W8 Dentine Flashcards
What are the physical properties of dentine?
Pale yellow. Harder than bone and cementum but softer than enamel. Higher degree of tensile and flexural strength than enamel
What are the chemical properites by volume of dentine?
By volume Inorganic 50%
Organic 30%
Water 20%
Is enamel Vascular or Avascular?
Avascular
What are the chemical properties of dentin?
Inorganic: hydroxyapatite
Organic: collagen fibres, ground sustance, collaen I, III, IV
What are the chemical properties of organic dentine?
Proteins, dentine phosphoproeins, proteoglycans, lipids
What are dentine tubules?
Run from pulpal surface to DEJ. Segmoid primary curvatures (S shape). Peritubular and intertubular dentine. Secondary curvatures form called contour lines of Owen when they conicide in ajacent tubules.
Where and what types of dentin curvatures can be found?
Granular layer of Tomes found in root, when dentine tubules are in the crown they are called Contour lines of Oen
What is Peritubular Dentine?
The zone of dentine forming the wall of dentine tubules, has 9-15 % higher mineral content than intertubular dentine, smaller crystals than intra.
What are the Odontoblast & processes?
Elongates as the odontoblast moves toward pulp, stimulates differentiation of ameloblasts
What is primary dentine?
Formed prior to eruption, depositied at DEJ and contain incremental lines. Out layer is mantle dentine. Circumpulpal dentine, globular dentine, peritubular and intertuular form in this zone
What classification of dentine?
primary, secondary,
teritary
What is Secondary Dentine?
Formed after the completion of root formation, same as circumpulpal. Scattered more slowly than primary dentine.
What is tertiary dentine?
Forms if dentine is subjected to trauma, irritation, caries into dentine, traumatic cavity prep
What is reactionary dentine?
Dentine foriming in response to an insult existing cells recover.
What is reparative dentine?
Dentine forming in response to an insult, original odontoblasts destroyed and produced calcifed tissue
What are the layers of dentine in the crown?
Mantle, Interglobular, circumpulpal
What are the layers of dentine are in the root?
Hyaline layer, granular of Tomes, Circumpulpal dentine
What is mantle dentine?
Depositied along DEJ. Secreted by immature odontoblasts. Mineralised by matrix vesticles
What is Circumpulpal dentine?
Layer of dentine found around the outer pulpal wall, makes bulk of tooth. Formd and matured after mantle dentine. In the crown it is beneath mantle and interglobular dentine
In the root it is beneath the granular layer of TOmes
What is globular dentine?
Layer between mantle and circumpulpal, found in the coronal portion, May contain interglobual spaces.
What is peritubular?
Immediately surrounds dintinal tubule, high mineral content and lacks collagenous matrix
What is Intertubular
Forms bulk of dentine, around dentinal tubules of crown and root, and is less mineralised
What is the Hyaline layer?
Most peripheral layer of initially unmineralised dentine, aids cementum in binding to dentine. Sits betwwen Cementun and Tomes granular layer
What is the Granular layer of Tomes?
In the root beneath the hyaline layer and cementum
What is predentine?
The innermost layer of dentine. Non mineralise. Composed of collagen and proteoglycans
What is translucent dentine?
Forms with aging due to tubule occlusion by peritubular dentine, pronouced at the root apex.
What is sclerotic dentine?
Tubular occlusion by stimulus, tubules are completely obliterated
What are dead tracts?
Odontoblastic processes killed by a stimulus, empty tubules.
What factors prevent bacteria from invading dentine tubules?
Outward dentinal fluids contains immunoglobulin. Presenses of intratubular deposits of mineral, large collagen fibrils
What are Lines of Von Ebner?
Cross striations across dentinal tubules - thick and thin segments
What are Contour lines of Owen?
As dentine mineralises it follows a patter, DEJ meet the accompanying striae of Retzius that was formed at the same time
What structural lines are associated with primary curvatures?
Sigmoid curvatures called Schreger lines
What structural lines are associated with secondary curvatures?
Contour lines of Owen
What structural lines are associated with Incremental lines?
Short period; Von Ebner lines
Exaggerated line- neonatal
What is coronal pulp?
Occupies crown of tooth, larger than root pulp and different structure + pulp horns
What is radicular pulp?
Extends from cervical regions to apex of tooth.
What is the Apical Foramina and Accessory canals
Opening of toot pulp into periodontium.
What is pulp?
Soft specialised connected tissue, rich and scularised and innervated
What is the role of the pulp?
Induction: interacts with oral epithelium to initiate tooth formation.
Formative: odontoblast from dentine
Caries o2 highly vasuclar.
What is the composition of dental pulp?
Loose CT. Type I collagen fibres, ground substance, mesenchymal cells, neurons
What is the histological organisation?
Odontogenic zone, odontoblast layer, cell free zone, cell rich zone, central pulp
What are some pulp cell types?
Odontoblasts, fibroblasts, scwann cells, endothelial cells
