2 -- Glass ionomer and RMGI Cements: Leme Kraus

glass ionomers are ____ based, ____-_____ restorative materials

water based

self-adhesive

Why should I use Glass ionomer based materials

Evidence of successful long-term use in high caries risk children, adults, older adults and institutionalize populations

what type of adhesion do glass ionomers use

chemical

self adhesive system (no need for an additional adhesive system)

_______-releasing materials are essential when treating high-caries-risk patients

fluoride

glass ionomers are ____ releasing

fluoride

glass ionomers are less resistant to _____ forces, so we use on class V

biting

glass ionomers can be used to _____ dental materials

cement

glass ionomers are indicated to eliminate _____ ____

active infections

using glass ionomer as a liner helps with ____ ___ and ____ protection

thermal insulation

pulp

glass ionomer can be used for both ____ and ____ restorations

permanent and provisional

glass ionomers can be used as a ____ under other restorative materials

liner

Gets covered with a final restorative material

Provisional restorations

As a placeholder until the patient can come back for the final restorations

Final restorations (which types of restorations)

Class V - good interface with dentin and cementum

Class I and II - more common in older adults and pediatric patients

Class III

- mainly in areas not under high loads

Cementation

Indirect restorations

Prefabricated or cast endodontic posts

Orthodontic appliances

Different types

Main type of GIC based on composition

Conventional Glass ionomer (GI)

Resin Modified Glass-ionomers (RMGI)

Glass-Hybrids (GH)

Metal reinforced GI

Images

Images

Glass ionomer cements classifications: Type I

cementing (luting) crowns, bridges, and orthodontic brackets

Glass ionomer cements classifications: Type II a

Esthetic restorative cements

Glass ionomer cements classifications: Type II b

Reinforced restorative cements

Glass ionomer cements classifications: Type III

Lining cements, bases

Glass ionomer cements: compositions

Powder: FluoroAluminoSilicate (FAS) Glass

Liquid: Aqueous solution of Polyacrylic acid

• manual mixing previously but now in a capsule form

what type of reaction do glass ionomer cements have

Acid-Base Reaction

Essential components in glass ionomer reaction

FluoroAluminoSilicate (FAS) Glass (powder)

Water (helps ion transport in the Acid-Base reaction and fluoride release)

Tartaric acid (helps to control the working time and setting characteristics of the material)

What are the functions of the water in a Glass ionomer

Helps ion transport in the acid-base reactions

Fluoride release

Setting reaction: Dissolution

Mixing FAS glass and polyacrylic acid in water-based reaction media

Setting reaction: Gelation and initial setting

The carboxylate ions react with metallic ions to form a salt bridge, resulting in gelation and setting

Release of F- as a result of the setting reaction and ion-exchange

Setting reaction: Hydration of salts and maturation

Strength of the cement builds up with time:

Silicic acid rapidly polymerizes to form silica hydrogel

When is the fluoride released

initial setting is when you have the most fluoride released and will continue up to 14 days where it then starts to slow down

RMGI composition

Polycarboxylic acid (liquid)

Fluoroaluminosilicate glass (powder)

Water (helps the ion transport needed for the acid-base reaction and fluoride release)

Hydrophilic methacrylate monomer (HEMA) photo-initiated/redox reaction

Free radical initiators (trigger curing of methacrylate groups)

RMGI: what are the two-types of reactions?

Traditional acid-base

Free-radical methacrylate polymerization

Setting reaction- RMGI

Mechanical properties: Compressive strength

Glass-ionomers: 170

RMGI: 210

RBC: 350 RBC>RMGI>GI

Dentin: 300

Enamel: 380

Mechanical properties: Flexural strength

Glass-ionomer: 30

RMGI: 90 RBC>RMGI>GI

RBC: 180

Mechanical properties: Tensile

Glass ionomer: 10

RMGI: 15

RBC: 50 RBC>RMGI>GI

Dentin: 106

Enamel: 10

Mechanical properties: Fracture toughness

Glass-ionomer: 0.25

RMGI: 0.7

RBC: 0.8-1.2 RBC>RMGI>GI

Dentin: 3

Enamel: 1

Mechanical properties: Wear rate

Glass ionomer: 73 glass ionomer has the fastest wear rate

RBC: 10-20

Enamel: 15-29

The more resin you add the less ______ ____ properties

fluoride releasing

Properties continued

Fluoride recharge-release - The highest level of F recharge comes from _____ and _____

highest level of recharge from GI and RMGI

- serve as fluoride reservoirs

- recharge with F toothpaste, NaF rinses and varnishes

RMGI ionomer is the best balance of

F- release

F recharge

Physical properties

Fluoride release

can you bevel with glass ionomers?

NO

Top Ten clinical guidelines (conventional GIC)

1. Always follow manufacturer's directions

Top Ten clinical guidelines (conventional GIC)

2. Cavity preparation: outline and depth should follow the extent of caries lesion

NO bevels

Top Ten clinical guidelines (conventional GIC)

3. Maintain good isolation: Rubber dam

Top Ten clinical guidelines (conventional GIC)

3. Maintain good isolation: Retraction cord

Top Ten clinical guidelines (conventional GIC)

4. Use of conditioner helps bonding

a. conditioning

- rule of 200 (% X time in sec = 200)

b. rinse

c. remove water excess

Two mechanisms of adhesion for RMGI:

Chemical bonding: ionic bonds between carboxyl groups and calcium from hydroxyapatite

Micro-mechanical interlocking: inter-diffusion layer

Top Ten clinical guidelines (conventional GIC)

5. Do not desiccate dentin before application

Top Ten clinical guidelines (conventional GIC)

6. Work efficiently (do not over manipulate)

Use minimum number of strokes (3-5)

Top Ten clinical guidelines (conventional GIC)

7. Avoid early contact with moisture

A transient _____ ______ is recommended to protect the GI from loss and uptake of water duing setting

surface protectant

Top Ten clinical guidelines (conventional GIC)

8. Avoid early finishing

Top Ten clinical guidelines (conventional GIC)

9. Gentle contouring and finishing

Finishing under water spray with superfine diamond, or carbide finishing bur, or silicone points

Top Ten clinical guidelines (conventional GIC)

10. Evaluate your work. Reflect

Oh ya she is looking good

Summary of Top Ten clinical guidelines

1. Always follow manufacturer's direction

2. Preparation without a bevel

3. Maintain good isolation

4. Use of conditioner helps bonding

5. Do not desiccate dentin before application

6. Work efficiently (do not over manipulate)

7. Avoid early contact with moisture

8. Avoid early finishing when possible

9. Gentle contouring and finishing

10. Evaluate your work. Reflect!

Do not use _________ ______ before Vitrebond

Cavity conditioner

Etching of the Vitrabond cured surface for _____ technique with resin composite is not deleterious

sandwich

SUMMARY: Chemical reaction

Ionization polyacrylic acid (water), dissolution of glass releasing ions, reaction carboxylic acid and Ca and Al ions from glass

SUMMARY: Water

importance (ionize acid and reaction media)

SUMMARY: Mechanical properties and Clinical indications

conventional has lower mechanical properties but more Fluoride release the moment you start adding more resin the higher the mechanical properties but the less Fluoride release

SUMMARY: Indications

high caries risk patients for GIC and RMGI due to Fluoride releasing properties

What are two critical roles water plays in the setting of GI

1. Serves as reaction medium for the initial dissolution

2. Hydration over time as it matures

3. Dilute matrix over time

1 and 2

You have a patient who has a large number of cervical restorations made of RMGI. The patient's restorations and teeth were recently cleaned with an ultrasonic scaler. What should you be concerned about

1. Nothing. I am glad patient got his teeth cleaned

2. Creation of a rough restoration surface has been associated with increased biofilm formation

2. Glass ionomer wear more

You have a patient who has a large number of cervical restorations made of RMGI. The patient's restorations and teeth were recently cleaned with an ultrasonic scaler. What should you be concerned about?

- Surface roughness

What should be done if that is the case ?

1. Repolish restoration

2. Apply a surface sealant

3. Monitor the restorations

4. All the above

4