1. Floating Topic
2. Floating Topic
3. Floating Topic
4. Composition & Properties
   1. Composition
      1. fabrication
         1. 3 raw ingredients
            1. feldspar
            2. silica
            3. alumina
            4. heated together with fluxes (eg sodium carbonate/ potassium carbonate
         2. fluxes
            1. disrupt crystal lattices
            2. promote formation of amorphous glass that melts at low temp
         3. dental porcelain is thus a matrix of
            1. low melting
            2. amorphous
            3. noncrystalline glass
            4. with leucite crystal embedded in it
         4. metal oxide is then refired to this porcelain
            1. add colour & fluorescence
         5. after cooling
            1. ground to fine powder
            2. use in dental lab
      2. in dental lab
         1. powder (with appropriate shades)
            1. mix with water/ gycerol-water solution
         2. apply powder-liquid slurry onto alloy substructure
         3. liquid is removed by vibration& absorption
            1. condensed & strengthen porcelain
            2. "green" state
         4. fired in oven
            1. causing the borders of particles melt & fused together
            2. "sintering"
   2. Properties
      1. classified by Fusing/sintering temperature
         1. High fusing
            1. 1288-1371*C
            2. denture teeth
         2. medium fusing
            1. 1093-1260*C
            2. PJC
         3. low fusing
            1. 871-1066*C
            2. MCC. FCC
      2. Flexural strength
         1. ability to resist # when loaded from above
            1. influenced by
            2. compressive strength
            3. tensile strength
      3. Coefficient of thermal expansion
         1. amount of expansion/contraction in response to heating/cooling
         2. if high
            1. ceramic expand and contract a large amount when heating/cooling
         3. Important
            1. when bonded to alloy/ceramic core
      4. Hardness
         1. Harder than human enamel
            1. when occlude, will wear opposing enamel
      5. colour
         1. Munsell system
            1. Hue
            2. basic shade of colour
            3. eg yellow,green,blue
            4. Chromma
            5. intensity of colour/ "greyness"
            6. eg, pale blue, dark blue
            7. Value
            8. amount of lightness/darkness
5. Ceramic-alloy restorations
   1. Ceramic-alloy bonding
      1. traditional ceramic
         1. Too brittle
         2. high failure rate
      2. Bonding to alloy
         1. Through an oxide on alloy surface
         2. chemical reaction btw oxide layer & ceramic
      3. Failure of bonding
         1. inadequate oxide layer on alloy
            1. weak ceramic-alloy bond
         2. oxide layer too thick
            1. oxides themselves are brittle
            2. risk of fracture
         3. MOST COMMON
            1. failure within ceramic layer itself
            2. near alloy-ceramic interface
      4. proper match of coefficient of thermal expansion of ceramic & alloy
         1. Ceramic should have COTE slightly less than alloy
            1. ceramic will expand/contract less during heating/cooling
         2. when bond exist
            1. alloy shrink faster
            2. ceramic will be "forced" to shrink more
         3. because ceramic are strong in compression
            1. this will resist cracks
         4. if alloy has lower COTE
            1. will pull ceramic apart
            2. tension
            3. cracks
   2. Fabrication
      1. 1. casting & recontouring of alloy substructure
         1. alloy thickness less than 0.5mm
      2. 2. Degas of alloy in ceramic oven
         1. remove impurities from alloy surface
         2. promote oxide layer
      3. 3. apply opaquing ceramic
         1. applied as paste
         2. remove excess water by vibration/ blotting
         3. fire condensed opaque layer in oven
         4. sintering
            1. ceramic particles melt together at the edges
         5. hide/mask the colour of alloy
      4. 4. apply gingival & incisal ceramic
         1. apply gingival ceramic first
            1. more yellow, less translucent
         2. apply same manner as opaque ceramic
      5. 5. glaze layer
         1. thin, nearly transparent, low-fusing ceramic
         2. seals ceramic surface
            1. high luster
6. All Ceramic restorations
   1. all ceramic crowns & fixed partial dentures
      1. feldspatic ACC
         1. excellent esthetic
      2. newer ceramic
         1. use high strength core ceramic beneath traditional ceramic
         2. eg of core: zirconia-, alumina-, lithium-based ceramic
            1. opaque & not esthetic
            2. may be sintered, slip-cast,or heat pressed to their final shape
         3. CAD-CAM
            1. design & cut core material out of a block of high-strength ceramic
      3. formed on special dies
         1. heat resistant
         2. these "refractory dies" are duplicated from gypsum-based working dies
      4. cementation
         1. cements must have controllable shades/ opaquers
   2. ceramic veneers
      1. made from traditional/ newer ceramics
      2. very fragile before they are bonded to tooth
         1. but after bond
            1. quite durable and force taken to break them same as to break enamel
      3. fabricated on refractory dies
      4. surface that contacts tooth will be treated with strong acid in lab
         1. care must be taken
            1. not to break them/ contaminate the acid-treated surface
7. Repair of ceramic
   1. if # not extensive
      1. repair with composite resin in dry field
      2. treated with special silane agent
         1. to promote composite-ceramic bonding
   2. Repair of fractured ceramic is possible
      1. but often
         1. does not restore the strength & esthetic of the original one