Periodontium is the tissue that immediately surrounds and supports the teeth. It consists of alveolar bone, periosteum, periodontal ligament, gingival sulcus, and gingiva; each of these components contributes to stabilizing the tooth within the jaws.
The alveolar bone is the bone that surround the teeth. When a tooth is removed, alveolar bone around the tooth will start to get resorbed. It is composed of cancellous bone, also known as spongy bone. It is located between cortical plates and is permeated by blood vessels and marrow spaces.
The periosteum is dense connective tissue attached to the outer surface of the bone.
The tooth is anchored to alveolar bone by the attachment of the periodontal ligament to the periosteum and the cementum of each tooth root. The periodontal ligament follows the outline of the tooth root and extends superiorly to the base of gingival sulcus.
Cementum is a specialized calcified substance covering the root of a tooth.
The gingival sulcus is line internally by a thin layer of epithelium cells called junctional epithelium. This epithelium provides the barrier to the ingress of bacteria. In healthy gum, the gingival sulcus is a crevice that is less than 3mm deep.
Periodontal pocket – gingival sulcus that extend deep down
A periodontal pocket is a gingival sulcus that has experienced apical (or downward) extension of the epithelial attachment beyond 3mm because of repeated inflammatory insults and poor oral hygiene. Although accumulation of bacterial plaque is the most important factor influencing the health of the periodontium, position of the tooth within the arch, occlusal loading, parafunctional habits, appliances, drugs and frenal attachments also effect periodontal health and the development of periodontal pockets.