Dental Cements: Uses and Requirements
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What is the primary advantage of indirect pulp capping?

  • It uses only resin-based materials for protection.
  • It places the pulp capping material directly on the pulp.
  • It allows the remaining dentin to induce new dentin formation. (correct)
  • It completely removes all soft dentin to prevent infection.

    • In which situation is direct pulp capping most appropriately used?

  • When the pulp is exposed during tooth preparation. (correct)
  • For teeth with deep caries.
  • To treat a tooth with chronic pulpitis.
  • When there is no exposure of the pulp.

    • What is a common material used for direct pulp capping?

  • Calcium hydroxide (correct)
  • Amalgam
  • Zinc polycarboxylate
  • Silicate cement

    • Which of the following cements is associated with a sedative effect on the pulp?

    <p>Zinc oxide eugenol cement</p> Signup and view all the answers

    What type of dental cement is made from a mixture of alumino-silicate glass powder with polyacrylic acid?

    <p>Glass ionomer cement</p> Signup and view all the answers

    What does the varnish create at the restoration-tooth interface?

    <p>A thin film that minimizes penetration of oral fluids.</p> Signup and view all the answers

    What is a characteristic property of cements based on eugenol ?

    <p>Their sedative effect.</p> Signup and view all the answers

    What is a key factor in deciding to use indirect pulp capping?

    <p>Presence of a thin layer of dentin covering the pulp.</p> Signup and view all the answers

    What is the main chemical reaction that initiates the setting of conventional zinc oxide eugenol cement?

    <p>Zinc oxide undergoes hydrolysis in the presence of water.</p> Signup and view all the answers

    Which of the following properties of zinc oxide eugenol cements is related to its effect on pulp in deep cavities?

    <p>The pH is about 7, reducing adverse effects on the pulp.</p> Signup and view all the answers

    In which application is zinc oxide eugenol cement NOT typically used?

    <p>Permanent restorative material.</p> Signup and view all the answers

    How does the presence of eugenol in zinc oxide eugenol cement affect bonding with resin composite materials?

    <p>It inhibits the setting of resin composite restorative materials.</p> Signup and view all the answers

    Which component is primarily responsible for reducing the brittleness of conventional zinc oxide eugenol cement?

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

    What is the primary advantage of polymer-reinforced zinc oxide eugenol cements?

    <p>Greater compressive strength compared to standard formulation.</p> Signup and view all the answers

    What is the typical ratio of powder to liquid used when mixing conventional zinc oxide eugenol cement?

    <p>3:1</p> Signup and view all the answers

    What is a characteristic feature of zinc oxide eugenol cement's mechanical properties?

    <p>Poor compressive strength of about 15 MPa.</p> Signup and view all the answers

    Which property of dental cements ensures the visibility of the cement layer in X-rays?

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

    What is the main function of pulp capping materials?

    <p>To protect the pulp from thermal injuries and chemical irritants</p> Signup and view all the answers

    Which type of pulp capping is indicated when the pulp is still healthy and remains exposed?

    <p>Direct pulp capping</p> Signup and view all the answers

    Which of the following best describes indirect pulp capping?

    <p>It is performed when the pulp is viable, but the dentin is significantly demineralized.</p> Signup and view all the answers

    What distinguishes zinc oxide eugenol from other dental cements?

    <p>Its ability to promote healing and provide antibacterial effects</p> Signup and view all the answers

    Which feature is NOT a requirement for dental cements?

    <p>Ability to chemically bond with metallic restorations</p> Signup and view all the answers

    What is the recommended film thickness for a luting agent to ensure proper seating of restorations?

    <p>25 µm or less</p> Signup and view all the answers

    What is the primary setting reaction of resin modified glass ionomer cements?

    <p>Free radical polymerization reaction of the resin component</p> Signup and view all the answers

    Which property is significantly improved in metal reinforced glass ionomer cements compared to traditional glass ionomer?

    <p>Abrasion resistance</p> Signup and view all the answers

    What leads to the gloss in a properly mixed glass ionomer material?

    <p>Presence of unreacted polyacrylic acid</p> Signup and view all the answers

    What is a common disadvantage associated with the use of metal reinforced glass ionomer cements?

    <p>Reduced bonding strength with tooth structures</p> Signup and view all the answers

    What aspect of glass ionomer cement distinguishes it in terms of biological effect?

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

    Which manipulation technique should be avoided to prevent discoloration when mixing powder into liquid?

    <p>Using a stainless steel spatula</p> Signup and view all the answers

    Which of the following is NOT a characteristic of hybrid ionomers?

    <p>Incorporation of metal alloys for strength</p> Signup and view all the answers

    What type of reaction does the resin part of Tricure glass ionomer undergo in the absence of light?

    <p>Only chemical cure polymerization</p> Signup and view all the answers

    Which property of resin modified glass ionomer cement makes it particularly effective in dental applications?

    <p>Ability to release fluoride</p> Signup and view all the answers

    What is a key aspect of the bonding mechanism employed by adhesive resin cements?

    <p>Chemical bonding</p> Signup and view all the answers

    In dual cured resin cements, what occurs simultaneously when the cement is mixed and then exposed to light?

    <p>Both chemical activation and light polymerization occur at the same time</p> Signup and view all the answers

    Which of the following fillers in nanoionomer cements enhances their mechanical properties?

    <p>Fluoroaluminosilicate glass</p> Signup and view all the answers

    Which of the following characterizes the manipulation technique for self-cured resin cements?

    <p>Requires a dual paste system</p> Signup and view all the answers

    What advantage does resin modified glass ionomer cement have against environmental factors?

    <p>High resistance to desiccation and acid attack</p> Signup and view all the answers

    What defines the composition difference between light cured and dual cured resin cements?

    <p>Dual cured requires both light and chemical curing agents</p> Signup and view all the answers

    What ions are primarily released during the setting reaction of glass ionomer cement when the acid in the liquid attacks the glass particles?

    <p>Ca2+, Al3+, and F-</p> Signup and view all the answers

    What is the role of tartaric acid in the composition of glass ionomer cement?

    <p>Decreases setting time and increases working time</p> Signup and view all the answers

    Which factor contributes to the strength of glass ionomer cement, particularly in relation to aluminum ions?

    <p>Al3+ migrates slower than Ca2+ during the setting reaction</p> Signup and view all the answers

    What happens to the surface of the glass particles when the acid in the liquid interacts with glass ionomer cement components?

    <p>It dissolves the particles, releasing various ions</p> Signup and view all the answers

    What is the primary manipulation technique used for mixing conventional glass ionomer cement?

    <p>Mechanical mixing with an amalgamator</p> Signup and view all the answers

    In terms of bonding mechanisms, what is the key interaction between the calcium ions and polyacrylic acid in glass ionomer cement?

    <p>Calcium ions react with the carboxylic groups forming cross-linked salts</p> Signup and view all the answers

    Which of the following statements is true regarding the restoration of primary teeth using glass ionomer cement?

    <p>It releases fluoride, offering additional benefits for primary teeth</p> Signup and view all the answers

    Which type of glass ionomer cement is specifically designed to resist moisture during initial setting?

    <p>Resin modified glass ionomer</p> Signup and view all the answers

    What role does water play in the setting of glass ionomer cement?

    <p>It hydrates the formed matrix and facilitates the formation of a stable gel.</p> Signup and view all the answers

    What can happen if glass ionomer cement is subjected to moisture contamination before setting?

    <p>The matrix may dissolve, weakening the material.</p> Signup and view all the answers

    What protective measure is necessary for glass ionomer cement during the setting process?

    <p>A layer of varnish must be used to shield it from environmental factors.</p> Signup and view all the answers

    What is the consequence of drying glass ionomer cement before it sets?

    <p>It can stop the reaction leading to surface cracking and reduced strength.</p> Signup and view all the answers

    What happens to the cross-linked matrix of glass ionomer cement during the setting phase?

    <p>It hydrates to form a stable gel, increasing strength.</p> Signup and view all the answers

    What is a key factor affecting the setting time of zinc phosphate cement?

    <p>Rate of addition of the liquid to powder</p> Signup and view all the answers

    Which property of polycarboxylate cement distinguishes it as a water-based cement?

    <p>Composition of polyacrylic acid in the liquid</p> Signup and view all the answers

    How does the pH level of freshly mixed zinc phosphate cement impact its clinical usage?

    <p>It requires the use of a cavity liner to protect the pulp</p> Signup and view all the answers

    Which factor leads to the fastest reaction and setting of zinc phosphate cement?

    <p>Fine particle size of the powder used</p> Signup and view all the answers

    What distinguishes copper and silver modified zinc phosphate cements from standard zinc phosphate cements?

    <p>Presence of bactericidal properties</p> Signup and view all the answers

    What is the optimal working time for mixing zinc phosphate cement?

    <p>1-1.5 minutes</p> Signup and view all the answers

    Which practice is crucial when mixing powder with liquid to prevent inconsistencies in the cement?

    <p>Incorporate powder slowly and in increments</p> Signup and view all the answers

    What characteristic is unique to the mechanical retention provided by zinc phosphate cement?

    <p>Mechanical interlocking with surface irregularities</p> Signup and view all the answers

    What is the key chemical interaction involved in bonding polycarboxylate cement to tooth structure?

    <p>Ionic interaction with calcium ions</p> Signup and view all the answers

    Which of the following best describes the setting reaction of zinc polycarboxylate cement?

    <p>An ionic reaction forming zinc polycaboxylate</p> Signup and view all the answers

    What is the recommended time frame for mixing polycarboxylate cement to achieve the best results?

    <p>30 to 40 seconds</p> Signup and view all the answers

    Which property of polycarboxylate cement specifically allows for effective manipulation despite its inherent challenges?

    <p>Lack of irritant potential compared to zinc phosphate</p> Signup and view all the answers

    Which of the following statements accurately reflects the biological properties of polycarboxylate cement?

    <p>It demonstrates greater biological acceptability due to lower acidity.</p> Signup and view all the answers

    In which clinical application is polycarboxylate cement most commonly utilized?

    <p>Permanent cementation of metallic restorations</p> Signup and view all the answers

    What characteristic differentiates the strength of zinc polycarboxylate cement from other cements?

    <p>It combines properties of both zinc phosphate and ZOE cement.</p> Signup and view all the answers

    What is a notable disadvantage of polycarboxylate cement compared to zinc phosphate cement?

    <p>Higher viscosity complicates mixing procedures.</p> Signup and view all the answers

    What is the primary composition of zinc phosphate cement powder?

    <p>Zinc oxide, magnesium oxide, and other oxides</p> Signup and view all the answers

    What is the result of the setting reaction between zinc oxide and phosphoric acid in zinc phosphate cement?

    <p>Formation of zinc phosphate and exothermic heat production</p> Signup and view all the answers

    How does the manipulation of zinc phosphate cement influence its properties?

    <p>Adding powder gradually helps prolong working time</p> Signup and view all the answers

    Which of the following statements accurately reflects the properties of zinc phosphate cement?

    <p>It can be affected by moisture prior to setting</p> Signup and view all the answers

    What is the primary use of Type I zinc phosphate cement?

    <p>For permanent cementation of alloy restorations</p> Signup and view all the answers

    During the setting process of zinc phosphate cement, which factor significantly influences the ionization of the acid?

    <p>The ratio of powder to liquid</p> Signup and view all the answers

    What occurs when additional water is introduced to the zinc phosphate cement mix?

    <p>It accelerates the rate of ionization and speeds up the setting time</p> Signup and view all the answers

    What manipulation technique is important to minimize heat release during mixing of zinc phosphate cement?

    <p>Incorporating powder gradually into the liquid</p> Signup and view all the answers

    Study Notes

    Uses of Dental Cements

    • Luting or cementation of restorations: holds indirect restorations in place like inlays, crowns, and bridges
      • Permanent cementation: long-term cementation
      • Temporary cementation: temporary restorations until permanent restorations are made
    • Filling material: temporary restoration when the final filling material can’t be finished in a single visit
    • Protection of the dental pulp: varnishes, liners, and bases
    • Cementation of orthodontic appliances
    • Gingival and periodontal packs
    • Endodontic sealers (root canal sealers)

    Requirements of Dental Cements

    • Biocompatible: non-toxic and non-irritating
    • Chemical or mechanical retention of restoration to tooth structure
    • High tensile strength, fracture toughness, and fatigue strength to resist fracture
    • Low solubility in neutral and acid environments to maintain marginal seal
    • Radiopaque: to be able to distinguish between a luting agent and caries under a prosthesis
    • Film thickness: needs to have low viscosity to fill the space between the restoration and tooth and ensure proper seating with a film thickness of 25 µm or less
    • Aesthetics: optical properties should be similar to tooth structure if used to cement translucent restorations
    • Has antibacterial effect

    Pulp Protection

    • Dental cements protect the pulp from:
      • Thermal injury
      • Chemical irritation
      • Galvanic shock
      • Mechanical forces during amalgam placement and chewing

    Cavity Liners

    • Thin layers of material (< 0.5 mm)
    • Act as a chemical barrier between the restoration and remaining dentin after cavity preparation

    Cavity Bases

    • Thicker layers (1-2 mm)
    • Used beneath restorations to protect the pulp from thermal, electrical, and mechanical injury

    Cavity Varnish

    • A protective barrier between dentin and restorative materials
    • Minimizes penetration of oral fluids at the restoration-tooth interface
    • Composed of resins in a volatile solvent which when applied to a cavity surface, evaporates leaving a thin film

    Pulp Capping

    • Placing a special material in contact with the pulp to encourage new dentin formation and promote healing
    • Two types:
      • Direct pulp capping: material placed directly over the pulp
      • Indirect pulp capping: material places indirectly over the pulp, but can still induce new dentin formation

    Types of Dental Cements

    • Cements based on Zinc Oxide
    • Cements based on Alumino Silicate Glasses
    • Other cements: Resin cements, Calcium-Hydroxide cements, Cavity liners and Varnishes

    Cements Based on Zinc Oxide

    • Zinc Oxide powder mixed with:
      • Eugenol: forms Zinc oxide eugenol cement
      • Phosphoric acid: forms Zinc Phosphate cement
      • Polyacrylic acid: forms Zinc Polycarboxylate cement

    Cements based on Alumino-Silicate Glass

    • Alumino-silicate glass powder mixed with:
      • Polyacrylic acid: forms Glass ionomer cement
      • Phosphoric acid: forms Silicate cement

    Zinc Oxide Eugenol Cement

    • Has a sedative effect on the pulp due to the presence of eugenol and its neutral pH
    • Two types:
      • Conventional zinc oxide eugenol
      • Modified zinc oxide eugenol
    • Forms: Powder and liquid

    Conventional Zinc Oxide Eugenol Cement

    • Powder Composition:
      • Zinc oxide (ZnO): main reactant
      • Rosin: reduces brittleness of set cement
      • Zinc stearate: plasticizer
      • Zinc acetate: accelerator and improves strength of the cement
    • Liquid Composition:
      • Eugenol (85%): active ingredient of clove oil
      • Olive oil (15%): makes cement more plastic during mixing and decreases brittleness after setting
    • Setting reaction:
      • Acid-base reaction which begins with hydrolysis of ZnO in the presence of water to form Zn(OH)2
      • Zn(OH)2 reacts with eugenol to form Zn eugenolate in a chelation reaction
      • Water is essential for the reaction, so it's faster in humid environments
      • The microstructure of the cement is formed of unreacted ZnO powder particles and eugenol embedded in a matrix of Zn eugenolate
    • Manipulation:
      • Powder/Liquid ratio is 3:1
      • Mix using a glass slab and stainless steel spatula
      • Most of the powder is added to the liquid at once, followed by smaller increments to adjust viscosity.
    • Properties:
      • pH is about 7, has little or no effect on pulp in deep cavities
      • Has a palliative obtudent effect on the pulp due to the presence of eugenol
      • Has a bacteriostatic effect due to the presence of eugenol
      • High solubility in which leached eugenol is replaced by water
      • Poor mechanical properties (compressive strength = 15 MPa, tensile strength = 5 MPa)
      • Opaque due to the presence of unreacted zinc oxide particles
      • Bond to enamel and dentin by mechanical interlocking
      • Eugenol inhibits the setting of resins, so can not be used with resin composite restorative materials
    • Uses:
      • Cavity liner in deep cavities
      • Temporary filling material
      • Temporary cementing agent
      • Surgical dressing
      • Root canal sealer

    Modifications of Zinc Oxide Eugenol Cement

    • Polymer reinforced cements: resin polymer is added to increase strength of the set cement
      • Composition:
        • Powder: Zinc oxide (80%), Polymethyl methacrylate (20%)

    Glass Ionomer Cements

    • Glass ionomer cements are used as luting agents for crowns and bridges, restorations in non-stress bearing areas, restorations in primary teeth, bases, and endodontic sealers.
    • Conventional glass ionomer cements (GICs) are available in powder and liquid, anhydrous cements, and capsules.
    • The powder of GICs contains calcium fluoro alumino silicate glass which consists of calcium fluoride (CaF2), sodium fluoride (NaF), silica (SiO2), and alumina (Al2O3).
    • The liquid of GICs is an aqueous solution of polyacrylic acid, itaconic acid, and tartaric acid.
    • The setting reaction of GICs is an acid-base reaction where the acid in the liquid attacks and dissolves the surface of glass particles, releasing calcium, aluminum, and fluoride ions.
    • Sodium ions form silica gel on the surface of the powder particles.
    • Calcium ions react with the carboxylic groups of the acid, forming a cross-linked carboxylic acid salt, leading to initial setting.
    • Aluminum ions react with the carboxylic groups of the acid, forming a stronger cross-linked cement than calcium because aluminum is trivalent and reacts with three carboxylic groups, while calcium is divalent and reacts with two.
    • Aluminum ions migrate slower than calcium ions, making the reaction of aluminum ions take longer than calcium.

    Types of GICs

    • Metal reinforced GICs:
      • Silver alloy admix: Made by incorporating amalgam alloy powder with the glass powder.
      • Cermet glass ionomer: Made by sintering or fusing silver particles to the glass ionomer powder.
    • Resin modified GICs:
      • Contain methacrylate resins similar to those used in composite resin materials.
      • Setting reactions include the conventional acid-base reaction and free radical polymerization reaction of the resin component.
    • Nanoionomer cements:
      • Combine resin-modified glass ionomer cement with nanofiller technology.
      • Fillers include:
        • Fluoroaluminosilicate glass of size less than 3 microns (average 1 micron)
        • Nanofillers (5–25 nm)
        • Nanocluster fillers (1.0–1.6 microns) derived from silica and zirconia.

    Resin Cements

    • Conventional composite resin cements:
      • Self-cured resin cements: Available as a two-component system to be mixed together, containing a powder and liquid or two paste system.
      • Light-cured resin cements: Available as a single paste that needs no mixing.
      • Dual-cured resin cements: Polymerize by both light and chemical curing simultaneously. Supplied as base and catalyst to be mixed before use.
    • Adhesive resin cements: Self-cured resin cements that contain an adhesive promoter such as 4-methacryloxy ethyl trimellitic anhydride (4-META).

    Advantages of Glass Ionomer Materials

    • Chemical bonding to tooth structures
    • Long-term fluoride release
    • Biocompatible
    • Good compressive strength
    • Low solubility in oral fluids

    Disadvantages of Glass Ionomer Materials

    • Technique sensitive to water contamination or dehydration
    • Low abrasion resistance
    • Short working time and long setting time
    • Brittleness (low tensile strength) and low fracture toughness

    Modifications of Glass Ionomer Cements

    • Modifications aimed to improve mechanical properties, sensitivity to dehydration, abrasion resistance, and optical properties.
    • Metal reinforced GICs: Increase abrasion resistance, little increase in compressive strength, and reduction in solubility. Also reduce fluoride release, bond strength with tooth structures, and aesthetics. Used for core build-up materials and posterior fillings in deciduous teeth.
    • Resin modified GICs: Hybrid materials that combine glass ionomer and composite resin. Improve mechanical properties, handleability, and esthetics while maintaining fluoride release.

    Role of Water in Glass Ionomer Cement

    • Water acts as the medium for the chemical reaction that forms the glass ionomer cement.
    • During setting, water hydrates the cross-linked matrix, creating a stable gel.
    • This gel strengthens the final material.
    • Dryness before setting stops the reaction and causes surface cracking, weakening the cement.
    • Moisture contamination before setting can dissolve the matrix, also reducing strength.
    • To ensure proper setting and strength, a varnish layer should protect the cement during the setting process.

    Zinc Phosphate Cement

    • Water based cement, packaged as a powder and liquid system
    • Powder: Zinc oxide (90%), magnesium oxide, other oxides
    • Liquid: Aqueous solution of phosphoric acid (30-40% H2O), Zinc or aluminum phosphate
    • Water controls ionization of the acid and influences the rate of reaction
    • Additional water increases the rate of ionization, which accelerates the reaction (shortens working and setting time)
    • Types: Type 1 for luting alloys restorations, Type II for bases
    • Setting reaction: The surface of the zinc oxide particles reacts with phosphoric acid to give an insoluble phosphate, resulting in a heterogeneous final set mass with shrinkages
    • Setting reaction is exothermic (produces heat): Zinc oxide + Phosphoric acid = Zinc phosphate + Heat
    • Mixing: Carried out on a cool thick glass slab using a cement spatula to dissipate the heat of reaction. Small increments of powder are added to the liquid to prolong the working time.
    • A small portion of the powder is added first to the whole liquid to neutralize the acidity and minimize heat liberation.
    • Large amounts of powder can be incorporated to saturate the mix.

    Polycarboxylate Cement

    • Water based cement
    • Composition:
      • Powder: Zinc oxide with some fluoride
      • Liquid: Polyacrylic acid (PAA) copolymer in water and tartaric acid to reduce viscosity
    • Bonds with tooth structure through ionic interaction between negatively charged molecules in the cement with positively charged atoms (such as calcium) in the tooth structure.
    • Carboxylic group in PAA reacts with Ca ion in tooth structures, forming an ionic bond between PAA and Ca ions in hydroxyapatite. This bond is stronger with enamel than dentin
    • Setting reaction (gelation): Zinc oxide + polyacrylic acid = zinc polycaboxylate
    • Manipulation: Powder is rapidly incorporated in the liquid in large quantities, mixing is done rapidly in 30 to 40 seconds
    • Mix should be used while it is still glossy. Working time is 2.5 to 3.5 minutes.
    • Properties:
      • Combines the strength properties of phosphate cement with the biologic acceptability of ZOE cement
      • Weaker than zinc phosphate and stronger than ZOE
      • Although polycarboxylate cement is acidic, it is not irritant as zinc phosphate cement due to the weaker nature of ployacrylic acid and lack of mobility of the polyacid chains
      • Higher solubility than zinc phosphate cement, silicophosphate and glass ionomer
      • Low irritation
      • Easy manipulation
      • Comparable film thickness with zinc phosphate
      • More difficult to mix than other cements because of its high viscosity

    Copper and Silver Modified Zinc Phosphate Cements

    • Similar to phosphate cements except that the powder contains copper or silver
    • Considered bactericidal
    • Used mainly for cementation of orthodontic appliances

    Classification of Dental Cements

    • Classified by the nature of the cement powder into:
      • Zinc oxide: ZOE, Zinc Phosphate, Zinc polycarboxylate cements.
      • Ion leachable glasses (alumino-silicate glass): Silicate and glass ionomer cements.

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    Description

    Explore the essential uses and requirements of dental cements in this informative quiz. From luting restorations to protecting dental pulp, understand the crucial role these materials play in dentistry. Test your knowledge on their properties and applications.

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