1 Periodontium: The Tooth Supporting Structures

Chapter 1: Periodontium - The Tooth Supporting Structures

Foundations

• Authors: Jill S. Gehrig, Daniel E. Shin

• For the Dental Hygienist, Sixth Edition

• Copyright © 2024 by Jones & Bartlett Learning, LLC

• Periodontium: A functional system of tissues that surrounds teeth and attaches them to jawbone

  • Also known as:

  • Supporting tissues of teeth

  • Attachment apparatus

Healthy Periodontium

• Key components of healthy periodontium:

  • Sulcus

  • Gingiva

  • Crest of alveolar bone

  • Periodontal ligament

  • Cementum

  • Alveolar bone

Structures of the Periodontium and Their Functions

A comprehensive overview of the Periodontium's structures and their roles:

Gingiva

• Description: Part of mucosa surrounding cervical portions of teeth and covering alveolar processes

• Functions:

  • 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

Periodontal Ligament

• Description: Network of soft connective tissue fibers attaching root of tooth to bony walls of tooth socket

• Functions:

  • Suspends and maintains the tooth in its socket

  • Absorbs mechanical loads placed on tooth

  • Connects tooth to alveolar process

Cementum

• Description: Thin layer of hard, mineralized tissue that covers the root surface; overlying dentin

• Functions:

  • Protects the dentin of the root

  • Provides attachment for periodontal ligaments

Alveolar Bone

• Description: Bone of upper or lower jaw that supports the roots of teeth

• Functions:

  • Acts as a housing for the teeth

  • Forms bony sockets to support and protect roots

Detailed Examination of the Gingiva

• Structure and Shape:

  • Contour approximates scalloped curvature of cementoenamel junction (CEJ)

  • Position may vary with age

  • Anchored by junctional epithelium

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

• Anatomical Areas of Gingiva:

  • Four key areas:

  • Free gingiva

  • Gingival sulcus

  • Interdental gingiva

  • Attached gingiva

  • Primary function: Protects underlying tooth-supporting structures from the oral environment

• Boundaries of Gingiva:

  • Gingival margin, alveolar mucosa

  • Important demarcations include free gingival groove and mucogingival junction

• Free Gingiva:

  • Surrounds tooth in CEJ region, also known as unattached or marginal gingiva

  • Fits closely around tooth, crown margin

  • Forms lateral wall of gingival sulcus

Width and Characteristics of Attached Gingiva

• Width Measurement:

  • Widest in incisor and molar regions, narrowest in premolar regions

  • Not measured on palate

  • Belief in a minimum of 2 mm of keratinized gingiva for health is being re-evaluated

• Color and Texture:

  • Healthy attached gingiva is pale or light coral pink; pigmentation may occur

  • Texture may exhibit stippling

  • Stippling is not always present in healthy adults

• Function of Attached Gingiva:

  • Provides resistance against mechanical forces from chewing, speaking, and tooth brushing

  • Prevents free gingiva from being pulled away from tooth under pressure

Interdental Gingiva

• Definition: Portion of gingiva filling interdental embrasure between adjacent teeth

• Structure includes facial papilla and lingual papilla

• Interdental col connects facial and lingual papillae, preventing food packing

Gingival Sulcus

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

• Clinical depth: 1 to 3 mm in healthy individuals

• Measured with a periodontal probe

Gingival Crevicular Fluid (GCF)

• Also known as gingival sulcular fluid

• Seepage from connective tissue

• Minimum flow in healthy sulcus; increases with stimulation or inflammation

Periodontal Ligament (PDL)

• Definition: A network of soft connective tissue fibers attaching the root of the tooth to the bony socket walls

• Composition: Dense fibrous connective tissue

  • Connects to root cementum and alveolar bone

• Functions:

  • Supports tooth in socket

  • Absorbs mechanical loads

  • Contains nerve endings and blood vessels

Cementum

• Definition: Thin layer of hard, mineralized tissue covering the root

• Composition: 55% organic and 45% inorganic

• Types of Cementum:

  • Acellular cementum: Devoid of cells, present before teeth occlude

  • Covers cervical two-thirds of root

  • Cellular cementum: Forms after occlusion, contains cementocytes

  • Covers apical one-third of root

• Continuous deposition compensates for wear and active eruption

Alveolar Bone (Alveolar Process)

• Definition: Bone surrounding and supporting the roots of teeth

• Composition: 60% inorganic, 25% organic, 15% water

• Resorption occurs when teeth are extracted

Layers of the Alveolar Process

• Alveolar Bone Proper:

  • Thin layer lining the socket, containing alveolus and foramina

• Cortical Bone (Cortical Plate):

  • Compact bone forming the outer wall, varies in thickness across tooth types

  • Alveolar crest: Meets teeth in scalloped form

• Cancellous Bone (Spongy Bone):

  • Interior part of alveolar process, more prevalent in maxilla than mandible

Nerve Supply to the Periodontium

• Innervation from branches of trigeminal nerve (cranial nerve V)

  • Maxillary nerve (V2) for maxilla

  • Mandibular nerve (V3) for mandible

• Function: Registers pain, touch, pressure; helps in regulating chewing forces

Blood Supply to the Periodontium

• Complex network of vascular supply provides oxygen and nutrients; removes waste

• Arteries include:

  • Superior alveolar artery (maxillary)

  • Inferior alveolar artery (mandibular)

Lymphatic System and the Periodontium

• Network of lymph nodes connected by vessels, crucial for immune defense

• Lymph drainage from periodontal tissues to nodes located throughout the head and neck