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Questions and Answers
What is the principal constituent of Zinc Phosphate Cement?
What is the principal constituent of Zinc Phosphate Cement?
What type of reaction occurs during the setting of Zinc Phosphate Cement?
What type of reaction occurs during the setting of Zinc Phosphate Cement?
Which factor does NOT influence the setting reaction of Zinc Phosphate Cement?
Which factor does NOT influence the setting reaction of Zinc Phosphate Cement?
What effect does heat have on the setting rate of Zinc Phosphate Cement?
What effect does heat have on the setting rate of Zinc Phosphate Cement?
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What is the purpose of incorporating Zn ± Al phosphates in the cement?
What is the purpose of incorporating Zn ± Al phosphates in the cement?
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What defines the consistency of the Zinc Phosphate Cement mix?
What defines the consistency of the Zinc Phosphate Cement mix?
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In the manipulation of Zinc Phosphate Cement, what tool is typically used to mix the material?
In the manipulation of Zinc Phosphate Cement, what tool is typically used to mix the material?
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What is the pH level of the setting cement during the initial phase?
What is the pH level of the setting cement during the initial phase?
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What is a characteristic of orthodontic luting agents?
What is a characteristic of orthodontic luting agents?
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Which type of glass ionomer cement is used for cementation of orthodontic appliances?
Which type of glass ionomer cement is used for cementation of orthodontic appliances?
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What is a common property of endodontic obturation materials like Ketac-Endo?
What is a common property of endodontic obturation materials like Ketac-Endo?
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How do RMGI materials behave over time in terms of hydroscopic expansion?
How do RMGI materials behave over time in terms of hydroscopic expansion?
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Which of the following is NOT a guideline for using orthodontic luting agents?
Which of the following is NOT a guideline for using orthodontic luting agents?
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What is the main purpose of Type 1 cements in dental applications?
What is the main purpose of Type 1 cements in dental applications?
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Which type of restorative cement is reinforced and includes condensable and metal-modified options?
Which type of restorative cement is reinforced and includes condensable and metal-modified options?
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What distinguishes resin-modified glass ionomer (RMGI) from conventional glass ionomer?
What distinguishes resin-modified glass ionomer (RMGI) from conventional glass ionomer?
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Which of the following is an example of a conventional luting cement?
Which of the following is an example of a conventional luting cement?
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What type of cements are used as liners, bases, and sealants?
What type of cements are used as liners, bases, and sealants?
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What is one of the potential causes of initial post-operative sensitivity with luting cements?
What is one of the potential causes of initial post-operative sensitivity with luting cements?
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Which of the following statements is true regarding clinical studies of sensitivity with conventional glass ionomer cements?
Which of the following statements is true regarding clinical studies of sensitivity with conventional glass ionomer cements?
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Which type of cement is specifically categorized as a pediatric glass ionomer cement?
Which type of cement is specifically categorized as a pediatric glass ionomer cement?
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What is a disadvantage of Zinc Polycarboxylate Cement?
What is a disadvantage of Zinc Polycarboxylate Cement?
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Which of the following properties is NOT associated with Glass Ionomer Cement?
Which of the following properties is NOT associated with Glass Ionomer Cement?
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What is one of the major components of conventional Glass Ionomer Cement?
What is one of the major components of conventional Glass Ionomer Cement?
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Which type of Cement is the first commercial product that combined glass and polyacrylic acid?
Which type of Cement is the first commercial product that combined glass and polyacrylic acid?
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What setting time range does conventional Glass Ionomer Cement have?
What setting time range does conventional Glass Ionomer Cement have?
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Which aspect is improved in Resin-Modified Glass Ionomers compared to traditional Glass Ionomers?
Which aspect is improved in Resin-Modified Glass Ionomers compared to traditional Glass Ionomers?
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What is a characteristic of Resin-Modified Glass Ionomers?
What is a characteristic of Resin-Modified Glass Ionomers?
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Which of the following indicates a contraindication for using Glass Ionomer Cement?
Which of the following indicates a contraindication for using Glass Ionomer Cement?
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What characteristic does not apply to conventional Glass Ionomer Cement's setting reaction?
What characteristic does not apply to conventional Glass Ionomer Cement's setting reaction?
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What is a major modification made to improve the handling of Glass Ionomer Cement?
What is a major modification made to improve the handling of Glass Ionomer Cement?
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Which type of cement is known to have a short working time of approximately 2.5 minutes?
Which type of cement is known to have a short working time of approximately 2.5 minutes?
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What is the expected outcome of fluoride release from Glass Ionomer materials?
What is the expected outcome of fluoride release from Glass Ionomer materials?
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What does the presence of stannous fluoride in Zinc Polycarboxylate Cement relate to?
What does the presence of stannous fluoride in Zinc Polycarboxylate Cement relate to?
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Why is adherence to tooth structure an important characteristic of Glass Ionomer Cement?
Why is adherence to tooth structure an important characteristic of Glass Ionomer Cement?
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What is the typical powder:liquid ratio range for esthetic restorative cements?
What is the typical powder:liquid ratio range for esthetic restorative cements?
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Which type of glass ionomer cement is best suited for areas where appearance is not a primary concern?
Which type of glass ionomer cement is best suited for areas where appearance is not a primary concern?
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What should be done to the tooth before applying esthetic restorative materials?
What should be done to the tooth before applying esthetic restorative materials?
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What is the significance of using a polyacrylic-acid conditioner in conditioning dentin?
What is the significance of using a polyacrylic-acid conditioner in conditioning dentin?
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Which of the following types of esthetic restoratives is moisture-sensitive?
Which of the following types of esthetic restoratives is moisture-sensitive?
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What is a key feature of metal-modified glass ionomers?
What is a key feature of metal-modified glass ionomers?
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What is essential for finishing conventional glass ionomer restoratives?
What is essential for finishing conventional glass ionomer restoratives?
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In what application are Type 3 glass ionomer cements primarily used?
In what application are Type 3 glass ionomer cements primarily used?
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What is one of the requirements for Type II (i) glass ionomers in anterior repairs?
What is one of the requirements for Type II (i) glass ionomers in anterior repairs?
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Which of the following examples represents a reinforced restorative?
Which of the following examples represents a reinforced restorative?
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What is the effect of desiccation on setting cement during the finishing process?
What is the effect of desiccation on setting cement during the finishing process?
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What should be considered when using RMGI versions of restoration materials in pediatric dentistry?
What should be considered when using RMGI versions of restoration materials in pediatric dentistry?
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What is a recommended surface protection method for common esthetic restoratives?
What is a recommended surface protection method for common esthetic restoratives?
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Study Notes
Zinc Phosphate Cement
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Composition:
- Powder: Zinc Oxide (ZnO) as primary constituent, and Magnesium Oxide (MgO), Silica (SiO2), Bismuth Oxide (Bi2O3).
- Liquid: Aqueous Phosphoric acid (30-40 % H2O) and Zinc/Aluminum phosphates to slow setting reaction.
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Setting Reaction:
- ZnO reacts with Phosphoric Acid (H3PO4) producing Zinc Phosphate (Zn3(PO4)2) and water.
- Surface of ZnO dissolves in the acid producing an insoluble Phosphate.
- Cement is heterogeneous containing unreacted ZnO core surrounded by a Zinc Phosphate matrix.
- Reaction is exothermic, initial low acidity pH 3-4 can irritate the pulp.
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Manipulation:
- Powder/liquid ratio, rate of addition, moisture, and temperature all affect setting reaction.
- Typically dispensed as scoops of powder and drops of liquid.
- Mix using a cement spatula and glass slab.
- Consistency can be modified for different clinical uses;
- Thin mix (low powder/liquid ratio) for luting.
- Thicker mix (high powder/liquid ratio) for base.
- Setting reaction is exothermic, so heat accelerates the rate.
- Dissipate heat by:
- Incremental powder addition.
- Mixing slowly over a large area of chilled glass slab.
- Cooled glass slab absorbs heat.
Zinc Polycarboxylate Cement
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Advantages:
- Kind to pulp.
- Chemical adhesion.
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Disadvantages:
- Short working time (2.5 minutes).
- Contains: Up to 4% stannous fluoride.
- Doesn't have anti-cariogenic properties: Releases about 10% of the fluoride compared to GIC.
Glass Ionomer Cement
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Early Developers:
- Wilson and Kent in the United Kingdom (1972).
- First commercial product was ASPA (alumino-silicate polyacrylic acid).
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Advantages:
- Inherent (chemical) adhesion to tooth structure.
- Fluoride release.
- Coefficient of thermal expansion (CTE) similar to tooth structure.
- Biocompatible.
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Disadvantages:
- Susceptible to moisture and desiccation.
- Low fracture toughness.
- Low flexural strength.
- Low wear resistance.
- Relatively poor esthetics.
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Indications:
- Direct restorative, e.g., Class V, root caries, Class III, pediatric dentistry (resin-modified versions), tunnel preparations, and atraumatic restorative treatment (ART).
- Luting agents.
- Bases (liners).
- Caries control.
- Core block-out.
- Occlusal sealant.
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Contraindications:
- Stress-bearing areas in permanent teeth (Class I, II, and IV).
Conventional GIC
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Composition:
- Powder: Ion-leachable calcium aluminofluorosilicate glass.
- Liquid: Copolymers of acrylic acid and/or water (copolymers freeze-dried, placed in powder for maximum shelf-life).
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Ion-leachable glass:
- Silicon dioxide (SiO2).
- Aluminum oxide (Al2O3).
- Calcium fluoride (CaF2).
- Aluminum phosphate (AlPO4).
- Sodium fluoride (NaF).
- Aluminum fluoride (AlF3).
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Polyacids:
- Acrylic acid.
- Maleic acid.
- Itaconic acid.
- Tricarboxylic acid.
- Tartaric acid: improves handling, extends working time, sharpens set, increases strength.
Setting Reaction (Conventional)
- Complex acid-base reaction: glass (basic) + polyacid form a salt hydrogel.
- Three phases:
- Ion-Leaching Phase: acid attacks glass, releasing aluminum, calcium, and fluoride ions to form complexes and a hydrogel around the glass particles. Early on, calcium ions dominate. NaF is formed but doesn't affect physical properties.
- Hydrogel Phase: calcium and aluminum poly salts cross-link polymer chains, increasing viscosity and hardening, leading to poor initial physical properties and vulnerability to moisture. Protection with bonding agent is necessary.
- Polysalt-Gel Phase: slow maturation of matrix, aluminum polyacrylate polymers dominate, becoming stronger and less soluble, but saturation can take six months to a year. Late stage is susceptible to dehydration, and protection with bonding agent is necessary.
Resin-Modified GIC (RMGI)
- First developed as liners.
- Modified with light- and/or chemically-activated methacrylate side chains on polyacrylic acid molecules, often with HEMA.
- Total resin in the set material is 4.5-6%.
- Attempt to combine benefits of glass ionomer (fluoride release, adhesion) and composite resin (strength, esthetics).
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Composition: Same as conventional GIC, but with additional components:
- Liquid: Contains initiators and copolymers of acrylic acid with grafted methacrylate groups or HEMA.
- Setting Reaction: Traditional acid-base reaction, similar to conventional GIC, proceeds more slowly, but also a free-radical polymerization takes place (light or chemical cure, similar to composites) forming a cross-linked resin-reinforced matrix.
Free-Radical Polymerization
- Visible light initiation: Camphorquinone (absorbs blue light) reacts with an amine activator.
- Chemical initiation: separate pastes containing a benzoyl peroxide initiator and tertiary-amine activator are mixed. This forms free radicals that initiate addition polymerization of methacrylates (grafted and/or free), including HEMA.
Material-Related Variables
- Fluoride Release:
- Rapid initial release from matrix.
- Slow, long-term release from particles.
- Fluoride does not participate in matrix formation and doesn't affect physical properties.
- Amount of release is similar for both conventional and RMGI.
- Adhesion:
- Conventional GIC: Ion exchange between carboxyl groups of GIC and Ca+2 of hydroxyapatite in tooth.
- RMGI: Similar ion exchange, but also a resin-impregnated hybrid layer.
- Pulpal response: The text does not mention specific information about pulpal response.
- Physical properties: The text does not mention specific information about physical properties.
Glass Ionomer Cement Types
- Type 1: Luting cement for bonding crowns, bridges, inlays, onlays, and orthodontic appliances.
- Type 2: Restorative cement, used for esthetic and reinforced restorations.
- Type 3: Liners and bases, for sealing and protecting dentin.
Glass Ionomer Cement Applications
- Traditional Acid-Base: Conventional Glass Ionomer Cement (GIC)
- Light- and/or Chemical-Cure: Resin-Modified Glass Ionomer Cement (RMGI)
Luting Cements (Type 1)
- Conventional Type 1 GIC Examples: Ketac-Cem (3M ESPE), Fuji 1 (GC)
- RMGI Type 1 Examples: Fuji Plus and FujiCem (GC), Rely X (3M ESPE)
- RMGI Benefits: Greater strength, less moisture sensitivity, and less soluble.
Post-Op Sensitivity
- Initial reports of sensitivity with GIC were related to low acidity and improper handling.
- Clinical studies show no increase in sensitivity when GIC is properly used.
- No difference in post-op sensitivity was observed between: Conventional GIC vs. Zinc Phosphate, Conventional GIC vs. RMGI.
RMGI Luting Cement Hydroscopic Expansion
- Hydroscopic Expansion: Expansion in the presence of moisture, which can pose issues for restorations.
- Follow Manufacturer Recommendations: Minimize risk of hydroscopic expansion.
Orthodontic Luting Agents
- Fluoride-releasing: Reduces the occurrence of white spot lesions.
- Bonds in a moist environment.
- Etch optional (surface conditioning).
- Examples: Fuji Ortho (GC), Fuji Ortho LC (GC)
Endodontic Obturation
- Fluoride-releasing: Protects against secondary caries.
- Radiopaque: Visible on x-ray.
- Short working time.
- More difficult to retreat.
- Example: Ketac-Endo (3M EPSE)
Esthetic Restorative Cements (Type 2)
- Conventional Examples: Ketac-Fil (3M ESPE), Fuji II (GC), Glasionomer Type II (Shofu)
- RMGI Examples: Fuji II LC (GC), Vitremer (3M ESPE), Riva Light Cure (SDI)
Esthetic Restorative Case Selection
- High caries risk patients.
- Areas of lower stress (Class III & V restorations).
- Pediatric dentistry (RMGI is preferred).
Esthetic Restorative Techniques
- Surface must be clean.
- Remove the smear layer.
- Tooth must be moist.
Esthetic Restorative Dentin Conditioning
- Conventional GIC: Polyacrylic-acid conditioner removes the smear layer, cleans the surface, and promotes adhesion.
- RMGI: Follow manufacturer instructions (may use polyacrylic-acid conditioner or an adhesive).
Esthetic Restorative Moisture Content
- GIC is "moisture-sensitive" due to its ion exchange in a hydrated medium.
- Desiccation (removing moisture) can extract water from the cement.
- Excess water dilutes the cement matrix.
Esthetic Restorative Finishing
-
Conventional GIC:
- Surface coat is applied.
- Wait 15 minutes before finishing.
- Minimize trauma to the surface (use blades and slow speeds).
-
RMGI:
- Surface coat is applied.
- Finishing occurs immediately.
- Gentle techniques with fine diamonds and polishing discs.
Esthetic Restorative Surface Protection
- Protect setting cement from early moisture contamination and later desiccation.
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Unfilled resins: Essential for conventional GIC; optional for RMGI.
- Improve water resistance.
- Fill irregularities.
- Enhance color stability.
- Reduce fluoride release.
Esthetic Restorative RMGI Liners
- "Open-Sandwich" technique: Use of RMGI liners with posterior composite restorations to reduce leakage and gaps, especially at dentinal gingival margins.
- Examples: Fuji II LC (GC), Vitremer (3M ESPE)
Reinforced Restorative Cements (Type 2)
- Condensable: Conventional GIC that is easier to handle.
- Metal-Modified: Conventional GIC with added metal for improved properties.
Condensable Restorative Cements (Type 2)
- Indications: Provisionalization, pediatric restorations, Atraumatic Restorative Treatment (ART).
- Examples: Fuji IX (GC), Ketac-Molar (3M ESPE)
Metal-Modified Glass Ionomers (Type 2)
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Conventional GIC with Added Metal:
- Silver fused with powder: Ketac-Silver (3M ESPE).
- Amalgam alloy mixed with powder: Miracle-Mix (GC).
- Benefits: Improved handling, radiopacity, wear resistance, and similar or slightly less fluoride release.
- Indications: Non-stress bearing areas, core build-ups, caries control, provisionals, Atraumatic Restorative Treatment (ART).
Liners (Type 3)
- Conventional Examples: Ketac-Bond (3M ESPE), Lining Cement (GC).
- RMGI Examples: Vitrebond (3M ESPE), Fuji Lining LC (GC).
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Description
This quiz covers the composition, setting reaction, and manipulation techniques of Zinc Phosphate Cement. It details the chemical reactions involved and the factors affecting its setting process, making it crucial for dental applications. Test your understanding of this key material in restorative dentistry.
