Classification of periodontal diseases: the dilemma continues.

Classification is the systematic separation and organization of knowledge about diseases. Even though it is ideal that classification of periodontal diseases be based solely on etiologic agents, it is not always practical, since many factors influence the manifestations of periodontal disease. Until recently, the 1989 American Academy of Periodontology classification system was used. However, this classification system was soon criticized because of its drawbacks. In the 1999 world workshop, the classification was revised, and an elaborate new classification system was agreed upon. This paper reviews the current literature and compiles the views of various authors regarding the 1989 and 1999 world workshop classifications.