Fillers in composite resins

GOOD AFTERNOON!!!!!

FILLERS IN COMPOSITE RESINSDEEPTHI P.R.FINAL YEAR BDS

IntroductionMaterials usedTypes of FillersMethods of PreparationMethods of IncorporationFunctions of Fillers Factors Influencing the Functions

of Fillers

Advantages & Drawbacks of different Materials

Classification of Composite Resins based on Fillers

Recent AdvancesSummaryReferences

INTRODUCTION

Composite In materials and science, a solid

formed from two or more distinct phases that have been combined to produce properties superior to or intermediate to those of the individual constituents

Dental CompositeHighly cross-linked polymeric

materials reinforced by a dispersion of glass, crystalline or resin filler particles and/or short fibers bound to the matrix by silane coupling agents

Dr. Ray L. Bowen (1962)

Basic ComponentsMatrixFillerCoupling agent

FILLERS

‘The inorganic and/or organic resin particles that are designed to strengthen a composite, decrease thermal expansion, minimize polymerization shrinkage and reduce the amount of swelling caused by water sorption’

FILLERSDispersed phase of composite

resins

1950’s- Quartz in MMA filling materials

MATERIALS USEDQuartzAmorphous SilicaGlass fillers with metalsColloidal SilicaCeramicsOrganically modified

Ceramics/ORMOCERS

TYPES OF FILLERS3 filler categories- 35 years

ConventionalMicrofineHybrid

CONVENTIONAL FILLERIrregular glass or ceramic4µm - 40µmUsed in 1960’s- 1970’sFirst generation Composites: 1-

50µm 60-80 wt%Currently: 1-5µmBa, Sr, Zn, Yb glasses- fine fillers -Radiopacity

MICROFINE FILLER

Pyrogenic silica: 0.01µm- 0.1µmColloidal silica30-60 wt%Rare earth metal compounds-

RadiopacityHomogeneous & Heterogeneous

HYBRID FILLERConventional glass/ ceramic filler

particles-Zirconia/ Silica: 0.5µm - 10µmPyrogenic silica: 0.01µm - 0.1µmBariumaluminoborate & Sr

glasses- Radiopacity78-85 wt%

MEGAFILLER

Pieces of glass: 0.5mm – 2mmInsertsComposites at points of heavy

occlusal contact or high wear

METHODS OF PREPARATIONGrinding or milling Quartz/

Glasses: 0.1µm-100µm

Microfillers:Pyrolytic or Precipitation process

fumed silica- SiCl4 in O2 & H2 macromolecule

chains of SiO2

METHODS OF PREPARATION

Colloidal particles of Sodium silicate to water & HCl colloidal silica

Organic fillers: Pulverized precured resin:5µm-

30µmSilane treated colloidal silica to the

monomer at slightly elevated temperature

METHODS OF PREPARATION

Composite paste heat cured with Benzoyl Peroxide

Cured composite : ground into particles of size larger than traditional

fillers

METHODS OF INCORPORATION

CONVENTIONAL FILLER PARTICLES Surface coating of ‘Coupling

agent’Then blended with resin

MICROFILLER PARTICLESOrganic fillers + silane treated

colloidal silica blended with monomer

METHODS OF INCORPORATION

1. Homogeneous :Microfiller loaded directly to the resin

2. Heterogeneous Microfiller compressed into clumps:Sintering, precipitation, silanization or

condensationFumed silica added to a heated resin

at ~70 wt%

METHODS OF INCORPORATION

Increase Filler loading Sinter colloidal silica particles:

Several tenths of a µm Reduces compromise in the

rheology Grinding prepolymerized

composite highly loaded with colloidal silica particles

Particles then incorporated

FUNCTIONS OF FILLERSStrengthen the compositeReduce the amount of matrix

materialReinforcement of the matrix

resin: increased hardness, strength & decreased wear

Reduction in polymerization shrinkage

FUNCTIONS OF FILLERSImproved workability by

increasing viscosityReduction in water sorption,

softening & stainingIncreased radiopacity &

diagnostic sensitivity

FUNCTIONS OF FILLERSReduction in thermal expansion &

contractionIncreased compressive strength,

tensile strength, modulus of elasticity

Increase in abrasion resistanceIncreased fracture toughness

FUNCTIONS OF FILLERSEnhances physical & mechanical

properties to the level of tooth tissue clinical performance & durability

Increases translucency

Improves handling properties

FACTORS INFLUENCING THE FUNCTIONS OF FILLERS

FILLER SIZELarge : ‘plucking’ – rough surface - increased wear - reduced flexural strengthSize can’t be reduced beyond

limits- technical problems

FACTORS INFLUENCING THE FUNCTIONS OF FILLERS

INCORPORATION OF RADIOPAQUE COMPOUNDS

Sr/Ba glass & other heavy metal compounds

Rare earth metal compounds

FACTORS INFLUENCING THE FUNCTIONS OF FILLERS

FILLER CONTENTAs it increases:Reduced polymerization

shrinkageCoefficient of thermal expansion-

more like tooth structureIncreased hardness & abrasion

resistance

FACTORS INFLUENCING THE FUNCTIONS OF FILLERSIncreased color stabilityIncreased depth of cureIncreased stiffnessReduced resistance to toothbrush

abrasion & wear by hydroxyapatite

SILANE COATINGIncreased resistance to hydrolytic

degradation

FACTORS INFLUENCING THE FUNCTIONS OF FILLERSFILLER SHAPESpherical shape: Incorporates more inorganic fillersImproves fracture strength

REFRACTIVE INDEXMatches that of resin ~ 1.50Translucency similar to the tooth

structure

ADVANTAGES & DRAWBACKS

FILLER ADVANTAGES DRAWBACKS

Quartz .Clinically inert (insoluble).Strong & hard.Difficult to grind into very fine particles.Adequate Refractive index.Highly esthetic

.Difficult to polish

.Potentially abrasive to opposing teeth or restorations

Amorphous silica

.Composition & Refractive index same as quartz

.Less hard

.Not crystalline

Glass fillers with heavy metals

.Adequate Refractive index

.Provide radiopacity.Not as inert as quartz & amorphous silica.Leaches &weakens in acidic juices & oral fluids.More susceptible to wear.Shorter functional lifetime .Attacked by APF gels/solutions

CLASSIFICATION OF COMPOSITES BASED ON FILLERS

I. Based on the filler particle Size & Size Distribution

Traditional (large particle) 1-50 µm Hybrid (large particle) : (1) 1-20 µm glass (2) 0.04 µm silica Hybrid (midifiller) : (1) 0.1- 10 µm glass (2) 0.04 µm silica

Hybrid (Minifiller/ Small Particle Filled):

(1) 0.1-2 µm glass (2) 0.04 µm silica

Packable Hybrid: Midifiller/ Minifiller Hybrid but with

lower filler fraction

Flowable Hybrid: Midifiller Hybrid, but with finer

particle size distribution

Homogeneous Microfill: 0.04 µm silica

Heterogeneous Microfill: (1) 0.04 µm silica (2) Prepolymerized

resin particles containing 0.04 µm silica

II. According to Skinner Traditional/Conventional: 8-12 µm Small Particle Filled Composites: 1-

5µm

III. Philips & Lutz Classification Macrofiller Composites: 0.1- 100

µm Microfiller Particles: 0.04 µm Hybrid Composites: different sizes

IV. Based on Mean Particle Size of the filler

Traditional Composite resinsHybrid Composite resinsHomogeneous Microfilled

CompositesHeterogeneous Microfilled

Composites

V. According to Bayne & Heyman

Megafill : 1-2mmMacrofill: 10-100µmMidifill: 1-10µmMinifill: 0.1-1µmMicrofill: 0.01-0.1µmNanofill: 0.005-0.01µm

VI. Williams ClassificationDensified Composite Midway

filledUltrafine Midway filledFine Midway filledUltrafine cement filledFine cement filled

Homogeneous Microfine Composite

Heterogeneous Microfine Composite

With splintered prepolymerized filler

With agglomerated prepolymerized filler

With spherical prepolymerized filler

RECENT ADVANCES

NANOFILLED COMPOSITESNanomers (5nm-75nm) &

‘nanocluster’ agglomerates (0.6 µm -1.4 µm)Primary Zirconia/ Silica

nanoparticles(5nm-20nm) fused; infiltrated with silane

‘Nanohybrid’ Composites: Incoporation of nanoparticles into composite formulations

RECENT ADVANCES

PROPERTIES :Nanofilled vs OthersPhysical & mechanical- similar to

microhybridWater sorption similar to midifill

& microfillSignificantly better polish & gloss

retentionLower solubilityReduced scattering of curing light

RECENT ADVANCESNanohybrid variety :- properties similar to / better than

microhybrid- inferior compared to nanofilledNanodiamond filler:Improve wear resistance & flexural

strength in proportions of 0.005%-0.008%

RECENT ADVANCES

FLAKE SHAPED GLASS FILLER(FSG)

Thin glass platelet with a flat, smooth surface

Good transparencyIncreased hardnessCompressive strength ~

commercial compositeHigh flowability

RECENT ADVANCES

POLYMETHYLMETHACRYLATE(PMMA) FILLER PARTICLES2wt% additional PMMA fillersInhibit crack propagationEnhance compressive strengthNo significant change in water

sorption/ water contact angle of the surface

RECENT ADVANCES

SILANE COATED GLASS FILLERSFluoroboroaluminosilicate glass

coated with3-

methacryloxypropyltrimethoxysilane

Or 3-aminopropyltrimethoxysilaneGreater amount of fluoride

releaseHigher pH value

RECENT ADVANCES

LEUCITE CONTAINING CERAMIC FILLER

IPS Empress ingots ball milled; passed through an 800 mesh sieve

Significant wear resistance

SUMMARYFillers – reduce curing shrinkage-- improves physical propertiesComposite characteristics change:- Material- Size & size distribution- Load- Shape- Surface modifiers- Optical index

REFERENCESPhilip’s Science of Dental

Materials- Anusavice,11th EditionApplied Dental Materials-John F

McCabe & Angus,W.G.Walls,8th Edition

Introduction to Dental Materials- Richard van Noort,2nd Edition

Tooth colored Restoratives, Principles & Techniques- Albers,9th Edition

REFERENCESThe Clinical Handing of Dental

Materials-Smith,Wright,Brown,2nd Edition

Clinical aspects of Dental Materials-Gladwin&Bagby

Dental Materials-Carol Dixon,Hatrick,Eakle

Dental Materials- John M Prowers,John C.Wataha

REFERENCES

Sturdevant’s Art & Science of Operative Dentistry- 4th Edition

Textbook of Operative Dentistry- Nisha Garg & Amit Garg

Textbook of Dental Materials-Sharmila Hussain

REFERENCESConstantinos Masouras et alDental Materials Vol 24 No.7 July

2008: 932-939Lim YK et alDental Materials Vol 24 No.1

January 2008Tahimoto Y et alActa Biomaterials 2006 Nov;2(6):

633-639

REFERENCESKondo Y et alDental Materials J,2010 October

14;29(5): 596-601Itota T et alDental Materials J,2010 August

7;29(4):362-368Arikawa H et alDental Materials J,2007 Jan

26(1):38-44

REFERENCESH St.Germain et alJournal of Dental Research Feb

1985 Vol64 No.2:155-160Dr Moraes RR et alOperative Dentistry 2009 Sep-

Oct;34(5):551-557Berger SB et alBrazil Dental Journal

2009;20(4):314-318

REFERENCESJ. Mat.Sci.Mater Med.2007

Jun;18(6):1157-1162 Clinical Materials Review Inside Dentistry July/August 2007

Vol 3,Issue 7Motohiro UO et alJournal of the Ceramic Society of

Japan,Vol 118 (2010), No.1378 June :425-427

REFERENCESZhong –Yu- Xiu et alEffects of Nanodiamond Filler on

Compressive strength & Microhardness of Composite Resins

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