Full details about dentin covered

1. DENTIN
Presented By : Dr. Yashkumar R Shah
Guided By : Dr. Vijaykumar Shiraguppi

2. CONTENTS
 Introduction
 Physical Properties and Chemical Composition
 Dentinogenesis
 Structure of Dentin
 Types of Dentin
 Age and Functional Changes
 Innervation of Dentin
 Clinical Considerations
 Developmental Anomalies
 Conclusion

3. INTRODUCTION
 1771– John Hunter Hard Tissue
 1775– Anton Von Leewonhoek Described Tubular Structures
 1891– Von Ebner gave the term Ebner’s Growth Lines
 1906– Von Korff gave the term Korff’s Fibres
 Hard Tissue of the Tooth
 Provides bulk to the tooth
 Surrounds central core of nerves and blood vessels of pulp

4. PHYSICAL PROPERTIES
PROPERTY VALUE
Color Pale Yellow-- White
Thickness 3-10 mm
Modulus Of Elasticity 15-20 GPa
Hardness 68 KHN
Carious Dentin 25 KHN
Sclerotic Dentin 80 KHN
Compressive Strength 266 MPa
Tensile Strength 50 MPa
Proportional Limit 148 MPa
Radiopacity Less than Enamel

5. CHEMICAL COMPOSITION
INORGANIC,
65%
ORGANIC,
20%
WATER 15%
BY WEIGHT
INORGANIC ORGANIC WATER
45%
33%
22%
BY VOLUME
INORGANIC ORGANIC WATER

6. ORGANIC SUBSTANCES
 Collagen– 82% Mainly type 1
 Non Collagenous Matrix Proteins– 18%
Phosphoproteins– DPP
Glycoproteins– Dentin Sialoprotein , Osteocalcin
( seen in mineralized matrix )
Proteoglycans– chondroitin sulphate in Predentin
 Enzymes– Acid phosphatase, Alkaline phosphatase
 Phospholipids and Glycolipids in traces.
INORGANIC SUBSTANCES
Hydroxyapatite
Calcium phosphate and carbonate
Trace elements like Cu, Fe, F, Zn

7. DENTINOGENESIS
 First formed hard tissue
 Dentin formation precedes enamel
 Advanced Bell Stage
 Future Cusps tips and Proceeds apically
 STAGES OF FORMATION
1) Synthesis of Organic substances
2) Subsequent Mineralization
Carried Out by– ODONTOBLASTS
PATTERNS OF MINERALIZATION
1) Globular( Calcospheric )
2) Linear

8. ODONTOBLASTS DIFFERENTIATION
 Odontoblasts – cells of the pulp
 Mesenchymal in origin
 Lie along the dental papilla– adjacent to IEE
 Undifferentiated ectomsenchymal cells of the dental papilla divide
 Mitosis
 Form Daughter cells
 Diffrentiation occurs

9. PATTERNS OF MINERALIZATION
 Globular mineralization
Continued crystal growth radial pattern globular masses fuse to form
large masses
 Deposition of HA crystals in discrete areas at any one time
 Mantle Dentin
 Linear mineralization
 Rate of dentin formation occurs slowly mineralization appears uniform
 Circumpulpal Dentin
GLOBULAR LINEAR

10. ROOT DENTIN FORMATION
 Begins once enamel and dentin formation reaches the future DEJ
 Initiated by the cells of HERS which induce the odontoblast differentiation
 Less mineralized and has less no of tubules
 Completes – 18 months after the eruption of primary teeth
2-3 years after the eruption of the permanent teeth

11. STRUCTURES
 Dentinal tubules
 Odontoblastic processes
 Predentin ( Non Mineralized matrix )
 Intertubular dentin
 Peritubular dentin

12. DENTINAL TUBULES
 Most Striking feature
 S shaped course
 Perpendicular to the DEJ
 Convexity toward the apex
 Tubules are closely packed near the pulp and are apart in peripheral layer
 Diameter of tubules is more near the pulp
 Primary and secondary curvatures
 Tubule density/ unit area decreases from pulp
towards the outer surface in the ratio 4 : 1

13. BRANCHES OF DENTINAL TUBULES
 Terminal branches
 Lateral branches(canaliculi or microtubules)
 Diameter of tubule near pulp– 3-4 micrometre
 Diameter of dentinal tubules near periphery– 1 micrometre
 No of tubules per unit area--- crown > root

14. PREDENTIN
 First formed dentin
 Non mineralized
 Adjacent to pulp
 2-6 um wide
 Gradually mineralizes
 Thickness remains constant
 Stains less intensely

15. PERITUBULAR DENTIN
 Immediately surrounds the dentinal tubules
 More mineralized than intertubular dentin
 Increased calcified matrix surrounds the dentinal tubules
 Lost in decalcified sections

16. INTERTUBULAR DENTIN
 Main body of the dentin
 Primary secretory product
 Less mineralized than peritubular dentin
 Matrix retains after decalcification
 Located between the dentinal tubules or between the zones of peritubular
dentin

17. LAMINA LIMITANS
 Calcified tubule wall has an inner organic lining
 Intimate contact with the odontoblastic process
 Sheath of neuman
 High in glycosaminoglycans
 Seen in electron microscope

18. INTERGLOBULAR DENTIN
 Mineralization of dentin begins in a small globular area
 Fail to coalesce into homogenous mass
 Zone of hypomineralization between the globules
 Forms in circumpulpal dentin just below the mantle dentin
 Dentinal tubules pass uninterrupted
 Cervical and middle thirds of the crown
 Cervical third of the root

19. ODONTOBLASTIC PROCESSES
 Cytoplasmic extensions of the odontoblasts
 Largest in diameter near the pulp(3-4µm) and 1µm(dentin)
 Enamel spindles
 Odontoblastic processes narrow to about half of the
size of the cell when they enter the tubules

20. INCREMENTAL LINES
 Reflect the daily deposition of dentin
 Incremental lines of von Ebner
 Right angle to the dentinal tubules
 Distance between the lines in crown– 4-8µm
less in root
 5 day increment pattern– lines apart 20µm

21. CONTOUR LINES OF OWEN
 Accentuated incremental lines
 Disturbance in matrix formation and mineralization process
 Hypomineralized areas
 Periods of illnesses and adequate nutrition
 Coincidence of secondary curvatures

22. TOMES GRANULAR LAYER
 In ground sections of root dentin granular zone
 Zone adjacent to the cementum
 Looping or coalescing of the dentinal tubules
 Increases in amount from CEJ to apex
 Remains unmineralized

23. DENTINOENAMEL JUNCTION
 First hard tissue interface to develop
 Scalloped with convexity towards the dentin
 Scalloping greatest in the cuspal area– occlusal stresses are more
 Branching of the odontoblastic processes present– increased sensitivity

24. TYPES OF DENTIN
 Primary dentin
Mantle dentin
Circumpulpal dentin
 Secondary dentin
 Tertiary dentin

25. PRIMARY DENTIN
( PRIOR TO ROOT COMPLETION )
Mantle Circumpulpal
Location Below DEJ B/n Mantle and Predentin
Thickness 20µ 68mm
Mineralization Less More
Defects Less More
Collagen Fibrils Larger- 0.1-0.2 µ
Perpendicular to DEJ
Smaller- 0.02-0.05µ
Parallel to DEJ closely
packed

26. SECONDARY DENTIN
 Formed after root completion
 Bordering the pulp
 Fewer tubules than the primary dentin
 Bend in tubules – interface of primary and secondary dentin
 Deposited more slowly
 Formed in greater amounts – roof of pulp chamber protecting the pulp horns

27. TERTIARY DENTIN
 Localized formation of dentin at the pulp dentin border in response to noxious
stimuli—
 Caries , trauma, attrition etc.
 No continuity with the primary or secondary dentin--- decreased permeability
 Quality of formation depends upon– intensity of stimulus, vitality of pulp
 Also known as
 reparative dentin
 defence dentin
 reactive dentin
 irritational dentin
 replacement dentin
 adventitious dentin

28. TERTIARY DENTIN
Reactionary dentin Reparative dentin
Stimulus for formation Mild Aggressive
Formative cells Surviving post mitotic
odontoblasts
New odontoblasts like
cells from progenitors
Structure Physiologic dentin change
in the direction of
dentinal tubules
Heterogenous
Tubular( organised )
Osteodentin
Fibrodentin
(disorganised )

29. AGE CHANGES IN THE DENTIN
 Increase in the thickness of dentin
 Increased sclerosis of dentinal tubules
 Decreased amount of the dentinal fluid
 Reduced permeability
 Pathological effects
Dead tracts
Sclerotic or transparent dentin

30. DEAD TRACTS
 Dried ground section of normal dentin
 Odontoblastic processes degenerated
 Empty tubules filled with air
 Black in transmitted light
 White in reflected light
 Area demonstrates decreased sensitivity

31. SCLEROTIC OR TRANSPARENT DENTIN
 Protective changes in the existing dentin
 Trauma , caries, attrition
 Deposition of apatite crystals and collagen in dentinal tubules
 Blocking of tubules
 Defensive action
 Reduced permeability
 Mineral density greater
 Prolongs the pulp vitality
 Elderly people– mostly in roots

32. PAIN TRANSMISSION THEORIES
 Direct neural stimulation theory
 Transduction theory
 Hydrodynamic theory( most popular theory )

33. DENTINAL HYPERSENSITIVITY
 Unusual symptom of the pulp dentin complex
 Short sharp pain
 Exposed dentin
 Enamel attrition, erosion
 Loss of cementum due to recession, scaling, refractory periodontitis
 Best explained by hydrodynamic theory

34. MANAGEMENT
 At home desensitizing therapy
 In office desensitizing therapy
 Fluorides
 Oxalates
 Adhesive materials
 Bioglass
 Laser
 Casein phoshopeptide- amorphous calcium phosphate
S. MIGLANI, JOURNAL OF CONSERVATIVE DENTISTRY OCT-DEC-2010 VOL 13
..

35. CLINICAL CONSIDERATIONS
 Exposure of dentinal tubules– fracture, caries, attrition, cavity preparation
 They should not be insulted
 Sealed by varnishes or restorations
 Pulp protection from thermal damage --- bases below the restoration
 Chemical protection from liners and varnishes
 Cavity floor– dentin
 Dentin is resilient – absorbs and resists forces of mastication and deformation--- grips
the restorative material
 Grooves , coves , pins completely in dentin

36. REMAINING DENTIN THICKNESS(RDT)
 Stanley et al- RDT should be at least 2mm to protect the pulp
 Smart bur-2 self limiting caries removal bur
 0.5mm- 75% 1mm- 90%
 Maximal reparative dentin was present when RDT was between 0.25-0.5mm

37. OPERATIVE INSTRUMENTATION
 Treated with care during instrumentation to prevent damage to odontoblasts
 AVOID
Excessive cutting
Heat generation
Continuous drying– dislodgement aspiration into tubules
 USE
Air water coolant
Sharp hand instruments – most suitable
Tungsten carbide burs to cut vital dentin– less heat generation

38. VITAL PULP THERAPY
 Reparative dentin formation can be stimulated by cavity lining materials
(calcium hydroxide)
 Includes direct and indirect pulp capping
 Dentinal bridge forms over the pulpal tissue
 Signs of healing

39. BONDING TO DENTIN
 Challenge
 Dentin is both hydrophilic and hydrophobic
 Increase organic content, tubular nature, dentinal fluid
 Further complicated by smear layer– dentin abraded surfaces
 It decreases the permeability but interferes with bonding so it must be removed
 Smear layer ( denatured collagen , HA crystals debris( 1-4 µm thick)

40. ENDODONTICS
 Secondary dentin and tertiary dentin obliteration of pulp
chamber and root canals
 Endodontic treatment – difficult
 Periapical surgery– root resection closer to 90º to minimize the
no. of exposed dentinal tubules
 Strip perforation and vertical root fractures

41. CONCLUSION
 There is no substitute for dentin
 It is the main hard tissue which exhibits different properties which should be
taken care of during different procedures
 We should always try to preserve the remaining dentin thickness during cavity
preparation as it provides protection to the pulp

42. REFERENCES
 Orban’s – ORAL HISTOLOGYAND EMBRYOLOGY 13th Edition
 Ten Cate’s – ORAL HISTOLOGY 8th edition
 M.A Marzouk Operative dentistry