turnover rate, contains a few leukocytes

• Junctional epithelium

• Oral sulcular epithelium

• Oral gingival epithelium

Dentinogingival junction consists of _____

Oral sulcular epithelium

• Lines the lateral wall of the gingival sulcus

• Continuous with occlusal end of junctional epithelium apically; with oral gingival epithelium occlusally

• Histologically — dark cells due to basophilic staining

• Stratified; frequently parakeratinized; no homogenous stratum corneum

• Less permeable than junctional epithelium, not infiltrated with migrating leukocytes

Oral gingival epithelium

• Covers the vestibular and lingual/palatal surfaces of the marginal and alveolar gingiva and the interdental gingival papillae

• Resembles epithelium of hard palate

Lamina propria

• Greatest portion of the free and attached gingiva

• 50-60% collagen fibrils

• fibroblasts

  • type I, II, V collagen

  • collagenase

  • ground substance

Biologic width

Attachment of gingiva to tooth from base of sulcus down to crest of the alveolar bone

Dentogingival fibers

• Most numerous fiber

• Consists of 3 groups:

  • Extends from cementum in an obliquely coronal direction

  • Streams horizontally from the cementum into free marginal gingiva

  • Run parallel with dentoperiosteal fibers

Dentoperiosteal fibers

• Insert into the supra-alveolar cementum at the same level as the transseptal fibers

• Pass apically over the crest of alveolar bone through vestibular and oral gingiva and into the periosteum of the cortical plates of alveolar process

Alveologingival fibers

• Insert into the crest of the alveolar bone

• Course coronally and enter the free and attached sections of the marginal and interdental gingiva

Circular fibers

• Small group of fibers that form a band around the neck of the tooth, interlacing with other groups of fibers in the free gingiva

• Helps bind free gingiva into the tooth

Semicircular fibers

Insert in the interdental cementum and encircle only the vestibular or oral half of the root

Transseptal fibers

• Cross the CT of the interdental gingiva (mesiodistally)

• Traverse the interdental septum as a strong membrane

• Bind the supra-alveolar cementum of one tooth to that of the adjacent tooth

• aka Interdental ligament

• Major cause of post retention relapse of orthodontically positioned teeth

• Capable of protein turnover and/or remodelling under normal physiologic conditions

Transgingival and intergingival fibers

• Reinforce the circular and semicircular fiber bundles

• Parts of it are identical with semicircular fibers

• Insert interdentally into supra-alveolar cementum

Interpapillary fibers

Cross through the free portion of interdental gingiva tissue in an orovestibular direction to tie the oral and vestibular gingival papillae together

Periosteogingival fibers

• Insert into the periosteum of the cortical plates of the alveolar process

• Pass facially and orally into the section of all attached gingiva lying over it

Intercircular fibers

• Located on the vestibular and oral sides of the interdental gingiva

• Connect the circular bundles of neighboring teeth

• Form part of the intergingival fiber bundles

Rete pegs / epithelial ridges

• Projections of the epithelium to the CT

• Interact with the dermal papillae

Interdental papilla

Gingival tissue in the interdental spaces, if proximal contact exists

Epithelial attachment

• Between junctional epithelium and tooth surface

• Product of junctional epithelium

• Maintains the bond between gingiva and tooth surface

Connective tissue attachment

Between the crest of the alveolar bone on interdental bony septum and the CEJ, fiber bundles of the gingival connective tissue insert into the supra-alveolar cementum