are specialized connective tissues of mesodermal origin, formed from the dental papilla of the tooth bud

• Forms the largest portion of tooth structure. • Normally, yellow white slightly darker the enamel

Externally,It is covered by enamel on the anatomical crown and by cementum on the anatomical root.

• Internally, ___ forms the wall of the pulp cavity (PULP CHAMBER AND PULP CANAL)

Provides the bulk and general form of tooth. 2. Determines the shape of the crown. 3. Protection of the brittle enamel

4 odontogenesis

1. Ectomesenchymal cells elongate 2. Organelles increase in the cells 3. Odontoblastic process appears

ectomensenchymal cells proliferate

PREDENTIN FORMATION 1. COLLAGEN protein synthesis in rER of odontoblasts 2. The proteins are packaged into vesicles in golgi complex 3. Vesicles migrate to the area of odotoblastic process 4. Release of secreted protein outside the cell through exocytosis

GLOBULAR AND LINEAR CALCIFICATION

1. HA in Globules or calcospherules 2. Globules expand and fuse together

Crystals are deposited in linear direction

or imbrication lines, appear as fine lines or striations in dentin. - run at right angles to the dentinal tubules.

These lines reflect the 5-day rhythmic, recurrent deposition of dentin matrix as well as hesitation in the daily formative process (20 microns)

INCREMENTAL LINES OF RETZIUS

INCREMENTAL LINES OF VON EBNER

MARKS THE APPOSITIONAL GROWTH OF ENAMEL AND DENTIN

hypomineralization between the globules.

Forms in crowns of teeth in the circumpulpal dentin j

The dentinal tubules pass u n i n t e r r u p t e d l y , t h u s demonstrating a defect of mineralization & not of matrix formation

Some of the incremental lines are accentuated because of disturbances in the matrix and mineralization process.

continues after tooth eruption and throughout the life of the pulp.

begins at areas subjacent to the cusp tip or incisal ridge and gradually spreads to the apex of the root.

yellowish elastic lower content of mineral salts - more radiolucent

Inrganic matter: HYDROXYAPATITE CRYSTALS Ca10(PO4)6(OH)2

Organic and water percentage Form the pulp tissue Exudate. imparts elasticity to dentin

Organic matters and water COLLAGEN Non-collagenous Proteins GROUND SUBSTANCE: Mucopolysaccharides (proteoglycans, GAGs)

Unmineralized zone of dentin. The most recently formed layer of dentin is always on the pulpal surface.

This unmineralized zone of dentin is immediately next to the cell bodies of odontoblasts

Composed primarily of collagen fibers and water.

Dentin forming the initial shape of the tooth

Usually completed after 3 years after tooth erruption.

represents all the dentin that is formed before the completion of root formation

first formed dentin in the crown underlying the dentinoenamel junction. outer or most peripheral part of the primary dentin & is about 20um thick.

forms the remaining primary dentin or bulk of the tooth. Represents all of the dentin formed prior to root completion. fibrils are much smaller in diameter & are more closely packed together. Slightly more mineral content than mantle dentin.

narrow band of dentin bordering the pulp and representing the dentin formed after root completion. fewer tubules

Replaced by odontoblast (termed secondary odontoblast)

Response to moderate-level irritants such as attrition, abrasion, erosion and trauma

appears as a localized dentin on the wall surface of pulp cavity.

small canals that extend through the entire width of dentin, from the pulp to the DEJ

opened and widened by acid application

It is the cytoplasmic cell process (Tomes fiber) of an odontoblast.

cell bodies of odontoblasts are in the pulp near the dentin- pulp border

the dental lymph or fluid of dentin transudate of extracellular fluid, mainly cytoplasm of odontoblastic processes, from the dental pulp via the dentinal tubules.

more highly mineralized than intertubular dentin.

twice as thick in outer dentin (approx. 0.75um) than in inner dentin (0.4um).

Organic matrix is lost along with mineral after decalcification.The calcified tubule wall has an inner organic lining termed the lamina limitans, high in glucosaminoglycans (GAG)

main body of dentin.

located between the dentinal tubules or, more specifically, between the zones of peritubular dentin. Its organic matrix is retained after decalcification

About one-half of its volume is organic matrix, specifically collagen fibers. The fibrils range from 0.5 to 0.2um in diameter.

Can be seen radiographically into the form of radioopaque area in the s-shape tubule.

harder, denser, less sensitive, and more protective of the pulp against subsequent irritations.

Sclerosis resulting from aging

sclerosis resulting from a mild irritation

Dentinal tubules with debris.

greatly reduce permeability of cut dentin surface

Thin altered surface wherever the dentin has been cut or abraded

Few microleakage in thickness and is composed of denatured collagen, hydroxyapatite and other cutting debris

Destruction of exposed collagen

in which stimuli directly effect the nerve endings in the tubules.

membrane of the odontoblast process conducts an impulse to the nerve endings in the predentin, odontoblast zone, and pulp

stimuli cause an inward or outward movement of fluid in the tubule, which in turn produces movement of the odontoblast and its processes.

Referring to the outward (exposed) porton of reactive sclerotic dentin where slow caries has destroyed formerly overlying tooth structure , leaving a hard darkened surface.

It is encountered whenever odontoblast and their processes are stimulated during operative procedures

Is primarily dependent on the remaining dentin thickness and the diameter of tubules.

is less effective barrier than is superficial dentin near the dentino enamel junction and dentinocemental junction

Dissolution of hydroxyapatite crystals

Caries formation is a two-step process;

Dentin demineralizes at

remineralization of demineralized dentin relies on intergrity of collagen framework.

dentin softer than enamel.

dentin is opaque or dull, less reflective to light than similar enamel which appear shiny

in explorer tip, enamel surface provide sharper , and higher pitch sound than dentin surface

have acidic “conditioners” that remove smear layer and partially demineralized the intertubular dentin.

HYBRID LAYER Most dentin bonding system remove or stabilize smear layer allowing to penetrate.

Resultant resin interdiffusion zone.

PERITUBULAR DENTIN calcified tubule wall has an inner organic lining termed the

fibrils found in this zone are perpendicular to the dentinoenamel junction