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Restorative materials used in paediatric dentistry
RESTORATIVE MATERIALS USED IN PAEDIATRIC DENTISTRY (Along with Recent Advancements)GUIDED BY - PRESENTED BY -Dr. Jitendra Kamini Singh B.D.S. 3rd year
CONTENTS INTRODUCTION: NEED FOR DECIDUOS DENTITION IN CHILDREN NATURE OF RESTORATIVE MATERIALS USED IN PAEDIATRIC DENTISTRY REQUIREMENT OF AN IDEAL RESTORATIVE MATERIAL VARIOUS RESTORATIVE MATERIALS USED IN PAEDIATRIC DENTISTRY:GLASS IONOMER CEMENTCOMPOSITE RESINSAMALGAMLINING MATERIALS
CONTENTSRECENT ADVANCEMENTS IN RESTORATIVE MATERIALS USED IN PAEDIATRIC DENTISTRY• ALTERNATIVE TO AMALGAM• RECENT ADVANCEMENTS IN FIELD OF COMPOSITE RESIN RESTORATIVE MATERIAL• RECENT ADDITIONS TO G.I.C.• SMART MATERIALS
INTRODUCTION : NEED FORRESTORATION IN PAEDIATRIC DENTISTRY• Preservation Of Deciduous Teeth Until Their Normal Exfoliation Is Essential Because:1)They are considered essential in the development of theoral cavity and maintaining a healthy oral environment freeof pain.a) In adulthood , the face and jaws are smaller size are present ,which are known as Deciduous or Primary teeth.b) With the growth , the jaw bones grow in size but the teeth once fully formed do not grow in size. Hence , permanent teeth of large sizes erupt in oral cavity, replacing deciduous teeth of smaller size.
INTRODUCTION : NEED FORRESTORATION IN PAEDIATRIC DENTISTRY2) They provide a guide for permanent tooth eruption.3) The root of deciduous teeth provides an opening forthe permanent teeth to erupt.4) These teeth also help in speech and mastication.6) Promote an aesthetic appearance.7) Maintenance of arch length.
Nature of Restorative Materials Used In Pediatric dentistryIn view of the limited lifespan of the deciduous teeth,plastic restorative materials are used, which can beplaced directly into the cavity, especially for the firstmolars because of the difficulties which may beencountered in placing restorations such as gold inlaysor gold foils in a young patient.
Requirements of an Ideal Restorative Material1) Restoration of aesthetic2) Maintenance of physical strength of the crown.3) Preserving the anatomy of the occlusal surface and thus preserving the inter arch relationship with the opposing and adjacent teeth.4) Prevention of further ingress of bacteria or their byproducts into the micro spaces between the restoration and tooth.5) Long term adhesion between the restoration and tooth to ensure complete isolation.
Various Restorative Materials used in Pediatric Dentistry1) Glass Ionomer Cement2) Composite Resins3) Amalgam
Glass Ionomer CementThis material was developed by Wilson and Kent in1971.• These are adhesive tooth color anticariogenic restorative material.• It can be used as a luting cement, a lining under another restorative material or as a restoration.• It also known as Poly Alkenoate Cement and Alumino Silicate Polyacrylic Acid (ASPA)
Classification of Glass Ionomer Cement – On the basis of use: • Type I: For Luting Cements • Type II: For Restorations • Type III: Liners and Bases • Type IV: Fissure Sealants • Type V: Orthodontic Cement • Type VI: Core Build Up • Type VII: Fluoride Releasing • Type VIII: ART (Atraumatic Restorative Technique) • Type IX: Deciduous Teeth
Classification of Glass Ionomer Cement• According to other uses: – For Intermediate Restoration – In Sandwich Technique (As Adhesive Cavity Liners) – In ART (Atraumatic Restorative Technique) – In Deciduous Tooth
Classification of Glass Ionomer Cement• Chemical Classification1) Conventional Glass Ionomer Cement2) Resin Modified Glass Ionomer Cement (Conventional with addition of HEMA)3) Hydrate Ionomer Cement (Also known as Dual Cure Glass Ionomer Cement)4) Tri Cure Glass Ionomer Cement5) Metal Reinforced Glass Ionomer Cement
Classification of Glass Ionomer Cement • Widely Accepted Classification of Glass Ionomer Cement • Type I: Luting Used in cementation of crowns, bridges and orthodontic devices Powder : Liquid is approximately 1.5:1 Radio Opaque • Type II: Restorative • Type IIA: Restorative Aesthetic – Used in all types of aesthetic restoration – Auto Cure or Resin Modified – Powder: Liquid is 3:1 or greater – Radio Opaque generally – High physical properties
Classification of Glass Ionomer Cement – Type IIB: Restorative » Restoration under high occlusal load » Auto cure or resin modified » Powder : Liquid is 3:1 or greater » Radio Opaque » Used as a denting substitute or as interim restoration. • Type III: Lining or Base – Simple lining under metallic restoration – Powder: Liquid is 1.5:1 – Auto Cure – Radio Opaque – High Strength bases for lamination technique.
Composition of Glass Ionomer CementGlass = Formulation of glass powderIonomer = Ionomeric Acid with Carboxyl groupThe three essential constituents of dental Ionomerglasses are –Silica (Si02), Alumina (Al2O3) and Calcium Fluoride(Cafl2) or Fluorite CaF2)Glass Ionomer Cement is a product of an Acid-Basereaction.
Composition of Glass Ionomer CementPowder• The basic component is a Calcium Alumino Silicate Glass containing fluoride.Its constituents are: Calcium Fluoro Alumino Silicate Glass, Lanthanum, Strontium, Barium or Zinc Oxide• It is possible to substitute the Calcium with Strontium and the percentage of Fluoride in the formula can be varied.• Phospate can be added to decrease the melting temperature and modify the setting characteristics.• Fine colloidal Silver can be sintered to the particles and amalgam alloy particles can be added to the mix in an attempt to enhance the properties.
Composition of Glass Ionomer CementLiquidLiquid is essentially a poly Alkenoic Acid.• The usual acid is 40-55% solution of 2:1 poly acrylic or Itaconic acid copolymer in water or a copolymer of malic acid and poly acrylic acid.• Its constituents are – – Poly Acrylic Acid – Itaconic Acid (Increases the reactivity and reduces the viscosity and tendencies for gelation) – Maleic Acid or Tricarboxylic Acid – Tartaric Acid – Improves handling characteristics, increases viscosity and working time and reduces setting time.
Composition of Glass Ionomer CementRole of Fluoride in Glass Ionomer Cement• It lowers the temperature of fusion• Improves the working characteristics of the cement paste• It increases markedly the strength of the set cement• In moderate amount it enhances translucency• Contributes to therapeutic value of the cement by releasing fluoride over a prolonged period.
Setting reaction of Glass Ionomer Cement– When the glass ionomer cement powder and liquid are brought together to form a paste the glass powder which is basic reacts with liquid, that is Acid, to form a salt hydrogel which is the binding matrix– Here water in the reaction medium forms a part of Hydrogel.
Different Stages in the Setting reaction– Initially the surface of glass is attacked resulting in decomposition of glass and release of aluminum and calcium ions– These aluminium and calcium ions then migrate into the aqueous phase of the cement– As the reaction proceeds the concentration of ions and the viscosity of the paste increases– Initially calcium ions form part of the cross linkage with poly acrylic acid change to form solid mass.
Different Stages in the Setting reaction• Later within next 24 hours new phase is formed with aluminium ions becoming bound to cement matrix leading to more rigid set cement• Calcium polyacrylate is responsible for final hardening of the matrix.• Sodium and Fluoride do not participate in the cross linking of the cement• Some sodium ions may replace Hydrogen ions of carboxylic group, but rest combine with fluoride to form NaFl which is uniformly dispersed
Different Stages in the Setting reaction within the cement. – Unreacted glass particles are coated by silica gel (that form during removal of the cations from the surface of the particles) – Final set cement consists of agglomerated unreacted powder particles surrounded by a silica gel in an amorphous matrix of hydrated calcium and aluminium polysalts. ROLE OF MOISTURE CONTAMINATION AND DEHYDRATION During the setting process the cement should to protected from two extremes-dessiccation and aqueous environment.
ROLE OF MOISTURE CONTAMINATION AND DEHYDRATION• This can be achieved in an atmosphere of 80% relative humidity.• The cement should be protecting by varnish or petroleum jelly.• After initial set but before the cement is fully hardened a proportion of cement containing Aluminium Calcium , Fluoride and Polyacrylate containing ions are in a soluble form and so can be dissolved out of the cement by aqueous fluid leading to permanently weakened cement.
ROLE OF MOISTURE CONTAMINATION AND DEHYDRATION• If at this stage water is released out due to excessive drying restoration will lose aesthetic appeal ,shrink and become brittle.• It may take one hour until the cement remains vulnerable to moisture.• Hardening continues for 24 hrs.• Slow maturation continues over the period of months and becomes more rigid and gather strength.
FACTOR AFFECTING SETTINGCHARECTERSTICS OF GLASS IONOMERCEMENTRole Of Fluorides: Fluoride forms metal complexesthat restore the binding of cations to anionic sites onthe polyelectrolyte chain and thereby delaying gelationand prolonging working time. It also delays pHdependent gelation .ROLE OF TARTARIC ACIDIt improves manipulation of the cement and increasesthe strength of set cement.
FACTORS AFFECTING RATE OF SETTING OF GLASS IONOMER CEMENT• Glass composition -especially the Al2O3 / SiO2 ratio and fluoride content.• Fluoride prolongs the working time. Increased ratio –faster is the set , shorter is the working time.• Particle size- Finer the particles size-Faster is the set and shorter is the working time..• Addition of tartaric acid sharpens the set without shortening the w.t• Relative proportion of constituents in the cement mix i.e. glass / polyacid /tartaric acid / water .• Greater proportion of glass and lower is the working time.• Temperature of mixing-In higher temperature the faster is set shorter is w.t.
PROPERTIES OF GLASS IONOMER CEMENT•Physical Properties•Sets rapidly in the mouth•Initial compressive strength is low (24 hrs.)-6.6MPa•Hardness-70KHN•Solubilty-0.7%•Bioactive and possesses chemical bonding with thetooth.•Coefficient of thermal expansion is close to that oftooth causing less micro leakage around the restoration.
PROPERTIES OF GLASS IONOMER CEMENTESTHETICSTranslucent materialColor is more stable. Resistance to stain is dependent ongood surface finish.ADHESIONPermanently adheres to the unreacted enamel and dentinchemically.Principle barrier to adhesion is water.Mechanism of adhesion-chelation of carboxyl group of thepolyacids with the calcium ions in the apatite of enamel anddentin forming strong ionic bonds which increases thestrength as the material sets.Surface conditioning also improves adhesion.
PROPERTIES OF GLASS IONOMER CEMENTBIOCOMPATIBILTYo Excellent marginal seal and fluoride release-Reducing the risk of secondary caries.o Continuous Fluoride release occurs around the restoration- tooth interface(3mm) for a period of 18 months.o Acid groups are attached to the polymer molecule which have limited diffusibilty , hence the pulp affects are limited to areas immediate . It adjacent to the material.o When fluid filled dentinal tubules are in direct contact with the unset material and problem occurso High ionic concentration in the material cause dentinal fluid to rapidly diffuse outward into the cement producing a change in the pulpal pressure creating pain and sensitivity.o Hydrogen ions may move into the tubules towards the pulp and cause chemical irritation.o When the dentin thickness is less there is less fluid to buffer the acid.o Inflammatory response of pulpal tissue towards G.I.C. is more than Zinc Phospate cement and resolves in 20 days without formation of reparative dentin.o It is said that lining of calcium hydroxide or zinc oxide eugenol is required , when less than 0.5-1mm of sound dentin remains over the pulp.
MODIFIED GLASS IONOMER CEMENT ”ANHYDROUS”• In this modification , the liquid is delivered in a freeze dried form that is incorporated in powder. The liquid to be used is clean water only and this may enhance shelf life and facilitating mixing.• Another alternative is to use a dilute tartaric acid as the liquid with dehydrated polyacrylic acid included in the powder.• These alternatives makes it possible to use a polyacrylic acid with a higher molecular weight, thus improving physical properties.• The term anhydrous is actually a misnomer as its not possible for ion transfer to occur in any material in the absence of water.
RESIN MODIFIED GLASS IONOMER CEMENT• These are materials which have a small quantity of a resin into the liquid formula.• Less than 1% of photo initiators are allowed for the setting reaction to be initiated by light of the correct wavelength .• The advantages include early resistance to water uptake in the nearly set cement as well as enhanced translucency.• The resin utilized in these materials is Hydroxy Ethyl Meth Acrylate(HEMA) and its incorporated into the liquid in about 15-25% so as to have a powder liquid ratio of about 3:1
NANO IONOMERS• Nano-ionomers delivers greater wear resistance , esthetics and polish compared to other glass ionomers while affecting fluoride release similar to conventional and resin modified Glass ionomer• In the first ever paste glass ionomer restorative featuring nano filler technology, the product is designed to be quickly and easily be mixed and dispensed using dispenser.• Eg.- Ketac Nano Light Curing Glass Ionomer Restorative Material.
COMPOMER• This is the term developed by manufacturer with a claim to incorporate with a composite resin• A compomer is a composite resin that was an ionomer glass which is the major constituents of a glass ionomer as the filler.• There is also a small quantity of a dehydrated polyalkenoic acid incorporated with the filler particles.• The filler particles are held within an anhydrous resin matrix and there is complete absence of water.• Hence there can be no ion exchange, acid/base setting reaction and material remains inert.
COMPOMER• The setting reaction is lightly activated and there has been a degree of water uptake into the restoration.• a composite resin that was an ionomer glass which is the major constituents of a glass ionomer as the filler.• There is also a small quantity of a dehydrated polyalkenoic acid incorporated with the filler particles.• The filler particles are held within an anhydrous resin matrix and there is complete absence of water.• Hence there can be no ion exchange, acid/base setting reaction and material remains inert.• The setting reaction is lightly activated and there has been a degree of water uptake into the restoration.
COMPOMER• After water uptake there will be an ion exchange between the glass and the rehydrated polyalkenoic acid followed by a low grade fluoride release , but this will not be sustained at a higher level.• Since Fluoride uptake cannot take place a compomer cannot be regarded as a fluoride reservoir.• The most significant difference between the two materials is the absence of ion exchange adhesion.• The adhesive system used with a compomer is based on the acid etch resin bond system found with all composite resins• The %age of filler content is relatively low compared to hybrid composite resins. However ,both water uptake and wear factor are relatively high.
CERAMIC REINFORCED GLASS IOMOMER• Ceramic reinforced polymer G.I.C. featured stronger compressive , flexural and tensile strength as compared to Amalgam.• The main advantages is its excellent wear characteristics.• Some other features include superior radio-opacity, high level of Fluoride release, good biocompatibility and natural adhesion to tooth structure.• Material is excellent for core build-ups and posterior restorations.• Its available in white and a universal tooth shade.• Also , water mix and powder/liquid versions are available.• This material was mainly designed to match the strength and durability of amalgam . The presently available ceramic reinforced G.I.C. includes Amalgomer-CR
SETTING RECTION OF RESIN MODIFIED GLASS IONOMERThe setting reaction of resin modified glass ionomeris similar to the acid base reaction though at aslightly slower pace.The usual ionomer salt hydrogel will form alongwith a poly HEMA matrix will be stimulated by lightactivation subsequently an oxidation / reductionreaction resin chains so that in the long run theentire restoration will be set . This has beendesignated as , “Tri-cure setting reaction”.
FACTORS AFFECTING SETTING RATE OF R.M.G.I.• Temperature of mixing slab: Lower the temperature of mixing slab , The longer the working time and vice versa.• However the temperature should always be above the dew point• Powder-Liquid ratio-• The higher the powder content the higher the physical properties.• However the care should be taken too ensure that the materials are properly dispensed before mixing.• Setting reaction of compomer.• These are essentially two different systems for initiating polymerizations in a composite resin.• The original material were all chemically activated , however they exhibit an undesirable color shift.• Subsequently, a system for light activation was developed and this has proven to be relatively color stable.• Its also possible to combine the two systems.
STEPS INVOLVED IN CLINICAL PLACEMENT OF GLASS IONOMER CEMENT Shade selection Isolation of tooth , rubber dam is the material of choice. Cavity Preparation – the objective is to remove all caries and unsupported enamel. Minimal extension is the keyword. If the dentin thickness is 0.5-1mm,lining of calcium hydroxide should be placed. Surface prep-The surface smear is removed by pumice wash. The tooth surface is conditioned with 10% polyacrylic acid application for 10-15 seconds ,followed by 30 seconds water rinse.
STEPS INVOLVED IN CLINICAL PLACEMENT OF GLASS IONOMER CEMENT Cement is mixed according to the manufacturer instructions It should be mixed rapidly to gain working time and should not be more than 45-60 seconds. The tooth should be isolated all through. Place matrix wherever possible and fill the cavity with G.I.C. Remove the matrix and immediately protect it with waterproof material like varnish or Vaseline. Trim the excess with scalpel, Rotary cutting instruments should be used.
STEPS INVOLVED IN CLINICAL PLACEMENT OF GLASS IONOMER CEMENTAfter the removal of excess material a layer ofprotective material a layer of protective material is reapplied.Finishing and polishing is done after 24 hrs.Re-apply the protective material after finishing andpolishing .
CRITICAL PROCEDURES FOR GLASS IONOMER RESTORATIONSSurface conditioning to remove smear layerP:L ratio must be maintained.Mixing time- not more than 45-60 secs andsurface should be glossy due to polyacid thathas not participated in the reaction which helpsin bonding.
CRITICAL PROCEDURES FOR GLASS IONOMER RESTORATIONSPlacement of material-with plastic instrument or injected.Mixed material should be used within 5 minutes.Surface finishing-Delayed for 24 hrs.MODIFICATIONS OF GLASS IONOMER CEMENTIts done to improve strength, fracture toughness and resistantto wear.SILVER ALLOY ADMIX-Mixing spherical amalgam alloy powderwith Type-I glass ionomer.B.CERMET FUSING GLASS POWDER TO SILVER PARTICLES.C.RESIN MODIFIED G.I.C.- to overcome moisture sensitivity andlow early strength.Also, called as Light cured , Dual cured (LC and Acid BaseReaction) , Tricure (dual cure and chemical cure) resin ionomercompomers or hybrid ionomers.
COMPOSITION OF RESIN MODIFIED G.I.C. Powder-Ion leachable glass Initiator for light or chemical cure or both. Liquid-Water Polyacrylic acid/Polyacrylic acid with carboxylic group modified with methacrylate and Hydroxy ethyl meth acrylate monomer.
SETTING REACTION OF RESIN MODIFIED GLASS IONOMER CEMENTPhysical PropertiesThe difference is due to presence of polymerized resinand less amount of water and carboxylic acid in liquid.Tensile strength is higher than that of conventionalG.I.C.Greater amount of plastic deformation.
SETTING REACTION OF RESIN MODIFIED GLASS IONOMER CEMENTBonding similar to conventional G.I.C.Higher bond strength compared to compositeresin.Greater degree of shrinkage due topolymerization, lower water and carboxyliccontent.Reduced water sensitivity.Transient temperature increase duringpolymerization.
ADVANTAGES AND USES OF GLASS IONOMER CEMENT•Extended working time•Improved physical properties•More resistant to dehydration and cracking.•It is a tooth colored material.•It will adhere directly to both enamel and dentinthrough an ion exchange method.•Its biologically active, as its capable of releasingfluoride , calcium and phosphate ions.
DISADVANTAGES OF GLASS IONOMER CEMENT•Its physical properties are not sufficient towithstand heavy occlusal load in large restorations.•Resistance to fracture is one of the main limitationto the use of G.I.C.. Its generally quite satisfactoryfor one surface lesion , but a two surface lesion isalways at risk.•Resistance to fracture also depends on the particlesize of the powder and particle size distribution.
DISADVANTAGES OF GLASS IONOMER CEMENT Improvement in enhancement of strength of G.I.C. can only be of chemical origin or through of microporosities. Resistance to abrasion and wear is a little less than that of a composite resin. They also remain susceptible to dehydration throughout the lifespan, so patients with a dry mouth, should not have their teeth restored with glass ionomer.
COMPOSITE RESINSComposite Resins were developed by R.L.BOWEN.Since epoxy reins have some disadvantages orshortcomings like slow cure and some tendency todiscolor, So , He combined the advantages of epoxy resinsand acrylic resins leading to the development of BIS-GMAmolecule . It has an aromatic ester of Dimethacrylate withepoxy resin as the backbone and acrylic as the functionalreactive group.Composite Resins are the only restorative material otherthan glass ionomer cement ,to that has the ability torestore esthetics and to develop and maintain adhesion inoral environment.
CLASSIFICATION OF COMPOSITE RESINSClassification Based on Filler Particle Size:Megafillers >100 microns (megafilI)Macrofillers =10-100 microns(macrofill)Midfillers =1-10 micron (microfill)Minifillers =0.1-1 micron (minifill)Microfillers =0.01-0.1 micron (microfill)Nanofillers =0.05-0.01 microns( Nanofill)Picofillers =0.005 microns
CLASSIFICATION OF COMPOSITE RESINSCLASSIFICATION BASED UPON MASS PARTICLES SIZE OFTHE MAJOR FILLER1.Conventional=8-12 micron meter2.Small Particle=1-5 micron meter3.Microfilled=0.04-0.4micron meter4.Hybrid=0.1-1.0micron meter.
CLASSIFICATION OF COMPOSITE RESINSClassification based upon the method of polymerizationSelf cureLight curedComposition Of composite materialsResin Matrix : BIS-GMA is the most commonly used resin followed by UrethaneDimethacrylateDiluent monomer like methyl methacrylate monomer or Dimethacrylate monomerssuch as : TEGDMA(TRIETHYL GLYCOL DIMETHACRYLATE),are used to attain higher fillerlevels and to produce pastes of clinically usable consistencies.TEGDMA allows extensive cross linking to occur between chains resulting in a matrixthat is more resistant to solvents , but also increase the polymerisation shrinkage.Filler Particle: Improves the properties of the matrix material.Reduces polymerization shrinkage, Reduces polymerization ,shrinkage, Reduces watersorption and coefficient of thermal expansion.
Composition Of composite materialsImproves Tensile strength , compressive strength andmodulus of elasticity and abrasion resistance.Materials used as fillers are-Colloidal silica ,Quartz ,Barium ,Strontium ,Zirconium .
Composition Of composite materials : Materials used as fillersQUARTZ It has been extensively used as filler in particularly inconventional composites.Advantages : Its chemically inert but its so hard that its difficultto polish and may abrade opposing teeth are restoration.Other materials are not as stable as quartz and may leach outinto aqueous medium.Translucency of the filler must be similar to that of toothstructure and its index of refraction must closely match that ofresin.For BIS-GMA+TEGDMA combination refractive index is about 1.5Most of the glass or quartz that are used as fillers have R.I. of1.5
Composition Of composite materialsCoupling Agent It provides a bond between the resin matrix and fillers ,thus improving the physical and mechanical propertiesand providing stability by preventing water frompenetrating along the resin filler interface.Eg. - Organosilanes are commonly used1) Titanates2) ZirconatesINHIBITORSHydroquinones butylated hydroxytoluene (<0.01%)Minimizes or prevents spontaneous polymerization . Itreacts with free radicals if formed.
Composition Of composite materialsUV AbsorbersTo improve color stabilityEg - 2-Hydroxy-4-Methoxy BenzophenolsActivatorsFor self cure-Tertiary amineFor Light Cure-LightInitiatorsSelf Cure- Benzoyl Peroxide ,Light CURE-Alpha diketones like camphor quinones,UV light- Benzoin Methyl Ether,Pigments
PROPERTIES OF COMPOSITE RESINS•Linear coefficient of thermal expansion is twice asmuch as the value of Amalgam and 3-4 times greaterthan that for tooth structures.•Most composites can be practically cured only tolevels of 55-65% conversion of monomer sites.Usually due to inadequate curing energy from visiblelight cure unit and is improved by post curing.
PROPERTIES OF COMPOSITE RESINS•Water absorption swells the polymer portion and promotes diffusion anddesorption of any unbound monomer . Water plasticizes the composite andchemically degrades the matrix into the monomer . Increased filler contentlower is water absorption.•Microfill composites are the least wear resistant.•Composite with high matrix content and self cured have more tendency toundergo yellowing . Addition of white light absorbs and antioxidants reducethe chance of yellowing.•Beveling tend to blend any color difference associated with margins andprovide more surface area of bonding.•Good Marginal integrity-•Butt joint margin wear slowly but create a meniscus appearance againstenamel . Beveling produces thinner ledges of material that are prone tofracture.•Biocompatible, but unemployed materials are potentially cytotoxic. They arevery poorly soluble in water and are polymerized into a bound state beforedissolution or diffusion.
PROPERTIES OF COMPOSITE RESINS•Compared to unfilled resins ,filled resins are morestronger ,increased modulus of elasticity(increasedmodulus of elasticity= less is the flexibility and viceversa) , good abrasion resistance and lower coefficientof thermal expansion.
CLINICAL STEPS• 1)Etching and Bonding• 2)Delivery and Placement• 3)Incremental Build Up• 4)Depth of cure
CLINICAL STEPS - Etching & BondingAn essential pre-requisite for the micro-mechanical attachmentis that the enamel should be etched with 37% Orthophosphoricacid. To demineralize the enamel to a depth of 20-30 mm andrender it porous.A very low viscosity unfilled resin is then flowed over the surfaceand allowed to soak into the porosities for about 30 secs. beforeits light activated . Composite resin is then built over resin bond.Pre-Requisite for etchingFirst the enamel at the cavity margins must be fully mineralizedand based on healthy dentin.There must be no crack on the tooth.Best union will be at the ends of enamel rods rather than alongthe long sides , so its desirable to develop a reasonably longbevel at the cavosurface margin
CLINICAL STEPS - Etching & BondingIn juvenile enamel there is less mineral or more organiccollagen. There will be more water present because ofthe presence of dentinal tubules and their direct accessto pulp and the amount of fluid and their direct accessto pulp and the amount of pulp and the amount of fluidflow will only be enhanced following acid etchingbecause it will lead to opening and funneling of tubulesEven a small cavity will be relatively close to pulp andtherefore there will be a greater density of tubules onthe floor of cavity and a relatively greater fluid flow.
CLINICAL STEPS - Etching & Bonding The goal of resin dentin bonding agent isto attach composite resins to healthy dentin andto seal the dentinal tubules against the entry ofbacteria and their toxins.This will avoid post restoration sensitively cariesand loss of restoration.Its possible to demineralize some of the dentin.
CLINICAL STEPS - Etching & BondingPRINCIPLES TO SUCCESSFUL RESIN DENTIN BONDINGDentin should be etched to remove smear layer anddentin tubule plugsEtching should be sufficient to demonstrate thesurface layer of intertubular and intratubular dentinleaving collagen fibers exposed and available for amechanical interlock with resin.Surface should be washed thoroughly to remove allremaining etchant.
CLINICAL STEPS - Etching & BondingSurface should remain wet but not flooded.Apply a hydrophilic primer containing acetoneor similar to guide and facilitate penetration ofresin adhesive around the exposed collagenfiber.Finally apply the resin adhesive and cure beforeapplying composite resins.
CLINICAL STEPS : Delivery &PlacementChemical cure and the dual core materials will bepackaged as a paste /paste system or a powder /liquid system.To ensure proper adaptation to the cavity floor ,itsdesirable to place the freshly mixed material into thedisposable syringe and then temp the material intothe cavity with a small plastic sponge .Light activated materials will always be delivered inlight proof carpules or which have been loaded undervacuum. This means they are free of porosity at thetime of delivery.
CLINICAL STEPS : Delivery and placementPlacement must be undertaken with care and attentionto detail with particular reference to the depth of cureavailable through a curing light , by checking periodicallyto ensure that lower layers are also cured adequately.INCREMENTAL BUILD UPDue to problems posed by light activation of compositeresins , its essential to any restoration deeper than thatabout 2.0mm.Incremental placement means placement of thecomposite in small quantity in selected areas of thecavity and then directing the light activating unit in sucha way that while curing the resin will shrink towards thetooth structure rather than away from it.
CLINICAL STEPS : Delivery and placement• Its recommended that increments be as small as possible . The activator be applied from many positions during Buildup.• DEPTH OF CURE• In a child , its imperative that the activator light be placed within 1-2mm of the surface of the newly placed restoration , otherwise the depth of cure will be limited.• Factors to be considered while curing• The degree of cure will decrease with increased depth of cure, greater the translucency deeper the cure.• Light activator units vary in their light output over time as well as with power fluctuations.
CLINICAL STEPS : Delivery and placement• Tip of the light source should be placed as close as possible to the restoration and should never be more than 4mm away.• The depth of cure should be measured from the face of the activator light.• Curing through tooth structure will reduce the depth of cure to the same extent as if curing through a composite resin of similar opacity.LIMITATIONS OF COMPOSITE RESINS• Both resins and fillers are used anhydrous and completely inert .However ,some of the minor constituents such as HEMA , have been identifiable in thepulp tissue in certain mer chain may be an irritant to the pulp in circumstancesand care should be exercised in its use.• Any unreacted polymer chain may be an irritant to the pulp and lead to postinsertion sensitivity.• The tissue cells respond less favorably to composite resins then do to glassionomer and it has been postulated that incomplete cure of resin is the primecause of this.
CLINICAL STEPS : Delivery and placementCLINICAL CONSIDERATIONS• IN Pediatric dentistry , a restoration will not be expected to last for more than few years , so a limited amount of wear an be tolerated.• However , a relatively large setting shrinkage will be undesirable.• Esthetics and fracture resistance will not be of great significance but the ability to bond effectively to both the enamel and dentin will not be relevant• A relatively shorter concentration span from the patient as well as limited access to oral cavity , to simplicity of placement technique will be important
CLINICAL STEPS : Delivery and placement• The operator must be aware of the relevant properties of both composite resins and G.I.C. , so that a logical decision regarding use can be made.
Amalgam• Silver Amalgam restorative material is obtained by the trituration of Amalgam alloy with mercury.• It’s the most reliable and inexpensive dental restorative material of all.
TYPES OF DENTAL AMALGAM ALLOYSBased On the content:• High Copper alloy : copper content more than 12%• Low copper alloy : copper containing less than 6%• Gallium alloy
TYPES OF DENTAL AMALGAM ALLOYSBased on particle shape and type• Lathe cut: Irregularly shaped filings produced by cutting an ingot of alloy on a lathe.• Spherical particles: Produced by atomizing the alloy whilst still liquid into a stream of inert gas.Based on Zinc content• Zinc containing :Alloys with more than 0.01% Zinc• Zinc free: Alloys with less than 0.01% Zinc
TYPES OF DENTAL AMALGAM ALLOYSBased on Gamma2 content• Amalgams may be classified as gamma 2 containing or gamma2 free• A) low cu amalgam contain the Sn-Hg phase which is called Gamma2 phase to distinguish it from gamma2 phase of silver tin and silver mercury alloy systems.• B)Within several hours after amalgamation all correctly manipulated High cu amalgams are gamma2 free.
TYPES OF DENTAL AMALGAM ALLOYSAccording to size• Fine cut (particle size is 36 micron)• Micro cut(particle size is 26 micron)According to the method of dispensing• As powder and liquid• As a capsule• As pellets or pills of alloy powder(3% of the Hg is mixed with the alloy powder and this facilitates faster reaction)
PROPERTIES OF AMALGAM• Increased mercury – leads to increased expansion , creep and corrosion.• Compressive strength-Admixed is 430 Mpa after 7 days• Tensile strength-Admixed is 50MPa after 24 hrs.• Surface hardness – 3-8 mins.• Setting Time-5-10 mins.• Increased expansion is due to increased mercury ,short trituration , low condensation pressure and water contamination.• Creep is associated with increased or decreased trituration , time lags between trituration and condensation , increased mercury , less condensation force.
Criterion for selection of Amalgam Alloy• Small particles are selected ; Better strength, easy to carve ,good surface finish , good marginal adaptation , poor corrosion resistance.• Spherical is selected: Better strength , easy to curve , good finish , good marginal adaptation , good corrosion resistance and easy condensation (Lathe cut resists condensation, may result in poor corrosion resistance , porous restoration with rough surface and poor marginal adaptation).
Criterion for selection of Amalgam Alloy• High copper is preferred : Better strength less creep , good corrosion resistance due to absence of alpha2 phase. DRAWBACKS OF SILVER AMALGAM• Good conduction of Heat(Requires good insulation).• Poor marginal adaptation : so varnish is applied.• Poor esthetics
DRAWBACKS OF SILVER AMALGAM• Poor modulus of elasticity , proportional limit, and tensile strength.• Electrolyte corrosion• Poor adhesion to tooth structure.• Ditched amalgam
CONDENSATION AND CARVING OF SILVER AMALGAM• Amalgam alloy and mercury is dispensed and mixed as per the manufacturer’s instructions• Material is loaded into the amalgam carrier• Proximal box is first filled in a class II cavity• In other cavities its started from one side slowly moving and filling the entire cavity• The material is firmly condensed into the cavity.• Amalgam is condensed using condensers.• Initial condenser should be small enough to condense the material into the line angles.• Each condensing stroke should be small enough to condense the material into the line angles.• Each condensing stroke should overlap the previous condensing stroke to ensure that entire mass is well condensed• Cavity is overfilled and condensed with a large condenser.• Parallelogram condenser is used to condense narrow occlusal cavity.
CONDENSATION AND CARVING OF SILVER AMALGAM• This is followed by pre-carve burnishing of the amalgam . Its form of condensation done with a large ball burnisher , using heavy strokes mesiodistally and faciolingually . This helps to remove all she excess Amalgam and blends the restorative material with cavity margins.• Initial gross carving of the restoration is done followed by fine carving of cuspal inclines , triangular fossa and grooves . Hollenbeck , wards or diamond amalgam carvers are used for the purpose of carving amalgam• Wedges and matrix placed can be removed after initial carving• Post carve burnishing is done using a ball burnisher : It involves the light rubbing of the carved surface to improve smoothness and produces satin appearance.(not a shiny).insertion.• Finishing and polishing is done after 24 hrs of insertion.
CONDENSATION AND CARVING OF SILVER AMALGAM• Mercury Hygiene - Precautions that should be taken regarding the mercury exposure in dental office staff and the patients are:• When removing an old amalgam restoration rubber dam should be in place and high vacuum evacuation should be used . Glasses and disposable free masks are worn• Amalgam capsules should be preferred to the conventional dispensing• Closed amalgamator should be used• Free mercury and amalgam scraps should be stored in an unbreakable tightly closed container away from any source of heat preferably in water.• Since, mercury vaporizes at room temperature operatories should be well ventilated to minimize the mercury level in air.• Its necessary to place a lining material on the floor of the cavity prior to placement of final restoration.
LINING MATERIALSMATERIALS USED IN PAST ANDREASONS FOR USE1)ZINC PHOSPHATE CEMENT• This was used extensively may years ago on the theory that it was strong enough to accept the load imparted to the dentin by condensation of an amalgam restoration.• It was accepted that there was no therapeutic value in this material and in fact , it has shown to be mildly irritating if placed close to the pulp.• Its outdated in the present.
LINING MATERIALS : MATERIALS USED IN PAST AND REASONS FOR USE2) ZINC OXIDE EUGENOLThis became popular because of the antibacterial property ofEugenol as well as the sedative effectiveness of Zinc oxide• Its used a s a temporary sedative dressing over a large cavity with a n inflamed pulp.• Its effective as it provides a seal around the periphery of a cavity as a bacteria can not penetrate through Eugenol.• Fast setting type were developed to allow this to be used alone as a lining but as its relatively weak , it does not offer support for an amalgam restoration placed over the top.
LINING MATERIALS : MATERIALS USED IN PAST AND REASONS FOR USERECENT MODIFICATION• Embonte Zinc Oxidizing Eugenol Temporary Cement which is conveniently packaged in an Auto mix delivery system.• This is engineered with pure essential oil extracts.• Creamy consistency of Embonte Auto mix allows easy application from static mixing tip to crown.
LINING MATERIALS : MATERIALS USED IN PAST AND REASONS FOR USE3) CALCIUM HYDROXIDE• Used as a liner because of its antibacterial property as well as because of the theory that the excess calcium ions present in the cement would be available to the pulp and would encourage remineralization within the pulp chamber.• Its very alkaline with a pH 13 ensures the fact that its very presence will make the bacteria unable to thrive and help in stabilizing conditions on the floor of the cavity.
LINING MATERIALS : MATERIALS USED IN PAST AND REASONS FOR USE• If placed to close necrosis of the subjacent soft tissue , but in the absence of bacteria the pulp is likely to survive beyond the necrotic area.• It will then lay down a calcific barrier a short distance away and it was assumed that it was calcium ions from the lining which promoted the repair.4 ) GLASS IONOMERThis is now a material of choice for lining the cavity because itsan effective barrier to temperature change and also – Galliumalloy : A mercury free metallic substitute to silver amalgam ,provides barrier to temperature change and also provides ionexchange adhesion that is most effective barrier to microleakage of bacteria under a restoration
RECENT ADVANCEMENTS INRESTORATIVE MATERIALS USED IN PEDIATRIC DENTISTRY1) ALTERNATIVE TO AMALGAM-• In view of hazards of mercury present in amalgam a mercury free alloy has been suggested .• Eg. - Gallium alloy : A mercury free metallic substitute to silver amalgam
RECENT ADVANCEMENTS IN RESTORATIVEMATERIALS USED IN PEDIATRIC DENTISTRY2) RECENT ADVANCEMENTS IN FIELD OFCOMPOSITE RESIN RESTORATIVE MATERIALA) Dentil flow- Its a new flowable composite havingacceptable shear bond strength for bonding orthodonticbracket , when used with an intermediate unfilled lowviscosity resin.B) Packable composites - Its obtained by varying particlesize and size distribution through the water uptake andwear factor will remain standard and acceptable .Material is less sticky
RECENT ADVANCEMENTS IN FIELD OF COMPOSITE RESIN RESTORATIVE MATERIALC) TETRIC EVOFLOW -It’s the new nano optimizedflowable composite form.• Ivoclar vivadent and successor product of Tetric flow• Characterized by optimum surface affinity.• Penetrates even into areas that are difficult to reach.
RECENT ADVANCEMENTS IN RESTORATIVE MATERIALS USED IN PEDIATRIC DENTISTRY3) RECENT ADDITIONS IN G.I.C.a) Interval II Plus- Interval II Plus is a dependable , onecomponent , ready mixed , temporary filling materialwith glass ionomer and leachable fluoride.• With no ZnO /Eugenol , Its safe on resin based materials.
RECENT ADVANCEMENTS IN RESTORATIVE MATERIALS USED IN PEDIATRIC DENTISTRY4) SMART MATERIALS -These materials though notavailable commercially , retain the potential toreplace currently used ones• These have been termed as ,”SMART”, as they are consistent with the newer generation of materials that support the remaining tooth structure with cavity preparation done in a conservative manner.• Some of these materials are biomimetic in nature wherein there may be properties that mimic natural tooth substance such as enamel and dentin better.
Ariston pHc restoration of tooth 24, class II, DO cavity (image in a mirror) 12 months after the filling placement. No signs of marginal leakage or fracture.
SMART MATERIALS IN DENTISTRY CAN BE CLASSIFIED ASRESTORATIVE DENTISTRY TYPESA. Passive Smart Restorative Material Glass Ionomer Cement Resin Modified Glass Ionomer Cement Compomer Dental CompositeB. Active Smart Restorative Material Smart Composites Ariston pHC ACP CompositesC. Prosthetic Dentistry Smart Ceramics Smart Impression Material
SMART MATERIALS IN DENTISTRY CAN BE CLASSIFIED ASD. Prosthetic Dentistry Shape Memory AlloyE. Preventive Dentistry Fluoride releasing pits and fissures sealantsF. Endodontics Niti Rotary instruments
BRIEF INTRODUCTION : ACTIVE SMART MATERIALS1) AMORPHOUS CALCIUM PHOSPHATE-ACP: it’s avital antecedent in the biological formation ofhydroxyapatite .ACP has two properties :PreventiveRestorativeDue to the above mentioned properties its used indental cements and adhesives pits and fissuresealants and composites.
BRIEF INTRODUCTION : ACTIVE SMART MATERIALS2) Ariston Phc : Alkaline Glass Restorative Material3) Ivoclar – Vivadent (Liechenstien), introduced amaterial in 1998 , Ariston pHC (pH control),which isclaimed to release fluoride , hydroxide and calciumions , when the pH in restorations of this materialfalls to the critical Ph.• This is said to neutralize acid and counteract the decalcification of enamel and dentin.
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pedodontics,restorative materials,restorative materials used in paediatric dentistry