glass ionomer Metal-Modified GIC Resin-Modified GIC dental material

1. GLASS-IONOMER
CEMENT
Acid-Base Reaction Cements:

2. Glass-Ionomer Cement
 The word glass-ionomer is a generic name
derived from material’s composition
 The powder is ion-leachable glass (Calcium-
flouro-alumino-silicate) that is able to react
with ionomeric acid containing carboxyl groups
(e.g. Poly acrylic acid)
 Sometimes the name Polyalkenoic cement is
used

3. General Applications
 Final cementation
 Cavity base and liner
 Esthetic Filling material
(in eroded cervical lesions)
 Bonding agent
 Fissure sealer
 Endodontic sealer
 Filling of deciduous teeth
 Amalgam Bonding

4. Cementation of orthodontic brackets

5. Classification of G.I. cements
A. According to the use
 Type I: Luting material (P.size < 15 m)
 Type II: Esthetic Filling material (P.size =20-50 m)
 Type III: Cavity base and liner
B. According to The curing mechanism
 Chemical-cured: Cement sets via acid-base reaction
 Dual-cured: Cement sets via both polymerization and
acid-base reactions
 Triple-cured: Cement sets via chemically-activated
polymerization, light-activated polymerization and
acid-base reactions

6. Classification of G.I. cements
C. According to the modification
 Conventional GI: No modification -- Sets via acid-base
reaction
 Metal-modified: Ketac silver and Cermet--Sets via
acid-base reaction
 Resin-modified:-- Either dual or triple-cured

7. Presentation forms
1. Powder-liquid
- To be mixed using plastic spatula over paper pad
2. Water-settable powder
- Dry powder of PAA copolymer is blended with cement
powder in the same bottle.
- The material is mixed with regular water
3. Capsules
- Both cement powder and liquid are contained in the
same capsule and separated from each other by a
diaphragm
4. Two-paste system
- Recently introduced as a cement (luting material)
material.
- Equal lengths to be mixed over a paper pad

9. Conventional G.I. cements
Composition
 Powder:
1. Calcium-fluoro-alumino-silicate glass particles
- All compositional ingredients (CaF2, Al2o3, Sio2, NaF,
AlPo4) are fused together at 1100-1500oC  ingot
then grind into the desired particle size
2. Radio-opaque glass particles in which barium or
strontium replaces the calcium

10. Conventional G.I. cements
Composition
 Liquid:
1. Aqueous solution of Poly-alkenoic acid
- PAA or its copolymer with maleic or itaconic acid
- Sometimes the acid may present in the dry powder
form to be blended with cement powder in case of
water-settable material
2. Tartaric acid
To  viscosity of PAA and to  the setting time

11. Conventional G.I. cements
Setting reaction
 Chemical reaction of acid-base type
 H+ from the acid attacks the aluminum sites
 Decomposition of the surface of glass particles
 Release of Ca++ and Al+++ ions into the aqueous medium
 the Ca++ and Al+++ cross-link the poly acrylate chains
by forming poly-acid sol (initial setting)
 the sol transfers into poly-acid gel forming cement
matrix (hardness and strength)
 surface of the un-reacted glass particles is coated
with a layer of silica gel

12. Conventional G.I. cements
Setting reaction
 The set material is composed of;
 Non-reacted powder coated with silica gel
in an amorphous matrix of hydrated poly-
acid salts (gel (Calcium and aluminium
poly-acid gel)
 Water is a component of the set material.
The loosely bonded water could
evaporate out of the material
 desiccation and contraction
 Fluoride ions remain free, and released
only when the material becomes wet

13. Conventional G.I. cements
Manipulation
1. Mixing
• Mixing is achieved over a paper pad using plastic
spatula
• Stainless steel spatula is contraindicated to avoid the
contamination of mix by the abraded metal particles
• Large amount of powder is incorporated into the
liquid at once
• Thin mix  cementation
• Thick mix filling or cavity base
2. Tooth should be cleaned or even conditioned by PAA
before cement application

14. Conventional G.I. cements
Manipulation (Cont.d)
3. Restorative material
• Should be inserted as one bulk into the cavity
• The excess is removed after partial setting using
sharp hand instrument
• The material left to set in 24 hrs and then finished
4. Surfaces of fillings or margins of cement should be
protected from saliva by applying varnish or resin
coating
5. Recoating is strongly recommended after finishing
and polishing

15. Characters of conventional G.I.
cements
1. Biological properties
• Freshly-mixed cement may cause mild or moderate
pulp irritation, accordingly deep cavities should be
lined with calcium hydroxide
• The material provides chemical bonding to both tooth
structure and restoration surfaces -->  the rate of
microleakage
• The fluoride release --> help in  the rate of caries
recurrence
2. Interfacial properties
 The material is chemically-bond to the apatite part of
the tooth, base metal alloys and tin-plated gold alloys

16. 3. Chemical properties
• The set G.I. cement is more resistant to solubility in
oral fluids than other cements based on the acid-base
reaction
• However, fresh cement is easily soluble in saliva and
the material should be protected either with resin or
varnish coating
4. Mechanical properties
 The cement is stronger on compression than other
zinc-oxide based cements
 However, the set material is brittle having low DTS
and fracture toughness
Characters of conventional G.I.
cements

17. 5. Esthetic properties
• The set G.I. cement is translucent and could be used
to cement ceramic restorations
6. Thermal properties
 The cement has low thermal diffusivity and could be
used as cavity base under amalgam restorations
7. Practicability
 The cement is easily mixed on paper pads using only
non-metallic spatulas
Characters of conventional G.I.
cements

18. 7. Practicability (Cont.d)
 Cleaning and conditioning of tooth surfaces together
with using the freshly-mixed material all improve the
bond
 The material could be used as a liner under composite
restorations (Sandwich technique)
 Restorative material should be applied as one piece
while filling tooth cavities (bulk filling technique) as
the increments do not cohere together
 Resin or varnish coating is required to protect the
setting material
 Careful and delayed (after 24 hrs) finishing should
followed with resin or varnish coating
Characters of conventional G.I.
cements

19. Metal-Modified
Glass-Ionomer Cements
Inclusion of metal particles within the
composition or the structure of cement’s
powder

20.  Cement powder is a simple blend of regular glass and
amalgam particles
 The blend is reacted with regular cement liquid (PAA)
 The mixed material sets via acid-base reaction
typically as that of the conventional glass-ionomer
1. Ketac Silver
 Characters of the modified material
- Shows a little bit higher strength than
that of Conventional G.I.
- Shows an increased rate of solubility
- Become opaque with gray metallic
color
- Used to fill the primary molars

21.  A small amount of silver is fused with cement’s glass
particles at the time of manufacturing
 The resulted particles react with regular cement
liquid (PAA) and the mixture also sets via acid-base
reaction typically as that of the conventional glass-
ionomer
 Characters of the modified material
- Shows higher strength and better resistance to
wearing than the conventional G.I.
- The material is also opaque having gray metallic color
- Used for core build-up and as posterior filling in
selected cases
2. Cermet

22. Resin-Modified
Glass-Ionomer Cements
(RMGI)
Inclusion of resin monomer to form (after its
polymerization) a protective matrix in which the
regular cement setting takes place
The resultant material owns a dual mechanism of
setting that includes both polymerization and
acid-base reactions
Dual-cured Cements:

24. A. Powder
 Alumino-silicate glass particles
 Polymerization initiator
 Chemical initiator (Benzoyl peroxide) in case of
chemically-activated polymerization
 Photo-initiator (Camphroquinon) in case of light-
activated polymerization
 Both in case of triple-cured materilas
A. Liquid
 Aqueous solution of Poly-alkenoic acid
 Poly-acrylic acid having some carboxylic groups
modified with methacrylate or HEMA monomer
Composition of RMGI

25.  The initial and rapid setting of the material is
provided through polymerization of resin monomer
 Slow acid-base reaction also takes place within the
cured resin matrix. This reaction is responsible for
maturing process and the final strength
 The water content is too little to complicate the
polymerizaton, however its presence is essential for
the acid-base reaction.
Setting of RMGI

26. The modification provides material having
 Higher strength and fracture toughness than that of
conventional G.I.
 Lower solubility of the freshly-set material
 Possibility for immediate finishing and polishing
 No need for resin or varnish coating
 Lower rate of fluoride release
Characters of RMGI

27.  Esthetic filling materials in non-stress bearing areas,
cervical erosions
 Fissure sealant
 cavity base and liner
 Bonding agent
 Core building-up material
 Cement for ceramic restoration
Applications of RMGI

28. Continuum of Esthetic Restoratives
Composite Compomer Giomer RMGI GI

29. CEMENTS SET BY
POLYMERIZATION REACTION
A. Resin composite cement
B. Resin compomer cement
Note.
 Composite = Resin matrix + inorganic fillers +
coupling agent + polymerization initiator
 Compomer = polyacid-modified composite resin

30. A. RESIN COMPOSITE CEMENTS
 Firstly developed in the early 1970s to be used with
adhesive/ resin bonded bridges
 They are less heavily-filled composites (filler load = 65%)
 These materials set via polymerization reaction
 Present materials can be classified according to its mode
of polymerization into chemical-cured, light-cured, and
dual-cured

31. RESIN COMPOSITE CEMENTS
A. Chemically-cured composite cement
 Many types contain on 4-META (4-methacryloxy ethyl
trimellitic anhydride), that provides good bonding to
several metal alloys
 Used for;
1. Cementation of resin-bonded bridges
2. Cementation of any metal restoration (inlay, onlay, crown)
3. Placement of bonded amalgam restoration

32. RESIN COMPOSITE CEMENTS
B. Visible light-cured composite cement
 VLC materials utilize a polymerization system
similar to that of VLC composites
 These materials are available in different shades to
help in production of good esthetics
 Some manufacturers provide a try-in pastes have
the same color shade of actual cement (water-
soluble paste used during try-in stage)
 Used for luting ceramic veneer

34. Cementing ceramic veneers
Labial veneer
Palatal surface
Resin composite
cement
Labial gingiva

35. RESIN COMPOSITE CEMENTS
C. Dual-cured composite cement
 Dual-cured materials could be polymerized by both
light or chemical activation (i.e. polymerized even if
they do not receive sufficient light)
 Usually supplied as two-paste system, one of them
are used to determine the shade
 Used for luting composite and ceramic inlays, endodontic
posts, and ceramic crowns

36. RESIN COMPOSITE CEMENTS
ADVANTAGES:
 Low solubility in oral fluids (resin-based material)
 Good strength properties (presence of fillers)
 Low film thickness (low filler loading)
 Good esthetics (color shade and color stability)
DISADVANTAGES:
 Poor wear resistance than regular composites
 Require the use of bonding agent
 Material’s polymerization could be affected in presence of
moisture or oxygen …… the exposed cement margins
should be coated with air-inhibition gel

37. B. RESIN COMPOMER CEMENTS
A kind of resin-based cement, used to cement
cast and metal-ceramic restorations
COMPOSITION:
 Powder:
Alumino-fluoro-silicate glass, sodium fluoride, self
and/or light-cured initiator
 Liquid:
Methacrylate-carboxylic acid monomer, diacrylic
monomer, water

38. RESIN COMPOMER CEMENTS
ADVANTAGES:
 Provide chemical bonding to tooth structure….. through
the present carboxylic acid groups of the monomer
 Fluoride release help in inhibition of recurrent caries
 High compressive and flexure strengths = composite
cement
 Higher fracture toughness > glass-Ionomer cement

39. Self-etching self-adhesive resin cements
 All types of resin cements require etching,
application of bonding agent to the surfaces (tooth &
restoration) to be cemented
 These new kind of resin-based cements contain
phosphate-based monomer that have the ability to
etch and chemically bond to tooth structure