Pulp dentin complex

pulp dentin

1. PULPODENTINAL COMPLEX PRESENTED BY UPAMA SISHAN

2. CONTENTS DENTIN INTRODUCTION PHYSICAL PROPERTIES CHEMICAL PROPERTIES STRUCTURE TYPES OF DENTIN DENTINOGENESIS AGES CHANGES DEVELOPMENTAL ANOMALIES CLINICAL CONSIDERATIONS REFERENCES PULP INTRODUCTION MORPHOLOGY DEVELOPMENT OF PULP ZONES OF PULP CELLS IN PULP AGES CHANGES CLINICAL CONSIDERATIONS REFERENCES

3. Dentin and pulp are embryologically , histologically, and functionally the same tissue and therefore are considered as a complex Orbans (1980) stated that “ The pulp lives for the dentin and the dentin lives by the grace of the pulp. Few marriages in nature are marked by a greater interrelationship. Thus it is with the pulp and the four functions that it serves: namely, the formation and the nutrition of dentin and the innervation and defense of the tooth.” Based on this Nanci (2005) has stated that the pulp and dentin can no longer be studied as two separate entities but must be viewed as the pulp-dentin complex .

4. Hard tissue portion of the pulp-dentin complex the bulk of the tooth First formed Formation begins in late bell stage Formed by odontoblasts Bound to enamel at DEJ & to cementum at CEJ Consists of large no of small parallel tubules in a mineralized collagen matrix. Vital, nonliving DENTIN

5. HISTORY 1771 – JOHN HUNTER – hard tissue 1775 – ANTON VON LEEUWENHOEK – tubular structures 1837 – PURKINJE & RETZIUS explained about dentinal tubules CUVIEN gave the name IVORY to dentin 1891- VON EBNER GAVE THE TERM- ebners growth lines or imbrication lines 1906 – VON KROFF GAVE THE TERM – von kroffs fibres .

6. Physically and chemically the dentin resembles bone The main morphologic difference between bone & dentin

7. Physical properties

8. CHEMICAL COMPOSITION :

9. Organic component :

10. STRUCTURE OF DENTIN: Dentinal tubules : dentine is permeated by dentinal tubules. run from pulpal surface to DEJ & CEJ. tubules indicates the course taken by the odontoblasts during dentinogenesis . PRIMARY CURVATURE tubules follow an S- shaped path results from the crowding of & path followed by odontoblasts as they move towards the centre of the pulp. First curve towards apex, second towards crown In root dentin- little or no crowding- tubules run in a straight course

11. Dentinal Tubules Coronal dentin Root dentin

12. Secondary curvature of DT Secondary curvatures : tubules also show changes in direction of smaller amplitude(a few micrometers), observed under higher magnification.

13. Terminal branches: more profuse in root dentin than in coronal dentin . show a Y shaped terminal branching. Dentinal tubules are tapered shape larger near pulp- 2.5 µm in diameter smaller at DEJ- 1 µm or less TUBULE POPULATION : Approx ; 20000/mm² – towards DEJ 30000/mm²-75000/mm² – towards the pulp L ateral branches: tubules show lateral branches , almost 45 degree to main tubule, may contain O. Process, may communicate with adjacent ones or blindly end in intertubular dentin.

14. Lamina limitans Dental lymph Odontoblastic process Nerve fibers CONTENTS OF DENTINAL TUBULES :

15. ODONTOBLASTIC PROCESS Cytoplasmic extensions of odontoblasts larger in diameter near pulp- 3-4µm narrower near DEJ – 1 µm 3 hypothesis – pulpward migration of odontoblast as dentine is deposited :

16. ENAMEL SPINDLES:

17. Types of Dentin Dentin Primary physiologic dentin Secondary physiologic dentin Tertiary dentin or reparative dentin or reactionary dentin or irregular secondary dentin Mantle dentin Circumpulpal dentin Intratubular dentin Intertubular dentin

18. ( 1) MANTLE DENTINE First formed dentine in crown Underlying DEJ 20 µm thick Fibrils are perpendicular to DEJ Organic matrix – von korffs fibres (large dia fibrils-type III collagen fibrils) Less mineralized compared to circumpulpal dentine. Matrix vesicles involved in mineralization. Globular mineralization PRIMARY DENTINE Formed before root completion Consists of mantle dentine and circumpulpal dentine ( 2) CIRCUMPULPAL DENTINE : Circumpulpal dentin forms the remaining primary dentin or bulk of the tooth. The fibrils are much smaller in diameter (0.05micrometer) & are more closely packed together. Slightly more mineral content than mantle dentin.

19. SECONDARY DENTIN narrow band of dentin bordering the pulp forms after root formation is complete it is a slow continous deposition of dentin Contains fewer tubules than primary dentin It is formed more slowly than primary dentin TERITIARY DENTIN Reactive , Reparative, Irregular dentin. Produced in reaction to various stimuli. Quality and quantity depends on intensity and duration of stimulus. Tubules may or may not be present Cells may be included in dentin referred to as osteodentin .

20. STIMULI ODONTOBLASTS DIE FEW ODONTOBLAST SURVIVE MIGRATION OF UNDIFFERENCIATED CELLS FROM PULP TO DENTIN REPAIRATIVE DENTINE REACTIONARY DENTINE

21. Types Of Reparative Dentin Atubular dentin ( area without dentinal tubules) Osteodentin (entrapped cells ). Vasodentin (entrapped b.v .)

22. PERITUBULAR DENTIN Wall of dentinal tubules Highly mineralised Lost during decalcification overproduced – SCLEROTIC DENTIN Other name: INTRATUBULAR DENTIN : Depositon of the minerals occurs in the inner wall of the tubule rather on the outer wall, the term intratubular dentine is considered more appropriate. 15% more mineralized than intertubular dentin. Lacks collagenous fibrous matrix.

23. INTERTUBULAR DENTINE : Located between the dentinal tubules the primary end product of the odontoblasts . fibrils are arranged at roughly rt angles to the DT. FIBRILS 0.5 – O.2 micrometres in diameter. Less calcified Bulk of dentin Retained after decalcification

24. Dentinal tubules intratubular dentin Intertubular dentin

25. PREDENTIN located adjacent to the pulp tissue . is the mineralising front of the dentin. Always present throughout life. because mineralization process lags behind matrix deposition. 2 to 6 microns thick, depending on the activity of the odontoblast .

26. Interglobular dentin Areas of hypomineralized dentin where globular zones of mineralization ( calcosperites ) have failed to fuse into a homogenous mass within mature dentin. seen in the circumpulpal dentin just below the mantle dentin. The dentinal tubules pass uninterruptedly, thus demonstrating a defect of mineralization & not of matrix formation . Appear dark in transmitted light & bright under reflected light- ground sections.

27. GRANULAR LAYER : In root dentin adjacent to CDJ, when viewed under transmitted light in ground sections (LS) a granular layer can be seen. Caused by coalescing and looping of the terminal portions of the dentinal tubules HYALINE LAYER : Outside the granular layer is a clear hyaline layer. Upto 20µm wide Usually included as`a component of the dentine. May serve to bond cementum to dentine.

28. Structural lines in dentine 2 groups of lines: (1)lines associated with primary and secondary curvature of dentinal tubules. (a) S chreger lines (primary curvature) (b) contour lines of owen (secondary curvature) (2)lines arising from the incremental deposition of dentine and its subsequent mineralization. (a) i ncremental lines of von ebne r (short period lines) (b) A ndersons line (long period lines)

29. CONTOUR LINES OF OWEN: coincidence of the secondary curvatures between the neighbouring dentinal tubules . Some of the incremental lines are accentuated because of disturbances in the matrix and mineralization process. Seen in ground sections as hypocalcified bands. NEONATAL LINE : Represents an exxagerated contour line of owen & shows the changes in physiology(nutritional, hormonal, etc.) that occur at birth. Seen in primary teeth & the first permanent molars. Dentine distal to dis line(nearer to DEJ) - formed prior to birth & the dentine proximal to it(nearer to the pulp - formed after birth .

30. The incremental lines (von ebner ), or imbrication lines or short period line , appear as fine lines or striations in dentin . Seen as alternating dark & light bands. run at right angles to the dentinal tubules. R eflect the diurnal rhythm of dentine deposition as well as hesitation in the daily formative process. Cuspal dentine - 4µm/day (rapid deposition) Root dentine - 2µm/day (slower)

31. ANDERSONS LINES (long period lines) the term long period refers to the intrinsic temporal repeat interval that is greater than one day (in contrast to daily short period line). 16 - 20µm apart Between each long period line there are 6 – 10 pairs of short period lines. Cause for the 6 to 10 day periodicity is unknown.

32. AGE AND FUNCTIONAL CHANGES IN DENTINE 1. VITALITY OF DENTIN : Odontoblasts & its processes are an integral part of dentin. Reacts to physiologic and pathologic stimuli . As age advances , the ability of dentine to respond to stimuli decreases. 3. TERITIARY DENTIN : 2. SECONDARY DENTIN : The size of the pulp cavity decrease & obliteration of the pulp horns

33. 4. SCLEROTIC DENTIN : Dentinal tubules become occluded with calcified material. When this occurs in several tubules the dentin assumes a glassy appearance . Found specially in radicular dentin (apical 3 rd ). Transparent or light in transmitted and dark in reflected light.

34. 5. Dead tracts Tubules affected by caries may fill with bacteria odontoblast processes may disintegrate or retract Leaving behind an empty space- dead tract Dead tracts can occur due to death of odontoblasts from crowding (in pulpal horns). In ground sections appear black in transmitted light because they entrap air. Probably the initial step in the formation of sclerotic dentin

35. Dentinoenamel junction Its found in the form of series of scallops increases the adherence between dentin and enamel. More pronounced in coronal dentin where occlusal stress is more. Shape & nature prevents shearing of enamel

36. Dentino-cemental junction Firm attachment Smooth in permanent teeth Scalloped in primary teeth Intermediate zone- hyaline layer of hopewell smith- cements the cementum to dentin Product of HERS

37. DENTAL PAPILLA CELLS (LATE BELL STAGE) CYTODIFFERENCIATION OF ODONTOBLASTS DEPOSITION OF ORGANIC MATRIX MANTLE PREDENTIN APPEARS MINERALIZATION PHASE CIRCUMPULPA L DENTIN( PRIMARY DENTINE) ROOT DENTIN SECONDARY DENTINE DENTINOGENESIS Odontoblast Differentiation Matrix Formation Good Vascular Supply Mineralization Two phase mechanism:

38. Odontoblasts differentiation

39. Odontoblastic process formation At first more than one process As more D is laid down, the cells receed and leave single process.

40. Odontoblast become a protein forming and secreting cell. R E R , Mitochondria and Golgi bodies Ribonucleic acid and alkaline phosphatase Inner dental Predentin epith side Large open faced N R E R Mitochondria Golgi bodies

41. Matrix formation A- Mantle dentin The first formed dentin layer in crown And root Fibers are perpendicular to D E J Fibers are parallel to basement membrane

42. B) Circumpulpal dentin Mantle dentin Circumpulpal dentin. The fibers are parallel to DEJ ( right or oblique angle to DT) Crowding of the cells and appearance of junctional complex

43. MINERALIZATION PATTERN Histologically 2 patterns seen Globular calcification Linear calcification Globular calcification Deposition of crystals in discrete areas of matrix by heterogeneous capture in collagen globules enlarge & eventually fuse to form single calcified mass. as in mantle dentin formation Linear calcification Rate of formation slow- mineralization front apperas more uniform The process is said to be linear. Example- circumpulpal dentin

44. Mineralization Budding of matrix vesicles Rupture of matrix vesicles Mineralization of the mantle dentin Has membrane rich in alkaline phosphatase Calcium and phosphate ions undergo crystallization Matrix vesicle

45. DPP conc elevated - inhibits mineralization OSTEONECTIN – it can inhibit HA crystals growth & promote C a & phosphorous binding to collagen OSTEOPONTIN – promotes mineralization CHONDROITIN SULPHATE – properties vary depending on whether they are in: PREDENTINE- prevent transport and diffusion of crystals(inhibitors) MINERALIZING DENTINE - promote hydroxyapatite crystal formation.

46. ROOT DENTIN DEVELOPMENT Initiated by HERS Space btwn initial collagen fibres & HERS become filled with an amorphous ground substance with fibrillar non collagenous matrix secreated by root sheath(10µm). Collagen fibres laid down parallel to CEJ.

47. VASCULAR SUPPLY during dentinigenesis Good supply - imp during secretory phase Mantle dentin formation - capillaries are seen in subodontoblastic area. Circumpulpal dentin formation - capillaries migrate between odontoblasts and endothelium fenestrates . After dentinogenisis is completed - capillaries retreat and endothelial lining becomes continuous

48. DENTINOGENESIS IMPERFECTA DENTIN DISORDERS Autosomal dominant condition Type I & Type II: Tulip shaped teeth, bluish grey – yellow/brown. enamel chips off--- expose dentin, rapid attrition. Type III Amber appearance, excessive wear, multiple pulp exposures.

49. Dentin dysplasia : Regional odontodysplasia : - Maxillary anteriors affected. Delay or total failure in eruption. Irregular shape H/P: Reduction in amount of dentin widening of predentin layer large areas of interglobular dentine. irregular tubular pattern Rx: extraction and replacement by a prosthetic appliance ROOTLESS TOOTH Normal enamel Atypical dentin Abnormal pulp morphology Type I (RADICULAR) - coronal dentin normal - root dentin shows osteodentin , fused denticles , tubular dentin Type II (CORONAL) - multiple pulp stones in pulp - relatively normal coronal dentin.

50. DENTIN PERMEABILITY Depends upon patency of dentinal tubules Reduced permeability Decreased sensitivity Tubular occlusion Smear layer formation CLINICAL CONSIDERATIONS :

51. M I

52. CARIES OF THE DENTIN Histologically , 5 zones of early dentinal caries progression can be seen (listed pulpally to occlusally ):

53. Pit and fissure caries Follows the direction of dentinal tubules Triangular shape With base at DEJ and apex at the outer surface Greater no of dentinal tubules will be involved when the lesion reaches DEJ.

54. ADHESION OF DENTAL MATERIALS TO DENINE : SMEAR LAYER – when dentine is cut with a dental bur, a smear layer is formed consisting of dentine that has been melted & reset. ADVANTAGE: it occludes the dentinal tubules DISADVANTAGE: may harbour bacteria before applying bonding agents , the smear layer should be removed. Tags of resin in a restorative material(arrows) conforming to the dentinal tubules in etched dentine and enhancing retention of the restoratiion .

55. PULP has lost its odntoblast layer and is replaced by a vascular granulation tissue DENTINE is undergoing resorption by large multinucleated odontoclast – like cells

56. Radiograph of tooth showing external dentine resorption . The presence of radioopaque layer of dentine internally helps distinguish this case from one of internal dentine resorption .

57. OPERATIVE INSTRUMENTATION Dentin – treated with care during op.instrumentation to prevent damage to the odontoblasts AVOID EXCESSIVE CUTTING HEAT GENERATION CONTINUOUS DRYING USE AIR WATER COOLANT SHARP HAND INSTRUMENTS TUNGSTEN CARBIDE BURS to cut vital dentin- less heat generation

58. FORENSIC ODONTOLOGY IDENTIFICATION OF AN UNKNOWN CORPSE IN DISASTERS FROM DENTAL DNA: Tooth pulp – best source of dental DNA - DENTIN and cementum are also sources. - method- cryogenic grinding Long period( anderson ) lines in root dentine is used to calculate age at death . The extent of aspartic acid racemisation in dentin – a reliable marker for estimating age at death.

59. SMART DENTINE GRINDER STEPS: 1 - Extracting the tooth & Cleaning debris 2- Grinding the tooth with a specially designed grinder into particulate dentin 3- Cleaning particulate dentin by a chemical cleanser, resulting in bacteria-free bone graft 4- Grafting- The result is a particulate dentin two to three times the volume of the original root

60. Elephant   ivory  is solid dentin. The structure of the dentinal tubules contributes to both its  porosity  and its  elasticity . Elephant tusks are formed with a thin cap of enamel, which soon wears away, leaving the dentin exposed.

61. PULP The pulp is a soft connective tissue of mesenchymal origin residing within the pulp chamber and root canal of teeth (Cohen ).

62. Anatomy of Pulp Pulp Chamber or coronal pulp, located in the crown of the tooth . Root canal or radicular pulp, is the portion of the pulp located in the root area. The apical foramen is the opening from the pulp at the apex of the tooth. Accessory canals or lateral canal, extra canal located on the lateral portions of the root . Pulp horns

63.   LATERAL CANALS AND ACCESSORY CANALS According to the glossary of  American Association of  Endodontists , lateral and accessory canals are differentiated as Lateral canal Is a canal that is located at approximately at right angles to main root canal Accessory canal Is the one that branches off from main root canal,usually in the apical region of the root. Accessory foramina Are the openings of the accessory and lateral canals on the root surface Mechanism of formation accessory canals 1- it occurs in areas, where the developing root encounters a large blood vessel , where dentin will be formed around it. 2- Early degeneration of the epithelial HERS before the differentiation of the odontoblasts .

64. APICAL DELTA: It is a triangular area of root surrounded by the main canal, accesory canals and periradicular tissues. Difficult to instrument & obturate If not visible in radiograph, it may be left untreated. Recent thermoplasticized root canal filling- like obtura & thermofill obturate these variation more successfully .

65. DEVELOPMENT OF PULP: Begins at the 8 th week of embryonic life . Inner enamel epithelium ( Signalling molecules) Dental papilla cells undergoes cytodifferenciation into a peripheral layer of odontoblasts & central mass of fibroblasts Once odontoblasts have begun to lay down dentine Dental papilla becomes dental pulp

66. Small undifferenciated ectomesenchymal cells of dental papilla (less intercellular material) Synthetic organnelles appear, cytoplamic component of cells expands, Materials that the organelles produce is released into the extracellular space & forms the collagen fibres that are embedded in amorphous ground substance. 18 th week of IU Life nerve fibres are seen in dental papilla. Dental pulp cells during development produces nerve growth factors and semaphorin 7A & brain derived glial cell line derived neurotrophic factor. All these helps to innervate the pulp . Young dental papilla is highly vascularized during dentinogenesis .

67. FUNCTIONS OF PULP : INDUCTIVE Induce oral epithelial differentiation into dental lamina and enamel organ formation. Also induces developing enamel organ to become a particular type of tooth. FORMATIVE dentin NUTRITIVE Nourishes the dentin through the odontoblasts & their processes & by means of the blood vascular system of the pulp. PROTECTIVE Pulp helps in recognition of stimuli like heat ,cold, pressure & chemicals by way of sensory nerve fibres. Vasomotor innervation controls the muscular wall of blood vessels. This regulates blood volume & rate of blood flow & hence the intrapulpal P º.

68. DEFENSIVE Pulp has remarkable reparative abilities ,  It responds to irritation by producing reparative dentin  Mild to moderate irritation results in continued peritubular dentin formation, sclerosis and intratubular calcifiction -( Tubular sclerosis). Various cells of the pulp aid in the repair process. The rigid dentinal wall and the unyielding, enclosure can lead to partial or complete vascular collapse and necrosis of the pulp. However, if the inflammation is not too severe, the pulp will heal via its excellent regenerative properties.

69. PERIPHERAL ZONE (ODONTOGENIC ZONE). Zones of the pulp Dentin CENTRAL ZONE (PULP CORE)

70. Odontogenic zone: (1) odontoblasts : Location: A djacent to the predentin with the cell bodies in the pulp and cell processes in the dentinal tubules. Dentin

71. (2) Cell free zone (the zone of Weil ) : * It is present beneath the odontoblastic layer. * It is suggested to be the area of mobilization and replacement of odontobl asts . (3) cell rich zone: It is present beneath the cell free zone. It is composed of fibroblasts and undifferentiated mesenchymal ce lls .

72. PULP CORE : Central Co. T mass. Contains blood vessels & nerves embedded i n the pulp matrix with fibroblasts. Neurovascular bundles enter /exit this core through the apical foramen.

73. Cells of the pulp 2- Synthetic cells (formative cells): Odontoblasts and fibroblasts . Macrophages , lymphocytes, eosinophils , mast cells and plasma cells . 3- Defensive cells : 1- Progenitor cells : Undifferentiated mesenchymal cells .

74. 1- PROGENITOR CELLS: (UMC): They are smaller than fibroblasts but have a similar appearance. They are usually found along the walls of blood vessels. These cells have the potentiality of forming other types of formative or defensive cells.

75. Odontoblasts In the early stages of development odontoblasts consist of a single layer of columnar cells . In the later stages of development, the odontoblasts appeared pyriform where the broadest part of the cell contains the nucleus 2-FORMATIVE CELLS :

76. The cell membranes of adjacent odontoblasts exhibit junctional complexes. Gap junction desmosome coronal pulp- columnar midportion - cuboidal apical region–flattened

77. FIBROBLASTS * These are the most numerous type of pulp cells. * They are spindle in shape . * They have elongated processes which are link up with those of other pulpal fibroblasts ( stellate appearance . * The nucleus stains deep with basic dye and the cytoplasm is highly stained and homogenous .

78. These cells have a double function: formation and degradation of fibers and ground substances. In young pulp, they are : *Large cells . *With large multiple processes *Centrally located oval nucleus, *Numerous mitochondria, *Well developed Golgi bodies *Well developed RER mitochondria Fibroblast protein secreting cell

79. I n periods of less activity and aging they appear smaller and round or spindle-shaped with few organelles, they are termed fibrocytes . fibrocyte fibroblast

80. DEFENSIVE CELLS: HISTIOCYTE (MACROPHAGE): They appear irregular in shape with short blunt processes. The nucleus is small, more rounded & darker in staining than fibroblast. They are distributed around the odontoblasts and small blood vessels and capillaries.

81. In case of inflammation : *Nuclei increase in size and exhibit a prominent nucleolus. *It exhibits granules and vacuoles in their cytoplasm. Ultastructurally , invaginations of plasma membrane with aggregation of vesicles or phagosomes .

82. * Macrophages are involved in the elimination of dead cells. *Macrophages remove bacteria and interact with other inflammatory cells to protect the pulp during inflammation .

83. PLASMA CELLS: These cells are seen during inflammation . The nucleus of this cell is small and appears concentric in the cytoplasm. The arrangement of chromatin in the nucleus gives the cell a cart wheel appearance, The plasma cells are known to produce antibodies .

84. LYMPHOCYTES They are found in normal pulp and they increase during inflammation.

85. EOSINOPHILS They are found in normal pulp and they increase during inflammation .

86. MAST CELLS : * They have a round nucleus and their cytoplasm contains many granules . *They are demonstrated by using specific stains as toluidine blue . * They produce histamine& heparin .

87. Matrix FIBRE COLLAGEN ELASTIN FIBRONECTIN LAMILIN GROUND SUBSTANCE GAG PR OTEOGLYCAN

88. The ground substances of the pulp: * The ground substances consists of acid mucopolysaccharides and neutral glycoprotein. *These substances are the environment that promotes life of the cells. * Glycosaminoglycans are bulky molecules and hydrophilic, they form gels that fill most of the extracellular space, They contribute to the high tissue fluid pressure of the pulp.

89. FIBRES Mainly collagen fibre are type I and type III. These fibers form a loose, reticular network to support other structural elements of the pulp. Collagen is synthesized and secreted by odontoblasts and fibroblasts . In young pulp the fibers are relatively sparse throughout the pulp & gradually the bundles increase in size with advancing age.

90. Blood vessels * The pulp is highly vascularized. It is supplied by the inferior and superior alveolar arteries & also drain by the same veins. *arterioles enter the tooth- direct route to coronal pulp. *Along their course they give numerous branches in the radicular pulp that pass peripherally to form a plexus in the odontogenic region. D

91. Pulp vasculature

92. Nerves of the pulp The pulp has an abundant nerve supply which follows the distribution of the blood vessels. Two types of nerve fibers are present: *Sympathetic in nature. They control the contraction of the smooth muscles of the blood vessels. *Sensory nerves. Both contain myelinated and unmyelinated axons .

93. A-delta fibers Conduction velocity 2-30 m/s Lower threshold Involved in fast, sharp pain Stimulated by hydrodynamic stimuli Sensitive to ischemia C fibers Conduction velocity 0-2 m/s Higher threshold Involved in slow, dull pain Stimulated by direct pulp damage Sensitive to anesthetic s Dull pain Types and properties of pulpal sensory nerve fibers A-beta fibers Conduction velocity 30-70 m/s Very low threshold , non-noxious sensation 50% of myelinated fibers in pulp Functions not fully known Non- myelinated sympathetic fibers Conduction velocity 0-2 m/s Post- ganglionic fibers of superior cervical ganglion Vasoconstriction

94. * More nerve endings are found in the pulp horns than in other peripheral areas of the coronal or radicular pulp . * As the mylelinated nerves run coronally , they give off side branches and lose their myelin coat & form then sub- odontoblastic plexus of nerves known as plexus of Rashkow . Few axons extend in-between the odontoblasts to give the nerve endings .

95. Sensory response in the pulp cannot differentiate between heat, touch, pressure or chemicals. This is because the pulp organs lack those types of receptors. Heat, Touch, Pressure Chemicals Pain

96. Age changes in the pulp The size of the pulp The apical foramen The cellular elements The bl. vessels & n. Vitality . decreased

97. PATHOGENESIS OF PULP CALCIFICATIONS LOCAL METABOLIC DYSFUNCTION TRAUMA HYALINISATION OF INJURED CELLS VASCULAR DAMAGE (thrombosis) FIBROSIS MINERALISATION ( nidus formation) PULP STONES GROWTH WITH TIME

98. T ypes Pulp calcification localized ( pulp stones ) diffuse False denticle True denticle

99. True denticles They consist of irregular dentin containing traces of dentinal tubules and few odontoblasts . Remnants of the epithelial root sheath invade the pulp tissues causing UMC of the pulp to form this irregular type of dentin. Rare S mall in size. Found near the apical foramen False denticles Evidence of dystrophic calcification of the pulp tissue . No denti n al tubules & can exist in any area of the pulp. Formed of degenerated cells or areas of hemorrhage which act as a central nidus for calcification. Overdoses of vit . D , may favor the formation of numerous denticles .

100. Pulp stones are classified according to their location into: free, attached and embedded. *They continue to increase in size and in certain cases they fill up the pulp chamber completely. *If pulp stones come close enough to a nerve bundle pain may be elicited. *The close proximity of pulp stones to blood vessels may cause atrophy of it . free attached

101. Diffuse pulp calcification * Commonly occurs on top of hyaline degeneration in the root canal and not common in the pulp chamber. *They are irregular calcific deposition in the pulp tissue following the course of blood vessels or collagenous bundle. *Advancing age favors their development .

102. PULP IS A SMALL TISSUE WITH A BIG ISSUE!

103. CLINICAL CONSIDERATIONS : PULPITIS (PULPAL INFLAMMATION): Is a response of the traumatised pulp,with trauma being a result of a bacterial infection as in dental caries or physical trauma to the tooth structure.

104. Pulpitis : Etiology Dental caries Traumatic exposure. Marginal leakage. Cracked tooth Coronal fracture. Attrition. Abrasion. Invaginated odontome . Advanced periodontitis (periodontal-endodontic lesion

105. Pulp polyp (chronic hyperplastic pulpitis ) - endodontic treatment -extraction of the tooth

106.   CLINICAL SIGNIFICANCE OF APICAL FORAMEN: The apical constriction acts as a natural stop for the filling materials. Size and shape of the apical foramen should always be maintained. It should be neither enlarged nor blocked Care should be taken to prevent over instrumentation or extrusion of the root canal filling materials beyond the apex LATERAL & ACCESORY CANALS: Incidence of occurrence of lateral & accessory canals is high in human teeth, but the percentage of failures due to unfilled lateral canals is less. This is probably because of biological hard (dentin & cementum ) tissue closure of lateral assessory foramina .

107. Shape of the pulp chamber & its extensions into the cusps , pulpal horns is important. Wide pulp chamber in tooth of young person will make a deep cavity preparation hazardous. The pulpal horns project high into the cusps in younger ages exposure of pulp can occur If opening a pulp chamber for treatment, its size and variation in shape must be taken into consideration. With advancing age, pulp chamber becomes smaller , Pulp stones at the opening of root canal In anterior teeth coronal part of pulp chamber may be filled with secondary dentin. When the apical opening is at the side of the apex, not even radiographs will reveal true length of RC Difficult to locate root canals DURING OPERATIVE PROCEDURES

108. IMMEDIATE PULP EXPOSURE TO A HEALTHY TOOTH PORTIONS OF ODONTOBLASTIC LAYER,CELL FREE, CELL RICH LAYER & PULP PROPER ARE DESTROYED. BLOOD VESSELS & NERVE ARE CUT EXTRAVASATED RBCS & PLASMA CAUSES TISSUE EDEMA INCREASED INTERSTITIAL PRESSURE IN THE SURROUNDING PULPAL TISSUE AFTER 2 DAYS OF PULP CAPPING WITH CAOH EXPOSURE SITE CONTAINS A CLOT CLOT BECOMES REORGANIZED BY 5 DAYS , CLOT BECOMES PHAGOCYTOSED NEOANGIOGENESIS & FIBROBLASTS FORMS GRANULATION TISSUE FIBROBLASTS BECOME PARALLEL TO MEDICAMENT INTERFACE 7-9 DAYS , FIBROBLASTS ENLARGE , NOW THESE ODONTOBLAST LIKE CELLS ORIENT PERPENDICULAR TO THE PULP CAPPING MATERIAL BY 12 DAYS , REPAIRATIVE DENTIN IS FORMED.

109. HEALING AFTER CAVITY PREPARATION : CAVITY PREPARATION INJURES ODONTOBLASTS & OPENS D.TUBULES & DISPLACES NERVE & NERVE TERMINALS NEAR TO THE ODONTOBLASTS & ODONTOBLASTIC PROCESSES RAPID RELEASE OF NEUROPEPTIDES( SUBSTANCE P) IN THE VESICLES OF N.TERMINALS INFLAMMATORY CELLS RECRUITED TO THAT AREA, CELL RELEASE HISTAMINE, SEROTONIN & PROSTAGLANDINS JUNCTIONAL COMPLEX DISRUPTION ALLOW CA IONS INFLUX FROM DENTINAL FLUID INTO THE INJURED ODONTOBLAST INTRACELLULAR SPACES BECOME FILLED WITH FLUIDS & PROTEINS FROM PLASMA LEAKING FROM THE CAPILLARIES CLOTTING CASCADE INITIATED PREVENTS FURTHER INGRESS OF IRRITANTS TO THE DENTAL PULP

110. WITHIN ONE DAY, A SHALLOW CAVITY PREPARATION, ODONTOBLASTS REORGANISE & REESTABLISH THEIR PLASMA MEMBRANES THESES ODONTOBLASTS BEGIN TO SECREATE COLLAGEN & ECM COMPONENT AT 5 DAYS, GAP JUNCTIONS& TIGHT JUNCTIONS RESTABLISH BY 14 DAYS, INFLAMMATORY RESPONSE IS RESOLVED, ODONTOBLASTS CELL LAYER IS REESTABLISHED

111. PULPAL REACTION TO LASER PROCEDURE Laser use on soft / hard tissues has potential benefits of efficiency, reduced sensitivity, disinfection and precision. PULPAL REACTION TO ORTHOGNATHIC SURGERY Osteotomy of the jaw → Disruption in the blood supply Studies have shown that if a safe distance of 5 to 10 mm is maintained between the site of the surgery and the teeth, minimal disruption occurs. In most cases, the blood flow is regained within months of the surgery .

112. Orthodontic forces: pulpal cell damage , inflammation, vasodilatation. Orthodontic forces should be light and continuous, respecting physiologic boundaries. Care should be taken to ensure that the intended orthodontic tooth movement does not challenge the apical blood supply (e.g. compressing the root apex against the cortical plate).  Pulpal symptoms that arise during orthodontic treatment should be treated appropriately and swiftly.

113. References: B.K. B Berkovitz oral anatomy, histology and embryology, Fourth edition Ten cates , Oral histology , E ighth edition Orbans , oral histology and embryology , 13 th edition Shafers , textbook of oral pathology , seventh edition Oral development and histology , James K Avery, Third edition Textbook of endodontics , Nisha garg second edition Autogenous fresh demineralized tooth graft prepared at chairside for dental implant - Eun-Seok Kim Kim Maxillofacial Plastic and Reconstructive Surgery (2015) 37:8 DOI 10.1186/s40902-015-0009-1

114. caries Res.2006;40(3):256-64. Dentin-pulp complex responses to carious lesions. Lee YL, Liu J, Clarkson BH, Lin CP,  Godovikova V, Ritchie HH The dental pulp -Seltzer’s 3 rd edition Endodontics : Priciples and practices Torabine jad , Richard E 4 TH edition. Analysis of the inorganic component of autogenous tooth graft material Young kyun Kim, su gwan Kim & co workers journal of nanoscience and nanotechnology vol. 11, 7442-7445, 2011 Clinical application of auto-tooth bone graft Sung- min park & co workers J Korean Assoc `Oral Maxillofac Surg 2012;38:2-8. A longitudinal study of tooth growth in a single individual based on long & short period incremental markings in dentine & enamel. M. C. Dean & co workers International journal of osteoarcheology , vol 3: 249- 264(1993)

115. Extent of aspartic acid racemization in dentin: a possible marker for a more accurate determination of age at death. S. Ritz & co workers Z Rechtsmedizin (1990) 103; 457-46 2.