Dental ceramics / orthodontic seminars


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Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.

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Dental ceramics / orthodontic seminars

  1. 1. Dental ceramicsDental ceramics Silicate ceramics and oxidceramicsSilicate ceramics and oxidceramics INDIAN DENTAL ACADEMY Leader in continuing dental education
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  8. 8. Images from KaVo Everest CAD/CAM system
  9. 9. Why use ceramics           Biocompatibility  Aesthetics  Durability The biocompatability issue is essential to prevent adverse  reactions within the patients  The use of dentally coloured glasses can provide  replacement structures that can be made to imitate tooth  structure in both colour, translucency and response to  different lighting sources. Improvements in fracture toughness, wear resistance,  machinability, solubility and flexural strength
  10. 10. Ceramics used in dentistry  Fillings  Veneering metal frameworks  All ceramic restorations  Denture teeth  Implants  Orthodontic brackets
  11. 11. Silicate ceramics ESTHETICS  Feldspathic porcelain Veneering ceramics – sintering      Glass Ceramic Castable glasses-Dicor Pressed leucite system-  IPS Empress  Oxid ceramics STRENGTH  Glass infiltrated Alumina  system In-ceram Alumina In-Ceram Spinell In –Ceram Zirconia  Policrystal  ceramics:CAD/CAM Cercon Base DC-Zirkon Lava Frame
  12. 12. Glass matrix   +   Crystals An overcooled  liquid Not crystalline, but  still ordered structure Silica tetrahedron  network Glass modifiers  built in network Most important crystals:  Leucit  Fluormica  Aluminium  Spinell  Zirconia They determin the  physicalphysical, chemicalchemical and opticaloptical properties of the ceramics (their composition varies in each type of ceramic) Basic structure of dental ceramics Two different phases built by metallic (Al,Ca, Mg, K etc) and non-metallic (Si, O,  B, F etc.) elements:
  13. 13. First ceramic material in dentistry Feldspathic Porcelain: derived from the natural mineral feldspar   75%feldspar,22-25% quartz, 0-3% kaolin  Feldspar: Provides for transparency and influences the flow characteristics of the  ceramics.  Quartz (silicon oxide): Provides for adequate strength and also for transparency.  Kaolin: Provides for the necessary opaque properties.  Fritting:-cleaning and mixing raw materials, heating, melting, sudden  cooling and grinding to fine powder  Sintering:powder mixing with liquid, firing, powder particles stick  together  Shrinkage:appr. 30 vol%  Structure: leucite crystals in silica glass matrix  Disadvantage:brittle,hard,
  14. 14. Image from Bego Virtual Academy Veneering metal frameworks
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  16. 16. Image from Bego Virtual
  17. 17. Metal-ceramic restorations: •Ceramic material is veneered (sintered) onto a metal frame in several firing processes Esthetic consideration
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  21. 21. Veneering ceramics  Used for the porcelain-fused-to-metal technique  Based on modified feldspathic porcelain  Binding oxides for metal-ceramic bond  Leucite content:thermal expansion coeff.  Fusing temperature 200-250 C lower than metal framework (low fusing ceramics) Synthetic ceramics (metal –ceramics) No natural raw materials Made of high purity chemicals Tempering:guided heating process, to form certain type, size, amount and dispersion of crystals (micro-leucite crystals Standard physical, chemical and optical properties Standard quality Low or ultra-low fusing temperature Hydrothermal ceramics • tempering and fusing in high pressure steam • Hydroxil ions built in glassy matrix • Compact and homogenous structure • Better fracture toughness and lower hardness • Leucite content allows veneering frameworks • Ultra-low fusing temp. Can be achieved • Pure glass can be used for dental purposes (one and only among dental ceramics)
  22. 22. The bonding of ceramic materials to alloys follows four principles:  Shrinking the ceramic onto the metal frame - coefficient of thermal expansion  Chemical bond The bond is formed by means of oxygen bridges between the silicon atoms of the ceramic and the metal oxides of the alloy.  Mechanical retention is created through finishing and blasting of the frames-surface enlargement also takes place.  Bonding through adhesion takes place via intermolecular forces (VAN DER WAAL forces)
  23. 23. All ceramic restorations
  24. 24.  driving forces for developments:  Public perception that metal-free restorations are more aesthetic  Disadvantages of the metal ceramic systems include radiopacity, some questions centring around metal biocompatibility and lack of natural aesthetics  Difference in reliability between metal-ceramic systems and all-ceramic systems
  25. 25. All ceramic restorations Laboratory processing  Silicate ceramics o Sintering o Casting o Pressing o CAD/CAM  Oxidceramics o infiltration and /or CAD/CAM technology
  26. 26. SinteringSintering is a method for making objects from powder, by heating the material (below its melting point) until its particles adhere to each other The base-material for heating ceramic on:The base-material for heating ceramic on: - platinum foilplatinum foil (removable heat-resistant cap from the gypsum cast) - Heat resistant investment material madeHeat resistant investment material made castcast - Hydrothermal glass/ Duceram LFCHydrothermal glass/ Duceram LFC SinteringSintering under vacuumvacuum to prevent
  27. 27.  Casting (Dicor) CastingCasting is a process by which a material is introduced into a mold while it is liquid, allowed to solidify in the shape inside the mould, and then removed producing a fabricated object Cast using lost-wax investment method followed by heat-treatment to precipitate a crystalline phase  Pressing (Empress) PressedPressed ceramic technology produces consistently precise crowns by eliminating shrinkage, porosity and the inconsistency of brush
  28. 28. Glass Ceramic  first a glassy matrix is produced  precursors of crystals are in glassy matrix, crystals produced by tempering (heating),  “bonded” to the remaining tooth structure using a dental BisGMA based composite resin
  29. 29. Glass infiltration Oxidceramics  Glass infiltrated Alumina system In-ceram Alumina In-Ceram Spinell In –Ceram Zirconia Slip-cast slurry in porous mould-sintered — infiltration by low viscosity glass — veneered with more translucent feldspathic frit Slip-cast slurry: A fine particle ceramic dispersed in an aqueous liquid medium is poured into a porous mould which rapidly extracts the liquid causing the formation of a close-packed but weak ceramic particle
  30. 30. Polycrystal Oxid ceramics  High strength underlying core to support veneering porcelain which gives the final shape and aesthetic attributes required for the restoration.  Yttrium stabilized Zirconium -dioxide ceramics: ZrO2 95%+ 5% Yttrium More to come: lecture on CAD/CAM systems
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