Restorative Materials In Pediatric Patients

RESTORATIVE MATERIALS IN PEDIATRIC PATIENTS Submitted by : Dushyant Chopra Varsha Bihani B.D.S final prof.

INTRODUCTION At least 1/3rd of the current dental research effort is directly concerned with the development of better materials and improved techniques for their manipulation. The oral cavity is a formidable obstacle to the maintenance of the integrity of the tooth structure and the materials used in its restoration or replacement. Biting stress on the cusp of the molar tooth may be as great as 207MPa. The pH of dental plaque, food and beverages fluctuates daily from ranges of low acidity to high alkalinity.The temperature during the course of a normal meal may vary as much as 150*F. The warm , moist oral cavity contains a variety of enzymes and debris providing optimum conditions for the accumulation of surface deposits that can tarnish or corrode metallic restorations. For these and other reasons restorative materials are readily subject to fracture, solubility, dimensional change and discoloration.

CLASSIFICATION 

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METALLIC RESTORATION Silver amalgam TOOTH COLORED Glass Ionomer Cement Composites Silicate cement TEMPORARY RESTORATIVE MATERIALS Zinc Oxide Eugenol Zinc Polycarboxylate BASES AND LINERS Calcium Hydroxide Zinc Phosphate Glass Ionomer Cement

SILVER AMALGAM

Introduction Amalgam is a special type of alloy that contains mercury as one of its constituents. Dental amalgam is an alloy made by mixing mercury with a silver-tin alloy powder. It is most common material used for class 1 and class 2 cavities.

COMPOSITION 

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Ag(68.5%) - It whitens the alloy and increases the strength. Sn(25.5%) - It controls the reaction b/w Ag and Hg and reduces strength and resistance to corrosion. Cu(5%) - It increases strength and hardness. Zn(1%) - It acts as deoxidizer and causes delayed expansion. Pt and Pd – It hardens the alloy. Hg is added to produce rapid reaction.

Classificatio n

DEPENDING ON ALLOY PARTICLE SIZE AND SHAPE Lathe cut alloys  Spherical alloys  Admixed alloys 

DEPENDING ON COPPER/ZINC CONTENT Low copper (contains Cu upto 2-5%)  High copper (contains Cu upto 13%)  Zinc containing  Zinc free 

Depending on addition of nobel metal  

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1ST generation: 3 parts Ag + 1 part Sn 2nd generation: Original alloy + Cu upto 4%+ Zn upto 1% 3rd generation: Ag-Cu eutectic alloy 4th generation: Alloying of Cu + Ag + Sn upto 29% 5th generation: Pd + Ag + Cu

Manipulation 

Proportioning: Recommended alloy: mercury ratio is 5:7or 5:8.In EAMES Technique equal parts by wt of alloy and mercury is taken.

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Trituration: It’s the mixing of silver alloy with mercury -Mechanical mixing -Hand mixing by mortar and pastel Ideal mixing time is 1 min.

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Mulling: It is done by pressing the squeezed mix in a piece of rubber dam material to produce homogenous mass.

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Condensation: In this mixed material is packed in to the cavity in increments. A load of 4-5 kg is applied to increment.

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Burnishing: It is continuation of condensation done by using round burnisher and moving it over condensed amalgam from restoration towards tooth surface so improving marginal adaptation.

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Carving: It is anatomical sculputuring of amalgam material to produce a restoration functional, non interfering occlusal anatomy

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Finishing and polishing

PROPERTIES 

Strength: Compressive strength of high Cu amalgam are higher than low Cu amalgams

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Creep: According to ADA specification no.1,amalgam must have a maximum of 5%creep

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Hardness: It is similar to that of tooth structure

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Dimensional stability: According to ADA specification no.1 expansion or contraction should not be more than 20 microns/sqcm

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Galvanism: When in contact with dissimilar metal an electrostatic discharge is generated and patient feels pain.

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Thermal Conductivity: High

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Tarnish and corrosion: High Cu show less tarnish and corrosion than low Cu

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Marginal Leakage: Decreases with time.

MERCURY TOXICITY Mercury poisoning (also known as mercurialism, hydrargyria, Hunter-Russell syndrome, or acrodynia when affecting children) is a disease caused by exposure to mercury or its toxic compounds. Mercury is a cumulative heavy metal poison which occurs in its elemental form, inorganically as salts, or organically as organomercury compounds; the three groups vary in effects due to differences in their absorption and metabolism, among other factors. However, with sufficient exposure all mercury-based toxic compounds damage the central nervous system and other organs or organ systems such as the liver or gastrointestinal tract. Symptoms typically include sensory impairment (vision, hearing, speech), disturbed sensation and a lack of coordination. The type and degree of symptoms exhibited depend upon the individual toxin, the dose, and the method and duration of exposure. Due to its toxicity, there have been campaigns in many countries to ban mercury altogether.

PREVENTIVE MEASURES Capsules used with amalgamator should have a tight fitting cap.  When inserted into cavity mixture has not fully reacted. High volume evacuation should be used to prevent vapors from diffusing.  Polishing should be done at slow speed.  Left out material should be stored in tight sealed container. 

Advantages of amalgam restoration. Reasonably easy to insert.  Maintain anatomic form well  Resistance to fracture.  Long service life.  Cheap  Not overly technique sensitive.  After a period of time prevents marginal leakage. 

Disadvantages of amalgam restoration. The color does not match tooth structure.  They are subject to corrosion and galvanic action.  Risk of mercury toxicity  They eventually show marginal breakdown.  They do not bond to the tooth structure. 

GLASS IONOMER CEMENT

INTRODUCTION Developed by McLean, Wilson and Kent in 1971. It is a salt formed by reaction between polyalkenoic acid and calcium-alumino-fluorosilicate glass. It offers true chemical bond to enamel and dentin.

Classification 1 ) Traditional Glass Ionomer : Type I: Luting cement. Type II: Restorative cement. Type III : Liners & Bases. 2) Metal modified Glass Ionomer : a)Miracle Mix . b)Cermet cement. 3 ) Light cure Glass Ionomer : HEMA added to liquid 4 ) Resin modified Glass ionomers / Hybrid Glass ionomers Composite resin in which fillers substituted with glass ionomer particles. Pre cured glasses blended into composites.

Classification according to application  

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Type I: Luting agent. Type II: Restorative cements. Type II a : Aesthetic filling materials Type II b: Reinforced materials ( Fuji IX ,Fuji II LC ) Type III : Lining cements. Type IV : Fissure sealent. Type V : Orthodontic cements. Type VI : Core build up cements.

COMPOSITION POWDER      

SiO2 Al2O3 AlF3 CaF2 NaF Al2 (PO4)3

35-40% 20-25% 1.5-3% 15-20% 4-10% 4-15%

LIQUID 

Polyacrylic acid in the form of copolymer with itaconic,maleic and tricarballylic acid. Acid increases the reactivity and decreases viscosity.

Compomers It is a combination of composites (the “comp” in their name) and glass ionomers (“omer”). These materials have two main constituents: dimethacrylate monomer with two carboxylic groups present in their structure, and filler that is similar to the ion-leachable glass present in GICs. There is no water in the composition of these materials, and the ion-leachable glass is partially silanized to ensure some bonding with the matrix. These materials set via a free radical polymerization reaction, do not have the ability to bond to hard tooth tissues and have significantly lower levels of fluoride release than GICs.

Miracle Mix

Restore-pf vic

tgrestoglass

Fuji IX gp

Ketac-cem

Composites

Introduction These properties make them superior to silicates but high polymerization shrinkage and high coefficient of thermal expansion lead to clinical deficiencies and premature failure. To resolve these deficiencies, inert filler particles are added to reduce the volume of resinous component. The incomplete filler resin bond leads to defects between mechanically retained filler particles and the surrounding resin. These defective areas stain because of fluid leakage and surface appearance of restorations is often unacceptable. A new type of composite was then introduced by Bowen. He used BISGMA and dimethacrylate resin. Silane was then used to coat filler particles that could bond chemically to the resin.

CLASSIFICATION Based on curing mechanism  

Chemically activated Light activated

Based on size of filler particle    

Conventional Small particle Microfilled Hybrid

8-12 um 1-5 um 0.04-0.4 um 0.6-1.0 um

Components   

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Resin matrix Inorganic filler particle Coupling agents (silane) to provide bond between inorganic filler particles and resin matrix Activator initiator system to polymerize the resin Additives to improve colour stability Pigments to achieve an acceptable match to colour of tooth structure

Resin Matrix Most dental composite materials use monomers that are aromatic or aliphatic diacrylates  Most commonly used dimethacrylates  BISGMA  Tegdma  Uedma 

Filler Particles They improve the properties of matrix materials. Since less resin is present in a composite the polymerization shrinkage is reduced as compared with unfilled resins. Shrinkage varies with product and is on the order of 3% vol at 24 hrs As compared with unfilled resins, filled resins have following properties: Reduces: Polymerization shrinkage Water sorption Coefficient of thermal expansion Improves: Mechanical properties Compressive strength Tensile strength Modulus of elasticity Abrasion resistance

Coupling Agents #Provides bond between 2 phases of composites *Uses  To bind filler particles to resin matrix  More flexible polymer matrix to transfer stresses to the filler particles  Provide hydrolytic stability by preventing water from penetrating along filler resin interface  Improves physical and mechanical properties *Various coupling agents  Zirconates  Organosilanes-most commonly used  The hydrolysed silane molecule contains silanol grps and carbonyl grps.hydrogen bonds develop between these grps and hydroxyl grps of silica.this leads to expulsion of water.

Activator initiator system 

Chemically activated resins a. benzoyl peroxide(initiator) b. tertiary amine(activator) When two pastes are spatulated, free radicals are generated when benzoyl peroxide reacts with tertiary amine and addition polymerization is initiated. Used for build ups that are not readily cured with light source.

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Light activated resins-1 paste containing a. Photoinitiator(camphoroquinone)which has absorption range between 400-500 nm (blue region). b. Amine accelerator(dimethyl 1 aminoethyl methacrylate) When these compounds are left unexposed in this paste they do not react however exposure to light of correct wavelenghth 468nm produces an excited state of photoinitiator & an interaction with amine resulting in formation of free radicals that course addition polymerization reactions.

INHIBITORS Are added to prevent spontaneous polymerization of monomers. Butylated hydroxytoluene used in conc. of 0.01 wt%. Mechanism of action: If a free radical has been formed by a brief exposure to light when material was dispensed the inhibitor reacts with the free radical. This inhibits chain propagation by terminating the ability of the free radical to initiate polymerization process. When all inhibitors have been consumed chain propagation will occur.

Indications # # # # # # # # # # #

Classes I, II, IV, V, VI restoration Foundations or core buildups Sealants and conservative composite restorations Esthetic enhancement procedures Partial veneers Full veneers Tooth contour modifications Diastema closures Cements Temporary restorations Periodontal splinting

Contraindications   

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Patients who do not maintain oral hygiene. Uncooperative patients. Teeth broken down to the extent that inadequate tooth tissues remain to create adequate resistance and retention forms for the purposes of bonding. Teeth in which outline form includes marked undercuts. Teeth which show excessive wear. Situations where moisture control for appropriate bonding of inlays and onlays cannot be secured and maintained. Teeth that experience heavy occlusal forces like in bruxism, clenching etc. Teeth in which there are deep gingival margins that have insufficient enamel for bonding.

3M Filtek P60

Heliomolar HB

Bright Light

C-Fill MH

PRODIGY condensar

CALCIUM HYDROXIDE

Introduction Calcium hydroxide is mainly used as pulp protecting agent. It is used as liners in deep cavities. It provides pulp protection in preparations very close to pulp. It performs two main functions :1) Sedation of existing pulpal inflammation. 2) Prevention of further irritation by sudden temperature change.

AVAILABLE AS 2 paste system containing base and catalyst paste in collapsible tubes.  Light cured system.  Single paste in syringe form.  Powder form mixed with distilled water. 

Composition BASE PASTE: 1) Glycol Salicylate 40% 2) CaSO4 3) Titanium dioxide 4) Calcium tungstate or BaSO4 CATALYST PASTE: 1) Ca (OH)2 50% 2) ZnO 10% 3) Zinc Stearate 0.5% 4) Ethylene toluene 5) Sulfonamide 39.5%

PROPERTIES 

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Poor mechanical property but better than zinc oxide eugenol. Compressive strength is 10 to 27 MPa after 24 hr. strength continue to increase with time. Tensile strength is 1 MPa. If used in thick layer provide good thermal insulation. High solubility and increases when exposed to pgospheric acid and esters. It is highly alkaline and kills bacteria by breakdown of proteins.

MANIPULATION Equal length of two pastes are dispensed on a paper and mixed to a uniform color. Material carried and applied using an applicator.

SETTING REACTION Calcium hydroxide reacts with salicylate ester to form chelate i.e. calcium disalicylate.

SETTING TIME 2.5 to 5.5 mins. Reaction is accelerated by moisture therefore sets faster in cavity.

USES  

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Cavity liner :- It helps in formation of reparative dentine and used in deep cavity preparations. Pulp capping :- It is an excellent dressing for exposed pulp for maintaining the pulp vitality due to formation of secondary dentine. Root canal filling :- It is used as intra-canal medicaments for killing bacteria in root canal. But rarely used in primary dentition. Perforation repair :- It causes hemostasis so used for controlling bleeding in case of perforation. Apexification :- It is defined as process of creating environment within which root canal and periapical tissue after pulp death is formed that allow calcific barrier to form across open apex. Calcium hydroxide is the material of choice. But is is mainly used in young permanent teeth in which root apex is not formed.

Bosworth Hydrox

Pulpdent Paste

PULPDENT Root Canal Sealer

CALCIDOR

ZINC PHOPSHATE CEMENT

Introduction Zinc phosphate cement the one of the oldest and widely used cements, and is commonly used for luting permanent metal restorations and as a base. It is a high-strength cement base, mixed from zinc oxide powder and phosphoric acid liquid. Due to its low initial pH, it may cause pulpal irritation, especially where only a thin layer of dentin exists between the cement and the pulp; thus is especially important to follow the correct procedures and precautions when using zinc phosphate cement.

APPLICATIONS Luting of restoration  High strength base  Temporary restorations  Luting or orthodontic bands and brackets. 

COMPOSITION   

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Powder Zinc oxide – 90.2% Magnesium oxide - 8.2 % Other oxide - 0.2 % Silica - 1.4 %

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Liquid Phosphoric acid – 38.2% Water – 36% Aluminum phosphate – 16.2% Aluminum – 2.5% Zinc – 7.1%

CLASSIFICATION Type I – Fine grained for luting.  Type II – Medium grained for luting and filling. 

MANIPULATION         

Cool glass slab is used. Powder added in increments. Mixing done with stainless steel spatula in circular motion. Large area covered while mixing to dissipate heat. Material inserted immediately. Area should be dry. Powder:liquid ratio -1.4gm/0.5ml SETTING TIME :- 5-9 mins. MIXING TIME :- 1.5 mins.

SETTING REACTION Phosphoric acid attacks the surface of the particle, dissolving zinc oxide and forming zinc phosphate. The aluminium complexes with the phosphoric acid to form zinc aluminophosphate gel. This reaction is exothermic.

PROPERTIES 1) Compressive strength: It gains 75% of its max strength in 1st hour 2) Tensile strength: It is less so making it brittle (5.5 MPa). 3) Modulus of elasticity: Comparatively high so makes it stiff and resistant to elastic deformation (13.5GPa). 4) Solubility and disintegration: In mouth shows more disintegration. Solubility is more in dilute organic acid. 5) Film Thickness: For luting: thickness should be 25microns or less. For filling: thickness should not be more than 40microns. 6) Thermal properties: Good thermal insulator. 7) Adhesion: Mechanical interlocking. 8) Biological properties: At the time of insertion, high acidity ‘coz of phosphoric acid so thin mixes are avoided. 9) Pulp protection: Lining is provided of Zinc oxide eugenol, hydroxide, or varnish.

calcium

Bosworth

ZINC PHOSPHATE CEMENT

tgzincem

Conclusions # GICs are favourable for Class I cavities and in uncooperative children. # Compomers show best long-term performance in primary teeth. The cooperation has to be sufficient, at least during bonding and layering. # The biggest effort is needed for resin composites. After rubber dam application and correct establishment of technique-sensitive adhesion, resin composites reach the level of compomers.