Cementum Oral Histology PDF

CEMENTUM MALINAO, DMD  DEFINITION AND LOCATION CEMENTUM (Substancia Ossea) Calcified mesodermal tissue forming the external covering of the anatomical roots of the teeth A modified bone covering the root (similar to compact bone) Physiochemical properties, functions, and...

CEMENTUM MALINAO, DMD  DEFINITION AND LOCATION CEMENTUM (Substancia Ossea) Calcified mesodermal tissue forming the external covering of the anatomical roots of the teeth A modified bone covering the root (similar to compact bone) Physiochemical properties, functions, and structures are closely allied to bone  FUNCTIONS 1. Serves to attach the root of the tooth to the alveolar bone by means of fibers of PDL 2. To compensate by its growth for the loss tooth substance due to occlusal wear 3. Contributes to the continuous vertical eruption of teeth 4. Regulates the periodontal space (as bone absorbs) 5. Protects the root dentin 6. Repairs resorbed part of cementum surface, fractured roots and provides new surface for reattachment of broken periodontal fibers  PHYSICAL CHARACTERISTICS 1. Cementum is light yellowish in color, lighter than dentin 2. It is softer than enamel and dentin 3. It lacks luster and has a darker hue 4. It is permeable  CHEMICAL CHARACTERISTICS 45-50% inorganic substance 50-55% organic substance and water Hydroxyapatite – chief inorganic substance Collagen & mucopolysaccharide – chief organic substance  MORPHOLOGIC TYPES OF CEMENTUM ACELLULAR CEMENTUM - clear layer of cementum without cells; lying on top of granular layers of Tomes - sometimes missing on the apical third of the root - (structural composition) Fibers (collagen & Sharpey’s fibers) & calcified ground substance CELULAR CEEMNTUM - layer of cementum with cells - always thickest at the apex  HISTOLOGICAL ELEMENTS OF CEMENTUM CEMENTUM MATRIX – consists of collagen fibril from the dental sac used in formation of the matrix, and cementing ground substance. - Lines of Salter – incremental lines SHARPEY’S FIBERS – fibers of periodontal ligament embedded in the matrix of cementum  HISTOLOGICAL ELEMENTS OF CEMENTUM CEMENTOCYTES (cementum corpuscles) - cementoblasts embedded in the cementum matrix LACUNA & CANALICULI – spaces within the matrix which house the cell bodies of cementocytes are lacunae & the elongated tiny spaces housing the processes are the canaliculi  NUTRITION AND VITALITY Depends on periodontal ligament for the supply of nutrition Shown sometimes by the direction of the canaliculi which are towards the PDL PDL vital = cementum vital  CEMENTO-DENTINAL JUNCTION Generally smooth Temporary teeth – wavy or scalloped Intermediate cementum – layer of tissue found between the cementum and dentin, which does not resemble dentin or cementum in characteristics SPATIAL RELATIONSHIP OF CEMENTUM AND ENAMEL 1. In 60-65 %, the cementum overlaps the cervical end of the enamel 2. In 30%, the cervical end of the cementum meets the cervical end of the enamel 3. In 5-10%, it represents the varieties of relationships, the most common of which is the failure of enamel and cementum to meet, exposing a part of the cervical dentin  CEMENTOGENESIS Process of development of cementum 2 phases in development of cementum 1) Formation of the uncalcified cementum matrix known as cementoid tissue 2) Maturation phases, which involves the transformation of cementoid into calcified cementum  LAB ACTIVITY 1. DRAW AND LABEL THE ACELLULAR CEMENTUM 2. DRAW AND LABEL THE CELLULAR CEMENTUM 3. DRAW THE CEMENTUM MATRIX 4. DRAW THE SHARPEY’S FIBERS 5. DRAW THE LACUNA AND CANALICULI