Transcript glass ionomer cement

GLASS IONOMER
CEMENTS
INTRODUCTION
GIC is an adhesive tooth
coloured restorative material used
for eroded areas and now it has
been used for other areas also .
Salt formed by reaction
between poly alkenoic acid and
Calcium aluminoflurosilicate glass .
HISTORY
developed by Wilson & Kent in 1972 .
Yogi etal - 1992 –
GI cement is used as a sealent for
partially erupted permanent molars .
Groll etal – 1993 –
Recommended light curable glass
polyalkeonate for amalgam replacement .
Althadaing etal - 1994 – light cured glass ionomer
for repairing furcated
areas on the pulpal floor .
Thevadans etal – 1996 – Mixing of 4 % NaF with GIC.
.
Historical evolution of GIC
Also named as……
 polyalkeonates .
.
 ASPA (aluminosilicatepolyacrylic acid )
developed by Wilson etal 1970 .
ADVANTAGES
 Tooth coloured material .
 It will adhere directly to both enamel and dentine
through ion exchange mechanism .
 Biologically active as it is capable of releasing
fluorides , calcium and phosphate .
CLASSIFCATION
CLASSIFICATION
TYPE I - Luting
TYPE II – Resoration .
TYPE III – Liners and bases .
TYPE IV - Pit and fissure sealants .
TYPE V – Orthodontic cements .
TYPE VI – Core built up.
CLASSIFICATION……
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TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
TYPE
I
II
III
IV
V
VI
VII
VIII
IX
- Luting
- Restoration
- Liners & Bases
- Resin modified
- Metal modified
- Ceromers
- Compomers
- Geriatric
- Pediatric
CLASSIFICATION BY G J MOUNT
Based on the - water powder ratio.
physical properties .
clinical application .
TYPE I – Luting agents .
TYPE II i – Esthetic restoration .
TYPE II ii – Non esthetic restoration .
TYPE III - Liners and bases .
CLASSIFICATION NO:3
TYPE I
Conventional
TYPE II
Restorative
Class 1 – esthetic restorative cements .
Class 2 – reinforced restorative cements or metal
modified glass ionomer .
TYPE III
Light cured lining glass ionomer cement
( liners and bases ) .
TYPE I –CONVENTIONAL GI.
Mostly used in cementing , luting , liners and
bases .
Powder particle size – 15 micron .
Thickness of cement film – 2 micron .
Thin pulpal dentin is required to be protected
with hard Setting Ca ( OH )2 .
TYPE II RESTORATIVE GIC
Class I esthetic restorative cement
Mostly used for anterior restorations
Class II reinforced restoration cements
Class I reinforced restoration cement
( metal modified , posterior GI)
Mostly used for posterior restorations .
A ) Amalgam alloys mixed with cements.
B ) Cermet ( ceramic metal mixture )
Glass powder is fused and sintered with Ag
particles .
PROPERTIES
Resistance to wear as they are stronger and tougher .
Poor esthetics due metallic color
Less pulpal irritation .
Posses anticariogenic properties
TYPE 3 a – Light cured lining glass
ionomer cements
HEMA ( hydroxy ethyl methacrylate ) added to light
component .
Reduce shrinkage .
To increase strength , powder mixed with alumino –
silicate glass.
Light cured GIC
TYPE 3 b – Light cured glass ionomer cement
COMPOSITION
POWDER - ion leachable glass .
LIQUID - Polyacrylic acid
or
Polyacrylic acid with HEMA .
SETTING REACTION
Initial set – polymerization of methacrylate gp
Final set – slow acid – base reaction
PROPERTIES
Reduced translucency .
Increased tensile strength
Stronger adhesion to teeth surface .
Decreased marginal adaption and increased marginal
leakage due to polymerization shrinkage .
TYPE 4 Hybrid resin modified G I
Used as restorative filling material.
HEMA added to liquid component - bonding.
Have higher resistance to wear & tear.
Used in class 1,2,5 filling with conservative cavity
preparation.
Avoid cavities in deciduous teeth.
Light cured GIC
AVAILABLE AS…

Powder – liquid system .

Pre – proportionate capsule .

Light cure system .

Dual cure system (chemical +light) .
Luting ,restorative & root canal
cements
Cement dispensing system
COMPOSITION
POWDER
acid soluble calcium fluoro aluminosilicate glass
SiO2
-35-40%
Al2O3
-20-25%
AlF3
-1.5-3 %
CaF2
-15-20 %
NaF
-4-10 %
AlPO4
-1-15 %
Fluoride component - ceramic flux .
Lanthanum , strontium,barium , ZnOradiopacity .
Fine colloidal Ag and amalgam enhance the properties.
LIQUID
40 -50% acidic solution……
Poly acrylic acid .
Tartaric acid .
Water.
Poly acrylic acid – very viscous
Tendancy to gelation .
Poly acrylic acid co-polymerized with itaconic acid
maleic acid .
Increases the reactivity of liquid .
Decreases the viscosity .
Decreases the tendency to gelation .
TARTARIC ACID
Improve the handling character .
Decreases the viscosity .
Increases the working time .
Decreases the setting time .
WATER
Most important constituents .
Too much of water- weak cement .
Too little water – dehydration .
SETTING REACTION
The liquid acid may be freeze dried and combined with
powder [ to have better shelf life and lower viscosity
which are important characteristics for luting agents .
Mix can be done on a disposable moisture resistant paper
pad or a glass slab .
A plastic spatula is preferred to a metal one to minimize
contamination of the mix from eroded metal .
Large increment of powder are rapidly incorporated into
the liquid and mixing should be completed within 40 sec
Working time – short , not more than 3 min from start of
mixing .
SETTING
REACTION
Powder and liquid mixed together
Acid attacks the glass particles .
Na,Ca,Al ,F ions are leached into the
aquous solution
Ca poly salts in the beginning and later
Al – poly salts .
Two salts cross links to form polyanionic
chain.
STRUCTURE OF SET CEMENT
Agglomerates of un reacted
powder particles surrounded by silica gel
and embedded in an amorphous matrix of
hydrated Ca-Al polysalts .
Fresh cement once
hardened is prone to cracking and crazing
due to loosely bound water which is
readily removed from mix .
Setting time –
Type 1
Type 2
4 – 5 min
7 min
STEPS IN GI
RESTORATION
• Cavity preparation
• Conditioning of tooth preparation
• Proper manipulation
• Protection of cement from setting
• Finishing
CAVITY PREPARATION
Proper adhesion → resistance →
retention is achieved by proper cavity
preparation .
Eroded rough surfaces can be
restored after acid etching alone without
proper preparation.
CONDITIONING OF TOOTH PREPARATION
.
Chemical adhesion of cement with tooth surface
Surface should be free of saliva, blood and
completely dry .
Smear layer on the cavity should be removed .
This is done by
Pumice wash
10 % polyacrylic acid
37 % H3PO4
Time 10 to 20 sec
Surface of dentin after
application of……….
37% ortho phosphoric
acid
10% poly acrylic acid
PROPER MANIPULATION
P/L ratio -
type I
type II
Hand mixing
Capsule mixing
3:2
3:1
Hand mixing
Divide the dispersed powder into two equal parts .
Powder is incoperated rapidly into liquid .
Mixing should be done in a folding manner in
order to preserve the gel structure .
10 sec after adding first increment , 2nd
increment is added to liquid .
The final mix should be with in 25 to 30 sec .
CAPSULE MIXING
Amalgamator is used for mixing
Powder and liquid contained within capsule by
removing the seal separating the liquid and powder .
After mixing is completed by vibration nozzle of the
capsule is pierced and the cement is dispersed directly on
the prepared cavity .
Advantage
Control over p/l ration
Convenience
Mechanical mixing
PROTECTION OF CEMENT
DURING SETTING
Matrix placement
Matrix removal
MATRIX PLACEMENT
Pre contoured matrix is placed over the cement in
the cavity for a period of 5 – 8 mts
ADVANTAGES
- Provide best possible surface integrity
- provide maximum contour
- prevent loose or gain of water from cement before
initial setting is completed .
MATRIX REMOVAL
– After initial setting the matrix is removed.
Excess material is removed by sharp hand
instrument BP knife .
-Cement then coated with:
-light curable bonding agent
-Vaseline
This prevent loose or gain of water . dehydrated
restored cement become weak due to microcracks.
FINISHING
Before dismissing the patient , apply one or
more layer of protective agents .
GIC is not advised in patient with
xerostomia , with mouth breathing habits
(restoration are susceptible to dehydration) .
Occlusal caries on mandibular 1st
molar
Caries excavation using spoon excavator
Completed caries excavation
CEMENT PLACED
Excess cement removed
Finishing done
LOSS OF GLOSS OR SLUMP TEST
USES
For luting
For restorations
Liners and bases
Fissure sealants
Orthodontic purpose
Core build up
Intermediate Restorations
Adhesive Cavity Liners (Sandwich Technique)
ART (Atraumatic Restorative Technique)
Restorations for deciduous teeth
Luting Agents
Excellent for permanent cementation of crowns, bridges.
Releases fluoride reduces sensitivity by giving a firm
foundation for composites.
Fast setting - low film thickness & low viscosity.
P/Lratio………… 1.5:1
Typical Physical Properties:
Mixing Time: 15 seconds
Setting Time: 2 minutes
Working Time: 2 minutes
Luting agent
Orthodontic Bracket Adhesives
 Most commonly used .

They bond directly to tooth by the interaction of
Polyacrylate ions and hydroxyapatite crystals, thereby
avoiding acid etching.

Anticariogenic effect fluoride releasing ability.
Pit and Fissure Sealants
Cements were found to be unsuitable for
use as sealnts if the fissures were less than
100µm wide.
The material is mixed to a more fluid
consistency to allow flow into the depths of
the pits & fissure of the posterior teeth.
Carious pit & fissures on
mandibular molar
Conditioner applied
Placement of the cement
Liners and Bases
GICs have a number of advantages as cavity
lining as they bond to dentine and enamel and
release fluoride
-prevent decay & therefore minimizing the
chances of appearance of secondary carries
-promote the formation of secondary dentine.
They can be used as base for both
composite resin and amalgam.
GIC as a Base ( P/L ratio-3:1)
Class III cavity preparation in 32
-Liner placed for pulp prottection
( P/L ratio – 3:1 )
GIC as a lining – 0.5mm thick
For Core Build Up
Silver containing GICs (cermet, Ketac Silver, Espe,GMbH
or 'miracle mix' of GIC &unreacted amalgam alloy have been
used.
Cermet used to fill deciduous teeth .
Addition of Ag radiopacity to diagnose secondary caries.
To protect a GIC core crown margin should completely
embrace 1-2 mm of sound tooth structure cervically.
Extension of crown margin -ferrule effect
Advantages:
to tooth Intrinsically adhessive
Fluoride release - freedom from 2° decay
Similar coefficient of thermal expansion
DEVELOPING
A CORE
Intermediate Restorations
Due to inherent adhesive nature & brittleness
To restore loss of tooth structure from the
roots of teeth [cervical abrasion cavity-product
of over zealous tooth brushing]
Used frequently as in non-undercut cavities,
to ensure their retention
Deep caries
Temporary restoration - GIC
Adhesive Cavity Liners (Sandwich
technique)
Involves using GIC as dentin replacement and a
composite to replace enamel
Surface
should be coated either with an
unfilled resin or a DBA to optimize attachment.
ART (Atraumatic Restorative Treatment)
The technique uses simple hand instruments (such as
chisels &excavators) to break through the enamel & remove
caries
The cavity is loaded using cotton rolls.
Then residual cavity is restored using a modified GIC.
These GICs are reinforced to give increased strength
under
functional loads and are radio opaque.
Restorations for Deciduous Teeth
Due to high fluoride release ,minimal cavity
preparation & adhesion to dental hard tissue.
Restoring carious teeth is one of the major
treatment needs of young children.
And because they require a short time to fill the
cavity, Glass ionomer cements present an additional
advantage.
PROPERTIES
Film Thickness
The film thickness of GICs is similar to or less
than that of zinc phosphate cement and is
suitable for cementation.
MECHANICAL PROPERTIES
Compressive strength
– 150 mPa
Tensile strength
– 6.6 mPa
Hardness
– 49 khn
The resin-modified materials have been shown to
have significantly higher tensile strengths and lower
modulus of elasticity than the conventional materials.
ADHESION
Good adhesion to enamel and dentin.
Bonding occurs between exchange of ions .
Some degree of bond is also developed between GI
& collagen fibres of dentin.
Bond to enamel more than dentin , due to its high
inorganic content and homogenesity .
ION EXCHANGE ADHESION BETWEEN
TOOTH & CEMENT
AESTHETICS
Inferior to silicate and composite .
Lack translucency and have rough surfaces
texture .
Rough surface texture .
Margin Adaptation and Leakage
The coefficient of thermal expansion of
conventional GI is close to that of dental hard
tissue- so good margin adaptation of GI
restorations.
Shear bond strength of GIC doesnt approach
that of dentin bonding agent, resin-modified GIC
exhibit microleakage .
This may be partly because their
coefficient of thermal
expansion is higher than
conventional materials, though still much less than
composite
BIOCOMPATIBLITY
High degree of compatibility to living tissue
Polyalkenoic acid with high molecular weight is
difficult to penetrate throught dentinal tubules .
Induce secondary dentin formation in mechanically
exposed pulp .
In deep cavities Ca(OH)2 should be used to
prevent post operative sensitivity .
RESISTANCE TO PLAQUE- Lack of plaque
build up relative to adjacent teeth
ANTICARIOGENIC PROPERTIES
GIC is considered as a fluoride reservoir
Remineralisation of tooth structure due to release of Ca
, PO4 and F ions
Streptococcus mutans is unable to thrive in the presence
of F ions . so low accumulaton of plaque .
Minimize the white spotting and decalcification which is
seen around orthodontic brackets .
Orthodontic bands on posterior teeth – luting agent of
choice is GIC
FLUORIDE RELEASE
Fluoride re-uptake & releaseafter recharging with NaF gel
WATER BALANCE
Susceptible to both water loose and
water uptake.
Type 3 cement remains susceptible to
water uptake for at least one hrs to 25 hrs
after placement.
Resin modified G I were developed to
overcome this problem.
CLINICAL IMPORTANCE
GIC susceptable to dehydration should be coated
with varnish during dental procedure .
Contraindicated in mouth breathers and xerostomia
patients due to dehydration .
Failure to protect with matrix / varnish / resin bond
agent will result in chalky / crazed surface .
Decreased P/L ratio gives chalky surface .
Liquid with PAA not to be refrigerated which
increases viscosity.
DISADVANTAGES OF CONVENTIONAL
GIC
Short working time
Sensitivity to moisture exposure
Dehydration during setting.
Lower cohesion strength.
Less resistence to abrasion and wear than composite .
MODIFICATION OF
GIC
Resin modified GIC .
Metal modified GIC .
Fast setting materials .
Water settable GIC / anhydrous .
Compomers .
RESIN
MODIFIED
GIC
Cement are light cured by adding 5% resin
matrix to GIC .
They also retain the acid – base reaction .
RESIN MODIFIED GIC
COMPOSITON
Ion leachable glass ( fluoro alumino silicate
glass )
Polymerisable resin.
Photo initiator or chemical initiator or
both .
PAA
LIQUID
H2O
Methacrylate monomer .
Hydroxy ethyl methacrylate monomer (HEMA) .
The acid base raction will continue even in the
absence of light activation .
Clean lesion with pumice & water
• Condition with
10% poly acrylic
acid for 10sec
Apply pressure during placement to
minimise porosity & good wetting of the
tooth
Trimming & contouring under air –
water spray
PROPERTIES
Microleakage more than GIC due to
polymerization .
Good anticariogenic property due to
increased F content.
Pulpal response mild .
Good esthetics .
USES
Class 1
Class 2
Class 5
For repair of cavities .
Class V non carious lesion
restored with RMGIC
METAL MODIFIED
GIC
Miracle mix
Cermet
CERMET
Filler particles are added…………
To improve Strength
Fracture toughness
Resistence to wear
CERMET REPAIR ON BUCCAL CUSP OF
BICUSPID HAS BEEN IN PLACE FOR 6years
& APPEARS STABLE
Metal modified GIC
MIRACLE MIX
Also called silver alloy admix .
Spherical amalgam alloy powder mixed with
type II GIC .
Not used in anterior teeth – due to radio
opacity and metallic color .
Miracle mix
CERMET
Ag particles are bonded to glass particles by
sintering ( fusion at high temp)
USES
Alternative to amalgam and composite .
In core build up in grossly destroyed
teeth .
PROPERTIES
Excellent anticariogenic property due to F ions.
More resistance to wear than GIC.
.
Poor esthetics –radiopaque and gryeyish in color.
FAST SETTING MATERIALS
Glass in these cements has been chemically
modified during manufacturing to decrease the Ca2+
content and thus limit the production of Ca-poly
alkeonate chains which are highly water soluble .
Faster maturation of setting reaction .
Decrease the translucency .
WATER SETTABLE GIC (ANHYDROUS)
Polyacrylic acid co-polymer is freeze dried and
coated to powder particles.
The liquid part is water or water with tartaric acid.
When powder is mixed with water the polyacrylic acid
goes in to solution to form liquid acid.
Cements undergo chemical reaction.
Cements set faster than normal cement.
Have improved physical properties.
COPOMER (POLYACID MODIFIED RESIN )
Hybridisation of composite and glass ionomer
Composite + ionomer = copomer
Variable degree of dehydrated polyalkenoic acid
incoperated with filler .
The setting reaction is light activated .
Subsequent absorption of water from saliva into
restoration will release small amount of fluorides
Adhesive system is based on acid
etch or resin bond system and no ion
exchange adhesion.
Used in children.
Have minimal steps in placement.
Aesthetically pleasing.
Finished case
TUNNEL RESTORATION
First discribed in 1963
Conservative alternative cavity
preparation in primary molars.
Indication
Small proximal caries with out
involvement of marginal ridges
SANDWICH TECHNIQUE
GIC is sandwiched between tooth and composite resin.
Used in case of deep carious lesion.
ADVANTAGE
Etching avoided in deep caries- avoid pulpal
irritation.
Better strength is achieved .
Prevent recurrent caries due to F ion release .
Chemical bonding to tooth achieved by GIC .
Open sandwich
restoration
Closed sandwich
restoration
Lamination with amalgam
• Combination of GIC with amalgam
• To with stand heavy occlusal load.
• STEP –I , A strong GI base(auto cured
or resin modified) is applied first.
• Fine layer of 45% poly acrylic acid
applied over cement – ensure chemical
bonding.
• STEP II , Pack amalgam over this.
• Mechanical interlocking occure between
two
…………STEP I
STEP II……………
CONCLUTION….
• No one material is universal and it is
unlikely that such an ideal material
limitations, bt each one , used to its
full potential , has aplace in
restorative dentistry.there have been
20years of close clinical observationof
GIC
Text book of pedodontics - Shobha
Tandon
•
Preservation &restoration of tooth structure Graham J Mount
•
Text of pediatric dentistry - S.G.Damle
• Pediatric dentistry,infancy through
adolescence
•
- Pinkham
• Dentistry for the child & adolescent
- Mc Donald,Avery,Dean
• Sturdevant”s Art & Science of Operative
Dentistry
THANK YOU