Free EFDA Dental Materials & Chairside Assisting Skills Questions and Answers — Questions and Answers

Question 1: Which dental material is commonly used for temporary fillings?

Amalgam.
Composite resin.
Zinc oxide-eugenol (ZOE). (Correct answer)
Porcelain.

Correct answer: Zinc oxide-eugenol (ZOE).

Zinc oxide-eugenol (ZOE) is a commonly used dental material for temporary fillings due to its sedative effect on the pulp and good sealing properties. It is easily placed and removed, making it ideal for short-term restorations or as a base under other restorative materials. Its palliative qualities help soothe an irritated pulp.

Question 2: What is the primary function of a dental liner in a cavity preparation?

To replace dentin.
To provide aesthetic shading.
To act as a protective barrier for the pulp. (Correct answer)
To strengthen enamel.

Correct answer: To act as a protective barrier for the pulp.

A dental liner is applied in a thin layer to the deepest portion of a cavity preparation, primarily to act as a protective barrier for the pulp. It helps to protect the pulp from chemical irritation from restorative materials, thermal changes, and bacterial invasion. This promotes pulp vitality and reduces postoperative sensitivity, contributing to the longevity of the restoration.

Question 3: Which instrument is used to carry and condense amalgam into a cavity preparation?

Explorer.
Amalgam carrier and condenser. (Correct answer)
Scaler.
Curette.

Correct answer: Amalgam carrier and condenser.

The amalgam carrier is specifically designed to pick up and transfer freshly mixed amalgam from the amalgam well to the cavity preparation. Once the amalgam is in the cavity, a condenser is then used to pack and condense the amalgam firmly into the preparation. This ensures proper adaptation, eliminates voids, and achieves optimal density for a strong, durable restoration.

Question 4: What is the purpose of etching a tooth surface before applying composite resin?

To whiten the tooth.
To remove decay.
To improve adhesion of the resin material. (Correct answer)
To sterilize the tooth.

Correct answer: To improve adhesion of the resin material.

Etching the tooth surface with an acid (typically phosphoric acid) before applying composite resin creates microscopic porosities and roughens the enamel and dentin. This process significantly increases the surface area and mechanical retention, allowing the composite resin to bond more effectively to the tooth structure. This ensures a strong, durable, and long-lasting restoration.

Question 5: Which dental cement is often used for permanent cementation of crowns and bridges?

Zinc phosphate.
Polycarboxylate.
Glass ionomer. (Correct answer)
Temporary cement.

Correct answer: Glass ionomer.

Glass ionomer cement is frequently used for the permanent cementation of crowns and bridges due to its excellent biocompatibility, fluoride-releasing properties, and good adhesion to tooth structure and various restorative materials. It provides a strong, durable bond and helps prevent recurrent decay, making it a preferred choice for long-term restorations in dentistry.

Question 6: What is the correct sequence for mixing alginate impression material?

Add water to powder, mix vigorously for 1 minute.
Add powder to water, mix for 45-60 seconds until creamy. (Correct answer)
Mix powder and water separately, then combine.
Use cold water to extend working time.

Correct answer: Add powder to water, mix for 45-60 seconds until creamy.

The correct sequence for mixing alginate involves adding the powder to the water, which helps prevent dry spots and ensures a smooth, homogenous consistency. Mixing for 45-60 seconds until creamy allows for proper hydration and initiation of the chemical reaction, creating an ideal material for capturing accurate impressions. This method reduces air bubbles and ensures the material sets correctly.

Question 7: Which material is used to take final impressions for crowns and bridges?

Alginate.
Plaster of Paris.
Polyvinyl siloxane (PVS). (Correct answer)
Zinc oxide paste.

Correct answer: Polyvinyl siloxane (PVS).

Polyvinyl siloxane (PVS) is the material of choice for final impressions for crowns and bridges due to its excellent dimensional stability, accuracy, and tear resistance. Unlike alginate, which is used for diagnostic models, PVS captures extremely fine details of the prepared tooth and surrounding tissues. This precision is crucial for ensuring a precise fit and longevity of the final restoration.

Question 8: What is the role of a dental dam in restorative procedures?

To whiten teeth during treatment.
To isolate the operative field from saliva and debris. (Correct answer)
To numb the gums.
To polish restorations.

Correct answer: To isolate the operative field from saliva and debris.

A dental dam is a thin, flexible sheet used to isolate one or more teeth from the rest of the oral cavity during restorative procedures. Its primary role is to create a dry, clean, and aseptic working environment by preventing contamination from saliva, blood, and debris. This isolation is critical for the success of many dental treatments, especially those involving bonding agents like composite restorations, as it ensures optimal adhesion and reduces the risk of infection.

Question 9: Which chairside skill is critical when assisting with a composite restoration?

Taking radiographs.
Controlling moisture with suction and air/water syringe. (Correct answer)
Mixing plaster.
Applying fluoride varnish.

Correct answer: Controlling moisture with suction and air/water syringe.

For composite restorations, maintaining a completely dry and clean operative field is paramount for successful bonding and longevity of the restoration. The dental assistant's critical chairside skill involves expertly using high-volume evacuation (suction) and the air/water syringe to control saliva, blood, and debris. This moisture control prevents contamination of the etched tooth surface and bonding agents, ensuring optimal adhesion and preventing premature failure of the composite.

Free EFDA Dental Materials & Chairside Assisting Skills Questions and Answers

Which dental material is commonly used for temporary fillings?