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RECENT ADVANCES IN DENTAL CERAMICS

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RECENT   ADVANCES IN           DENTAL CERAMICS Powered By Docstoc
					    RECENT
  ADVANCES IN
DENTAL CERAMICS
               CONTENTS
•   Introduction
•   History
•   Glass infiltrated alumina
•   Incerams
•   Procera all ceram
•   Pressable ceramics
•   Machinable ceramics
•   CAD CAM
          INTRODUCTION

Though conventional ceramics provide
esthetically pleasing retorations they have many
drawbacks which limit their use.With more and
more studies coming in the field of ceramics and
with the advent of digital technology newer and
better products are flooding the market these
days.The “chinese clay” of olden days have
become the unavoidable product in esthetic
dentistry...
                 •* reinforced ceramic core systems
•
•




    • metal-ceramics                   •resin-bonded
                                       ceramics
                  HISTORY
   Since the stone age ceramics have been
    important for humans.

   1789-de_chemant & Duchateau.
   1822-baking process.
   1825-commercial production by Stockton.
   1903-Dr.Charles Land-first ceramic crown
   1962-Patents by weinstien and wenstein.
   1965-Mclean & Hughes
                 CLASSIFICATION

                                                            USE
ABRASIVEN
ESS                                                      ANT.
        COMPO                                            POST.
        SITION                                           CROWNS
                  PROCESSING                             VENEERS
                                               TRANSLU   P&C
                  METHOD
PURE ALUMINA                                  CENCY
                          FIRING TEMP.     MICRO
P.ZIRCONIA     SINTERING                 STRUCT  OPAQUE
                              LOW FUSING URE       TRANSLUCENT
P.SILICA GLASS PARTIAL SINT                       TRANSPARENT
                              MEDIUM       GLASS
LEUCITE.G.CER GLASS INFIL.
                              HIGH FUSING  CRYTALLINE
LITHIA BASED CAD-CAM
                                            CRYSTAL -GLASS
                COPY MILLING
WHY DO WE NEED ADVANCED
      PRODUCTS ???
• One of the most serious drawbacks with the early dental
  porcelains were their lack of strength and toughness, which
  seriously limited their use. In order to overcome these
  problems, there are two possible solution.
1. One solution is to provide the dental porcelain with
   support from a stronger substructure.
2. The other option is to produce ceramics, which are stronger
   and tougher.
       Metal free ceramic systems
   All ceramic systems can provide better esthetics.
   Wide range of tranlucency opacities are available
   Soft tissue health
   No over contouring
        Glass infiltrated alumina
   In-ceram alumina
   Supplied as one of the three core ceramics.
   1)in-ceram spinell
   2)in-ceram alumina
   3)in-ceram zirconia
                   In - ceram
   A slurry of material is slip cast on porous
    refractory die and heated in a furnace to produce
    a partially sineterd coping.
   This coping is infiltrated with glass at
    temp1100*c -4hrs
             In-ceram alumina
   Indication-anterior and posterior crowns and
    anterior 3-unit FPDs.
   Flexuarl strength-500mPa
   The final ICA core consists of 70wt% alumina
    and 30wt%sodiumlnathanum glass.
                  Advantages
   Moderately high flexural strength and fracture
    resistance.
   A metal free structure
   An ability to be used succesfully with
    conventional luting cements
                   Drawbacks
   Marginal seal is not as good as procera-all ceram
    or IPS Empress.
   High degree of opacity
   Inability to be etched
   Technique sensitive
              In ceram spinnel
   Indications-anterior single unit
    creowna,inlays,onlays & veneers.
   It is the most translucent among the three .
   It was introduced as an aletrnative to ICA
Improved translucency.....better esthetics.
            single    anterior    single    posterior   Inlays   onlays   veneers
           anterior   bridges    posterio    bridges
               s                    rs


  In-         X                                           X        X        X
Ceram
Spinell




  In-         X          X          X
 Ceram
Alumina




   In-                              X          X
 Ceram
Zirconia
             In ceram zirconia

Indication-posterior crowns
Not recommended in anteriors due to the high
degree of opacity
But has good modulous of elasticity and fracture
toghness.
Though it has better strength its use is limited to
posteriors due to its greater opacity.
   Castable and machinable
           ceramics


When used in posteriors ceramic crowns are
         succeptible to fracture.
             Critical flaw...??
 First commercially available castable ceramic-
dicor,developed by corning glass works.
 Dicor is a castable glass.
 Indicated for onlays,facial veneers,full crown
restorations.
 technique......ceramming
             Procera all ceram

Composed of densely sintered high purity
Aluminium oxide core+all ceram veneering
porcelain.
Contains 99% alumina.
It is one of the hardest among the ceramics.
Indications-anterior & posterior
crowns,veneers,onlays...
Procera scanner is used.
It is developed through CAD-CAM processing.
          CAD-CAM ceramics


Computer aided designing and computer aided
milling.
The internal surface of inlays or crowns is ground
with diamond discs according to the scanned image
of the praparation
             ADVANTAGES


No  wear of the opposing tooth
Strength

Fracture resistance

Low translucensy
               Lava zirconia
They are zirconia based products.
First the milled prosthesis is removed from the
  milling unit.
The zirconia frame work is placed in the cercon
  furnace and fire at 1350*C for 6 hours.
 The purest tetragonal zirconia has got the greatest
fracture toughness and flexural strength.
 Contra indicated in patients with bruxism.
 Only minimal occlusal reduction of 2mm needed.
           Finesse all ceramic


It is a new product patended to dentsply.
      Indications-crowns anterior&posterior
                  Veneers
                  Inlays
                  onlays
• Finesse All-Ceramic achieve an ideal bond
  without the need to create a wash layer
• Thus saving time and enhancing the strength of
  the restoration.
• It is a leucite reinforced ceramic glass material.
• Flexural strength- 125mPa
•   "Pressing" - lost wax injection molding
•   At 930°C, for 20 min
•   Inherently fluorescent
•   Ideal transparency range from (clear) to
    (opaceous)
PRESSABLE CERAMICS

Introduces by MAC CULLOCH IN 1968
Here,the glass is formed into the devised
shape.
Then it is subjected to partial devitrification.a
presssure moulding technique is followed.
• IPS empress-is a glass ceramic avialable as
  ingots,
• Which can be heated and pressed until the
  ingots flows into a mold.
• It contains higher concentration of leucite
  crystals that increase the resistance to crack
  propagation.
• It can be tained ,glazed or built up by layering
  technique.
            ADVANTAGES
No metal component
• Translucent ceramic core
• Moderately high flexural strength
• Excellent fit
• Excellent esthetics
         Disadvantages
Potential to fracture(in posterior)
Requires a resin cement to micromechanically
bond to the tooth structure.
Y - TZP...??
    Yttrium tetragonal zirconia
            polycrystal
•   One the latest advacements in the field of all
    ceramic restorations.
•   Phase transformation from monoclonal to
    tetragonal on firing.
•   Adding zerconia stablizes the core during this
    phase transformation.
• Also the presence of water causes crack
  propagation and stress corrosion reactions.
• But Y-TZP substructures are independent of
  this phenomena.
• In vitro studies show a flexural strength of 900-
  1200mPa.
    Hydroxy apatite based ceramics
•    Cera pearl,developed by Kyocera co. in CA.
•    Here the main ceystalline phase is oxy apatite which
     can be tranformed to hydroxy apatite on hydration.
•    Commonly used in implants...for better flexural
     strength and bonding.
                     Shade
•     Dimensions of color
         Hue

         Chroma

         Value




    Metamerism &
    Flouresence
                Conclusion
•   Advances in the field of ceramics gives hand
    full of newer products for the dentist.
•   Which will surely enhance the esthetic and
    strength characters.
•   A carefull selection of these products are
    essential for successful outcome.
               Bibliography
•   Text book of dental materials-Anusavice.
•   Dental technitian news letter-2009 march
•   Text book of ceramics fabrication-Naylor.
•   Recent advances in ceramics-
    Dr.Jennifer,ohio,USA
THANK YOU

				
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posted:5/11/2012
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