Cementum
Types
| Cementum Type | Primary Location on Root | Development Time | Key Histological Features | High-Yield MCQ Triggers |
| Acellular Afibrillar Cementum (AAC) | Limited to the Cervical margin (CEJ) area of the tooth. | Formed before tooth eruption. | * Contains neither cells (cementocytes) nor collagen fibers (intrinsic/extrinsic). * A product of ameloblasts rather than cementoblasts. | * "No cells, no fibers" * Plays no role in tooth attachment. * Often covers cervical enamel during development. |
| Acellular Extrinsic Fiber Cementum (AEFC) | Covers the cervical 1/3 to 1/2 of the root. | Formed during tooth eruption and development. | * Contains NO cells. * Packed with Sharpey’s fibers (extrinsic collagen fibers from the periodontal ligament). | * The primary tissue of tooth attachment (anchors the tooth to the alveolar bone). * Forms slowly and very predictably. |
| Cellular Intrinsic Fiber Cementum (CIFC) | Found in resorption bays or areas undergoing repair. | Formed after eruption (secondary cementum). | * Contains cementocytes housed in lacunae. * Contains only intrinsic fibers (made by cementoblasts, not the PDL). | * "Repair cementum". * Plays almost no role in tooth attachment because it lacks Sharpey's fibers. |
| Cellular Mixed Stratified Cementum (CMSC) | Covers the apical 1/3 of the root and the furcation areas. | Formed after the tooth reaches occlusion (functional stage). | * Contains cementocytes. * A complex, layered mix of both intrinsic fibers and extrinsic Sharpey's fibers. | * Compensatory cementum". * Deposited at the apex to compensate for occlusal wear/attrition * Fast-forming, thickest layer of cementum. |