EFDA Dental Materials & Equipment Maintenance 5

Question 1

Which property of dental amalgam is described as the tendency to expand or contract under stress without fracturing?

Accepted Answer

Creep

Answer

Creep is the slow plastic deformation of amalgam under sustained compressive load, which can lead to marginal breakdown and ditching over time.

Question 2

Why must etchant (phosphoric acid) be completely rinsed from enamel before applying bonding agent?

Accepted Answer

Residual acid continues to demineralize enamel and disrupts bonding chemistry

Answer

Residual phosphoric acid must be thoroughly rinsed because it can continue etching and prevent proper resin infiltration into the enamel tubules.

Question 3

Which type of gypsum product is used to pour final working casts requiring high strength and hardness?

Accepted Answer

Type IV die stone

Answer

Type IV die stone (improved high-strength stone) has the highest compressive strength and lowest expansion, making it ideal for working casts and dies.

Question 4

What is the purpose of applying cavity varnish before placing zinc phosphate cement?

Accepted Answer

Seal dentinal tubules to reduce pulpal irritation from cement acidity

Answer

Cavity varnish seals dentinal tubules to protect the pulp from the low pH of freshly mixed zinc phosphate cement.

Question 5

When is biological monitoring (spore testing) of an autoclave required at minimum?

Accepted Answer

Weekly

Answer

The CDC and OSAP recommend weekly spore testing of sterilizers to verify that sterilization conditions are being achieved.

(EFDA) Expanded Function Dental Auxiliary Practice Test

(EFDA) Expanded Function Dental Auxiliary Practice Test

EFDA Dental Materials & Equipment Maintenance 5