This document provides information about a seminar on enamel, dentin, and pulp presented by Dr. Ashish Kalhan. It discusses the key structures and properties of enamel, dentin, and pulp. Enamel is the outermost covering of the tooth. It is the hardest tissue in the body and provides protection. It is made up of enamel rods arranged in a prism-like pattern. Dentin lies underneath the enamel and makes up the bulk of the tooth. It contains dentinal tubules that house odontoblast processes. The innermost living tissue is the pulp, which contains blood vessels, nerves, and odontoblasts. The document discusses the physical and chemical properties of enamel

1. SEMINAR ON
ENAMEL ,
DENTIN , PULP
PRESENTED BY :
DR. ASHISH
KALHAN
P.G
( CONSERVATIVE

2. INTRODUCTION
• The tooth is made up of three
structures basically :
# Enamel : outermost covering.
# Dentin : middle layer.
# Pulp : innermost living tissue.

3. ENAMEL
PULP
DENTIN

4. ENAMEL

5. WHAT IS
ENAMEL ???
• IT IS A PROTECTIVE AND
RESISTANT COVERING OF
VARIABLE THICKNESS OVER THE
ENTIRE SURFACE OF THE
CROWN , RENDERING IT
SUITABLE FOR MASTICATION.

6. Physical
characteristics
• hardest calcified tissue in the human
body.
• brittle.
• specific gravity : 2.8
• color : yellowish – white to grayish
white.
• permeability : can act as a semi-
permeable membrane , permitting
complete or partial passage of
certain molecules.

7. • COMPRESSIVE STRENGTH = 384
Mpa
• TENSILE STRENGTH = 10 Mpa
• ELASTIC MODULUS = 84 Gpa
• KNOOP HARDNESS NUMBER (KHN) =
350 – 430
• RADIOPACITY (mm Al) = 2

8. Chemical
characteristics
• Inorganic material : 96 %
- consists of hydroxyapatite crystals
( hexagonal in shape ).
- crystals are arranged to form
enamel rods or enamel prisms.
- core of the crystals richer in mg &
carbonate – reason for their greater
solubility of acids than peripheral
portions.
- pores are present between crystals ,
especially at the boundaries of rods &
thes are filled with water.

9. • Organic material : 4 %
- consists of proteins that are
exclusively found in enamel.
1) amelogenins (90%): low
molecular weight proteins &
hydrophobic.
2 ) nonamelogenins (10%) :
high molecular weight proteins.
- enamel proteins do not
contribute to structuring of
enamel.

10. structure
• It is composed
of enamel rods ,
rod sheaths & in
some regions a
cementing
interprismatic
substance.
A. ROD CORE
B. ROD SHEATH
C. ROD TAIL
D. ROD HEAD

11. Enamel rods
• Enamel rods have a somewhat wavy course
outward toward the surface.
• Rods located at the cusps are longer
than those at the cervical areas of teeth.
• Diameter of rods increase from
Dentinoenamel junction toward the
surface at ratio of 1:2.
• Common pattern : key-hole shaped.
• Rods measure 5 µ in breadth & 9 µ in
length.

12. Enamel rods
In cross section the key – hole shaped
pattern of enamel can be seen. Also the
wavy course of rods can be seen.

13. Direction of rods :
• Right angle to the
dentin surface.
• Vertical in the
cuspal region , more
oblique as they go
cervically.
• In deciduous teeth,
it is horizontal
cervically.
• In permanent teeth,
it is directed more
gingivally.

14. Each rod built up of segments separated by dark
lines – striated appearance. It is more pronounced
in enamel that is insufficiently calcified. The
striations are approximately 5 µ apart. This distance
represents one day of enamel deposition.
Reason : segmented because enamel matrix formed
in a rhythmic manner.

15. Gnarled enamel
• Enamel rods are not
always straight. In
region of cusps and
incisal edges, bundles
of rods interwine more
irregularly.
• This optical appearance
of enamel is gnarled
enamel.
A. GNARLED ENAMEL
B. ENAMEL SPINDLE

16. Hunter-Schreger bands
• ALTERNATE LIGHT AND DARK BANDS OF
VARYING WIDTHS.
• ORIGINATE AT DENTINOENAMEL BORDER &
PASS OUTWARD, ENDING AT SOME DISTANCE
FROM ENAMEL SURFACE.
• CAN BE BEST SEEN IN LONGITUDINAL GROUND
SECTION UNDER OBLIQUE REFLECTED LIGHT.
• PRISMS THAT ARE CUT LONGITUDINALLY –
PRODUCE DARK BANDS - CALLED PARAZONES.
• THOSE THAT ARE CUT TRANSVERSELY –
PRODUCE LIGHT BANDS - CALLED DIAZONES.

17. •ANGLE BETWEEN
PARAZONES AND
DIAZONES : 40˚
•REASON FOR
OCCURRENCE :
CHANGE IN DIRECTION
OF RODS REGARDED AS
A FUNCTIONAL
ADAPTATION MINIMIZING
RISK OF CLEAVAGE IN
AXIAL DIRECTION.

18. Incremental lines of retzius
• APPEAR AS BROWNISH BANDS IN GROUND
SECTION.
• THEY ILLUSTRATE SUCCESSIVE APPOSITION OF
LAYERS OF ENAMEL DURING CROWN
FORMATION.
• IN TRANSVERSE SECTION - CONCENTRIC
CIRCLES.
• IF PRESENT IN MODERATE INTENSITY – NORMAL.
• BUT DUE TO METABOLIC DISTURBANCES , REST
PERIODS BECOME UNDULY PROLONGED – LINES
BECOME MORE PROMINENT.

19. INCREMENTAL LINES OF
RETZIUS

20. Neonatal line
• The enamel of deciduous
teeth develops partly
before and partly after
birth.
• Boundary between 2
portions of enamel
marked by an accentuated
incremental line –
neonatal line / ring.
• It is as a result of abrupt
change in the
environment & nutrition
of newborn infant.

21. Enamel lamellae
• THIN LEAF – LIKE STRUCTURES THAT EXTEND IN
LONGITUDINAL & RADIAL DIRECTION OF TOOTH,
FROM TIP OF CROWN TOWARD CERVICAL REGION.
• MAY DEVELOP IN PLANES OF TENSION.
• TYPE A : COMPOSED OF POORLY CALCIFIED ROD
SEGMENTS.
• TYPE B : CONSISTING OF DEGENERATED CELLS.
• TYPE C : ARISING IN ERUPTED TEETH WHERE
CRACKS ARE FILLED WITH ORGANIC MATTER.

22. • LAMELLAE MAY BE
A SITE OF
WEAKNESS IN A
TOOTH & MAY
FORM A ROAD OF
ENTRY FOR
BACTERIA THAT
INITIATE CARIES.
A. ENAMEL TUFTS
B. ENAMEL LAMALLAE

23. Enamel Tufts
• NARROW RIBBON – LIKE STRUCTURES THAT
ARISE IN THE DENTINOENAMEL JUNCTION &
REACH INTO ENAMEL .
• CONSISTS OF HYPOCALCIFIED RODS &
INTERPRISMATIC SUBSTANCE.
• THEIR PRESENCE AS A RESULT OF
ADAPTATION TO THE SPATIAL CONDITIONS IN
ENAMEL.
• THEY ALSO EXTEND IN THE DIRECTION OF
LONG AXIS OF CROWN.

24. A. ENAMEL SPINDLE
B. ENAMEL TUFT

25. Enamel spindle & odontoblast
process • WHEN
ODONTOBLAST
PROCESS PASS
ACROSS
DENTINOENAMEL
JUNCTION,
THICKENED
PROCESSES AT THE
END IN THE ENAMEL
ARE – SPINDLES.
A. ENAMEL SPINDLE • RIGHT ANGLED TO
THE DENTIN
B. ODONTOBLAST SURFACE.
PROCESS

26. A. BRANCHING OF ODONTOBLAST PROCESS
B.DENTINOENAMEL JUNCTION
C. DENTIN
D. ODONTOBLAST PROCESS

27. Dentinoenamel junction (DEJ)
• IT IS SCALLOPED TYPICALLY WITH THE
CONVEXITIES OF THE SCALLOPS DIRECTED
TOWARDS THE DENTIN.
• ASSURES FIRM HOLD OF ENAMEL CAP ON
DENTIN.
• THE DEJ IS A SERIES OF RIDGES & IS
MORE PRONOUNCED IN OCCLUSAL AREA ,
WHERE MASTICATORY STRESSES ARE
GREATER.

28. AGE CHANGES IN
ENAMEL
• Most apparent – attrition
• Clinical significance – loss of vertical
dimension of crown & flattening of
proximal contour.
• Facial & lingual surfaces lose their
structure much more rapidly than
proximal & anteriors more rapidly
than posteriors.

29. • AS A RESULT OF CHANGES IN ORGANIC
PORTION OF ENAMEL ,TEETH BECOME DARKER ,
& RESISTANCE TO DECAY IS INCREASED.
• ALSO , DECREASED PERMEABILITY OF OLDER
TEETH TO FLUIDS.
REASON : IONS ACQUIRED FROM ORAL FLUIDS
INCREASE IN SIZE OF CRYSTAL
DECREASES THE PORES BETWEEN THEM
REDUCED PERMEABILITY !!!

30. CLINICAL
CONSIDERATIONS
• IN PREPARING CAVITIES , ITS IMPORTANT
THAT UNSUPPORTED ENAMEL RODS NOT
LEFT AT THE MARGINS.
WOULD BREAK & PRODUCE LEAKAGE.
SECONDARY DENTAL CARIES.

31. INCORREC
T
CORRECT
NO
UNSUPPORTED
ENAMEL RODS
SHOULD BE
LEFT WHEN
PREPARING THE
WALLS OF THE
CAVITY

32. • DEEP ENAMEL FISSURES PREDISPOSE TO
CARIES.
• CARIES PENETRATE THE FLOOR OF FISSURES
RAPIDLY BECAUSE ENAMEL HERE IS VERY THIN.
• SURFACE OF ENAMEL IN CERVICAL REGION
SHOULD BE KEPT WELL POLISHED.
IF DECALCIFIED OR ROUGHENED
FOOD DEBRIS ACCUMULATE & GINGIVA IN
CONTACT WITH THIS REGION UNDERGO
INFLAMMATORY CHANGES.

33. DENTIN

34. PHYSICAL PROPERTIES
• IN YOUNG , DENTIN IS USUALLY LIGHT
YELLOWISH IN COLOUR , BECOMING DARKER
WITH AGE.
• VISCOELASTIC – SUBJECT TO SLIGHT
DEFORMATION.
• HARDER THAN BONE !! SOFTER THAN ENAMEL !!
• HARDER IN CENTRAL PART THAN NEAR PULP !
• DUE TO LOWER CONTENT OF MINERAL SALTS -
MORE RADIOLUCENT THAN ENAMEL.

35. • COMPRESSIVE STRENGTH = 297 Mpa
• TENSILE STRENGTH = 52 Mpa
• ELASTIC MODULUS = 18 Gpa
• KNOOP HARDNESS NUMBER (KHN) = 68
• RADIOPACITY (mm Al) = 1

36. CHEMICAL PROPERTIES
Inorganic material (65 %):
• Consists of hydroxyapatite crystals.
• Each crystal composed of several
thousand unit cells of 3Ca (PO4)2 . Ca
(OH)2.
• Crystals are plate – shaped & much
smaller than that of enamel.
• Crystals poor in calcium but rich in
carbon when compared to enamel.

37. • Organic material (35 %):
• Consists of collagenous fibrils embedded in
ground substance of mucopolysaccharides.
• Type 1 collagen - principal type.
• Important constituents of ground substance :
Proteoglycan dentin sialoprotein
dentin phosphoproteins phospholipid
These matrix components have an important
role to play in mineralisation of dentin.

38. Structure
• TUBULES ARE FOUND
THROUGHOUT NORMAL
DENTIN & HENCE
CHARACTERISTIC OF IT.
• BODIES OF
ODONTOBLASTS ARE
ARRANGED IN A LAYER
ON PULPAL SURFACE
OF DENTIN.
A. ODONTOBLAST PROCESS • THEIR CYTOPLASMIC
PROCESSES ARE
B. PERITUBULAR DENTIN INCLUDED IN THE
TUBULES IN THE MATRIX.
C. INTERTUBULAR DENTIN

39. Dentinal tubules
• TUBULES FOLLOW A GENTLE ‘S’ ( SIGMOID
SHAPE ) IN THE DENTIN, MORE SO IN ROOT –
PRIMARY CURVATURES.
• START AT RIGHT ANGLES FROM PULPAL
SURFACE & END PERPENDICULAR TO DEJ.
• TERMINAL BRANCHING MORE PROFUSE IN
ROOT DENTIN.
• OVER THEIR ENTIRE LENGTHS , TUBULES
EXHIBIT MINUTE RELATIVELY REGULAR
SECONDARY CURVATURES THAT ARE
SINUSOIDAL IN SHAPE.

40. A. PRIMARY CURVATURE OF A. PERITUBULAR DENTIN
DENTINAL TUBULES
B. INTERTUBULAR DENTIN
B. DENTINOENAMEL
JUNCTION C. DENTINAL TUBULE

41. SECONDARY CURVES
DURING DEVELOPMENT OF DENTIN , THE ODONTOBLAST
MAKES SLIGHT UNDULATIONS THAT CREATES WAVY
DENTINAL TUBULES. THIS WAVINESS ARE CALLED
SECONDARY CURVATURES.

42. • THICKNESS OF DENTIN = 3 -10 mm.
• RATIO BETWEEN OUTER & INNER SURFACES
OF DENTIN = 5 : 1
• BOYS – THICKER ; BUCCAL SURFACES –
THICKEST.
• RATIO BETWEEN NUMBER OF DENTINAL
TUBULES / UNIT AREA ON PULPAL & OUTER
SURFACES OF DENTIN = 4 : 1
• DENTINAL TUBULES HAVE LATERAL
BRANCHES THROUGHOUT DENTIN -
CANALICULI / MICROTUBULES.

43. A. ODONTOBLAST PROCESS
B. CANALICULI / LATERAL
BRANCH
• DENTINAL TUBULES HAVE LATERAL BRANCHES WHERE
ODONTOBLASTIC PROCESSES CAN COMMUNICATE WITH EACH OTHER.
• MOST NUMEROUS IN THE ROOT REGION.

44. Peritubular Dentin
• THE DENTIN THAT
SURROUNDS THE
DENTINAL TUBULES.
• FORMS THE WALL OF
THE TUBULES IN ALL
BUT THE DENTIN
NEAR THE PULP.
• MORE HIGHLY
MINERALISED THAN A. INTERTUBULAR DENTIN
DENTIN PRESENT IN
BETWEEN TUBULES. B. PERITUBULAR DENTIN
C. DENTINAL TUBULE

45. Dentinal fluid
• BETWEEN ODONTOBLASTIC PROCESS &
PERITUBULAR DENTIN , A SPACE KNOWN AS
PERIODONTOBLASTIC SPACE IS PRESENT.
• THIS SPACE CONTAINS THE DENTINAL FLUID.
• NORMAL FLOW OF FLUID IS OUTWARDS FROM
THE PULP.
• CONTAINS HIGHER K⁺ & LOWER Na⁺.
• DENTIN SENSITIVITY IS EXPLAINED ON THE BASIS
OF THIS FLUID MOVEMENT.

46. Intertubular Dentin
• COMPRISES THE MAIN BODY OF DENTIN.
• LOCATED BETWEEN THE TUBULES OR MORE
SPECIFICALLY BETWEEN ZONES OF PERITUBULAR
DENTIN.
• RETAINED AFTER DECALCIFICATION , WHEREAS
PERITUBULAR DENTIN IS NOT.
• ABOUT ONE – HALF OF ITS VOLUME IS ORGANIC
MATRIX , SPP. COLLAGEN FIBERS.
• HYDROXYAPATITE CRYSTALS FORMED ALONG
FIBERS WITH LONG AXIS ORIENTED PARALLEL TO
FIBERS.

47. Predentin • LOCATED ALWAYS
ADJACENT TO THE
PULP.
• 2 – 6 µm WIDE ,
DEPENDING ON
THE ACTIVITY OF
ODONTOBLAST.
• NOT MINERALISED.
A. DENTIN MINERALISATION FRONT
B. DENTIN C. PREDENTIN
D. ODONTOBLASTS E. PULP

48. DIFFERENT TYPES OF
DENTIN
1 ) PRIMARY DENTIN
MANTLE DENTIN
CIRCUMPULPAL DENTIN
2 ) SECONDARY DENTIN
3 ) TERTIARY / REPAIRATIVE
DENTIN

49. A.PRIMARY DENTIN
B. SECONDARY DENTIN

50. Mantle Dentin
• FIRST FORMED
DENTIN IN THE
CROWN UNDERLYING
THE DEJ.
• 20 µm THICK.
• LESS MINERALISED
THAN CIRCUMPULPAL
DENTIN.
A. ENAMEL
• MATRIX COMPOSED
B. CIRCUMPULPAL DENTIN
OF VON KORFF ‘S
FIBERS.
C. MANTLE DENTIN

51. VON KORFF‘S FIBERS
• LARGER DIAMETER COLLAGEN FIBERS.
• ARGYROPHILLIC ( SILVER STAINING ) .
• MAINLY TYPE 3 COLLAGEN.
• FOUND IN MANTLE DENTIN.

52. Circumpulpal dentin
• FORMS THE REMAINING DENTIN OR
BULK OF THE TOOTH.
• REPRESENTS ALL THE DENTIN
FORMED BEFORE ROOT
COMPLETION.
• COLLAGEN FIBRILS MUCH SMALLER
IN DIAMETER AND CLOSELY PACKED
TOGETHER THAN MANTLE DENTIN.

53. Secondary Dentin
• REPRESENTS THE DENTIN FORMED AFTER
ROOT COMPLETION.
• FEWER TUBULES THAN PRIMARY DENTIN.
• APPEARS IN GREATER AMOUNT ON ROOF &
FLOOR OF CORONAL PULP CHAMBER –
PROTECTS PULP FROM EXPOSURE IN
OLDER TEETH.
• FORMED NOT IN RESPONSE TO ANY
EXTERNAL STIMULI.

54. A. PULP
B. PRIMARY DENTIN
C. SECONDARY DENTIN

55. Incremental lines of von Ebner
• REFLECTS THE DAILY RHYTHMIC ,
RECURRENT DEPOSITION OF DENTIN
MATRIX.
• DISTANCE BETWEEN LINE VARIES FROM 4 –
8 µm IN CROWN TO MUCH LESS IN THE
ROOT.
• SOMETIMES ACCENTUATED – DUE TO
DISTURBANCES IN MATRIX &
MINERALISATION PROCESS - CONTOUR
LINES OF OWEN.

56. INCREMENTAL LINES CONTOUR LINES OF
OF VON EBNER OWEN

57. A.CONTOUR
LINES
OF
OWEN.
B.STRIAE
OF
RETZIUS
THE CONTOUR LINES OF OWEN INTERCEPT THE
DENTINOENAMEL JUNCTION & INTERCEPT THE
ACCOMPANYING STRIAE OF RETZIUS THAT WAS
FORMED AT THE SAME TIME.

58. Interglobular dentin
• ZONES OF
HYPOMINERALISA
TION BETWEEN
GLOBULAR AREAS
THAT FAIL TO
COALESCE INTO A
HOMOGENOUS
MASS.
• FORMS IN CROWN
OF TEETH IN A. INTERGL
CIRCUMPULPAL OBULAR
DENTIN – FOLLOWS DENTIN
INCREMENTAL
PATTERN. B. GLOBULA

59. INTERGLOBULAR
DENTIN

60. Tomes granular layer
• GRANULAR ZONE
ADJACENT TO
CEMENTUM WHEN
GROUND SECTIONS OF
ROOT DENTIN SEEN IN
TRANSMITTED LIGHT.
• CAUSE : COALESCING &
LOOPING OF THE
TERMINAL PORTIONS OF
THE DENTINAL
TUBULES.
• AMONG
A. TOMES GRANULAR LAYER
HYPOMINERALISED
AREAS – HIGHEST
B. CEMENTUM CONCENTRATION OF
CALCIUM &
C. CONTOUR LINES OF OWEN PHOSPHORUS.

61. Dentin permeability
• DEPENDS UPON PATENCY OF DENTINAL
TUBULES.
SMEAR
TUBULAR
LAYER
OCCLUSION
FORMATION
REDUCED PERMEABILITY
DECREASED SENSITIVITY

62. AGE & FUNCTIONAL
CHANGES
• PATHOLOGIC EFFECTS OF CARIES,
ATTRITION, ABRASION OR CUTTING OF
DENTIN BY OPERATIVE PROCEDURES
CAUSE CHANGES IN DENTIN :

63. Repairative dentin
INTENSITY OF INJURY
• ODONTOBLASTS DIE SURVIVE
• REPLACED BY DENTIN THAT IS
MIGRATION OF PRODUCED
UNDIFFERENTIATED HENCEFORTH IS
CELLS FROM DEEPER
REGIONS OF PULP.
REPAIRATIVE
DENTIN

64. Repairative dentin (Contd…)
• OCCURS AS A HEALING PROCESS TO SEAL
OFF THE ZONE OF INJURY.
• FEWER & MORE TWISTED TUBULES.
• DUE TO THIS IRREGULAR NATURE OF TUBULES
ITS CALLED IRREGULAR SECONDARY
DENTIN.
• DIFFERS FROM OTHER FORMS OF DENTIN IN
THAT DENTIN PHOSPHOPHORYN IS NOT
PRESENT.

65. Dead tracts
• DENTIN AREAS CHARACTERIZED BY
DEGENERATED ODONTOBLAST PROCESSES
GIVE RISE TO DEAD TRACTS.
• THESE AREAS DEMONSTRATE DECREASED
SENSITIVITY & APPEAR MOSTLY IN OLDER
TEETH.
• APPEAR BLACK IN TRANSMITTED LIGHT &
WHITE IN REFLECTED LIGHT.
• ARE PROBABLY THE INITIAL STEP IN
FORMATION OF SCLEROTIC DENTIN.

66. DEAD TRACTS

67. Sclerotic dentin
• ALSO IN CARIES, ATTRITION, ABRASION
• SUFFICIENT STIMULI GENERATED TO CAUSE
COLLAGEN FIBERS & APATITE CRYSTALS
TO BEGIN APPEARING IN DENTINAL
TUBULES.
DEFENSIVE ACTION OF TUBULES / DENTIN.
SCLEROTIC DENTIN.

68. Sclerotic dentin (Contd…)
• BY BLOCKING THE TUBULES , IT REDUCES
DENTIN PERMEABILITY – PROLONGS THE
PULP VITALITY.
• ALSO CALLED TRANSPARENT DENTIN.
• OBSERVED IN OLDER PEOPLE , ESPECIALLY
IN ROOTS.
• MINERAL DENSITY GREATER HERE.
• APPEARS LIGHT IN TRANSMITTED LIGHT &
DARK IN REFLECTED LIGHT.

69. SCLEROTIC
DENTIN

70. CLINICAL
CONSIDERATIONS
RAPID PENETRATION & SPREAD OF CARIES IN
DENTIN IS DUE TO THE TUBULE SYSTEM.
PROVIDE A PASSAGE FOR INVADING BACTERIA & THEIR
PRODUCTS.
( TUBULES ARE ENLARGED BY DESTRUCTIVE
ACTION OF MICROORGANISMS. )
MOST ACCEPTED THEORY FOR SENSITIVITY OF DENTIN
IS - HYDRODYNAMIC THEORY.
ALTERATION OF FLUID & CELLULAR CONTENTS OF
TUBULES CAUSE STIMULATION OF NERVE ENDINGS
IN CONTACT WITH THESE CELLS.

71. Dentin resorption
A.DENTINOCLASTS
B. DENTIN C. PULP

72. PULP

73. GENERAL FEATURES
• PULP OCCUPIES THE CENTER OF EACH TOOTH &
CONSISTS OF SOFT CONNECTIVE TISSUE.
IN CROWN - CORONAL PULP
IN ROOT - RADICULAR PULP
• TOTAL VOLUMES OF ALL PERMANENT TEETH = 0.38
CC
MEAN VOLUME OF SINGLE ADULT PULP = 0.02 CC
• AVERAGE SIZE OF APICAL FORAMEN :
MAXILLARY = 0.4 MM
MANDIBULAR = 0.3 MM

74. STRUCTURAL FEATURES
• CENTRAL REGION – LARGE NERVE TRUNKS
& BLOOD VESSELS.
• PERIPHERALLY – SPECIALISED ODONTOGENIC
REGION COMPOSED OF :
1) ODONTOBLASTS
2) WEIL ‘S ZONE ( CELL – FREE ZONE ) :
SPACE IN WHICH ODONTOBLAST MAY
MOVE PULPWARD DURING TOOTH
DEVELOPMENT & SOMETIMES LATER.
3) CELL – RICH ZONE : COMPOSED OF
FIBROBLASTS & UNDIFFERENTIATED
MESENCHYMAL CELLS.

76. ARTERIOLE
FIBROBLASTS
NERVE
BUNDLE

77. Nerve plexus of Raschkow
• SENSORY NERVE FIBERS
THAT ORIGINATE FROM
SUPERIOR & INFERIOR
ALVEOLAR NERVES
INNERVATE THE
ODONTOBLASTIC LAYER
OF THE PULP CAVITY.
• THESE NERVES ENTER
THE TOOTH THROUGH
THE APICAL FORAMEN AS
MYELINATED NERVE
BUNDLES.
A. ODONTOBLASTS
• THEY BRANCH TO FORM
SUBODONTOBLASTIC B. CELL – FREE WEIL ‘ S ZONE
NERVE PLEXUS OF
RASCHKOW. C. NERVE PLEXUS OF
RASCHKOW

78. Fibroblasts
• PRINCIPLE CELL TYPE IN PULP.
• FUNCTION IN COLLAGEN FIBER
FORMATION DURING LIFE OF THE TOOTH.
• HAVE TYPICAL STELLATE SHAPE &
EXTENSIVE PROCESSES THAT CONTACT VIA
INTERCELLULAR JUNCTIONS TO OTHER
FIBROBLASTS.
• MAIN TYPE OF COLLAGEN – TYPE 1.

79. Odontoblasts
• RESIDE ADJACENT TO PREDENTIN WITH CELL BODIES
IN PULP & CELL PROCESSES IN DENTINAL TUBULES.
• 5 – 7 µm DIAMETER ; 25 – 40 µm IN LENGTH.
• CELL BODIES ARE COLUMNAR IN APPEARANCE WITH
LARGE OVAL NUCLEI , WHICH FILL THE BASAL PART OF
CELL.
• IN CROWN - MORE CYLINDRICAL & LONGER.
• IN ROOT – OVOID & SPINDLE SHAPED.
• ARE END – CELLS : LOST THE ABILITY TO DIVIDE – SO
HAVE TO BE REPLACED.

80. FUNCTIONS
• INDUCTIVE : INTERACT WITH ORAL
EPITHELIAL CELLS
DIFFERENTIATION OF DENTAL LAMINA &
ENAMEL ORGAN FORMATION.
• FORMATIVE : CELLS IN PULP PRODUCE
DENTIN THAT SURROUND THE PULP.
• NUTRITIVE : NOURISHES DENTIN BY
MEANS OF ITS VASCULAR SYSTEM
THROUGH ODONTOBLASTS & ITS
PROCESSES.

81. • PROTECTIVE : NERVES RESPOND WITH
PAIN TO ALL STIMULI SUCH AS HEAT ,
COLD , PRESSURE , ETC.
- ALSO INITIATE REFLEXES THAT CONTROL
CIRCULATION IN PULP.
• REPAIRATIVE : PULP RESPONDS TO
IRRITATION BY PRODUCING REPAIRATIVE
DENTIN & MINERALISING ANY AFFECTED
DENTINAL TUBULES.

82. REGRESSIVE CHANGES
(AGING )
• CELLS : FEWER CELLS IN OLDER PULP.
- DECREASE IN SIZE & NUMBER OF
CYTOPLASMIC ORGANELLES.
- FIBROBLASTS BECOME SPINDLE SHAPED WITH
SHORT PROCESSES - FIBROCYTES.
• FIBROSIS : ACCUMULATION OF BOTH
DIFFUSE FIBRILLAR COMPONENTS & BUNDLES
OF COLLAGEN FIBERS APPEAR.

83. Pulp stones ( Denticles )
• NODULAR CALCIFIED MASSES APPEARING
IN EITHER OR BOTH CORONAL & ROOT
PORTIONS.
• USUALLY ASYMPTOMATIC UNLESS THEY
IMPINGE ON NERVES OR BLOOD VESSELS.
• CLASSIFIED : 1) TRUE DENTICLES
2) FALSE DENTICLES.
• ALSO CLASSIFIED AS FREE , ATTACHED
OR EMBEDDED , DEPENDING ON
RELATION TO DENTIN.

84. TRUE
A.
PULP
STONE
B. PULP
CAVITY
C. DENTIN

85. FALSE
DENTICLE

86. Diffuse calcifications
• APPEAR AS
IRREGULAR
CALCIFIC DEPOSITS
IN PULP TISSUE ,
FOLLOWING FIBER
BUNDLES OR
BLOOD VESSELS.
• USUALLY FOUND IN
ROOT CANAL &
LESS IN CORONAL
PORTION WHILE
DENTICLES MORE
IN CORONAL PULP.

87. Clinical considerations
• WIDE PULP CHAMBER & HIGH PULP HORNS IN
TEETH IN YOUNG PERSONS WILL MAKE A DEEP
CAVITY HAZARDOUS.
• WITH ADVANCING AGE : PULP CHAMBER BECOMES
SMALLER + EXCESSIVE DENTIN DEPOSITED
DIFFICULT TO LOCATE ROOT CANALS.
• ALL OPERATIVE PROCEDURES CAUSE RESPONSE IN
PULP – • INFLAMMATORY CELL INFILTRATION ,
• HYPEREMIA
• EVEN HAEMORRHAGE & ABSCESSES.
DEPENDING UPON THE SEVERITY OF STIMULUS.

88. DEVELOPMENT
DENTAL
LAMINA
ECTOMESENCHYME

89. A. INNER ENAMEL EPITHELIUM C. STELLATE RETICULUM
B. OUTER ENAMEL EPITHELIUM D. SUCCESSIONAL LAMINA
E. DENTAL LAMINA F. DENTAL PAPILLA
G. DENTAL SAC

90. A. PREAMELOBLASTS C. STELLATE RETICULUM
B. PREODONTOBLASTS D. DENTAL PAPILLA

91. PREODONTOBLASTS
BASEMENT
MEMBRANE
PREAMELOBLASTS

92. ODONTOBLAST
NUCLEUS
SECRETORY END
OF
ODONTOBLAST
PREDENTIN

93. DENSE
GRANULES
STRIATED
BORDER
RESPONSIBLE
FOR
RESORPTION
OF MATRIX
COMPONENTS
DURING
MATURATION
OF
AMELOBLASTS
IMMATURE
ENAMEL
MATURE
ENAMEL

94. A. ODONTOBLASTS B. PREDENTIN
C. AMELOBLASTS D. ENAMEL
E. DENTIN

95. A. REDUCED ENAMEL EPITHELIUM
B. MATURATIVE / PROTECTIVE AMELOBLASTS
C. CAPILLARIES

96. REFERENCES
• ORBAN ‘ S ORAL HISTOLOGY &
EMBRYOLOGY ( 12TH EDITION )
• ORBAN ‘ S ORAL HISTOLOGY (10TH EDITION)
• PHILLIPS ‘ SCIENCE OF DENTAL MATERIALS
( 11TH EDITION )
• MARZOUK ‘ S OPERATIVE DENTISTRY
• INTERNET