1)Dental Cements in Restorative Dentistry

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Questions and Answers

Which cement can be used for pulp capping under composite restorations?

  • Type III glass ionomer cement
  • Resin cement
  • Zinc polycarboxylate cement (correct)
  • Zinc phosphate cement

What is the primary purpose of using zinc phosphate cement?

  • Cavity liner
  • Pulp protection
  • Temporary luting (correct)
  • Root canal sealing

Which cement has been in use since 1878 and is considered one of the oldest cements?

  • Resin cement
  • Zinc polycarboxylate cement (correct)
  • Zinc oxide eugenol cement
  • Glass ionomer cement

For which restorative material can reinforced ZOE be used as a base?

<p>Amalgam restorations (A)</p> Signup and view all the answers

Which cement is suitable for indirect pulp capping during a dental procedure?

<p>Zinc polycarboxylate cement (D)</p> Signup and view all the answers

What is the main property of zinc phosphate cement specified in the text?

<p>Film thickness &lt; 25 microns (C)</p> Signup and view all the answers

What is the film thickness of Type II Zinc Phosphate cement?

<p>25-40 microns (D)</p> Signup and view all the answers

What is the setting reaction of Zinc Phosphate cement?

<p>Exothermic acid-base reaction (C)</p> Signup and view all the answers

What is the tensile strength of Type II Zinc Phosphate cement?

<p>5.5 Mpa (D)</p> Signup and view all the answers

How long does it take for Type II Zinc Phosphate cement to retain 75% of its ultimate strength?

<p>1 hour (A)</p> Signup and view all the answers

What is a disadvantage of Zinc Polycarboxylate Cement?

<p>Solubility in water (C)</p> Signup and view all the answers

How does Zinc Polycarboxylate Cement set?

<p>Acid-base reaction with calcium (C)</p> Signup and view all the answers

What is the setting reaction of zinc oxide eugenol cement?

<p>Zn(OH)2 + 2HE -&gt; ZnE2 + 2H2O (D)</p> Signup and view all the answers

What is one of the disadvantages of zinc oxide eugenol cement in terms of clinical use?

<p>Low compressive strength (B)</p> Signup and view all the answers

Which of the following statements is true about the biocompatibility of zinc oxide eugenol cement?

<p>Sedative effect on the pulp (B)</p> Signup and view all the answers

When is zinc oxide eugenol cement commonly used in clinical practice?

<p>Temporary restorations (A)</p> Signup and view all the answers

What is a notable advantage of zinc oxide eugenol cement over zinc phosphate cement?

<p>Better marginal seal (B)</p> Signup and view all the answers

Why is zinc oxide eugenol cement not recommended as a base material for unfilled and filled resins?

<p>It interferes with the polymerization process of resins (C)</p> Signup and view all the answers

What is the main component of the powder in the EBA cement?

<p>Zinc oxide (D)</p> Signup and view all the answers

What is the benefit of adding fused quartz, alumina and dicalcium phosphate to the EBA cement?

<p>Increases compressive and tensile strength (D)</p> Signup and view all the answers

What is the main component of the liquid in the EBA cement?

<p>Ortho-ethoxybenzoic acid (EBA) (C)</p> Signup and view all the answers

What is the main purpose of the polymer reinforced zinc oxide powder?

<p>Increases strength (C)</p> Signup and view all the answers

What is the main role of the acetic acid in the polymer reinforced zinc oxide cement?

<p>Accelerates the setting reaction (B)</p> Signup and view all the answers

What is the main disadvantage of the EBA cement?

<p>Plastic deformation (B)</p> Signup and view all the answers

What is the primary setting reaction of zinc polycarboxylate cement?

<p>Acid-base reaction (B)</p> Signup and view all the answers

Which factor increases the working time of zinc polycarboxylate cement?

<p>Decreasing the temperature (A)</p> Signup and view all the answers

What is the typical powder/liquid ratio recommended for mixing zinc polycarboxylate cement?

<p>1.5/1 (A)</p> Signup and view all the answers

Which of the following statements about the bond of zinc polycarboxylate cement to tooth structure is correct?

<p>It bonds through a chemical reaction with calcium in tooth structure (A)</p> Signup and view all the answers

Which property of zinc polycarboxylate cement is accurately described in the text?

<p>Low tensile strength (2.4-4.4 MPa) (B)</p> Signup and view all the answers

What is the initial pH of the liquid component of zinc polycarboxylate cement?

<p>1.7 (D)</p> Signup and view all the answers

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Study Notes

Properties of Dental Cements

  • Resistance to solubility in the oral cavity
  • Bonding
  • Compressive and tensile strength
  • Biocompatibility
  • Working time
  • Protects pulp from mechanical and electrical stimuli

Classification of Dental Cements

  • Permanent luting cements
  • Temporary luting cements
  • Permanent restorative materials
  • Temporary restorative materials
  • Bases: under amalgam/composite/gold
  • Pulp capping: indirect pulp capping/direct pulp capping
  • Cavity liners: under amalgam/composite

Zinc Phosphate Cement

  • First introduced in 1878 and still used today
  • Type I: used for cementation; film thickness < 25 microns
  • Type II: used as a base and for luting; film thickness 25-40 microns
  • Powder composition: 90.2% ZnO, 8.2% MgO, 1.4% SiO2, 0.1% Bi2O3, 0.1% BaO, Ba2SO4, CaO
  • Acid-base reaction rate
  • Setting reaction: zinc oxide + phosphoric acid
  • Manipulation: glass slab, dry, lower temperature for longer working time
  • Mechanical Properties:
    • Compressive strength: 104 Mpa
    • Tensile strength: 5.5 Mpa
    • Modulus of Elasticity: 13.7 gigapascals
    • Retention of cement is by mechanical interlocking
  • Biocompatibility: phosphoric acid, liquid pH 2.0, acidity, irritation
  • Clinical uses: base, temporary restoration, cementation
  • Advantages: long record of clinical acceptability, high compressive strength, thin film thickness
  • Disadvantages: low initial pH, lack of adhesion to tooth structure, lack of anticariogenic effect, soluble in water

Zinc Polycarboxylate Cement

  • Introduced in the 1960s
  • Chelation reaction
  • Sets by an acid-base reaction between powder and liquid
  • Clinical use: base, temporary restorations, cement crowns, stainless steel crown
  • Advantages: adhesion, rapid rise in pH upon cementation
  • Disadvantages: lack of penetration into dentinal tubules, short working time, not resistant to plastic deformation

Zinc Oxide Eugenol Cement

  • Introduced in the 1890s
  • Less soluble in oral fluids
  • Better marginal seal than zinc phosphate
  • Powder composition: 69% ZnO, 29.3% white rosin, 1% zinc stearate, 0.7% zinc acetate
  • Liquid composition: 85% Eugenol, 15% olive oil
  • Setting reaction: ZnO + H2O → Zn(OH)2
  • Manipulation: wet cotton pellet for smoothening, clean up, and hardening of the restoration
  • Biocompatibility: sedative effect, less irritant to the pulp, antibacterial, pH= 7
  • Clinical use: temporary cementation, temporary restoration, deep cavity preparation
  • Advantages: soothing effect on the pulp, good short-term sealing
  • Disadvantages: high solubility, low strength, low compressive strength, long setting time

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