Metal alloys DR.LINDA MAHER

Types of casting metal alloys 1-high nobel alloys 2-nobel alloys . Definition Nobel metals Base metals Metal alloys used as Types of casting metal alloys 1-high nobel alloys 2-nobel alloys 3-base metal alloys Wrought alloys biocompatibility

Metals have been used in dentistry for thousands of years as a replacement for missing tooth structures Metals and non metals are mixed together to form alloys with better physical properties

METAL ALLOYS Metal alloys: a mixture of two or more metals In dentistry, metal alloys are always used and no single metal is used alone.

TYPES OF METALS: 1-noble metals 2-base metals

Noble METALS #Noble metals are those with good and retained metallic luster in dry air. #Their resistance to corrosion in moist air is excellent #Gold (Au),silver (Ag) Platinum (Pt) and Palladium (Pb)

BASE METALS refers to a metal that oxides or corrodes relatively easily Base metals are required in alloys for the strength and flexibility properties Copper (Cu), Zinc (Zn), , Nickel (Ni), Titanium (Ti)

TYPES OF METAL ALLOYS 1\High Noble alloys 2\Noble alloys 3\Base metal alloys

1\High Noble alloys At least 60% of Nobel metals( gold, palladium or platinum) and At least 40% gold Properties: 1\These alloys are the most expensive 2\They are easy to manipulate in the laboratory 3\Very low corrosion properties in the mouth

2\ Noble alloys Properties: At least 25% of noble metal content Not necessarily containing gold They could be: Gold-based ,Palladium or Silver-based Properties: 1\Corrosion in the mouth is low 2\ strengths and hardness are equal to or greater than High-noble alloys 3\These alloys are expensive

3\BASE METAL ALLOYS Primarily contain nickel, cobalt, or titanium May contain minor amounts of noble metals Properties: 1\Extremely high strengths and hardness (The most difficult to manipulate in the laboratory) 2\High corrosion 3\Low cost

Uses of base metal: 3-implant 1-Removable partial denture and full denture base 2-Crown and bridge 3-implant

Wrought alloys Alloys that are shaped into another form by mechanical force

Uses of wrought alloy 1\Orthodontic wires (Ti, Ni-Ti or stainless steel) 2\Endodontic files (Ni-Ti or stainless steel) 3\removable partial denture clasps

BIOCOMPATIBILITY Biocompatibility is related primarily to their corrosion Corrosion releases more of its elements into the mouth increasing the risk for unwanted reactions (Unpleasant tastes, irritation, allergy and others) THE MORE CORROSIVE THE METAL ,THE LEAST BIOCOMPATIBLE

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