Lec 1: Anatomy of the Periodontium Flashcards by sandra alcazar

What is the main function of the periodontium?

To maintain teeth in function

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What are the 4 principal components of the periodontium?

Gingiva
Periodontal ligaments
Cementum
Alveolar bone

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Those part of the masticatory mucosa surrounding the cervical part of teeth and covering the alveolar process.

Gingiva

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Morphologic/anatomic divisions of the gingiva?

Marginal
Attached
Interdental papilla

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4 factors that influence color of the gingiva?

Melanin pigmentation
Degree of keratinization
Degree of vascularity
Fibrous nature of the connective tissue

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Terminal edge or border of the gingiva that surrounds the teeth in collar like fashion.

Marginal gingiva

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Shallow linear depression that demarcates free gingiva to attached gingiva..

Free gingival groove

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This forms the soft tissue wall of the gingival sulcus.

Marginal gingiva

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The most apical point of the marginal gingival scallop.

Gingival zenith

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The most coronal portion of the gingiva.

Free gingival margin

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What is the location of a healthy free gingival margin?

1-2mm coronal to CEJ

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What is the location of a healthy free gingival groove?

1-1.5mm apical to gingival margin at the base of the sulcus

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A V-shaped shallow crevice or space around the tooth bounded by the surface of the tooth on one side and the epithelium lining of the in margin of the gingiva on the other side.

Gingival sulcus

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What is the probing depth of normal gingival sulcus?

0.5-3mm

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Transudate that emerges from gingival sulcus, containing a variety of enzymes and cells, particularly desquamating epithelium and neutrophils.

Gingival crevicular fluid

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An increase in the crevicular flow is a sign of?

Inflammation

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Once inflammation has occured, the GCF is now referred as?

Inflammatory exudate

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Continuous with the marginal gingiva, firm, resilient, stippled.

Attached gingiva

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Tightly bound to the underlying periosteum of alveolar bone and to the cementum by connective tissue fibers and epithelial attachment.

Attached gingiva

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The attached gingiva is demarcated by?

Mucogingival junction

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Epithelial projections that extend into gingival connective tissue.

Rete pegs

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What do you call the depression, orange peel surface, or irregular surface texture of the attached gingiva?

Stippling

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A recognizable borderline separating the alveolar mucosa from the gingival mucosa.

Mucogingival junction

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The mucogingival junction is absent in what area?

Maxillary lingual area

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Occupies the gingival embrasure, which is the interproximal space beneath the area of tooth contact.

Interdental papilla

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

Col

The lateral borders and tips of the interdental papillae are formed by the _________ of the adjoining teeth, while he intervening portion consists of _____________.

marginal gingiva; attached gingiva

* Extending from gingival margin to the mucogingival junction. * Keratinized stratified squamous epithelium. * Has rete pegs.

Oral epithelium

* Lines the gingival sulcus. * Non-keratinized stratified squamous epithelium * No rete pegs.

Sulcular epithelium

* Joints the inner surface of the gingiva to the tooth. * Non keratinized stratified squamous epithelium * No rete pegs

Junctional epithelium

What are the 3 areas of gingival epithelium?

Oral, sulcular, and junctional epithelium

The junctional epithelium is connected to the tooth by __________ and _________.

Internal basal lamina; hemidesmosomes

Serves as route for passage of fluid and cells from the connective tissue into the sulcus and for the passage of bacteria and bacteria products from the sulcus into the connective tissue.

Junctional epithelium

Length of a healthy junctional epithelium

0.25 to 1.35 mm

Inner layer of cells of the junctional epithelium that actually provides the attachment of gingiva to the tooth.

Epithelial attachment

The epithelial attachment consists of? (3)

Lamina lucida Lamina densa Hemidesmosomes

Helps in holding the marginal gingival tightly against the tooth.

Connective tissue

MAJOR COMPONENTS OF CONNECTIVE TISSUE: Gingival fibers (connective tissue fibers) - - - - Intercellular ground substance (or matrix) - - - Cells: - - - - Vessels and nerves

Gingival fibers (connective tissue fibers) - Type I collagen fibers (60%) - Oxytalan - Elaunin - Elastin fibers Intercellular ground substance (or matrix) - Proteoglycans - Glycoproteins - Water Cells: - Fibroblasts - Mast cells - Macrophages (histiocytes) - Inflammatory cells Vessels and nerves

Enumerate the gingival fibers.

Circular Dentogingival Dentoperiosteal Alveogingival Transseptal

* Run their course in the free gingival and encircle the tooth in a cuff or ring like fashion; from cementum, across bony septum and to the other side. * Resist rotational force.

Circular fibers

Embedded in cementum of the supraalveolar portion of the root and project from here in a fan like configuration out into the free gingival tissue of facial, lingual, and interproximal spaces.

Dentogingival fibers

Embedded in the same portion of cementum, run their course apically over the vestibular and lingual bone crest and terminate in the tissue of the attached gingiva

Dentoperiosteal fibers

Insert in the crest of alveolar process and spread out through the lamina propria into the free gingiva.

Alveogingival fibers

* Extend from tooth to tooth, coronal to the alveolar crest and are embedded in the cementum of adjacent teeth. * Not found on the facial aspect and have no attachment to alveolar crestal bone. * Connect all teeth and maintain the integrity of the dental arches. * Sometimes classified as Principal Fibers of PDL.

Transseptal fibers

Soft, richly vascular and cellular specialized form of connective tissue derived from dental sac that surrounds the roots of the teeth and joints the root cementum with the alveolar bone proper.

Periodontal ligament

Normal width of the periodontal ligament.

0.1-0.2mm

The dominant component of PDL, which is made up primarily of bundles of continuous intermingling connective tissue fibers arranged in a network running from cementum to the alveolar bone; and ground substance (proteoglycans, glycoproteins, and water).

Fibrous matrix

Makes it possible to distribute and absorb trajectory of forces during mastication into the alveolar process via alveolar bone proper.

Periodontal ligament

Enumerate the principal fibers of PDL.

Alveolar crest Horizontal Oblique Apical Interradicular

* From cementum of the tooth, running apically to the crest of the alveolar bone * Counterbalance occlusal forces on the more apical fibers * Prevents extrusion of tooth * Resists lateral movements * First to be destroyed in pathologic conditions

Alveolar crest fibers

* More apical than the former and run perpendicular from tooth to alveolar bone * Responsible on why tooth movement is possible * Resist lateral forces

Horizontal fibers

* Largest group; most abundant * Runs in a coronal direction from tooth obliquely to bone * More resistant to forces along the long axis of the tooth (vertical masticatory forces) * Most likely to be found in the middle third of the root.

Oblique fibers

* Radiate around the apex of the tooth to adjacent of bone * Offer initial resistance to tooth movement in an occlusal direction; prevent tipping and dislocation of tooth * Fibers affected during acute apical pulpitis (AAP)

Apical fibers

* Fibers that can be only seen in multirooted teeth (molars, premolars) * From cementum in the furcation area to the bone within the furcation * Is to be destroyed in col de sac incidence.

Interradicular fibers

Terminal portion of collagen fibers which are embedded into the cementum and bone.

Sharpey's fibers

* It is the calcified body (rests that degenerates) found in the periodontal ligament. * From apposition of cementum.

Cementicle

Most common cell of the PDL

Fibroblasts

Types of cells in the PDL (6)

1. Fibroblasts 2. Osteoclasts and osteoblasts 3. Cementoclasts and cementoblasts 4. Reserve cells or undifferentiated mesenchymal cells 5. Mast cells (histamine and heparin), macrophages, eosinophils, cementicles 6. Epithelial rest of Malassez

Type of collagen fiber in the PDL

Collagen type 1

Nerve fibers in the PDL arises from the branches of?

Trigeminal nerve (CN V)

Pain; most abundant; Merkel cells; root length

Free nerve endings

Pressure; proprioception; root apex

Ruffini corpuscle

Pressure; mechanoreceptors

Pacinian corpuscle

Midroot (nerve fibers)

Coiled Meissner's endings

Apex (nerve fibers)

Encapsulated spindle endings

Vasculature for the PDL arises from?

Maxillary artery

Lymph from the PDL drains to?

Submandibular lymph nodes

What are the 5 roles of the PDL?

Mechanical Formative Nutritive Homeostatic Sensory

Role of PDL: Attach tooth to bone; provide a cushion for absorption and transmission.

Mechanical

Role of PDL: Contains cells that form periodontium.

Formative

Role of PDL: Contains vascular network providing nutrients.

Nutritive

Role of PDL: Maintain balance of function

Homeostatic

Role of PDL: Has afferent nerve fibers for pain (free), pressure (Spindle-like) and proprioception (Ruffini-like receptor & Meissner’s corpuscle).

Sensory

Specialized calcified tissue covering the root surface.

Cementum

Cementum is thicker in the _____ of the root.

Apical third

4 differences of cementum with the bone?

1. Avascular 2. No innervations 3. Fewer cells 4. No resorption/remodelling

Origin of the cementum

Ectomesenchymal cells of the dental sac

Composition of the cementum?

65% hydroxyapatite 32% collagen 3% water

Classifications of cementum: > By formation: - - > By cellularity: - -

> By formation: - Primary - Secondary > By cellularity: - Acellular - Cellular

* First formed cementum * Covers coronal cementum * Is acellular * Consists of extrinsic collagen fibers

Primary cementum

* Covers apical cementum * May be either acellular or cellular * Consists of mixed collagen fibers

Secondary cementum

* Slowly formed before the tooth erupts to reach the occlusal plane. * Devoid of cells. * Found principally in coronal areas (cervical half) of the roots and is characterized by dense layers of calcified collagen seen in coronal cementum separated by growth lines.

Acellular cementum

These are periodontal ligament extrinsic fibers embedded in the cementum.

Sharpey's fibers

Main function of acellular cementum.

Anchorage

* Rapidly formed after tooth reaches occlusal plane. * Most commonly found in apical areas of the tooth, and in furcation areas of multirooted teeth. * Within are masses of cementocytes, cementoblasts, and cementoclasts. * Forms after passive tooth eruption in response to function.

Cellular cementum

Main function of cellular cementum?

Adaptation and repair

* Parts of maxilla and mandible that form and support the sockets of the teeth. * Main function: to distribute and absorbed forces generated by mastication.

Alveolar bone

Two main components of the alveolar bone?

Alveolar bone proper (cribriform plate) Supporting alveolar bone

What is the shape of the alveolar crest?

Parallel to the CEJ

What is the location of a healthy alveolar crest?

1.5-2mm apical to CEJ

Dimension from the crest of the alveolar bone to the base of the sulcus.

Biological width

Normal biological width?

2.04mm

Normal width of the connective tissue?

1.07mm

Normal width of the epithelial attachment?

0.97mm

2 types of bone

Compact Trabecular

Cortical, dense, hard bone (solid bone mass)

Compact bone

Spongy, cancellous, soft bone (honeycomb appearance)

Trabecular bone

Unit structure of bone

Osteon / Haversian system

One osteon is connected to another through?

Canaliculi

3 types of lamellae of bone

Circumferential Concentric Interstitial

2 types of coverings of bone

Periosteum Endosteum

External surface of bone

Periosteum

Inner, surrounds bone marrow

Endosteum

2 types of bone formation

Endochondral Intramembranous

Indirect method; cartilage becomes bone Ex: Condyle, ethmoid bone, inferior conchae, sphenoid

Endochondral

Direct method; bone cells secrete bone Ex: maxillary and mandibular bone

Intramembranous

Thin layer of cortical bone that immediately surrounds roots of the tooth and into which periodontal ligament fibers (Sharpey’s fibers) are embedded.

Alveolar bone proper (cribriform plate)

Blood supply of: Socket and lamina dura

Intraseptal artery

Blood supply of: Gingiva

Supraperiosteal blood vessels

Blood supply of: Junctional epithelium

Dentogingival plexus

Blood supply of: Oral epithelium of the free and attached gingiva

Subepithelial plexus

Lymphatic drainage: Buccal gingiva of the maxilla, and buccal and lingual of the mandibular premolar and molar region.

Submandibular lymph nodes (angle of the jaw)

Lymphatic drainage: Mandibular incisors

Submental

Lymphatic drainage: Third molars

Jugulodigastric

Lymphatic drainage: Labial and lingual gingival of the mandibular incisors

Submental (digastric)

Lymphatic drainage: Palatal gingival

Deep cervical lymph nodes (neck area)