all ceramic materials- Dr Rasleen Sabharwal


Published on

Published in: Business, Technology
No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

all ceramic materials- Dr Rasleen Sabharwal

  1. 1. GOOD MORNING • .
  2. 2. ALL CERAMIC MATERIALS Presented By : Dr Rasleen Kaur Sabharwal Dept Of Prosthodontics Sri Rajiv Gandhi Dental College And Hospital
  3. 3. CONTENTS Introduction History of ceramics Composition of ceramics Properties of ceramics Classification of dental ceramics Methods of strengthening ceramics Conventional powder slurry ceramics 
  4. 4. . Castable ceramics Machinable ceramics Pressable ceramics Infiltrated ceramics Zirconia based systems Conclusion References
  5. 5. INTRODUCTION Dental ceramic is one of the most biological and esthetically acceptable material in dentistry. Ceramics are used for manufacturing artificial teeth, pontics, facing, crowns and fixed bridges. Dental porcelain in this domain is superior over polymers and reinforced polymers regarding toothshade reproduction, translucency, biological compatibility, chemical stability and abrasion resistance.
  6. 6. Ceramic is derived from GREEK word “KERAMI KOS” meaning Burnt earth Ceramics : compounds of one or more metals with a non metallic element(usually silicon, boron, oxygen) that may be used as a single structural component or as one of the several layers that are used in the fabrication of a ceramic based prosthesis . (G.P.T 8, Anusavice)
  7. 7.  Porcelain : a ceramic material formed of infusible elements joined by lower fusing materials. Most dental porcelains are glasses and are used in fabrication of teeth for dentures, pontics & facings, crowns, inlays, onlays and other restorations. (G.P.T 8)
  9. 9. The first porcelain tooth material was patented in 1789 by a French dentist deChemant in collaboration with a French pharmacist Duchateau. The first commercial porcelain was developed by Vita Zahnfabrik in about 1963 JPD 1996 JAN 18-32; CERAMICS IN DENTISTRY : HISTORICAL ROOTS AND CURRENT PERSPECTIVE
  10. 10. 1887 PJC – CH. Land (platinum foil technique) 1940 with advent of acrylics PJC lost popularity 1957 Vines and Sommelman – Vaccum firing 1962 PFM – Weinstein 1965 McLean and Hughes aluminium core porcelain
  11. 11. 1968 – castable ceramics (Mc Culloch) 1970 – hydrothermal ceramics 1980 – Duceram LFC 1980 – Cerec system (Brain.A.g, Switzerland) 1984 – Magnesia reinforced porcelain
  12. 12. 1988 – Inceram 1994 - Cerec 2 system (Morman & Brandestini) 2006 – Cerec 3 (Akbar, Walker, Williams)
  13. 13. Composition of a dental porcelain (feldspathic) Material Silica Alumina Boric oxide Potash Soda Other oxides weight% 63 17 7 7 4 2 F e ld s p a r D e n ta l P o r c e la in D o m e s tic P o r c e la in S to n e w a re K a o lin E a rth e n w a re Q u a rtz
  14. 14. The various ingredients used in different formulations of ceramics are : 1.Silica (Quartz or Flint) – Filler 2.Kaolin (China clay) – Binder 3.Feldspar – Basic glass former 4.Water – Important glass modifier 5.Fluxes – Glass modifiers 6.Colour pigments
  15. 15. 7.Opacifying agents 8.Stains and colour modifiers 9.Fluorescent agents 10.Glazes and Add-on porcelain 11.Alumina 12.Alternative porcelain additives to
  16. 16. Silica  Pure Quartz crystals (SiO2) are used for manufacturing dental porcelain. Quartz (crystalline silica) is used in porcelain as a filler and strengthening agent.
  17. 17. Kaolin ( White China Clay) Its functions are: It increases the moldability of the plastic porcelain Acts as a binder and helps in maintaining the shape of the unfired porcelain during firing. At high temperature, it fuses and reacts with other ingredients to form the glassy matrix.
  18. 18. Feldspars Types of feldspar : Ø Soda feldspar – Decreases fusion temperature Ø Potash feldspar – Increases the viscosity of glass.
  19. 19. Role of feldspar Ø Glass phase formation: During firing, the feldspar fuses and forms a glassy phase that softens and flows slightly allowing the porcelain powder particles to coalesce together. The glassy phase forms a translucent glassy matrix. Ø Leucite formation: Another important property of feldspar is its tendency to form the crystalline mineral leucite.
  20. 20. Leucite Is a potassium-aluminum-silicate mineral with a high coefficient of thermal expansion ( 20-25x10o/ oC) compared to feldspathic glasses ( 10x10o/oC). It is an artificial crystal feldspathoid ( K2O.Al2O3.4siO2) formed by the incongruent melting (Incongruent melting is the process by which one material melts to form a liquid plus a different crystalline material) of feldspar ( K2O.Al2O3. Al2O3-4SiO2). Annu Rev Mater Sci 1997 27:443-68 ceramics in restorative and prosthetic dentistry : J Robert Kelly
  21. 21. Functions of Leucite To raise the coefficient of thermal expansion of porcelain and bring it closer to that of the metal substrate; consequently increasing the hardness and fusion temperature.
  22. 22. Glass formers Glass is basically composed of silica (SiO2) with oxides of Sodium, Potassium, Calcium, Barium etc. The principal anion in all glasses is O2 ion, which forms very stable bonds with small multivalent cations such as Silicon, Boron, Germanium or Phosphorus resulting in formation of random networks of SiO4 tetrahedral in glass. These ions are thus termed as Glass Formers.  
  23. 23. Glass Modifiers Can be defined as elements that interfere with the integrity of the SiO2 (glass) network and alter their three-dimensional state. Their functions are: Ø     to decrease the softening point by reducing the amount of cross linking between oxygen and glass forming elements. Ø   decrease the viscosity (flux action increasing the flow)
  24. 24. Intermediate Oxides Addition of glass modifiers to reduce the softening point also decreases the viscosity, resulting in slump or pyroplastic flow; hence it is necessary to produce glasses with high viscosity as well as low firing temperature. This can be done by the incorporation of an intermediate oxide such as alumina (Al2O3), to increase the viscosity of glass.
  25. 25. Boric Oxide fluxes Boric Oxide (B2 O3) although a powerful flux (glass modifier), it can also act as a glass former and form its own glass network, producing Boron Glasses.
  26. 26. Water Although not an intentional addition, water is an important glass modifier.
  27. 27. Colouring agents Dental porcelains colored by the addition of concentrated colour frits which are prepared by fritting high-temperature resistant colouring pigments (generally metallic oxides) into the basic glass.
  28. 28. The color pigments used are: Ø  Pink - Chromium or chrome-aluminia Ø  Yellow-indium (lemon) – Titanium Ø  Blue -Cobalt salts in the form of oxide Ø  Green - Chromium oxide Ø  Grey -Iron oxide (black) or platinum oxide
  29. 29. Ø Other pigments used may be Titanium oxide –yellow brown, manganese oxide- lavender, iron/nickel oxide-brown, and copper oxide – green.
  30. 30. Opacifying agents The translucency of porcelain is not suitable to produce dentin colours in particular, which requires greater opacity than that of enamel colors. An opacifying agent maybe incorporated, which generally consists of a metal oxide. The common metallic oxides used are – Ø      Cerium oxide Ø      Titanium oxide
  31. 31. Ø      Tin oxide and Ø   Zirconium oxide (ZrO2)- most popularly used opacifying agent (usually added with the concentrated color frit to the porcelain during final preparation).
  32. 32. Stains & Colour Modifiers The stains and colour modifiers supplied with dental porcelain are prepared in much the same way as colour frits.
  33. 33. Properties of porcelain: Strength: Porcelain has got good strength, but is brittle and tends to fracture. Strength is usually measured in terms of flexural strength Flexural stength: – Ground porcelain - 75.8 Mpa. – Glazed porcelain - 141.1Mpa. Compressive strength – 331 Mpa. Tensile strength – 34 Mpa .Low because of surface defects like porosities & microscopic cracks Shear strength - 110Mpa.
  34. 34. Specific Gravity: True Specific Gravity is 2.242. Fired porcelains sp gravity is less due to presence of air voids Dimensional stability: Dimensionally stable Chemical stability: Insoluble and impermeable to oral fluids. Resistant to most solvents. HF acid is used to etch porcelain to improve bonding of the resin cement
  35. 35. Esthetic properties: Able to match adjacent tooth structures in translucency, colour & intensity. Colour stability – excellent ,retain its colour & gloss for years. Biocompatibility: Excellent compatibility with oral tissues.
  37. 37. Dental porcelains are classified according to the firing temperatures as: High fusing 1300°C (237°2F) Medium fusing 1101 – 1300°C (2013 –2072° F) Low fusing 850 – 1100°C (1962 – 2012°F) Ultra-low fusing <850°C (1562°F)
  38. 38. Structure Ceramics can apper as either crystalline or amorphous solids (also called glasses); Thus, ceramics can be broadly classified as : Ceramics Non-Crystalline Ceramics Eg-feldspathic porcelain Crystalline Ceramics aluminous porcelain
  39. 39. ACC TO DENT CLIN N AM  Predominantly glassy materials eg feldspathic porcelain Particle filled glasses eg dicor  Polycrystalline ceramics eg procera Dent Clin N Am 48 (2004) 513-530 Dental ceramics: current thinking and trends( J Robert Kelly)
  40. 40. ALL CERAMIC SYSTEMS( JADA, VOL. 128, March 1997) 1) Conventional Powder – Slurry Ceramics : using condensing & sintering. (a) Alumina reinforced Porcelain e.g. : Hi-Ceram (b) Magnesia reinforced Porcelain e.g.: Magnesia cores (c) Leucite reinforced (High strength porcelain) e.g. : Optec HSP (d) Zirconia whisker – fibre reinforced e.g.:MirageII (Myron Int) (e) Low fusing ceramics (LFC): (i) Hydrothermal LFC e.g.: Duceram LFC (ii)Finesse(Ceramco Inc)
  41. 41. 2) Castable Ceramics : Using casting & ceramming (a) Flouromicas e.g: Dicor (b) Apatite based Glass-Ceramics e.g Cera pearl (c) Other Glass-Ceramics e.g: Lithia based, calcium phosphate based.
  42. 42. 3) Machinable Ceramics : Milling machining by mechanical digital control A)Analogous Systems (Pantograph systems – copying methods) 1) Copy milling / grinding techniques a) Mechanical e.g. : Celay b) Automatic e.g:Ceramatic II. DCP 2)  Erosive techniques : a) Sono-erosion e.g: DFE, Erosonic b) Spark-erosion e.g: DFE, Procera
  43. 43. B) Digital systems (CAD / CAM): 1)Direct e.g: Cerec 1 & Cerec 2 2) Indirect e.g : Cicero, Denti CAD, Automill, DCS-President
  44. 44. 5) Infiltrated Ceramics by slip-casting, sintering & glass infiltration 1) Alumina based 2) Spinel based 3) Zirconia based e.g: In-Ceram Alumina e.g: In-Ceram Spinel e.g.: In-Ceram Zirconia
  45. 45. MANUFACTURING ACC TO JED Platinum foil technique Refractory die technique Casting system technique Heat pressing technique Slip casting technique Hand operated copy milling Sonoerosion system CAD CAM Journal of esthetic dentistry : all ceramic restorations: a challenge for anterior esthetics : Nicola Pietrobon
  46. 46. The advantages of All-ceramic restorations include: Ø     Increased translucency Ø      Improved fluorescence Ø     Greater contribution of colour from the underlying tooth structure Ø      Inertness Ø      Bio-compatibility Ø      Resistance to corrosion Ø      Low temperature / electrical conductivity
  47. 47. Characteristic Features of All-Ceramic Crowns Ø  Excellent esthetic result. Ø  Moderate strength for single - unit anterior tooth restorations when bonded with resin cement. Ø  Lack of gray/ brown metal show through since a metal substructure is absent.
  48. 48. Ø  Inability to cover the color of a darkened tooth preparation or post core, since the crowns are translucent. Ø  Laboratory costs higher than those for typical PFM crowns.
  49. 49. Ø      Wear of opposing occluding enamel or dentin if the pressed all-ceramic crowns are a part of heavy incisal guidance or canine rise. Ø      Difficulty in removing the crown and cementing medium when replacement is necessary (Bonded pressed ceramic crowns are much more difficult to remove than standard PFM crowns)
  50. 50. Methods of strengthening ceramics Strengthening of ceramics by – i) Introduction of residual compressive stresses into the surface of material by a) Ion exchange (chemical tempering) b) Thermal tempering c) Thermal compatibility (mismatch of CTE) Annu Rev Mater Sci 1997. 27:443-68 Ceramics in restorative and prosthetic dentistry : J Robert Kelly
  51. 51. ii) Disruption of crack propagation – a) Dispersion of a crystalline phase eg . Alumina – b) Tranformation toughening by Zirconia crystals (ZrO2)
  52. 52. Methods of strengthening brittle materials Interruption of crack propagation Residual compressive stresses 1.Ion exchange 2.Thermal tempering 3.Thermal compatiability Addition of dispersion phase Toughness of particle Change in crystalline structure Al, dicor Particle stabilized zirconia Minimise stress concentration 1. Reducing stress raisers 2. Minimise tensile stresses
  53. 53. Ion exchange/ chemical tempering Increase in the flexural strength of feldspathic dental porcelain up to 80% is seen depending on the ionic species involved and the composition of the porcelain.
  54. 54. Thermal tempering creates residual surface compressive stresses by rapidly cooling (quenching) the surface of the object while it is hot and in the softened(molten)state. quench hot glass-phase ceramics in silicone oil or other special liquids This thermal tempering treatment induces a protective region of compressive stress within the surface.
  55. 55. Thermal compatibility mismatch The metal and ceramic should be selected with a slight mismatch in their thermal contraction coefficients so that the metal contracts slightly more than the ceramic on cooling from the firing temperature to room temperature . This mismatch leaves the ceramic in residual compression and provides additional strength for the prosthesis.
  56. 56. Dispersion of crystalline phase Dispersion strengthening/ crystalline reinforcement Reinforcing ceramic with a dispersed phase of a different material that is capable of hindering a crack from propagating through the material Dental ceramics can be strengthened by increasing the crystal content of leucite, lithia disilicate, alumina ,magnesia-alumina spinel,and zirconia
  57. 57. Transformation toughening When small tough crystals are homogenously distributed in the glass, the ceramic structure is strengthened because cracks cannot penetrate the fine particles as easily as they can penetrate the glass. Various dispersed crystalline phases includes alumina,leucite,tetrasilicic fluormica, lithia disilicate, and magnesia alumina spinel.
  58. 58. When pure zirconia is heated between 1470-2010 oC & is cooled at room temperature its crystals begin to change from tetragonal to monoclinic phase at about 1150 oC. Additives like 3 mol% yttrium oxide can prevent this polymorhic transformation In zirconia based ceramics, tranformation toughening involves a tranformation of ZrO2 from a tetragonal crystal phase to a monoclinic phase at the tips of cracks that are in regions of tensile stress. Dent Clin N Am 48(2004) 513-530 Dental ceramics : current thinking and trends
  59. 59. Transformation toughening
  60. 60. Glazing The principle is the formation of a low-expansion surface layer formed at high temperature. Upon cooling, the lowexpansion glaze places the surface of the ceramic in compression and reduces the depth and width of surface flaws. With contemporary dental ceramics, self-glazing is the standard technique
  62. 62. TYPES : Alumina – Reinforced porcelain (Aluminous Porcelain Magnesia – Reinforced porcelain (magnesia core ceramics) Leucite Reinforced Low fusing ceramics Zirconia whisker - fibre reinforced
  63. 63. ALUMINA – REINFORCED PORCELAIN (ALUMINOUS PORCELAINS ) Alumina glass composites used in dental ceramic work have been termed “Aluminous Porcelain” (McLean & Hughes, 1965).
  64. 64. Porcelains used in an all aluminous porcelain crown consists of :       Aluminous core porcelain : which contains 40-50 % by wt fused alumina crystals fritted in a low- fusing glass. The alumina (α - alumina ) particles dispersed in the glass matrix have very high tensile strength. They are stronger and more effective in interrupting crack propagation; thus strengthening the crystal - glass composite material progressively by two to three folds.      
  65. 65. Incorporation of alumina produces dull/ opaque porcelain with lack of translucency. Hence used as a core material (0.5 -1mm) over plantinum foil veneered with feldspathic porcelain. Alhough improved in strength, it is still insufficient to bear high stresses. Eg:Vitadur – N(Vident) Hi – Ceram (Vident)
  66. 66. Disadvantages Ø      Low coefficient of thermal expansion in the range of 8*10-6/0C. Ø      Requires specially formulated and compatible enamel and dentin porcelains for veneering. Improvement in strength is insufficient to bear high stresses.
  67. 67. Fracture resistance in the aluminous PJC was improved by a technique, in which the platinum matrix was left in the completed restoration . The plantium foil matrix not only provided additional support to the porcelain ; it also allowed a chemical bond between the tin-plated foil but it did decrease the amount of light trasnmitted, which diminished somewhat the esthetic advantages of an all-ceramic restoration.
  68. 68. Master model with dies Platinum foil adapted to die Finished Cores
  69. 69. MAGNESIA – REINFORCED PORCELAIN   Magnesia Core Ceramics are high expansion ceramics described by O’Brien in 1984 for use as core material . The magnesia crystals strengthen the glass matrix by both dispersion strengthening and crystallization within the matrix .
  70. 70. The flexural strength of the material is 131 Mpa but may be doubled (upto 269 Mpa) by the application of a glaze internally. In addition, glass infiltration also significantly increases the fracture strength of magnesia core.
  71. 71. Advantages: Increased coefficient of thermal expansion (CTE 14.5x106/0C) improves its compatibility with conventional feldspathic veneering porcelains . (CTE: 12 to 15x 10-6/0C). Improved strength and a high expansion property compared to conventional feldspathic porcelain makes it suitable for use as a core material , thus substituting for a metallic core as substructure.
  72. 72. LEUCITE – REINFORCED PORCELAINS Leucite-Reinforced Glass Ceramics are feldspathic porcelains, dispersion strengthened by crystallization of leucite crystals in the glass matrix .
  73. 73. Optec HSP (Optec (Jeneric/Pentron) high is a Strength leucite porcelain) reinforced feldspathic porcelain that is condensed and sintered like aluminous and traditional feldspathic porcelain on a refractory die instead of a platinum foil . Despite the increase in crystallization ,the material retains its translucency apparently because of the closeness of the refractive index of leucite with that of the glass matrix . The flexure strength is approximately 140 Mpa.
  74. 74. Composition : It is a glass ceramic with a leucite content of 50.6 weight % dispersed in a glassy matrix uses : Inlays , onlays, crowns and veneers.
  75. 75. Advantages Ø Despite lack of metal or opaque substructure, it has high strength by leucite reinforcement, hence can be used as a core material. Ø  Good translucency Ø  Moderate flexural strength Ø  No special laboratory equipment needed.
  76. 76. Disadvantages Ø Potential marginal inaccuracy caused by porcelain sintering shrinkage. Ø  Potential to fracture in posterior regions. Increased leucite content may contribute to high abrasive effect on opposing teeth.
  77. 77. LOW FUSING CERAMICS Hydrothermal ceramics are a new cateogory of dental ceramics developed from industrial ceramics by introducing hydroxyl groups into the ceramic structure under heat and steam from which the term ‘hyrdothermal’ ceramic is derived.
  78. 78. The hydrothermal ceramic systems are basically low fusing porcelains containing hydroxyl groups in the glass matrix . Although the melting, softening and sintering temperatures had reduced, these materials exhibited an increase in thermal expansion and mechanical strength without a compromise in their chemical solubility.
  79. 79. Advantage of hydrothermal ceramics over conventional porcelains: Ø  Lower fusion temperature (680-700 C) Ø  Increased coefficient of thermal expansion Ø  Minimal abrasion of opposing dentition Ø  Greater toughness and durability
  80. 80. 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.
  81. 81. Advantages over feldspathic porcelain:   Greater density   Higher flexural strength   Greater fracture resistance   Lower abrasion than feldspathic porcelain  Surface resistant to chemical attack by fluoride containing agents  Highly polishable, not requiring re-glazing during adjustment.
  82. 82. Disadvantages : low coefficient of thermal expansion. Thus, an inner lining of conventional high-fusing ceramic is required.
  83. 83. FINESSE ALL CERAMIC SYSTEM The finesse all ceramic ingots are designed to be used only with the finesse low fusing porcelain to fabricate highly esthetic, all ceramic single unit restoration, laminate veneers, inlays and onlays.
  84. 84. Indications:  Single unit anterior and posterior premolar restorations  Laminate veneers  Inlays  Onlays  The finesse all ceramic ingots are color coordinated and thermally matched only to the finesse low fusing porcelains.
  85. 85. Contra-Indications: High fusing and other low fusing porcelains are not thermally matched and will not have the correct coefficient of thermal expansion and therefore should not be used. While initial results with some materials may appear acceptable internal stress can compromise long term success.
  87. 87. Glass-ceramics that are polycrystalline materials developed for application by casting procedures using the lost wax technique, hence referred to as “castable ceramic”.
  88. 88. Castable dental Glass-Ceramics   Fluoromicas OtherGlass-Ceramics (SiO2K2MgOA12O3ZrO2) Based on a) Lithia E.g Dicor b) calcium phosphate Apatite Glass-Ceramic (CaOMgOP2O5SiO2 system E.g: Cera Pearl (Kyocera Bioceram)
  89. 89. Dicor: Dicor, the first commercially available castable glass-ceramic material for dental use was developed by The Corning Glass Works (Corning N.Y.) and marketed by Dentsply International (Yord, PA, U.S.A). The term “DICOR” is a combination of the manufacturer’s names: Dentsply International & Corning glass.
  90. 90. Dicor is a castable polycrystalline fluorine containing tetrasilicic mica glass-ceramic material, initially cast as a glass by a lost-wax technique and subsequently heat treated resulting in a controlled crystallization to produce a glass - ceramic material.
  91. 91. Major Ingredients SiO2 45-70%, K2O upto 20%; MgO 13-30%   MgF2 (nucleating agent & flux 4 to 9%) Minor Ingredients A12O3 upto 2% (durability & hardness) ZrO2 upto 7%; Fluorescing agents (esthetics) BaO 1 to 4% (radiopacity)
  92. 92. Advantages of Dicor Ø Chemical and physical uniformity Ø Excellent marginal adaptation (fit) Ø Compatibility with lost-wax casting process Ø Uncomplicated fabrication from wax-up to casting, ceramming and colouring Ø Ease of adjustment
  93. 93. Ø  Excellent esthetics resulting from natural translucency, light absorption, light refraction and natural colour for the restoration. Ø  Relatively high strength (reported flexural strength of 152 MPa), surface hardness (abrasion resistance) and occlusal wear similar to enamel. Ø  Inherent resistance to bacterial plaque and biocompatible with surrounding tissues. Ø  Low thermal conductivity.
  94. 94. Disadvantages Ø Requires special and expensive equipments such as Dicor casting machine, ceramming oven. Ø Failure rates as high as 8% (# of the restoration) were reported, especially in the posterior region. In addition, failure rates as high as 35% have been reported with full coverage Dicor crowns not bonded to tooth.
  95. 95. Wax pattern Centrifugal casting 26000 f Spruing Divesting Investing Cast glass coping Burnout Ceramming
  96. 96. Ceramming Ceramming oven Crystallised glass coping Cerramming done from room temparature- 19000 f for 1½ hrs and sustained for 6hrs inorder to form tetra silicic flouro mica crystals Conventional porcelain application & Firing Finished crown
  97. 97. CASTABLE APATITE GLASS CERAMIC   Castable apatite ceramic is classified as CaO-P2O5-MgO-SiO glass ceramic.   1985 -Sumiya Hobo & Iwata developed a castable apatite glass-ceramic which was commercially available as Cera Pearl (Kyocera Bioceram, Japan).
  98. 98. CERA PEARL (Kyocera San Diego, CA): contains a glass powder distributed in a vitreous or non-crystalline state. Composition: Approximately (By weight) Ø Calcium oxide -45% Ø Phosphorus Pentoxide -15% glass formation Ø Magnesium oxide -5% Decreases viscosity Ø Silicon dioxide -35% glass matrix Ø Other -Trace elements Nucleating agents
  99. 99. Desirable characteristics of Apatite Ceramics Ø      Cerapearl is similar to natural enamel in composition, density, refractive index, thermal conductivity, coefficient of thermal expansion and hardness. Similarity in hardness prevents wear of opposing enamel.
  100. 100. Lithia Based Glass-Ceramic   Developed by Uryu; and commercially available as -Olympus Castable Ceramic (OCC)   Composition: It contains mica crystals of NaMg3 (Si3AlO10) F2 and Beta Spodumene crystals of LiO.AI2O3.4SiO2 after heat treatment.
  101. 101. Calcium Phosphate Glass-Ceramic  Reported by Kihara and others, for fabrication of allceramic crowns by the lost wax technique. It is a combination of calcium phosphate and phosphorus pentoxide plus trace elements. The glass ceramic is cast at 1050°C in gypsum investment mold. The clear cast crown is converted to a crystalline ceramic by heat treating at 645°C for 12 hours. Reported Flexural strength (116 Mpa); Hardness close to tooth structure.
  102. 102. Disadvantages Weaker than other castable ceramics. Opacity reduces the indication for use in anterior teeth.
  103. 103. Advantages of castable glass ceramics Ø High strength Ø Excellent esthetics resulting from light transmission Ø Accurate form for occlusion, proximal contacts, and marginal adaptation. Ø Uniformity and purity of the material. Ø Favorable soft tissue response. Ø X-ray density allowing examination by radiograph
  104. 104.  Hardness and wear properties closely matched to those of natural enamel     Similar thermal conductivity and thermal expansion to natural enamel  Dimensional stability regardless of any porcelain corrective procedure and subsequent firings
  106. 106. Triad of fabrication: Fabrication of a restoration whether with traditional lost-wax casting technique or a highly sophisticatedtechnology such as a CAD/CAM system has three functional components:      Data acquisition      Restoration design      Restoration fabrication  
  107. 107. Machinable Ceramic system (MCS) for dental restorations: Ø      Digital Systems (CAD/CAM): Direct Indirect   Three steps : §         3-dimensional surface scanning §         CAD -Modelling of the restoration §         Fabrication of restoration.
  108. 108. Ø      Analogous systems (Copying methods) Copy Milling / Copy Grinding or Pantography Systems Two steps : §   Fabrication of prototype for scanning. §   Copying and reproducing by milling
  109. 109. DIGITAL SYSTEMS Computer aided design and computer aided manufacturing (CAD/ CAM) technologies have been integrated into systems to automate the fabrication of the equivalent of cast restorations. 
  110. 110. CAD/CAM milling 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.
  111. 111. CEREC SYSTEM (direct CAD CAM) The CEREC (Ceramic Reconstruction) system ( Siemen/sirna corp) Cerec System consists of : Ø  A 3-D video camera (scan head) Ø  An electronic image processor (video processor) with memory unit (contour memory) Ø  A digital processor connected to, Ø  A miniature milling machine (3-axis machine)
  112. 112. Machinable ceramics ( Ceramics used in machining systems) are pre-fired blocks of feldspathic or glass ceramics.   Composition : Modified feldspathic porcelain or special fluoro-alumino-silicate compositions are used for machining restorations.
  113. 113. Properties Ø      Excellent fracture and wear resistance Ø      Pore-free Ø      Possess both crystalline and non-crystalline phase (a 2-phase composition permits differential etching of the internal surface for bonding).
  114. 114. Ceramic CAD/ CAM restorations are bonded to tooth structure by : Ø Etching for a bond to enamel(with HF) Ø Conditioning, priming and bonding (when appropriate) Ø Cementing with luting resin.  
  115. 115. Two classes of machinable ceramics available are:       Fine-scale feldspathic porcelain Glass-ceramics
  116. 116.  Cerec Vitabloc Mark I : This feldspathic porcelain was the first composition used with the Cerec system (Siemens) with a large particle size (10 - 50µm). It is similar in composition, strength, and wear properties to feldspathic porcelain used for metal-ceramic restorations. Cerec Vitabloc Mark II : This is also a feldspathic porcelain reinforced with aluminum oxide (20-30%) for increased strength and has a finer grain size (4µm) than the Mark I composition to reduce abrasive wear of opposing tooth JADA VOL 137 : sept 2006: Clinical performance of chairside CAD/CAM restorations: Dennis J Fasbinder
  117. 117. CEREC SYSTEMS CERamic REConstruction Materials involved : Vita mark II Sanidine KAlSi3O8 Dicor MGC Mica crystals 70% Pro Cad Leucite containing ceramic Optical scanning
  118. 118. The compact, mobile unit consists of three components: a small camera, a computer screen and a three – axis – of – rotation milling machine.
  119. 119. The cad/cam cerec system has evolved from the cerec-1,which fabricated only marginally fitting single and dual surface ceramic inlays.
  120. 120. Cerec-2,which showed advances in computing, upgraded software and expanded form of grinding technique.
  121. 121. Cerec-3 that can design well-fitting inlays, onlays, crowns, veneers etc., in a single visit.
  122. 122. 3D cerec Scanning and designing 3 dimensional viewing Milling
  123. 123. Dicor MGC (Dentsply, L.D. Caulk Division) : This is a machinable glass-ceramic composed of fluorosilica mica crystals in a glass matrix. The micaplates are smaller (average diameter 2 um) than in conventional Dicor (available as Dicor MGC - light and Dicor MGC dark). Greater flexural strength than castable Dicor and the Cerec compositions. Softer than conventional feldspathic porcelain. Less abrasive to opposing tooth than Cerec Mark I, and more than Cerec Mark II (invitro study results).
  124. 124. Other machinable ceramics being developed include: Ø      Bioglass (Alldent Corp., Rugell, Liechtenstein) Ø      DFE -Keramik/Krupp Medizintechnir GmbH, Essen, Germany; Bioverit / Mikrodenta Corp Ø      Empress / Vivadent –lvoclar Corp, Schaan, Liectenstein.
  125. 125. The clinical advantages of the Cerec system: Ø The restorations made from prefabricated and optimized, quality-controlled ceramic porcelain can be placed in one visit. Ø    Transluency and color of porcelain very closely approximate the natural hard dental tissues. Ø    Further, the quality of the ceramic porcelain is not changed by the variations that may occur during processing in dental laboratories. Ø    The prefabricated ceramic is wear resistant.
  126. 126. COMET System (Coordinate M Easuri ng Technique, Steinbichler Optotechnik, GmbH, Neubeurn, Germany) This system allows the generation of a 3-dimensional data record for each superstructure with or without the use of a wax-pattern. For imaging, 2 - dimensional line grids are projected onto an object, which allows mathematical reproduction of the tooth surfaces.
  127. 127. It uses a pattern digitization and surface feedback technique, which accelerates and simplifies the 3-dimensional representation of tooth shapes while allowing, individual customization and correction in the visualized monitor image.
  128. 128. Advantage of CAD/CAM (Cerec system)over other systems Ø Eliminates impression model making and fabrication of temporary prosthesis. Ø Dentist controls the manufacturing of the restoration entirely without laboratory assistance. Ø Single visit restoration and good patient acceptance. Ø Alternative materials can be used, since milling is not limited to castable materials. Ø The use of CAD/ CAM system has helped provide void free porcelain restorations, without firing shrinkage and with better adaptation.
  129. 129. Ø      CAD - CAM device can fabricate a ceramic restoration such as inlay/ onlay at the chair-side. Ø      Eliminates the asepsis link between the patient, the dentist, operational field and ceramist. The shapes created in the CAD unit are well defined, and thus a factor such as correct dimensions can be evaluated and corrections/modifications can be carried out on the display screen itself .
  130. 130. Glazing is not required and Cerec inlay onlays can easily be polished.  Minimal abrasion of opposing tooth structure because of homogeneity of the material (abrasion does not exceed that of conventional and hybrid posterior composite resins).  The mobile character of the entire system enables easy transport from one dental laboratory to another.
  131. 131. Disadvantages: Ø  Limitations in the fabrication of multiple units. Ø  Inability to characterize shades and translucency. Ø  Inability to image in a wet environment (incapable of obtaining an accurate image in the presence of excessive saliva, water or blood). Ø  Incompatibility with other imaging system. Ø  Extremely expensive and limited availability. Ø  Still in early introductory stage with few long-term studies on the durability of the restorations.
  132. 132.  Lack of computer-controlled processing support for occlusal adjustment.  Technique sensitive nature of surface imaging that is required for the prepared teeth.  Time and cost must be invested for mastering the technique and the fabrication of several restorations, to develop proficiency in the operator.
  133. 133. PROCERA System : The Procera System (Nobel Biocare, Gioteborg, Sweden) embraces the concept of CAD/CAM to fabricate dental restorations. It consists of a computer controlled design station in the dental laboratory that is joined through a modern communication link to Procera Sandvik AB in Stockholm, Sweden, where the coping is manufactured with advanced CAD/CAM technique.
  134. 134. Procedure requires 3 steps for fabrication:      Scanning : At the design station, a computer controlled optical scanning device maps the surface of the master die and is sent via modem to the Procera production facility. Machining : At the production facility, an enlarged die is fabricated that compensates for the 15-20% sintering shrinkage of the alumina core material. High-purity alumina powder is pressed onto the die under very high pressure, milled to required shape, and fired at a high temperature (1550°C) to form a Procera coping.
  135. 135. veneering : The sintered alumina coping is returned to the dental laboratory for veneering with thermally compatible low fusing porcelains (All Ceram veneering porcelain) to create the appropriate anatomic form and esthetic qualities. All Ceram veneering porcelain (Ducera) has a coefficient of thermal expansion adjusted to match that of aluminium oxide (7x106 /°C).
  136. 136. Advantages  It has the fluorescent properties similar to that of natural teeth and the veneering procedures require no special considerations.  The reported flexural strength of the Procera All Ceram crown (687 Mpa) is relatively the highest amongst all the all-ceramic restorations used in dentistry (attributed to the 99.9% alumina content).
  137. 137. PROCERA SYSTEM Dies are enlarged to compensate for sintering shrinkage. Scanning Contact scanner Shape on computer screen Milling machine
  138. 138. Processing method
  139. 139. This system can be used to fabricate two types of dental restorations :       A Porcelain-fused-to-metal restoration made of titanium substructure with a compatible veneering porcelain using a combination of machine duplication and spark-erosion (The Procera Method, Noble Biocare). An all-ceramic restoration using a densely sintered high-purity (99.9%) alumina coping combined with a compatible veneering porcelain.
  141. 141. PRESSABLE CERAMICS Shrink-free Ceramics Leucite-reinforced Glass-ceramics Cerestore IPSEmpress Ceram AlOptec Pressable Ceramic(OPC)
  142. 142. SHRINK FREE ALUMINA CERAMICS The shortcomings of the traditional ceramic material and techniques; like failures related to poor functional strength and firing shrinkage limited the use of "all-ceramic" jacket crowns. The development of non-shrinking ceramics such as the Cerestore was directed towards providing an alternate treatment Shrink-free ceramics were marketed as two generation of materials under the commercial names : •    Cerestore (Johnson & Johnson. NJ, USA) • Al-Ceram (Innotek Dental Corp, USA)
  143. 143. CERESTORE Non-Shrink Alumina Ceramic (Coors Biomedical Co., Lakewood, Colo.) 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 Fired Composition (Core) A12O3 (Corundum) 60% MgA12O4 (Spinel) 22% BaMg2A13(Barium Osomilite) 10%
  144. 144. Unfired Composition  A12O3 (small particles) 43% A12O3 (large particle) 17% MgO 9% Glass frit 13% Kaolin Clay 4% Silicon resin (Binder) 12% Calcium Stearate 1% Sterylamide 1%
  145. 145. Advantages : Ø      Innovative feature is the dimensional stability of the core material in the molded (unfired) and fired states. Hence, failures related to firing shrinkage are eliminated. Ø      Better accuracy of fit and marginal integrity. Ø      Esthetics enhanced due to depth of colour due to the lack of metal coping. Ø      Biocompatible (inert) and resistant to plaque formation (glazed surface).
  146. 146. Ø      Radiodensity similar to that of enamel (presence of Barium osomilite phase in the fired core allows radiographic examination of marginal adaptation). Ø      Low thermal conductivity; thus reduced thermal sensitivity. Low coefficient of thermal expansion and high modulus of elasticity results in protection of cement seal.
  147. 147. Disadvantages : Ø  Complexity of the fabrication process. Ø  Need for specialized laboratory equipment (Transfer molding process) and high cost. Ø  Inadequate flexural strength (89MPa) compared to the metal-ceramic restorations. Ø  Poor abrasion resistance, hence not recommended in patients with heavy bruxism or inadequate clearance.
  148. 148. Limitations and high clinical failure rates of the Cerestore led to the withdrawal of this product from the market. The material underwent further improvement and developed into a product with a 70 to 90% higher flexural strength. This was marketed under the commercial name Al Ceram (Innotek Dental, Lakewood, Colo.).
  149. 149. LEUCITE REINFORCED PORCELAINS ( Transfer-molded ) Leucite reinforced porcelains can be broadly divided into two groups: Ø  Pressed – ·  IPS Empress & IPS Empress 2 (Ivoclar) · Optec Pressable Ceramic / OPC (Jeneric/Pentron) Ø  Non-Pressed ·   Optec HSP & Optec VP (Jeneric / Pentron) ·   Fortress (Mirage)  
  150. 150. Pressed Ceramic / Injection Molded Glass Ceramic are leucite-reinforced, vacuum-pressed glass-ceramic, also referred to as Heat transfer-molded glass ceramics. Eg: IPS Empress (Ivoclar Williams); Optec (Jeneric Pentron) IPS EMPRESS (Ivoclar Williams) is a pre-cerammed, pre-coloured leucite reinforced glass-ceramic formed from the leucite system (SiO2-AI2O3-K20) by controlled surface crystallization and heat treatment.
  151. 151. The glass contains latent nucleating agents and controlled crystallization is used to produce leucite crystals measuring a few microns in the glass matrix. 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.
  152. 152. Uses : Ø      Laminate veneers and full crowns for anterior teeth Ø      Inlays, Onlays and partial coverage crowns Ø      Complete crowns on posterior teeth. JED: vol 9 no 3: Indirect ceramic system for posterior teeth: Luca L Dalloca, Roberto Brambilla
  153. 153. Advantages : Ø  Lack of metal or an opaque ceramic core Ø  Moderate flexural strength (120-180MPa range) Ø  Excellent fit (low-shrinkage ceramic) Ø  Improved esthetics (translucent, fluorescence) Ø  Etchable Ø  Less susceptible to fatigue and stress failure Ø  Less abrasive to opposing tooth Ø  Biocompatible material
  154. 154. Disadvantages : Ø  Potential to fracture in posterior areas. Ø Need for special laboratory equipment such as pressing oven and die material (expensive) Ø Inability to cover the colour of a darkened tooth preparation or post and core, since the crowns are relatively translucent. Ø Difficulty in removing the crown and cementing medium during replacement. Compressive strength and flexural strength lesser than metal-ceramic or glass-infiltrated (In-Ceram) crowns.
  155. 155. OPTEC (Optimal Pressable Ceramic/OPC): Optec stands for Optimal Technology. It is a type of feldspathic porcelain with increased Ieucite content designed to press restorations using leucite-reinforced ceramic in a press furnace that doubles as a conventional porcelain furnace.
  156. 156. However, because of its high leucite content, it can be expected that its abrasion against natural teeth will be higher than that of conventional feldspathic porcelain. Fabrication is similar to IPS Empress
  157. 157. Uses :       Full contour restorations (inlays, veneers full crowns) Alternately used as a core material, veneered with conventional feldspathic porcelain (similar to Optec HSP).
  158. 158. IPS EMPRESS 2 (Ivoclar) -Second generation of pressable materials for all-ceramic bridges. It is made from a lithium disilicate framework with an apatite layered ceramic. The glass-ceramic ingots are made from lithium silicate glass crystals with crystal content of more than 60 volume%. The apatite crystals incorporated are responsible for the improved optical properties (translucency, light scattering) which contribute to the unique chameleon effect of leucite glass-ceramic materials.
  159. 159. IPS Empress 2 is used with special investment material, an EP500 press furnace and a fully automatic high-tech furnace. Other applications : Cosmopost and IPS Empress cosmoingot - core build-up system with the pre-fabricated zircon oxide root canal posts and the optimally coordinated ingot.
  160. 160. Wax pattern Ceramic ingot & Al plunger Investing Pressing under vaccum 11500C 26 min hold Burn out 8500 C Sprue removal Edward B Goldin 2005 compared leucite IPS Empress with PFM Mean marginal discrepancy 94 + 41 PFM 81 +25 IPS
  161. 161. INFILTRATED CERAMICS compendium/ march 1998 vol 19 no 3 Edward A McLaren
  162. 162. IN-CERAM ALUMINA, IN-SPINELL, AND IN-CERAM ZIRCONIA Slip casting technique: A slurry of one of these materials is slip-cast on a porous refractory die and heated in a furnace at 1200c for 2 hr to produce a partially sintered coping. The partially sintered core is infiltrated with a glass at 1100 0c for 4 hr to eliminate porosity and to strengthen the slip –cast core.
  163. 163. Flex st In-ceram Alumina 350 MPa In-ceram Spinell 500 MPa In-ceram Zirconia 700 MPa The final ICA core consists of 70 wt% alumina infiltrated with 30 wt% sodium lanthanum glass. ICS core- Glass infiltrated magnesium spinel (Mgal2O4). ICZ Core- 30 wt% zirconia and 70 wt% alumina
  164. 164. • The flexural strength of in-ceram is greater than that of Dicor, OPC, IPS Empress I and Empress II. • ICS is the most translucent of the three ceramics. • ICZ is not recommended for anterior prostheses because of its high level of opacity.
  165. 165. INDICATIONS FOR USE • ICA- Anterior and posterior crowns and anterior three-unit FPDs. • ICS-Anterior single unit inlays, onlays, crowns and veneers. • ICZ-posterior crowns and posterior three-unit FPDs.
  166. 166. ADVANTAGES OF IN-CERAM Lack of metal. Relatively high flexural strength and toughness. Ability to be successfully cemented with any cement.
  167. 167. DISADVANTAGES • Marginal adaptation not very good. • Relatively high degree of opacity. • Inability to be etched. • Technique sensitive
  168. 168. Al2O3 slip Glass infiltration Giordono 1995 : Al2O3 Core glass infiltrated Ceramic > Strength than Hi-Ceram, Di-Cor & Feldspathic Porcelain
  169. 169. Working model In-Ceram application Shrinkage of dies Duplication Al2O3 slip In-Ceram refractory dies vita inceramat 120 0C- 2hrs Glass infiltration 4hrs 11000C
  170. 170. Finished InCeram copings (Air abraded) Application of body and incisal porcelain Preoperative veiw Finished crowns Postoperative veiw of In-Ceram crowns Probster et al : Strength of In-Ceram > IPS Empress < PFM
  171. 171. ZIRCONIA BASED SYSTEMS YTTRIUM TETRAGONAL ZIRCONIAPOLYCRYSTALS (Y-TPZ) BASED The most recent core materials for all-ceramic FPDs, (Y-TPZ) based materials were first used in orthopedics for total hip replacement, and were successful because of the material’s excellent mechanical properties and biocompatibility.It was introduced into dentistry in the early 1990s for using as implant abutments.
  172. 172. • As Y-TPZ core are glass free and because they have a polycrystalline microstructure they do not exhibit the phenomenon of sub critical crack propagation and stress corrosion caused by water in the saliva reacting with the glass.
  173. 173. • Y-TPZ based materials demonstrated a flexural strength of 900 to 1200 MPa and fracture toughness of 9 to 10 MPa.m ½. • It also demonstrated a fracture resistance of more than 2000 N under static load. JPD DEC 2004 ; 92:557-62 Contemporary materials and technologies for all ceramic fixed partial dentures: a review of literature
  174. 174. • Y-TPZ core is relatively translucent and, at the same time may mask the underlying discolored abutment. • Moreover it can be colored in 1 to 7 shades corresponding to the Vita- Lumin shade guide. • This ability to control the shade of the core may eliminate the need for veneering.
  175. 175. • Y-TPZ based core is radio-opaque which facilitates radiographic evaluation of the restoration. • Adhesive cementation is not mandatory and traditional luting agents may be used. • They also require relatively small connector area as compared to most other all-ceramic systems.
  177. 177. THE CERCON ZIRCONIA SYSTEM • Manufacturer-Dentsply Ceramco NJ • For posterior crowns and three unit FPDs • Fracture resistance of three unit FPD is 1278 N. (for ICA it is 514N and for Empress2 it is 621 N)
  178. 178. After preparing the teeth an impression is made and sent to the laboratory, where it is poured with a model material. A wax pattern approximately 0.8mm in thickness is made for each coping or crown areas of the framework of an FPD
  179. 179. The wax pattern is anchored on the holding appliance on the left side of the scanning and milling unit. A presintered zirconia blank is attached to the right side of the unit. After the unit is activated the blank is rough-milled and fine-milled on occlusal and gingival aspects in an enlarged size to compensate for the 20% shrinkage that will occur during subsequent sintering at 13500C. The processing time for milling is approximately 35 min for crowns and 80 min for a four-unit FPD.
  180. 180. • The zirconia copping is then placed in the Cercon furnace and fired at 13500C for 6 hrs to fully sinter the yttria stabilized zirconia core copping or framework. • The sintering shrinkage is achieved uniformly and linearly in the 3 dimensional space. • After any subsequent trimming with a water cooled highspeed diamond bur the finished ceramic core is then veneered with a veneering ceramic and stain ceramic.
  181. 181. Zirconia block Milled Block FPD framework tried on Working Cast
  182. 182. .......... • LAVA and Cercon systems use partially sintered blocks of Y- TZP for milling the framework, but DCM ( direct ceramic machining process ) uses fully sintered blanks or HIP (hot isostatically pressed blanks) Prague medical report vol 108 ( 2007) no 1 pg 5-12 : Zirconia- a new dental ceramic material
  183. 183. CONCLUSION No currently available restorative system can be considered the ideal replacement for natural tooth structure. However, in recent years there has been a great amount of attention given to research on and development of ceramic systems for restorative use. Ceramics are playing an increasingly important role in restorative dentistry, and further improvements in fracture resistance and wear properties will no doubt enhance their restorative use. The demand for esthetic dentistry is expected to continue and will be influencial in determining the range of the products available.
  184. 184. REFERENCES David A Graber, Ronald E Goldstein- porcelain and composite inlays and onlays esthetic posterior resorations. Aschheim Dale- esthetic dentistry 2nd edition Robert G Craig- restorative dental materials Phillips- science of dental materials 10th edition John McLean- the science and art of dental ceramics Pubmed 
  185. 185. THANK YOU