Fabrication of Dental Ceramic Crown
Dental ceramic crown is also known as all ceramics used for aesthetic purposes. These all ceramic restorations are routinely used in dentistry. They are made up of translucent porcelain, reflecting light and look almost exactly like natural teeth. Based on fabrication metal free ceramic are classified as;
1. Conventional (powder slurry ceramics)
2. Castable ceramics
3. Machinable
4. Pressable
5. Infiltrated
Conventional Ceramic Crown
They are powdered products to which water is added to produce slurry. Slurry is built up in layers on a due to form the contours of restoration. The powder itself is available in different shades and translucencies. These products are available in powder form to which water is added by the technician to produce slurry. In order to form the contours of the restoration, slurry is built up in layers on a die. The powders supplied with characterizing stains and glazes are available in different shades and translucencies.
Castable
These ceramics are used for fabrication of cores or full contour restorations using a lost wax and centrifugal casting technique. Castable ceramics are supplied as solid ceramic blocks like bricks and are available in single shade. They are covered by conventional feldspathic porcelain or stained in order to achieve proper shading of final restorations. These products are supplied as solid ceramic ingots, which are used for fabrication of cores or full-contour restorations using a lostwax and centrifugal casting technique. The material is generally available in single shade which is either covered by conventional feldspathic porcelain or stained for achieving proper shading and characterization of the final restoration.
Machinable
They are available in the form of ceramic ingots (blocks) which are used in CAD CAM procedures. The machines restorations are then stained and glazed to obtain the desired results. CAD CAM technique uses the digital information of the tooth preparation. Computer aided design is then created on a video monitor. The image acts as a reference for designing the restoration on video monitor. After accepting a 3D image for the restoration design the computer translates this image into a set of instructions to guide the milking machine in cutting the restoration from the ceramic block. These products are supplied as ceramic ingots in various shades and are used in computer aided design – computer aided manufacturing, or CAD-CAM, procedures. The machined restoration can be stained and glazed to obtain the desired characterization.
Pressable
These products are also available in the form of ceramic ingots . They are melted at higher temperatures and pressed into a mound created using lost wax technique. The presses form can then be made to full contour restoration or can be used for porcelain build up. Also supplied as ceramic ingots, these products are melted at high temperatures and pressed into a mold created using the lost-wax technique. The pressed form can be made to full contour, or can be used as a substrate for conventional feldspathic porcelain buildup.
Infiltrated ceramic
These products are supplied as two components: a powder (aluminum oxide or spinel) fabricated into a porous substrate and a glass infiltrated into the porous substrate at high temperature. The infiltrated ceramic will then be veneered while using conventional feldspathic porcelain technique.
These ceramics are available in two components :
A. A powder consisting of aluminum oxide fabricated into a porous substrate
B. A glass infiltrated into a porous substrate at high temperatures.
The infiltrated ceramic will then be veneered while using conventional feldspathic porcelain technique. Fabrication procedure should be done in a manner that when prosthesis is fabricated it gives high strength, durability, biocompatibility, translucency and best gingival marginal fit for prolonged esthetics.
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