Ceramics

• 1. All-Ceramics&Recent advances

2. contents1.INTRODUCTION2.EVOLUTION & HISTORY3.METHODS TO STRENGTHEN PORCELAIN4.ALLUMINOUS CORE PORCELAIN5.IN-CERAM6.CASTABLE CERAMICS7.MACHINABLE CERAMICS8.SCOPE OF ALL CERAMICS9.CONCLUSION10.REFERENCES 3. INTRODUCTION 4. DEFINITIONSCeramics : compounds of one or more metals with a non metallic element(usuallysilicon,boron,oxygen) that may be used as a single structural component or as one ofthe several layers that are used in the fabrication of a ceramic based prosthesis .(G.P.T 7, Anusavice)Porcelain : a ceramic material formed of infusible elements joined by lower fusingmaterials.Most dental porcelains are glasses and are used in fabrication of teeth fordentures, pontics & facings, crowns, inlays, onlays and other restorations. (G.P.T 7)Ceramic is derived from Sanskrit word meaning Burnt earth 5. 5 Formulated to provide: Castability, Moldability, Injectability, Color, Opacity, Translucency, Machinability, Abrasion resistance, Strength, Toughness. 6. HISTORY&EVOLUTION OFCERAMICS 7. Denture teeth&Dentures -Duchateau 1774Ceramic paintings and Vases 8. 1887 PJC CH. Land (platinum foil technique)1962 PFM Weinstein1965 McLean and Hughes aluminium core porcelain1957 Vines and Sommelman Vaccum firing1940 with advent of acrylics PJC lost popularity. 9. Evolution of all ceramic restorations : 1887 CH. Land gave porcelain jacket crown 1965 - McLean and hughes aluminous core porcelain 1980 - in ceram-slip casting, castable ceramics Latest 1990s - machinable ceramics(CADCAM) 10. 10CLASSIFICATION OF DENTALCERAMICS1) USE/INDICATION: Anterior, Posterior, crowns,veneers, post and cores, stain and glaze ceramic.2) COMPOSITION: pure alumina, pure zirconia,silica glass, leucite based glass, Lithia basedglass.3) PROCESSING METHOD: sintering, partialsintering, glass infiltration, CAD-CAM, copymilling, condensation, heat pressing, casting, slip-casting. 11. 114) FIRING TEMPERATURE:HIGH FUSING : 1300 CMEDIUM FUSING : 1101-1300 CLOW FUSING : 850-1100 CULTRA LOW FUSING: < 850 C5) MICROSTRUCTURE: glass, crystalline, crystal-containing glass 12. 126) TRANSLUCENCY:Opaque, Translucent, Transparent7) FRACTURE RESISTANCE8) ABRASIVENESS 13. 13 Three main divisions of ceramics:1. Predominantly glassy materials,2. Particle filled glasses---- Glass ceramics3. Polycrystalline ceramics. Esthetic dental ceramics : Glassy Substructure dental ceramics: Crystalline 14. 14 Best mimic the optical properties of enamel anddentine: Glassy material Glasses: 3D network of atoms having no regularpattern to the spacing between nearestatoms, thus they are amorphous or without form. Derived principally from a group of minedminerals called FELDSPAR: based on silica andalumina: Aluminosilicate glasses. Resistant to crystallization during firing, longfiring ranges, biocompatible. 15. 15 Filler particles are added to the base glasscomposition to improve mechanical propertiesand to control optical effects likeOpalescence, Color, Opacity. Fillers: Crystalline/Higher melting glass Leucite: first fillers to be used, crystalline mineral Feldspar forms crystalline mineral Leucite, whenmixed with metal oxides & fired to hightemperature Leucite is potassium-aluminum-silicate mineralwith large coefficient of thermal expansion. 16. 16 This filler was added to create porcelains thatcould be successfully fired on metal susbstruct. Adding 17-25% Leucite filler to base glasscreates porcelains that are thermally compatiblewith dental alloys.- Index of refraction close to feldspar,- Selective etching Moderate strength increases can also beachieved with appropriate fillers added anduniformly dispersed: Dispersion Strengthening 17. 17 Special subset of particle-filled glass The crystalline filler particles are grown insidethe glass object (pellet/prosthesis) by a specialheat treatment that causes the precipitationwithin the glass. This crystal nucleation and crystal growthprocess is called Ceramming. E.g. Dicor: crystalline mica: 55 vol% Empress 2: lithium disilicate : 70 vol% 18. 18 No glassy components, atoms are denselypacked, regular network: Crack propagationdifficult. Tougher and stronger than glassy ceramics. Difficult to process, CAD-CAM. Relatively opaque, core substructure. E.g. Aluminum oxide, partially stabilized Zirconia. Procera, Cercon, Lava. 19. COMPOSITION OF DENTALPORCELAINS:Composition (Percentage) Use- Feldspar 60-80% Basic glassformer- Quartz 15-25% Filler- Oxide 9-15% Fluxes- Alumina 8-20% Glass former &fluxes-Metallicpigments1% Color matching- Kaolin 3-5% Binder 20. High Fusing Porcelains:Feldspar - 70-90%Quartz - 11-18%Kaolin - 1-10%Medium Fusing Low FusingSilica dioxide 69.4% 64.2%Boric oxide 7.5% 2.8%Calcium oxide 1.9%Potassium oxide 8.3% 8.2%Aluminium oxide 4.8% 1.9%Lithium oxide - 2.1%Magnesiumoxide0.5%Medium & low fusing porcelain 21. Individual ComponentsPotash feldspar - K2O Al2O36SiO2Soda feldspar - Na2O Al2O3 6 SiO2Silica SiO2Crystalline quartzCrystalline cristobaliteCrystalline tridymiteNon-crystalline fused silica- it acts as arefractory skeleton provides strength andhardness. 22. Glass modifiers: Boric oxide B2O3Function:Lowers fusion temperatureIncreases flow of porcelainRemoves impuritiesHelp to produce dental porcelain withdifferent firing temperatureActs as a flux, by interrupting theintegrity of the silica network. 23. Kaolin:Acts as a binderAlso imparts opacityAlumina: Forms a network in conjunction with silica.Alters softening viscosity.Metallic Pigments: Pigment oxidesHelp to obtain various shades needed to stimulate naturalteeth.Brown - Iron or nickel oxideGreen - Copper oxideYellow brown - Titanium oxideBlue - Cobalt oxidePink - Chromium tin or chromaOpacity is achieved by addition of :-Cerium oxideZirconium oxideTitanium oxideTin oxide 24. 24 Excellent Flexural Strength,- Glazed : 141.1 MPa - Unglazed: 75.8 MPa Compressive strength: 331 MPa Tensile strength: 34 MPa Shear strength: 110 MPa Modulus of elasticity: 69 GPa Surface hardness: 460 KHN 25. 25 CorrosionResistance, Chemicalcorrosion. 26. 26 Less Reactivity ; Chemical Inertness Brittle Fracture, Low fracture toughness, Biocompatibility, Color Stability, Refractory Nature, High Hardness, Low Thermal Conductivity, Diffusibility andElectrical Conductivity. 27. Advantages of porcelainHigh abrasion resistanceChemical inertnessExcellent thermal and electrical insulatorsExcellent esthetic qualitsTranslucencyColor stabilityCapacity of pigmentationStain resistanceEnhanced polishabilityHigh durable 28. Disadvantages of porcelainHighly brittleExcessive wear of opposing teethHigh firing shrinkageMethods used to overcome the deficiencies ofceramics fall under 2 categories:-Methods of strengthening brittle materialsMethods of designing components to minimizestress concentration and tensile stress 29. METHODSTOSTRENGTHENPORCELAIN 30. Griffiths Flaw Crack GrowthSintering ProcessWhy are Ceramics weak ?On moisture exposure crack growth is accelerated1. Brittle Covalent bonds2. Inherent flaws3. > # in moist environment 31. Methods of Strengthening:-Development of residual compressive stresses within thesurface of the material.Interruption of crack propagation.Minimizing tensile stressesAvoiding stress concentration1) Development of residual stresses:Strengthening is gained by virtue of fact that these residualstresses must be first be negated by developing tensilestresses before any net tensile stress develops.. Principle:Strengthening is gained by the fact that the residualstresses must be first negated by the developing tensilestress before any net tensile stress develops.E.g. Normal tensile strength : + 60 MPaResidual comp. stress : - 40 MPaTotal tensile stress to induce fracture: + 100 MP 32. Methods:1) Ion-exchange: (Chemical Tempering)Involves exchange of large potassium ions for thesmaller sodium ions.Sodium containing glass articles is placed in a bath ofmolten potassium nitrate.The potassium ion is 35% larger than sodium ion.Squeezing of the potassium ions into the place of sodiumions creates a large residual compressive stress 33. 2.Thermal Tempering:-Most common methods.Thermal tempering creates residual stresses by rapidlycooling (quenching). The surface of object while it is hotand in the softened (molten) state.This rapid cooling produces a skin of rigid glasssurrounding a soft (molten core).As molten core solidifies it tends to shrink, createsresidual tensile stresses within the outer surface.Mismatch Coefficient of Thermal Expansion:-The metal and the porcelain used for the restoration aredesigned with slight mismatch in their co-efficient ofthermal expansion.The coefficient of thermal expansion for metals is morethan porcelain thus the metal contacts more than theporcelain on cooling provides additional strength. 34. Interruption of Crack Propagation:Methods: Dispersion a crystalline phaseAluminous Porcelains (PJC): Alumina which isa tough crystalline material is added to a glassin the particulate form, the glass is toughenedas the cracks cannot penetrate the aluminaparticles.Dicor Castable Glass Ceramics): Dicor utilizesinhibition of crack prepagation by the growth ofmica crystals in the ceramic as a result of heattreatment of the ceramic. Mica crystals in situinterrupt crack propagation their bystrengthening the restoration.. 35. Transformation Toughening:New technique of strengthening glasses. Strengtheningglasses involves the incorporation of crystalline materialthat is capable of undergoing a change in crystalstructure when placed under stress.The crystalline material partially stabilized Zirconia.The energy required for the transformation of is takenfrom the energy that allows to crack to propagateInvolves transformation of ZrO2 from a TETRAGONALphase to a MONOCLINIC phase at the tips of cracks thatare in the region of tensile stress. 36. 36 37. Designed in such a way to overcome weakness. To avoid exposure of the ceramic to high tensilestresses. To avoid stress concentration at sharp angles. Minimizing Tensile Stresses: High tensile stresses Posterior segment of mouth Deep overbite in the anterior region A ductile metal coping prevents the formation of Tensilestresses in the porcelain and prevents it failure.Reducing Stress Raisers: Stress raisers are discontinuities in ceramicstructures and in the brittle materials that cause stressconcentration. 38. Methods of strengthening brittle materials1.Ion exchange2.Thermal tempering3.Thermal compatiabilityMinimise stress concentration1. Reducing stress raisers2. Minimise tensile stressesResidual compressivestressesInterruption of crackpropagationAddition ofdispersion phaseChange in crystallinestructureParticle stabilizedzirconiaToughness ofparticleAl, dicor 39. Processing procedure 40. 2 Options1. Strong Core ( Unaesthetic )Layered with Veneering Porcelain2. Esthetic as well asstrong Core 41. Coping are prepared by Electrodeposition of metal on duplicate die Burnishing & heat treating metal foil on a die Cad cam Casting pure metal by lost wax tecnique Bonding of metal to ceramic, the ceramic musthave : Fusion temp well above its sintering temp Co efficient of thermal contraction closely matched tothat of the alloys. Metal oxide on the metal is necessary for bonding 42. Porcelain condensation Careful cleaning metal frame work and thin layer ofopaque porcelain is applied and baked. Dentin porcelain powder in the shade selected forbody/dentine portion. Porcelain is supplied in powder & mixed with water andcondensed into desired. To achieve thorough condensation, 3 methods are used Mild vibration Cleaned excess water by tissue paper Use brush to add dry powder to absorb excess water. 43. Firing/ Sintering of porcelain Porcelain restoration are fired either by temperaturecontrol alone or temperature or time control. Sintering is defined as a process of heating withoutmelting closely packed particles to form a cohert massby inter-particle bonding and sufficient diffusion todecrease the surface area and increase the density ofthe structure. 44. The aim of glazing is to seal the open pores in thesurface of a fired porcelain. Dental glazes are composedof colorless glass powder, applied to the fired crownsurface, so as to produce a glossy surface. Porcelain is cleaned and necessary stains applied. Glazing is short, when glazing temperature is reached,on thin glassy film (glaze) is formed by viscous flow onthe porcelain surface. Fracture resistance of glazed porcelain is greater thanunglazed porcelain 45. Metal reinforced systems 46. CAPTEK SYSTEM : ( capillary casting technique)Duplicated refractory dieMetalimpregnatedwax sheetFinal copingPorcelain veneeringCAPTEK is the answer for the most challenging situation because ofits strength and excellent estheticsCaptek G-97.5 gold,2.5 silverPt-pd 47. (HELIO FORM HF 600 SYSTEM)Equipment Polyurethane diesCompleted restorationsELECTRO FORMED 48. 1965 Mc lean and Hughes40 t0 50 wt% of Al2O3Flexural strength 131 MpaPlatinum foil techniqueALUMINOUS CORE PORCELAINFinished CoresMaster modelwith dies Platinum foiladapted to die(Hi-Ceram) 49. Unsintered CrownsDentin CeramicadditionsFinished Crowns on diesPost-CementationMc lean 1979 Five year failure rate 2% for anteriors 15% for posteriorsLarge sintering shrinkageSeiber et al 1981 :light reflection better than porcelain fused to metal 50. IN-CERAMA process used to form green ceramic shape by applying aslurry of ceramic particles and water or a special liquid to a poroussubstrate Such as a die material, there by allowing capillary actionto remove water and densify the mass of deposited particlesFlexuralstrength350 MPa 500 MPa 700 MPaIn-ceramAluminaIn-ceramSpinellIn-ceramZirconiaCrack deflection is the main Phenomenon( Slip casting technique )Saadoun 1989 51. Al2O3 slip Glass infiltrationVita Inceramat3Giordono 1995 : Al2O3 Core glass infiltrated Ceramic > Strength thanHi-Ceram, Di-Cor & Feldspathic PorcelainVaccumat 4000 Premium 52. DuplicationIn-Ceramrefractory diesIn-CeramapplicationAl2O3 slip10 hrs 1120 c- 2hrsvita inceramatWorking modelGlass infiltration4hrs 1100cShrinkage of dies 53. Application of bodyand incisal porcelainPostoperative veiw ofIn-Ceram crownsFinished In-Ceramcopings(Air abraded)Finished crownsPreoperative veiwProbster et al : Strength of In-Ceram > IPS Empress < PFM 54. CASTABLE CERAMICS 55. CASTABLE CERAMICSA glass ceramic material that combines the properties of arestorative material for function with the capability to be castusing the lost wax process Di-Cor Cerestore IPS Empress New typesCera pearlCanasite glass ceramicOptimal pressable ceramicOlympus castable ceramicsCastable phosphate glass ceramic1968 Mc Culloch 56. DI-CORNon porous, homogenous, microstructure with uniformcrystal size which is derived from the controlled growth of crystalswithin an amorphous matrix of glass.Ancestry Fredrick carter corning glass worksComposition : SiO2, K2O and MgO, MgF2, Al2O3, ZrO2 andflourescing agent TETRA SILICIC FLUOROMICA GLASSCERAMIC.Mica crystals Feldspathic porcelain 57. Wax patternSpruingInvestingBurnoutDivestingCast glass copingCeramming1750 for 12hr450 for 12 hrCentrifugal casting2600 f 58. Ceramming Ceramming oven Crystallised glass copingConventional porcelain application & Firing Finished crownCerramming done from room temparature- 1900 f for 1 hrs andsustained for 6hrs inorder to form tetra silicic flouro mica crystals 59. Properties :Flexural strength 81 6.8 MpaMarginal adaptation :Weaver et al 1988 conducted a study on 10 dicor crownsMarginal opening 57 9 mDue to less seating pressure, increase in density of ceramicafter ceramming.Biocompatibility :Less bacterial countsReason : smooth surface, low surface tension, flouride content,Low thermal conductivity 60. Esthetics :Gross man and adiar : Hue and chroma of metal ceramicsand castable ceramics matched natural teeth.Value of only castable ceramics matched natural teeth.Presence of mica crystals scatter light similar to enamel rods.Cementation :zinc phosphate, light activated urethane resinBailey&Bennet 1988 etching with ammonium biflouride for 2 min 61. Survival rate :Kenneth et al 1999 14yr studyCrowns 82%Cores 100%Inlay and onlay 90%Partial coverage 92%Posterior 70% anterior 82.7% Expenstein et al 2000 62. CERESTORE(SHRINK FREE CERAMICS)Chemistry :Binder silicone SiO SiO2Unfired cerestore core :Al2O3MgOGlass fritSilicone resinFillersAl2O3 + MgO MgAl2O4 + CorrundumStrength160-1800CFired cerestore core :- Al2O3 (Corundun)MgAl2O4 (Spinel)Ba Mg2Al3 (Si9Al2O30) Bariumosumilite 63. TECHNIQUE :Tooth preparation :1.25 1.5 mm (Labial-lingual,interproximal)1.5 2.mm (occlusal)900 (full shoulder ) Conventional wax-up onheat stable Epoxy diesInvesting Ceramic pellet in flask for pressing160 c 64. Ceramic injected into moldPlaster removal frompressed copingRefining green statecopingCoping on master die firedat 1300 c 65. Tooth preparation and impressionCerestore epoxy dieWax up and invest with master dieBoil outHeat flask to 1800CTransfer mould ceramic into lost waxcavity directly on master dieRetrieve master dieRefine coping, add veneer porcelain 66. Properties : Flexural strength : 225 Mpa Fit : exceptional fit because of direct moulding process. Low thermal conductivity Radio density similar to enamel Biocompatible 67. IPS-EMPRESS(PRESSABLE CERAMIC)Hot pressed ceramicsLeucite reinforcedK2O Al2O3 4 SiO2Lithium Disilicate reinforcedSiO2 LiO2 P2O5 ZrO22 typesIPS Empress IPS Empress 2 68. LEUCITE REINFORCED IPS EMPRESSFeldspar Leucite + glass phaseIn congruentMeltingResistance to crack propagationPre cerammed IngotsProcessing : 69. Wax patternCeramic ingot &Al plungerInvestingPressing under vaccum11500CSprue removalEdward B Goldin 2005 compared leucite IPS Empress with PFMMean marginal discrepancy 94 + 41 PFM81 +25 IPSBurn out 8500 C26 min hold 70. Properties :Flexural strength : 117.3 - 167 MpaIon exchange method used to strengthen IPS empress (KnO3)204 Mpa 11 hr immersionEsthetics : high esthetic valueClinical survival : Deniz G in 200295% survival 2-4 yearsMarginal adaptation : Shearer et al in 1996 : better marginal adaptationwith hot pressed ceramics than aluminous core material. 71. LITHIUM DISILICATE REINFORCEDBase glass Melted with raw materials1400 to 16000CPoured into waterGlass grains 20-30 microns Cylindrical ingots obtainedPressed into mold at 9000CinVaccum for 10 minuteAutomatic molding cycle 200to 300 NManufacturing :Mainly for post and core purposes Flexural strength :164+26 MpaCosmo glass Ceramic 72. Full contouring Cut backSprued patternInvesting Ingot pressing 73. CERAPEARLCaO P2O5 MgO SiO2 Hobo and Kyocera bioceram group 1985Crystalline microstructure similar to natural enamelMechanical properties superior to enamelLaboratory steps :Tooth preparation, die preparationWax patterns2 stage burn out (8000C final temperature)Melted ceramic at 14600C casted under vaccum(special ring liners required {1.2mm} )Reheating -870 c Crystalline oxy apatite - moisture exposure hydroxy apatite 74. Clinical success : Nahara Y et al (1991)2 year success rate 100%Burn out chamber Centrifugal casting machineCeramming unit and shadingA) PretreatmentB) 3 months aftercementationC) 2 yrs post-cementationMainly indicated for inlays and full crowns 75. FLUORCANASITEMultiple chain silicate glass ceramic that exhibits high strengthand fracture toughness.Al2O3 CaO F K2O SiO2CaF2 Nucleating agentProcedure :Wax pattern invested in Crystoballite investmentBurn out at 7000C Heat soak for 0.5 hoursTemperature drop to 5900CCentrifugal casting machine used at 12000CDirect ceramming Heat soaking5200CHeating at8600C CANASITE 76. Properties :Flexural strength : 116 12 MPaJohnson et al in 2000 : Biaxial flexural strength 280.4 MpaFracture toughness : 660 Mpa 77. OLYMPUS CASTABLE CERAMICIt consists of glass phase of LiO2 Na2O ZnO Al2O3 TiO2 SiO2 and crystalline phase of Na Mg3 (SiO3AlO10) F2 andLi2OAl2O3 4SiO2Procedure :Burn out 3000C 30 min 8000C for 30 minCasting at 5500C Ceramming at 7500C for 2 hrs.Shimida et al 2000 : prior to cementation : Silane coupling agent +Primerincreases bond strength 78. OPTIMAL PRESSABLE CERAMIC1996 Janeric Pentron CompanyOptimally pressableceramic systemGlass ceramic with leucite phaseCrystalline compacted ceramicon heatingDie fabrication Wax pattern 79. Sprued wax patterns ready forinvestingPaper casting ring is closed from topas the material setsPaper casting ring is peeled Investment placed in burnout furnace850 c -90min 80. Colored pelletsused for castingHot mold placed in optimalauto press machinePressed molds cooledto room temperaturemold is scored and broken apart Recovering of castingRemoval of remaining investment1150 c -20min hold 81. CASTABLE PHOSPHATE GLASS CERAMICContains :Natural phosphate as natural teethMarketed as Crys-Cera 82. MACHINABLECERAMICSLuthy et al 1991Kelly et al 1991Strength > Laboratory fabricated Ceramic 83. CEREC SYSTEMSMaterials involved :Vita mart II, Dicor MGC and Pro CadSanidineKAlSi3O8Micacrystals 70%Leucite containingceramicCERamic REConstruction,Optical scanning 84. The compact, mobile unit consists of three components: asmall camera, a computer screen and a three axis of rotationmilling machine. 85. The cad/cam cerec system has evolved from the: cerec-1,which fabricated only marginally fitting single and dual surfaceceramic inlays.Cerec-2,which showed advances in computing, upgradedsoftware and expanded form of grinding technique. 86. Cerec-3 that can design well-fitting inlays, onlays, crowns,veneers etc., in a single visit. 87. 3D cerecScanning and designing3 dimensional viewing Milling 88. CELAY SYSTEMUses copy milling techniqueResin pattern fabricated directly on master die and pattern is usedfor milling porcelain restorationsJacot et al 1998 : in ceram blanks in celay system.Inlay pattern mounted(copy side)Copy milling pattern outof ceramic material(milling side)Sorenson 1994 : marginal fit of CELAY > CEREC 89. PROCERA SYSTEMDies are enlarged to compensate for sintering shrinkage.ScanningMilling machineShape on computer screenContact scanner 90. Processing methodProcera restorations 91. Tooth color gradation reproducibility : CCM ( computer color matching )Shigemi Ishikawa et al 2005 92. Scope of All-Ceramic 93. Anterior CrownsPosterior Crowns 94. Ceramic insertsInlays & Onlays 95. Porcelain laminate veneersLaminate : Is an extremely thin shell of porcelain applied directly to tooth structure1930-1940 Charles Pincus used thin porcelain shells, denture adhesives were used1970-1980 Composite resin laminate veneers Monochromatic appearanceStainingLoss of luster 96. 1980s Bonding porcelain to etched surfacesHsu et al 1985 - Mechanical retention increased by etching porcelainShear bond strength of etched 4 > UnetchedCalamia et al 1984 - Application of silane coupling agent-Improved bond strength*min thickness of laminate: 0.3 0.5 mm 97. All ceramic F P DTwo part build up Bulk in lingual connector regionPre (PFM)Post (All Ceramic)3 unit FPD 98. DC ZIRKON technique : Vult von steyern et al in 2004< 5% flaws, flexural strength : 900 MpaUsed for posterior FPDsDC-Zirkon Blocks Milled BlockTried on Working Cast 99. All ceramic Resin bonded fixed partial denturesIntroduced 1986-1988 Ibsen et al and Garber et alMatthias kern 2005 :Cantilever resin bonded FPD 100. Ceramic veneer F P DCeramic inlay metal reinforced F P DCeramic veneer / Composite substructure F P D 101. All ceramic Posts1993 Luthy et al Post made of TZP-ZrO2High flexural strength 1400 Mpa1994 Sandhaus Zirconia post with composite core1995 Akagawa et al - Castable ceramic attached to zirconia post1997 Ivoclar introduced Ceramic core directly pressed onto Zirconia postIPS Empress Cosmo ingotDirect methodIndirect method 102. CONCLUSION 103. One who works with his hands is a labourer 104. One who works with his hands & mind is a craftsman 105. One who works with his hands , mind & heart is an artist 106. 1.CONTEMPORARY FIXED PROSTHODONTICS-ROSENSTIEL2.PHILLIPS SCINCE OF DENTAL MATERIALS-ANUSAVICE3.FUNDAMENTALS OF FIXED PROSTHODONTICS-SCHILLINGBURG4.CONTEMPORARY ESTHETIC DENTISTRY:-BRUCE J.CRISPIN5.ESTHETIC DENTISTRY: AN ARTISTS SCIENCE-RATNADEEP PATIL6.JPD 1996;75:18-327.JPD 2004;91:136-438.OPERATIVE DENTISTRY 1990;15:61-709.QUINT INT 1991;22:257-26210.QUINT INT 2005;36:141-147REFERENCES 107. 11.INT J PERIODONT REST DENT 1998;18:587-59312.JOR 2005;32:180-18713.JPD 2002;87:133-13514.DENT MATER 2000;16:226-23315.JPD 2000;83:530-53416.QUINT INT 1985;3:135-14117.JPD 1991;66:754-75818.DENT MATER 2002;18:380-38819.JPD 1991;66:747-75320.J DENT 1990;18:227-235REFERENCES 108. 21.QUINT INT 1998;29:28522.INT J PROSTHOD 1997;10:47823.J PROSTHET DENT 1999;81:27724.QUINT INT 1991;22:257-26225.INT J PROSTHOD 1992;5:9-16REFERENCES 109. Thought for the DayTHERE ARE TWO KINDS OF FAILURESONE WHO THOUGHT AND NEVER DIDONE WHO DID BUT NEVER THOUGHT