EFDA - Expanded Function Dental Auxiliary Bases, Liners, and Matrices Questions and Answers

Question 1

A dentist completes a deep cavity preparation on a molar with a suspected microscopic pulp exposure. Which material is specifically placed in a thin layer over the site to promote the formation of reparative dentin?

Accepted Answer

Calcium Hydroxide

Answer

Calcium hydroxide is well-known for its high alkalinity (high pH) which provides an antibacterial effect and stimulates odontoblasts to form a dentin bridge, also known as reparative or tertiary dentin, over a pulp exposure.

Question 2

An EFDA is preparing materials for a large Class II composite restoration. The dentist requests a base for thermal insulation. Which of the following materials must be AVOIDED for use as a base directly under a composite resin restoration?

Accepted Answer

Zinc Oxide-Eugenol (ZOE)

Answer

The eugenol component in ZOE is known to inhibit the polymerization (setting reaction) of resin-based materials like composite. This interference compromises the bond and the overall integrity of the final restoration.

Question 3

For a Class II MO composite restoration on tooth #29, which matrix system is generally preferred to achieve the most anatomically correct contact and contour?

Accepted Answer

Sectional matrix with a separating ring

Answer

Sectional matrix systems are designed to recreate the tight, convex contacts and natural contours of posterior teeth more effectively than a universal Tofflemire band, which tends to flatten the proximal surface. The separating ring provides the necessary tooth separation to ensure a firm contact after the matrix is removed.

Question 4

When placing a posterior matrix band for a Class II restoration, what is the primary function of a wooden or plastic wedge?

Accepted Answer

To adapt the band tightly against the gingival margin of the preparation.

Answer

The wedge is placed firmly in the gingival embrasure to seal the gingival margin of the matrix band against the tooth. This critical step prevents an overhang of restorative material and helps create a proper gingival contour. It also provides slight separation of the teeth to compensate for the band's thickness.

Question 5

Which of the following statements best describes the primary difference between a dental liner and a dental base?

Accepted Answer

Liners are placed in a thin layer for pulpal protection, while bases are placed in a thicker layer for mechanical support.

Answer

The main distinction lies in their thickness and primary function. Liners are thin coatings (typically <0.5mm) designed to seal dentinal tubules and protect the pulp chemically or therapeutically. Bases are thicker layers that provide thermal insulation and, importantly, distribute occlusal forces, acting as a supportive foundation for the final restoration.

(EFDA) Expanded Function Dental Auxiliary Practice Test

(EFDA) Expanded Function Dental Auxiliary Practice Test

EFDA - Expanded Function Dental Auxiliary Bases, Liners, and Matrices Questions and Answers