Zinc Oxide-Eugenol Paste in Dentistry
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Zinc Oxide-Eugenol Paste in Dentistry

Learn about the composition and properties of Zinc Oxide-Eugenol pastes, a rigid impression material used in dentistry for making complete dentures. Explore how the paste hardens by a chemical reaction and its applications in denture preparation.

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Questions and Answers

What is the primary function of the inert oils in Zinc Oxide-Eugenol impression materials?

To act as a plasticizer and decrease the irritating action of eugenol

Which component is responsible for imparting thermoplastic properties to the set Zinc Oxide-Eugenol impression?

Gum rosin

What is the primary component of the base paste (Tube 1) in Zinc Oxide-Eugenol impression materials?

Zinc oxide

What is the purpose of the accelerator (MgCl2 or CaCl2) in Zinc Oxide-Eugenol impression materials?

<p>To hasten the setting reaction</p> Signup and view all the answers

What is the primary function of the filler (talc or kaolin) in Zinc Oxide-Eugenol impression materials?

<p>To give the paste a specific consistency</p> Signup and view all the answers

What is the main reason for using oil of cloves instead of pure eugenol in Zinc Oxide-Eugenol impression materials?

<p>Oil of cloves produces less of a burning sensation</p> Signup and view all the answers

What is the effect of a drop of water or alcohol on the setting time of a zinc oxide-eugenol impression material?

<p>It decreases the setting time.</p> Signup and view all the answers

Which of the following statements about the dimensional changes of a zinc oxide-eugenol impression material is correct?

<p>It undergoes a negligible shrinkage of less than 0.1% during hardening.</p> Signup and view all the answers

What is the relationship between the flow and setting time of a zinc oxide-eugenol impression material?

<p>The relationship between flow and setting time is complex and depends on the specific product.</p> Signup and view all the answers

Which of the following properties of a zinc oxide-eugenol impression material is mentioned in the text?

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

What is the recommended disinfection procedure for a zinc oxide-eugenol impression material?

<p>Immerse in 2% alkaline glutaraldehyde for the recommended time, then rinse.</p> Signup and view all the answers

What is the effect of increasing the mixing time within limits on the setting time of a zinc oxide-eugenol impression material?

<p>Increasing the mixing time decreases the setting time.</p> Signup and view all the answers

Which of the following is a component of zinc oxide-eugenol impression materials?

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

What is the primary role of eugenol in zinc oxide-eugenol impression materials?

<p>To initiate the setting reaction</p> Signup and view all the answers

Which of the following factors can affect the setting reaction of zinc oxide-eugenol impression materials?

<p>All of the above</p> Signup and view all the answers

What is the primary advantage of zinc oxide-eugenol impression materials?

<p>Low cost</p> Signup and view all the answers

Which of the following is a disadvantage of zinc oxide-eugenol impression materials?

<p>Unpleasant taste</p> Signup and view all the answers

What is the purpose of zinc oxide in zinc oxide-eugenol impression materials?

<p>To provide rigidity and strength</p> Signup and view all the answers

Study Notes

Introduction to Impression Materials

  • Dental impression is a negative replica of hard and soft tissues of the mouth, made with a material that sets while still in contact with the tooth and tissues.
  • A cast (model) is a positive replica of the oral hard or soft structures.

Purpose of Taking Impression

  • To study alignment of teeth
  • Construction of special (custom) tray
  • Treatment planning
  • Fabrication of indirect restorations

Types of Trays

  • Stock trays
  • Special tray

Desirable Properties of Impression Materials

  • Pleasant odor, taste, and acceptable color
  • Absence of toxic or irritant constituents
  • Adequate shelf life for requirements of storage and distribution
  • Not expensive
  • Easy to use with the minimum of equipment
  • Readily wets oral tissues
  • Setting characteristics that meet clinical requirements

Zinc Oxide Eugenol (ZOE) Impression Material

Composition

  • Tube 1 (Base): 80% Zinc oxide
  • Tube 2 (Accelerator): Oil of cloves or eugenol (15%), Inert oil, Gum rosin and oils (65%), Filler (talc or kaolin) (16%), Accelerator (MgCl2 or CaCl2) and water (4%)

Properties

  • Non-toxic, but eugenol can be irritant to patients
  • Negligible shrinkage (less than 0.1%) during hardening
  • Inelastic, cannot be used for recording undercuts
  • Adequate working time for border molding in the mouth
  • Adequate fine details and dimensionally stable

Manipulation

  • Equal length of each paste is dispensed on the mixing pad or glass slap
  • Mixed with a stiff stainless steel spatula for approximately 1 minute until a uniform color is achieved

Factors Affecting Setting Time

  • Temperature: increased temperature decreases setting time
  • Addition of water or alcohol: decreases setting time
  • Inert oils: increases setting time
  • Ratio of the two pastes: affects setting time depending on the product
  • Mixing time: increased mixing time within limits decreases setting time

Advantages

  • Adheres well to dried surfaces of compound, resin, and shellac bases
  • Sufficient resistance to build up borders if the tray is slightly deficient
  • Hard when set, can be taken in and out of the mouth repeatedly
  • Can be repaired

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