1. 1
GOOD MORNING!!!
DR.RINKU SHANKLESHA
DEPARTMENT OF CONSERVATIVE DENISTRY
AND ENDODONTICS.
KVGDC, SULLIA

2. Dentin
1

3. CONTENTS
 Introduction
 History
 Development (Dentinogenesis)
 Physical Properties
 Chemical Composition
 Structure of Dentin
 Types Of Dentin
 Age and functional changes
 Innervation of Dentin
 Clinical considerations
 Developmental anomalies
 conclusion
3

4. HISTORY
• 1771 – John Hunter →hard tissue.
• 1775 – Anton Von Leeuwenhoek: Described tubular structures.
• 1837 -Purkinje and Retzius explained about Dentinal Tubules.
• Cuvien gave the name “Ivory” to Dentin
• 1867 – Neuman gave the term Neuman’s sheath
• 1891 – Von Ebner gave the term – Ebner’s growth lines or
Imbrication lines .
• 1906 – Von Korff gave the term – Korff’s fibres
4

5. DENTINOGENESIS
• Process of Dentin
formation.
• Dentin-First Formed Dental
Hard Tissue –crown and
roots
• -Formation of Dentin
Precedes Enamel
• Late Bell stage.
• Future cusp tips, Proceeds
Apically. 5
LATE BELL STAGE

6. STAGES
• Formation Of Dentin- similar to bone and
Cementum.
1. Synthesis Of Organic matrix
2. Subsequent Mineralization.
Carried out by- ODONTOBLASTS
6

7. ODONTOBLASTS
• Cells Of Pulp.
• Derived - Dorsal Cranial Neural Crest,
Mesenchymal in origin.
• Lie along Dental papilla- Adjacent to
IEE.
• Tall columnar cells- length 25-40 μm ,
diameter 4-7 μm,
• Development- Initiated by epigenetic
influence of various signalling
molecules produced by Ameloblasts.
•
7

8. 8
ODONTOBLAST BIOLOGY
ECTOMESENCHYMAL CELLS- Undifferentiated, Flattened
Cells with a large Central Nucleus, Sparse Cytoplasm.
PRE-ODONTOBLASTS - small, ovoid cells with a high
nuc :cyt ratio poorly developed organelles.
SECRETORY ODONTOBLASTS. : Tall columnar cells , 40
μm length , 4-7 μm diameter, Large nucleus – with upto 4 nucleoli,
Abundant RER, Golgi apparatus, mitochondria ,secretory
granules- near the process.
TRANSITIONAL ODONTOBLASTS: Narrower, fewer
organelles, autophagic vacuoles

9. AGED ODONTOBLASTS: Reduction in length and cytoplasmic
Organelles, increase in number and size of lysosomes and
phagosomes, decreased secretory capacity, degenerate with age.
9

10. FORMATION OF PRIMARY
DENTIN
Before Dentinogenesis-There
exists an acellular zone b/n the
IEE and Dental Papilla cells -
ground substance laid down by
the subodontoblastic cells.
The Cells of IEE become taller
and start differentiating into
Ameloblasts-polarity of cell
reverses.- Early Bell Stage.
10

11. 11
They induce the differentiation of
odontoblasts, with reversal of
polarity.
Odontoblasts Develop variable no.
of small processes at the formative
end- start depositing Collagen
matrix- Predentin.
This induces the Ameloblasts to
start depositing Enamel matrix.

12. 12
DEPOSITION OF COLLAGEN MATRIX
INITIALLY: large dia Type III
Collagen - 0.1- 0.2μ
VON KORFF’S FIBRES
-Cork Screw Shaped
-Perpendicular to DEJ
-Argyrophillic in nature.
LATER- smaller Fibrils-perpendicular
to Tubules,
parallel To DEJ.

13. 13
As more matrix is formed- the Odontoblast
Migrates centripetally, towards the pulp.
A Single Prominent Process- Odontoblast
Process- (TOME’S FIBRES)- Tubular nature Is
established.
The rate of matrix production - about- 4-
8μ/day for Primary Dentin. And secondary
dentin -1μ/day
MINERALIZATION Begins once matrix is
about 5μ thick.

14. 14
Various Matrix Proteins Influence Mineralization:
• DPP- Binds to Ca, Controls Growth of H.A
Crystals
• Osteonectin- Inhibits growth of H.A crystals,
promotes their Binding to Collagen
• Gla-proteins, Phospholipids- Act as nucleators
to concentrate calcium.
• Proteoglycans- inhibit premature mineralization
seen in predentin.
CALCIFICATION OF MATRIX- initiated by
small crystallites within MatrixVesicles, budded from
odontoblasts.

15. 15
MATRIX VESICLES contain Alkaline Phosphatase
-↑ concentration of phosphates → combine with
Calcium →Hydroxyapatite Crystals.
Crystals- grow rapidly, rupture the matrix vesicles
Spread -clusters of crystallites → fuse with
adjacent clusters to form a continuous layer of
mineralized matrix
.
Initially- on the surface of the collagen fibrils and
ground substance, later within the fibrils- aligned
with collagen.

16. PATTERNS OF MINERALIZATION
• GLOBULAR(CALCOSPHERIC) :Deposition of HA
crystals in several discrete areas of matrix at any one
time.
• Continued crystal growth → globular masses →
enlarge → fuse → single layer of calcified mass.
• MANTLE DENTIN- matrix vesicles.
16
RADIAL CRYSTAL GROWTH INTERGLOBULAR DENTIN

17. 17
LINEAR : When the rate of Dentin
formation occurs Slowly -Mineralization
front appears more Uniform –
CIRCUMPULPAL DENTIN
LINEAR PATTERN

18. ROOT DENTIN FORMATION
• Begins once Enamel& Dentin
formation reaches the future
CEJ.
• Initiated by Cells of HERS-which
induce odontoblast
differentiation.
• Collagen fibres- parallel to CDJ.
• Less mineralized, less no. of
Tubules.
• Complete- 18mths after
eruption-Primary
2-3 yrs -Permanent Teeth 18

19. VASCULAR SUPPLY
• Provided by the Capillaries found in the subodontoblastic
layer of the pulp.
• Migrate between odontoblasts, and later - Regress.
19

20. PHYSICAL AND MECHANICAL
PROPERTIES
PROPERTY VALUE
COLOUR PALE YELLOW- WHITE
THICKNESS 3 - 10mm
MODULUS OF ELASTICITY 15-20GPA
HARDNESS 68 KHN
CARIOUS DENTIN 25 KHN
SCLEROTIC DENTIN 80 KHN
COMPRESSIVE STRENGTH 266 MPa
TENSILE STRENGTH 50 Mpa
PROPORTIONAL LIMIT 148 MPa
RADIOOPACITY LESS THAN ENAMEL 20

21. CHEMICAL COMPOSITION
21
BY VOLUME
45%
22%
33%
BY WEIGHT
20%
15%
65%
INORGANIC ORGANIC WATER

22. ORGANIC COMPONENTS
• Collagen – 82% , MAINLY TYPE I and some amount of Type
III and V.
• Non Collagenous Matrix Proteins- 18%
-Phosphoproteins- DPP(Phosphoryn), Gla-Protein.
-Glycoproteins- Dentin Sialoprotein,Osteonectin, Osteocalcin,
(Seen in mineralized matrix)
- Proteoglycans- Chondroitin SO4 (seen mainly in Predentin)
• Enzymes- Acid Phosphatase, Alkaline Phosphatase.
• Lipids- phospholipids, glycolipids etc. in traces.
22

23. INORGANIC COMPONENTS
• Calcium Hydroxyapatite: CA10(PO4)6(OH)2
• Thin plate like crystals, shorter than enamel.
• 3.5 nm thick, 100 nm long.
• Salts- calcium carbonate, sulphate, phosphate
etc.
• Trace Elements- Cu, Fe, F, Zn
23

24. STRUCTURAL COMPONENTS
• Odontoblast
Process
• Dentinal Tubules
• Non mineralized
matrix- Predentin
• Mineralized matrix-
Peritubular and
Intertubular Dentin.
24

25. DENTINAL TUBULES
• Most Striking Feature.
• From pulp to DEJ
• Occupy 1% superficial and 30%
volume of Deep Dentin.
• Size- varies with location.3-4μm near
pulp,1μ near the DEJ (ratio,5:1))
• Smaller branches- canaliculi (1μm in
dia, 2μm in length)-pathways of
exchange
• 1-2μ apart.
25

26. PRIMARY CURVATURES
CROWN ROOT
26
Tubules exhibit Sigmoid curvatures-More prominent
in crown.
Least pronounced at cusp tips, incisal edges

27. SECONDARY CURVATURES
27
At Increased Magnification- Secondary Curvatures.

28. A. - 50,000 to 90,000 / sqmm
pulpal surface
B. - 30,000 to 35,000/sqmm
middle dentine
C. - 10,000 to 25,000/sqmm
peripheral dentine
28
Tubule density/ unit area - ↑es toward pulp.
No. of Tubules / unit area – crown> root.

29. PERIODONTOBLASTIC SPACE
• Potential space between tubule wall and od.
Process.
• Contents - nerves, collagen fibrils, plasma
proteins, glycoproteins and mitochondria.
• Surface Area Tubule lumina - 1% at DEJ, 22 %
at Pulp(PASCHLEY-1996)
29

30. Lamina Limitans
30
• Organic sheath or membrane lining the Dentinal
tubules
• seen in EM sections.

31. DENTINAL FLUID
( Dentin Lymph)
• Occupies space b/n dentinal tubule and od. Process.
• Ultrafiltrate- pulp Capillaries
• Composition is similar to that of plasma..Ca content in
dentinal fluid of predentin is 2-3 times higher than in plasma.
• Tissue pressure of pulp- 14 cm of H2O, (10.3mm Hg).
(Ciucchi et al 1995) pressure gradient exists between pulp and
oral cavity -tends to flow outwards slowly
• Exposure of Tubules- tooth fracture or cavity prep.-Outward
movement → tiny droplets.-dehydrating the surface-rapid flow
of fluid-sensitivity. 31

32. • Slow outward flow of fluid (0.02nl//sec/mm -1-
1.5.microlitre/sec/mm for nerves to begin firing.
32
•Acts as barrier for microbes and toxins .
•Hydraulic transfer and relief of stresses in Dentin-through
the Periodontium and Enamel.
•Non vital Teeth- More brittle. (Carter et al 1983)

33. PREDENTIN
• First Formed Dentin.
• A layer of Un Mineralized Matrix
• Thickness- 50 μ, 2-6μm wide
• Collagen and Non-collagenous
matrix proteins.
• Gradually Mineralizes.
PREDENTIN
• Thickness Remains Constant.
• Stains less intensely 33

34. PERITUBULAR DENTIN
PERILUMINAL/INTRATUBULAR
. DENTIN
• Dentin that immediately surrounds the dentinal tubules
• Collar - ↑ Calcified Matrix – surrounds Dentinal tubules.
• ↓ collagen fibrils, ↑ sulfated proteoglycans.
• 40% more mineralized than ITD.
• Hardness of H. A. crystals-250 KHN
(Kinney Et al- 1996)
• Thickness-0.75μm- .4μm
• Lost in decalcified Sections, 34

35. INTERTUBULAR DENTIN
• Main Body Of Dentin.
• 10 Secretory Product.
• Less mineralized
• Hardness of H. A
crystals -52KHN
(Kinney et al 1996)
35

36. Dentinal Tubule
Peritubular
Dentin
Intertubular
Dentin
36

37. INTERGLOBULAR DENTIN
• Unmineralized islands within the
Dentin- formed due to failure of
fusion of mineral globules .
• In Circumpulpal Dentin- just
below Mantle Dentin,
• Subjacent to pits and fissures.
• .
• Tubules pass uninterrupted.
• Vitamin ‘D’ deficiency or
Hypophosphatasia
37

38. INCREMENTAL LINES OF VON
EBNER/ IMBRICATION LINES
• Fine striations- perpendicular to
tubules.
• Daily rhythmic deposition of
Dentin-
• 4-8μ apart in crown, closer in root.
• 5 DAY INCREMENT-20μm
38

39. LINES OF SCHREGER
Congruence Of PRIMARY CURVATURES of Dentinal tubules.
39

40. CONTOUR LINES OF OWEN
• “Co-incidence of 2o
curvatures”
• ACCENTUATED
INCREMENTAL LINES
• Disturbance in matrix
formation
• Hypomineralized areas.
• Periods of illness/
inadequate nutrition.
40
GROUND SECTION

41. NEONATAL LINE
• Accentuated Incremental
line
• Primary teeth, permanent
first molars.
• Zone of hypo calcification
• Reflects abrupt change in
environment- At Birth.
• Dentin formed Before birth
-Better Quality
41
ENAMEL
DENTIN

42. GRANULAR LAYER OF TOMES
• Granular zone-
• Ground sections- Root
Dentin in transmitted
light.
• Increases in amt. from
CEJ to Apex.
• Looping /coalescing of
Dent. Tubules.
• Hypomineralized areas.
42

43. DENTINOENAMEL JUNCTION
• First hard Tissue Interface
To Develop
• Scalloped- with convexity
towards Dentin.
• Scalloping greatest in
Cuspal area →Occlusal
stress more
• Branching of Od. Process
here → ↑ed sensitivity.
43

44. ENAMEL SPINDLES
• Odontoblast processes sometimes extend into the Enamel.
• Length is about 10—40 m
• Seen near Incisal edges
& cusp tips
• Appear dark
in ground sections
• Hypomineralized Areas
• Responsible for the Spread of Caries from Enamel to Dentin.
44

45. DENTINO-CEMENTAL
JUNCTION
• Firm Attachment
• Smooth in Permanent teeth,
scalloped in 1o.
• Intermediate Zone- Hyaline layer
Of Hopewell Smith- Cements the
cementum to Dentin.
• Product Of HERS
• Endodontics- Apical Constriction
Termination of Instrumentation. 45

46. TYPES OF DENTIN
• Primary dentin
– Mantle
– Circumpulpal
• Secondary dentin
• Tertiary dentin
46

47. PRIMARY DENTIN
MANTLE CIRCUMPULPAL
LOCATION Below DEJ B/n Mantle Dentin
and Predentin.
THICKNESS 20 μ 68mm
MINERALIZATION ↓ ↑
DEFECTS ↓ ↑
COLLAGEN FIBRES Larger- 0.1-0.2μ
perpendicular to
the DEJ
Smaller- 0.02- 0.05μ
parallel to the DEJ.
Closely packed.
47
(Prior To Root Completion)

48. SECONDARY DENTIN
• Develops after root completion
• Narrow band- bordering the pulp
• Deposited more slowly- 1μ/day.
• Fewer tubules
• Bending of tubules at the 10 &
2° Dentin interface.
• Formed in greater amts.- roof of
pulp chamber- protecting the
pulp horns.
48

49. TERTIARY DENTIN
• Localized formation of Dentin At pulp –Dentin
Border in response to noxious stimuli- Caries,
Trauma Attrition , Cavity Prep. Etc.
Also known as:
 Reactive Dentin,
 Reparative Dentin,
 Irritation Dentin,
 Replacement Dentin,
 Adventitious Dentin,
 Defense Dentin
No continuity with 10 or 20
Dentin so there is ↓ Dentin
permeability.
Quality Depends on :
•Intensity of stimulus.
•Vitality of pulp.
49

50. TERTIARY DENTIN
REACTIONARY DENTIN REPARATIVE DENTIN
STIMULUS FOR
FORMATION
MILD AGGRESSIVE
FORMATIVE CELLS SURVIVING POST MITOTIC
ODONTOBLASTS
NEW ODONTOBLAST- LIKE
CELLS FROM
PROGENITORS
STRUCTURE PHYSIOLOGIC DENTIN
CHANGE IN DIRECTION OF
NEW DENTINAL TUBULES
HETEROGENOUS:
-TUBULAR (ORGANISED)
OSTEODENTIN
FIBRODENTIN
(DISORG)
SMITH ET AL (1994) 50

51. 51
REACTIONARY DENTIN REPARATIVE DENTIN
The avg. daily rate of reparative dentin formation is about 2.8-3 μ/day-acc
to Stanley in 1996.

52. REPARATIVE DENTIN
52

53. AGE AND FUNCTIONAL
CHANGES
• DEAD TRACTS
• DENTIN SCLEROSIS
• REPARATIVE DENTIN
53

54. DEAD TRACTS
• Represent Empty Tubules Filled
with air.
• Due to → Degeneration of
odontoblastic process (caries,
erosion, attrition etc.)
• Ground Sections
• Black in transmitted light, WHITE
IN REFLECTED LIGHT.
• Older Teeth-Areas of narrow
pulp horns. ↓ sensitivity. 54

55. SCLEROTIC DENTIN
• Presence of irritating stimuli -Caries, Attrition, Erosion, Cavity
Preparation → Deposition of Apatite Crystals & Collagen in
Dentinal Tubules.
• Blocking of tubules- Defensive reaction.
• Filled with H. A - Obliteration of Lumen- Peritubular Dentin.
• Refractive indices are equalized- Transparent
• Elderly people – Mostly in Roots
55

56. • Also seen- slowly
progressing Caries.
• Reduced Permeability
• Prolonged pulp vitality
• Resistant to Caries
• Forensic Odontology:One of
the criteria for age
determination using
Gustafson’s method.
56
SCLEROTIC DENTIN

57. EBURNATED DENTIN
• Exposed portion of reactive sclerotic Dentin.
• Slow caries has destroyed overlying tooth
structure .
• hard , darkened , cleanable surface.
• Resistant to further caries Attack.
57

58. REPARATIVE DENTIN
• Formed in response to
trauma, chronic
irritation etc.
• Provides protection to
the underlying pulp- by
Decreasing dentin
permeability.
58

59. INNERVATION OF DENTIN
• Numerous Nerve Endings in
Predentin and Inner Dentin.
• 100-150μm from pulp.
• % of tubules innerveted Near Pulp
Horns –(40%)
• ↓ near CEJ- 1%
• Closely Associated with Odontoblast
Process.
• Arise from myelinated nerve fibers of
Dental Pulp- (Aδ fibres) Reach Brain
via Trigeminal N.
59

60. PAIN TRANSMISSION THROUGH
60
DENTIN
• DIRECT NEURAL STMULATION
• TRANSDUCTION THEORY
• HYDRODYNAMIC THEORY

61. DIRECT NEURAL STIMULATION
• It was proposed by Scott
Stella in 1963
• Nerve endings in Tubules
are Directly Activated by
External Stimuli
• This view rests on the
assumption that Nerve
fibres Extend to DEJ.
• Not accepted
61

62. TRANSDUCTION THEORY
• Odontoblastic Processes are
primary structures excited by
stimulus.
• Transmit impulse to Nerve
Endings
• Supported by evidence that
odontoblasts → Neural Crest
Origin
• Discarded -No synaptic Contacts
or vesicles - b/n odontoblasts and
axons.
62

63. HYDRODYNAMIC THEORY
• Most popular Theory
• Gysi (1900), Brannstrom
• Various stimuli such as Heat,
Cold, Air, Mechanical
Pressure →Movement
of Fluid Within Tubule
↓
• Activating the Free Nerve
Endings Associated with
Odontoblast and its Process
• Act as Mechanoreceptors-
Sensation is felt as pain.
63

64. 64

65. “Hypersensitivity”
• Unusual symptom of Pulp- Dentin Complex.
• Sharp Pain- easily localized.
• Etiology- Exposure of Dentinal tubules
loss of enamel- Attrition, abrasion, erosion etc.
loss of cementum- scaling and RP, Gingival Recession
• Best Explained by the Hydrodynamic Theory.
• Management - Block The Dentinal Tubules!!!
• Desensitising toothpastes-AgNo3, SrCl2, fluorides, Bonding Agents,
lasers etc. 65

66. Dentin Permeability
• Highly Permeable- Tubular Nature
• TRANS DENTINAL- Movement-Through
entire thickness of Dentin- via tubules.
• INTRADENTINAL- Movement of
exogenous subst. into intertubular Dentin.-
seen during bonding.leading to passage of
irritants towards pulp.
• ↓Dentin thickness -↑Dentin permeability.
66

67. 67
MORE PERMEABLE LESS PERMEABLE
DENTIN NEAR PULP
HORNS
DENTIN FURTHER AWAY
AXIAL WALLS OF
CLASS II CAVITY
PULPAL FLOOR OF CLASS
II CAVITY
CORONAL DENTIN ROOT DENTIN
NORMAL DENTIN SCLEROTIC DENTIN

69. CLINICAL CONSIDERATIONS
69

70. “Exposure of Dentinal Tubules”
• Tooth wear, fractures, caries,
cavity cutting procedures etc.
lead to exposure of Dentinal tubules.
• 1 mm of Exposed Dentin → Damage to 30,000 living
odontoblasts.
• Exposed Tubules- Should not be insulted!!
• Sealed- Bonding agents, varnishes or Restorations.
70

71. Pulp protection
• Irritants from Restorative
Materials- Pulpal Damage
• Thermal Protection- Bases
below Restoration
• Chemical Protection- Cavity
liners and varnishes
71

72. Dentinal Caries
• Tubular Nature of Dentin→ Rapid spread of Caries
Through Dentin.
• Lateral spread along DEJ→ Undermined Enamel.
ZONE 1 – Normal dentin
ZONE 2 – Sub transparent
ZONE 3 – Transparent dentin
ZONE 4 – Turbid dentin
ZONE 5 – Infected dentin
72

73. Infected and Affected Dentin
INFECTED DENTIN AFFECTED DENTIN
SOFTENED AND
CONTAMINATED WITH
BACTERIA
SOFTENED ,
DEMINERALISED BUT NOT
YET INVADED BY
BACTERIA
CONTAINS IRREVERSIBLY
DENATURED COLLAGEN –
STAINED BY CARIES
DETECTING DYE .
CONTAINS REVERSIBLY
DENATURED COLLAGEN
REQUIRES REMOVAL DOES NOT REQUIRE
REMOVAL
73

74. Operative Instrumentation
• 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.
74
Dentin- Treated with care during op. instrumentation
to prevent damage to the odontoblasts

75. “Cavity Preparation”
• Cavity Floor → Dentin
• Dentin is RESILIENT → Absorbs and Resists
Forces of Mastication and Deformation – Grips the
rest. material.
• Grooves, coves, pins etc -completely in Dentin.
75

76. “Vital pulp therapy”
• The reparative Dentin Formation can be stimulated by
cavity lining materials (such as Calcium hydroxide).
• Includes Direct and Indirect pulp capping
• Results in formation of reparative dentin .
• THE DENTINAL BRIDGE repair tissue that forms
across the pulpal wound.
• Sign of successful healing.
76

77. “Bonding to Dentin”
• Adhesion to Dentin… A
CHALLENGE!!
• Due to - ↑organic content, tubular
nature and presence of Fluid.
• Further complicated by “Smear
Layer”- abraded dentin surfaces-denatured
collagen, HA crystals,
debris.(1-4μm thick)
• It decreases dentinal permeability-but
interferes with bonding – should
SMEAR LAYER
be removed. 77

78. • Steps in Bonding:
- Conditioning
- Priming
- Application of Bonding Agent
Hybrid Layer Composed of collagen, Bonding
Agent and Resin
78

79. “Endodontics”
• Secondary & Tertiary Dentin →obliteration of Pulp Chamber
& Root Canals.
• Endodontic treatment → Difficult.
• Periapical surgery- Root Resection- closer to 90o
to minimize no. of exposed tubules.
• Apical Dentin Chip Plug- Dentinal Chips compacted at apex
during Obturation- provides a “biologic seal”
79

80. DEVELOPMENTAL DEFECTS
80

81. Dentinogenesis Imperfecta
Anomaly of Mesodermal Portion of the
Odontogenic Apparatus.
CLASSIFICATION:
(ACC. TO SHIELDS)
TYPE I- Assoc with. O.I.
Type II – Not Assoc with O.I
Type III- Brandy wine Type.
81

82. TYPE I TYPE II TYPE III
CLINICAL
FEATURES
Tulip Shaped teeth, Bluish-grey-
Yellow/Brown
Translucent. Enamel Chips
away→ Exposed dentin,
rapid attrition.
Amber appearance,
Excessive wear,
Multiple pulp
Exposures.
RADIOGRAPHIC
FEATURES
Partial/complete
obliteration of pulp
chamber , root canals
Shell teeth- Normal
Enamel, Thin Dentin,
Huge pulp Chambers,
short roots.

83. TREATMENT
• In patient with DI, one must first ascertain which type
he/she are dealing with.
• Severe cases of DI type 1 associated Osteogenesis
imperfecta can present significant medical
management problems. Careful review of the patient's
medical history will provide clues as to the severity of
bone fragility based on the number of previous
fractures and which bones were involved.

84. • Patients not exhibiting enamel fracturing and
rapid wear crown placement androutine
restorative techniques may be used.
• Bonding of veneers may be used to improve
the esthetics.

85. • In more severe cases, where there is significant
enamel fracturing and rapid dental wear, the treatment
of choice is full coverage crowns.
However in case of D.I III with thin
root are not good cases for full coverage because of
cervical fractures.
• Occlusal wear with loss of vertical dimension –
Metal castings
Newer composites.

86. Dentin Dysplasia (Root less teeth)
 Rare Dental Anomaly.
 Normal Enamel, Atypical
Dentin, Abnormal Pulp
Morphology
 CLASSIFICATION:
(Acc. To WHITKOP)
-TYPE I- RADICULAR
-TYPE II – CORONAL
86

87. TYPE I(RADICULAR) TYPE II (CORONAL)
CLINICAL FEATURES Normal Morphology,
Amber Translucency.
Extreme Mobility and
Premature Exfoliation
Primary- yellow /brown-grey.
Permanent – normal.
RADIOGRAPHIC
FEATURES
Deciduous - pulp
chambers completely
obliterated, short conical
roots.
Permanent – crescent
shaped pulp chambers-
Difficulty in locating
canal orifices.
Deciduous – pulp
chambers obliterated
Permanent -
“thistle tube” appearance
87

88. Regional Odontodysplasia
• Maxillary Anteriors
• CLINICAL
FEATURES: delay or
failure of eruption,
irregular shape.
• RADIOGRAPHIC
FEATURES: “Ghost
Teeth.”
88

89. Treatment:
• No treatment required
• Meticulous oral hygiene
• Extraction / Endodontic treatment
• Prosthetic rehabilitation

90. Dens in Dente
• Dentin & enamel forming
tissue invaginate the whole
length of a tooth.
• Radiographically- “tooth
within a tooth.”
• Food lodges in the cavity to
cause caries which rapidly
penetrates the distorted pulp
chamber
• Endodontic Treatment
Difficult- abnormal Anatomy.
90

91. Tetracycline Pigmentation
• Yellow- Brown/grey
Discoloration.
• Fluoresce Bright
Yellow under U.V
light.
• Deposited along
Incremental lines of
Dentin and to lesser
Extent in Enamel.
91

92. RESPONSE OF DENTIN TO RESTORATIVE
PROCEDURE AND MATERIALS
1) SMEAR LAYER:
The smear layer is an amorphous , relatively smooth layer of
microcrystalline debris with a featureless surface that cannot
be seen with the naked eye [ Pashley DH 1984]
The cutting of dentin during cavity preparation produces
microcrystalline grinding debris that coats the dentin and
clogs the orifices of the dentinal tubules. This layer of debris
is termed as smear layer.

93. • Reduces sensitivity and permeability
• Interferes with the apposition or adhesion of dental
materials to dentin
• Has a potential to provide a media for recurrent caries
and bacterial irritation of the pulp
Methods of removal of smear layer from root canals
before obturation is the alternative use of a chelating
agent(disodium ethylenediamine tetra acetic acid EDTA)
or weak acid i.e. (10 % citric acid) followed by thorough
canal rinsing with 3 to 5 % NaOCl.

94. 2) Restorative procedures can affect the permeability of
remaining dentin
• Minimal effects are transmitted to the pulp if the remaining dentin
thickness is 2mm or more.
• For an amalgam restoration in a deep tooth preparation a total of
1- 2 mm of underlying dentin is preferred.
• For a non metallic restoration which has better insulating
properties than a metallic one, 0.5 – 1mm of dentin or liner / base
is sufficient.

95. • Approximately a 20 fold increase in permeability is seen from
extending a cavity preparation that is 3 mm from the pulp to
0.5 mm
• An acid etchant can increase the permeability by 4- 5 folds as
tubule apertures are enlarged.
• Loss of coronal enamel or cervical cementum exposes dentin
and can produce hyperalgesic response.
• Cementation and impression procedures exert tubular pressure
which results in odontoblastic displacement.

96. 3) THERMAL AGENTS:
• Degree of heat produced depends on instrument
type, speed of rotation , cavity depth, effectiveness
of cooling.
• Metal restorations without insulating base and liner
& heat produced by setting cements irritate pulp by
dehydration of dentinal tubule.

97. 4) CHEMICAL AGENTS:
• Sterilization and disinfecting chemicals applied to the dentin
produce odontoblastic injury
• Alcohol &chloroform produce thermal irritation by evaporation
and dehydrate dentinal tubules
• Hydrogen peroxide may travel through dentinal tubules of deep
cavity preparations and into the pulp producing emboli and
perhaps even arresting circulation.
• Dentin conditioning agents: classic acid etchant used on dentin de
mineralize Peritubular dentin which widens the tubule increasing
permeability.

98. • The acid should be passively applied for short periods 5-15 secs
• This technique leaves behind smear plugs in tubule apertures
• The intact collagen framework interacts with hydrophilic priming
agents which penetrate through the remnant smear layer and into
the Intertubular dentin and fills the spaces left by the dissolved
apatite crystals. This allows acrylic monomers to form an
interpenetrating network around dentin collagen. Once
polymerized , this layer produces what Nakabayashi (1992)
referred to as HYBRID ZONE( Interdiffusion zone or
Interpenetration zone) 0.1 to 5 um deep.

99. • ACID LIQUID COMPONENTS OF CEMENTS: Initial
acidity of zinc phosphate, silicate , zinc polycarboxylate and
glass ionomer cements produce pulpal irritation.
• ACRLIC MONOMER: Produces shrinkage and is unable to
seal effectively produces pulpal irritation
• EUGENOL: Anti inflammatory activity through the inhibition
of prostaglandin synthesis
• Antibacterial
• Anodyne effect through desensitization and blockage of pain
impulse.
• ZOE is found to be the most effective sealing agent

100. 5. RESTORATIVE MATERIALS:
A restoration placed in a cavity preparation can develop
contraction gaps between the restoration and the cavity wall.
This gap then fills with fluid from the outflow of tubules or saliva
from external surface. An environment is created for bacterial
growth and failure of restoration .

101. CONCLUSION…!!!

102. REFERENCES
• Orbans’ Oral Histology and Embryology-G.S Kumar – Twelfth
Edition
• Ten Cate’s Oral Histology- Development, structure and Function-
Antonio Nanci- Sixth Edition.
• Pathways of the pulp- Cohen. Hargreaves- Ninth Edition.
• Shafer’s Textbook of Oral Pathology- Shafer, Hine, Levy-5th
Edition.
• Oral and Maxillofacial Pathology- Neville-3rd Edition.
• The art and science of Operative dentistry- Theodore Sturdevant- 4th
Edition.
• An Atlas and Textbook of Oral Anatomy and Histology- Berkovitz.
• Tooth Wear and sensitivity Clinical Advances in restorative
Dentistry-Martin Addy, Graham Embery, WMichael Edgar
102

103. THANK U
THAN
K
YOU
You can neither win nor lose if you don't run the race
- David Bowie