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Introduction to Dental Materials. Three basic classes of materials : Metals Polymers Ceramics. Metals. At the atomic level , the atoms are bonded together by metallic bond. -metallic luster. -excellent electrical and thermal conductivity. -ability to be shaped (malleability).
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Three basic classes of materials: • Metals • Polymers • Ceramics
Metals At the atomic level , the atoms are bonded together by metallic bond. -metallic luster. -excellent electrical and thermal conductivity. -ability to be shaped (malleability). -strength, hardness, and high density. -Opaque
Metals • What is alloy? • Mixture of 2 or more metals • What is metal?? • Metals versus alloys in dentistry.
Types of metals in dentistry: • Noble (gold, pt, Pd, ….. • Semi-noble ( old term).gold is replaced with silver • Non-noble.
Metals • Preformed metals: • Cohesive gold • Amalgam • Wrought wires
Metals • Casting metals The restoration is fabricated outside the mouth utilizing the lost wax technique.
POLYMERS • They are widely used in dentistry. Polymers versus plastics??? Plastic is any material cabable to be shaped . Ductile metals considered as plastic
Polymers: this term means many parts Polymerisation: process by which the monomer is converted into polymer.
Polymers They are bonded by covalent bonding along the backbone, and ionic bonding . Polymers are prepared in form of dough then shaped into desired shapes. They harden by: -physical reaction,(cooling, or evapration). Waxes, -chemical reaction,
Types • Impression. • Waxes. • Denture bases. • TCRM.
Ceramics • They are made of metallic oxides. • Porcelain. Produced by sintering • Glass, produced by melting and fusion of the oxides.
ceramics • They are bonded by ionic bonds. • No free electron to conduct heat or electricity. • Poor thermal conductor • Stable ,biocompatible • Trasparent.شفاف • Traslucency, due to air bubles • Three dimensional crystal structure. • Brittle
Types of ceramics • Porcelain • Gypsum • Investment • Cements