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1 enamel dentin pulp
 

1 enamel dentin pulp

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    1 enamel dentin pulp 1 enamel dentin pulp Presentation Transcript

    • SEMINAR ON ENAMEL ,DENTIN , PULP PRESENTED BY : DR. ASHISH KALHAN P.G ( CONSERVATIVE
    • INTRODUCTION• The tooth is made up of three structures basically :# Enamel : outermost covering.# Dentin : middle layer.# Pulp : innermost living tissue.
    • ENAMEL PULP DENTIN
    • ENAMEL
    • 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.
    • 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.
    • • COMPRESSIVE STRENGTH = 384 Mpa• TENSILE STRENGTH = 10 Mpa• ELASTIC MODULUS = 84 Gpa• KNOOP HARDNESS NUMBER (KHN) = 350 – 430• RADIOPACITY (mm Al) = 2
    • 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.
    • • Organic material : 4 %- consists of proteins that areexclusively found in enamel.1) amelogenins (90%): lowmolecular weight proteins &hydrophobic.2 ) nonamelogenins (10%) :high molecular weight proteins.- enamel proteins do notcontribute to structuring ofenamel.
    • 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
    • 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.
    • Enamel rodsIn cross section the key – hole shapedpattern of enamel can be seen. Also thewavy course of rods can be seen.
    • 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.
    • Each rod built up of segments separated by darklines – striated appearance. It is more pronouncedin enamel that is insufficiently calcified. Thestriations are approximately 5 µ apart. This distancerepresents one day of enamel deposition.Reason : segmented because enamel matrix formedin a rhythmic manner.
    • 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
    • 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.
    • •ANGLE BETWEENPARAZONES ANDDIAZONES : 40˚•REASON FOROCCURRENCE :CHANGE IN DIRECTIONOF RODS REGARDED ASA FUNCTIONALADAPTATION MINIMIZINGRISK OF CLEAVAGE INAXIAL DIRECTION.
    • 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.
    • INCREMENTAL LINES OF RETZIUS
    • 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.
    • 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.
    • • 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
    • 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.
    • A. ENAMEL SPINDLEB. ENAMEL TUFT
    • Enamel spindle & odontoblastprocess • 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
    • A. BRANCHING OF ODONTOBLAST PROCESSB.DENTINOENAMEL JUNCTIONC. DENTIND. ODONTOBLAST PROCESS
    • 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.
    • 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.
    • • 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 !!!
    • CLINICAL CONSIDERATIONS• IN PREPARING CAVITIES , ITS IMPORTANT THAT UNSUPPORTED ENAMEL RODS NOT LEFT AT THE MARGINS. WOULD BREAK & PRODUCE LEAKAGE. SECONDARY DENTAL CARIES.
    • INCORREC T CORRECT NO UNSUPPORTED ENAMEL RODS SHOULD BE LEFT WHENPREPARING THEWALLS OF THE CAVITY
    • • 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.
    • DENTIN
    • 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.
    • • COMPRESSIVE STRENGTH = 297 Mpa• TENSILE STRENGTH = 52 Mpa• ELASTIC MODULUS = 18 Gpa• KNOOP HARDNESS NUMBER (KHN) = 68• RADIOPACITY (mm Al) = 1
    • CHEMICAL PROPERTIESInorganic 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.
    • • 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 phospholipidThese matrix components have an important role to play in mineralisation of dentin.
    • 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 AREB. PERITUBULAR DENTIN INCLUDED IN THE TUBULES IN THE MATRIX.C. INTERTUBULAR DENTIN
    • 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.
    • A. PRIMARY CURVATURE OF A. PERITUBULAR DENTIN DENTINAL TUBULES B. INTERTUBULAR DENTINB. DENTINOENAMEL JUNCTION C. DENTINAL TUBULE
    • SECONDARY CURVESDURING DEVELOPMENT OF DENTIN , THE ODONTOBLASTMAKES SLIGHT UNDULATIONS THAT CREATES WAVYDENTINAL TUBULES. THIS WAVINESS ARE CALLEDSECONDARY CURVATURES.
    • • 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.
    • A. ODONTOBLAST PROCESS B. CANALICULI / LATERAL BRANCH• DENTINAL TUBULES HAVE LATERAL BRANCHES WHEREODONTOBLASTIC PROCESSES CAN COMMUNICATE WITH EACH OTHER.• MOST NUMEROUS IN THE ROOT REGION.
    • 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
    • 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.
    • 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.
    • Predentin • LOCATED ALWAYS ADJACENT TO THE PULP. • 2 – 6 µm WIDE , DEPENDING ON THE ACTIVITY OF ODONTOBLAST. • NOT MINERALISED.A. DENTIN MINERALISATION FRONTB. DENTIN C. PREDENTIND. ODONTOBLASTS E. PULP
    • DIFFERENT TYPES OF DENTIN1 ) PRIMARY DENTIN MANTLE DENTIN CIRCUMPULPAL DENTIN2 ) SECONDARY DENTIN3 ) TERTIARY / REPAIRATIVE DENTIN
    • A.PRIMARY DENTIN B. SECONDARY DENTIN
    • 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
    • VON KORFF‘S FIBERS• LARGER DIAMETER COLLAGEN FIBERS.• ARGYROPHILLIC ( SILVER STAINING ) .• MAINLY TYPE 3 COLLAGEN.• FOUND IN MANTLE DENTIN.
    • 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.
    • 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.
    • A. PULP B. PRIMARY DENTINC. SECONDARY DENTIN
    • 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.
    • INCREMENTAL LINES CONTOUR LINES OF OF VON EBNER OWEN
    • A.CONTOUR LINES OF OWEN. B.STRIAE OF RETZIUSTHE CONTOUR LINES OF OWEN INTERCEPT THEDENTINOENAMEL JUNCTION & INTERCEPT THEACCOMPANYING STRIAE OF RETZIUS THAT WASFORMED AT THE SAME TIME.
    • 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
    • INTERGLOBULAR DENTIN
    • 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. • AMONGA. TOMES GRANULAR LAYER HYPOMINERALISED AREAS – HIGHESTB. CEMENTUM CONCENTRATION OF CALCIUM &C. CONTOUR LINES OF OWEN PHOSPHORUS.
    • Dentin permeability• DEPENDS UPON PATENCY OF DENTINAL TUBULES. SMEAR TUBULAR LAYER OCCLUSION FORMATION REDUCED PERMEABILITY DECREASED SENSITIVITY
    • AGE & FUNCTIONAL CHANGES• PATHOLOGIC EFFECTS OF CARIES, ATTRITION, ABRASION OR CUTTING OF DENTIN BY OPERATIVE PROCEDURES CAUSE CHANGES IN DENTIN :
    • 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
    • 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.
    • 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.
    • DEAD TRACTS
    • 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.
    • 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.
    • SCLEROTIC DENTIN
    • 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.
    • Dentin resorption A.DENTINOCLASTS B. DENTIN C. PULP
    • PULP
    • 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
    • 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.
    • ARTERIOLE FIBROBLASTS NERVEBUNDLE
    • 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
    • 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.
    • 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.
    • 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.
    • • 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.
    • 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.
    • 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.
    • TRUEA. PULP STONEB. PULP CAVITYC. DENTIN
    • FALSEDENTICLE
    • 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.
    • 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.
    • DEVELOPMENT DENTAL LAMINA ECTOMESENCHYME
    • A. INNER ENAMEL EPITHELIUM C. STELLATE RETICULUMB. OUTER ENAMEL EPITHELIUM D. SUCCESSIONAL LAMINAE. DENTAL LAMINA F. DENTAL PAPILLA G. DENTAL SAC
    • A. PREAMELOBLASTS C. STELLATE RETICULUMB. PREODONTOBLASTS D. DENTAL PAPILLA
    • PREODONTOBLASTS BASEMENT MEMBRANEPREAMELOBLASTS
    • ODONTOBLAST NUCLEUSSECRETORY END OF ODONTOBLASTPREDENTIN
    • DENSE GRANULES STRIATED BORDER RESPONSIBLE FOR RESORPTION OF MATRIX COMPONENTS DURING MATURATION OF AMELOBLASTSIMMATURE ENAMELMATUREENAMEL
    • A. ODONTOBLASTS B. PREDENTIN C. AMELOBLASTS D. ENAMEL E. DENTIN
    • A. REDUCED ENAMEL EPITHELIUMB. MATURATIVE / PROTECTIVE AMELOBLASTSC. CAPILLARIES
    • 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