In order to understand how disease processes can affect the oral cavity, it is important to know the structure of the periodontium. This includes the gingival tissue and its supporting bone. The gingiva usually exhibits one of the first signs of inflammation through redness, bleeding or swelling. Although, this is not necessarily a sign of periodontal involvement it is imperative to understand the underlying structures and how they interact.
Structure of the Gingiva
The normal gingiva may range in color from light coral pink to heavily pigmented. It is normally stippled in appearance (resembling an orange peel). The makeup of the gingival tissue varies according to its location and function. There are two types of gingiva and several important anatomic regions.
The attachment of the tooth to the surrounding and supporting structures (bone) is accomplished through the cementum of the tooth, periodontal ligaments and the alveolar bone. The root of the tooth (cementum) is attached to the underlying bone by a series of periodontal fibers that make up the periodontal ligament and allow for minor movement of the tooth in the socket without damage to the tooth or the underlying structures. These fibers are classified apical, oblique, horizontal, alveolar crest and interradicular fibers.
The alveolar bone supports the teeth and is covered by gingival tissue. It contains several different types of bone. The inner and outer surfaces of the bone are made up of dense cortical plates. The portion between the cortical plates is called trabecular or cancellous bone. It resembles a sponge in appearance and has many irregular spaces within. The wall of the tooth socket is made of lamina dura, which is a thin, dense bone where the periodontal ligament is attached.