Structure of dentine

ALL ABOUT DENTIN

1. Structure of Dentin Presented by Dr. abhisek guria Dept . of conservative dentistry and endodontics

2. Contents Introduction History Dentinogenesis Formation of organic matrix Mineralization Odontoblast Odontoblastic process Odontoblastic biology Pre-odontoblasts Secretory odontoblasts Transitional odontoblasts Aged odontoblasts Matrix proteins influence mineralization

3. PATTERNS OF MINERALIZATION Globular pattern Linear patter Vascular supply Nerve supply Physical & chemical properties Chemical composition Organic component Inorganic component Structural components Primary curvatures Secondary curvatures Peri -odontoblastic space Lamina limitans Peritubular dentin Intertubular dentin

4. Predentin Primary dentin Secondary dentin Tertiary dentin Reactionary dentin Reparative dentin Interglobular dentin Granular layer Dentinoenamel junction Cementodentinal junction Enamel spindle Incremental lines Incremental lines of Von Ebner Lines of Schreger Contour line of Owen Neonetal line

5. Dentinal fluid Dentin permeability Age changes DEAD TRACTS DENTIN SCLEROSIS EBURNATED DENTIN Clinical considerations Hypersensitivity Direct neural stimulation theory Transduction theory Hydrodynamic theory Modulation theory Pulp dentin complex Dentinal caries

6. Infected and Affected Dentin Remaining dentin thickness Cavity preparation Operative Instrumentation Pulp protection Vital pulp therapy Indirect pulp capping Direct pulp capping Bonding to Dentin Dentin in Endodontics Apexification & apexogenesis Smear layer

7. Developemental anomalies Dentinogenesis imperfect Dentin dysplasia Regional odontodysplasia Dense in dente Tetracyclin staining Conclusion Referances

8. I NTRODUCTION Second layer of the tooth Structure that provides the bulk and general form of the tooth determines the shape of the crown, including the cusps and ridges closely resembles bone Said to be a living tissue

9. HIS T O R Y 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

10. DENTINOGENESIS

11. S T AGES Synthesis Of Organic matrix Subsequent Mineralization . Carried out by- ODONTOBLASTS

12. ODONTOBLASTS Cells Of Pulp, 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 .

13. ODONTOBLASTIC PROCESSES Cytoplasmic extensions of the odontoblasts Extend into the dentinal tubules largest in diameter near the pulp and taper further into dentin The odontoblast cell bodies are approx . 7µm in diameter & 40µm in length

14. ODONTOBLASTIC PROCESSES

15. ODONTOBLAST BIOLOGY PRE-ODONTOBLASTS SECRETORY ODONTOBLASTS TRANSITIONAL ODONTOBLASTS AGED ODONTOBLASTS

16. FORMATION OF PRIMARY DENTIN

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

18. 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 .

19. PATTERNS OF MINERALIZATION GLOBULAR(CALCOSPHERIC) pattern : 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 INTERGLOBULAR DENTIN RADIAL CRYSTAL GROWTH

20. LINEAR pattern when the rate of d entin formation occurs slowly m ineralization front appears more uniform – Circumpulpal Dentin 17

21. 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.

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

23. INNERVATION OF DENTIN Numerous Nerve Endings in Predentin and Inner Dentin. Closely Associated with Odontoblast Process. Arise from myelinated nerve fibers of Dental Pulp- (A δ fibres ) Reach Brain via Trigeminal N .

24. 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

25. CHEMICAL COMPOSITION BY VOLUME 45% 22% 33% BY WEIGHT 20% 15% 65% INO R G A NIC ORGANIC W A T E R

26. 1. ORGANIC COMPONENTS Collagen – 82% , MAINLY TYPE I and some Type III and V. Non Collagenous Matrix Proteins- 18% - Phosphoproteins - DPP(Phosphoryn), Gla-Protein . - G lycoproteins - Dentin Sialoprotein,Osteonectin , Osteocalcin - Proteoglycans - Chondroitin SO 4 (seen mainly in Predentin)

27. Enzymes - Acid Phosphatase, Alkaline Phosphatase. Lipids - phospholipids, glycolipids etc. in traces. Growth factors : Bone morphogenetic proteins (BMP) Insulin like growth factors (IGFs) Transforming growth factors β (TGF- β

28. 2. INORGANIC COMPONENTS 32 Calcium Hydroxyapatite: C a 10 (PO4) 6 (OH) 2 Thin plate like crystals, shorter than enamel. 3.5 nm thick, 100 nm long. Salts - calcium carbonate, sulphate, phosphate Trace Elements - Cu, Fe, F, Zn

29. STRUCTURAL COMPONENTS Od o ntoblast Process Dentinal Tubules Non mineralized matrix- Predentin Mineralized matrix- Peritubular and Intertubular Dentin.

30. DENTINAL TUBULES From pulp to DEJ resembles an S shape Ratio btwn outer and inner surfaces of dentine is about 5:1 Smaller branches- canaliculi -pathways of exchange M o re t u b u les p e r u n it a rea i n t h e cr o wn than in the root

31. 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 Tubule density/ unit area - ↑ toward pulp . No. of Tubules / unit area – crown> root.

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

33. SECONDARY CURVATURES At Increased Magnification- Secondary Curvatures.

34. PERI - ODONTOBLASTIC SPACE Potential space between tubule wall and od. Process. Contents - nerves, collagen fibrils, plasma proteins, glycoproteins and mitochondria.

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

36. PREDENTIN Located adjacent to the pulp tissues 2-6µm , depending on the activity of odontoblasts First formed dentin and is not mineralized Stains less intensely

37. PERITUBULAR DENTIN PERILUMINAL/ INTRATUBULAR DENTIN Immediately surrounds the dentinal tubules Collar - ↑ Calcified Matrix ↓ 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

38. INTERTUBULAR DENTIN Main Body Of Dentin. 1 Secretory Product. Less mineralized Hardness - 52KHN (Kinney et al 1996) The fibrils exhibit crossbanding at 64µm intervals

39. Dentinal Tubule Peritubular Dentin I n t ertubular Dentin 44

40. INTERGLOBULAR DENTIN Unmineralized islands - due to failure of fusion of mineral globules . In Circumpulpal Dentin Subjacent to pits and fissures. Tubules pass uninterrupted. Vitamin ‘D’ deficiency or Hypophosphatasia

41. TYPES OF DENTIN Primary dentin Mantle Circumpulpal Secondary dentin Tertiary dentin Reparative dentin Reactionary dentin

42. MANTLE CIRCUMPULPAL LOCATION Below DEJ B/n Mantle Dentin and Predentin. THICKNESS 20 µ 68 n m 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 PRIMA R Y DE N TIN (Prior To Root Completion)

43. P RIMARY DENTIN

44. M ANTLE DENTIN First layer of primary dentin under polarised light, mantle dentin ( RED Band ) can be differentiated from the Circumpulpal dentin ( Purple with black dentinal tubules) due to difference in collagen fibres in mantle dentin

45. CIRCUMPULPAL DENTIN After mantle dentin has been deposited M ajo r p a rt of p ri m a ry an d seco n d a ry dentin mineralised through calcospherites in the mineralisation front between predentin and mineralizing dentin

46. SECONDARY DENTIN after root completion Narrow band- bordering the pulp Deposited 1µ/day . Fewer tubules Bending of tubules at the 1 & 2° Dentin interface . great e r a m oun ts at roof of pulp chamber - protecting the pulp horns. 51

47. TERTIARY DENTIN Localized At pulp – in response to noxious stimuli Also known as: Reactive Dentin, Reparative Dentin, Irritation Dentin, Replacement Dentin, Adventitious Dentin, Defense Dentin No continuity with 1 or 2 Dentin so there is ↓ Dentin permeability. Quality Depends on : Intensity of stimulus. Vitality of pulp.

48. 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) 50 SMITH ET AL (1994)

49. REACTIONARY DENTIN REPARATIVE DENTIN Rate of deposition= 2.8-3 µ/day

50. GRANULAR LAYER OF TOMES In Root Dentin Increases in amt. from CEJ to Apex . Looping / coalescing of Dent. Tubules . Hypomineralized areas.

51. ENAMEL SPINDLES Odontoblast processes sometimes extend into the Enamel. Length is about 10 - 40  m near Incisal edges & cusp tips D ark in ground sections Hypomineralized Spread of Caries from Enamel to Dentin .

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

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

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

55. 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

56. 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 → sensitivity.

57. DEN T INO-CEM E N T AL JUNCTION Firm Attachment Smooth in Permanent teeth, scalloped in 1 o . Intermediate Zone- Hyaline layer Of Hopewell Smith- Cements the cementum to Dentin. Product Of HERS Apical Constriction - Termination of Instrumentation. 45

58. DENTINAL FLUID ( Dentin Lymph) Occupies space b/n dentinal tubule and od. Process . Ultrafiltrate - pulp Capillaries Ca content is 2-3 times higher than in plasma. Tissue pressure of pulp- 14 cm of H 2 O, (Ciucchi et al 1995) pressure gradient -tends to flow outwards slowly

59. Exposure of Tubules - Outward movement → dehydrating the surface-rapid flow of fluid - sensitivity . Slow outward flow of fluid ( 0.02 nl /sec/mm to 1-1.5.microlitre/sec/mm for nerves to begin firing. Acts as barrier for microbes and toxins .

60. 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.

61. 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

62. AGE AND FUNCTIONAL CHANGES Dead tracts Dentin sclerosis Eburnated dentin

63. DEAD TRACTS Empty Tubules Filled with air. Due to → Degeneration of odontoblastic process Black in transmitted light, WHITE IN REFLECTED LIGHT. Older Teeth - Areas of narrow pulp horns. ↓ sensitivity.

64. SCLEROTIC DENTIN Presence of irritating stimuli → 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

65. 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 . SCLEROTIC DENTIN

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

67. CLINICAL CONSIDERATIONS Hypersensitivity Pulp dentin complex Dentinal caries Infected and Affected Dentin Remaining dentin thickness Cavity preparation Operative Instrumentation Pulp protection Vital pulp therapy Bonding to Dentin Endodontics Smear layer

68. Hypersensitivity Unusual symptom of Pulp- Dentin Complex. It is a condition characterized by short , sharp pain arising from exposed dentin in response to stimuli typically thermal , evaporative , tactile, osmotic or chemical and which cannot be ascribed to any other form of dental defect or pathology . ( Holland et al 1997) Sharp Pain- easily localized. Eti o log y - Exposure of Dentinal tubules loss of enamel loss of cementum

69. DIRECT NEURAL STIMULATION By Scott Stella in 1963 Nerve endings in Tubules are Directly Activated by External Stimuli This view rests on the as s umpt i on t h at - Nerve fibres Extend to DEJ.

70. Drawbacks: No nerve endings in dentinal tubules Topical application of local anaesthetic agents do not abolish sensitivity

71. TRANSDUCTION THEORY By Thomas 1994 Odontoblastic Processes ar e primary structures excited by stimulus. Transmit impulse to Nerve Endings Supported by evidence that odontoblasts → Neural Crest Origin Drawbacks: No synaptic Contacts or vesicles - b/n odontoblasts and axons.

72. HYDRODYNAMIC THEORY Gysi (1900), Brannstrom Various stimuli heat, cold, airblast dessication or mechanical or osmotic pressure affect fluid movement in the dentinal tubules . Activating the Free Nerve Endings Associated with Odontoblast and its Process Act as Mechanoreceptors - Sensation is felt as pain.

73. Nerve impulses in the pulp are modulated through the liberation of polypeptides from the odontoblasts , when injured. Alter permeability of the odontoblastic cell membrane through hyperpolarisation , So that pulp neurons are more prone to discharge upon receipt of subsequent stimuli M ODULATION THEORY

74. Management - Block The Dentinal Tubules!!! Desensitising toothpastes - AgNo 3, SrCl 2, fluorides, Bonding Agents, lasers etc.

75. Suggestion for patients Avoid gingival recession due to plaque deposition by practicing good oral hygiene Avoid using large amount of dentifrice Avoid hard bristled tooth brushes Avoid brushing with excessive pressure Avoid excessive flossing or incorrect use Avoid picking at gums

76. Pulp dentin 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 .

77. Dentinal caries Zone1: Zone of fatty degeneration (from pulp) Zone2: DENTINAL sclerosis Zone3- Dentin decalcification Zone4: Decomposed dentin.

78. Remaining dentin thickness From base of the cavity to roof of pulp Methods of measurement Radiographic method CBCT Electrical resistance Prepometer RDT influence treatment outcome 1 mm of residual root dentine following post preparation is claimed to reduce the risk of root fracture Pulpal toxicity of certain materials ( eg zinc oxide eugenol) reduces with increasing dentine thickness

79. Bond strength of resin-based adhesive systems reduces as the dentine thickness reduces. Hydraulic conductance of radicular dentine decreases with increasing distance from the pulp Heat-induced pulpal injury following curing with light-emitting diode units or from burs during caries removal is more likely with reduced dentine thickness.

80. Minimal effects are transmitted to the pulp if RDT is 2mm or more. For an amalgam restoration 1- 2 mm is preferred. For a non metallic 0.5 – 1mm of dentin or liner / base is sufficient. Approxi m ately a 20 fold increa se is seen from extending a cavity preparation that is 3 mm from the pulp to 0.5 mm An acid etchant can increase permeability by 4- 5 folds as tubule apertures are enlarged.

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

82. Operative 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

83. Pulp protection Irritants from Restorative materials- pulp damage Need for pulp protection Mechanical protection Barrier to chemical components Thermal protection Galvanic protection Adequate seal at interface 71

84. 1 ) 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.

85. 2 ) CHEMICAL AGENTS: Alcohol &chloroform produce thermal irritation by evaporation and dehydrate dentinal tubules Hydrogen perox i de m ay t r avel th r ough dent i nal tubu l es into the pulp producing emboli and perhaps even arresting circulation. Dentin conditioning agents : widens the tubule increasing permeability.

86. 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 Anodyne effect through desensitization and blockage of pain impulse.

87. Thermal Protection- Bases below Restoration Base: materials that are used to replace missing dentin or to block out undercuts in preparation for indirect restorations. Chemical Protection- Cavity sealers, liners

88. Sealers : materials that provide protective coating to the walls of the prepared cavity. Eg : cavity varnish, resin bonding agent Liners : these are cement coating of minimal thickness, which serve as a physical barrier to bacteria Eg : calcium hydroxide, GIC

89. “Vital pulp therapy” The reparative Dentin Formation can be stimulated by cavity lining materials (such as Calcium hydroxide). Direct Indirect pulp capping Indirect pulp capping THE DENTINAL BRIDGE repair tissue that forms across the pulpal wound.

90. INDIRECT PULP CAPPING Definition A procedure wherein the deepest layer of the remaining affected carious dentin is covered with a layer of biocompatible material in order to prevent pulpal exposure and further trauma to pulp. Performed as single or two-step approach.

91. DIRECT PULP CAPPING DEFINITION : A procedure in which the exposed vital pulp is covered with a protective dressing or base placed directly over the site of exposure in an attempt to preserve the pulpal vitality .

92. IND I C A TIONS Iatrogenic mechanical exposure of pulp in an asymptomatic vital tooth Small carious exposures in an asymptomatic permanent tooth with an incomplete root formation. Radiographically no thickening of PDL space and no evidence of peri -radicular lesion.

93. CONTRAINDICATIONS Large carious exposures in symptomatic permanent tooth Materials used Calcium hydroxide Theracal MTA Biodentin

94. CALCIUM HYDROXIDE Pulpdent paste and Dycal HEALING WITH CALCIUM HYDROXIDE Zone of obliteration Zone of coagulation necrosis Zone of dentin bridge formation Line of demarcation

95. “Bonding to Dentin” Adhesion to Dentin… A CHALLENGE!! Due to - ↑organic content, tubular nature and presence of Fluid. Further complicated by “Smear Layer” It decreases dentinal permeability- but interferes with bonding SMEAR LAYER

96. 1949, Dr. Hagger , a Swiss chemist used first dental adhesive “ cavity seal ” Generations of bonding agent 1 st gen - 1956 Use glycerol-phosphoric acid & dimethacrylate (NPG GMA) Reduce bond strength 2 nd gen - 1970 formation of ionic bond between calcium and chlorophosphate groups Still fail to remove smear layer

97. 3 rd gen- Late 1970s Acid etching 4 th gen -1980s Total etch tech Etchant, primer, bonding agent Technique sensitive All bond 2, 3, scotchbond multipurpose 5 th gen - 1990s 1 bottle system (primer + adhesive) Excite, all bond plus, clearfill new bond

98. 6 th gen- early 2000s “self-etching primers”, 1 step 2 bottle (etchant& primer + adhesive) Lower bond strength Clearfil ac, g bond, adper scotchbond ac 7 th gen- early 2005 one-bottle self-etching system Reduced long term strength One coat 7.0, xeno iv, adper easy one 8 th gen- 2010 voco America introduced voco futurabond DC , contains nano fillers

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

100. APEXIFICATION Definition : Its defined as a method to induce a calcific barrier across an open apex of an immature, pulpless tooth. Objective formation of an apical “calcific barrier” against which obturation can be achieved. Apexogenesis Refers to a vital pulp therapy procedure to encourage physiological development and formation of root apex

101. 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] Has a potential to provide a media for recurrent caries and bacterial irritation of the pulp 2–5 lm thick

102. Methods of removal of smear layer Chelating agent EDTA Weak acid i.E. (10 % citric acid) Thorough canal rinsing with 3 to 5 % NAOCL. Ultrasonic removal with 1% Naocl Laser removal ( ne:yag , er:yag , co 2 laser)

103. DEVELOPMENTAL DEFECTS

104. 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.

105. TYPE I TYPE II TYPE III CLINICAL FEATURES T u l ip Sha p e d t ee t h, Bl u ish- grey- Yellow/Brown Translucent. Enamel Chips away→ Exposed dentin, rapid attrition. Amber appearance, Excessive wear, Multiple pulp Exposures. RADIO G RAP H IC FEATURES Partial/complete obliteration of pulp chamber , root canals Shell teeth- Normal Enamel, Thin Dentin, Huge pulp Chambers, short roots.

106. TREATMENT first ascertain which type he/she is dealing with. Severe cases of DI type 1 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.

107. Patients not exhibiting enamel fracturing and rapid wear crown placement and routine restorative techniques may be used. Bonding of veneers may be used to improve the esthetics. In more severe cases , where there is significant enamel fracturing and rapid dental wear, the treatment of choice is full coverage crowns.

108. 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.

109. 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

110. TYPE I(RADICULAR) TYPE II (CORONAL) CLINICAL FEATURES Normal Morphology, Amber Translucency. Extreme Mobility and Premature Exfoliation Primary - yellow /brown- grey. Permanent – normal. RADIOG R APHIC 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

111. Regional Odontodysplasia Maxillary Anteriors CLINICAL FEATURES : delay or failure of eruption, irregular shape. RADIOGRAPHIC FE A TURES : “ G h o st Teeth.”

112. T r e a tment: No treatment required Meticulous oral hygiene Extraction / Endodontic treatment Prosthetic rehabilitation

113. 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.

114. 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.

115. CONCLUSION…!!! Although dentin and pulp have different structures, once they are formed, they react to stimuli as a functional unit . Exposure of dentin through attrition, caries or trauma produces profound pulpal reactions that tend to reduce permeability and stimulate formation of additional dentin.

116. REFERENCES Orbans oral histology and embryology – 12 th edition Ten Cate’s Oral Histology- Development, structure and Function- Antonio Nanci - Sixth Edition. Pathways of the pulp- Cohen. Hargreaves- Ninth Edition. S h afe r ’ s T e x tbo o k o f Oral Pa tho l ogy - S h afe r , Hine, Lev y - 5 th Edition. Oral and Maxillofacial Pathology- Neville-3 rd Edition. The art and science of Operative dentistry- Theodore Sturdevant - 4 th Edition. An Atlas and Textbook of Oral Anatomy and Histology- Berkovitz . Tooth Wear and sensitivity Clinical Advances in restorative Dentistry-Martin Addy, Graham Embery, W Michael Edgar

117. Thank you!!!!