The Normal Periodontium and Supporting Structures

VOCABULARY flashcards covering the components, clinical features, and histology of the normal periodontium, its supporting structures, and age-related changes.

Investing tissue

The part of the periodontium consisting of the gingiva.

Supporting tissues

The parts of the periodontium consisting of cementum, periodontal ligament, and alveolar bone.

Masticatory mucosa

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

Specialized mucosa

The type of oral mucosa specifically found on the dorsum of the tongue.

Lining mucosa

The oral mucous membrane lining of the oral cavity proper.

Gingiva (Normal Color)

Typically described as coral pink.

Marginal gingiva size

Ranges from $0$ to $2\,mm$.

Attached gingiva size

Typically measures $9\,mm$.

Gingival Contour

Described as being scalloped in shape.

Gingival Consistency

Firm and resilient.

Stippling

The surface texture of the gingiva, which is absent over the marginal gingiva.

Marginal Gingiva

The terminal edge or border of the gingiva surrounding the teeth in a collarlike fashion, also called unattached gingiva.

Free gingival groove

A shallow linear depression that demarcates the marginal gingiva from the adjacent attached gingiva.

Gingival Sulcus

The space between the free gingiva and the tooth.

Clinically normal probing depth

The depth of a normal gingival sulcus, typically measuring $2$ to $3\,mm$.

Healthy sulcus probe range

A measurement of $1$ to $3\,mm$ where the probe tip touches the tooth near the CEJ.

Width of attached gingiva

The distance between the mucogingival junction and the projection of the bottom of the gingival sulcus.

Interdental Gingiva

The part of the gingiva that occupies the gingival embrasure (interproximal space).

Col

The valley-like shape the interdental gingiva can take, alongside a pyramidal shape.

Oral epithelium

The primary barrier between the oral environment and deeper tissues.

Sulcular epithelium

The specific epithelium that lines the gingival sulcus.

Junctional epithelium

A collarlike band of stratified squamous non-keratinized epithelium.

Biologic width

The natural seal protecting alveolar bone from infection, measuring a total of $2.04\,mm$.

Junctional epithelium (JE) measurement

A component of the biologic width measuring $0.97\,mm$.

Connective tissue (CT) measurement

A component of the biologic width measuring $1.07\,mm$.

Gingival fiber groups

The three main groups are Dentogingival, Circular, and Transseptal.

Alveolar mucosa appearance

Usually red, smooth, and shiny rather than pink and stippled.

Melanin

A non-hemoglobin derived brown pigment responsible for physiologic pigmentation in the skin and gingiva.

Gingival pigmentation

Presents as a diffuse, deep-purplish discoloration or irregularly shaped, brown and light-brown patches.

Desmodont

An alternative term used for the periodontal ligament.

Gomphosis

A term for the periodontal ligament referring to its nature as a socket-based joint.

Pericementum

A term for the periodontal ligament emphasizing its relation to the cementum.

Alveolodental ligament

A synonym for the periodontal ligament.

Periodontal membrane

Another name for the periodontal ligament structure.

PDL Shape

Described as having the shape of an hourglass.

Narrowest point of PDL

Located at the midlevel of the ligament.

Periodontal ligament width

Approximately $0.21\,mm$.

Supportive function of PDL

Attaches teeth to bone, transmits forces, keeps tissue relationships, acts as a shock absorber, and protects vessels/nerves.

Sensory function of PDL

Transmits tactile, pressure, and pain sensations via trigeminal pathways.

Nutritive function of PDL

Supplies nutrients to cementum, bone, and gingiva through blood vessels and lymphatics.

Formative function of PDL

Maintains regenerative capacity and helps in the formation of cementum and bone.

Homeostasis function of PDL

Helps in the formation and resorption of cementum/bone during physiologic tooth movement and repair.

Osteoblasts

Synthetic cells in the PDL that form alveolar bone.

Fibroblasts (Synthetic)

Cells in the PDL that produce collagen.

Cementoblasts

Cells forming the lining of the cementum.

Osteoclasts

Resorptive cells responsible for bone breakdown.

Cementoclasts

Resorptive cells responsible for cementum breakdown.

Epithelial cell rest of Malassez

Specific epithelial cells found as part of the cellular composition of the PDL.

Tropocollagen

Formed by fibroblasts and clustered to make microfibrils in the PDL.

Principal fibers

The most important collagenous elements of the PDL that form a continuous network between tooth and bone.

Sharpey's fibers

The terminal portions of the principal fibers that insert into the cementum and bone.

Collagen Type I

The specific type of collagen that makes up the principal fibers of the periodontal ligament.

Reticular fibers

Secondary fibers in the PDL composed of Collagen Type III.

Basal Lamina (PDL)

Contains Collagen Type IV.

Transseptal fiber group

Fibers extending interproximally over the alveolar crest, reconstructed even after bone destruction in disease.

Alveolar crest group

Fibers extending obliquely from the cementum just beneath the JE to prevent extrusion and resist lateral movements.

Horizontal crest group

Fibers extending at right angles to the long axis of the tooth from cementum to alveolar bone.

Oblique fiber group

The largest group of periodontal fibers that bears the brunt of vertical masticatory stresses.

Apical fiber group

Fibers radiating from the cementum to the bone at the fundus of the socket; not visible with incomplete roots.

Interradicular group

Fibers that fan out from the cementum in the furcation areas of multirooted teeth.

Anatomical crown

The portion of the tooth that is covered by enamel.

Clinical crown

The portion of the tooth that is visible in the mouth.

Anatomical root

The portion of the tooth that is covered with cementum.

Clinical root

The portion of the tooth which is not visible to the mouth.

Cementum

The calcified avascular mesenchymal tissue forming the outer covering of the anatomic root.

Cementum Thickness (Cervix)

Varies from $16$ to $60\,\mu m$.

Cementum Thickness (Apex)

Varies from $150$ to $200\,\mu m$.

Mesial Migration/Drift

A functional process that results in cementum being thicker on distal surfaces than mesial surfaces.

Cementodentinal junction

The interface between dentin and cementum.

OMG (Cementum)

An acronym for the types of cementum covering root frequency: Overlapping, Meet, Gap.

Alveolar bone function

Provides osseous attachment to the forming PDL as the tooth erupts and disappears when the tooth is lost.

Alveolar process

The portion of the maxilla and mandible that forms and supports the tooth sockets.

Cribriform plates

Also known as lamina dura or alveolar bone proper, these line the tooth socket.

Interdental septum

Consists of cancellous bone bordered by socket wall cribriform plates between approximating teeth.

Tissue desiccation

The drying out of tissues, which is a general feature of aging in the periodontium.

Age changes in Attached Gingiva

The width of this tissue increases with age.

Age changes in Stippling

This surface texture feature usually disappears with age.

Age changes in PDL Matrix

Includes decreased organic matrix production and decreased number of fibroblasts.

Age changes in Cementum

Characterized by an increase in cemental width and a decrease in permeability.

Age changes in Alveolar Bone

Includes osteoporosis, reduction in metabolism, and decreased healing capacity after age $30$.