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All-Ceramic System dr shabeel p n
All Ceramic system is the foundation cap that supports final dental crown. A dental restorative material used artificially to restore the function, integrity and morphology of missing tooth structure. The structural loss typically results from caries or external trauma. It is also lost intentionally during tooth preparation to improve the aesthetics or the physical integrity of the intended restorative material. Dental restoration also refers to the replacement of missing tooth structure by restoring dental implants. What is All-Ceramic System ?
The secret behind All Ceramic is its unique combination of strength and beauty All Ceramic is a coping made extremely densely-sintered aluminum oxide All Ceramic can be recommended for prosthetic reconstructions anywhere in your mouth All Ceramic is made of a bio-compatible material (comparable to Titanium) which minimizes the risk of allergic reactions All Ceramic Porcelain opens an entirely new era in history using porcelain in dentistry Advantages of All-Ceramic
Discern between the different methods of fabrication of porcelain veneers Discuss the advantages and disadvantages of various techniques for fabricating porcelain veneers Explain which clinical indications would be most appropriate for each type of porcelain restoration Objective of this seminar
Various all ceramic systems • Aluminous core ceramics • Slip cast ceramics • Heat pressed ceramics • Machined ceramics • Machined and sintered ceramics • Metal reinforced system
Aluminous core ceramics • Introduced by Mc Lean and Hughes • They advocated using aluminous porcelain, which is composed of aluminium oxide crystals dispersed in a glassy matrix • It contains an opaque inner core containing 50% by weight alumina for high strength • Core is veneered by a combination of esthetic body and enamel porcelain with 15% and 5% crystalline alumina respectively • 40% stronger than traditional feldspathic porcelain
Slip cast ceramics • In ceram • It is a traditional technique • Starting medium is slip that is an aqueous suspension of fine ceramic particles in water with a dispersing agent • The slip is applied on to a porous refractory die which absorbs water from the slip and leads to condensation of slip on the die
The die is then fired at high temperature(1150 degree Celsius) • The die shrinks more than the condensed slip which allows easy separation after firing • The fired porous core is then glass infiltrated Advantages: -Lower porosity -Fewer processing defect -Better strength
Two modified porcelain composition for in ceram technique have been introduced 1, In ceram spinell- contain Magnesium spinel- improved translucency 2, In ceram Zirconia – Zirconium oxide -better strength
Heat pressed ceramics • Heat pressing improves the marginal adaptation - Leucite based -Lithium silicate based • Leucite based -contain leucite as a major reinforcing crystalline phase dispersed in a glassy matrix -ceramic ingots are pressed at a higher temperature (1165 degree Celsius ) into a refractory mold made by lost wax technique
Two finishing techniques can be used for application of veneering porcelain 1 characterization technique (surface stain only) 2 layering technique • Currently available leucite containing materials -IPS Empress -Optimal pressable ceramic -Cerpress Lower fusing material -Finesse
Lithium silicate based eg – IPS Empress-2 -The major crystalline phase of the core material is Lithium disilicate -The material is pressed at 920 degree Celsius and layered with a glass containing some dispersed apatite crystals
Machined ceramics • The evolution of computer aided design / computer assisted machining [CAD/CAM] systems led to the development of new generation ceramics that are machinable • Cerec system: -The equipment consists of a computer integrated imaging and milling system,with the restorations designed on the computer screen -Tooth preparation follows typical all ceramic guidelines
-Coat the preparation with opaque powder -Image the preparation with the optical scanner -Identify and mark the margins and contour on the computer screen -Insert the appropriate shade of ceramic block in the milling machine. The fabrication time for a crown is about 20 minutes -Try the restoration back in the mouth
Machined and sintered ceramics • Extensive research in the field of Zirconia ceramics and CAD/CAM technology has led to the development of Zirconia ceramics for dental restoration • The material used is tetragonal Zirconia stabilized with 3 mole percent yttrium oxide
Enlarged Zirconia copings are machined from pre -sintered Zirconia blocks to compensate for the sintering shrinkage • The restorations are later sintered at a high temperature • Two systems: -Procera All ceram system -Lava system
Practical Example of All-Ceramic restoration A conservative All-Ceramic restoration was used to restore the tooth without pasting a post and core and devitalizing the tooth A facial veneer that placed on tooth no 9 instead of full coverage restoration. No post and core was necessary in this case.
Practical Example of All-Ceramic restoration Using opaque layer of porcelain
