Dr. Shahzadi Tayyaba Hashmi HISTOLOGY OF DENTINE Dr. Shahzadi Tayyaba Hashmi shahzadi@inaya.edu.sa

INTRODUCTION Avascular Forms the bulk of each tooth crown & root Cellular (contains odontoblast processes ) some capacity for repair by deposition on its pulpal surface

PHYSICAL PROPERTIES OF DENTINE Harder than bone & cementum Softer than enamel Less resistant to attrition (occlusal and incisal attrition) Less resistant to abrasion (toothbrush & other abrasion) Less resistant to acid attack (Caries and Erosion)

HISTOLOGICAL FEATURES OF DENTINE Primary dentin: The most prominent dentin in the tooth, lies between the enamel and the pulp chamber Secondary dentin : Is formed after root formation is complete, normally after the tooth has erupted and is functional. It grows much slower than primary dentin. The growth of this type of dentin causes the decrease in the size of the pulp chamber with age; this is why cavity preparation in young patients is risky which may lead to exposing the pulp

HISTOLOGICAL FEATURES OF DENTINE Tertiary dentin : Is a dentin that formed as a reaction to external insult such as caries. The dentin is formed from a pre-existing odontoblast Tertiary dentin formation is regarded as an important defense mechanism of the pulp-dentin complex in response to either pathological or physiological insults. The presence of tertiary dentin reduces dentin permeability

TERTIARY DENTINE

TYPES OF DENTINE Circumpulpal dentin: The layer of dentin around the outer pulpal wall Peritubular dentin: Dentin that creates the wall of the dentinal tubules Intertubular dentin: Located between the dentinal tubules Interglobular dentin: Areas of hypo mineralized dentine Granular layer of tome's: The superficial layer of dentin , adjacent to cementum, shows minute black spaces in the ground sections These are only found in the root dentin

Dentin structure Dentinoenamel junction Interglobular dentine Dentinal tubules

COMPOSITION OF DENTINE It consists of 35% organic material and 65% inorganic material The organic material consists of collagen fibrils and ground substance( mucopolysaccharides ) The inorganic component consists of hydroxyapatite crystals composed of several thousands of unit cells

ODONTOBLASTIC PROCESSES Odontoblasts: An odontoblast is a biological cell of neural crest origin that is part of the outer surface of the dental pulp, and whose biological function is Dentinogenesis, which is the creation of dentin Odontoblasts are large columnar cells arranged in a well defined layer , sending their odontoblastic process through dentin Each odontoblast sends one odontoblastic process that run inside the dentinal tubule, where both traverse the dentin thickness

ODONTOBLASTS PROCESS

DENTINAL TUBULES Dentinal tubules are structures that span the entire thickness of dentin and form as a result of the mechanism of dentin formation From the outer surface of the dentin to the area nearest the pulp, these tubules follow an S-shaped path The diameter and density of the tubules are greatest near the pulp Within the tubules, there is an odontoblast process

Peritubular dentine Dentinal tubules Intertubular dentine

Thank you