Structure and Junctions - Cementum is composed of cementocytes, located in lacunae with canaliculi or canals. - Cementum canals are oriented towards the periodontal ligament and contain cementocytic processes for nutrient diffusion. - Cementoblasts can form subsequent layers of cementum if the tooth is injured. - The cementum joins the enamel to form the cementoenamel junction (CEJ). - The dentinocemental junction (DCJ) is formed by the apposition of cementum over the dentin. - The attachment of cementum to the dentin is firm but not completely understood. - The DCJ is a relatively smooth area in the permanent tooth. - Cementum deposition helps in minor repair of any resorption to maintain attachment.

Types of Cementum - Acellular extrinsic fiber cementum contains perpendicular collagen fibers and attaches the tooth to the alveolar bone. - Cellular cementum is thick and contains both extrinsic and intrinsic collagen fibers. - The first cementum formed during tooth development is acellular extrinsic fiber cementum. - Main types of cementum include acellular afibrillar cementum, acellular extrinsic fiber cementum, cellular intrinsic fiber cementum, and mixed stratified cementum.

Composition - Cementum is slightly softer than dentin. - It consists of about 45-50% inorganic material (hydroxylapatite) and 50-55% organic matter and water. - The organic portion is primarily composed of collagen and proteoglycans. - Cementum receives nutrition from the surrounding periodontal ligament. - Cementum is light yellow and has the highest fluoride content among mineralised tissues.

DNA Studies - Cementum has five times the amount of mitochondrial DNA compared to dentin. - DNA extraction and genetic analysis results from dental tissue are variable and unpredictable. - The quantity of DNA available in dentin is affected by age and dental disease. - The quantity of DNA available in cementum is not affected by age and dental disease.

Other Information - Cementum has a dynamic tissue covering of the root. - Its structure, function, and development have been studied. - Acellular extrinsic fiber cementum has been analyzed using Raman analysis. - Cementum is part of the periodontium. - It has potential functions that are still being explored.