All-Ceramic System

What is All-Ceramic System ? 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.

Advantages of All-Ceramic 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

Objective of this seminar 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

Various all ceramic systemsAluminous core ceramicsSlip cast ceramicsHeat pressed ceramicsMachined ceramicsMachined and sintered ceramicsMetal reinforced system

Aluminous core ceramicsIntroduced by Mc Lean and HughesThey advocated using aluminous porcelain, which is composed of aluminium oxide crystals dispersed in a glassy matrixIt contains an opaque inner core containing 50% by weight alumina for high strengthCore is veneered by a combination of esthetic body and enamel porcelain with 15% and 5% crystalline alumina respectively40% stronger than traditional feldspathic porcelain

Slip cast ceramicsIn ceramIt is a traditional techniqueStarting medium is slip that is an aqueous suspension of fine ceramic particles in water with a dispersing agentThe 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 firingThe 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 ceramicsHeat pressing improves the marginal adaptation - Leucite based -Lithium silicate basedLeucite 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 techniqueCurrently 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 machinableCerec 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 ceramicsExtensive research in the field of Zirconia ceramics and CAD/CAM technology has led to the development of Zirconia ceramics for dental restorationThe 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 shrinkageThe restorations are later sintered at a high temperatureTwo 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

1. Pressable Ceramic Restorations

1. Pressable Ceramic Restorations

1. Pressable Ceramic Restorations

2. Stacked Feldspathic Restorations

1. CAD/CAM Technique

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