What makes cementum a unique structure?

Cementum was first described by Denton GB in 1835 as a calcified, avascular mesenchymal tissue that covers the entire root surface. It approximately comprises of 50% of hydroxyappetite and 50% of organic matrix which consist of non collagenous and collagenous proteins. Protein extract of mature cementum promotes cell attachment, migration and stimulates protein synthesis of gingival fibroblast and periodontal ligament cells. One of the main functions of the cementum is to anchor the principle collagen fibers of the periodontal ligament to the root surface. It plays a role in adaptive and reparative function to maintain the occlusal relationship and to predict the integrity of the root surface. Regeneration of cementum on denuded root surface has been the subject of interest in the modern era of periodontal plastic surgery.