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Introduction to Dental Materials

Dr Nadeem Hafeez KhokharAssociate Professor

Head Basic Dental sciences

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1. By preventing disease

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3. Improving mastication efficiency

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2. Relieving pain

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Goal of dentistry

Enhancing speech

and Improving

appearance.

Disease: Caries

Ortho treatment

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Materials used for tooth replacement 

1. Animal teeth

2. Human teeth

3. Seashells

4. Ivory5. Bone

6. Implants1. Hydroxyapatite

2. Cobalt Chromium

3. Titanium The denture, fabricated in 1789 for George

Washington, is carved from hippopotamus tusk

and originally contained eight human teeth.

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Classification of material used in dentistry

Four possible classesof materials are usedin dentistry: i.e.

1. Metal,

2. Ceramics,3. Polymers &

4. Composites.

Despite theimprovement in

physical propertiesnone of the materialare permanent.

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Metals  (characteristics)

Oldest of 4 used in dentistry as dental materials. A metal is defined with certain characteristics like1. Thermal & electrical conductivity,2. Dductility (they can bend without breaking),3. Oopacity (do not transmit light) &

4. Lustre (they have a surface that strongly reflect light &appears bright & shiny)

Another characteristic of metal is  elements which tend todissolve in water or aqueous solution producing atoms withpositive charges.

80% of elements in periodic table are metals.

All metals are white actually grey except gold  (yellow), copper (red).

The only metal in liquid form is mercury

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Metals

Metal solidify with theiratoms in a very regularor crystallinearrangement often incubes.

The increasing strengthof metallic bond causesmetal to haveincreasing meltingtemperatures.

Mercury is used in

dentistry to mix withparticles of other metalssuch as silver, tin, &copper to formamalgam.

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Metal

Because of their increasingstrength, stability &transformation into different shapes. They are extensivelyused to produce/replace loss

tooth structures as crowns Inlay : When portion of teeth to

be replaced is within the cusps.This type of restoration is calledInlay.

Onlay : When portion of teeth tobe replaced involves one ormore cusp but entire crown.

Metal crown bridge

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Metal Uses

Most instrumentsand equipment used in dentistryare made up of metals especiallysteel (nocorrosion,economical,sterilizable & canbe sharpened).

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Ceramics

Ceramics are combination of the metallic andnon-metallic elements.

They are manufactured by fusing together

oxide powders (such as silicon, aluminum,calcium & magnesium) in oven at hightemperatures.

Glass, Concrete, fine crystals & gypsums are

all ceramics. Most coloring pigments agent used or

dentistry are ceramic oxides hence any colorcan be produced.

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Characteristics

Glass ceramics are usedextensively as fillers fordental composites. They

are also used in severaldental cements &temporary restorativematerials.

Porcelain a special typeof ceramics extensivelyused in dentistry &other industries.

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In dentistry the use of ceramics is limited due totheir low fracture resistance as compared tometals.

Recently materials with improved fractureresistance have been developed for inlays,onlays & full crown restorations.

Because of their excellent biological properties,

ceramics are also used extensively as implant materials, either alone or as a coating for metalsubstructures made from titanium placed directlyinto maxilla or mandible.

Ceramics uses

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Implant 

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Widely used in the market as vinyl (nylon)polymers, gelatin (natural), cellulose, DNA

protein, rubber, silicon. These are giant long chain (carbon) organic

molecules.

Covalent bond within each molecule havingtremendous strength in one direction, e.g.breaking of nylon thread by pulling (elasticity).

Poor conductor of electricity & heat.

Polymers

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Uses

Silicon polymer made fromsilicon-oxygen bonds is usedas an impression materials.

Polymers are only used tomake teeth & denture basefor edentulous patients.

Temporary restorativematerial for onlay / inlay,temporary crown.

Used as adhesive agents toenhance bonding, sealant of 

pits & fissures.

Denture base polymer 

Silicon rubber impression

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Composite

Composites are mixture of two or more of first three classes in which different components remain distinct from one

another in the final structure. e.g. fiberglass, polymer reinforced with fine glassfibers.

They remains physically separate &uniformly distributed throughout thepolymer matrix.

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Historical background

Dentistry as a specialty is believed to have begunabout 3000B.C.

Phoenicians (2500 B.C) and Etruscans (after 800B.C)used gold bands and wires as partial dentures

Modern dentistry began in 1728, when Pierre

Fauchard (father of dentistry) published a treatisedescribing many types of dental restorationsincluding artificial denture with ivory

In 1756 Pfaff described a method of takingimpression in mouth with wax and making a modelwith plaster of Paris.

De Chamant in 1792 patented a process for theconstruction of porcelain teeth.

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Historical background

In 1895 G V Black (pioneer of restorativedentistry) brought dentistry to its peak.

In 1919 the National Bureau of Standards(now NIST National Institute of Standards

and Technology) set up evaluation andselection of dental amalgam for use in federalservice.

In 1928 the Dental Research Fellowship at NBS was assumed by ADA. It was the

enthusiasm of the member of this team that first course in dental material was inducted inDental schools.

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American Dental Association

Measurement of physical and chemical properties of dental material that are of clinical significance.

Developments of new material, instruments and test methods

It issues seal of approval to instruments andmaterials fit for use in dentistry.

The ASC (Accredited Standard Committee) MD156develops specifications for all dental products except X-ray films and drugs.

FDA (food and drug administration) protects thepublic from hazardous or ineffective medical anddental devices like x-rays and drugs.

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International Standards

FDI (Fdration Dentaire Internationale) andISO (International Standard Organization) areworking toward standardization of dentalmaterials and devices.

ISO is composed of standard organizationsfrom more than 80 countries.

The responsibility of this organization is tostandardize terminology and test methods

and to determine specifications for dentalmaterials , instruments, appliances andequipments.