EFDA Bases, Liners, and Matrices 5

Question 1

Why is zinc oxide eugenol (ZOE) cement considered a 'sedative' base?

Accepted Answer

Eugenol has a palliative effect that reduces pulpal inflammation and sensitivity

Answer

Eugenol's analgesic and obtundent properties soothe irritated pulp tissue, making ZOE ideal for symptomatic or recently excavated teeth.

Question 2

When using a sectional matrix system, the ring retainer is placed:

Accepted Answer

Into the embrasures to separate teeth and stabilize the band

Answer

The separation ring is inserted into the buccal and lingual embrasures to press the matrix band tight against the proximal box.

Question 3

A liner differs from a base primarily in that a liner:

Accepted Answer

Is a thin layer applied mainly for biological protection rather than mechanical support

Answer

Liners are applied in thin layers (under 0.5 mm) to provide biological and chemical protection without the bulk or compressive strength of a base.

Question 4

What happens if the matrix band is not burnished (adapted) to the gingival margin before placing amalgam?

Accepted Answer

A ledge or flash of amalgam will form at the gingival margin

Answer

An unadapted band leaves a gap at the gingival margin where amalgam can flow, creating a ledge that predisposes to plaque accumulation.

Question 5

Which liner is appropriate for use directly under composite resin without inhibiting polymerization?

Accepted Answer

Light-cured calcium hydroxide or resin-modified glass ionomer

Answer

Light-cured calcium hydroxide and resin-modified glass ionomer liners are compatible with composite resin and will not inhibit its polymerization.

(EFDA) Expanded Function Dental Auxiliary Practice Test