Download - Fillers in composite resins
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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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