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Cast base-metal alloys are rarely used to make full metal crowns. They are more commonly used as part of metal-ceramic crowns as bonding alloys. When compared to high-noble and noble alloys, they are stronger and harder; they can be used in thinner sections (0.3mm as opposed to 0.5mm) however they are harder to adjust and are more likely to ...
Extracoronal preparations provide a core or base upon which restorative material will be placed to bring the tooth back into a functional and aesthetic structure. Examples include crowns and onlays, as well as veneers. In preparing a tooth for a restoration, a number of considerations will determine the type and extent of the preparation.
To fabricate an amalgam filling, the dentist uses a mixing device to blend roughly equal parts (by mass) of shavings of a silver-base alloy with mercury until the shavings are thoroughly wetted. The silver alloy is typically 40–70% Ag, 25-29% Sn, 2–40% Cu and 0–2% Zn (when the alloy is formulated Zn is a scavenger and is mostly consumed ...
Water-based acid-base cements: zinc phosphate (Zn 3 (PO 4) 2), zinc polyacrylate (polycarboxylate), glass ionomer (GIC). These contain metal oxide or silicate fillers embedded in a salt matrix. Non-aqueous/oil base acid-base cements: zinc oxide eugenol and non-eugenol zinc oxide. These contain metal oxide fillers embedded in a metal salt matrix.
Minimize filler metal/base metal interaction; Maximize the life of any fixtures or jigs used [6] In some cases, a worker may select a higher temperature to accommodate other factors in the design (e.g., to allow use of a different filler metal, or to control metallurgical effects, or to sufficiently remove surface contamination).
Normally not used for copper or silver-based alloys; flow point close to melting point of silver, and too readily alloys with copper. Low penetration of base metal, suitable for brazing thin parts, e.g. thin-wall tubing or vacuum tubes. Does not produce severe intergranular penetrations characteristic for boron-containing nickel brazing alloys.
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As conservation of tooth structure is a key ingredient in tooth preservation, many dentists prefer placing materials like composite instead of amalgam fillings whenever possible. Generally, composite fillings are used to fill a carious lesion involving highly visible areas (such as the central incisors or any other teeth that can be seen when ...