The Periodontium
the functional unit that keeps teeth in place
What is it? What does it do?
The Periodontium
is the
functional unit of tissue that supports the teeth.
Comprised of two parts
The Gingiva
also known as the gums, and its function is to protect the underlying tissue
The Attachment Apparatus
the tissues that attach the tooth to the alveolar process
The Gingiva
made up of masticatory mucosa, which is thick, keratinized epithelium and underlying mucosa consisting of dense collagen fibers
Attached Gingiva
This is the part of the gingiva that is attached to the underlying bone and cementum.
Free Gingiva
Also known as marginal gingiva; this is the part of the gingiva that is unattached and forms a cuff-like space around the tooth.
Interdental Gingiva
Also known as interdental papilla; this is the tissue that occupies the interproximal area between two teeth. The tip and lateral borders are continuous with the free gingiva.
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Mucogingival Junction
A boundary located at the apical boundary of the attached gingiva. The mucogingival junction is the connection between the attached gingiva and the alveolar mucosa.
Col
Made up of nonkeratinized tissue, making it more susceptible to disease and the beginning site of most periodontal infections. The col is a valley-like depression between the lingual/palatal and facial papillae that conforms to the shape of the proximal contact area.
Oral Epithelium
Covers the free gingiva from the gingival groove over the gingival margin. It is composed of keratinized stratified squamous epithelium (hard tissue).
Gingival Sulcus
The space between the free gingiva and the tooth. The gingival sulcus has an average depth of 1.8 millimeters (in health).
Junctional Epithelium
Located at the base of the sulcus, the junctional epithelium encircles the tooth to form a tight seal and acts as the attachment interface between the tooth and the gingiva.
The Attachment Apparatus
Consists of three parts: the periodontal ligament (PDL), the cementum, and the alveolar bone.
Gingival Fiber Groups
Dentogingival
extends from the cementum near the CEJ to the free gingiva
Principal Fiber Groups
Oblique Fibers
extend from the root towards the occlusal surface
Cementum
the thin layer of calcified connective tissue that covers the outer surface of the root of the tooth from the cementoenamel junction to the apex
Functions include providing a medium for attachment of the periodontal fiber groups and sealing the tubules of the root dentin.
There are two types of cementum:
Primary Cementum - also known as acellular cementum. It is located on the cervical half of the root and it forms in conjunction with the root formation and eruption.
Secondary Cementum - also known as cellular cementum. It forms in the apical third after the tooth erupts. It contains cells for forming cementum.
