All ceramic materials

recent advances in ceramic

1. Presented by- Dr . Prerna chandak 1 st yr PG student CERAMICS 1 Ceramics

2. CONTENTS Introduction History of Ceramic Composition of Ceramic Properties Classification of Ceramic Method of strengthening Ceramic 2 Ceramics

3. Ceramic is derived from GREEK word “KERAMI KOS” meaning Burnt earth. Ceramic is therefore an earthy material, usually of a silicate nature. Introduction 3 Ceramics

4. According to GPT 9 Ceramic is defined as Compounds of one or more metals with a nonmetallic element, usually oxygen they are formed of chemical and biochemically stable substances that are strong , hard, brittle, and inert non-conductors of thermal and electrical energy . 4 Ceramics

5. Dental ceramics are attractive because of their biocompatibility, long-term colour stability, chemical durability ,wear resistance, and ability to be formed into precise shapes. 5 Ceramics

6. According to GPT 9 Ceramics 6 Porcelain is defined as Ceramic material formed of infusible elements joined by lower fusing materials most dental porcelains are glasses and are used in the fabrication of artificial teeth for dentures, pontics and facings, metal ceramic restorations, including fixed dental prostheses, as well as all ceramic restorations such as crowns, laminate veneers, inlays , onlays , and other restorations .

7. HISTORY & EVOLUTION OF CERAMICS 7 Ceramics

8. Ceramics 8 In 700 B.C., the Etruscans made artificial teeth of ivory , bone, human teeth, and animal teeth (possibly oxen). One of the first sets of dentures made for U.S. President George Washington contained extracted teeth but later his dentures were made of hippopotamus ivory.

9. The first porcelain tooth material was patented in 1789 by a French dentist de Chemant in collaboration with a French pharmacist Duchateau . The first ceramic crowns and inlays were made by C.H.LAND in 1886. He fused feldspathic to burnished platinum foil. 9 Ceramics In 1962, Weinstein patented a leucite -containing porcelain frit for use in metal-ceramic restorations.

10. The first commercial porcelain was developed by Vita Zahnfabrik in about 1963. The popularity of all ceramic systems increased after the introduction of alumina reinforced dental porcelain by McLean and HUGHES in 1965 . 10 Ceramics

11. Composition of ceramic 11 Ceramics

12. 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 12 Ceramics

13. 5.Fluxes – Glass modifiers 6.Colour pigments 7.Opacifying agents 8.Stains and colour modifiers 13 Ceramics

14. Silica is the basic structural unit of the glass network Silica (SiO2): crystalline quartz, crystalline cristobalite , crystalline tridymite , and noncrystalline fused silica. Silica 14 Ceramics

15. Fluxes (low-fusing glasses) are often included to reduce the temperature required to sinter the porcelain powder particles at sufficiently low temperatures so that the alloy to which it is fired does not melt or sustain sag (flexural creep) deformation. Fluxes 15 Ceramics

16. Boric Oxide fluxes Boric Oxide (B 2 O 3 ) although a powerful flux (glass modifier), it can also act as a glass former and form its own glass network, producing Boron Glasses. 16 Ceramics

17. Glass Modifiers Can be defined as elements that interfere with the integrity of the SiO 2 (glass) network and alter their three-dimensional state. Their functions are: To decrease the softening point by reducing the amount of cross linking between oxygen and glass forming elements. Decrease the viscosity (flux action increasing the flow ) 17 Ceramics

18. Hydrated aluminium silicate Its functions are: Acts as a binder It gives opacity to the mass 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. Kaolin ( White China Clay) 18 Ceramics

19. Feldspars Types of feldspar : Soda feldspar – Decreases fusion temperature Potash feldspar – Increases the viscosity of glass . 19 Ceramics

20. Role of feldspar 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. Leucite formation: Another important property of feldspar is its tendency to form the crystalline mineral leucite . 20 Ceramics

21. Leucite Is a potassium- aluminum -silicate mineral with a high coefficient of thermal expansion ( 20-25x10 C) compared to feldspathic glasses ( 10x10 C). Feldspar heated at temperature of 1150 c and 1530 c it undergoes incongruent melting. 21 Ceramics

22. 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 Ceramics

23. Intermediate Oxides/ Glass former 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 (Al 2 O 3 ), to increase the viscosity of glass. 23 Ceramics

24. Colouring agents Dental porcelains coloured by the addition of concentrated colour frits which are prepared by fritting high temperature resistant colouring pigments (generally metallic oxides) into the basic glass. 24 Ceramics

25. The colour pigments used are: Yellowish brown – Titanium oxide Blue - Cobalt salts in the form of oxide Green - Copper oxide Brown- nickel oxide/iron Lavender- manganese oxide 25 Ceramics

26. Opacifying agents The common metallic oxides used are – Cerium oxide Titanium oxide Zirconia oxide 26 Ceramics

27. Tin oxide and Zirconium oxide (ZrO 2 )- most popularly used opacifying agent (usually added with the concentrated colour frit to the porcelain during final preparation. 27 Ceramics

28. Dental ceramic Classification According to sintering temperature High fusing > 1300 C Denture teeth Medium fusing 1101 –1300 Low fusing 850 – 1101 C crown& bridge Ultra low fusing <850 C. 28 Ceramics

29. ACCORDING TO TYPE: Feldspathic porcelain Aluminous porcelain Glass infiltrated aluminous Glass infiltrated spinel Glass ceramics 29 Ceramics

30. ACCORDING TO USE Ceramic for artificial teeth Jacket crown, inlay and onlay ceramic Metal ceramic Anterior bridge ceramic 30 Ceramics

31. ACCORDING TO SUBSTRATE MATERIAL Cast metal Sintered metal Swaged metal Glass ceramic CAD/CAM.   31 Ceramics

32. Currently available all-ceramics can be broadly categorized according to their method of fabrication 32 Ceramics

33. Properties of porcelain The characteristic properties of porcelain are hardness, compressive strength, esthetic, opacity, translucency. Low to moderate fracture toughness. Refractory nature Insoluble in oral environment. Extremely biocompatible. Resistance to thermal and chemical attack. 33 Ceramics

34. Flexural strength Ground porcelain 75.8 Mpa Glazed porcelain 141.1 Mpa Compressive strength 331 Mpa Tensile strength 34Mpa Shear strength 110 Mpa 34 Ceramics

35. Disadvantages The major weakness of ceramics is their inability to flex and to fracture at a minimum deformation of 0.1%. Brittleness is its biggest disadvantage and a major disadvantage to porcelain is decreased tensile strength. Another major drawback is the potential to cause abrasive wear on the opposing dentition. 35 Ceramics

36. Methods of strengthening brittle materials 1.Ion exchange 2.Thermal tempering 3.Thermal compatiability Minimise stress concentration Reducing stress raisers Minimise tensile stresses Residual compressive stresses Interruption of crack propagation Addition of dispersion phase Change in crystalline structure Particle stabilized zirconia Toughness of particle Al umina , leucite 36 Ceramics

37. Ion exchange/ chemical tempering . Potassium ion is about 35% larger than the Sodium ion. Which Increases flexural strength of feldspathic porcelains. 37 Ceramics

38. THERMAL TEMPERING Rapidly cooling the surface of the object while it is hot and in the softened (molten) state. As the molten core solidifies, it tends to shrink, but the outer skin remains rigid which create residual compressive stress. It is more effective to quench hot glass-phase ceramics in silicone oil or other special liquids. 38 Ceramics

39. Thermal Compatibility 39 Ceramics The metal ceramic should be selected with a slight mismatch in their thermal coefficient. So that the metal contract slightly more than ceramic on cooling from the firing temperature to room temperature . This mismatch leaves the ceramic in residual compression and provide additional strength for the prosthesis .

40. Transformation toughening 40 Ceramics When small tough crystals are homogenously distributed in the glass, the ceramic structure is strengthened because cracks cannot penetrate the fine part as easily as they can penetrate the glass. Various dispersed crystalline phase include alumina , leuite , tetrasilicic fluoromica , lithia disilicate and magnesium alumina spinel .

41. When zirconia is heated between 1470-2010 o C and cooled to room temperature its crystal being to change from tetragonal to monoclinc phase at about 1150 o C . During heating there is large volume expansion and high tensile stress this causes zirconia to crack during cooling. Additives like 3 mol% yttrium oxide can prevent this polymorhic transformation 41 Ceramics

42. 42 Ceramics

43. METAL CERAMIC RESTORATIONS Ceramics 43 The metal-ceramic restoration first became available commercially during the later 1950. The metal-ceramic restoration consists of a metal substructure supporting a ceramic veneer that is mechanically and chemically bonded .

44. Ceramics 44

45. Ceramics 45 c c

46. Ceramics 46

47. Three factor control the durability of metal -ceramic bonding Ceramics 47

48. Failure of metal ceramic crown Ceramics 48

49. Advantages Ceramics 49 Better fracture resistance because of the metal reinforcement. Better marginal fit because of the metal frame .

50. Disadvantages Ceramics 50 Comparatively less esthetic (when compared to the all porcelain crown) because of the reduced translucency as a result of the underlying metal and the opaque . Margins may appear dark because of the metal. This sometimes shows through the gingiva causing it to appear dark and unesthetic

51.   Compared to Metal-ceramics, the advantages of All-ceramic restorations include: 51 Ceramics

52. Newer types of All Ceramic Restorative Materials 52 Ceramics

53. CONVENTIONAL POWDER/ SLURRY CERAMICS 53 Ceramics

54. (1965 Mc lean and Hughes) 40 t0 50 wt% of Al2O3 (interrupt crack propagation) Feldspar Quartz kaolin Flexural strength 131 Mpa ALUMINOUS CORE PORCELAIN (Hi-Ceram )

55. Finished Cores Master model with dies Platinum foil adapted to die Platinum foil adapted to die Platinum foil technique ALUMINOUS PORCELAIN

56. Unsintered Crowns Dentin Ceramic additions Finished Crowns on dies Post-Cementation ALUMINOUS PORCELAIN

57.        Advantages     Fracture Resistance in the aluminous PJC improved platinum matrix was left in the completed but diminished esthetic. . Disadvantage Low coefficient of thermal expansion in the range of 8 x 10 -6 / C. Requires specially formulated and compatible enamel and dentin porcelains for veneering. 1) Improvement in strength is insufficient to bear high stresses Decrease the amount of light transmitted

58. Magnesia – Reinforced Porcelain O’Brien in 1984 H igh expansion ceramics Core material. Crystalline magnesia (40-60%) ‘ Forsterite ’. M agnesia crystals strengthen glass matrix by both dispersion strengthening and crystallization within the matrix . F lexural strength (131 Mpa ) Glazed strength (269 MPa )

59. ADVANTAGE : Increased co-efficient of thermal expansion Improved strength ( glass infiltration of magnesia core )

60.   FELDSPATHIC PORCELAINS. Leucite crystals in the glass - matrix (50%). Condensed and sintered on a refractory die. Strength nucleation and growth of leucite crystals. Transluceny closeness of the refractive index of leucite with that of the glass matrix F lexure strength is approximately 140 MPa .. LEUCITE – REINFORCED PORCELAINS Optec HSP

61. Advantages H igh strength despite of metal( leuicte reinforcement) Good translusency Moderate flexural strength Disadvantage M arginal inaccuracy(shrinkage). Fracture in posterior teeth. High abrasive effect on opposing teeth.

62. HYDRO THERMAL CERAMICS Ryabov et al--1970 Low fusing ceramics + hydroxyl groups ( plastified layer) Melting , softening point, sintering temperatures were reduced Thermal expansion , strength-----not compromised Self healing effect- --micro flaws Formulations: single phase porcelain leucite containing two phase material

63. DISADVANTAGES : C annot be directly sintered on metallic substructure .Inner lining of conventional high-fusing ceramic is required on the metal substructure because of the low coefficient of expansion.

64. DUCERAM LFC FABRICATION: Duceram MC -----base layer-----930 c Duceram LFC- -----660 c-----no glaze required Fabrication : Refractory die----mc slurry(930)-----LFC(660)----no glaze . GOLDEN GATE SYSTEM: G old alloy + ducera LFC DUCERA GOLD: T ype IV gold + ducera LFC HYDRO THERMAL CERAMICS

65. Advantages: Lower fusion temperature (680-700 C) Increased coefficient of thermal expansion Minimal abrasion of opposing dentition( natural teeth) Greater toughness and durability Greater density Higher flexural strength attributed to OH - ion exchange and sealing of surface microcracks Greater fracture resistance Surface resistant to chemical attack by fluoride containing agents. Highly polishable , not requiring re-glazing during adjustment

66. CASTABLE CERAMICS

67. Castable glass-ceramic systems was developed by Corning glass worker and introduced by Dentsply international. Castable glass that is formed into an inlay, facial veneer or full crown by lost wax process similar to that employed for metals. Glass ceramic ( Dicor ) 67 Ceramics

68. Glass casting core/ coping Crystal nucleation & growth… - veneering porcelain Glass + covered by protective embedment material Heat treatment / ceramming 68 Ceramics

69. Casting techniques similar to the conventional lost wax technique used for cast-metal restorations. Excellent marginal fit. The wear on the opposing occlusion is predicted to be less than that of conventional porcelains. Flexural strengths is 172 Mpa reportedly greater than it is for conventional porcelain. ADVANTAGES 69 Ceramics

70. Most Translucent of all the all-ceramic materials. However color must be developed using several coats of surface glaze, or Dicor must be veneered with porcelain. Dicor , because of its high translucency, has a chameleon- like effect and merges with the surrounding teeth. 70 Ceramics

71. Once stained, the surface cannot be adjusted without compromising the esthetics. The colorant is a surface stain, hence any grinding on the restoration leaves an unaesthetic opaque white area. Removal of the external cerammed layer has been reported to affect the flexural strength. Technique sensitive. DISADVANTAGES 71 Ceramics

72. INFILTERED CERAMICS

73. Flexural strength 350 MPa 500 MPa 700 MPa In- ceram Alumina In- ceram Spinel In- ceram Zirconia INFILTERED CERAMICS The final In-Ceram structure consists of two 3-dimensionally interpenetrating phases : crystalline phase- alumina , magnesia,zirconia . Glassy phase

74. A process used to form green ceramic shape by applying a slurry of ceramic particles and water or a special liquid to a porous substrate Such as a die material, there by allowing capillary action to remove water and densify the mass of deposited particles IN-CERAM ( Vident ) ( Slip casting technique ) SAADOUN 1985- --FRANCE

75. Composition: Alumina / Al 2 3 crystalline (Volume fraction) 99.56 wt% with particle size 3.8  m An Infiltration glass lanthanum aluminosilicate with small amounts of sodium and calcium (Lanthanum-decreases the viscosity of the glass to assist infiltration and increases its refractive index to improve translucency). Fabrication stages : Slip casting Veneering of core INCERAM ALUMINA

76. Duplication In-Ceram refractory dies In-Ceram application Working model INCERAM ALUMINA

77. Al 2 O 3 slip 10 hrs 1120 C - vita inceramat Shrinkage of dies Glass infiltration 4hrs 1100 C

78. Application of body and incisal porcelain Postoperative veiw of In-Ceram crowns Finished In-Ceram copings Finished crowns Preoperative veiw

79. VENEERING OF CORE Aluminous veneering porcelain ( Vitadur N, Vident ) of required shade is applied by conventional powder-slurry method . Final firing is followed by adjustments and glazing of external surface . The internal surface is sandblasted (with 50  Al 2 O 3 ) since the density of In-Ceram core makes conventional methods of etching with HF acid ineffective for bonding with a resin-cement.

80. PROPERTIES STRENGTH : The densely packed crystalline particles (70% alumina) limit crack propagation and prevent fracture. The flexure strength is extremely high in the 450 MPa range (the strongest all-ceramic dental restoration presently available).

81. COLOR : The final color of the In-Ceram restorations is generally influenced by the color of the alumina core, which tends to be opaque. The colorants used generally consist of transitional metal ions incorporated into the glass structure itself. However , in the spinel variety, the core is more transparent and its corresponding infiltration glass is slightly tinted.

82. USES : Single anterior & posterior crowns Anterior 3-unit FPD's   ADVANTAGE : Minimal firing shrinkage, hence an accurate fit. High flexure strengths (3 times). Aluminous core being opaque can be used to cover darkened teeth or post/ core. Wear of opposing teeth is lesser Improved esthetics due to lack of metal as substructure. Biocompatible, diminished plaque accumulation , .

83.   DISADVANTAGES: Requires specialized equipment. Poor optical properties or esthetics (opaque alumina core ). Incapability of being etched . Slip casting is a complex technique and requires considerable practice. Considerable reduction of tooth surface

84. Improvement in optical properties Incorporating magnesium- alumina spinel ( Mg Al 2 O 4 ) ( translucency) Fabrication: similar to In-Ceram crowns IN-CERAM SPINELL

85. Ceramics 85 Advantage Spinel renders greater strength characteristics. Spinel has extended uses(Inlay / Onlay , ceramic core material and even Veneers.) spinel exhibited better translucency than alumina

86. Disadvantage: Incapable to be etched by HF. 25% reduction in flexural strength .

87.   M ixture of zirconium oxide 20% aluminia 62% and 18% infiltrated glass is a framework material improved physical properties . PROPERTIES : High flexural strength ( 1.4 times the stability 2-3 times impact capacity compared to ln -Ceram Alumina), Excellent Marginal Accuracy Biocompatibility. IN-CERAM ZIRCONIA

88. Ceramics 88 This technique allows fabrication of all-ceramic bridges even in the posterior molar area. Disadvantage : Poor esthetics due to increased opacity.

89. PRESSABLE CERAMICS

90. SHRINK FREE LEUCITE REINFORCED cerestore IPS E mpress al – ceram optec pressable PRESSABLE CERAMICS INJECTION MOLD GLASS CERAMIC

91. Ceramics 91 CERESTORE is a shrink-free ceramic with crystallized magnesium alumina spinel fabricated by the injection molded technique to form a dispersion strengthened core. Composition (Core) Al 2 O 3 (Corundum) 60% MgAl 2 O 4 ( Spinel ) 22% BaMg 2 Al 3 (Barium Osomilite ) 10%

92. Properties : Flexural strength : 225 Mpa Fit : exceptional fit because of direct moulding process. Low thermal conductivity Radio density similar to enamel Biocompatible CERESTORE

93.   Advantages Dimensional stability of the core material in the molded (unfired) and fired states. Esthetics . Biocompatible (inert) and resistant to plaque formation (glazed surface). Radio density similar to that of enamel (presence of barium osmolite phase in the fired core allows radiographic examination of marginal fit ) CERESTORE

94. Ceramics 94 Low thermal conductivity. Low coefficient of thermal expansion and high modulus of elasticity results in protection of cement seal Better accuracy of fit and marginal integrity.

95.       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 .). CERESTORE

96. IPS-EMPRESS (PRESSABLE CERAMIC ) Hot pressed ceramics Leucite reinforced K 2 O – Al 2 O 3 – 4 SiO 2 Lithium Disilicate reinforced 2SiO 2 – Li 2 O IPS Empress IPS Empress 2

97. Pressable glass ceramics Injection-molded Glass-Ceramic IPS Empress ( Ivoclar-Vivadent ) This system uses high-temperature pressing of a pre- cerammed glass ceramic with hydrostatic pressure in a vaccum unit.

98. PROCEDURE

99. Empress hydrostatically controlled furnace Cold burnout oven—850 C/90mins . Precerammed pellets

100. Pneumatic plunger Maintains hydrostatic pressure 1,100 C /45mins. under vacuum

101. Pressed ceramic restorations are cleaned with a glass bead air abrader.

102. STAINING SURFACE STAINING TECHNIQUE Shading porcelains in syringes Restoration painted & fire(850DC/2min) using vacuum.

103. Ceramics 103 Disadvantages Complex specialized laboratory equipment and cost. Inadequate flexural strength compared to the metal-ceramic restorations. Poor abrasion resistance, hence not recommended in patients with heavy bruxism or inadequate clearance.

104.   Leucite content Conventional Porcelain Dicor IPS Empress Pressable ceramic 30-35% 50-60% 80-85%

105. Properties : Flexural strength : 160-180 Mpa The increase in strength has been attributed to : The pressing step which increases the density of leucite crystals. Subsequent heat treatments which initiate growth of additional leucite crystals. Esthetics : High esthetic value Marginal adaptation : Better marginal adaptation compared to aluminous core material.

106. Advantages Lack of metal or an opaque ceramic core Moderate flexural strength (120-180 MPa range) Excellent fit (low-shrinkage ceramic) Improved esthetics (translucent, fluorescent) Etchable

107. Ceramics 107 Less susceptible to fatigue and stress failure Less abrasive to opposing tooth Biocompatible material Unlike previous glass-ceramic systems IPS Empress does not require ceramming to initiate the crystalline phase of leucite crystals (They are formed throughout the various temperature cycles).

108. Disadvantages Potential to fracture in posterior areas. Need for special laboratory equipment such as pressing oven and die material ( expensive) Inability to cover the color of a darkened tooth preparation or post and core, since the crowns are relatively translucent . Compressive strength and flexural strength lesser than metal-ceramic or glass-infiltrated (In-Ceram) crowns.

109.          Second generation of pressable materials for all-ceramic bridges. lithium disilicate crystal >60vol%. The apatite crystals -layered-improved optical properties (translucency, light scattering) which contribute to the unique chameleon effect I P S EMPRESS 2 ( Ivoclar )

110.   IPS Empress IPS Empress 2 Flexural strength   Upto 150 MPa > 400 Mpa Other applications : - Core build-up system with the pre-fabricated zircon oxide root canal posts .

111. Ceramics 111 Advantages High biocompatibility Excellent fracture resistance High radiopacity Outstanding translucency

112. Ceramics 112 The cerammed restorations have a high degree of stability during subsequent shading or layering techniques. The pre- cerammed porcelain has a high degree of flexural tensile strength (exceeding 200 MPa ). The versatility of the process allows for the development of very esthetic restorations ranging from inlays & onlays to full crowns and laminate veneers (1mm). Posterior teeth- fracture susceptibility need to use special, expensive lab. equipment.

113. References 1.CONTEMPORARY FIXED PROSTHODONtic -ROSENSTIEL 2.PHILLIPS SCIENCE OF DENTAL MATERIALS -ANUSAVICE 3.FUNDAMENTALS OF FIXED PROSTHODONTICS -SCHILLINGBURG 4.CONTEMPORARY ESTHETIC DENTISTRY : -BRUCE J.CRISPIN 5.ESTHETIC DENTISTRY: AN ARTISTS SCIENCE RATNADEEP PATIL -