Structure of periodontal tissues in health and disease *

The periodontium, defined as those tissues supporting and investing the tooth, comprises root cementum, periodontal ligament, bone lining the tooth socket (alveolar bone), and that part of the gingiva facing the tooth (dentogingival junction). The widespread occurrence of periodontal diseases and the realization that lost tissues can be repaired and, perhaps, regenerated has generated considerable interest in the factors and cells regulating their formation and maintenance. It is important to understand that each of the periodontal components has its very specialized structure and that these structural characteristics directly define function. Indeed, proper functioning of the periodontium is only achieved through structural integrity and interaction between its components. In recent years, a number of detailed descriptions of the structural and compositional features of periodontal tissues have been published (3, 5‐7, 9, 15, 17, 46, 50, 56, 58, 61); we refer the reader to these for a comprehensive description of the development, formation, and structure of periodontal tissues. The present review will focus on structure‐function relationships pertinent to understanding periodontal tissue breakdown and the repair ⁄ regeneration of affected structures.