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Dentin
- 2. Introduction • Dentin isthe mineralized hard tissue forming the main bulk of the tooth. • Covered by - Enamel in Crown - Cementum in Root
- 3. Physical Properties • Itis light yellowish in color, becoming darker with age. • Viscoelastic Material (Harder than bone but softer than enamel) • Lower content of mineral salts in dentin renders it more radiolucent than enamel
- 4. Chemical Properties 70 % 30% OrganicMatter + Water substance consists of collagenous fibrils and a ground substance of mucopolysaccharides (proteoglycans and glycos aminoglycans Inorganic Matter consists of hydroxyapetite as in bone, cementum & enamel
- 6. Dentinal Tubules • Extendfrom DEJ to Pulp (entire Dentin thickness) • starting at right angle to pulp • End perpendicular to DEJ and DCJ
- 7. Curvatures Of DentinalTubules 1- Primary Curvature 2- Secondary Curvature
- 8. Dentinal Tubules Primary Curvatures •‘S’ shaped curve. (Sigmoid curvatures) • More prominent in crown • Straight at - cusp tips - incisal edge
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- 12. Content Of DentinalTubules Dental lymph
- 13. Content Of DentinalTubules
- 14. A, Dentinal tubule;B, DEJ; C, Enamel; D, Enamel spindle
- 15. Each cell givesrise to one process, which traverses the predentin & calcified dentin within one tubule
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- 18. Types Of Dentin •According to : 1- Defect uniform in structure 2- Ultra Structure 3- Age Change
- 19. According to defectuniform in structure Tome s Granular layer Interglobular Dentin Root Crown Looping of Dentinal Tubules hypomineralized islands within the Dentin formed due to failure of fusion of mineral globules Small Large Ground Sec only Ground Sec. & Decalcified sec
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- 21. Tome s Granularlayer
- 22. According to UltraStructure IntertubularDentin Peritubular Dentin Between D.T Wall Of D.T Less in Hardness High in Hardness Form main bulk of dentin
- 25. T.S. In DentinalTubules
- 26. INCREMENTAL LINES - VonEbner Line - Contour Line of Owen - Neonatal Line
- 27. Von Ebner Line -Fine striations - perpendicular to tubules - Shows the daily deposition of Dentin
- 28. Contour Line ofOwen - Due to the “Co-incidence of secondary curvatures” - Accentuated Von ebnar incremental line - Shows Hypo-mineralized areas
- 31. Neonatal Line -Accentuated Incrementalline - Prenatal and postnatal dentin separated by neonatal line - Primary teeth, permanent first molars - Reflects abrupt change in environment that occurs at Birth.
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- 33. According to AgeChange Primary dentin Secondary physiologic dentin Tertiary dentin or reparative dentin or reactionary dentin or irregular secondary Mantle Dentin Circumpulpal dentin
- 34. Primary Dentin Circumpulpal dentin Mantle Dentin AfterRoot Completion Before Root Completion Form Remaining Primary Dentin (Bulk Of Tooth ) First Formed Dentin layer Most Peripheral part of primary Dentin Contain more mineral Contain Less Mineral
- 35. Secondary Dentin formsafter root formation is complete narrow band of dentin bordering the pulp Contains fewer tubules than primary dentin Less regularty than primary dentin
- 38. Tertiary dentin ReactiveDentin, Reparative Dentin, Irritation Dentin, Replacement Dentin, Defense Dentin Localized formation of Dentin At pulp –Dentin Border in response to noxious stimuli ( Caries, Trauma, Attrition , Cavity Preparation ) No continuity with primary or secondary Dentin so there is decrease in Dentin permeability Tubules may or may not be present
- 41. Sclerotic Dentin Dentinaltubules become occluded with calcified material Blocking of tubules- Defensive reaction. Elderly people – Mostly in Roots Found specially in radicular dentin (apical 3rd). Transparent or light in transmitted Light dark in reflected light Cause : Mild Stimuli
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- 43. Dead tracts CompleteDestruction of Odontoblastic process in the affected area Dark in transmitted Light Transparent or light in reflected light Cause : Sever stimuli A, Dead tract; B, teritary dentin
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