The term periodontium arises from greek words "peri" meaning around and "odont" meaning tooth. Tissues that invest and support the teeth are collectively termed PERIODONTIUM. It consists of four principal components: two mineralized (i.e.alveolar bone & cementum) and two fibrous components (i.e. periodontal ligament & gingival),also called THE ATTACHMENT APPARATUS or THE SUPPORTING TISSUES OF THE TEETH. The fibrous investing tissue, covered by keratinized epithelium, which immediately surrounds a tooth and is contiguous with its periodontal ligament and with the mucosal tissues of the mouth. The gingiva covers the alveolar process, and it is the only one of the periodontal tissues that under healthy conditions are directly visible upon inspection. Periodontal ligament is an unique multifunctional soft specialized , vascular and highly cellular connective tissue that surrounds the tooth root and connects it to the inner wall of the alveolar bone. It is continuous with the connective tissue of the gingiva and communication with marrow spaces thro vascular channels in the bone.