1. CEMENTUM

2. INTRODUCTION Cementum is a specialised hard layer of calcified mesenchymal tissues which forms the outer covering of the anatomical root. It is also called as Substantia Ossea Cementum is the part of Periodontium . Human Cementum is avascular & has no innervation.

7. CEMENTOGENESIS : Cementum develops from the activity of mesenchymal cells of dental follicle after fragmentation of the epithelial root sheath. After formation of dentin, loss of continuity occurs in the epithelial root sheath. This allows adjacent cells of the investing layer of the dental follicle to come to lie on surface of root dentin & these are induced to differntiate into cementoblasts. CEMENTOENAMEL JUNCTION : The interface between the Cementum & Enamel at the cervical region of tooth is known as cementoenamel junction. It is of 3 types

8. Pattern I : Pattern Pattern III : Overlapping Type (60%) Butt joint (30%) Gap joint (10%) CEMENTODENTINAL JUNCTION It is interface between the dentin & cementum. Scalloped in deciduous teeth & smooth in the permanent teeth. FUNCTIONS OF CEMENTUM :  Cementum provide a medium for the attachment to the collagen fibers of periodontal ligament.  Cementum is hard & has no blood supply, It does not show resorption under masticatory or orthodontic forces. Thus, during heavy orthodontic forces, tooth integrity is maintained & alveolar bone being elastic in nature changes its shape, fulfilling the orthodontic requirement.  Cementum has property of continuous deposition & does the patch work or repair for the damage such as fracture or resorption of tooth surface.  Regular Cementum deposition at the root apex, helps to replenish the lost tooth height due to occlusal wear or helps in passive eruption of teeth.

13. AGING OF CEMENTUM :  Surface become rough.  Cemental Resorption.  Permeability Decreases.  More Cemental deposition may lead to closure of the apical foramen.

14. CLINICAL CONSIDERATION : I. Ankylosis : Fusion of cementum & alveolar bone with no PDL in between, known as Ankylosis. Causes : Causes :   Faulty replantation & transplantation of teeth.  Embedded teeth.  Chronic Periapical Infection.  Trauma to deciduous teeth. II. Importance of Root Planing in Periodontal Treatment. Root planing is a treatment to remove necrotic cementum & smoothening the root surface in order to reduce the pocket depth