<unk>  is a specialized calcified substance covering the root of a tooth.<unk>  is excreted by cells called cementoblasts within the root of the tooth and is thickest at the root apex. Its coloration is yellowish and it is softer than enamel and dentin due to being less mineralized.
The principle role of cementen within the tooth is to serve as a medium by which the periodontal ligaments can attach to the tooth for stability. Hence, its bottom surface is tangent to the periodontal ligaments running through the jaw (via collagen fibers), and the upper portion of the surface is firmly cemented to the dentin of the tooth. It also meets the enamel lower on the tooth at the cemento-enamel junction. Here the<unk>  is known as acellular<unk>  due to its lack of cellular components, and covers approximately 1/3-1/2 of the root. The more permeable form of cementen, cellular<unk> , covers 1/3-1/2 of the root apex, where it binds to the dentin. There is also a third type of<unk> , afibrillar<unk> , which sometimes extends onto the enamel of the tooth.
The chemical makeup of<unk>  is similar to that of bone, but it lacks vascularization. Volumetrically, it is approximately 65% inorganic material (mainly hydroxyapatite), 23% organic material (mainly collagen type1]) and 12% water.
Cementum
Vesicle 
Kerion
Dermatophyllum
Phlyctenule
Malleus
Kerosene
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