RECENT ADVANCES IN DENTAL CERAMICS. CONTENTS. Introduction History Glass infiltrated alumina Incerams Procera all ceram Pressable ceramics Machinable ceramics CAD CAM. INTRODUCTION.
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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 • resin-bonded ceramics • metal-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 ABRASIVENESS • ANT. • POST. • CROWNS • VENEERS • P&C COMPOSITION PROCESSING METHOD TRANSLUCENCY • PURE ALUMINA • P.ZIRCONIA • P.SILICA GLASS • LEUCITE.G.CER • LITHIA BASED FIRING TEMP. MICRO STRUCTURE • SINTERING • PARTIAL SINT • GLASS INFIL. • CAD-CAM • COPY MILLING • OPAQUE • TRANSLUCENT • TRANSPARENT • LOW FUSING • MEDIUM • HIGH FUSING • GLASS • CRYTALLINE • CRYSTAL -GLASS
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. One solution is to provide the dental porcelain with support from a stronger substructure. 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
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.
No metal component Translucent ceramic core Moderately high flexural strength Excellent fit Excellent esthetics ADVANTAGES
Disadvantages Potential to fracture(in posterior) Requires a resin cement to micromechanically bond to the tooth structure.
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