Introduction to Dental Materials Dr. Alaa El-din El-Araby, Ph.D Nagaski university, Japan.

Introduction to Dental Introduction to Dental MaterialsMaterials

Dr. Alaa El-din El-Araby, Ph.DDr. Alaa El-din El-Araby, Ph.D

Nagaski university, Japan.Nagaski university, Japan.

Three basic classes of materialsThree basic classes of materials:: MetalsMetals PolymersPolymers CeramicsCeramics

MetalsMetals

At the atomic level , the atoms are bonded At the atomic level , the atoms are bonded together by metalic bond.together by metalic bond.

-metalic luster.-metalic luster.

-excellent electrical and thermal conductivity.-excellent electrical and thermal conductivity.

-ability to be shaped (malleability).-ability to be shaped (malleability).

-strength, hardness, and high density.-strength, hardness, and high density.

-Opaque-Opaque

MetalsMetals

What is alloy?What is alloy? Mixture of 2 or more metalsMixture of 2 or more metals

What is metal??What is metal?? Metals versus alloys in dentistry.Metals versus alloys in dentistry.

Types of metals in dentistry:Types of metals in dentistry: Noble (gold, pt, Pd, …..Noble (gold, pt, Pd, ….. Seminoble ( old term).gold is replaced with silverSeminoble ( old term).gold is replaced with silver Non-noble.Non-noble.

MetalsMetals

Preformed metals:Preformed metals: Cohesive goldCohesive gold AmalgamAmalgam Wrought wiresWrought wires

MetalsMetals

Casting metalsCasting metals

The restoration is fabricated outside the mouth The restoration is fabricated outside the mouth utilizing the lost wax technique.utilizing the lost wax technique.

POLYMERSPOLYMERS

They are widely used in dentistry.They are widely used in dentistry.

Polymers versus plastics???Polymers versus plastics???

Plastic is any material cabable to be shaped .Plastic is any material cabable to be shaped .

Ductile metals considered as plastic Ductile metals considered as plastic

Polymers:Polymers:

this term means many partsthis term means many parts

Polymerisation: process by which the monomer Polymerisation: process by which the monomer is converted into polymer.is converted into polymer.

PolymersPolymers

They are bonded by covalent bonding along the They are bonded by covalent bonding along the backbone, and ionic bonding .backbone, and ionic bonding .

Polymers are prepared in form of dough then Polymers are prepared in form of dough then shaped into desired shapes.shaped into desired shapes.

They harden by:They harden by:

-physical reaction,(cooling, or evapration). -physical reaction,(cooling, or evapration). Waxes, Waxes,

-chemical reaction, -chemical reaction,

TypesTypes Impression.Impression. Waxes.Waxes. Denture bases.Denture bases. TCRM.TCRM.

CeramicsCeramics

They are made of metallic oxides.They are made of metallic oxides. Porcelain. Produced by sinteringPorcelain. Produced by sintering Glass, produced by melting and fusion of the Glass, produced by melting and fusion of the

oxides.oxides.

ceramicsceramics

They are bonded by ionic bonds.They are bonded by ionic bonds. No free electron to conduct heat or electricity.No free electron to conduct heat or electricity.

Poor thermal conductorPoor thermal conductor Stable ,biocompatibleStable ,biocompatible Trasparent.Trasparent.شفافشفاف Traslucency, due to air bublesTraslucency, due to air bubles Three dimensional crystal structure.Three dimensional crystal structure. BrittleBrittle

Types of ceramicsTypes of ceramics PorcelainPorcelain GypsumGypsum InvestmentInvestment CementsCements