Glass Ionomer Restorations Overview
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Questions and Answers

What is a significant advantage of using the open sandwich technique in deep Class II preparations?

  • Enhanced aesthetics compared to traditional methods
  • Lower cost of composite materials
  • Simplified bonding process with no acid etching required
  • Greater resistance to microleakage and caries at dentin margins (correct)

    • Which of the following statements about the use of GIC is accurate?

  • GIC is less biocompatible than composite resins
  • GIC can cause significant postoperative sensitivity
  • GIC requires extensive acid etching to bond effectively
  • GIC releases fluoride, offering additional protective benefits (correct)

    • What is a disadvantage of the open sandwich technique?

  • Reduces bulk and minimizes polymerization shrinkage
  • High technique sensitivity and time consumption (correct)
  • Eliminates the need for dentin bonding agents
  • Requires fewer composite resin increments during application

    • During the clinical steps, what is the purpose of conditioning the prepared tooth with polyacrylic acid?

    <p>To achieve optimal adhesion of GIC</p> Signup and view all the answers

    What is necessary if the GIC restoration has matured over time?

    <p>The GIC surface must be acid etched for better adhesion</p> Signup and view all the answers

    What was the primary motivation behind the invention of Glass Ionomer Cements (GIC)?

    <p>To create a hybrid of dental silicate and zinc polycarboxylate cements.</p> Signup and view all the answers

    Which additive in the GIC liquid serves to improve handling characteristics and extend working time?

    <p>Tartaric acid</p> Signup and view all the answers

    What is one major advantage of resin-modified glass ionomer cements (RMGIC)?

    <p>Improved aesthetics</p> Signup and view all the answers

    During which phase of the setting reaction does the polyacid attack the glass particles?

    <p>Ion Leaching Phase</p> Signup and view all the answers

    What components primarily make up RMGIC?

    <p>80% GIC and 20% light-cured methacrylates</p> Signup and view all the answers

    What role does water play during the setting of Glass Ionomer Cements?

    <p>It acts as a hydration agent while also being the initial reaction medium.</p> Signup and view all the answers

    Which of the following options is a function of calcium ions during the setting of GIC?

    <p>They create a gel-like structure with embedded glass particles.</p> Signup and view all the answers

    What is the main purpose of using polyacrylic acid in the preparation of RMGIC?

    <p>To enhance chemical adhesion to tooth structure</p> Signup and view all the answers

    What is one disadvantage of resin-modified glass ionomer cements?

    <p>Shrinkage during setting</p> Signup and view all the answers

    Which property of GIC is enhanced by additives like lanthanum, strontium, and barium?

    <p>Radiopacity</p> Signup and view all the answers

    What are the clinical steps to improve the adhesion of glass ionomer cements?

    <p>Conditioning the prepared surface with various agents</p> Signup and view all the answers

    What is a key advantage of using highly viscous glass ionomers for dental restorations?

    <p>They have low solubility in oral fluids.</p> Signup and view all the answers

    What notice should clinicians make about freshly mixed cements exposed to air?

    <p>They may craze and crack due to desiccation.</p> Signup and view all the answers

    How long should finishing and polishing of GIC typically be delayed after placement?

    <p>24 hours</p> Signup and view all the answers

    What is the final phase in the setting reaction of Glass Ionomer Cements?

    <p>Polysalt Gel Phase</p> Signup and view all the answers

    Which factor limits the aesthetic appeal of glass ionomer cements compared to composites?

    <p>Opaqueness</p> Signup and view all the answers

    What is the nature of the setting reaction for RMGIC?

    <p>A combination of acid-base reaction and resin polymerization</p> Signup and view all the answers

    What is a potential limitation when using glass ionomer cements during their setting phase?

    <p>Susceptibility to moisture</p> Signup and view all the answers

    What innovation was introduced by GC Corporation in 2014 regarding glass-hybrid technology?

    <p>Stress-bearing Class II restorations</p> Signup and view all the answers

    Which form of RMGIC is NOT commonly used?

    <p>Liquid-only system</p> Signup and view all the answers

    How can the strength of GICs be enhanced?

    <p>By modifying the chemical composition of the original glass powder</p> Signup and view all the answers

    What is a characteristic of the EQUIA Forte® HT Fil launched in 2019?

    <p>It has low early moisture sensitivity.</p> Signup and view all the answers

    What mechanism primarily facilitates the adhesion of glass-ionomer cements to the tooth surface?

    <p>Formation of hydrogen bonds between carboxyl groups and bound water</p> Signup and view all the answers

    What is a common method for enhancing the flexural strength of reinforced glass ionomer cements?

    <p>Incorporating alumina or glass fibers</p> Signup and view all the answers

    Which glass ionomer cement combines amalgam alloy powders with GIC to enhance its properties?

    <p>Miracle mix</p> Signup and view all the answers

    Which type of glass-ionomer cement is specifically categorized as a restorative material for aesthetic purposes?

    <p>Type II</p> Signup and view all the answers

    What concentration of aqueous fluoride is effective enough to inhibit fluoride-resistant Streptococcus mutans bacteria?

    <p>600 ppm</p> Signup and view all the answers

    What is a key advantage of glass-ionomer cements compared to other types of dental cements?

    <p>Chemical adhesion to tooth structure through ion exchange</p> Signup and view all the answers

    Which classification of glass-ionomer cements is designed for use as a liner or base?

    <p>Type III</p> Signup and view all the answers

    Which of the following is an indication for using glass-ionomer cements?

    <p>Restoration of root caries</p> Signup and view all the answers

    What is the primary chemical interaction involved in the adhesion of glass-ionomer cements to the enamel and dentin?

    <p>Chemical bonding with calcium ions on the tooth surface</p> Signup and view all the answers

    What potential benefit does fluoride release from glass-ionomer cements provide?

    <p>Prevents demineralization of dentin</p> Signup and view all the answers

    What is the primary reason for protecting newly placed GIC restorations immediately after matrix removal?

    <p>To prevent water exchange and sensitivity</p> Signup and view all the answers

    Which of the following teeth is a tunnel preparation recommended for?

    <p>Deciduous teeth or geriatric patients' mobile teeth</p> Signup and view all the answers

    What is the correct angle for penetrating the occlusal surface using a round bur in a tunnel preparation?

    <p>45°</p> Signup and view all the answers

    Which equipment is NOT specifically mentioned as a method to protect GIC restorations?

    <p>Ethanol</p> Signup and view all the answers

    What does the Atraumatic Restorative Treatment (ART) primarily involve?

    <p>Hand instruments and high-viscosity GIC for restoration</p> Signup and view all the answers

    In the sandwich technique, which material is used to replace dentin?

    <p>High-viscosity GIC</p> Signup and view all the answers

    During the tunnel preparation, what should be done after removing caries and before applying the matrix band?

    <p>Use a periodontal probe to measure lesion depth</p> Signup and view all the answers

    What is the primary advantage of using the sandwich technique in restorations?

    <p>Combines the properties of glass ionomer and composite resin</p> Signup and view all the answers

    Study Notes

    Glass Ionomer Restorations

    • Glass ionomer cements (GIC) were introduced in 1972, marketed in Europe in 1975, and in the US in 1977.
    • GICs are a hybrid of silicate cements and zinc polycarboxylate cements.
    • GICs use organic chelating acids instead of phosphoric acid in dental silicate cements.
    • GIC powder is primarily an acid-soluble calcium fluoroaluminosilicate glass, similar to silicate glass but with a higher alumina-silicate ratio to enhance its reactivity.
    • GIC liquid is an aqueous solution of polymers and copolymers of acrylic acid, and includes itaconic and tricarboxylic acids to decrease viscosity and promote glass-liquid reactivity.
    • Tartaric acid also increases handling time though accelerates setting time.
    • Raw material percentages in GIC powder: silica (41.9%), alumina (28.6%), aluminum fluoride (1.6%), calcium fluoride (15.7%), sodium fluoride (9.3%), and aluminum phosphate (3.8%).
    • Liquid composition: polyacrylic acid (40-55%), maleic acid (6-15%), tartaric acid (30%), and water.
    • Setting reaction is an acid-base interaction between the acidic polyelectrolyte and aluminosilicate glass, occurring in three phases.

    Ion Leaching Phase

    • This phase begins when the powder and liquid are mixed, releasing ions, like Ca2+ and Al3+, from the glass particles.

    Hydrogel Phase

    • Calcium ions released rapidly react with the polyacrylic acid, forming calcium bridges and a calcium polycarboxylate gel.
    • Water acts as the initial reaction medium and hydrates the crosslinked agents to form a stable gel structure, creating moisture resistance.

    Polysalt Phase

    • Hydrogen ions continue to attack the glass, releasing Al ions as AlF ions, forming a water-insoluble Ca-Al-carboxylate gel.
    • This Ca-Al-carboxylate gel strengthens the cement.

    Clinical Tips

    • Freshly mixed GIC should be protected from air exposure to prevent desiccation and cracking.
    • Water contamination during this stage can lead to matrix dissolution and release of ions.

    Adhesion

    • Proper wetting of the tooth surface facilitates GIC adhesion due to the hydrophilic nature of both the cement and the tooth surface.
    • Hydrogen bonds form between the free carboxyl groups of the cement and bound water on the tooth surface.
    • A chemical bond forms between carboxylate groups and calcium ions, further enhancing adhesion.

    Fluoride Release

    • Fluoride released from GIC penetrates deeply into demineralized dentin at concentrations of about 5000 ppm.
    • Concentrations as low as 600 ppm inhibit fluoride-resistant Streptococcus mutans bacteria.

    Classification of GICs

    • GICs are categorized based on use/application and clinical use. Specific Type I-VI classifications categorized by luting cements, restorative cements, liners, bases, fissures, sealants, orthodontic, and core build-up applications,
    • Various classes exist: Type I-Luting, Type II-Restorative, Type III-Liner-base, Type I-luting, Type II-restorative, Type III-liners/bases, Type IV-fissure sealants, Type V-orthodontic, Type VI-core build up

    Indications of GICs

    • Restoration of permanent teeth (Class V, Class III, Class I-tooth preparations, abrasions, erosions, root caries)
    • Restoration of deciduous teeth (Class I, Class VI-tooth prep, rampant caries, nursing bottle caries)
    • Luting/cementing (metal/nonmetal restorations, inlays, onlays, crowns, pins, posts orthodontic bonding, brackets)
    • Preventive restorations (tunnel prep, pit and fissure sealants)
    • Protective liner under composite/amalgam
    • Bonding agent
    • Dentin substitute
    • Core build-up

    Advantages of GIC

    • Inherent adhesion to tooth enamel and dentin through ion exchange.
    • Biocompatibility due to large-sized polyacrylic acid molecules.
    • Minimal shrinkage and good marginal seal.
    • Anticariogenic properties due to fluoride release, easily replenished through fluoride applications.
    • Requires minimal tooth preparation, use on children.
    • Less technique-sensitive than composite resins.

    Disadvantages of GIC

    • Lower compressive strength than amalgam/resin composites.
    • Reduced wear resistance.
    • Susceptible to water during setting, impacting physical properties and aesthetics.
    • Opaque, reducing aesthetic appeal compared to composites.
    • Requires moisture control during manipulation and application.
    • Technique sensitivity and time-consuming method

    High Viscosity Conventional GICs

    • Benefit in atraumatic restorative treatment, using high-viscosity GICs as an alternative to amalgam.
    • Allows for using higher powder-liquid ratios in the cement.

    Glass Hybrids

    • Introduced in 2014 as EQUIA Forte, the first glass-hybrid technology for stress-bearing Class II restorations.
    • Introduced in 2019 as EQUIA Forte HT, enhanced translucency and suitable for stress-bearing and non-stress-bearing Class I, II, and V restorations.
    • Reinforced with ultrafine glass particles and optimized polyacrylic acid, resulting in excellent mechanical properties.

    Reinforced GICS

    • Enhancing GIC strength via modifying the chemical composition of the original glass powder.

    Disperse-phase Glasses

    • Strengthening is improved by incorporating corundum and tielite crystallites.

    Fiber-reinforced Glasses

    • Strength is enhanced through the addition of alumina, glass, silica, and carbon fibers.

    Metal-reinforced GICs

    • Notable examples include "Miracle Mix," combining amalgam alloy powders with GIC to improve flexural strength.

    Cermet Cements

    • Sintering metal and glass powders creates strong bonds, thus improving resistance to abrasion and flexural strength.

    Resin-Modified GICs (RMGICs)

    • Introduced in 1988 to address limitations of conventional GICs, improved by including resin.
    • Resin bonding to tooth structure occurs via micromechanical and chemical mechanisms, forming ionic bonds with enamel and dentin.
    • RMGIC typically comprises approximately 80% GIC components.

    RMGIC Advantages

    • Extended working time, controlled setting.
    • Good adaptation, chemical adhesion to enamel and dentin
    • Fluoride release, improved aesthetics, superior strength characteristics.

    RMGIC Disadvantages

    • Shrinkage during setting, limited depth of cure.

    Forms of RMGIC

    • Powder and liquid form.
    • Capsules with premeasured powder and liquid components.
    • Paste dispensing systems.

    GIC Setting Reaction

    • Combined slow acid-base reaction and resin polymerization.
    • Dual mechanism is chemically induced and completed by light.

    Clinical Steps: GIC Application

    • Conditioning of the preparation surface using a polyacrylic acid to increase adhesion.
    • Restorative procedures, using a carrier to optimally place and minimize voids in the prep.
    • Remove excess, shape/contouring is completed.
    • Photoactivation using light curing is used if needed for light-cured GICs.
    • Finishing and polishing are delayed for at least 24-hours to allow for ionic equilibrium with the surrounding environment, protecting from moisture contamination/desiccation.

    Surface Protection (GICs)

    • GICs are sensitive to moisture contamination and surface desiccation.
    • Resin bonding agents, cocoa butter, petroleum jelly, and varnishes protect the restoration after matrix removal.

    Tunnel GIC Restoration

    • Tunnel preparation removed proximal caries, preserving the marginal ridge.
    • Deciduous teeth and mobile/geriatric teeth, suitable for incipient proximal lesions in posterior teeth in patients with low caries.
    • Clinical steps are: assess caries, bitewing x-ray, isolate/dry tooth, place a wedge in the preparation.

    Atraumatic Restorative Treatment (ART)

    • Removing carious lesions with hand instruments (spoon excavators) and restoring with high-viscosity GICs.

    Sandwich Technique

    • A laminated restoration utilizing glass ionomer (to replace dentin) and composite resin (enamel for cervical margins).
    • Advantages: Strength, aesthetics, finish of composite resins, fluoride release from GIC, reduced composite bulk, reduces polymerization shrinkage, eliminates need for acid etching of dentin. Avoiding postoperative sensitivity.

    Sandwich Technique Disadvantages

    • Technique sensitive, time-consuming

    Clinical Steps Overview: Sandwich Technique

    • Isolate, tooth preparation with cavity prep involving dentin butt junction.
    • Condition the dentin prep using polyacrylic acid
    • Fill the cavity with fast-setting GIC.
    • Acid etching is only required for immature or longer-time-in-place GICs as a washout of matrix around filler particles creating a rough surface.
    • Apply dentin bonding agent, cure for 20 seconds
    • Place composite and cure according to manufacturer's guidelines.

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    Glass Ionomer Restorations PDF

    Description

    Explore the fundamentals of Glass Ionomer Cements (GIC), their introduction, composition, and unique properties. This quiz will test your understanding of the material's history and chemical composition, as well as its applications in dentistry. Ideal for dental students and professionals looking to reinforce their knowledge of GICs.

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