ADEX Dental Biomaterials 3

Question 1

In amalgam, the gamma-2 phase (Sn8Hg) is considered undesirable because it:

Accepted Answer

Is the weakest and most corrosion-prone phase

Answer

The gamma-2 phase is the weakest component of amalgam and is highly susceptible to corrosion, leading to marginal breakdown.

Question 2

Which initiator-accelerator system is used in chemically activated (self-cured) composite resins?

Accepted Answer

Benzoyl peroxide and tertiary amine

Answer

Self-cured composites use a two-paste system where benzoyl peroxide in one paste reacts with a tertiary amine in the other to initiate polymerization.

Question 3

The purpose of adding silane coupling agent to composite resin filler particles is to:

Accepted Answer

Bond the inorganic filler to the organic resin matrix

Answer

Silane coupling agents form a chemical bridge between the inorganic glass filler and the organic resin matrix, enhancing composite strength and durability.

Question 4

What is galvanic corrosion in the oral cavity?

Accepted Answer

Electrochemical degradation occurring when dissimilar metals contact in saliva

Answer

Galvanic corrosion occurs when two dissimilar metals are in electrical contact via saliva, creating a battery-like cell that corrodes the more anodic metal.

Question 5

Which characteristic distinguishes Type IV gold alloys from Type I gold alloys?

Accepted Answer

Type IV alloys are harder and used for partial denture frameworks

Answer

Type IV gold alloys have the highest hardness and strength among the four types, making them suitable for partial denture frameworks and thin castings requiring durability.

ADEX - Dental Hygiene Exam Practice Test

ADEX - Dental Hygiene Exam Practice Test

ADEX Dental Biomaterials 3