Ceramic

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  • Or semi metallicSemi( aluminum, ca, zirco,titanium, Na, Tin, silicon)
  • Ceramics can be classified onto 4 categories
  • Silicone dioxideAluminum OxideMagnesium OxideZirconium Dioxide ( zirconia)
  • BoridesCarbidesnitrides
  • Dicor Glass ceramic
  • Liquids, gases and ACIDSzrO2 – one of the strongest ceramics Steel gretaer fracture toughness than zirconia
  • Am, co, cements have been used w/ good success but they are not IDEAL for large resto or FPDSo you need: maintain surface quality and esthetics over long periods of timeAlthough : costly machines / special training
  • UseCompositionProcessingFiringMicrostructureTranslucencyFracture resistanceAbrasiveness
  • Feldspar- mineral; contains potash- K2O, soda Na2O, alumina (al2O3) and silica, colorlessKaolin- white clay like materialQuartz- form of silica; acts as refractory skeleton providing strength and hardnessAlumina- gives strength and opacity also; alters softening point and increases the viscosity of porcelainGlass modifiers- lower fusion temp and increase flow of porcelain
  • Firing- process of sintering and fusing the particles of the condensed massMed & high – denture tthLow&ultra- crown and bridge
  • In the mineral state..Potassium aluminum silicate
  • Pigment-simulate natural teethOpacity can be achieved by.. ZrO2.. Tin oxide
  • MC - Not for max ant tth- Concern when ging recession occursC – fracture posterior
  • MC or all ceramic are supplied asLess prorsity in fired porcelainPic- condensation of por slurry on metal framewirk for 4 unit FPD
  • After porcelain has been applied and condensedDries too quikcly – faster evap rate than diffusion
  • . specified temp – below melting pt of the main component
  • Autoglazed or self glazedStains- more life like
  • Because of this composition, it may be considered as glass
  • Comp aided design and comp aided manufacturing
  • Widely used
  • Ceramic

    1. 1. CERAMICDental Materials
    2. 2. DEFINITIONS• Ceramic –• An inorganic compound w/ non metallic properties typically composed of metallic and non metallic elements• Dental ceramic –• An inorganic compound w/ non metallic properties typically composed of O2 and 1 or more metallic or semi metallic elements that is formulated to produce the whole part of a ceramic based dental prosthesis
    3. 3. 4 categories of ceramics1. Silicate Ceramics2. Oxide Ceramics3. Nonoxide Ceramics4. Glass Ceramics
    4. 4. Silicate Ceramics• Amorphous glass phase with a porous structure• Main components:• SiO2• Small quantities of :• Al2O3• MgO• ZrO2 Dental porcelain
    5. 5. Oxide Ceramics• Principally contains:• Al2O3,MgO,ZrO2 with either no glass phase or small content.
    6. 6. Non oxide Ceramics• Impractical for dental use• Why?• High sintering temp• Unesthetic color• opacity
    7. 7. Glass Ceramics• Are partially crystallized glass• Produced by nucleation and growth of crystals in glass matrix phase
    8. 8. Dental ceramics• May consist primarily of :• Glasses , glass ceramics or highly crystalline structures• Ceramics are more resistant to corrosion than plastic• Remain stable for a long period of time• Do not react with most liquids, gases• Excellent – fair fracture toughness• Zirconium dioxide> Flexural strength similar to steel
    9. 9. Dental ceramics• Biocompatible• Long term color stabbility• Wear resistance• Ability to be formed into precise shapes
    10. 10. Phillips Dental MaterialsCLASSIFICATION OF DENTALCERAMICS
    11. 11. Dental ceramics can be classified according to :• Use or Indication- Anterior- Posterior- Crowns- Veneers- Post and cores- FPDs- Stain ceramics- Glaze ceramics
    12. 12. • Composition- Pure alumina- Pure zirconia- Silica glass- Leucite-based glass ceramic- Lithia based glass ceramic
    13. 13. • Processing method- Sintering- Partial sintering- Glass infiltration- CAD CAM- Copy milling
    14. 14. • Firing temperature- Low fusing- Medium fusing- High fusing
    15. 15. • Microstructure- Glass- Crystalline- Crystal containing glass
    16. 16. • Translucency- Opaque- Tranlucent- transparent
    17. 17. • Fracture Resistance• Abrasiveness
    18. 18. Metal Ceramic Prosthesis• COMPOSITION OF DENTAL PORCELAINS• Most dental porcelains consist of• Kaolin• Silica• Feldspar• Glasses
    19. 19. Glass modifiers• Manufacturers employ glass modifiers to produce dental porcelains with different firing temperatures Categories Firing temperature High fusing 1300oC or above Medium fusing 1101 to 1300oC Low fusing 850 to 1100oC Ultra low fusing < 850oC
    20. 20. Feldspathic Porcelains• Feldspar- main ingredient of classical metal ceramic porcelain. ( crystalline and opaque)• Chemically designated as K2O.Al2O3.6SiO2• These ceramics are called porcelains because they contain a glass matrix and one or more crystal phases.
    21. 21. Other Additives• B2O3 ( Boric Acid) – behaves like a glass modifier• Alumina – not a true glass modifier but can alter softening temperature and viscosity• Pigmenting oxides – natural shade of tooth• Iron or nickel oxide – brown• Copper oxide – green• Titanium dioxide – yellowish brown• Manganese oxide – lavander• Cobalt oxide – blue• Opacity– zirconium oxide, tin oxide
    22. 22. Esthetic potetialMetal ceramic All Ceramic• 70% of all fixed restorations • Matches appearance of• Not the best esthetic choice adjacent natural tooth• Dark line at facial margin • More susceptible to fracture • Ceramic margin
    23. 23. Porcelain Condensation• Supplied as a fine powder to be mixed with water or another vehicle and condensed into desired form• Dense packing has 2 benefits:1. Lower firing range2. Less porosity• Packing may be achieved through1. Vibration2. Spatulation3. Brush technique
    24. 24. Drying• The restoration is placed in an open furnace to be dried.• Until 480 deg C is reached• Drying stage – 5- 8 minutes• Ensures the remaining water is removed• Dries too quickly – spontaneous breakage• If wet structure is placed onto firing in hot furnace – steam-crumble-explode
    25. 25. Sintering of porcelain• The purpose of firing :• To sinter the particles of powder together properly to form the prosthesis.• Sintering – process of heating closely packed particles to a specified temp to densify and strengthen a structure• After porcelain is preheated, firing cycle is initiated.
    26. 26. Overglazing and shading• Natural glazed porcelain is much stronger than ground, rough, non glazed porcelain.• Glaze – effective in reducing crack propagation within the outer surface.• Stains and glazes
    27. 27. Cooling of metal-ceramic prosthesis• Sudden changes in temperature – fracture• Slow cooling followed by slow opening of furnace door
    28. 28. Benefits and drawbacks of metla ceramics• Stronger and more durable than all ceramic crowns• Permanent aesthetic quality• Fracture resistance• No abrasion wear• No staining along metal and veneer interface• Less tooth structure is removed to provide proper bulk for the crown.
    29. 29. Ceramics for Ceramic Metal Restorations• 5 requirements:1. Must simulate appearance of tooth2. Fuse at low temp3. Must have compatible thermal expansion with metals4. Must withstand oral environment5. Must not abrade opposing teeth
    30. 30. Ceramics for ceramic metal restorations• Ceramics are composed of crystalline phases in an amorphous , glassy vitreous matrix.• Glass• They fuse at a lower temp , to prevent metal from distorting
    31. 31. ALL CERAMIC PROSTHESIS
    32. 32. • Castable and machinable glass ceramics• Pressable glass ceramics• Slip cast All ceramic ceramics• Procera Allceram• CAD CAM ceramics
    33. 33. GENERAL APPLICATIONS OFCERAMICS IN DENTISTRY
    34. 34. • Ceramics are the best materials to match esthetic complexity of human teeth• Used for ceramic metal crown• FPD• All ceramic resto• To fabricate denture teeth
    35. 35. Ceramic metal crowns• ADVANTAGE:• Better abrasion resistance• More durable• Better adhesion with resin cements• DISADVANTAGES:• Occlusal adjustment is more difficult• Not for high stress areas
    36. 36. All Ceramic Crowns, inlays , veneers• Ceramic veneer – layer of ceramic bonded to the facial surface of a prepared tooth to cover any defaults.• Custom made , fabricated in lab.

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