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Restorative Composite ResinsRestorative Composite Resins

Dr Dr AmalAmal EzzEzz El Din El Din FahmyFahmy

AssisAssis Prof. Dental Biomaterials Department Prof. Dental Biomaterials Department Faculty of Dentistry Alexandria UniversityFaculty of Dentistry Alexandria University

Objectives• Historical back ground

• Ideal requirements of restorative materials

•• Indications, contraindications and Uses of Indications, contraindications and Uses of

Composites [ applications] Composites [ applications]

•• CompositionComposition

•• Classification based on the fillers particle Classification based on the fillers particle

size size

•• Classification based on the mode of curingClassification based on the mode of curing

•• Light curing units Light curing units

•• Properties of composites Properties of composites

•• Acid etch techniqueAcid etch technique

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IDEAL REQUIREMENTS OF RESTORAIVE IDEAL REQUIREMENTS OF RESTORAIVE

MATERIALSMATERIALS

••ExcellentExcellent physicalphysical andand mechanicalmechanical propertiesproperties

••HighHigh glossgloss ,polish,polish abilityability ,color,color stabilitystability

••BiocompatibilityBiocompatibility toto pulp,pulp, gingivalgingival tissuestissues

••RadioRadio opacityopacity

••GoodGood adhesionadhesion toto enamelenamel andand dentinedentine

••MinimalMinimal dimensionaldimensional changeschanges uponupon settingsetting

••GoodGood abrasionabrasion &fracture&fracture resistanceresistance

••NoNo mismatchmismatch inin CoefficientCoefficient ofof thermalthermalexpansionexpansion betweenbetween thethe fillingfilling andand toothtooth ..

••NoNo waterwater sorptionsorption oror solubilitysolubility

Restorative Materials for Anterior teeth

1. Silicate cements (not used anymore)

2. Glass Ionomer Cements

3. Polymeric Restorative Materials

a) Type I (Acrylic Unfilled Resin):

b) Type II (Composite Resin, Filled Resin)

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History

• 1871 – silicates

– alumina-silica glass & phosphoric acid

– very soluble

– poor mechanical properties

• 1948 - acrylic resins

– polymethylmethacrylate

– high polymerization shrinkage

Rueggeberg J Prosthet Dent Rueggeberg J Prosthet Dent 20022002

• Disadvantages:

– Monomer penetrates DT

causing pulpal irritation.

– Poor mechanical

properties

– Staining

– Higher TEC than tooth

causing Marginal

Percolation Phenomenon

– High polymerization

shrinkage causing

marginal gap,

Microleakage and

recurrent caries..

POWDER

PMMA + INITIATOR (BENZOYL

PEROXIDE)

LIQUID

MMA + ACTIVATOR (TERTIARY

AMINE)

N.B: NO FILLERS

UNFILLED SELF CURING ACRYLIC RESINSUNFILLED SELF CURING ACRYLIC RESINS

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MICROLEAKAGE PROBLEMSMICROLEAKAGE PROBLEMS

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History(cont.)

• 1962 – Bis-GMA

– stronger resin

• 1969 – filled composite resin

– improved mechanical properties

– less shrinkage

– paste/paste system

• 1970’s – acid etching and microfills

• 1980’s – light curing and hybrids

• 1990’s – flowables and packables

• 2000’s – nanofills Rueggeberg J Prosthet Dent Rueggeberg J Prosthet Dent 20022002

Indications Indications

Contraindications Contraindications

and Uses of and Uses of

Composite ResinsComposite Resins

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Indications

• Anterior restorations

• Posterior restorations

– preventive resin

– conservative class 1 or 2

Contraindications

• Large posterior

restorations

• Bruxism

• Poor isolation

• Patients with bad oral

hygiene (composite not anticariostatic)

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BLACK’S CLASSIFICATIONS OF CAVITY BLACK’S CLASSIFICATIONS OF CAVITY PREPARATIONSPREPARATIONS

Class I Class I

Class II Class II

Class IV Class IV Class III Class III Class V Class V

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Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites

Class IIIClass III

Peg lateralPeg lateral

Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites

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Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites

Diastema closureDiastema closureDiastema closureDiastema closureDiastema closureDiastema closureDiastema closureDiastema closure

Veneers Veneers Veneers Veneers Veneers Veneers Veneers Veneers

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Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites

Bonding of orthodontic brackets and bandsBonding of orthodontic brackets and bandsBonding of orthodontic brackets and bandsBonding of orthodontic brackets and bandsBonding of orthodontic brackets and bandsBonding of orthodontic brackets and bandsBonding of orthodontic brackets and bandsBonding of orthodontic brackets and bands

Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites Uses of Composites

Fissure Fissure Fissure Fissure Fissure Fissure Fissure Fissure

sealant sealant sealant sealant sealant sealant sealant sealant

Core Core Core Core Core Core Core Core

buildupbuildupbuildupbuildupbuildupbuildupbuildupbuildup

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5/16/201221

Sealants 22. Apply sealant. Apply sealant

11. Etch enamel. Etch enamel

Courtesy of Courtesy of 33M DentalM Dental

ProductsProducts

33. Light cure. Light cure

Composite Restorative ResinsComposite Restorative ResinsComposite Restorative ResinsComposite Restorative ResinsComposite Restorative ResinsComposite Restorative ResinsComposite Restorative ResinsComposite Restorative Resins

••ByBy definition,definition, aa compositecomposite isis aa combinationcombination

ofof twotwo chemicallychemically differentdifferent materialsmaterials withwith aa

distinctdistinct interfaceinterface betweenbetween them,them, andand havinghaving

propertiesproperties whichwhich couldcould notnot bebe achievedachieved byby

anyany ofof thethe componentscomponents alonealone..

••DentalDental compositescomposites areare highlyhighly crosscross--linkedlinked

polymericpolymeric materialsmaterials reinforcedreinforced byby aa

dispersiondispersion ofof glass,glass, crystalline,crystalline, oror resinresin fillerfiller

particlesparticles and/orand/or shortshort fibersfibers boundbound toto thethe

matrixmatrix byby silanesilane couplingcoupling agentsagents..

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COMPOSITE RESINSCOMPOSITE RESINSCOMPOSITE RESINSCOMPOSITE RESINSCOMPOSITE RESINSCOMPOSITE RESINSCOMPOSITE RESINSCOMPOSITE RESINS

•• DevelopedDeveloped 19601960ss composedcomposed ofof twotwo oror

moremore distinctdistinct phasesphases

•• CombinationCombination ofof inorganicinorganic fillerfiller particlesparticles

bondedbonded toto aa softsoft dimethacrylatedimethacrylate polymerpolymer

•• AdvantagesAdvantages:: improvedimproved mechanicalmechanical

propertiesproperties –– easyeasy toto useuse –– estheticsesthetics

•• UsedUsed inin classclass IIIIII,, IVIV andand VV asas wellwell asas aa inin

conservativeconservative posteriorposterior restorationrestoration

Composition of Composition of

composite resinscomposite resins

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CompositionCompositionCompositionCompositionCompositionCompositionCompositionComposition

•• OrganicOrganic polymerpolymer phasephase (resin(resinmatrix)matrix)

•• InorganicInorganic phasephase (dispersed(dispersed phase/phase/fillers)fillers)

•• InterfacialInterfacial phasephase (coupling(coupling agent)agent)

•• InitiatorsInitiators andand activatorsactivators

•• PigmentsPigments

•• InhibitorsInhibitors

Filled Composite Resin:

Composition

Resin Matrix

(Organic Phase)

Bis-GMA

(Bowen’s resin)

UDMA

TEGDMA

DEGDMA

Fillers

(Inorganic Phase)

Silica(quartz)

Glass Fibers

Lithium

Barium

Strontium

Coupling agent

(Interfacial Phase)

Silane

Gamma methacryloxypropyl silane

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Organic Polymer Organic Polymer

PhasePhase

•• DifunctionalDifunctional dimethacrylatedimethacrylate monomermonomer

•• BISBIS--GMAGMA oror UDMAUDMA

•• DiluentsDiluents asas DEGDMADEGDMA oror TEGDMATEGDMA

•• 7575%% BISGMABISGMA ++ 2525%% DiluentDiluent

•• FunctionFunction ofof organicorganic matrixmatrix::

––ProtectProtect thethe disperseddispersed phasephase toto retainretain it’sit’s

strengthstrength

––CementCement thethe fillersfillers intointo bundlesbundles

––TransferTransfer externallyexternally appliedapplied loadload toto thethe fillersfillers

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Organic polymer phase

•Bis-GMA : extremely viscous

large benzene rings

lowered by adding TEGDMA

freely movable

increases polymer conversion

increases cross linking

increases in diluents increase shrinkage

CHCH22=C=C--CC--OO--CHCH22CHCH--CHCH22OO --CC-- OCHOCH22CHCHCHCH22OO--CC--C=CHC=CH22

CHCH33 CHCH33

CHCH33

CHCH33OHOH OHOH

OO OO

5/16/201230

Most common dental resins

triethylenetriethylene glycol glycol dimethacrylatedimethacrylate

BisphenolBisphenol A A glycidylglycidyl dimethacrylatedimethacrylate

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••Lower polymerization Lower polymerization

shrinkageshrinkage

Lower coefficient of Lower coefficient of

thermal expansionthermal expansion

Harder and stronger Harder and stronger

cross linked polymercross linked polymer

Less water sorption Less water sorption

UDMA IS LESS UDMA IS LESS

VISCOUSVISCOUS--LESS LESS

WATER SORPTIONWATER SORPTION

•• High viscosity which High viscosity which require thinning by require thinning by diluent monomersdiluent monomers

•• High water sorptionHigh water sorption

•• Air inhibition of Air inhibition of polymerizationpolymerization

Organic Polymer PhaseOrganic Polymer Phase

First increment 1.5

AIR

Second increment

Composition & Structure:Resin matrix

•Oligomers (2Monomers)–Monomer:Methylmethacrylate (MMA)

•Dimethacrylate(Bis-GMA)

•Urethane dimethacrylate(UDMA)

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Filled Composite Resin:

Composition

Role of each constituent

Resin Matrix

(Organic Phase)

1. Protect Fillers

2. Cushion transferring loads to

strong fibers

3. Hold fillers together

Responsible for:

Physical Properties

Fillers

(Inorganic Phase)

1. Strength

2. Hardness

3. Abrasion resistance

Responsible for:

Mechanical properties

Coupling agent

(Interfacial Phase)

Bond matrix to fillers

Responsible for:

Filler to matrix bond

Filled Composite Resin:

Composition (cont’d)

Initiators

Chemically Activated

(benzoylperoxide)

Light Activated

(Diketone)

(Camphor Quinone)

Activators

Chemically Activated

(Tertiary amine)

Light Activated

(Light)

Inhibitors

Hydroquinone

Hydroquinone

BHT

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Inorganic phase ( dispersed Inorganic phase ( dispersed

fillers)fillers)

•• ImproveImprove thethe mechanicalmechanical propertiesproperties ii..eecompressivecompressive strengthstrength.. ModulusModulus ofofelasticityelasticity andand hardnesshardness andand wearwearresistanceresistance..

•• ReduceReduce polymerizationpolymerization shrinkageshrinkage

•• ReduceReduce thethe coefficientcoefficient ofof thermalthermalexpansionexpansion

•• ImprovesImproves thethe abrasionabrasion resistanceresistance

•• ImprovesImproves opticaloptical propertiesproperties

Inorganic phase ( Inorganic phase (

dispersed fillers)dispersed fillers)

•• Shape:Shape: spherical OR splintered OR spherical OR splintered OR colloidalcolloidal

•• Size:Size: macrofillersmacrofillers

•• --microfillersmicrofillers

•• --hybridhybrid

•• --finefine

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Types of fillersTypes of fillers

••QuartzQuartz: : advantagesadvantages translucent, hard irregularly translucent, hard irregularly

shaped particles, inert shaped particles, inert disadvantagedisadvantage Very difficult Very difficult

to finish and polish high thermal diffusivityto finish and polish high thermal diffusivity

•• PyrogenicPyrogenic silica (silica (aerosilaerosil): ): prepared from silicon prepared from silicon

compounds have very large surface areacompounds have very large surface area

••Barium/Barium/ strontiumstrontium aluminosilicatealuminosilicate glassesglasses

RadiopaqueRadiopaque,, softersofter thanthan quartz,quartz, moremore easilyeasily

polishedpolished developdevelop basicbasic surfacesurface inin waterwater whichwhich

compromisecompromise resinresin fillerfiller bondbond..

••BetaBeta eucryptiteeucryptite

•• ytterbiumytterbium tritri flourideflouride

•• ZirconiumZirconium

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••MACROFILLERS:MACROFILLERS: quartz, quartz,

lithium, lithium, aluminoalumino silicate silicate

glass, barium or glass, barium or

strontiumstrontium

•• Particle size= Particle size= 00..1 1 –– 100 100

microns average microns average 88--1212µµµµµµµµ

•• 7070--80 80 % by weight% by weight

•• MICROFILLERSMICROFILLERS

•• Hydrolyzed silica Hydrolyzed silica

((pyrogenicpyrogenic silica)silica)

•• Average particle size Average particle size

00..0404--00..4 4 µµµµµµµµ 3535--6767%wt.%wt.

•• PrepolymPrepolym microfillermicrofiller. .

ComplexesComplexes

•• HYBRID (BLENDED HYBRID (BLENDED

FILLERS) averageFILLERS) average

•• Fine fillers Fine fillers 00..44--1 1 µµµµµµµµ + +

00..04 04 µµµµµµµµ -- 6060% wt. + % wt. +

microfillersmicrofillers 00..04 04 m. m.

1515% wt% wt 7575--8080% by % by

weightweight

FINE (SMALL FINE (SMALL

PARTICLE)PARTICLE)

Particle size reduced to Particle size reduced to

00..55--33µµµµµµµµ ((11--6 6 µµµµµµµµ))

8080--9090% by wt.% by wt.

Types of Fillers according to Types of Fillers according to

particle size particle size Type of composite resinType of composite resin::By fBy filler sizeiller size

backback

macrofilledmacrofilled

microfilledmicrofilledSP filledSP filled

HybridHybrid

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Micro fillers

• Pyrogenic silica

•Homogenous

• Pre polymerized particles not purely inorganic

Heterogeneous

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Current pattern microfill Current pattern microfill

compositecomposite

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Classification Based on Filler Classification Based on Filler

Particle SizeParticle SizeCLASS of composite

Particle size Filler content W%

Clinical use

Traditional( macro filled)

1-50µmGlass ,quartz

70-80 High stress area

MicrofilledA) HomogenousB) Heterogenous

0.04µm pyrogenicsilica 0.04 µm pyrogenicsilica& prepolymerized resin containing silica

35-4545-79

Low stress & sub gingivalarea requiring high luster and polish

Small Particle filled SPF

1-6 µm glass& 0.04 µm silica

80-90 Moderate stress areaclass III,IV

HYBRID 0.4-1 µm glass and +0.04 µm silica

75-80 High stress areaclass I,II,III, IV

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Surface Roughness Before and After Surface Roughness Before and After Surface Roughness Before and After Surface Roughness Before and After Surface Roughness Before and After Surface Roughness Before and After Surface Roughness Before and After Surface Roughness Before and After

Finishing Finishing Finishing Finishing Finishing Finishing Finishing Finishing Interfacial Phase Interfacial Phase Interfacial Phase Interfacial Phase Interfacial Phase Interfacial Phase Interfacial Phase Interfacial Phase (Coupling Agent)(Coupling Agent)(Coupling Agent)(Coupling Agent)(Coupling Agent)(Coupling Agent)(Coupling Agent)(Coupling Agent)

•• ProvidesProvides aa chemicalchemical bondbond betweenbetween thethe fillerfillerparticlesparticles andand thethe resinresin matrixmatrix

•• SilanesSilanes areare usedused ee..gg.. triethoxytriethoxy vinylvinyl silanesilane•• MoreMore recentlyrecently gammagamma methacryloxymethacryloxy propylpropyl silanesilaneisis usedused..

•• LackLack ofof adequateadequate bondbond------ dislodgmentdislodgment ofof fillers,fillers,andand penetrationpenetration ofof waterwater alongalong thethe fillerfiller--matrixmatrixinterfaceinterface..

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CHEMISTRY OF COMPOSITESInterfacial Coupling Agents

Inhibitors

• Prevents spontaneous

polymer formation

– heat

– light

• Extends shelf life

• Butylated Hydroxytoluene

Phillip’s Science of Dental MaterialsPhillip’s Science of Dental Materials 20032003

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Pigments and UV

Absorbers

• Pigments

– metal oxides

• provide shading and opacity

• titanium and aluminum oxides

• UV absorbers

– prevent discoloration

– acts like a “sunscreen”

• Benzophenone

Phillip’s Science of Dental MaterialsPhillip’s Science of Dental Materials 20032003

Classification:

• According to the curing mode:

– Chemically activated composite resin.

– Light activated composite resin

• According to the size of fillers:

– Macrofilled composite resin.

– Microfilled composite resin.

– Hybrid composite resin.

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Classification according to Classification according to

Polymerization TechniquesPolymerization Techniques

II-- CHEMICALLYCHEMICALLY ACTIVATEDACTIVATED (two(two pastepastesystem)system)

•• InitiatorsInitiators ––benzoylbenzoyl peroxideperoxide

•• ActivatorActivator ––tertiarytertiary amineamine ((dihydroxyldihydroxyl ethylethylpp--toluidinetoluidine))

IIII–– LIGHTLIGHT ACTIVATEDACTIVATED (single(single pastepaste systems)systems)

a)a) ultraultra violetviolet lightlight

b)b) visiblevisible lightlight

IIIIII-- DUALDUAL CUREDCURED COMPOSITECOMPOSITE

ChemicallyChemically andand lightlight togethertogether..

Chemical activated resin

• Two pastes– Initiator Activator

:Benzoyl peroxid :Tertiary amine

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Mode of SupplyMode of Supply

•• TwoTwo pastepaste systemssystems

•• TwoTwo jarsjars aa basebase pastepaste +a+a catalystcatalystpastepaste

•• SingleSingle pastepaste systemssystems

•• DisposableDisposable syringessyringes

•• CompulesCompules withwith colorcolor codedcoded tipstips

•• NN..BB:: aa compositecomposite kitkit maymay alsoalso bebesuppliedsupplied withwith anan acidacid etchantetchant andand aabondingbonding agentagent

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2 2 Jars of composite Jars of composite

pastespastes2 2 Bottles bondBottles bond

Acid EtchantAcid Etchant

Manipulation

1. Etching: 37% phosphoric acid Micro-irregularities

2 .Washing and drying

3.Bonding: Mix drops from 2 bottles of bonding agent mixed

and applied to tooth surface with brush then air dried.

4.Application of composite resin:• Use Plastic spatula

• Bulk or pressure pack tech.

• Celluloid strip

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Disadvantages of chemically

Activated composite:

• Short working time

• Polymerization is inhibited by air.

• Voids: Due to bulk technique

• High polymerization shrinkage

• One Shade

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•• A)A) ULTRA VIOLET ULTRA VIOLET

RADIATIONRADIATION

•• PHOTO INITIATOR=PHOTO INITIATOR=

•• BENZOIN METHYL BENZOIN METHYL

ETHERETHER

•• DISADVANTEGES DISADVANTEGES

•• Limited depth of cureLimited depth of cure

•• HazardsHazards--skin (cancer) skin (cancer)

eye (retinal damage)eye (retinal damage)

•• Intensity fades with time Intensity fades with time

•• B)B) VISIBLE LIGHT VISIBLE LIGHT

(BLUE LIGHT (BLUE LIGHT 468468nm)nm)

•• PHOTO INITIATOR=PHOTO INITIATOR=

•• DIKETONE (E.G DIKETONE (E.G

CAMPHOR QUINONE)CAMPHOR QUINONE)

•• DEAEMA (activator)DEAEMA (activator)

•• ADVANTAGESADVANTAGES

•• Greater depth of cureGreater depth of cure

•• The intensity of the light The intensity of the light

bulb remains constant bulb remains constant

until it failuntil it fail

LIGHT ACTIVATED COMPOSITESLIGHT ACTIVATED COMPOSITESLight Activated Composite Resin:

• Supplied in the form of:

• Single paste system or Compules

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A A Shade guide Shade guide is supplied to determine the shade of the is supplied to determine the shade of the

tooth, hence the composite.tooth, hence the composite.

Manipulation:

– Single component for each step

– Bonding agent is light cured

– Composite resin is applied

incrementally, each increment is

max. 2mm thick. Each increment

is light cured separately with blue

light. This decreases the

polymerization shrinkage of the

composite.

Same as chemical cured composite except for:Same as chemical cured composite except for:

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Advantages of light cured composite

resin Vs Chemical cured one.

• Light Cured

• Easy application No Mixing-

Command cure

– Different shades.

– Incremental application

– Less Polymerization

shrinkage (Incremental

application)

– Less voids, hence higher

strength.

– Long working time.

– Higher color stability.

�� Chemical CuredChemical Cured�� Needs mixing Needs mixing

�� Single shade.Single shade.

�� Bulk Technique applicationBulk Technique application

�� Higher Polymerization Higher Polymerization shrinkage (Bulk tech)shrinkage (Bulk tech)

�� More voids, hence lower More voids, hence lower strength.strength.

�� Difficult applicationDifficult application

�� Short working time.Short working time.

�� Less color stability due to Less color stability due to discoloration caused By discoloration caused By NN,P NN,P toluidinetoluidine

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Polymerization Polymerization

ReactionReaction•• DimethacrylateDimethacrylate

++

•• InitiatorInitiator (peroxide(peroxide OROR diketonediketone ++ blueblue light)light)

++

•• AcceleratorAccelerator (amine)(amine) ++ silanesilane treatedtreated particlesparticles

DentalDental compositecomposite

•• PolymerizationPolymerization isis incompleteincomplete (degree(degree ofofconversionconversion isis 6060 --7575%%

C=CC=C

C=C C=C CC=C=C

C=C C=C CC=C=CC=C C=C CC=C=C

C=C C=C CC=C=C

C=C C=C CC==CCC=C C=C CC=C=C

C=C C=C CC=C=C

C=C C=C CC==CC

C=CC=C

C=CC=C

C=CC=CC=CC=C

C=CC=C

C=CC=C

C=CC=C C=C C=C CC==CCC=C C=C CC==CC

C=CC=C

C=CC=C

polymerizationpolymerization

PolymerizationPolymerization

MonomerMonomer

PolymerPolymer

FerracaneFerracane

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Factors Affecting Depth of Factors Affecting Depth of Factors Affecting Depth of Factors Affecting Depth of Factors Affecting Depth of Factors Affecting Depth of Factors Affecting Depth of Factors Affecting Depth of

CureCureCureCureCureCureCureCure

•• LightLight intensityintensity isis inverselyinversely proportionalproportional

toto thethe distancedistance fromfrom thethe lightlight sourcesource

•• ExposureExposure timetime (not(not lessless thanthan 4040 secs)secs)

•• ShadeShade andand opacityopacity ofof thethe compositecomposite

•• ThicknessThickness 22--22..55mmmm

•• FillerFiller particleparticle sizesize;; thethe smallersmaller particlesparticles

causecause dispersiondispersion ofof lightlight——thereforetherefore

needsneeds longerlonger exposureexposure timetime asas inin

microfilledmicrofilled compositescomposites

Degree of Conversion ( DC)Degree of Conversion ( DC)Degree of Conversion ( DC)Degree of Conversion ( DC)Degree of Conversion ( DC)Degree of Conversion ( DC)Degree of Conversion ( DC)Degree of Conversion ( DC)

•• TheThe percentagepercentage ofof carboncarbon––carboncarbon

doubledouble bondsbonds thatthat havehave beenbeen convertedconverted

toto singlesingle bondsbonds toto formform aa polymericpolymeric

resinresin..

•• HigherHigher DC=DC= HigherHigher strengthstrength ..

•• DCDC dependdepend onon::

••ResinResin compositioncomposition..

••ConcentrationConcentration ofof initiatorinitiator andand inhibitorinhibitor..

••TransmissionTransmission ofof lightlight..

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٣٦٣٦

Degree of Conversion ( DC)Degree of Conversion ( DC)Degree of Conversion ( DC)Degree of Conversion ( DC)Degree of Conversion ( DC)Degree of Conversion ( DC)Degree of Conversion ( DC)Degree of Conversion ( DC)

••TransmissionTransmission ofof lightlight ..

Dental Curing LightsDental Curing Lights

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٣٧٣٧

New Types ofNew Types of

Light SourcesLight Sources

•• Traditional Halogen lightTraditional Halogen light

•• Argon beam laserArgon beam laser

•• Plasma arcPlasma arc

•• Light emitting Diode (LED)Light emitting Diode (LED)

TYPES OF LIGHT SOURCES

• Quartz halogen

Tungstun halogen

lamp produces blue

light radiation at468

nm. After filtering

both IR and UV .

Irradiation is

transmitted through a

fiber optic tip

• Light emitting diodes

(LED)

• Junctions of doped

semi conductors (p-n)

junctions are used for

generation of light

instead of a hot

filament.the spectral

output is within the

absorption of CQ

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٣٨٣٨

WAVELENGTH (nm)WAVELENGTH (nm)

UVUV VisibleVisible IRIRCQCQ

INTRAPULPAL HEAT,INTRAPULPAL HEAT,GINGIVAL IRRITATIONGINGIVAL IRRITATION

INTENSITY

INTENSITY

UV

UV

band

band--pass

pass

filter

filter

IRIR band

band--pass

pass

filter

filter

•• Power SupplyPower Supply•• Cycle Timer (Circuit Board)Cycle Timer (Circuit Board)•• BulbBulb / Reflector/ Reflector•• FilterFilter•• FanFan•• FiberFiber--Optic TrainOptic Train

Advantages and Disadvantages of

Other Light Sources

Argon Laser and Plasma Arc•More specific to the absorption of CQ Shorter exposure times •Higher intensities ( 1000 mW )and shorter curing times 1-3 seconds Disadv: early termination of polymerization reaction lead to less chain length is less average mol w

LED •Developed to overcome problems of QTH •They are light in weight Cable free (Cordless)•NO bulb fails•Higher efficiency than QTH •No need for filters to filter unwanted UV and infra red radiation •No noisy fan and less heat generated •Ergonomic design

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٣٩٣٩

Acid Etch TechniqueAcid Etch TechniqueAcid Etch TechniqueAcid Etch TechniqueAcid Etch TechniqueAcid Etch TechniqueAcid Etch TechniqueAcid Etch Technique

•• BunocoreBunocore 19551955

•• AimAim:: toto overcomeovercome thethe problemproblem ofof micromicroleakageleakage.... ToTo provideprovide aa goodgood bondbondbetweenbetween thethe resinresin andand tooth,tooth, improvesimprovesmarginalmarginal seal,seal, reducereduce marginalmarginal stainingstaining

•• MechanismMechanism:: 3737%% phosphoricphosphoric acidacid liquidliquidoror gelgel givesgives opaqueopaque whitewhite chalkychalkyenamelenamel

•• EtchEtch ((3030secssecs forfor enamelenamel 1515 forfor dentinedentine))--washwash ((4545secs)secs)--drydry ((1515secs)secs) applyapply

Mechanism of Acid EtchingMechanism of Acid EtchingMechanism of Acid EtchingMechanism of Acid EtchingMechanism of Acid EtchingMechanism of Acid EtchingMechanism of Acid EtchingMechanism of Acid Etching

•• RemovesRemoves surfacesurface debrisdebris

•• SelectiveSelective dissolutiondissolution ofof enamelenamel prismsprisms------roughrough porousporous surfacesurface

•• IncreasesIncreases thethe surfacesurface energyenergy ofof enamelenamelandand helpshelps wettingwetting byby thethe adhesiveadhesive

•• IncreasesIncreases thethe surfacesurface areaarea ofof enamelenamel

•• EnamelEnamel bondingbonding agentagent (diluted(diluted BISBIS--GMA)GMA) cancan flowflow andand fillfill thethe producedproducedirregularitiesirregularities bondbond byby mechanicalmechanicalinterlockinginterlocking ResinResin TagsTags

١٤٣٣١٤٣٣//٠٦٠٦//٢٥٢٥

٤٠٤٠

ETCHETCHETCHETCHETCHETCHETCHETCH

Wash & Wash & Wash & Wash & Wash & Wash & Wash & Wash &

drydrydrydrydrydrydrydry

ApplyApplyApplyApplyApplyApplyApplyApply

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٤١٤١

How does composite resin bond to

tooth enamel and dentin?1. Etchant 37% phosphoric acid produces micro-

irregularities in enamel, and opens DT removing the smear layer.

Etched EnamelEtched Enamel

Etched DentinEtched Dentin

••Mechanical Mechanical propertiesproperties

••Polymerization Polymerization shrinkageshrinkage

••Water sorptionWater sorption

••Thermal propertiesThermal properties

••# coefficient# coefficient

••# conductivity# conductivity

••Color stabilityColor stability

••Radio opacityRadio opacity

•• CompressiveCompressivestrengthstrength

•• TensileTensile strengthstrength

•• ModulusModulus ofof elasticityelasticity

•• HardnessHardness

Properties of CompositesProperties of CompositesProperties of CompositesProperties of CompositesProperties of CompositesProperties of CompositesProperties of CompositesProperties of Composites

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٤٢٤٢

Compressive and tensile strengths and E.modulusCompressive and tensile strengths and E.modulus

•• CompressiveCompressive strengthstrengthisis higherhigher forfor finefine andandhybridhybrid duedue toto higherhighervolumevolume fractionfraction ofof fillersfillers

•• LowLow tensiletensile strengthstrengthreflectsreflects brittlebrittle behaviorbehaviorofof compositescomposites

•• ModulusModulus ofof elastictyelasticty forformicrofilledmicrofilled CompositesComposites

•• IsIs ¼¼ thatthat ofof finefineparticlesparticles

••DependsDepends onon thethe amountamount ofof fillersfillers

••ModulusModulus ofof elasticityelasticity ofof microfilledmicrofilled

compositecomposite isis ¼¼ 00rr ½½ thatthat ofof finefine particleparticle

compositecomposite

••HighHigh modulusmodulus isis essentialessential inin highhigh stressstress

bearingbearing areasareas toto minimizeminimize wearwear

••HARDNESSHARDNESS:: relatedrelated toto thethe fillerfiller contentcontent

ratherrather thanthan thethe hardnesshardness ofof thethe fillersfillers

themselvesthemselves

••CanCan bebe measuredmeasured usingusing microindentationmicroindentation

teststests

Modulus of ElasticityModulus of ElasticityModulus of ElasticityModulus of ElasticityModulus of ElasticityModulus of ElasticityModulus of ElasticityModulus of Elasticity

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٤٣٤٣

Polymerization Shrinkage

• Significant role in restoration failure

– gap formation

• secondary caries formation

• marginal leakage

• post-operative sensitivity

• Counteract

– lower shrinkage composites

– incremental placement

– Construct composite inlay

Polymerization ShrinkagePolymerization ShrinkagePolymerization ShrinkagePolymerization ShrinkagePolymerization ShrinkagePolymerization ShrinkagePolymerization ShrinkagePolymerization Shrinkage

Chemically Chemically Chemically Chemically Chemically Chemically Chemically Chemically

activated activated activated activated activated activated activated activated

LightLightLightLightLightLightLightLight

activated activated activated activated activated activated activated activated

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٤٤٤٤

Physical properties

•Polymerized shrinkage–Microhybrid : 1.5-2%

––. . %%22--44 Microfilled :

–Polymerized stress :high as MPa

Self cure Light cureSelf cure Light cure

••Leads to marginal Leads to marginal micro leakagemicro leakage

••To overcome:To overcome:

••Place composite Place composite incrementally ORincrementally OR

••Construct Construct composite composite inlaysinlays either direct either direct (chair side (chair side technique) or technique) or indirectindirect

•• InlaysInlays areare subjectedsubjected totoadditionaladditional curingcuring byby

•• VisibleVisible lightlight

•• VisibleVisible lightlight andand heatheat

•• HeatHeat andand pressurepressure (at(at120120 OOCC andand 66 barbarpressurepressure forfor 1010 minmin..

•• CementationCementation:: dualdualcurecure resinresin cementcement

Polymerization ShrinkagePolymerization ShrinkagePolymerization ShrinkagePolymerization ShrinkagePolymerization ShrinkagePolymerization ShrinkagePolymerization ShrinkagePolymerization Shrinkage

١٤٣٣١٤٣٣//٠٦٠٦//٢٥٢٥

٤٥٤٥

••ConductivityConductivity ofof resinresin compositecomposite ss isis

muchmuch lowerlower thanthan metallicmetallic fillingfilling

materialsmaterials

••TheyThey provideprovide goodgood thermalthermal insulationinsulation toto

thethe pulppulp

••ExpansionExpansion ::thethe higherhigher thethe amountamount ofof

organicorganic matrixmatrix phasephase thethe higherhigher thethe

expansionexpansion

Thermal Conductivity & Thermal Conductivity & Thermal Conductivity & Thermal Conductivity & Thermal Conductivity & Thermal Conductivity & Thermal Conductivity & Thermal Conductivity &

Thermal ExpansionThermal ExpansionThermal ExpansionThermal ExpansionThermal ExpansionThermal ExpansionThermal ExpansionThermal Expansion

١٤٣٣١٤٣٣//٠٦٠٦//٢٥٢٥

٤٦٤٦

••TheThe organicorganic matrixmatrix isis responsibleresponsible forfor

thethe absorptionabsorption ofof waterwater whichwhich isis

accompaniedaccompanied byby swellingswelling ofof compositecomposite

howeverhowever itit isis notnot effectiveeffective inin

counteractingcounteracting thethe effecteffect ofof

polymerizationpolymerization shrinkageshrinkage..

••ThisThis phenomenonphenomenon isis inin partpart responsibleresponsible

forfor discolorationdiscoloration ofof compositecomposite byby waterwater

solublesoluble stainsstains..

Water SorptionWater SorptionWater SorptionWater SorptionWater SorptionWater SorptionWater SorptionWater Sorption

••NotNot allall compositescomposites appearappear radioradio

opaqueopaque inin dentaldental radiographsradiographs..

•• ItIt mustmust containcontain heavyheavy metalmetal elementselements

suchsuch asas bariumbarium ,strontium,,strontium, zirconiumzirconium

toto bebe radioradio opaqueopaque inin dentaldental

radiographicradiographic filmsfilms..

Radio OpacityRadio OpacityRadio OpacityRadio OpacityRadio OpacityRadio OpacityRadio OpacityRadio Opacity

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٤٧٤٧

Factors Contributing to Wear

••PorosityPorosity

••Filler content and filler particle sizeFiller content and filler particle size

••Degree of polymerizationDegree of polymerization

••HardnessHardness

•• Interfacial bondingInterfacial bonding

••Position of tooth in the dental archPosition of tooth in the dental arch

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Properties of CompositesProperties of CompositesProperties of CompositesProperties of CompositesProperties of CompositesProperties of CompositesProperties of CompositesProperties of Composites

Property Property MicrofineMicrofine Hybrid Fine Hybrid Fine MacrofilledMacrofilled

•• Filler Filler 2020--55 6055 60--65 6065 60--77 5077 50--6565

Content Content

VolVol %%

•• PolymPolym. . 22--4 14 1..55--4 14 1--11..7 17 1--11..77

Shrink %Shrink %

•• Coefficient Coefficient 5050--68 2068 20--40 1940 19--38 1738 17--3535

Thermal expThermal exp

OCxOCx101066

•• Water Water sorpsorp 11..22--22..2 02 0..55--00..7 07 0..33--00..6 06 0..33--00..77

mg/cmmg/cm22

..

..

..

..

PropertiesClassification

Hard, rough surfaces over time,

abrades enamel and poor wear

resistance; difficult to polishMacrofilled (Traditional)

Poor mechanical properties (use

in low stress areas), excellent for

polishing, decreased shrinkage,

increased wear resistance but

debatable

Microfilled

Good mechanical properties,

better polishes than macrofilled,

better

wear resistance than microfilled

Hybrid

Better polish, mechanical

properties similar to hybrids.

Continuum filled Better polish,

mechanical properties similar to

hybrids

Micro-Hybrid

Good mechanical properties,

excellent polishNanofilled.

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Applications: (uses)Applications: (uses)

-- AsAs anan anterioranterior restorativerestorative materialmaterial forfor classclass IIIIII &&classclass IVIV (especially(especially microfilledmicrofilled composites)composites)

-- HybridsHybrids cancan nownow bebe usedused inin smallsmall classclass IIII andandclassclass II (especially(especially radiopaqueradiopaque types)types)

-- AsAs corecore buildbuild upup materialsmaterials

-- AsAs laminatelaminate veneersveneers << facialfacial && labiallabial surfacessurfaces ofofnaturalnatural teeth)teeth)

-- ForFor cementationcementation ofof resinresin bondedbonded bridgesbridgesmarylandmaryland && rochetterochette typestypes

-- DiastemaDiastema closureclosure

-- CementationCementation ofof orthodonticorthodontic bracketsbrackets

-- PitPit && fissurefissure sealantssealants

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٥٠٥٠

UnfinishedComposite Surface Finished

Composite SurfaceEnamelSurface

EtchedEnamel Rods

Voids atMargins

SilicateReinforcing Filler

CrosslinkedResin Matrix

COMPOSITE

INTERFACEINTERFACE INTERFACE

INTERFACE

INTERFACE

DEFINITION OF COMPOSITEPhases and Interfaces

50 v/o filler = 75 w/o filler

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Different Types of Composites according to Filler Different Types of Composites according to Filler Different Types of Composites according to Filler Different Types of Composites according to Filler Different Types of Composites according to Filler Different Types of Composites according to Filler Different Types of Composites according to Filler Different Types of Composites according to Filler

Particle SizeParticle SizeParticle SizeParticle SizeParticle SizeParticle SizeParticle SizeParticle Size

١٤٣٣١٤٣٣//٠٦٠٦//٢٥٢٥

٥٢٥٢

Different Types of Composites according to Filler Different Types of Composites according to Filler Different Types of Composites according to Filler Different Types of Composites according to Filler Different Types of Composites according to Filler Different Types of Composites according to Filler Different Types of Composites according to Filler Different Types of Composites according to Filler

Particle SizeParticle SizeParticle SizeParticle SizeParticle SizeParticle SizeParticle SizeParticle Size

MEGAFILL MACROFILL MIDIFILL MINIFILL MICROFILL NANOFILL

Not

Shown

Not

Shown

DifferentFiller Particle

Sizes

HYBRID(MIDIFILL)

HYBRID(MINIFILL)

MixturesOf FillerSizes

Hetero-geneousMIDIFILL

Hetero-geneousMINIFILL

Hetero-geneousMICROFILL

Not

Shown

Not

Shown

MixturesOf Pre-Cured

Pieces ofComposite

FILLER PARTICLESSchematic Examples

HOW DO YOU MAKE FILLERS?• Crushing, Grinding, Sieving

• Vapor Phase Condensation

• Sol-Gel Precipitation

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٥٣٥٣

••FlowableFlowable::

••Reduced filler level to Reduced filler level to allow the material to flow allow the material to flow readily and adapt readily and adapt intimately to cavity wall.intimately to cavity wall.

••More susceptible to wear More susceptible to wear

••Lower strengthLower strength

••Used as liner and in class Used as liner and in class V cavitiesV cavities

••Packable :Packable :

••Contain elongated fibrous Contain elongated fibrous filler particles(filler particles(100 100 micron in micron in length which may be length which may be textured to resist flow and textured to resist flow and interlock with the resininterlock with the resin

••Sculpt able and non Sculpt able and non slumping similar to slumping similar to amalgam in placement amalgam in placement techniquetechnique

••Less sticky Less sticky

••Used in large posterior Used in large posterior restorations to establish restorations to establish contact areas and occlusal contact areas and occlusal anatomy.anatomy.

Packable and Packable and Packable and Packable and Packable and Packable and Packable and Packable and FlowableFlowableFlowableFlowableFlowableFlowableFlowableFlowable CompositesCompositesCompositesCompositesCompositesCompositesCompositesComposites

١٤٣٣١٤٣٣//٠٦٠٦//٢٥٢٥

٥٤٥٤

Coupling agent

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Visible-Light Activation

• single paste in an opaque syringe

• Photo-initiator (camphorquinone ) reacts

with amine activator

• Forms free radicals

• Initiates addition polymerization

– monomer

• Bis-GMA

••Direct viewing will Direct viewing will

damage the eyedamage the eye

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TYPES OF LIGHT SOURCES

• PLASMA ARC

• A xenon short arc lamp is used for curing

• DC. Discharge is passed between two electrodes in a gas which become ionized producing a combination of electrons &+ve ions

• ARGON LASER

• Beams of photons

emitted in phase. The

emission wave length

corresponds to the

absorption spectrum

of CQ

Methods of CuringMethods of Curing

•• SoftSoft startstart oror RampedRamped:: 11stst stepstep (initial(initialcure)cure) slowslow irradiationirradiation atat lowlow energyenergy ee..gg..atat 150150mW/mW/ cmcm22 toto reducereduce earlyearly stiffeningstiffeningandand contractioncontraction stressstress buildbuild upup andandpromotepromote marginalmarginal integrityintegrity

•• 22ndnd stepstep (final(final cure)cure) prolongedprolonged irradiationirradiationatat higherhigher energyenergy 650650 mWmW/cm/cm22 toto achieveachievebetterbetter physicalphysical andand mechanicalmechanicalpropertiesproperties

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Methods of Curing (cont.)Methods of Curing (cont.)

PulsePulse delaydelay::•• InitialInitial curecure atat 200200mW/mW/ cmcm22 forfor 33 secssecs..33 minutesminutes RESTREST..

•• FinalFinal curecure atat 500500--600600mW/mW/ cmcm 22 forfor 3030secssecs..

Visible light source

• The radiation beam is transmitted to the

tooth surface by a quartz rod.

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٥٨٥٨

Photo-initiator

• Camphorquinone (CQ)

– most common

photo-absorbing material

– maximum sensitivity

• blue range (465 nm)

Aim of Light Curing

1. Short irradiation time.

2. Low shrinkage stress.

3. Uniform degree of

conversion of polymer

throughout the whole

mass of composite.

4. To overcome the problems of chemical

activation, such as air incorporation in the mix

leading to porosity and oxygen inhibition of

polymerization and uncontrolled working time.

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Advantages of Light Cure Advantages of Light Cure

Vs . Chemical CureVs . Chemical Cure

•• CompleteComplete controlcontrol overover workingworking timetime

(command(command cure)cure)

•• NoNo mixingmixing–– lessless voidsvoids withinwithin thethe massmass

•• LessLess finishingfinishing timetime

•• MoreMore colourcolour stablestable andand wearwear resistantresistant

•• DisadvantagesDisadvantages extraextra costcost ofof lightlight curingcuring

unitunit--depthdepth ofof curecure dependsdepends onon shadeshade andand

opacityopacity--highhigh intensityintensity …… hazardhazard toto thethe eyeeye

Manipulation of Chemically Activated Manipulation of Chemically Activated Manipulation of Chemically Activated Manipulation of Chemically Activated Manipulation of Chemically Activated Manipulation of Chemically Activated Manipulation of Chemically Activated Manipulation of Chemically Activated

CompositesCompositesCompositesCompositesCompositesCompositesCompositesComposites

SelectSelect properproper shadeshade..

InIn deepdeep cavitiescavities placeplace calciumcalcium hydroxidehydroxide oror glassglass ionomerionomercementcement..

NeverNever useuse eugenoleugenol containingcontaining cementscements asas theythey inhibitinhibitpolymerizationpolymerization ofof compositescomposites..

AvoidAvoid crosscross contaminationcontamination (double(double--endedended plasticplasticspatula)spatula) avoidavoid metalmetal spatulasspatulas

TwoTwo pastespastes systemsystem:: equalequal volumesvolumes areare mixedmixed onon paperpaperpadpad mixingmixing timetime 2020--3030 secssecs

WorkingWorking timetime 11..55--22 minmin–– settingsetting ==33--55 minmin

AvoidAvoid trappingtrapping voidsvoids;; bulkbulk packpack techniquetechnique

ContourContour:: celluloidcelluloid ((mylarmylar)) stripstrip

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٦٠٦٠

Light Activated Light Activated Light Activated Light Activated Light Activated Light Activated Light Activated Light Activated

Systems ManipulationSystems ManipulationSystems ManipulationSystems ManipulationSystems ManipulationSystems ManipulationSystems ManipulationSystems Manipulation

•• SelectSelect properproper shadeshade..

•• InIn deepdeep cavitiescavities placeplace calciumcalciumhydroxidehydroxide oror glassglass ionomerionomer cementcement..

•• NeverNever useuse eugenoleugenol containingcontainingcementscements asas theythey inhibitinhibit polymerizationpolymerizationofof compositescomposites..

•• PlacePlace compositecomposite inin incrementsincrements 22mmmm..EachEach curecure forfor 2020--4040 secssecs..

•• AfterAfter 22--66minmin.. StartStart finishingfinishing andandpolishingpolishing..

INCREMENTAL PLACEMENT TECHNIQUESINCREMENTAL PLACEMENT TECHNIQUES

•• ObliqueOblique incrementalincremental

•• LateralLateral incrementalincremental

•• Directional curing Directional curing technique(light technique(light transmitting wedges and transmitting wedges and transparent matrices)transparent matrices)

•• AimAim ::minimizingminimizing adverseadverseeffecteffect ofof polymerizationpolymerizationshrinkageshrinkage

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٦١٦١