What are 4 advantages of glass ionomers?
- Biocompatible
- Fluoride release
- Inherent (chemical) adhesion to tooth structure
- Coefficient of thermal expansion (CTE) similar to tooth structure
What are some disadvantages of glass ionomers?
- Sensitive to moisture and desiccation
- Low fracture toughness
- Low flexure strength
- Low wear resistance
- Relatively poor esthetics
What are some indications of glass inonomers?
- Class 5 restorations
- Root caries
- Class 3 restorations (resin modified version)
- Tunnel preparations
- Atraumatic restorative treatment (ART) - Spoon out caries, thumb in FUJI to control caries
What are some indications of glass ionomers?
- Luting agents
- Liners
- Caries control
- Core block-out
- Occlusal sealant
What are some contraindications of GI?
Stress bearing areas in permanent teeth
- Class 1, 2, and 4
What are the 2 types of basic GI?
- Conventional GI
- traditional acid-base reaction - Resin-modified (RMGI)
- acid-base reaction
- light and/or chemical
- free-radical polymerization
What is the composition of a conventional GI?
- Powder
2. Liquid
What was the goal of creating RMGI?
- Attempt to combine benefits of GI and Composites
GI: F release, chemical adhesion
Composite: Strength, esthetics
What was the goal to reduce when creating RMGI?
- Attempt to reduce
GI: hydration sensitivities, delayed set, poor early strength
Composite: Polymerization shrinkage, microleakage, recurrent caries
List the following restorative materials from softest to hardest:
RMGI
Compomers
Composites
Glass Ionomers
- GI
- RMGI
- Compomers
- Composites
Is initial F release from RMGI rapid or slow?
Rapid!
However, slow long term release from particle
Does not take part in matrix formation
Does F release in RMGI decrease its physical properties?
No!
Amount of F release is similar for both conventional and RMGI
How many days does the initial burst of F last from RMGI?
- High early release
1-2 days
Describe the F release pattern from RMGI after the initial burst during the first 1-2 days?
- Sustained low levels
- F reservoirs
- Uptake and re-release
- Can uptake topical fluoride and fluorides from tooth paste
- Only a fraction of initial F level
What are the effects of the F release from RMGI in the mouth?
- F levels are elevated in the saliva
- Enhancement of remineralization
- Incorporated into tooth structure
- Effective zone around restorative margin, up to 7.5 mm in enamel
How does F effect bacteria?
- Reduced bacterial metabolism
- Reduce acid production
- Reduced bacterial growth
What do studies show about the clinical efficacy of F releasing materials?
Equivocal
No conclusive, overall evidence of caries reduction when comparing glass ionomers versus controls
Do some studies suggest that RMGI has a role to play in caries reduction in the xerostomic patient?
Yes!
How does conventional GI bond to tooth structure?
Bond with Ca 2+ of hydroxyapatite
What is the pulpal response to RMGI?
Favorable!
- Large molecules: limited tubule ingress
- Buffering of dentinal fluid
- Relatively weak acid - initial high acidity
What is a major advantage of RMGI?
Adhesion!
Minimizes microleakage
Antimicrobial activity
What are the 3 applications of GI?
Type 1: Luting cements
Type 2: Restorative
- Esthetic restoratives
- Reinforced restoratives
- Condensable/metal modified
Type 3: liners/sealants
What are some examples of Type 1 luting cements?
- Ketac Cem
- Rely X
- FUJI I
Resin modified (RMGI)
- greater strength
- less moisture sensitivity
less soluble
Is cementing Empress crowns with a RMGI cement a good idea?
No!
GMRI cannot support, empress flexes too much
