Download Introduction to Dental Materials

Introduction to Dental
Materials
Dr. Alaa El-din El-Araby, Ph.D
Nagaski university, Japan.
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Three basic classes of materials:
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Metals
Polymers
Ceramics
Metals
At the atomic level , the atoms are bonded
together by metalic bond.
-metalic luster.
-excellent electrical and thermal conductivity.
-ability to be shaped (malleability).
-strength, hardness, and high density.
-Opaque
Metals
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What is alloy?
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Mixture of 2 or more metals
What is metal??
Metals versus alloys in dentistry.
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Types of metals in dentistry:
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Noble (gold, pt, Pd, …..
Seminoble ( old term).gold is replaced with silver
Non-noble.
Metals
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Preformed metals:
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Cohesive gold
Amalgam
Wrought wires
Metals
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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
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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,
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Types
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Impression.
Waxes.
Denture bases.
TCRM.
Ceramics
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They are made of metallic oxides.
Porcelain. Produced by sintering
Glass, produced by melting and fusion of the
oxides.
ceramics
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They are bonded by ionic bonds.
No free electron to conduct heat or electricity.
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Poor thermal conductor
Stable ,biocompatible
Trasparent.‫شفاف‬
Traslucency, due to air bubles
Three dimensional crystal structure.
Brittle
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Types of ceramics
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Porcelain
Gypsum
Investment
Cements