The dentogingival junction is an anatomical and functional interface between the gingiva and the tooth structure.
It provides attachment of the gingiva to the enamel surface via hemidesmosomes. Biologic width is the term applied to the dimensions of the dentogingival junction.
It was first described by Sicher in 1959. Biologic width is the apicocoronal distance in which the functional epithelium and supracrestal connective tissue fibers are attached to the tooth.
The body maintains the biologic width as a stable dimension. When the biologic width is encroached upon and injured by extension of restorative preparations and materials in this area, uncontrolled inflammation results as the body tries to reestablish this dimension.
Gingival apparatus maintains the free gingival and functional epithelium in close approximation to the tooth.
The attachment of the functional epithelium to the tooth is reinforced with the gingival fibers, which brace the gingival against the tooth surface.
So that the gingival fibers along with functional epithelium are considered as a functional unit referred to as "Dentogingival unit".
1. Epithelial component is derived from reduced dental (enamel) epithelium and oral epithelium.
In some references, the epithelial part derived from the reduced dental epithelium is referred as primary attached epithelium or initial functional epithelium. While in other references, a definitive epithelium replaces this initial one 3-4 years after the tooth erupts.
2. The connective tissue component is derived from the lamina propria of the oral mucosa.
Gargoyle and colleagues studied the anatomy of the dentogingival junction and quantified the average as a constant 2.04 mm (the epithelial attachment is 0.97 mm, and connective is 1.07 mm).
The distance is measured histological from the most coronal part of the functional epithelium (base of the sulcus) to the crest of the alveolar bone.