Physical Characteristics 1-ColorLight yellowLighter in color than dentin 2- ThicknessAcellular cementum (20-50 m)Cellular cementum (150-200 m) 3- Permeability Permeable from dentin and PDL sides.Cellular C is more permeable than acellular C.
Chemical Composition45-50 % Inorganic 50-55% Organic substances substances CollagenHydroxyapatite crystals protein Polysaccharides Trace elementsCementum contains the greatest amount offluoride in all mineralized tissues
Cementum Structure C D D CAcellular cementum Cellular cementum
Acellular Cementum Thickness is 20-50 µ. It is clear and structureless Covers the coronal half of the root. Incremental lines of Salter are parallel to the surface. Sharpey’s fibers space can be seen in it .
Alternating layers ofa cellular andcellular cementumcould be seen.
Cellular Cementum Lacunae of cementocytesPDL side Cementocytes Dentin side
Cementocyte And Osteocyte Dentin side Osteocyte LacunaCanaliculi PDL side
Cementocyte And Osteocyte Dentin side OsteocyteLacuna Canaliculi Periodontal ligament side
Cellular Cementum Viable Dentin side superficial cementocytesDegenerateddeep layer’scementocytes PDL side
Incremental Lines Of SalterIn acellular C In cellular CThey are hypermineralized area with lesscollagen fibers and more ground substance
Cemento Dentinal Junction C DSmooth in permanent teeth Scalloped in deciduous teeth
Cemento Enamel Junction 10% cementum and enamel don’t meet because of 60% 30% cementum cementummeets the enamel delayed separation of epith overlaps E in a sharp line root sheath of Hertwig (area of dentin not covered by C). (afibrillar cementum)
Afibrillar CementumBefore tooth eruption, The connective tissue of the enamel at the the dental sac lay downcervical area lose its cementum on the REE covering. exposed enamel
Functions Of Cementum1- Acts as a medium for attachment of collagen fibers of PDL (Sharpey’s fibers).2- The continuous Cementoid T formation of cementum keeps the attachment apparatus intact. Cementoblast
3- Cementum deposition epically compensate for the attrition.4- It is a major reparative tissue( as in case of fracture or resorption of root)
Cementogenesis• 1- Matrix formation • 2- Mineralization and Maturation Collagen Ground Hydroxy apatite fiber type I substance crystals
1- Matrix formation • Cementum is formed during root Cementoblasts formation D HERFuture C E J Epith. Diaph.
Cementoblast is a protein forming and secreting cell. Collagen fibers + ground substance. D Large nucleus with dispersed chromatin threads. Cementoblast RER Golgi apparatus Mitochondria Secretory granules Alkaline phosphatase