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Viva question and answers in Dental cements


  1. GIC cements are composed of

Aluminosilicate powder and polyacrylate

  1. Glass Powder: Typically makes up around 60-70% of the GIC. It consists of finely ground glass particles, such as silicate glass, and can contain various elements like aluminum, boron, and others to enhance properties.
  2. Polymeric Acid (Liquid): Comprises about 20-30% of the GIC. This is often polyacrylic acid or a similar polymeric acid.
  3. Water: Makes up about 10-20% of the GIC. It is used as a mixing liquid and to initiate the setting reaction.
  4. Setting Accelerators: These are added in small quantities and may vary, but they usually make up less than 5% of the GIC. Common setting accelerators include tartaric acid or maleic acid.
  5. Fluoride: Some GIC formulations may contain fluoride, typically in low percentages, around 0.1% or less.

Please note that these percentages are approximate and can vary from one GIC brand or type to another. Manufacturers may have proprietary formulations that can impact the exact composition of their products. Additionally, there are different types of GICs for various dental applications, each with its unique properties and composition.

For precise information on the composition of a specific GIC product, it is best to refer to the manufacturer’s product documentation or contact them directly.

  1. Which cement accelerates the formation of reparative dentin?

Calcium hydroxide, because of its high pHvalue, acts as a pulp irritant and stimulates reparative dentin formation

  1. What is the minimum thickness for type1 zinc phosphate cement?

25 microns or less. It is the oldest luting cement called as universal luting cements.

  1. Composition of zinc phosphate cement?

Zinc Oxide (Powder): Typically makes up around 80-90% of the cement. This component is responsible for the strength and hardness of the cement.

Magnesium Oxide: Often added in smaller quantities, typically around 5-10%. Magnesium oxide helps control the setting time of the cement.

Phosphoric Acid (Liquid): Comprises about 10-20% of the cement. This liquid is responsible for the cement’s adhesive properties and setting reaction.

Aluminium phosphate, water and zinc phosphate

  1. What is the setting time of zinc phosphate cement?

Initial Setting Time: The initial setting time, also known as the working time, is typically around 3 to 5 minutes. This is the time during which the mixed cement can be manipulated and placed in the dental restoration.

Final Setting Time: The final setting time, when the cement has completely hardened and achieved its maximum strength, usually occurs within 7 to 9 minutes after mixing.

  1. What is the pH of fully set zinc phosphate?

6 to 7

pH of the mix after mixing is approximately 2, but increases rapidly to a pH of 6 in 24 to 48 hours. So damage to pulp from acid occurs during the first few hours after insertion

  1. What is the thickness of type2 zinc phosphate cement?

40 microns, medium grained for luting and filling.

  1. What is the ph of zinc oxide eugenol cement at the time of insertion?

Ph is 7 and it is one of the least irritating of all dental cements and provides excellent seal against leakage

  1. What is the composition of ZOE cement?

Zinc Oxide (Powder): Typically makes up around 70-80% of the cement. Zinc oxide provides the cement’s structural and mechanical properties.

Eugenol (Liquid): Comprises about 10-30% of the cement. Eugenol is an essential component that gives ZOE cement its therapeutic and soothing properties for dental pulp.

10.Which component of zinc oxide eugenol cement gives its strength?

Zinc oxide

viva question and answers related to zinc polycarboxylate cement

Here are 50 viva questions and answers related to dental cements:

  1. What are dental cements, and why are they used in dentistry?

Answer: Dental cements are materials used in dentistry to bond, seal, or fill teeth. They are essential for various dental procedures to restore, protect, or enhance the function and aesthetics of teeth.

  1. Can you name some common types of dental cements and briefly describe their uses?

Answer: Common types include zinc phosphate, glass ionomer, resin-based, zinc oxide eugenol, and zinc oxide non-eugenol cements. They are used for tasks like cementing crowns and bridges, filling cavities, and providing temporary solutions.

  1. How does the composition of zinc phosphate cement differ from glass ionomer cement?

Answer: Zinc phosphate cement typically consists of zinc oxide powder and phosphoric acid liquid, while glass ionomer cement contains glass powder and polymeric acid.

  1. Explain the setting reaction in zinc phosphate cement and name its components.

Answer: The setting reaction involves an acid-base reaction between the phosphoric acid and zinc oxide. Water is used to initiate the setting.

  1. What are the primary components of glass ionomer cement, and what are their roles?

Answer: Glass ionomer cement comprises glass powder for strength and polymeric acid for adhesion and setting.

  1. How does resin-modified glass ionomer cement (RMGIC) differ from traditional glass ionomer cement?

Answer: RMGIC incorporates resin, enhancing its mechanical properties and adhesion.

  1. What is the primary difference between luting and restorative dental cements?

Answer: Luting cements are used for cementing crowns and bridges, while restorative cements are used for filling cavities and other tooth restorations.

**8. How does the working time of dental cement affect clinical use?

Answer: The working time determines how long the cement can be manipulated and placed. It’s crucial for proper placement.

**9. What factors can influence the setting time of dental cements?

Answer: Factors include temperature, humidity, and the specific cement type used.

**10. How does temperature affect the setting time of dental cements?

Answer: Higher temperatures generally shorten the setting time, while lower temperatures can prolong it.

**11. What are the advantages and disadvantages of zinc oxide eugenol (ZOE) cement?

Answer: ZOE has excellent soothing properties but limited strength and adhesion.

**12. In what dental procedures is ZOE cement commonly used?

Answer: ZOE cement is often used for temporary fillings and as a sedative dressing.

**13. Describe the composition and uses of zinc polycarboxylate cement.

Answer: Zinc polycarboxylate cement comprises zinc oxide and a polymeric acid. It is used for cementing crowns and bridges.

**14. What are the properties of zinc polycarboxylate cement that make it suitable for certain clinical indications?

Answer: It offers good adhesion, biocompatibility, and a relatively long working time.

**15. Explain the composition and properties of resin-based cements in dental applications.

Answer: Resin-based cements are composed of resin and other additives. They offer excellent adhesion, strength, and esthetics.

**16. How does the setting mechanism of resin-based cement differ from traditional dental cements?

Answer: Resin-based cements set through a polymerization reaction, while traditional cements set through acid-base reactions.

**17. Describe the ideal properties of a luting cement used for cementing crowns and bridges.

Answer: Ideal properties include good adhesion, ease of use, and a suitable setting time.

**18. What are the different types of temporary cements, and how do they differ from permanent cements?

Answer: Temporary cements are used for provisional restorations, are less adhesive, and have a shorter lifespan than permanent cements.

**19. How is adhesion achieved in resin-based cement applications?

Answer: Adhesion is achieved through the use of bonding agents and the interaction of resin with the tooth structure.

**20. What is the role of bonding agents in enhancing the adhesion of resin-based cements?

Answer: Bonding agents are used to prepare the tooth surface and promote the adhesion of resin materials.

**21. Explain the composition and uses of zinc oxide non-eugenol (ZONe) temporary cements.

Answer: ZONe cements contain zinc oxide and other additives. They are used for provisional restorations.

**22. Under what circumstances might you choose a temporary cement over a permanent one for a dental restoration?

Answer: Temporary cements are used when the restoration is meant to be provisional or when a permanent cement is not readily available.

**23. Discuss the composition and clinical uses of glass ionomer-based luting cements.

Answer: Glass ionomer luting cements contain glass powder and polymeric acid. They are used for cementing crowns, bridges, and orthodontic bands.

**24. How does the release of fluoride from glass ionomer cements benefit dental health?

Answer: Fluoride release helps prevent tooth decay and offers a protective effect on the adjacent tooth structure.

**25. Explain the mechanism of adhesion in glass ionomer cements.

Answer: Adhesion in glass ionomer cements is achieved through the formation of ionic bonds between the cement and the tooth structure.

**26. What are the advantages and disadvantages of using resin-modified glass ionomer cements?

Answer: RMGIC combines the properties of glass ionomer and resin-based cements, offering good adhesion and strength but with some limitations.

**27. Describe the role of luting agents in the retention of dental crowns and bridges.

Answer: Luting agents provide the necessary adhesive strength to retain crowns and bridges on prepared tooth structures.

**28. How does the thermal expansion of dental cements affect their clinical performance?

Answer: Dental cements should have similar thermal expansion characteristics to the tooth structure to minimize the risk of micro-leakage and restoration failure.

**29. What factors should be considered when selecting a dental cement for a specific clinical case?

Answer: Factors to consider include the type of restoration, the condition of the tooth, the desired retention, and the material properties of the cement.

**30. Discuss the properties and clinical indications for using resin cements in indirect restorations.

Answer: Resin cements are suitable for cementing ceramics, crowns, and veneers due to their adhesive properties and esthetics.

**31. Explain the composition and characteristics of zinc oxide non-eugenol (ZONe) temporary cements.

Answer: ZONe cements are composed of zinc oxide and additives. They offer soothing properties and are used for provisional restorations.

**32. How can you enhance the adhesion of glass ionomer cements to tooth structure?

Answer: Good isolation, proper conditioning of the tooth surface, and the use of polyacrylic acid (conditioner) can enhance adhesion.

**33. Describe the handling properties and setting mechanism of zinc phosphate cement.

Answer: Zinc phosphate cement has a relatively short working time and sets through an acid-base reaction.

**34. What is the role of varnishes in enhancing the performance of dental cements?

Answer: Varnishes are used to seal dentin tubules and reduce post-operative sensitivity when using eugenol-containing cements.

**35. How do you remove excess cement after cementing a restoration, and why is it important?

Answer: Excess cement should be removed carefully with dental instruments to avoid interference with the occlusion and prevent gingival irritation.

**36. What precautions should be taken when handling and mixing dental cement materials?

Answer: Precautions include wearing appropriate personal protective equipment, following manufacturer instructions, and ensuring proper moisture control.

**37. How do you determine the thickness of a cement film when cementing a restoration?

Answer: The ideal thickness is typically specified by the manufacturer, and the cement should be applied accordingly.

**38. What are the potential causes of incomplete or improper cement mixing?

Answer: Incomplete or improper mixing can occur due to incorrect powder-to-liquid ratio, inadequate mixing time, or inadequate trituration.

**39. Explain how moisture control is critical when using dental cements.

Answer: Moisture control is crucial to prevent contamination and ensure proper adhesion.

**40. How can you address post-operative sensitivity related to dental cement use?

Answer: Ensuring complete removal of excess cement and using varnishes or liners can help reduce post-operative sensitivity.

**41. Describe the ideal storage conditions for dental cement materials to ensure their longevity.

Answer: Dental cements should be stored in a cool, dry place and protected from moisture and contaminants.

**42. What precautions should be taken when handling eugenol-containing dental cements?

Answer: Precautions include avoiding contact with the skin and eyes, using appropriate personal protective equipment, and working in a well-ventilated area.

**43. Explain the concept of solubility and how it applies to dental cements.

Answer: Solubility refers to the ability of a material to dissolve in a liquid. Dental cements should have low solubility to maintain their integrity.

**44. What is the effect of the powder-to-liquid ratio on the properties of dental cements?

Answer: The powder-to-liquid ratio affects the consistency, working time, and strength of the cement.

**45. How can you adjust the consistency of a dental cement mix during preparation?

Answer: The consistency can be adjusted by adding more powder or liquid to achieve the desired mix.

**46. What is the clinical significance of the radiopacity of dental cements?

Answer: Radiopacity is important for diagnosing issues like cement remnants on radiographs and ensuring proper placement of restorations.

**47. Discuss the role of cementation in the retention and longevity of dental restorations.

Answer: Proper cementation is critical to retain dental restorations and prevent their premature failure.

**48. How can you assess the quality and integrity of a cemented dental restoration?

Answer: Assessment includes checking the occlusion, evaluating the margins, and ensuring there is no excess cement.

**49. What are the potential complications and failures associated with the use of dental cements, and how can they be managed or prevented?

Answer: Complications can include post-operative sensitivity, micro-leakage, and restoration failure. Proper technique and material selection can help prevent these issues.

These questions and answers provide a comprehensive overview of dental cements and can serve as a helpful resource for students and professionals in the field of dentistry.