EFDA - Expanded Function Dental Auxiliary Bases, Liners, and Sealants Questions and Answers — Questions and Answers
Question 1: Which of the following materials is applied in a thin layer to seal dentinal tubules and is contraindicated for use with composite resin restorations because it interferes with adhesion?
- Calcium Hydroxide
- Glass Ionomer
- Cavity Varnish (Correct answer)
- Zinc Phosphate Cement
Correct answer: Cavity Varnish
Cavity varnish, such as Copalite, is a liquid resin used to seal dentinal tubules to reduce microleakage. However, it is not compatible with resin composite materials because it inhibits the polymerization and bonding of the resin to the tooth structure.
Question 2: A patient requires a deep amalgam restoration on a molar. To provide thermal insulation for the pulp and to support the restoration during placement, the dentist will likely request which material to be placed in a thick layer?
- A dental liner
- A dental base (Correct answer)
- A cavity sealant
- A dentin sealer
Correct answer: A dental base
A dental base is placed in a thick layer on the floor of the cavity preparation. Its primary functions are to provide thermal insulation to protect the pulp from temperature changes and to be strong enough to support the occlusal forces absorbed by the final restoration.
Question 3: Which of the following is a primary function of a calcium hydroxide liner, such as Dycal?
- To release fluoride and prevent recurrent decay.
- To provide high compressive strength under a restoration.
- To chemically bond to the overlying restorative material.
- To stimulate the formation of reparative (secondary) dentin. (Correct answer)
Correct answer: To stimulate the formation of reparative (secondary) dentin.
Calcium hydroxide is well-known for its therapeutic property of stimulating odontoblasts to form reparative or secondary dentin, especially when placed over the deepest portion of a cavity preparation close to the pulp. Its high pH (around 11) acts as an irritant that promotes this defensive response from the pulp.
Question 4: An EFDA is preparing materials for a Class V restoration that will use a glass ionomer (GI) base. Which of the following is a key advantage of using a GI material in this scenario?
- It has a sedative effect on the pulp.
- It releases fluoride, which can help inhibit recurrent caries. (Correct answer)
- It is the strongest base material available.
- It requires a varnish to be placed over it for protection.
Correct answer: It releases fluoride, which can help inhibit recurrent caries.
A significant advantage of glass ionomer cements is their ability to release fluoride. This fluoride release can help remineralize the adjacent tooth structure and reduce the incidence of recurrent caries at the restoration margin.
Question 5: When mixing Zinc Phosphate cement to be used as a base, why is it crucial to mix it on a cool, glass slab over a wide area?
- To accelerate the setting time for a faster procedure.
- To increase the final compressive strength of the cement.
- To dissipate the heat from the exothermic reaction. (Correct answer)
- To incorporate more powder into the liquid for a thicker mix.
Correct answer: To dissipate the heat from the exothermic reaction.
The reaction between the zinc phosphate powder and the phosphoric acid liquid is exothermic, meaning it releases a significant amount of heat. Mixing on a cool glass slab helps to dissipate this heat, which slows the setting reaction, allows more powder to be incorporated, and increases the working time before placement.
Question 6: A dentist has completed a deep cavity preparation for an amalgam restoration and is concerned about postoperative sensitivity and microleakage. Which of the following materials would be applied in a thin layer to seal the dentinal tubules *before* placing the amalgam?
- Resin-modified glass ionomer
- Flowable composite
- Cavity Varnish (Correct answer)
- Calcium hydroxide
Correct answer: Cavity Varnish
A cavity varnish is specifically used under amalgam restorations to seal the dentinal tubules. This sealing action reduces microleakage and can help prevent postoperative sensitivity by blocking the influx of fluids and bacteria.
EFDA - Expanded Function Dental Auxiliary Bases, Liners, and Sealants Questions and Answers
Which of the following materials is applied in a thin layer to seal dentinal tubules and is contraindicated for use with composite resin restorations because it interferes with adhesion?