Glass ionomer cement

GLASS IONOMER CEMENT

BY: NIKHILA N KASHYAP

CONTENTS Introduction History Composition Classification Dispensing Manipulation Setting reaction Properties Indications and contraindications Advantages and disadvantages

INTRODUCTION What is a cement? A cement is a substance that hardens

to act as a base ,liner ,filling material ,or adhesives to bind devices or prosthesis to the tooth structure or to each other.

GLASS IONOMER CEMENT It is a tooth colored materialBased on reaction between silicate glass powder and polyacrylic acid Chemically bind to tooth structure ADA specification number 96

HISTORY Invented in 1969 Reported by wilson and kent in 1972 The term was coined by B.E KENT Other names: Ionomer poly-carboxylate acid ISO terminology Poly-alkenoate cement Since its extensive usage to replace the

dentin-dentin substitute , man-made dentin, artificial dentin

ASPA- alumino silicate poly-acrylate.

COMPOSITION

Species Composition(%)

Silica (SiO2) 30.1Alumina (Al2O3) 19.9Aluminium fluoride (AlF3)

2.6

Calcium fluoride (CaF2)

34.5

Sodium fluoride (NaF) 3.7Aluminium phosphate (AlPO4)

10.0

Powder: It is an acid soluble calcium fluoro aluminosilicate glass

LIQUID Species

composition(%)Polyacrylic acid 40-50%

water 50%

Itaconic acid , maleic acid , tri carboxylic acid

0.5%

Tartaric acid 5-15%

CLASSIFICATION

According to A.D WilsonI. Type 1: Luting agentsII. Type 2: Restorative cements a)aesthetic filling material b)bis-reinforced filling

materialIII Type 3: Lining, base and fissure

sealing materials

According to application Type 1) luting Type 2) restoration Type 3) liners and base Type 4) pit and fissures sealants Type 5) luting for orthodontic purpose Type 6) core build up material Type 7) fluoride releasing GIC Type 8) for ART Type 9) for pediatric purpose

DISPENSING

Commercially available in 2 forms 1. Encapsulated2. Powder and

liquid

MANIPULATION

1) Tooth preparation: Pumice slurry is used to remove the

smear layer. Etched with phosphoric acid and rinse tooth surface should be cleaned and

dried for sustained adhesion .

2) MATERIAL PREPARATION P/L ratio – 3:1 by weightpaper pad or dry glass slab is usedWHY?Powder and liquid is dispensed just before mixing

Powder is incorporated rapidly into the liquid

Half of the powder is mixed into liquid for 5-15 seconds , rest is then quickly added and mixed to get a uniform glossy appearance .

CLINICAL STEPS

In cervical abrasion cases

Pumice prophylaxis

Dentin conditioning

APPLICATION OF GIC

FINISHINGExcess material must be trimmed from marginsHand instruments preferred to rotary instruments to avoid ditchingFurther finishing is done after 24 hours

SETTING TIME

TYPE 1 4-5 Minutes

TYPE 2

7 Minutes

SETTING REACTION Stage 1) Dissolution Stage 2)precipitation of salts, gelation

and hardening. Stage 3) hydration of salts

STAGE 1) DISSOLUTION Surface layers of glass particles are attacked by poly acids and ions are released

Produce diffusion based adhesion between glass particles and matrix

STAGE 2) PRECIPITATION, GELATION AND HARDENINGCalcium and aluminium ions bind to poly ionsInitial clinical set-Cross linking of ca ions -4-10 minutes from setting Next 24 hours –less mobile aluminium ions bound within the cement matrix – more rigid cross linking Fluoride and phosphate ions forms insoluble salts and complexesSodium ions – binds the powder to matrix

STAGE 3) HYDRATION OF SALTS progressive hydration of matrix salts Sharp improvement in physical

properties

SETTING RATE Manufacturer controlled glass composition

glass fusion temperature, powder particle size,

tartaric acid concentration Operator controlled Mixing temperature-storage of slab and

powder in a refrigerator increases the working time up to 25%

Powder: liquid ratio-inadequate liquid results in a decline in translucency and physical properties

PROPERTIES Adhesion: chemically binds to tooth

structure Bio compatibility: resistance to plaque ,

plaque fails to thrive on the surface of GIC

Pulpal response to GIC: formation of dentin bridge occur when used to protect a mechanical or traumatic exposure of pulp

Remineralising effect

Solubility : initial solubility is high due to leaching of intermediate products

is low when compared to zinc phosphate and zinc polycarboxylate

Dimensional change : volumetric setting contraction of approximately 3%

Strength : susceptibility to brittle fracture . Weak and lack rigidity when compared to composites and amalgams

Abrasion resistance : immediately after placement-less resistance to abrasion , as they mature their resistance improves

Thermal diffusivity Color and translucency: type II a) restorative esthetic material provide adequate color

matching and translucency Radiopacity:more radiopaque than dentin and

several exceed that of enamel Anticariogenic property: fluoride is released at

the time of mixing and lies within the matrix - flouride reserviour

MODIFICATIONF OF GIC1) Water settable GICLiquid used is clean waterLiquid is delivered in a freeze dried form ,which is

incorporated into the powder2) Resin modified GICPowder component consist of ion leachable

fluroalumino silicate glass particles and initiator for light curing

Liquid component consist of water and poly acrylic acid with methacrylate and hydroxyl ethyl methacrylate monomer

3) Metal modified GICGIC have been modified by addition of filler particles,

to improve strength fracture toughness and resistance to wear

Silver alloy admix / miracle mixThis is made by mixing of spherical silver amalgam

alloy powder with glass ionomer powderCermentBonding of silver particles to glass ionomer particles

by fusion through high temperature sintering

3) Compomer It is a composite resin that uses and ionomer

glass which is the major component of glass ionomer as the filler

Small quantity of dehydrated poly alkenoic acid incorporated with filler particles

Setting reaction is light activatedAdhesive system used with compomer is based

on acid etch found with all composite resin

ATRAUMATIC RESTORATIVE TREATMENTPRINCIPLES1.Removing carious tooth tissue using hand

instruments only2.Restoring the cavity with adhesive

material(glass ionomer)Why GIC?Chemically binds to enamel and dentinFlouride release to prevent and arrest cariesBiocompatible – no irritation to pulp and gingiva

INDICATIONS Type I) useful in patients with high caries index Type II) restoring of erosion / abrasion lesions without

cavity preparation sealing and filling occlusal pits and fissures restorations of class III lesions repair of defective margin in restoration core build up intermediate restoration Type III) lining of all types of cavities where a biological

seal and cariostatic action are required sealing and filling of occlusal fissures showing

early signs of caries

CONTRAINDICATIONS Class IV carious lesions or fractured

incisors Class II carious lesions where

conventional cavities are prepared Replacement of existing amalgam

restoration Lost cusp areas

ADVANTAGES Inherent adhesion to tooth structure Good marginal seal Anticariogenic property Biocompatibility Minimal cavity preparation required Restoration in primary dentition

DISADANTAGES Low fracture resistance Low wear resistance Water sensitive during setting phase Less esthetics compared to composites

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