Glass-ionomer Cements in Restorative Dentistry Question And Answers

Glass Ionomer Cement Long Essays

Question 1. Describe the merits and demerits of GIC. Write about its application.°

Answer:

Merits:

  • Chemical bonding to tooth structure
  • Bio-compatible
  • Good marginal seal
  • Anticarcinogenic
  • Translucent
  • Conservative
  • Less technique sensitive

Demerits:

  • Low fracture resistance
  • Low wear resistance
  • Opaque
  • Require moisture control

Applications:

Isolate the tooth

Tooth preparation
Conservative preparation
Minimal depth
No need of a retentive feature

Conditioning of tooth with 20% polyacrylic acid

Manipulation Of Cement:

Use of cool, dry glass slab/paper pad along with a plastic spatula

Dispense and divide the cement powder into 2 parts

Mix individuality for 20 sec.

Total mixing time 40-60 sec.

Restoration:

Carrying cement with a cement carrier

Placement into the preparation

Carving

Surface protection by petroleum jelly

Finishing and polishing after 24 hours

Glass Ionomer Cement Short Essays

Question 1. Clinical Indications and Contraindications for GIC.

Answer:

Clinical Indications and Contraindications for GIC:

Indications:

  • Restoration of Class 3, 5, and small Class 1
  • Non carious lesions
  • Root caries
  • Deciduous teeth
  • As luting
  • As liner
  • Preventive restoration
  • Core build-up
  • Splinting
  • Endodontic failure

Contraindications:

  • Stress bearing areas
  • Xerostomia
  • Mouth breathers
  • Cuspal replacement
  • Areas that require aesthetics

Question 2. Uses of Glass lonomers and add a note on biocompatibility.

Answer:

Uses of Glass lonomers:

1. As pit and fissure sealants

  • Due to anticariogenicity and adhesive properties

2. As liners and Bases – Beneath composite and amalgam

3. As luting agents

  • For cementation of crowns, bridges, veneers, and orthodontic bands

4. As orthodontic brackets adhesive

5. For restorations of class 3 and class 5 lesions

6. Fissure sealing

  • Use of high-viscosity GIC

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7. Restoration of root caries

  • Due to adhesion to dentin
  • Anticariogenicity
  • Ease of use

8. High caries Risk patients

  • Because of their adhesion
  • Abrasion resistance
  • Anticariogenicity

9. Temporary restoration

10. Core build-up

11. ART (Atraumatic Restorative Treatment)

  • Used in children with poor families
  • Small to moderate pit and fissure caries

Biocompatibility:

  • GIC is biocompatible due to
    • Polyacrylic acid is a weak acid
    • Dissociated hydrogen ions present in GIC bound to the polymer chains
    • The formation of long polymer chains prevents their penetration into dentinal tubules
    • Postoperative sensibility due to
      • Low viscosity
      • Low initial pH of the cement

Question 3. Bilayered restoration / Sandwich technique / Laminated technology.

Answer:

Bilayered restoration:

  • Developed by McLean et. al in 1985
  • Refers to a laminated restoration using glass ionomer to replace dentin and composite to replace enamel
  • Composite bonds micromechanically to set GIC and chemically to the HEMA.

Steps:

Isolate the tooth

Tooth preparation
Butt joint
Bevelling of enamel margin

Pulp protection using Calcium hydroxide

Tooth conditioning using polyacrylic acid

Placement of GIC

Etching of GIC surface

Coating with a dentin bonding agent

Placement of composite and curing

Finishing and polishing

Glass Ionomer Cement Sandwich technique- Gloss ionomer is placed in prepared tooth, over which composite resin is placed as laminate

Advantages:

  • Resistance to microleakage
  • Esthetics
  • Flouride release
  • Less polymerization shrinkage
  • Biocompatible

Disadvantages:

  • Technique sensitive
  • Time consuming

Question 4. Cermet Cement.

Answer:

Cermet Cement:

  • Introduced by McLean and Gasser
  • It is a fusion of glass ionomer to powder like silver or gold.

Manufactured:

  • Sinter compressed pellets made from fine metal powder and glass ionomers powder at 800oC
  • Ground it into fine form
  • Addition of titanium dioxide

Advantages:

  • Better abrasion resistance
  • Higher flexure strength.

Disadvantages

  • Poor aesthetics

Question 5. Resin-modified glass lonomer.

Answer:

Resin-modified glass lonomer:

  • Introduced as Vitreband (3M)
  • Incorporate the best properties of both GIC and composite resin

Composition:

  • Powder:
    • Fluorosilicate glass
    • Initiator
  • Liquid:
    • 15-25% resin component (HEMA)
    • Polyacrylic acid
    • Water

Advantages:

  • Long working time
  • Good adaptation
  • Chemical adhesion
  • Flouride release
  • Improved aesthetics
  • Good strength

Disadvantages:

  • Polymerization shrinkage
  • Limited depth of cure

Question 6. Type 2 GIC.

Answer:

  • It is restorative glass ionomer cement
  • It is further divided into

Type 2 – 1 – Restorative Esthetic:

  • Used for esthetic purposes
  • For classes 3, 5
  • Tunnel Restoration
  • The powder/liquid ratio is 3:1 or greater
  • They can either autocured or resin modified
  • Has superior physical properties
  • Good translucency

Type 2-2 – Restorative Reinforced Gic:

  • These have metallic inclusion
  • Have superior strength
  • Lack esthetics

Uses:

  • Core build-up
  • Root caries
  • Tunnel restorations
  • Deciduous restorations
  • Powder/liquid ratio – 3:1 or greater

Question 7. Advantages and disadvantages of Glass Ionomer cement.

Answer:

Advantages:

  • Chemical bonding to tooth structure
  • Bio-compatible
  • Good marginal seal
  • Anticarcinogenic
  • Translucent
  • Conservative
  • Less technique sensitive

Disadvantages:

  • Low fracture resistance
  • Low wear resistance
  • Opaque
  • Require moisture control

Glass Ionomer Cement Short Answers

Question 1. Tunnel Preparation.

Answer:

Tunnel Preparation:

  • Isolate the tooth
  • Place wedge below proximal portion
  • Penetrate occlusal surface – 2mm inside marginal ridge at 45° angulation
  • Removal of caries
  • Widen the preparation
  • Placement of band
  • Placement of restorative material and its condensation
  • Removal of wedge and matrix
  • Finishing and polishing

Glass Ionomer Cement Entry of bur should be at 45° to the lesion

Question 2. Modifications of GIC.

Answer:

Modifications of GIC:

Fiber Reinforced Glasses:

  • Alumina fibers, glass fiber, silica fiber, and carbon fiber added to cement
  • Improves flexure strength
  • Low abrasion resistance

Metal Reinforced GIC:

  • A mixture of amalgam alloy to GIC powder
  • Poor esthetics
  • Poor abrasion resistance

Cermet Cement:

  • Sintering metal and glass powders
  • Improved abrasion resistance
  • Higher flexural strength

Resin Modified Glass Tonomer:

  • Incorporate the best properties of both glass ionomer Cement and composite resin
  • Good adaptation
  • Flouride release
  • Improved aesthetics

Question 3. Composition of GIC.

Answer:

Composition of GIC:

Powder:

  • Silica-41.9%
  • Alumina-28.6%
  • Aluminium fluoride-1.6%
  • Calcium fluoride-15.7%
  • Sodium fluoride- 9.3%
  • Aluminum phosphate- 3.8%

Liquid:

  • Polyacrylic acid with copolymers with itaconic acid, maleic acid, and tricarballylic acid
  • Tartaric acid
  • Water

Glass Ionomer Cement Viva Voce

  1. Varnishes or sealers should not be used to coat dentin if GIC is to be used as a restorative material
  2. GIC adhesion is achieved partly by mechanical adhesion and partly by chemical chelation
  3. To increase mechanical strength, GIC used as restoration are mixed at a higher powder-liquid ratio
  4. After 24 hours the pH of GIC is 5.3
  5. To increase the pH of GIC, zinc oxide is incorporated in the powder
  6. Glass ionomers bond best to enamel than dentin and cementum
  7. GIC shows decreasing levels of fluoride release with time
  8. Powder of GIC is referred to as “ion-leachable glass”

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