METAL FREE CERAMICS- AN UPDATE

RECENT ADVANCES IN DENTAL CERAMICS,MORE OF ABOUT METAL FREE CERAMICS AND ITS APPLICATION

1. METAL FREE CERAMICS- An Update DR. SHAHEEN.V 2 ND MDS, Conservative Dentistry And Endodontics

2. FLOW CHART INTRODUCTION DEFINITIONS HISTORY COMPOSITION OF CERAMICS CLASSIFICATION According To Type According To Firing Temperature According to Substructure material According to the technique of Fabrication.

3. PROPERTIES Esthetics Chemical stability Shrinkage Co efficient of thermal expansion of porcelain Brittleness Dimensional stability Effect of moisture contamination Degradability Abrasion resistance STRENGTHENING OF CERAMICS

4. Conventional powder slurry system Leucite Reinforced feldspahtic porcelain Aluminous based porcelain Alumina reinforced porcelain Magnesia based feldsphatic porcelain Zirconia based Porcelain Hydrothermal low fusing ceramics Slip Cast Ceramics Alumina based (IN-CERAM) IN-Ceram Spinell IN-Ceram Zirconia Injection molded ceramics. Leucite Based Spinel based

5. Machinable ceramics DIGITAL CAD CAM Cerec ANALOGOUS Copy Milling Celay COMPARISON OF DIFFERENT METAL FREE CERAMIC SYSTEMS Fabrication techniques Strength

6. Marginal fit Wear of opposing tooth structure CLINICAL APPLICATION AND SELECTION CRITERIA CEMENTATION OF METAL FREE CERAMICS ADVANTAGES AND DISADVANTAGES REVIEW OF LITERATURE CONCLUSION REFERENCES

7. INTRODUCTION Dental ceramics are materials that are part of systems designed with the purpose of producing dental prostheses that in turn are used to replace missing or damaged dental structures. Metal ceramic restorations have been available for more than three decades. This type of restoration has gained popularity from its predictable performance and reasonable esthetics . Despite its success , the demand for improved esthetics and the concerns regarding the biocompatibility of the metal has lead to the introduction of all-ceramic restorations.

8. Dental ceramic: An inorganic compound with non metallic properties typically consisting of oxygen and one or more metallic or semimetallic elements ( eg . aluminum, calcium, lithium, magnesium, potassium, silicon, sodium, tin, titanium and zirconium) that is formulated to produce the whole or part of a ceramic based dental prosthesis. Anusavice , phillips science of dental materials, 12 th edition, 2012

9. TERMINOLOGIES Feldspathic porcelain A ceramic composed of a glass matrix phase and one or more crystalline phases (such as leucite , K 2 OAl 2 O 3 4SiO 2 ). Glass An inorganic nonmetallic compound that lacks a crystalline structure. Anusavice , phillips science of dental materials, 12 th edition, 2012

10. Glass-ceramic A ceramic consisting of a glass matrix phase and at least one crystal phase that is produced by the controlled crystallization of the glass. Sintering The process of heating closely packed particles to a specified temperature to densify and strengthen a structure as a result of bonding, diffusion, and flow phenomena Glass-infiltrated ceramic A minimally sintered core ceramic with a porous structure that has been densified by the capillary inflow of a molten glass. Anusavice , phillips science of dental materials, 12 th edition, 2012

11. Glass-infiltrated ceramic A minimally sintered core ceramic with a porous structure that has been densified by the capillary inflow of a molten glass. Castable ceramic A glass or other ceramic specially formulated to be cast into a refractory mold to produce a core coping or core framework for a ceramic prosthesis. Core ceramic An opaque dental ceramic material that provides sufficient strength, toughness, and stiffness to support overlying layers of veneering ceramics. Anusavice , phillips science of dental materials, 12 th edition, 2012

12. Pressable ceramic (hot-pressed ceramic) A ceramic that can be heated to a specified temperature and forced under pressure to fill a cavity in a refractory mold . Slip casting A process used to form "green" ceramic shapes by applying a slurry of ceramic particles and water or a special liquid to a porous substrate (such as a die material), thereby allowing capillary action to remove water and densify the mass of deposited particles. Spinel / Spinelle A crystalline mineral composed of mixed oxides such as MgAl 2 O 4 (MgOAI 2 O 3 ). Anusavice , phillips science of dental materials, 12 th edition, 2012

13. Copy-milling The process of cutting or grinding a structure using a device that traces the surface of a master metal, ceramic, or polymer pattern and transfers the traced spatial positions to a cutting station where a blank is cut or ground in a manner similar to a key-cutting procedure. CAD-CAM A ceramic that is formulated for the production of the whole or part of an all-ceramic prosthesis through the use of a computer-aided design and computer-aided manufacturing process. Anusavice , phillips science of dental materials, 12 th edition, 2012

14. HISTORY

15. History of porcelain use in dentistry The use of porcelain in dentistry was first mentioned by Pirre Fauchard . The superior surface and colouring qualities were used by fusing the material to gold or silver. 1728 – Pierre Fauchard , a French dentist first proposed the use of porcelain in dentistry. He suggested the use of jeweler’s enamel to fabricate artificial teeth . 1774 – Alexis Duchateau , a French apothecary with the assistance of a Parisian dentist Nicholas Dubois de Chemant , made the first recorded successful porcelain dentures at the Guerhard Porcelain Factory.

16. 1788 - Nicholas Dubois de Chemant continually improved porcelain formulations and first displayed a baked porcelain denture made in a single block. Published his book on artificial teeth. 1789 – Fused porcelain was introduced for manufacture of teeth . 1806 to1808 – Giuseppangelo Fonzi an Italian dentist who worked in Paris introduced - ‘ terrometallic ’ porcelain tooth . 1837 – John Murphy of London introduced the plantium foil technique 1884 – Dr Charles H.Land pionerred the development of the first glass furnace for fusing porcelain . 1887 – Dr C.H.Land of Detroit developed the first all-porcelain jacket crown (PJC) using the Platinum Foil Matrix techniqe

17. 1889 – Dr.Charles H. Land patented the Plantinum Foil Matrix techniqe for PJC. 1903 – E.B.Spaulding developed gingival shoulder porcelain for the PJC 1962 - M.Weinstein , S. Katz & A. B. Weinstein were awarded the U.S patent for gold alloy formulation and feldspathic porcelain designed for porcelain fused to metal restoration . 1963 to 1965 – The first viable technique for Alumina-reinforced crowns was develoed by McLean &Hughes in England 1976 – McLean & Sced developed the stronger platinum bonded alumina crown. The attachment of aluminous porcelain to the platinum was achieved by surface coating of the metal with a thin layer of tin.

18. 1985 – First CAD/CAM crown was publically milled and installed in the mouth. 1985 – Hobo & Kyocera ( Biocream group ) developed a castable glass-ceramic which melts at 1460 C and flows like molten glass. 1986 – The first generation CEREC 1 (Siemens) CAD/CAM system was introuced . 1988 – Michael Sadoun first introduced In- ceram , a glass- infiltreated aluminous porcelain. 1989 – Duceram LFC, a low fusing Hydrothermal ceramic was introduced 1992 – The Celay copy-milling system ( Mikrona AG), became commercially available.

19. Sintering—Process of heating closely packed particles below their melting temperature to promote atomic diffusion across particle boundaries and densification of the mass. Ceramming is a controlled crystallization of the glass that results in the formation of tiny crystals that are evenly distributed throughout the body of the glass structure.  The size of the crystals, as well at the number and rate of growth is determined by the time and temperature of the ceramming heat treatment. Incongruent melting  occurs when a substance does not melt uniformly and decomposes into another substance. For example, potassium feldspar(KAlSi 3 O 8 ) decomposes to leucite  (KAlSi 2 O 6 ) when it melts. Congruent melting  occurs during  melting of a compound when the composition of the liquid that forms is the same as the composition of the solid

20. 1994 – The second generation CEREC 2 (Siemens/ Sirona ) CAD/CAM System was presented . Late 1990’s – IPS Empress 2, a second generation pressable ceramic made from lithium- disilicate frame work with an apatite layered ceramic was introduced . 1997 – IPS Empress  Cosmo Ingot ( Ivoclar ) , a glass-ceramic material that can be heat pressed directly onto zirconia posts ( eg ; Cosmopost ) was introduced . 1999 – IPS SIGN ( Ivoclar AG), a feldspar-free fluorapatite glass ceramic system for use in metal-ceramics was presented.

21. 2001 - CERCON from Dentsply International introduced dental restorations from unsintered yttrium stabilized zirconia based ceramic core material 2001- Lava™ by 3M™ ESPE ™ 2004- Lava ™ Classic by 3M™ ESPE™ 2006- Lithium disilicate re-emerged in 2006 as a pressable ingot and partially crystalized milling block 2007 - ITERO by Cadent as the first digital impression system for conventionally manufactured crown and bridges. 2008 - E4D Dentist system by D4D technologies, is presently the the only other system besides CEREC that permits same day in- office restoration. 2012 - Lava ™ Plus by 3M™ ESPE ™  is based on a unique 3M™ ESPE™ shading technology 2014 - Lava™ Ultimate is a resin nano ceramic-a new class of CAD/CAM material with unique functionality having an elastic modulus that is comparable to dentin

22. CLASSIFICATION ACCORDING TO TYPE: Feldspathic porcelain Aluminous porcelain Glass infiltrated aluminous Glass infiltrated spinel Glass ceramics ACCORDING TO FIRING TEMPERATURE: High fusing > 1300 c Medium fusing 1101 –1300 C Low fusing 850 – 1101 C Ultra low fusing <850 C. Anusavice , phillips science of dental materials, 12 th edition, 2012

23. According to application For porcelain teeth For Ceramo -metal restorations (Metal-Ceramic Systems), For All-ceramic restorations (All-Ceramic System). R.W . Phillips, 1982, Skinner’s 8Th edition

24. According to the technique of Fabrication 1 . Conventional Powder and slurry ceramics : using condensing sintering Alumina reinforced porcelain : Hi- ceram Magnesia reinforced porcelain : Magnesia cores. Lucite reinforced (high strength) : Optic HSP . Zirconia whisker – fiber reinforced : Mirage II . Low fusing ceramics Hydrothermal LFC : Duceram 2.Castable ceramics - Using casting and Ceramming ( Rosenblum and Alan Schulman. A review of all ceramic restorations JADA March 1997)

25. Fluromicas – Dicor. Apatite based glass – Cera Pearl . Other glass ceramic : Lithia based, CaPO4 based . 3 Machinable ceramics : Milling machining of mechanical digital control. A. Analogous systems (Pantograph system – copying methods) Copy milling / grinding technique Mechanical – Celay Automatic – Ceramatic II DCP . Erosive techniques Sono-erosion : DFS, Erosonic . Spark – erosion : DFS, Procera .

26. B Digital systems (CAD/CAM) Direct- ex : Cerac 1 and cerac 2 Indirect- ex: Ceciro , Denti CAD, Automill , DCS – President 4. Pressable ceramics - By pressure molding and sintering. Shrink free alumina reinforced ceramic (injection molded) Cerestore / Al Ceram. Leucite reinforced ceramic (Heat-transfer molded). IPS express, IPS Impress 2 and OPTEC OPC.

27. 5. Infiltrated ceramics : By slip casting, sintering glass infiltration. Alumina based : In Ceram alumina Spinal based : In Ceram spinal . Zirconia based : In Ceram zirconia.

28. STRUCTURE

29. CRYSTALLINE CERAMICS The only true crystalline ceramic used in restorative dentistry is Alumina (A1 2 O 3 ) which is one of the hardest and probably the strongest oxides known. The hardness and strength of alumina makes it difficult to cleave because of the interlocking nature of the structure. Ceramics are reinforced with crystalline inclusions such as alumina and leucite into the glass matrix to form crystal glass composites as a part of strengthening the material and improving its fracture resistance

30. NON-CRYSTALLINE CERAMICS Ceramic is usually silicate in nature and hence defined as a combination of one or more metals with a non-metallic element, usually oxygen. Ceramic crystals show both ionic and covalent bonds These strong bonds are responsible for Stability, Hardness , High Modulus Of Elasticity , Resistance To Heat & Chemical Attack

31. Feldspathic porcelain Of all the currently available esthetic restorative materials, feldspathic porcelains are closest in matching the translucency and the shade of enamel All the dental porcelains show a reduction in the Kaolin content (to reduce opacity ) and an increase in the feldspar content (to improve their translucency ). Hence dental porcelains can be more appropriately considered as “ Feldspathic glasses with crystalline inclusions of silica ”. Feldspathic Porcelains are glasses based on the Na 2 O-K 2 O- Al 2 O 3 - SiO 2 system. This non-crystalline material is inherently brittle and prone to fracture.

32. INDICATIONS Esthetic alternative to discolored teeth or grossly decayed teeth. Veneers Inlays Onlays Denture teeth material Orthodontics as ceramic brackets CONTRAINDICATIONS Young permanent teeth Small short or thin crowns Porcelain fused to metal is avoided in patients with high lip line. Bruxism

33. ADVANTAGES Biocompatibility Esthetics Durability-wear resistance & solubility High stiffness High melting point Low thermal & electrical conductivity

34. DISADVANTAGES Brittle – low fracture toughness High firing shrinkage of conventional porcelain Attrition of opposing teeth Difficult to repair Technique sensitive Expensive equipments required

35. PROPERTIES OF DENTAL CERAMICS CHEMICAL STABILITY –It is chemically inert. But some form of topical fluoride can damage the porcelain like 1.23 % acidulated phosphate fluoride(APF) or 8% stannous fluoride etches the glass matrix making it dull and rough. SHRINKAGE On heating- linear shrinkage 11.5 % in high fusing porcelain and 14 % in low fusing porcelain. Minimized by using lesser binder , proper condensation, build – up of restoration 1/3 rd larger than original size and firing in successive stages. Operative Dentistry: Modern Theory & Practice by M.A.Marzouk - first edition

36. COLOUR STABILITY Ceramics are the most stable tooth colored materials. The metallic oxides used as colorants do not undergo any change in shade after firing is complete. The smooth glossy surface resists the adherence of exogenous stains. BRITTLENESS Is the relative inability of a material to sustain plastic deformation before fracture of the material occurs. Ceramics are brittle at oral temperatures (5 to 55 C ) Brittle materials such as dental ceramics fail because of the formation and growth of macroscopic flaws that can form during fabrication or in service . Operative Dentistry: Modern Theory & Practice by M.A.Marzouk - first edition

37. CO EFFICIENT OF THERMAL EXPANSION OF PORCELAIN ( 12-13 x 10⁻⁶⁰c) It should be lower than that of the casting alloy to keep the porcelain in residual compression upon cooling from firing temperature. ABRASION RESISTANCE Fused porcelain is the hardest dental material in common use. It will cause metal restorations and tooth structure to wear more rapidly; particularly when not adequately glazed or when glaze is removed during occlusal adjustment (should be smoothened by polishing). Operative Dentistry: Modern Theory & Practice by M.A.Marzouk - first edition

38. Compressive strength of porcelain is good but has a poor tensile strength because of the surface defects like porosities and microscopic cracks. So when place under tension stress concentrates around these imperfections resulting in fracture. Flexure strength Ground 75.8 Mpa Glazed 141.1 Mpa Compressive strength 331 Mpa Tensile strength 34 Mpa Shear strength 110 Mpa Modulus of elasticity 60-70 Mpa Surface hardness 460 KHN ,611-703 VHN Coefficient of thermal expansion Feldspathic 6.4-7.8 x 10⁻⁶/°c Reinforced12.38 – 16.23 x 10⁻⁶/°c Thermal conductivity 2.39 Mcal / s (cm2) °c/cm Specific gravity 2.2- 2.3

39. Strengthening Of Ceramics Ceramics fail at much lower forces because of minute surface scratches and defects on surface Stress concentration on the tips of these scratches , so when there is localized increase in stress concentration it will initiate crack formation . The condensation, melting and sintering process. The high contact angle of ceramics on metal. Differences in the coefficient of thermal expansion between alloy or core and veneers. Tensile stresses during manufacture , function and trauma Anusavice , phillips science of dental materials, 12 th edition, 2012

40. METHOD TO OVERCOME Methods of strengthening brittle materials Designing components to decrease stress concentration Development of residual compressive stresses Interruption of crack propagation Dispersion of crystalline phase Transformation toughening Ion exchange Thermal tempering Thermal compatibility Anusavice , phillips science of dental materials, 12 th edition, 2012

41. Development of residual compressive stress Ion exchange or chemical tempering Exchange of small Na ions with larger K ions (35% larger ) A sodium-containing glass article is placed in a bath of molten potassium nitrate. K+ ions in the bath are exchanged with Na+ ions on the surface of the glass article Anusavice , phillips science of dental materials, 12 th edition, 2012

42. Thermal tempering By rapid cooling (quenching ) the surface of the object while it is hot and in the softened (molten ) core . This rapid cooling produces a skin of rigid glass surrounding a soft (molten) core . For dental application – it is more effective to quench hot glass-phase ceramics in silicone oil or special liquids rather than using air jets that may not uniformly cool the surface Anusavice , phillips science of dental materials, 12 th edition, 2012

43. Thermal compatibility Principle – Slight mismatch between the coefficient of thermal contraction of the core and veneering ceramic material places the outer layer under slight compressive stress rather than tensile stress. Thermal coefficient of contraction of the core ceramic is slightly greater than the thermal coefficient of contraction of the veneering ceramic ( such as opaceous dentin or body /gingival porcelain .

44. Interruption of crack propagation Dispersion of a crystalline phase If a ceramic crystals of high strength and elasticity are dispersed in the glass phase of dental ceramic these harder masses interfere with crack propagation . McLean and Hughes in 1965 , developed a high strength core porcelain using this principle .

45. There should be close match of coefficient of thermal expansion between the crystalline material and the surrounding glass matrix . When a tough crystalline material such as alumina (Al2O3) in particulate form is added to glass, the glass is toughened and strengthened. O’Brien in mid 1980 – used magnesia crystals to reinforce a glass Other crystals which are used are Leucite Lithia disilicate Zirconia Anusavice , phillips science of dental materials, 12 th edition, 2012

46. Transformation toughening Dental ceramics based primarily on zirconia crystals (ZrO 2 ) undergo transformation toughening that involves a transformation from a tetragonal crystal phase to a monoclinic phase at the tip of the cracks that are in the regions of the tensile stress . Anusavice , phillips science of dental materials, 12 th edition, 2012

47. TRANSFORMATION TOUGHENING The transformation of partially stabilized tetragonal zirconia into the stable monoclinic form can also occur under stress and is associated with a slight particle volume increase.

48. CONVENTIONAL POWDER/ SLURRY CERAMICS

49. These products are supplied as powders to which the technician adds water to produce a slurry, which is built up in layers on a die material to form the contours ofthe restoration. The powders are available in various shades and translucencies, and are supplied with characterizing stains and glazes. ( Rosenblum and Alan Schulman. A review of all ceramic restorations JADA March 1997)

50. TYPES :       Alumina – Reinforced porcelain (Aluminous Porcelain ) ·        Hi-Ceram ( vident ), ·        Vitadur – N core ( vident )    Magnesia – Reinforced porcelain (magnesia core ceramics )      Leucite Reinforced (Non-pressed) ·        Optec HSP ( jeneric / pentron ) ·        Optec VP ( jeneric / pentron ) ·        Fortress (Mirage int ) ( Rosenblum and Alan Schulman. A review of all ceramic restorations JADA March 1997)

51.       Low fusing ceramics        Hydrothermal Low- fusing ceramic Eg : Duceram LFC ( Ducera )         Finesse ( Ceramco inc ).   Zirconia reinforced Ceramics Eg .Mirage II (Myron int , Kansas).

52. Alumina based ceramic McLean and Hughes (1965) -Alumina-reinforced porcelain core material for the fabrication of ceramic crowns. Objective Improve aesthetics by a replacement of the thicker metal coping with a thin platinum foil, thus allowing more room for porcelain The first aluminous core porcelains contained 40% to 50% alumina by weight . John W. McLean , September 1967, JADA

53. MASTER MODEL WITH DIE PLATINUM FOIL ADAPTED TO DIE PLATINUM FOIL ADAPTED TO DIE FINISHED CORES

54. DENTIN CERAMIC ADDITIONS UNSINTERED CROWNS FINISHED CROWNS ON DIES POST CEMENTATION

55. Bonding aluminous porcelain to platinum foil copings by use of tin oxide coatings on platinum foil . Bonded foil – Acts as an inner skin on the fit surface -- Reduces subsurface porosity and formation of micro cracks in the porcelain -- Increasing the fracture resistance of crowns and bridges. The clinical performance of these crowns has been excellent for anterior teeth, but approximately 15% of these crowns fractured within 7 years after they were cemented to molar teeth with a glass ionomer cement

56. Disadvantages of Aluminous porcelain Poor esthetics ( Used as a core only). Extensive reduction, dentin preparation. Bonding is limited. Porcelain used for veneering in PFM cant be used with aluminous core porcelain: CTE Alumina core: 8x 10-6/0C Hence requires similar low expansion veneer porcelain. CTE Veneering porcelain for PFM: 13 x 10-6/0C Extensive cracking results upon bonding these materials owing to thermal stresses.

57. Leucite reinforced feldspathic porcelain Optec HSP ( jeneric / Pentron ) Optec HSP is a feldspathic porcelain with 45% volume tetragonal leucite The greater leucite content of optec HSP porcelain compared with conventional feldspathic porcelain for metal ceramic leads to higher modulus of rupture and compressive strength. ( Rosenblum and Alan Schulman. A review of all ceramic restorations JADA March 1997)

58. ADVANTAGES Good transluency compared to alumina crowns Moderate flexural strength (146 Mpa ) higher than conventional feldspathic porcelain DISADVANTAGES Marginal in accuracy caused by marginal porcelain sintering shrinkage Potential to fracture in posterior teeth Increased leucite content may cause relatively higher in vitro wear of opposing teeth USES Employed for Inlays, Onlays , Crowns for low stress areas and Veneers

59. Magnesia based core porcelains Magnesia core porcelains was developed as an experimental material in 1985 (O'Brien, 1985). Magnesia was used as the basis of high expansion core material because co efficient of thermal expansion of magnesia is 13.5 X 10 -6/° c. The core material is made by reacting magnesia with a silica glass within the 1100-1150°C temperature range. This treatment leads to the formation of Forsterite (Mg2Si04) in various amounts, depending on the holding time. The proposed strengthening mechanism is the precipitation of fine forsterite crystals (O'Brien et al, 1993)

60. The difference is explained on the basis that, magnesia has face centered cubic structure , whereas alumina has hexagonal close packed structure . Strengthening is achieved by dispersion strengthening by the magnesia crystals in vitreous matrix and also by crystallization within the matrix .

61. Its high thermal expansion coefficient closely matches that of body and incisal porcelains designed for bonding to metal (13.5 x 10"6/°C). The flexural strength of unglazed magnesia core ceramic is twice as high (131 MPa) as that of conventional feldspathic porcelain (65 MPa). The magnesia core material can be significantly strengthened by glazing, thereby placing the surface under residual compressive stresses that have to be overcome before fracture can occur . (Wagner et al, 1992).

62. ZIRCONIA BASED CERAMICS MIRAGE ƖƖ (MYRON INTERNATIONAL ,KANSAS CITY ) Conventional feldspathic porcelains where tetragonal Zirconia fibres have been . Zirconia undergoes a crystallographic transformation from monoclinic to tetragonal at 1173°C. Partial stabilization can be obtained by using various oxides such as CaO , MgO , Y2O3, and CeO , which allows the high-temperature tetragonal phase to be retained at room temperature

63. MECHANISM OF STRENGTHENING Zirconia undergoes a crystallographic transformation from tetragonal to monoclinic at 1150° C. The translation of partially stabilized tetragonal zirconia into stable monoclinic form can also occur under stress. The result of this transformation is that there is slight particle volume increase resulting in compressive stress that is established on the crack surface , there by inhibiting its growth .

64. HYDROTHERMAL CERAMICS The hydrothermal ceramic systems are basically low fusing porcelains containing hydroxyl groups in the glass matrix. The hydroxyl ion is added to the porcelain structure through exposure to water or water vapours . The hydroxyl addition which Bertschetein and Stepanov termed as “a plasticized layer” supposedly increases chemical resistance ; generates “smoother ” surface profile, and possesses the unique capacity of “healing” surface flaws through the ion exchange process.

65. Hydrothermal ceramics can be formulated as two types : A single phase porcelain Eg : Duceram LFC ® (Degussa Dental, South Plainfield, NJ)      A leucite containing two phase material Eg .: Duceragold ® (Degussa Dental, South Plainfield, NJ)  

66. Self healing effect of hydroxyl surface layer : Conventional porcelains contain surface microflaws or develop them after exposure in the oral environment. These flaw can increase over a time period, resulting in surface dicolourations and reduction in flexural strength. In hydrothermal ceramics an ionic exchange occurs between alkali and hydroxyl groups at the surface layer. This ionic exchange is suggestive of an effect of “healing” surface flaws, thereby contributing to an increase in strength.

67. Duceram LFC : is a low fusing hydrothermal ceramic composed of an amorphous glass containing hydroxyl (-OH) ions. It was developed in mid 1980’s based on the ideas and studies on industrial porcelain ceramic from the early 1960’s and was first introduced to the market in 1989 for use in all ceramic prostheses, ceramic / metal-ceramic inlay and partial crowns.

68. Fabrication of a Duceram ceramic restoration : Two layers of ceramics are to be applied. The base layer - Duceram MC ( Duceram Metal Ceramic ); a Luecite containing porcelain, followed by the veneer - Duceram LFC ( Duceram Low Fusing Ceramic); a low fusing hydrothermal ceramic. Method : Duceram MC is condensed on a refractory die using conventional powder slurry technique and sintered at 930 o C. Over this base layer, Duceram LFC is condensed and sintered at 660 o C. Being highly polishable they do not require glazing.

69. CASTABLE CERAMICS DICOR ( Dentsply Int.) CERA PEARL (Kyocera)

70. Glass ceramic are composite materials of glassy matrix and a crystal phase . A glass -ceramic is material that is formed into the desired shape as a glass, then subjected to a heat treatment to induce partial devitrification ( ie loss of glassy structure by crystallization of the glass). The crystalline particles, needles, or plates formed during this process serve to interrupt the propagation of cracks in the material when an intraoral force is applied, thereby causing increased strength and toughness . The use of glass-ceramics in dentistry was first proposed by MacCulloch in 1968 The first commercially available castable ceramic material for dental use, Dicor , was developed by Corning Glass Works and marketed by Dentsply International . Arvind Shenoy , Journal of Conservative Dentistry | Oct-Dec 2010

71. Dicor system composed of SiO2; K2O. MgO , and MgF2. Small amounts of Al2.O3 and ZrO2 are added for durability and a fluorescing agent is added for esthetics. Dicor contain Tetra silicic fluor mica Crystals Lost wax casting technique is used , similar to that employed for metals. Uses centrifugal casting machine. Glass subjected to heat treatment (1075 degree c for 10 hrs ) that causes microscopic plate like crystals of crystalline material to grow with in the glass matrix Crystallization-65%, crystal is Tetra silicic fluor mica Crystals.

72. This heat treatment (which involves crystal nucleation and crystal growth process) is known as “ ceramming ”. The crystals function in 2 ways: 1) They create a relatively opaque material out of initially transparent crown, 2 ) They significantly increase the fracture resistance and strength of ceramic. These crystals are also less abrasive to opposing tooth structure than the leucite crystals found in traditional feldspathic porcelains

73. Dicor is a glass, it is capable of producing a “ Chameleon Effect ” i.e. part of the colour of the restoration is picked up from the adjacent teeth as well as from the cement used for luting the restoration. The transparent crystals scatter the incoming light and also its color, as if the light is bouncing off a large number of small mirrors that reflect the light and spread it over the entire glass-ceramic Chameleon Effect Frank Spear, JADA, Vol. 139 September 2008

74. WAX PATTERN SPRUCING INVESTING(PO4) BURNOUT

75. Centrifugal casting 1350 C 4mins Divesting 25micron , 40psi Cast glass coping Ceramming

76. CERAMMING CERAMMING OVEN CRYSTALLIZED GLASS COPING

77. Ceramming done from 650-1075°c for 1½ hrs and sustained for 6hrs in order to form tetra silicic flouromica crystals This procedure leads to controlled crystallization by internal nucleation and crystal growth of microscopic plates like mica crystals within the glass matrix.

78. CONVENTIONAL PORCELAIN APPLICATION & FIRING FINISHED CROWN

79. Advantages - Ease of fabrication Improved aesthetics Moderately high flexural strength Low thermal expansion equal to that of tooth structure Minimal abrasiveness to tooth Biocompatibility Less bacterial counts Disadvantages Its limited use in low-stress areas Its inability to be coloured internally.

80. Hydroxyapatite based castable glass ceramics: cerepearl Cerapearl was developed by Sumiya Hobo and Kyocera Bioceram group of Kyoto city ,Japan The main crystalline phase is oxylapatite ,transformable into hydroxyapatite when exposed to moisture . It melts at 1460ºC and flows like a melting glass The cast material has an amorphous microstructure and when reheated at 870ºC forms a crystalline hydroxyapatite . ( Rosenblum and Alan Schulman. A review of all ceramic restorations JADA March 1997)

81. Because of its crystalline constituent similar to natural enamel ,its biocompatible Crystals of enamel have a regular arrangement wheras crystals of cerapearl have an irregular arrangement Hence has a same crystal component as enamel but has a superior mechanical strength.

82. Cerapearl is very white in comparison with natural tooth enamel and requires application of external stain Cerestain by bioceram is designed for this purpose

83. PRESSABLE GLASS CERAMIC Glass-ceramic - A ceramic consisting of a glass matrix phase and at least one crystal phase that is produced by the controlled crystallization of the glass. Are of 2 types Shrink-free Ceramics Leucite -reinforced Glass ceramics Cerestore IPS Empress AI-Ceram Optec Pressable Ceramic (OPC)   Arvind Shenoy , Journal of Conservative Dentistry | Oct-Dec 2010

84. CERESTORE Non-Shrink Alumina Ceramic Is a shrink-free ceramic with crystallized Magnesium Alumina Spinel fabricated by the injection molded technique to form a dispersion strengthened core. Composition Of Shrink Free Ceramic Unfired Composition Fired Composition (Core) A1 2 O 3 (Corundum) 60% MgAl 2 O 4 ( Spinel ) 22% BaMg 2 A1 3 (Barium Osomilite ) 10% Al 2 O 3 (small particles) 43% Al 2 O 3 (large particle) 17% MgO 9% Glass frit 13% Kaolin Clay 4% Silicon resin (Binder) 12% Calcium Stearate 1%

85. On firing a combination of chemical and crystalline transformation produces Magnesium aluminate spinel , which occupies a greater volume than the original mixed oxides (raw ingredients), and thus compensates for the conventional firing shrinkage of ceramic. Chemical transformation: During firing from 160°C to 800°C, the silicone resin (binder) converts from SiO to SiO 2 which in turn combines with alumina to form aluminosilicate . Crystalline transformation: The primary inorganic reaction involves MgO , Al 2 O 3 and the glass frit. The aluminosilicate formed ALUMINA + MAGNESIA  MAGNESIUM ALUMINATE SPINEL (Al 2 O 3 ) ( MgO ) (MgAl 2 O 4 )  

86. Fabrication: By Transfer Molding process which is identical to injection molding of acrylic resin denture bases. Copings are formed by transfer-molding the ceramic directly onto non-shrinking heat stable epoxy master dies The wax pattern on the epoxy die is sprued , invested and burned out. The flask is placed on a heating element (oven) and removed after it reaches the molding temperature. Arvind Shenoy , Journal of Conservative Dentistry | Oct-Dec 2010

87. Shrink-free ceramic material supplied as dense pellets is heated until the silicone resin binder is flowable (160°C) and then transferred by pressure (under a plunger) directly on the master die. The silicone resin binder is thermoplastic and thermosetting, hence after injection into the mold and around the master die, it automatically sets. The flask is quenched and the ceramic coping is fired in a micro-processor controlled furnace (1300°C) to achieve zero-shrinkage. The sintered coping is replaced on the die and veneered with conventional aluminous porcelain.

88. IPS Empress This technique was first described by Wohlwend & Scharer ; and marketed by Ivoclar ( Vivadent Schaan , Liechtensein ). Is a pre- cerammed , pre- coloured leucite reinforced glass-ceramic formed from the leucite system (SiO 2 -AI 2 O 3 -K 2 0) by controlled surface crystallization, subsequent process stages and heat treatment The partially pre- cerammed product of leucite -reinforced ceramic powder available in different shades is pressed into ingots and sintered. The ingots are heated in the pressing furnace until molten and then injected into the investment mold. Frank Spear, JADA, Vol. 139 September 2008

89. Following the burn out procedure, the ring along with the investment is placed In a specialized mould that has an alumina plunger The ceramic ingot is placed under the plunger . The entire assembly is heated to 1150°C and the plunger presses the molten ceramic into the mould

90. The cylinder is then pressed under vacuum into the mould and held under pressure to allow complete and accurate fill of the investment cavity The crown is formed in dentin shades Enamel layering is added in Empress furnace for necessary translucency and staining .

91. Ips empress ii FRANK et al 1998 ,EDELHOFF et al 1999, POSPEICH et al 1999 Indicated in all ceramic bridges ,anterior and posterior crowns It is similar except that the core contains Lithia disilicate crystals in a glass matrix and veneering ceramics contains apatite crystals The lithium disilicate has an unusual microstructure in that it contains very small inter locking crystals that are very randomly oriented

92. This is ideal from point of view of strength because the needle like crystals cause cracks to deflect, blanch or blunt thus propagation of cracks through this material is arrested by lithium disilicate crystals ,providing substantial increase in flexural strength. A second crystalline phase containing of a lithium ortho phosphate ( li3po4) of a much lower volume is also present The high strength creates the possibility of not only creating anterior and posterior crowns but also posterior bridges .

93. In Empress I the leucite core ceramic is identical to the veneering ceramic so a mismatch in co efficient of thermal expansion does not arise. However for Empress II co efficient of thermal expansion is greater ,hence a compatible layering ceramic had to be developed. This new layering is an apatite glass ceramic The apatite crystals influence the translucency ,brittleness and light scattering ability of layering ceramics. The material has improved density and handling characteristics Frank Spear, JADA, Vol. 139 September 2008

94. Empress esthetic Lee cup et al A newer leucite reinforced glass ceramic with a broader ingot shade range ,greater homogeniety ,greater density ,greater flexural strength When used with traditional staining techniques it provides better esthetics When coupled with IPS Empress Esthetic veneering materials and Empress esthetic wash pastes, provides life like translucency of the restoration .

95. Features Broader ingot shade range Greater homogeneity Greater density Greater flexural strength Chameleon effect Natural translucency and fluorescence Excellent press results

96. IPS e . Max The new all ceramic system (lithium disilicate ) from ivoclar vivadent ,which is marketed under the brand name IPS e .max for the press and CAD CAM technology.

97. COMPOSITION quartz, lithium dioxide, phosphor oxide, alumina, potassium oxide other components 70% needle like crystals embedded in glass matrix approximately 3-6 µm in length.

98. PROPERTIES of lithium disilicate (LS 2 ) Highly aesthetic Highly thermal shock resistant glass ceramic due to the low thermal expansion . High strength material that can be cemented or bonded . Offers a unique solution with its ability to offer a full contour restoration fabricated from one high-strength ceramic, thereby eliminating the challenge of managing 2 dissimilar materials.

99. GLASS INFILTRATED CERAMICS

100. Slip Cast Ceramics(glass Infiltrated Ceramics) INCERAM FAMILY Inceram alumina Inceram spinel Inceram zirconia Inceram sprint Frank Spear, JADA, Vol. 139 September 2008

101. Developed by a French scientist and dentist Dr. Michael Sadoun (1980) A Slip is a suspension of fine insoluble particles in a liquid The In-Ceram Crown ( Vident ) process involves three basic steps : Making an intensely dense core by slip casting of fine grained alumina particles and sintering. The sintered alumina core is infiltrated with molten glass to yield a ceramic coping of high density and strength. The infiltrated core is veneered with feldspathic porcelain and fired

102. In ceram Alumina Slip casting : A special ultrasonic device (In-Ceram Vitasonic II), Liquid (water), fine grained (1-5um) alumina powder and an additive are combined and stirred under ultrasonic agitation to give a homogenous mass The slip is painted on a special plaster model made of porous refractory matrix (In-Ceram Special Plaster) needed to compensate for the sintering shrinkage of the slip.

103. As the liquid from the slip cast is absorbed into the die by capillary action, additional layers are added (0.5 to 0.7mm thick). Framework is shaped roughly before the first firing. The alumina layer is allowed to dry (30 mins ), Sintering (10 hour firing cycle of upto 1120 C) in a special furnace (In- Ceramat ) to produce an organized microstructure. The coping is fragile and porous in nature.

104. Glass - infiltration A specially formulated low-fusing glass-infiltrate (lanthanum glass) powder is mixed with distilled water. The frameworks are set on a platinum-gold foil and the glass-water slurry is applied over the external surface of the porous substructure. The infiltration firing is performed for 4 to 6 hours at 1100 C (in the In- Ceramat furnace).The glass infiltrate melts at 800°C Frank Spear, JADA, Vol. 139 September 2008

105. At 1100°C the molten glass diffuses through the interstitial spaces of the porous alumina core by capillary action and encapsulates the fine grain alumina particles. This infiltration firing increases the strength of the core to about 20 times its original strength. The plaster (gypsum die) shrinks during sintering so the glass-infiltrated coping can be easily removed from the die Frank Spear, JADA, Vol. 139 September 2008

106. DUPLICATION IN-CERAM REFRACTORY DIES IN-CERAM APPLICATION WORKING MODEL

107. AL 2 O 3 SLIP {10 HRS 1120 C- 2HRS} VITA INCERAMAT SHRINKAGE OF DIES GLASS INFILTRATION 4HRS 1100 C

108. APPLICATION OF BODY AND INCISAL PORCELAIN POSTOPERATIVE VEIW OF IN-CERAM CROWNS FINISHED IN-CERAM COPINGS FINISHED CROWNS PREOPERATIVE VEIW

109. PROPERTIES STRENGTH : The densely packed crystalline particles (70% alumina ) Limit crack propagation and prevent fracture . Studies have shown that though the compressive strength of In-Ceram lies between that of IPS Empress Pressable glass-ceramic and metal-ceramic restorations, its fracture resistance did not differ significantly from the metal-ceramic restorations . ( Giordono et al,1995)

110. COLOR : The final color of the In-Ceram restorations is generally influenced by the color of the alumina core, which tends to be opaque. In spinell variety, the core is more transparent   USES: Single anterior & posterior crowns Anterior 3-unit FPD's

111. ADVANTAGES Optimum aesthetics and excellent biocompatibility. Withstands high functional stress due to excellent physical values No thermal irritations on account of low thermal conductivity Offers the possibility of non-adhesive seating Radiolucent High degree of acceptance among the patients

112. INDICATIONS- Single crowns 3 unit anterior bridges Contraindications:- Insufficient hard tooth substance available Inadequate preparation results Bruxism

113. In ceram spinell Magnesium spinell (MgAl 2 O 4 ) as the major crystalline phase with traces of alpha-alumina, which improves the translucency of the final restoration. Final core material – Glass infiltrated magnesium spinell Advantages Spinell has extended uses(Inlay / Onlay, ceramic core material and even Veneers.) Disadvantage 25% reduction in strength Incapable of being etched by hydrofluoric acid.

114. In ceram zirconia Contains tetragonal zirconia and alumina as the major crystalline phase . Final core material – 30%wt Zirconia + 70%wt Alumina Advantage High flexural strength ( 1.4 times the stability as the ln-Ceram Alumina) Excellent Marginal Accuracy Biocompatibility . Disadvantage : Poor esthetics due to increased opacity.

115. 350 MPa 500 MPa 700 MPa In- ceram Alumina In- ceram Spinell In- ceram Zirconia Flexural strength

116. In ceram sprint ʺ The time saving system ʺ Vita In ceram sprint provides rapid production of alumina crown copings . The furnace firing time has been dramatically reduced compared with conventional firing methods

117. MACHINABLE CERAMICS

118. MACHINING SYSTEM CAD-CAM(DIGITAL) COPYING SYSTEMS (ANALOGOUS) DIRECT Cerec 1 Cerec 2 INDIRECT Automill Denti CAD COPY MILLING EROSION 1.MANUAL 1.SONOEROSION Celay DFE Erosonic 2.AUTOMATIC 2.SPARK EROSION Ceramatic DFE Procera

119. CAD-CAM Ceramics 　In dentistry, the major developments of dental CAD/CAM systems occurred in the 1980s. There were three pioneers in particular who contributed to the development of the current dental CAD/ CAMsystems . Dr. Duret contributed in the field of dental CAD/CAM development . Dr. Moermann , the developer of the CEREC® system3 . Dr. Andersson , the developer of the Procera . Dental material journal 2009,28,44-45

120. Uses digital information about the tooth preparation or a pattern of the restoration to provide a computer-aided design (CAD) on the video monitor for inspection and modification. The image is the reference for designing a restoration on the video monitor. Once the 3-D image for the restoration design is accepted, the computer translates the image into a set of instructions to guide a milling tool (computer-assisted manufacturing [CAM]) in cutting the restoration from a block of material.

121. Advantages Negligible porosity levels in the CAD-CAM core ceramics. Freedom from making an impression. Reduced assistant time associated with impression procedures Need for only a single patient appointment (with the Cerec system), and good patient acceptance. Disadvantages Need for costly equipment. The lack of computer-controlled processing support for occlusal adjustment The technique sensitive nature of surface imaging required for the prepared teeth . Dental material journal 2009,28,44-45

122. BASIC WORKING PRINCIPLE OF CAD CAM SYSTEM COMPUTER AIDED DESIGN & COMPUTER AIDED MANUFACTURING

123. CAD/ CAM Systems exhibit three computer linked functional components  1.    Computerized surface digitization  2.    Computer - aided design  3.    Computer - assisted manufacturing Gary Davidowitz The Use of CAD/CAM in Dentistry ,Dental Clinics, Vol. 55, Issue 3, p559–570

124. STEP 1 - OBTAINING AN OPTICAL IMPRESSION Data from the patient i.e. tooth and soft tissue, or master cast or impression is captured electronically with the aid of - INTRAORAL SPECIALIZED CAMERA OR LASER SYSTEM OR MINIATURE CONTACT DIGITIZER OR SAPPHIRE PROBE Gary Davidowitz The Use of CAD/CAM in Dentistry ,Dental Clinics, Vol. 55, Issue 3, p559–570

125. STEP 2 – RESTORATION DESIGN Data thus acquired is now analyzed using CAD software provides a 3 – Dimensional image of future restoration A 3 – Dimensional image of future restoration is produced which is analyzed in all planes to avoid any variations with original structure. Using the CAD software an Occlussal Analysis is made, any undercuts are marked and digital image is sent to clinician for correction

126. STEP 3 - RESTORATION PRODUCTION Restoration is then produced by Machining with computer controlled milling machines Electric discharge machining

127. THE CEREC SYSTEM CEREC concept was given in 1980 by W. Moermann and M. Brandestini and developed by Siemens. The term was selected for the CAD/ CAM machine from the words “ CEramic REC onstruction ” CEREC I was restricted to Inlays, Onlays and Veneers CEREC - I Dental CAD/CAM systems: A 20-year success story. E. Dianne Rekow . J Am Dent Assoc 2006;137;5S-6S

128. STEP I – POWDER APPLICATION Optical Characteristics of Enamel and Dentin prevent cavity preparations from being three dimensionally scanned. A layer of CEREC powder is applied to make the tooth surface opaque and non – reflective. Powder is inert and removed with a simple air – water spray A green powder( TiO 2 )wet can spray was introduced to produce even deposition of powder.

129. STEP II – OBTAINING THE OPTICAL IMPRESSION A small hand held video camera with a 1 cm wide lens is placed close to the occlusal surface Thus, image is digitized and the vertical dimension ( depth of cavity ) is measured by shift in incident and reflected light i.e. deeper parts show more shift

130. STEP III – ANALYSIS OF IMAGE A “ reverse mouse ” is used and the cursor is first placed on gingival margin against buccal wall and moved along all internal line angles.

131. Two main types of ceramic are used Conventional Porcelain containing quartz in a feldspathic porcelain block  VITA and CERAMCO Porcelain without Quartz  DICOR Porcelain block is mounted on a metal stub which is then loaded on milling unit. Entire milling operation takes 4 – 6 minutes. Milling is done by means of a diamond covered disk in conjunction with high velocity air – water spray. STEP IV – MILLING OF THE CERAMIC RESTORATION

132. DIAMOND COATED MILLING DISC MILLING IN PROGRESS – Synchronous movement of grinding wheel and bur

133. The image further shows the percentage of milling process that is completed A continuous read out also comes showing the efficiency of diamond wheel and probable need for replacement Stages representing Milling of the Restoration from The block

134. ADVANTAGES Natural Esthetics Optimal Cutting and Quality of Material ensure an accurate restoration Glazing is not required Minimal abrasion of hard tissues as restorations are fabricated meeting occlusal demands High stability during various occlusal excursive movements 6 High patient acceptance as restoration can be provided to patient chair side 7. Cost of Porcelain used is equal to Composite resin as minimal material is used. 8. Conventional Impression steps and preparation of models avoided thus laboratory processing time is reduced.

135. DISADVANTAGES Complicated Software Limited Color identification range Costly investment Very bulky and requires expertise to master the functioning.

136. Clinical shortcoming of Cerec 1 system :    Although the CEREC system generated all internal and external aspects of the restoration, the occlusal anatomy had to be developed by the clinician using a flame-shaped, fine-particle diamond instrument and conventional porcelain polishing procedures were required to finalize the restoration.    Inaccuracy of fit or large interfacial gaps.    Clinical fracture related to insufficient depth of preparation. Relatively poor esthetics due to the uniform colour and lack of characterization in the materials used.

137. Developed by Moermann and Brandestini I ntroduced in September 1994 , and is the result of constant further development via different generations of Cerec units to eliminate the previous limitations .   The major changes include :    Enlargement of the grinding unit from 3 axis to 6 axis.   Upgrading of the software with more sophisticated Cerec 2 system

138.   Data representation in the image memory and processing increased by 8 times Magnification factor increased from x8 to x12 for improved accuracy during measurements.  Monitor can be swiveled and tilted, thus facilitating visual control of the video image. Other technical innovations of Cerec 2 compared to Cerec 1 :   The improved Cerec 2 camera : new design, easy to handle, a detachable cover (asepsis), reduction in the pixel   

139. CEREC 3D CEREC 3D is an acronym for Chairside Economical Restoration of Esthetic Ceramics Introduced in January, 2000 and after one year of Clinical use and studies it was introduced in 2001 Cerec 3D uses CAD/CAM (Computer Aided Design/Computer Aided Manufacturing) Technology, incorporating a camera, computer and milling machine in one instrument. The dentist uses a special camera to take an accurate picture of the damaged tooth.

140. This optical impression is transferred and displayed on a color computer screen, where the dentist uses CAD technology to design the restoration . Then CAM takes over and automatically creates the restoration while the patient waits. Finally, the dentist bonds the new restoration to the surface of the old tooth. The whole process takes about one hour.

141. Computer monitor Function switches Base containing pump unit and water supply Storage drawers Optical impression Tracker ball Milling unit

142. Dr. Stefan Eidenbenz , University of Zurich, developed this 8 axis milling machine called CELAY in 1990. It has two main features: A Hand Operated contacting probe that traces the external contours of an acrylic or wax inlay, fabricated in mouth. A milling arm, follows the probe by means of a pantographic arm, with 8 degrees of freedom, thus cuts the copy of a “Pro Inlay (wax or acrylic pattern)” from a porcelain block. CELAY employs no computer; a direct copy milled restoration is obtained. THE CELAY SYSTEM

143. There are four main steps in this procedure: Fabrication of a PRO – INLAY Copy Milling Insertion Finishing.

144. The CELAY Copy Milling Machine with Schematic representation Of 8 axes of geometric transfer mechanism

145. The Scanning device Scanning a wax pattern The Milling device cuts a porcelain block WAX Pattern for Crown Coarse diamond points used for initial processing of porcelain

146. FINISHING OF PORCELAIN COPING WITH 64 MICRONS DIAMOND POINT FINISHED CROWNS

147. Cercon The Cercon Zirconia system ( Dentsply Ceramco , Burlington, NJ) consists of the following procedures for production of zirconia -based prostheses.

148. PROCERA ALL CERAM SYSTEM (Nobel Biocare ) PROCERA system was introduced in 1986. Initially it was used to fabricate crowns and FPDs by combining a Titanium substructure with a low fusing veneering porcelain. Later in 1993 it was used to produce All ceramic crowns. The crown is composed of a densely sintered, high purity aluminium oxide coping that is combined with a low fusing veneering porcelain.

149. PROCEDURE Procera ® Piccolo enables single tooth scanning for crowns, laminates and abutments. Procera ® Forte scan crowns, laminates and abutments as well as bridges.

150. Sapphire ball forms the tip of the scanner. Extremely light pressure of approx 20g maintains the probe in contact with the die

151. Within 3 mins , more than 50,000 data points are gathered , defining the three dimensional shape of the die .

152. Next step in designing is to establish the thickness of the coping to be fabricated. Relief space for the luting agent is automatically established by computer algorithm . Sintering shrinkage of 20% is taken into account , so enlarge model of the preparation is made with the help of the CAD-CAM technique . High purity aluminum oxide powder is compacted against the enlarged die The outer surface is milled and the coping is sintered to full density . Then veneering porcelain is added

153. Lava all ceramic system Consists of a non contact optical scan system , a pc with monitor and the LAVA CAD Windows based software which displays the model as three dimensional object. LAVA Milling unit This computer controlled precision milling unit can mill out 21 copings or bridge frameworks without supervision or manual intervention LAVA therm Bridges and crown frameworks undergo sintering and exact dimensions ,density and final strength in the high temperature LAVA therm furnace

154. Lava ™ Plus Based on a unique 3M™ ESPE™ shading technology This unique technology used in the lava™ premium dyeing liquids also helps to preserve translucency after shading, without compromising strength. Lava™ Ultimate A resin nano ceramic-a new class of CAD/CAM material with unique functionality having an elastic modulus that is comparable to dentin

155. Features of the YTZP blanks : They are pre sintered The shade of the core material can also be stained resulting in the ability to control the shading of the restoration. The core is translucent in comparison with other zirconia based ceramic core systems . Other systems Sopha ( designed by DURET ) DentiCAD (BEGO ,Germany and DentiCAD ,USA)

156. DCS-PRESIDENT Introduced in 1990 by DCS production Switzerland DC Zirkon blocks (Y-TZP) blocks from which crown and core copings are milled are fully sintered However it is said that the white colored, opaque core material may limit the esthetic quality of the restoration . Procedure A conventional wax model is digitized with preciscan laser scanner The precimill machining center mills the substructure from from fully sintered DC Zircon Blank .

157. Hybrid ceramics HAHN proposed a new ceramic which is hybrid between organic and inorganic components Organic and inorganic components Polyvinyl siloxane 50 vol % Titanium active filler 1 μ m 30 % Inert filler ( aluminium oxide ) 15% Titanium boride 5 % The mixture is handled like composite and cured They can be veneered with feldspathic porcelains

158. Lumineers No preparation Indicated for slightly stained ,discolored , chipped , maligned tooth without removal of tooth structure Bonded to enamel

159. • Lumineers can be placed on the teeth without removal of the tooth structure. • Patients can receive their veneers quickly, usually within two weeks from the date that the impressions are made. • Lumineers bond directly to the tooth , making the bond very strong . They are also very long-lasting - up to twenty years or longer. • Lumineers are a reversible procedure . Advantages

160. PREPARATION OF LUMINEERS Clean the teeth with Porcelain Laminate Polishing Paste and rinse . Perform minimal enamelplasty with a prep diamond bur, using light pressure. –Use the whole length of the bur, keeping contact with the teeth. 1. Polishing 2. Refresh the Enamel

161. Isolate the teeth receiving 1. Etch the teeth with Etch ‘N’ Seal® for 20 seconds. 2. Rinse thoroughly with water, then dry. 3. Interdental Strips 4. Etching

162. 6. Prime-Bonding on LUMINEE RS 1. Add 1 coat of Tenure A+B on the inner side of the LUMINEERS. 2. Add 1 coat of Tenure S on the inner side of the LUMINEERS. 7. Ultra-Bond ® Plus on LUMINEE RS Add an even layer of Ultra-Bond ® Plusresin cement to the inner side of the LUMINEERS . Work upwards from incisal edge of the LUMINEERS to gingival edge and keep light contact with the LUMINEERS

163. 8. Insert the LUMITray 1. Remove the Paint-On Dental Dam or interdental strips. 2. Center the LUMITray (midline). 3. Insert the tray in one smooth movement. Apply light and continuous buccal pressure. Take your time for the placement. 4. Remove excess Ultra-Bond Plus resin cement from the gingiva with a microbrush .

164. 9. Cure LUMINEE RS Through LUMITray 1. Tack-cure each tooth using a sweeping movement.Set Light for 3 seconds. 2. Remove more excess cement with a probe. 3. Light-cure each tooth for 3 seconds through the tray.

165. 10. Clean-Up and Open Interdental Spaces 1. Remove Ultra-Bond Plus cement from interproximal spaces.Maintain complete control over the instrument. If difficult, postpone to follow-up visit. 2. Remove excess cement using the finishing bur kit.

166. 11. Light-Cure the LUMINEE RS Light-cure each LUMINEERS individually for a second time, on both the lingual and buccal sides, for 5 seconds with Sapphire Light . 12. Check Occlusion and Polish 1. Check and finish the occlusion. 2. Polish the LUMINEERS with Porcelain Laminate Polishing Paste.

167. CERAMIC INSERTS Eg : Cirona   Pressed leucite inlay  Etched with HF and silanised , with a shelf-life of over five years, before being sealed into a sterile blister pack Indications Class I, II (conventional and tunnel design), III, and IV cavities Closure of endodontic access cavities B J Millar Primary Dental Care: Journal of the Faculty of General Dental Practitioners (UK) 1999, 6 (2): 59-62

168. Size-matched  cerana  burs  The cavity is refined using one of three conical burs  Size- and shaped-matched conical inlay is cemented using a conventional restorative resin material The final restoration consists of a leucite inlay surrounded by a small amount of composite resin. The exposed resin, has a higher filler loading than that of a luting cement B J Millar Primary Dental Care: Journal of the Faculty of General Dental Practitioners (UK) 1999, 6 (2): 59-62

169. Restoration of a Class II cavity

170. DOUBLE INLAY Hannig and schmeise Proximal boxes extending into dentine are restored with a conventionally cemented metal base and then covered with a porcelain inlay having margins confined to enamel Indications Proximal cavities in deeply damaged molars and premolars with margins extending into the root dentin Advantages Cast restoration at the critical cervico proximal cavity margins The esthetic and stabilizing properties of the adhesively bonded restoration technique in visible areas Dailey B 1 The double-inlay technique: a new concept and improvement in design, J Prosthet Dent.2001 Jun;85(6):624-7

171. Natural inlays  'Recycling' of extracted teeth for the production of dental restorations. Using the celay milling machine Two pairs of matching sound extracted permanent molar teeth were used The molars were matched for mesio -distal size of the tooth crown and the convexity of the proximal surfaces One tooth of each pair was assigned to be the 'donor' tooth, the other tooth being the 'host‘.  Mo inlay preparations were made in the host teeth Moscovich H,   Creugers NH The novel use of extracted teeth as a dental restorative material, J Dent.1998 Jan;26(1):21-4 .

172. Spark Erosion It refers to 'Electrical Discharge Machining' ( EDM. It may be defined as a metal removal process using a series of sparks to erode material from a work piece in a liquid medium under carefully controlled conditions. The liquid medium usually, is a light oil called the ‘dielectric fluid’. It functions as an insulator, a conductor and a coolant and flushes away the particles of metal generated by the sparks.