Cementum 310853 224041945 2008-07-07T01:36:35Z Kyle the bot 3115531 robot Adding: [[bs:Cement (zub)]] [[Image:The Periodontium.jpg|280px|thumb|right|The '''cementum''' is the surface layer of the tooth root ''(B)''. Rather than being a passive entity like paint on a wall, cementum is a dynamic entity within the [[periodontium]]. It is attached to the [[alveolar bone]] ''(C)'' by the fibers of the [[periodontal ligament]] and to the soft tissue of the [[gingiva]] by the [[gingival fibers]] ''(H)''.]] '''Cementum'''<ref>{{cite web |url=http://www.dentalfind.com/glossary/cementum.html |title=Cementum |date=2007-01-01}}</ref> is a specialized calcified substance covering the root of a [[teeth|tooth]]. Cementum 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 principal role of cementen within the tooth is to serve as a medium by which the [[periodontal ligament]]s 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 cementum is known as ''acellular cementum'' due to its lack of cellular components, and covers approximately 1/3-1/2 of the root. The more permeable form of cementen, ''cellular cementum'', covers 1/3-1/2 of the root apex, where it binds to the dentin. There is also a third type of cementum, ''afibrillar cementum'', which sometimes extends onto the enamel of the tooth. The chemical makeup of cementum is similar to that of bone, but it lacks vascularization. Volumetrically, it is approximately 45% inorganic material (mainly [[hydroxyapatite]]), 33% organic material (mainly [[collagen]] type1) and 22% water. == See also == *[[Head and neck anatomy]] == References == <references/> == External links == * [http://www.dentalfind.com/glossary/cementum.html Definition] {{Periodontology}} {{dentistry-stub}} {{Digestive-stub}} [[Category:Teeth]] [[Category:Dentistry]] [[Category:Periodontology]] [[zh-min-nan:Khí-kut-chit]] [[bs:Cement (zub)]] [[bg:Зъбен цимент]] [[de:Wurzelzement]] [[fr:Cément]] [[it:Cemento (anatomia)]] [[hu:Fogcement]] [[ja:セメント質]] [[pl:Cement (histologia)]] [[pt:Cemento]] [[sr:Цемент (зуб)]]