Ch. 1 Periodontium: The tooth supporting structures

Periodontium

Functional system of tissues that surrounds teeth and attaches them to jawbone

Perio = around

Odontos = tooth

*aka- supporting tissues of teeth, attachment apparatus

Tissues compromising the Periodontium

• Gingiva

• Cementum

• Periodontal Ligament

• Alveolar Bone

Function of the Gingiva

• Provides a tissue seal around the cervical portion (neck) of the tooth

• Covers the alveolar processes of the jaws

• Holds the tissue against the tooth during mastication

Function of the Periodontal Ligament

• Suspends and maintains the tooth in its socket

Function of Cementum

• Anchors the ends of the periodontal ligament fibers to the tooth so that the tooth stays in its socket

• Protects the dentin of the root

Function of the Alveolar Bone

• Surrounds and Supports the roots of the tooth

Gingiva

• Contour and shape of gingival margin approximates scalloped curvature of cementoenamel junction (CEJ)

Position may be age dependent

Health young- at or coronal to the CEJ

Healthy older- apical to CEJ

• Attached by junctional epithelium

• Composed of thin outer layer of epithelium and underlying layer of connective tissue

• has 4 anatomical areas

• function- protects underlying tooth-supporting structures of the periodontium from oral environment

Boundaries of the Gingiva

Gingival margin

Alveolar mucosa: dark, red smooth shiny

Free gingival groove - Gingiva Demarcations

shallow linear depression separating free and attached gingiva (may be hard to see with the naked eye)

Mucogingival junction - Gingival Demarcation

where the pink attached gingiva meets the red alveolar mucosa (clinically visible)

What are the two gingival demarcations?

Free gingival groove

Mucogingival Junction

Free gingiva

• Unattached portion surrounding tooth in CEJ region

• Also called unattached gingiva or marginal gingiva

• Surrounds tooth in turtleneck manner

• Attaches by junctional epithelium

• Fits closely around tooth, but not directly attached

• Forms soft tissue lateral wall of gingival sulcus

• Free gingival margin- thin, rounded edge where free gingiva meets tooth follows scalloped, curved contours of underlying CEJ.

Attached gingiva

• Continuous with free gingiva

• Tightly bound to - underlying cementum on cervical-third of periosteum of alveolar bone

• WIDEST in incisors and molar regions

• NARROWEST in premolar regions

• NOT measured on palate

• Function : allows gingival tissue to withstand mechanical forces created during chewing, speaking and tooth brushing

• prevents free gingiva from being pulled apically from tooth when tension is applies to alveolar mucosa ( ex. if you pull or tug on lip, the gingiva helps keep it in place)

Color of attached Gingiva

Pale or light coral pink when healthy

** May have physiologic pigmentation caused by increased melanin production

Texture of attached gingiva

May exhibit stippling on healthy attached and interdental gingiva

** NOT always present

Interdental gingiva

• Portion of gingiva that fills interdental embrasure between two adjacent teeth apical to contact area

• Consist of facial papillae and lingual papillae

• interdental col - depression apical to contact area of adjacent teeth that connects facial and lingual papillae

• Function: Prevents food from packing between teeth when chewing

Gingival Sulcus

• V-shaped shallow space between free gingiva and tooth surface

• Encircles neck of tooth

• 1-3mm deep when clinically healthy (measured with periodontal probe)

• Base interfaces with most coronal portion of junctional epithelium

Gingival Crevicular Fluid

• also called Gingival sulcular fluid

• seeps from underlying connective tissue

• little to none in healthy sulcus

• Flow increases in response to gingival stimulation (greatly increase with inflammation)

Which part of the gingiva is tightly bound to the underlying cementum and alveolar bone?

attached gingiva

What is the base of the gingival sulcus formed by?

most coronal junction of the coronal epithelium

Periodontal Ligament (PDL)

• Network of soft connective tissue fibers that attach root of the tooth to bony walls of tooth socket

• Primarily composed of dense fibrous connective tissue (fibers attach to root cementum and alveolar bone)

• Serves to:

Connect tooth to alveolar process

support tooth in socket

Absorb mechanical loads placed on tooth

Functions of the Periodontal Ligament (5)

• Supportive

• Sensory

• Nutritive

• Formative

• Remodeling

Supportive

suspends and maintains tooth in socket

Sensory

nerve endings relay sensory information

Nutritive

Blood vessels provide oxygen and nutrients

Formative

certain components build and maintain attachment apparatus and may aid periodontal regeneration

Remodeling

can remodel alveolar bone in response to pressure

Cementum

• Thin layer of hard, mineralized tissue that covers surface of root

• Overlies dentin

• Softer than dentin or enamel

• 55% organic, 45% inorganic

• More resistant to resorption than bone (makes orthodontic treatment possible)

• undergoes continuous resorption and repair throughout lifetime of tooth

• becomes thicker with age

• two types: CELLULAR and ACELLULAR

Acellular Cementum

• Forms BEFORE teeth are in occlusion

• Devoid of cells

• Covers cervical two-thirds of root

• plays an important role in tooth support

Cellular Cementum

• Forms AFTER teeth have reached occlusion

• Composed of cementocytes

• Covers apical one-third of root

• Compensates for active eruption and normal tooth wear by continuous deposition of cementum