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dental cements

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dental cements traditionally used

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dental cements

  1. 1. Presented By :- Dr Aditya Shinde Guided By :- Dr Lalitagauri Mandke Presented By :- Dr Aditya Shinde Guided By :- Dr Lalitagauri Mandke (1-71)
  2. 2. CONTENTS  Introduction  Definition  History  Ideal properties  Classification Based on Ingredients & Application (Craig) Based on Bonding Mechanism (William O'Brien) Based on Setting Reaction (Anusavice)  Silicate cement  Zinc phosphate cement Modification Fluoridated cement Copper cement Silicophosphate cement  Zinc polycarboxylate cement
  3. 3.  Zinc Oxide Eugenol cement Modification Reinforced Zinc Oxide Eugenol EBA  Calcium Hydroxide cement  Conclusions  References
  4. 4. INTRODUCTION In last 20 years there has been an explosion of different types of dental cements that have become available to practicing dentist ,many of them tailored for specialized types of restoration. In fact ,there are so many products to choose from the task ,can become confusing. Dental cements, in the recent years has become restricted to those materials which are employed to bond inlays, crowns, bridges, posts and facings in or on the tooth and to retain orthodontic bands and retainers, however secondary applications of these cements include cavity linings, bases and temporary fillings, endodontic sealer.
  5. 5.  These different applications make varying demands on manipulative properties, working and setting times, and resistance to mechanical breakdown and dissolution. Thus some materials are better suited to some application than others.  Many of these materials are supplied in powder/liquid form and set by an acid-base reaction, but this is not universally true.  As yet, there is no ideal dental cement. Each material must be used on its merits with knowledge of its limitations.
  7. 7. o A substance that hardens to act as a Base, Liner, Filling material or Adhesive to Bind Devices and Prosthesis To Tooth Structure To Each Other . (Anusavice)
  8. 8. Dental Cement TimelineDental Cement Timeline 1850 1900 2000 ZOE ZPSC PCC GI RC RMGI Compomer 1950 CH
  9. 9. History…  1873- Silicate cement by Fletcher  1873- Zinc oxide and clove oil by Chisolm  1879- Zinc phosphate cement by Dr Pierce  1930- Calcium hydroxide paste by Hermann  1968-Polycarboxilic cement by Dennis Smith  1971-Glass ionomer cement by Wilson and Kent
  10. 10. Ideal properties of dental cements  Should be strong and hard.  Able to protect pulp  Should be insoluble in saliva & liquids taken in mouth.  Should be dimensionally stable.  Should be adhesive .  Should be non porous .  Should be biocompatible and non irritant.  Co-efficient of thermal expansion should be equal to the tooth structure.  Should not be affected by thermal changes and moisture.  Should be easy to manipulate.
  11. 11.  Water based cements o Glass & Resin modified glass ionomer o Zinc Polyacrylate o Zinc Phosphate  Resin based cements o Composite & adhesive resin o Compomers  Oil based cements o Zinc Oxide Eugenol o Non Eugenol -Zinc Oxide
  12. 12. Water based cements 1) Glass & Resin modified glass ionomer cement : Class V restoration - Retention of- Conventional alloy based restoration Orthodontic bands Alumina or zirconia based all ceramic restoration - High strength bases - Long term provisional restoration 2) Zinc Polyacrylate: - Retention of -Conventional alloy restoration -Orthodontic bands -Pediatric stainless steel crown - High strength bases - Long term provisional restoration 3) Zinc phosphate : - Retention of- Conventional alloy based restoration -Orthodontic bands - High strength bases - Long term provisional restoration
  13. 13. Resin based cements 1. Composite & adhesive resin : - Bonding- Conventional alloy based restoration -Ceramic crowns, bridges ,veneers, inlays, onlays. - Post & cores - Retention of - Provisional restoration - Orthodontic bands 2. Compomers: - Bonded conventional alloy based restoration - Retention of - Alumina or zirconia based all ceramic restoration - Orthodontic bands - High strength bases
  14. 14. Oil Based Cements Zinc Oxide Eugenol : High strength bases Provisional restoration Root canal sealers Gingival tissue packs Surgical dressing Non Eugenol -Zinc Oxide: Provisional restoration Root canal sealers Gingival tissue packs Surgical dressing
  15. 15. Based on the bonding mechanism (Williams O'Brien. 2002 & Richard van Noort)  Phosphate based :  Zinc phosphate cement  Modified zinc phosphate cement  Fluoridated cement  Copper cement  Silicophosphate cement  Phenolate based :  Zinc oxide eugenol cement  Reinforced zinc oxide eugenol  EBA and other chelate cements  Calcium hydroxide chelate cement  Polycarboxylate based:  Zinc polycarboxylate cement  Glass ionomer cement  Methacrylate based:  Acrylic cements  BIS-GMA type cements
  16. 16. Classification based on setting reaction ( Skinners)  Acid Base Reaction – Zinc phosphate Zinc polycarboxylate Zinc oxide eugenol Glass ionomer cement  Light / Chemical activities  Polymerization and acid base reaction Resin modified glass ionomer cement  Compomer  Resin cement.
  17. 17. Classification (E.C. Combe 6th edition)  Acid base reaction cements. Zinc phosphate Zinc polycarboxylate Zinc oxide eugenol Silicate Glass ionomer cement  Polymerising materials Acrylic polymer Cyanoacrylates Dimethacrylate polymers Polymer ceramic composites  Other materials i) Calcium hydroxide ii) Guttapercha iii) Varnishes.
  18. 18. Silicates  Introduced in 1903 as anterior filling materials.  Silicates are attacked by oral fluids and in time degrade,  They may not be considered permanent restoration.  The uses of silicate cements diminished with the advent of composite resins and development of GIC.
  19. 19. Powder:  Silica  Alumina  Fluoride compounds  Calcium salts Fluoride Flux - To permit proper sintering of the other ingredients. Liquid :  Phosphoric acid  Water  Buffer salts
  20. 20. Setting Reaction Powder mixed with liquid Powder attacked by acid liquid releasing Ca, Al, Fl ions Metal ions precipitate as phosphate cement matrix inclusive of Fl salts
  21. 21. Advantages  It exhibit good esthetic qualities .  Anticariogenic property.  Analogues to topical applied fluoride solution. DisadvantagesDisadvantages It lacks stability in oral fluids with loss of esthetic qualitiesIt lacks stability in oral fluids with loss of esthetic qualities Rubber dam is essential for successful silicateRubber dam is essential for successful silicate restoration.restoration. Irritant to pulp.Irritant to pulp.
  22. 22. Zinc Phosphate cement  Introduced over a century ago It is the oldest luting cement.  Longest clinical track record to compare with newer systems.  Synonyms `Crown and Bridge’ and “Zinc oxyphosphate’
  23. 23. ZINC PHOSPHATE CEMENT COMPOSITION  POWDER Zinc Oxide - Principle Ingredient Magnesium Oxide - reduces the temp. of calcification process 2.10% aids in sintering. Oxides of Bismuth, Calcium or - Impact a smoothness to freshly mixed Barium Cement mass. In large quantities lengthen the S.T Silicon Dioxide - In active filler  LIQUID Phosphoric acid - 45-64% Reacts with ZnO Water - 30 – 55% Increases Rate of reaction Aluminum - 2.3% Essential to the cement forming reaction – Zinc - 0.9% Moderates reaction between powder and Liquid allows adequate working time
  24. 24. CLASSIFICATION (Anusavice 9th edition )  Type I -Fine grained for luting -Film thickness should be less than 25 um  Type II - - Medium grained for luting and filling - Film thickness should be more than 40um
  25. 25. Manipulation  Dispense the cement P/L :1.4 gm / 0.5 ml.  Divide the powder in one corner of the glass slab into increments depending on product.  Dispense the correct amount of liquid, to area of the slab away from the powder.  Add the powder to liquid in portions at 15 sec intervals for a mixing time 60-120 sec
  26. 26.  Mix it over a large area of the slab with a flexible metal spatula.  Test the consistency of the cement before adding the last portion of powder.  Only part of that portion of powder may be necessary to reach the desired consistency.  The cementing strings about one inch above the slab.
  27. 27.  NOTE : Powder liquid reactions ,an accelerated by the presence of heat (exothermic reaction)  Liquid consists of partially centralized dilute Phosphoric acid. .  When this liquid is exposed to a humid atmosphere, it will absorb water. Whereas exposure to dry air tends to result in a loss of water which will alter the property of cement.
  28. 28. Frozen Slab Technique  Practical way to increase the working time and reduce the setting time of zinc phosphate cement.  50% increased powder/liquid ratio.  Mixing in a frozen glass slab at 210 C.  Effective when multiple castings are to be cemented.  Excess of cement is easy to clean up .  But decrease in compressive strength.
  29. 29. SETTING REACTION  Exothermic reaction Powder & liquid mixed Phosphoric acid attacks the surface Release of zinc ions & reaction of Al with phosphoric acid Al & Zn ions react with phosphoric acid Zinc alumino phosphate gel and surrounds with un reacted particle Thus the set cement is a cored structure consisting primarily of un- reacted Zinc Oxide particles embedded in a cohesive amorphous matrix of zinc aluminophosphate. Water is critical to reaction.
  30. 30. Properties  Compressive strength -104 Mpa  Tensile strength -55 Mpa  Modulus of elasticity – 13.7Gpa ( stiff & resistance to deformity )  Retention is mechanical  At insertion PH at 2 min – 2 at 24 hrs – 5.5  Damage to pulp occurs during first few hrs of insertion. WT MT ST 5 min5 min 2.5 -8 min2.5 -8 min 1.5 -2 min1.5 -2 min
  31. 31. Advantages  Most popular for cast restorations  Adequate strength  Reasonable working time  Excess material can be easily removed  Acceptable effect over the dental pulp  Manipulation less critical than other cements. Disadvantages  Pulp irritation  Lack of antibacterial action  Brittleness  Lack of adhesion  Solubility in acid fluids
  32. 32. Variations in Zinc Phosphate Cement Fluoridated cement: o Small % of stannous fluoride. o Lower strength & higher solubility than zinc phosphate. o Fluoride release continues over long period & uptake. reduces enamel solubility ,increases harness. o This activity should reduce the incidence of enamel decalcification under orthodontic bands. o Used in orthodontic band cementation. Copper/Silver cement: o Consists of proportion of red or black cuprous oxide or copper salts or silver salts to zinc oxide powder. o Liquid same as conventional. o Used in past due to germicidal action. o Were discontinued due to staining of teeth.
  33. 33. Silicophosphate cement : Combination of zinc phosphate & silicate cement. Contains small amounts of mercury compounds. Composition: Silicate glass & minor amount of zinc oxide,13-25% fluoride Liquid contains 50% phosphoric acid,45% water,4-9% zinc, 2% Al. Advantages : Better & toughness than zinc phosphate. Fluoride release & degree of translucency. Lower solubility & better bonding. Disadvantages : Less satisfactory mixing & rheological properties Leading to higher film thickness & greater potential for pulp irritation. Used for cementation orthodontic bands & restoring non vital teeth
  34. 34. Zinc Polycarboxylate Cement  It is the 1st adhesive material developed in dentistry.  Advantages over the traditional ZnPO4 • Compatibility with pulpal tissue • Adhesion to tooth structure.
  35. 35. ZINC POLYCARBOXYLATE CEMENT  POWDER: (Same as zinc phosphate) -Zinc oxide – Main ingredient - Stannous oxide –Replaces magnesium oxide - Silica, Alumina or Bismuth - Filler - Stannous fluoride – 4.5% improves the manipulation, characteristics, strength. -Sodium fluoride - 1% Anticariogenic property  LIQUID - Aqueous solution of Polyacrylic acid - Co-polymer of acrylic acid - Other carboxylic acid ( itconic acid) – stabilizes the liquid
  36. 36. ZINC POLYCARBOXYLATE MANIPULATION:-  Mixed at a P/L of 1.5 :1  The consistency is creamy compared with that of zinc phosphate cements.  The correct consistency is found in a mix that is viscous but that will flow back under its own weight when drawn up with spatula.  Dispensing of the liquid should be done immediately before mixing to prevent evaporation of water and subsequent thickening.  The mixed cement should be used only till appears glossy on the surface. Once the surface becomes dull, the cement develops stringiness and the film thickness becomes too great to seat a casting completely.
  37. 37.  Non absorptive surface, such as glass slab or treated paper, will keep all the liquid available for the reaction and facilitate spatulation.  Polyacrylate cements should be mixed within 30-60 sec, with half to all of the powder incorporated at once to provide the max thickness.  The strength of the mixed cement is not compromised by this technique.
  38. 38. Setting Reaction Surface dissolution of particles by acid Release of Zn, Mg ,Sn ions Bind to polymer chain by OH group Reacts with carboxylic group Cross linking of polymer chain Amorphous gel particle with unreacted particle dispersed
  39. 39. Properties  Compressive strength – 55 -67 Mpa  Tensile strength –slightly higher than ZnPO4  Modulus of elasticity -2.4 – 4.4 Gpa (less stiffer & less brittle than ZnPo4 )  Low soluble in oral fluids than ZnPO4  Excellent biocompatibility with pulp 2.5 min2.5 minWTST MT 30-60 sec 6 -9 min6 -9 min
  40. 40. Advantages :  Low level of irritation  Good adhesion to tooth substances & alloys.  Good strength ,solubility & film thickness compare to zinc phosphate. Disadvantage  Need for accurate proportion, more critical manipulation  Lower compressive strength & greater visco- elasticity than zinc phosphate.  Short working time & need clean surface to use adhesion potential (technique sensitive).
  41. 41. Zinc Oxide Eugenol  Extensively used in dentistry since 1890’s .  Least irritant of all the dental materials.  Poor strength when compared to zinc phosphate.  It has sedative effect on exposed dentin.
  42. 42. ZINC OXIDE EUGENOL ZnOZnO PrincipalPrincipal IngredientIngredient White rosinWhite rosin BrittlenessBrittleness of setof set cementcement Zn acetateZn acetate AcceleratorAccelerator strength –strength – up to 1%up to 1% MgOMgO ModifierModifier Zn stearateZn stearate PlasticizerPlasticizer EugenolEugenol Reacts with ZnOReacts with ZnO Olive OilOlive Oil Plasticizer (85%Plasticizer (85% Eugenol)Eugenol) WaterWater InitiatorInitiator AceticAcetic acid/alcacid/alc oholohol To accelerateTo accelerate setting – about 1%setting – about 1% POWDER LIQUID
  43. 43. CLASSIFICATION (ADA Sp. No 30) Type IType I Used for Temporary cementationUsed for Temporary cementation Type IIType II Used for Long Term cementation ofUsed for Long Term cementation of fixed prosthesisfixed prosthesis Type IIIType III Temporary Filling/ ThermalTemporary Filling/ Thermal insulating baseinsulating base Type IVType IV Intermediate Restorations andIntermediate Restorations and Cavity linersCavity liners
  44. 44. ZINC OXIDE EUGENOL CEMENT MANIPULATION  Temporary cements (Type I) & Liners ( Type IV ) A typically two paste systems. Dispense equal lengths of the accelerators and base pastes on a paper pad / glass slab Continue mixing until a uniform colour is achieved.  Long term Zinc oxide Eugenol Cements (Type – II) A powder & liquid system. Shake the powder bottle gently, then dispense the powder with the supplied scoop and the liquid with a dropper. Mix on a glass slab or treated paper pad with a metal spatula. Incorporate the powder into the liquid all at once and mix for 30 sec.  Coat the patient’s lips and adjacent teeth with petroleum gel before application of the cement. Oil of orange is a solvent useful in removing set cement.
  45. 45. ZINC OXIDE EUGENOL  SETTING REACTION zinc dioxide hydrolysis zinc hydroxide eugenol zinc eugenol  Water is needed to initiate the reaction and it is also a by- product of the reaction. So the reaction proceeds more rapidly in a humid environment.  The setting reaction is also accelerated by the presence of zinc chelate dehydrate.  Acetic acid is a more active catalyst for the setting reaction than is water because it increases the formation rate of zinc hydroxide. High atmospheric temperature also accelerates.
  46. 46. Advantages:  Minimal pulp reaction.  Good sealing properties  Strength adequate for lining material & luting single restoration & retainers, with good retention form. Disadvantages:  Hydrolytic breakdown under exposure to oral fluids  Inflammatory reaction in soft tissue  potential allergic response  Minimal mechanical properties for luting  May soften & discolor
  47. 47. ZINC OXIDE EUGENOL Modifications of ZOE :  Resin Reinforced Zinc Oxide Eugenol Cement  EBA and other Chelate Cements
  48. 48. RESIN REINFORCED ZINC OXIDE EUGENOL CEMENT  COMPOSITION : POWDER : Zinc powder – 80.0% Poly methyl-methacrylate – 20.0%(bond to other components) Zinc stearate - traces (accelerator) Zinc acetate Thymol & hydroxyquinoline – traces (antimicrobial agent) LIQUID: Eugenol – 85% Olive oil – 15% -(as plasticizer ,masks irritating effect of eugenol).
  49. 49. PROPERTIES  Film thickness - 25-75 um  Compressive strength - 35-55 MPa  Tensile Strength - 4 MPa  Modulus of elasticity - 2-3000 MPa  Water immersion reduces the mechanical properties due to loss of eugenol.  Mechanical retention of crowns of ZOE cement is less than Zinc phosphate cements.  An 83.5% success rate was noted for polymer reinforced cement after 7 years. WTST MT 5 min7-9 min 2 min
  50. 50. EBA AND OTHER CHELATE CEMENTS COMPOSITION Powder  ZnO  Aluminium oxide/other mineral fillers – 20-30%  Polymeric reinforcing agent (poly methyl methacrylate)  Barium sulphate - radiopacity Liquid  O- ethoxy benzoic acid 50- 60%  Eugenol – Remaining part
  51. 51. PROPERTIES  Working time and setting time – 7-13 min.  Film thickness – 40-70 um  Tensile strength – 6-7 MPa  Modulus of elasticity – 5000 MPa  Shows visco -elastic properties with very low strength and large plastic deformation at slow rates of deformation at mouth temperatures (37 C)  This is why EBA cement retention values for orthodontic bands, although superior to those of other zinc oxide eugenol type materials, are considerably less than those of zinc phosphate cement.  Exposing EBA cements to moisture results in greater oral dissolution than with other cements.
  52. 52. ADVANTAGES • Easy manipulation • Long working time • Good flow characteristics & strength characteristics • minimal irritation to the pulp • Best suited to luting of restorations with good fit retention where there is no under stress and for cavity bases. DISADVANTAGES • More critical proportioning • Hydrolytic breakdown in oral fluids • Liability to plastic deformation • Less retention than zinc phosphate cements
  53. 53. Applications  Luting agent  Cavity bases
  54. 54. Non- Eugenol cement (Cavit)  A premixed non eugenol paste used for temporary restorations & cavity bases.  Contains – Zinc oxide Zinc sulphate Calcium sulphate Glycol acetate Poly vinyl acetate Triethanolamine Red pigments
  55. 55.  Setting reaction initiated by saliva & water.  Better sealing into cavity walls due to hydroscopic properties.  Minimum thickness of atleast 3 to 3.5 mm required.  It is not satisfactory material for cementation.  When inserted into dry cavity it creates negative pressure, causing aspiration of odontoblast leading to pain.  PH same as ZOE.
  56. 56. Calcium Hydroxide INTRODUCTION  It has multipurpose use though not used as permanent restorative material  Ca(OH)2 is a white odorless powder  Mixed with water or saline to a form a paste.  It is strongly alkaline with a PH of 12.5  It is classified as an astringent in Pharmacology.
  57. 57. HISTORY  In 1936 Hermann introduced Ca(OH)2 to promote healing in many clinical situations  The introduction of this material in the US was by Teuscher and Zander in 1938.  Successful pulpal healing using Ca(OH)2 is between 1934 & 1941.
  58. 58. CHARACTERISTICS OF Ca(OH)2  Molecular weight of 74.08.  Radiolucent  Specific Gravity of 2.34  PH 12.5 at 25 C  Very slightly soluble in water, soluble in glycerin syrup and acids.
  59. 59. MECHANISM OF ACTION  High alkaline PH(11-13) Causes neutralization of acids produced by microorganisms.  Antibacterial effect due to high PH.  Seals the dentinal tubules offering dentin protection.  Induces reparative dentin below existing dentin.  Biocompatibility & calcific barrier enabling to maintain pulp vitality.  Ca(OH)2 maintains a local state of alkaline by that is necessary for bone/dentin formation .
  60. 60.  On Vital dentin  Considerably reduces the permeability of exposed dentin for penetration of bacterial components towards the pulp.  This may be due to  Coagulation of proteins in dentinal tubules  Due to secondary dentin formation  It has an antibacterial effect
  61. 61.  On Carious Dentin Ca(OH)2 has a strong antibacterial effect on the contaminated soft carious dentin.  ON EXPOSED PULP Low grade irritation due to coagulative necrosis caused by Ca(OH)2 leading to hard tissue differentiation in the pulp to calcific barrier formation.
  62. 62. DIFFERENT FORMS OF Ca(OH)2 AVAILABLE 1) DRY POWDER Dry powder of Ca(OH)2 medicinal grade. Free from impurities and contaminants is available. The powder could be supplied as such or mixed to a paste with either distilled water or normal saline. Mixing with water or ortho ethoxy benzoic acid is avoided as the reaction is too fast for convenient clinical use. 2) LIQUIDS They are supplied in bottles. Resinous solution of Ca(OH)2 are used as liners. The combination or resin film with alkaline Ca(OH)2 provides a protective film having better physical integrity as well as chemical neutralizing capacity for acids.
  63. 63. 3) NON – SETTING PASTES They are supplied in Jar’s or inject able single paste system. In these materials, calcium hydroxide is not reacting with other ingredients of the paste. The other ingredients are only carriers and the availability of free Ca and OH ions from the preparation will be more.
  64. 64. 4) SETTING PASTE 1. Chemically Activated Ca(OH)2 paste system Base 1) Calcium hydroxide – 51% 2) Zinc oxide -9.23% 3) Zinc Stearate – 0.29% 4) Ethylene Toluene Sulphonamide -39.48% CATALYST  Titanium oxide – 45.1%  Calcium Tungstate -15.2%  Barium sulphate – 4%  Glycol salicylate – 35.7%
  65. 65. 2. Visible light activated Ca(OH)2 – Single paste system.  CaOH  BaSO4  UDMA Resin  Camphorquinous 5) SLOW SETTING Ca(OH)2 Pastes.  Root Canal Sealer materials  Ca(OH)2 can be used as a sealer to coat the Would of the pulp space and form a hermetic seal Ex – Calcibiotic  Root Canal Sealer paste (CRCS Paste)  Containing – ZOE, Ca(OH)2
  66. 66. VEHICLES When CaOH2 powder is mixed with a suitable vehicle a paste is formed. The vehicles play a major role in the over all process because it determines the velocity of ionic dissociation causing the paste to re-establish and restore at various rates by the peri apical tissues within the root canal. Types of Vehicles are used  Aqueous Vehicles – Water Saline LA solution  Viscous Vehicles - Glycerine Polyethyl glycol  Oily vehicles - Olive Oil Fatty acids. Eugenol.
  67. 67. Direct PulpDirect Pulp CappingCapping Indirect Pulp CappingIndirect Pulp Capping BaseBase PulpotomyPulpotomy LinerLiner Root canal sealerRoot canal sealer Prevention & treatment of ResorptionPrevention & treatment of Resorption Repair in perforationRepair in perforation Intra Canal MedicamentIntra Canal Medicament Horizontal #Horizontal # Root fractureRoot fracture ApexificationApexification CALCIUM HYDROXIDECALCIUM HYDROXIDECalcium Hydroxide
  68. 68. Adverse Effects  Calcifications in pulp.  Internal resorption.  Ankylosis.  Increased brittleness of dentin.
  69. 69. Summary  Zinc phosphate cement has long served as the universal luting cement. Its advantages includes good handling characteristics and a proven longevity in the oral cavity when it is used for cementation of well designed and well fitting restorations.  Its disadvantages include pulp irritation, lack of adhesiveness to tooth structure, and lack of anticariogenic properties. ZnPO4 is not suitable when the mechanical retention poor or when the aesthetic demand is high.  The main advantage of improved Zinc Oxide Eugenol cement is their biocompatibility. The physical and mechanical properties and the handling characteristics generally inferior to those of other long term luting cements.
  70. 70.  The properties of zinc Polycaroxylate cement are good compared with those of ZnPO4. The outstanding characteristics are their blandness to the pulp and formation of an adhesive bond to tooth structure.  Disadvantages include the short WT, SF and limited capabiling for fluoride release. Their short W.T limits their used to single units or three unit fixed partial dentures (bridges). These cements have decreased in popularity, but they are still often used for patients who have reported a history of postoperative sensitivity.  Calcium hydroxide is not a restorative material by itself many a time , but forms a part of restoration. Its fascinating osteogenic & dentinogenic potential have elevated its status as unique material used in dentistry.
  71. 71. REFERENCES  Theodore M. Roberson: Sturdevant’s Art and Science of Operative Dentistry 4th & 5th edition.  Skinners  Kennith J Anusavice: Phillips’ Science of Dental Materials 11th edition & 9th edition.  S Mahalaxmi : Materials used in dentistry,2013.  Robert G. Craig and John. M: Restorative Dental Materials 11th edition & 12th edition.  Joyre Reese , Thomas Valege :Restorative Dental Materials :An Overview, 2nd edition  Williams O'Brien. 2002 & Richard van Noort  E C Combe 6th edition.