department of cons (3)

DEPARTMENT OF CONSERVATIVE &

ENDODONTIC DENTISTRY

BY,DR. PALAK & DR. NAZIA

2006 BATCH

Introduction

• The main goal of dentistry especially conservative dentistry is to preserve the health of tooth .

• Cavity varnishes ,liners & bases are important materials used as an adjunct to provide additional protection for the health and well-being of a tooth being restored.

Available materials1. Cavity Varnish2. Cavity Liner & Basesa) Calcium hydroxide b) Zinc Oxide Eugenolc) Glass Ionomersd) Resine) Zinc Phosphate (Zinc Oxyphosphate)f) Zinc Polycarboxylate (Zinc Polyacrylate)

CAVITY VARNISHConsidered either a cavity liner, sealer or simply varnish

CAVITY VARNISH

DefinitionA varnish is a natural gum, such as copal or rosin, or a synthetic resin dissolved in an organic solvent such as acetone, chloroform, or ether.

Composition, structure and properties of a typical liner Copal Resin Varnish (Copalite)

COMPONENTSSolid SolventSetting reaction

10% copal resin90% ether, acetone, alcoholPhysical (by solvent evaporation)

STRUCTUREArrangementBondingComposition (phases)Defects

Amorphous filmCovalently bonded organic materialSingle phasePores and cracks

PHYSICAL PROPERTIESThermalElectricalLCTEWetting

InsulatorInsulatorHighPoor on hydrophilic surfaces

CHEMICAL PROPERTIESSolubility (% in water) LowMECHANICAL PROPERTIESTensile strength (MPa)Elongation (%)

< 1< 0.1%

BIOLOGIC PROPERTIESToxicity None, if solvent eliminated safely

CAVITY VARNISHAdvantages Disadvantages•Seals dentinal tubules,•Reduced microleakage,•Reduced postoperative sensitivity•Reduced pulpal irritation•Reduced tooth discoloration associated with amalgam restorations.(amalgam blues)•Low cost•Act as a barrier to protect the tooth from highly acidic cements such as zinc phosphate.(chemical insulator)

•Cannot be used with adhesive materials (glass ionomers, and resin composites)•It cannot provide thermal protection.

CLINICAL CONSIDERATIONS• Thickness of varnish :2-5 micrometer.• The varnish is usually applied in a thin consistency, using

a brush or small cotton pledget.• At least two thin layers of varnish should be applied to

obtain a uniform and continuous coating on all surfaces of the prepared cavity.

• After the first layer dries (using trisyringe), small pinholes usually develop. This layer effectively covers only 55% of the surface. The second layer is recommended to produce sealing of 82-85% of the surface and produces a more continuous coating.

Location for placement of cavity varnish.

Cavity varnish is applied on all the walls of the cavity

CONTRAINDICATIONS OF VARNISH

• Beneath GIC and Silicate : it prevents its chemical adhesion with tooth surface and reduces its anticariogenic effect.

• Beneath Composites: it inhibits the polymerization of resins.

CAVITY LINERS• The original purpose of cavity liners was to utilize

the beneficial effect of calcium hydroxide material by accelerating the formation of reparative dentin

• It is placed as a thin layer (<0.5mm) on the surface of a cavity preparation only on the pulpal floor.

• Provide a thin barrier that protects the pulpal tissue from irritation caused by physical, mechanical, chemical, biologic elements, restorative materials, intraoral fluids, influx of bacteria, and may provide some therapeutic benefits.

• E.g:calcium hydroxide,zinc oxide eugenol ,GIC

TYPES OF LINERS

1.Solution liners : Any liner based on nonopaque solvents that rely on evaporation for hardening is designated as solution liner.

- Thickness:2-5 micrometer2.Suspension liners: Any liner based on water

have many of the constituents suspended instead of dissolved are suspension liners.

- Thickness:20-25 micrometer.

TYPES OF LINERS

3.Cement liners: These are thicker liners selected primarily for pulpal medication and thermal protection.

- Thickness:0.2-1 micrometer

BASES

• Materials that are applied in thicker layers (>0.75mm).

• Used to replace missing dentin, encourage recovery of the injured pulp, protect the pulp from thermal and galvanic shock, mechanical trauma, chemical irritation, & resist forces applied during condensation of a restorative material.

TYPES OF BASES• It is of two types. 1) High strength bases: - They are used to provide thermal protection

for the pulp as well as mechanical support for the restoration.

- They have high strength ,modulus of elasticity.

E.g: Zinc Phosphate, Zinc Polycarboxylate, Glass Ionomer & Reinforced ZOE.

2) Low strength bases:• They have minimum strength & low rigidity.• Their main function is to act as a barrier to

chemicals & to provide therapeutic benefit to the pulp.

• E.g: Calcium Hydroxide & Zinc Oxide Eugenol.

BASES• Function:

– Insulator– Support for restoration

• Mixing: Mixed into a thick putty like consistency that

can be rolled into a ball or rope.• Placed in a 0.75 mm thick layer.

SUBBASE

• These are the therapeutic materials placed in the deeper portions of the cavity preparation as they possess specific pharmacological actions .

• They should always be covered with supporting base.

• E.g. :Calcium hydroxide , Zinc oxide eugenol

Ideal properties of cavity bases• Should provide Thermal

insulation , Chemical barrier ,Electrical insulation.

• Should provide appropriate strength, flow and thickness.

• Must allow adequate time for mixing and placement into the cavity

• Must have rapid setting

• Resist fracture• Radiopaque• Compatible with other

restorative materials• Biocompatible• High compressive and

tensile strength• Easy manipulation• Antimicrobial• Prevent microleakage • Demonstrate insolubility

in oral fluids

Types of Base Materials

•Zinc oxide eugenol •Zinc phosphate •Zinc Polycarboxylate•Glass ionomer

Dental bases provide pulpal protection.1. Protective base: Protect the pulp before

the restoration is placed.2. Insulating base: Protect the tooth from

thermal shock.3. Sedative base: Soothens the pulp that has

been damaged by decay or irritated by mechanical means.

USES OF BASES

Location for placement of a base.

Base should be applied only on the floor of the cavity because if it is applied on cavity walls it will dissolve by coming in contact with saliva

leading to microleakage and secondary caries.

CALCIUM HYDROXIDE•Considered either a cavity liner or base.

CALCIUM HYDROXIDE

Composition

Base: -Calcium tungstate-Tribasic calcium phosphate-Zinc oxide in glycol salicylate

Catalyst:-Calcium hydroxide-Zinc oxide-Zinc stearate - ethylene toluene sulphonamide

Composition, structure and properties of a typical liner: Calcium Hydroxide (Dycal)

COMPONENTSComponents 1 and 2

Setting reaction

Paste (with calcium hydroxide); light cured resin, and polyphenolics(1 component)

Acid-base reactionSTRUCTUREArrangement

BondingComposition (phases)Defects

Amorphous matrixCrystalline fillersCovalent; ionicMultiphasePores; cracks

PHYSICAL PROPERTIESLCTEThermal conductivityElectrical conductivityRadiopacity

LowInsulatorInsulator-

CHEMICAL PROPERTIESSolubility (% in water)Shrinkage on setting

0.3-0.5 (high)-

MECHANICAL PROPERTIESElastic modulus (MPa)HardnessElongation (%)Compressive strength>24 hr (MPa)Diametral tensile strength (MPa)Flexural strength (MPa)Shear bond strength to dentin (MPa)

588--138---

BIOLOGIC PROPERTIESBiocompatibility Acceptable

CALCIUM HYDROXIDEAdvantages Disadvantages

•Can be used virtually under all restorative materials,•Pulpal compatibility,•Promotes secondary dentin formation•Antibacterial,•Light cured formulations have rapid setting and lower solubility in water•Low cost•Easy manipulation •Good seal

•Low strength, plastic deformation•High solubility in water•Short term seal against bacteria•Long term microleakage•Poor physical properties

CLINICAL CONSIDERATIONS

• Indicated for direct and indirect pulp capping• To mix a calcium hydroxide liner, equal lengths of

catalyst and base are dispensed near each other on mixing pad.

• Pastes quickly mixed together for 20 seconds with the tip of the spatula and then scraped off the pad and swiped across the surface of the mixing pad.

• Final mix is identified by a homogenous colour. • The mixture is picked up using an applicator tip and

transferred into the cavity.

Location for placement of calcium hydroxide

ZINC OXIDE EUGENOLClassification

•Considered either a cavity liner or base

ZINC OXIDE EUGENOLCompositionPowder: -Zinc oxide-Magnesium oxide-Zinc acetate

Liquid: -Eugenol-Olive oil-Acetic acid

Zinc oxide eugenol liners contained in two tubes: Catalyst paste-Zinc oxide-Accelerator in a resin.

Base Paste:-Eugenol with an inert filler

SETTING REACTION OF ZINC OXIDE EUGENOL

• It involves chelation of two molecules of eugenol with one molecule of zinc oxide that forms zinc eugenolate.

2C10H12O2 + ZnO Zn(C10H11O2)2 + H2O

REINFORCED ZINC OXIDE EUGENOL

Composition•Reinforced zinc oxide eugenol is of two types.- One contains a polymer and the other contains aluminium oxide particles with the chemical ethoxybenzoic acid (EBA). -Both are powder and liquid systems with the polymer- reinforced version containing 20% acrylic polymer (methyl methacrylate)which is added to the zinc oxide powder. The liquid contains EBA and eugenol.

The zinc oxide eugenol is reinforced to enhance the strength of cement.

Composition, structure and properties of a typical liner: Zinc oxide eugenol (IRM)

COMPONENTSComponents 1 and 2Powder/liquid or paste/paste ratioSetting reaction

Zinc oxide; Eugenol6.0/1.0 by weightAcid-base reaction

STRUCTUREArrangement


Crystalline matrixCrystalline fillersCovalent; ionicMultiphasePores; cracks

PHYSICAL PROPERTIESLCTEThermal conductivityElectrical conductivityRadiopacity

LowInsulatorInsulator-


Modest-


---71---


ZINC OXIDE EUGENOLAdvantages Disadvantages

•Excellent initial sealing ability against biological leakage•Reduced postoperative sensitivity•Stimulates reparative dentin formation•Least irritating material with sedative effect on the pulp•Excellent thermal insulation•Bactericidal•Biocompatible•Prevents microleakage

•Toxicity of high concentrations of eugenol•Rapid disintegration on exposure to the oral cavity•Inability to withstand condensation forces immediately after placement•May mask pathologic symptoms•Direct pulpal contact with eugenol may result in necrosis•Poor physical properties•Inhibits composite polymerization •Increases microleakage under amalgam restorations•Some people are allergic to eugenol.


• Zinc oxide eugenol can be prepared as either a thick or thin mixture.

• Liners supplied as two pastes are mixed with a steel spatula or other appropriate instrument on a mixing pad/glass slab.

• Equal amounts of the base and catalyst are dispensed and quickly mixed for about 20 seconds until a homogenous colour of the paste is attained. The liner is then applied in a thin layer to the dentin with a special applicator.

CLINICAL CONSIDERATIONS• Only difference between mixing ZOE base/liner is the consistency. • Bases usually contain a higher powder to liquid ratio of 4:1.• Powder to liquid ratio: for luting -2.8:1 for base- 4.8:1• Zinc oxide eugenol bases are mixed rapidly in a single increment or in

two separate increments of powder.• Either a paper pad or glass slab can be used. Sufficient powder is added

to a few drops of eugenol and mixed until a thick putty-like texture is reached which can be handled without sticking to the fingers.

• A small piece of the base is attached to the tip of the explorer and placed carefully within the cavity without smearing it on the edges of the cavity walls. Then, a small cotton pellet is held in cotton pliers and used to mould the material within the cavity. Further increments can be added until enough bulk is achieved.

GLASS IONOMERS

•Considered either a cavity liner or base.

GLASS IONOMERSCompositionPowder: -Silica-Alumina-Aluminium fluoride-Calcium fluoride-Sodium fluoride-Aluminium phosphate

Liquid: -Polyacrylic acid with itaconic, maleic or tricarboxylic acid to reduce viscosity.-Tartaric acid might be added to improve handling properties, to increase working time, and reduce setting time-Zinc oxide or barium glass may provide radiopacity.

GLASS IONOMERS

•These products are available as hand-mixed (e.g. Vitrebond), encapsulated (e.g. Ketac-bond/Fuji Lining LC) and self-cured/light cured formulations. •The powder portion of the light activated glass ionomer lining cement consists of conventional acid-soluble glass particles with a photo activated accelerator. •The liquids are aqueous solutions of polyacrylic acid or copolymers to which polymerizable methacrylates groups are attached.

Composition, structure and properties of a typical Base: Resin modified Glass Ionomer Cement (VITREMER)

COMPONENTSComponent 1 Component 2Powder/liquid ratioSetting reaction

F-Al-Si glass powdermonomers/water2.5:1Acid-base reaction, free radicals



Amorphous matrixGlass fillersCovalent; ionicMultiphasePores; cracks

PHYSICAL PROPERTIESLCTEThermal conductivityElectrical conductivity

(Low)InsulatorInsulator

CHEMICAL PROPERTIESSolubility (% in water) 0.20 (low)MECHANICAL PROPERTIESModulus (MPa)HardnessElongation (%)Compressive strength(MPa)Diametral tensile strength (MPa)

---20035

BIOLOGIC PROPERTIESSafety Acceptable

Composition, structure and properties of a typical liner: Traditional Glass Ionomer (Fuji Lining LC)

COMPONENTSComponents 1 and 2Powder/liquid or paste/paste ratioSetting reactionSetting time

Powder (Al-silicate glass); liquid (polyalkenoate acid, LC resin)1.4/1.0 by weightAcid-base reaction (2-6 mins)



Amorphous matrixCrystalline fillersCovalent;ionicMultiphasePores;cracks

PHYSICAL PROPERTIESLCTEThermal conductivityElectrical conductivityRadiopacity (mm Al)

LowInsulatorInsulator4


0.08 (low)24 (low)


1820--12824465.8


SETTING REACTION OF GIC

It is theoretical diagram showing complete cross linking between polyalkenoic acid chains

GLASS IONOMERSAdvantages Disadvantages

•Ionic bonding to tooth•Fluoride release with remineralization of tooth structure and the ability to absorb fluoride at the restoration interface•Coefficient of thermal expansion is similar to tooth structure•Helps reduce microleakage, marginal gap formation as well as postoperative sensitivity•Antimicrobial •Able to adhere to and seal dentin•Able to bond to adhesive restorations• Reduce volumetric polymerization shrinkage•Biocompatible •Excellent physical properties •Able to support restorations.

•Moisture sensitivity •Conventional glass ionomers have a lower sealing ability than the light cured materials and are relatively soluble in acidic environments, therefore may undergo rapid surface breakdown during etching•Cannot be used as direct pulp capping agents since they may cause an inflammatory pulpal response and do not stimulate the formation of dentinal bridges.

CLINICAL CONSIDERATION

CLINICAL CONSIDERATIONS• The only difference between mixing glass ionomers as a base or liner is the

consistency. Bases are mixed to a higher powder to liquid ratio .• Powder to liquid ratio :1.5:1 for luting/lining/base 3:1 for restorative• Smear layer removed by conditioning with polyacrylic acid (10-20%) for 10 to 20

seconds and rinsing with water for 20 to 30 seconds. • After conditioning and rinsing, the surface should be dried but not desiccated. • The powder/liquid ratio recommended by the manufacturer should be closely

adhered to. • A oil immersion paper pad is indicated for mixing . • A cool & dry glass slab may also be used to retard the reaction & extend working

time. But the slab should not be used at a temperature below the ‘Dew Point’.• Powder & Liquid should not be dispensed until just prior to mixing since

prolonged exposure to the atmosphere can alter the precise acid/water ratio. • Mixing time should not exceed 45 to 60 seconds, at this time the mix should

have a glossy appearance which indicates unreacted polyacid which is critical for bonding. A dull appearance indicates inadequate free acid for bonding.

RESIN

Resins can be used as liners or bases however, they are not generally used as a base.

RESINSCompositionResins -Based on Bis-GMA (addition product of bisphenol A and glycidylmethacrylate) or urethane dimethacrylate-Diluents monomer triethylene glycol dimethacrylate (TEGMA))

Fillers Which may either be macrofilled, microfilled, nanofilled or hybrid (such as quartz, fused silica, glasses e.g. aluminosilicate and borosilicate)

RESINS

• Initiator/Activator: For chemical cured- -Benzoyl peroxide -Tertiary amine For light cured- -Amine -Diketone

• Other constituent: -Silane coupler -Pigments -Stabilizer

Chemically initiated (auto cured) with a peroxide initiator and an amine accelerator or it can be photo initiated with visible blue light in the presence of a light sensitive absorber such as camphorquinone and an accelerator such as aliphatic amine.

Some products use a combination of chemical and photo initiation for their polymerization reaction.

SETTING REACTION OF RESINS

• High compressive and tensile strength, have low solubility, high translucency and are available in different viscosities and shades.• Many flowable composites release fluoride . however, this fluoride release has been reported to be low and the rate of release significantly decreases during the first 3 weeks.• Fully polymerized resins do not cause pulp irritation . however, unpolymerised resins are a potential hazard. Water sorption and solubility is higher in micro-filled composites than in macro and hybrid types. • Composites undergo polymerization shrinkage

RESINS - Properties

RESINS - Properties• Microfillers have lower wear resistance than macro filled

composites. • Rigidity or the stiffness of micro filled materials is lower than

hybrid and macro filled types • Hybrid and macro types have higher fracture toughness,

compressive and tensile strength compared to the micro filled types.

• Microfilled composites portray greater creep (permanent deformation under occlusal load). Composites have a higher thermal coefficient of expansion than the tooth crown and amalgam and they may also be radiopaque helping in the detection of secondary caries.

RESINSAdvantages Disadvantages

• Micromechanical bonding to tooth• Thermal insulation • Greater strength than glass ionomer.•Improved working properties •Can reduce microleakage.

•Polymerization shrinkage•Gap formation•Post operative sensitivity•Technique sensitivity.


• Dentine bonding agents are of various types and their performance differs.

• Resins are not recommended for direct pulp capping because they do not promote the formation of dentine bridges and when used for direct pulp capping, there is persistent mild inflammatory pulpal response.

ZINC PHOSPHATE (ZINC OXYPHOSPHATE)

Generally considered a base material. However, one of its products (Doc’s Best Copper Cement) can be used as a liner.

ZINC PHOSPHATE

CompositionSupplied as a powder-liquid combinationPowder: - zinc oxide- magnesium oxide

Liquid: -Phosphoric acid-Water-Aluminium phosphate -May also contain zinc phosphate.

Composition, structure and properties of a typical base: Zinc Phosphate Cement (Modern Tenacin)

COMPONENTSComponent 1 Component 2Powder/liquid ratioSetting reactionSetting time

Zinc oxide powderPhosphoric acid/water3.5:1Acid-base reaction2-8 minutes



Crystalline matrixCrystalline fillersIonicMultiphasePores and cracks

PHYSICAL PROPERTIESLCTEThermal Electrical

LowInsulatorInsulator

CHEMICAL PROPERTIESSolubility (% in water) 0.10 (low)MECHANICAL PROPERTIESModulus (MPa)HardnessElongation (%)Compressive strength(MPa)Diametral tensile strength (MPa)

---77-


SETTING REACTION OF ZINC PHOSPHATE

3ZnO + 2H3PO4 + H2O Zn3(PO4)2.4H2O

Mixing of cement: Powder is divided into increments and each increment is mixed till desired consistency of cement is achieved

MIXING OF ZINC PHOSPHATE

• The powder is divided into 2 small increments,2 bulk increments followed by small increments .The 2-5 drops of liquid is taken in front of small increments.

2 small increments 2 large increments

• Mixing is initiated by addition of small increments of powder to liquid as slow addition of powder delays setting reaction and increase working time as well as reduces acidity .The larger increment is added in the middle of the mixing to further saturate liquid with newly forming complex .finally, small amount of powder is added to one to get cement not to go beyond desired consistency.

ZINC PHOSPHATEAdvantages Disadvantages

•High strength•Easy manipulation•Thermal, mechanical and chemical barrier•Final restoration can be placed on it after several minutes•Inexpensive•Excellent physical properties

•Acidic nature may lead to postoperative sensitivity•Not very biocompatible•Poor sealing ability•Can lead to microleakage•Lacks antibacterial properties•Brittle•Lack of adhesion •Soluble in oral fluids

CLINICAL CONSIDERATIONS• Powder/liquid ratio is 2.8:1 for luting 4.8:1 for base• The liquid should not be dispensed onto the glass slab until the

clinician is ready to mix so that evaporation is avoided. • The powder should be divided into several portions and mixing should

be initiated by the addition of a small amount of powder to the liquid. • Small quantities of powder should be incorporated initially with

vigorous, circular motion. Each increment may be mixed for 15 to 20 seconds before another increment is added.

• When the powder and liquid are mixed, heat is generated (exothermic reaction). Therefore, mixing should be carried out on a cold glass slab & over a wide area.

• When using ZOP as a base, the mixture should be viscous, resulting in a putty-like material which can be easily applied to the cavity preparation.

ZINC POLYCARBOXYLATE/ZINC POLYACRYLATE

Can be used as a base as well as a liner.

ZINC POLYCARBOXYLATE

CompositionPowder-liquid system and may also be available in encapsulated forms.Powder:-Zinc oxide -A small amount of magnesium oxide (which may be substituted by stannic oxide or stannous fluoride to modify the setting time and to improve the strength and handling properties of the material). The amount of fluoride released is about 15% to 20% of that released from glass ionomer.-Oxides such as bismuth and aluminium can be added.2

Liquid:-Polyacrylic acid -Water.

Composition, structure and properties of a typical base: Polycarboxylate Cement (Drelon)

COMPONENTSComponent 1 Component 2Powder/liquid ratioSetting reactionSetting time

Zinc oxide powder and waterPolyacrylic acid/waterHighAcid-base reaction5 minutes



Amorphous matrixCrystalline fillersCovalent; ionicMultiphasePores and cracks

PHYSICAL PROPERTIESLCTE*Thermal Electrical

LowInsulatorInsulator

CHEMICAL PROPERTIESSolubility (% in water) LowMECHANICAL PROPERTIESModulus (MPa)HardnessElongation (%)Compressive strength(MPa)Diametral tensile strength (MPa)

---10017


ZINC POLYCARBOXYLATEAdvantages Disadvantages

•Chemical adhesion to tooth structure• Excellent biocompatibility with the pulp• Low incidence of postoperative sensitivity•Short setting time•Self etching•Slight fluoride release from some products•Enables placement of the final restoration in the same visit

•Difficult mixing and handling•Needs accurate proportioning•Has lower strength and greater viscosity than zinc phosphate•Shorter working time


• Powder/liquid ratio is : 1.5:1 for luting 2.3:1 for base• The powder-liquid ratio may vary among different brands

but generally it may be between 2 to 3 parts of powder to 1 part of liquid by weight. (Mixed on glass slab)

• The liquid should only be dispensed when it is ready to be mixed since exposure of the liquid to the atmosphere results in evaporation which may increase its viscosity.

• The material must be placed into the cavity preparation before it loses its glossy appearance.

CLINICAL CONSIDERATIONS• The glossy appearance indicates sufficient free carboxylic acid for

bonding to the tooth. On the other hand, a dull looking mixture portrays an insufficient amount of unreacted carboxyl groups for bonding.

• The material is mixed by incorporating large quantities of the powder into the liquid. The mixing should be completed in 30 to 40 seconds. When placing the cement into the cavity and shaping it, dry powder is used to prevent the cement from sticking to the instruments.When mixing, the powder is incorporated into the liquid at once, as opposed to a little at a time as with mixing zinc phosphate.

• When mixed with potassium nitrate, this material serves as an effective liner, base and cement. However, it may be difficult to use this material as a liner due to its viscosity. For a base, a thicker, drier mix should be made where the final restoration can be immediately placed.

REMAINING DENTIN THICKNESS• The basic factor in determining the choice of using

cavity varnish , liner or cavity base is the thickness of remaining dentin bridge at the deepest portion of the cavity preparation.

GUIDELINES FOR PLACEMENT OF CAVITY VARNISH, LINERS AND BASES

RESTORATION SHALLOW CAVITY

MODERATELY DEEP CAVITY

DEEP CAVITY

RDT->2 mm RDT-0.5-2 mm RDT-< 0.5 mm

SILVER AMALGAM VARNISH/ DENTIN BONDING AGENT

BASES CALCIUM HYDROXIDE LINER AND BASE

COMPOSITE RESIN DENTIN BONDING AGENT DENTIN BONDING AGENT CALCIUMHYDROXIDE LINER AND GIC BASE

GLASS IONOMER CEMENT - -

CALCIUMHYDROXIDE LINER

CAST GOLD INLAYS AND ONLAYS

LUTING CEMENT BASE NAD LUTING CEMENT

CALCIUM HYDROXIDE LINER,BASE AND LUTING CEMENT

CERAMIC INLAYS AND ONLAYS

DENTIN BONDING AGENT AND RESIN CEMENT

DENTIN BONDING AGENT AND RESIN CEMENT

CALCIUN HYDROXIDE LINER,GIC BASE,DENTINBINDINGAGENTAND RESIN CEMENT

CONCLUSION• The concepts and materials relevant to liners and bases are

always changing and it is apparent that no one material is ideal for every clinical situation.

• Based on the “ideal properties of liners/bases,” none of the materials possess all of the ideal properties.

• However, there are some materials which can be considered almost ideal for the application of liners and bases.

• These include glass ionomers and zinc polycarboxylate. • Both materials offer various advantages including thermal,

chemical and electrical protection, acceptable strength, compatibility with other restorations, ability to immediately place restorations, biocompatibility, antimicrobial properties, prevention of microleakage as well as low solubility in water.

CONCLUSION

• Glass ionomers, unlike zinc polycarboxylate also offer the advantage of radiopacity, adequate flow and easy manipulation amongst various other benefits.

• Therefore, although no one material possesses all the ideal characteristics, literature favours Zinc Polycarboxylate (bases) & Glass Ionomer (liners & bases)

REFERENCES1. Anusauvice KJ. Phillips’ science of dental materials. 11th edn. 2. Craig RG, ed. Restorative dental materials. 3. Phillips RW. Skinner’s science of dental materials.4. Sturdevant -The art and science of operative dentistry. 5. Operative dentistry-material,theory and practise by Marzouck6. Applied dental material -9th edition by john Macabe and

Anguswalls7. Science of dental material-by V Shamma Bhatt, B T Nandish

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