1. Glass Ionomers Cements
Dr Kilasara/Zubeda

2. Overview Glass ionomers Characteristics Classification
Conventional GIC
Resin based GIC
Light cured GIC
Clinical uses

3. Glass Ionomer: “glass” refers to the glassy ceramic particles and the glassy matrix (non-crystalline) of the set material, while “ionomer” refers to ion-crosslinked polymer

4. Glass Ionomer Development
Glass ionomer cements are hybrids of the silicate cements and the polycarboxylate cements.
The intention was to produce cement with characteristics of both the silicate and polycarboxylate cements.
(translucency and
fluoride release
adhesion
kindness to the pulp

5. Early Glass Ionomers Poor esthetics Prolonged setting reaction
rough surface
Prolonged setting reaction
Poor wear resistance
Vulnerable to hydration extremes
Handling difficulties

6. Modern Glass ionomers Refined formulation Improved packaging
addition of tartaric acid
more reactive acids
Improved packaging
Metal modification
Addition of resin

7. Advantages Inherent (chemical) adhesion to tooth structure
Fluoride release
Linear Coefficient of thermal expansion (LCTE) similar to tooth structure
Biocompatible

8. Disadvantages Sensitive to moisture and desiccation
Low fracture toughness
Low flexure strength
Low wear resistance
Relatively poor esthetics

9. Indications Direct restorative Class 5 Root caries Class 3
Pediatric dentistry
resin-modified version
Tunnel preparations
Atraumatic restorative treatment (ART)

10. Indications Luting agents Liners Caries control Core block-out
Occlusal sealant

11. Contraindications Stress-bearing areas in permanent teeth
Class 1, 2 and 4

12. Classification
GICs are commonly classified into four principal types: 1. Conventional Glass Ionomer Cements 2. Hybrid Ionomer Cements Also known as Light or Chemical Cured Resin-modified Glass Ionomer or Dual-cured Glass Ionomer Cements Tri-cure Glass Ionomer Cements 4. Metal-reinforced Glass Ionomer Cements

13. Conventional Glass Ionomer
Composition
powder
ion-leachable calcium aluminofluorosilicate glass
liquid
copolymers of acrylic acid and/or
water
copolymers freeze-dried, placed in powder
maximize shelf-life

14. Production
It is an acid-soluble calcium fluoroaluminosilicate glass similar to that of silicate but has a higher alumina-silicate ratio which increases its reactivity with liquid.
The fluoride portion acts as a “ceramic flux”. Lanthanum, Strontium, Barium or Zinc Oxide additives provide radioopacity.
The raw materials are fused to form a uniform glass by heating them to temperatures of 1100◦C to 1500◦C. The glass is ground into a powder having particles into a powder in the range of 15 to 50 µm

15. GIC powder composition
Ion-leachable glass
silicon dioxide41.9%
aluminum oxide 28.6%
calcium fluoride15.7%
aluminum phosphate 3.8%
sodium fluoride 9.3%
aluminum fluoride 1.6%

16. Acid component Polyacids Tartaric acid acrylic maleic itaconic
tricarboxylic acid
Tartaric acid
improves handling
extends working time
sharpens set
increases strength

17. Setting Reaction (conventional)
Ion-leaching phase
acid attack on glass
H+ from polyacid
Al+3, Ca+2, F- migrate and form complexes
hydrogel forms around glass particles
Ca+2 predominate early
NaF formed
not native of matrix
physical properties not affected by depletion
Mn+ H+
COO-

18. Setting Reaction (conventional)
Hydrogel Phase
Ca+2 & Al+3 polysalts crosslink polymer chains
causes viscosity increase & hardening
poor physical properties
very susceptible to moisture
protect with matrix, bonding agent
COOH
COO-
COO-
COO-
M1+
COO-
M3+
COOH
M2+
COO-
COO-
COO-
COOH
COOH

19. Setting Reaction (conventional)
Polysalt-Gel Phase
slow maturation of matrix
Al+3 polyacrylate polymers predominate
stronger, less soluble
maturation may require 6 months–1 yr
Later stage susceptible to dehydration
protect with bonding agent

20. Conventional Glass-Ionomer Setting Reaction
COO- H+
Mn+
COO- H+
Mn+ H+
COO-
Mn+
Fluoroaluminosilicate Glass
COO- H+
COO- H+
COOH
COO-
COO- H+
Ca2+
Polyacrylic Acid
COO-
COO-
COO-
Tooth
COO-
M1+
COO-
Conventional Glass-Ionomer Setting Reaction
M3+
COOH
M2+
COO-
COO-
COO-
COO-
Ca2+
COO-
COOH
COOH

21. Resin-Modified Glass Ionomers
First developed as liners
Modified light- and/or chemically-activated methacrylate side chains
on polyacrylic-acid molecules
free in solution
HEMA
Total set resin 4.5–6%

22. Resin-Modified Glass Ionomer
Attempt to combine benefits
glass ionomer
fluoride release
adhesion
composite resin
strength
esthetics
Attempt to reduce
glass ionomer
hydration sensitivities
delayed set
poor early strength
composite
polymerization shrinkage
microleakage
recurrent caries
Glass Ionomers
RMGI
Compomers
Composites

23. Resin-Modified Glass Ionomer
Composition
powder
ion-leachable glass
liquid
initiators
copolymers of acrylic acid
methacrylate groups grafted and/or HEMA
and/or
water
copolymers freeze-dried, placed in powder
maximize shelf-life

24. Setting Reaction (RMGI)
COO-
COOH
Poly-HEMA
Traditional glass-ionomer acid-base reaction
proceeds more slowly
Free-radical polymerization
similar to composites
light initiated
chemical
Cross-linked resin-reinforced matrix

25. Free-Radical Polymerization
Visible-light
photoinitiator
camphorquinone
most common
absorbs blue light
initiator reacts with amine activator
Chemical
mix separate pastes
benzoyl-peroxide initiator
tertiary-amine activator
Forms free radicals
Initiates addition polymerization
methacrylates
grafted and/or free
Camphorquinone
Benzoyl Peroxide
O O O
H2C=C-C-O-CH2-CH2-OH
CH3 O
HEMA

26. Resin-Modified Glass-Ionomer Setting Reaction
Mn+ H+
COO-
HEMA
H2C=C-C-O-CH2-CH2-OH
CH3 O
HEMA
HEMA
HEMA
Fluoroaluminosilicate Glass
COO- H+
Polyacrylic Acid
Poly-HEMA
COO-
Ca2+
COO-
COO-
COO-
Tooth
COO-
M1+
Resin-Modified Glass-Ionomer Setting Reaction
COO-
M3+
COOH
M2+
COO-
COO-
COO-
COO-
Ca2+
COO-
COOH
COOH
Davidson, GI Cements 1999
Poly-HEMA

27. Material-Related Variables
Fluoride release
Adhesion
Biocompatibility
Physical properties

28. Fluoride Release Rapid early release from matrix
Slow, long-term release from particle
Does not take part in matrix formation
does not result in loss of physical properties
Amount of release similar for both conventional and RMGI F-
Al3+
COO-

29. Adhesion to Tooth Structure
M3+
COO-
COOH
Ca2+
Tooth
Conventional GI
ion exchange
GI – tooth substrate
carboxyl groups of GIC
bond with Ca+2 of hydroxyapatite
Resin-modified GI
ion exchange similar to conventional GI
resin-impregnated hybrid layer?
equivocal

30. Biocompatibility Favorable large molecules buffering of dentinal fluid
limited tubule ingress
buffering of dentinal fluid
relatively weak acid
initial high acidity
chemical adhesion
minimizes microleakage
antimicrobial activity

31. Properties Strength Polishability Fluoride Release Glass Ionomers RMGI
Compomers
Composites
Strength
Polishability
Fluoride Release

32. Classifications Applications Chemistry Type 1: luting cements
Type 2: restorative cements
esthetic restoratives
reinforced restoratives
condensable
metal-modified
Type 3: liners/sealants
Chemistry
conventional GI
traditional acid-base reaction
resin-modified (RMGI)
acid-base reaction
light and/or chemical cure

33. Luting Cements (Type 1) Conventional Resin-modified (RMGI)
Ketac-Cem (3M ESPE)
Fuji 1 (GC)
Resin-modified (RMGI)
greater strength
less moisture sensitivity
less soluble
examples
Fuji Plus and FujiCem (GC)
Rely X (3M ESPE)
                                                   

34. Orthodontic Luting Agents
Fluoride releasing
Bonds in moist environment
Condition surface
etch optional
Only light-leveling wires first 24 hrs
Examples
Fuji Ortho (GC)
Fuji Ortho LC (GC)

35. Endodontic Obturation
Fluoride releasing
Radiopaque
Short working time
More difficult to retreat
Example
Ketac-Endo (3M EPSE)

36. Applications Type 1: luting cements Type 2: restorative cements
esthetic restoratives
reinforced restoratives
condensable
metal-modified
Type 3: liners/sealants

37. Esthetic Restoratives (Type 2)
Conventional
examples
Ketac-Fil (3M ESPE)
Fuji II (GC)
Glasionomer Type II (Shofu)
RMGI
Fuji II LC (GC)
Vitremer (3M ESPE)
Riva Light Cure (SDI)

38. Esthetic Restoratives Case Selection
High caries risk
Areas of lower stress
permanent Class 3 & 5
esthetics not paramount
Pediatric dentistry
RMGI version

39. Esthetic Restoratives Technique Tips
Surface must be clean
Remove smear layer
Tooth must be moist

40. Esthetic Restoratives Conditioning Dentin
Conventional GI
polyacrylic-acid conditioner
removes smear layer
cleans surface
promotes adhesion
RMGI
follow manufacturer’s directions
polyacrylic-acid conditioner or adhesive

41. Esthetic Restoratives Moisture Content
Sensitive to moisture levels
ion exchange in hydrated medium
desiccation
extracts water from cement
excess water
dilutes matrix

42. Esthetic Restoratives Finishing
Conventional GI
surface coat
wait 15 minutes
minimize trauma to surface
use blades
slow speed

43. Esthetic Restoratives Finishing
RMGI
surface coat
immediate finishing
normal armamentarium
fine diamond
polishing discs
gentle technique

44. Esthetic Restoratives Surface Protection
Protect setting cement
early moisture contamination
desiccation later
Unfilled resins
essential
conventional
optional
RMGI
more resistant to water loss
fills irregularities
color stability
decreased F release

45. Esthetic Restoratives RMGI Liners
Posterior composite
“open-sandwich” technique
dentinal gingival margins
reduced leakage
reduced gap formation
examples
Fuji II LC (GC)
Vitremer (3M ESPE)

46. Applications Type 1: luting cements Type 2: restorative cements
esthetic restoratives
reinforced restoratives
condensable
metal-modified
Type 3: liners/sealants

47. Reinforced Restoratives (Type 2)
Condensable
Metal-modified

48. Condensable (Type 2) Conventional GI Indications Examples
simplified handling
Indications
provisionalization
pediatric restorations
Atraumatic Restorative Treatment
field dentistry
hand instrumentation
Examples
Fuji IX (GC)
Ketac-Molar (3M ESPE)

49. Metal-Modified Glass Ionomers (Type 2)
Conventional GI
silver fused with powder
e.g., Ketac-Silver (3M ESPE)
amalgam alloy mixed with powder
e.g., Miracle-Mix (GC)
Improved handling,radiopacity,wear resistance
Fluoride release
similar or slightly less than conventional

50. Metal-Modified Glass Ionomers (Type 2)
Indications
non-stress bearing areas
core build-ups
low strength
minimize size
block-out
caries control
provisionals
Atraumatic Restorative Treatment

51. Applications Type 1: luting cements Type 2: restorative cements
esthetic restoratives
reinforced restoratives
condensable
metal-modified
Type 3: liners/sealants

52. Liners (Type 3) Conventional RMGI examples Ketac-Bond (3M ESPE)
Lining Cement (GC)
RMGI
Vitrebond (3M ESPE)
Fuji Lining LC (GC)

53. Sealants (Type 3) Glass-ionomer Resin-based sealants
“pre-cooperative” children
partially-erupted permanent molars
examples
Riva Protect (SDI)
Fuji Triage (GC)
click here for DECS evaluation
Resin-based sealants
higher retention
similar efficacy
Simonsen, Pediatr Dent 2002
proper isolation necessary

54. Compomers Composite and Glass-ionomer
Polyacid-modified composite resin
Matrix
dimethacrylate monomer
carboxylic groups
Filler
ion-leachable glass
No water
COO-H2C-H2C-H2C-H2C
CH2-CH2-CH2-CH2-OOC
H2C=CH
CH=H2C
C C
HOOC
COOH
Matrix Example

55. Setting reaction Free-radical polymerization reaction
similar to resin composites
resin-based adhesives
No chemical bond to tooth structure
Low levels of fluoride release
Delayed acid-base reaction
water from tubules, absorption

56. Compomers in Dentistry
Direct restorations
restoratives
flowables
Cements

57. Advantages Easy to place and polish Some fluoride release
More esthetic than glass ionomer
Better mechanical properties than glass ionomer
Glass Ionomers
RMGI
Compomers
Composites

58. Disadvantages Inferior mechanical properties
compared to composite
Less fluoride release than glass ionomer
minimal recharge
No chemical bond to tooth structure

59. Indications Esthetics Areas of lower stress class 3, 5 pediatric
conservative class 1 and 2

60. Contraindications Stress-bearing areas Poor isolation
permanent Class 1 or 2
increased wear
loss of marginal integrity
Poor isolation

61. Giomers Resin-based restoratives
Pre-reacted glass-ionomer particles (PRG)
fillers from conventional GI reaction
Free-radical polymerization reaction
similar to light-activated resin composites
No chemical bond to tooth structure
More research needed
Example
Beautifil (Shofu)

63. USES Glass-ionomer cements are used for the
cementation of cast-alloy and porcelain restorations and orthodontic bands
cavity liners or base materials,
restorative materials, especially for erosion lesions