NBDHE Dental Materials and Procedures Flashcards

Which component of composite resin is responsible for coupling the filler particles to the resin matrix?

Answer: Silane coupling agent

The silane coupling agent chemically bonds the inorganic filler particles to the organic resin matrix, improving the mechanical properties of the composite.

What is the primary reason that bonding agents are applied in multiple coats when using total-etch technique?

Answer: To compensate for oxygen inhibition of the outer layer

The outermost layer of bonded resin remains uncured due to oxygen inhibition, so multiple coats ensure a fully polymerized bonding layer beneath.

Galvanic shock between two dissimilar metals in the mouth occurs due to which electrochemical process?

Answer: Current flow from the less noble to the nobler metal through the electrolyte

When two dissimilar metals contact in saliva (an electrolyte), current flows from the less noble (anode) to the nobler metal (cathode), causing the patient to feel a galvanic shock.

When using alginate impression material, what is the effect of using warmer water during mixing?

Answer: Decreases setting time

Warmer water accelerates the chemical reaction in alginate, decreasing the setting time and reducing the working time available to the clinician.

Which cement is most biocompatible and has the ability to release fluoride, making it ideal under restorations near the pulp?

Answer: Glass ionomer cement

Glass ionomer cement releases fluoride, has good biocompatibility, and bonds chemically to tooth structure, making it an excellent liner or base near the pulp.

What is the purpose of the 'sand blasting' (air abrasion) step when bonding to metal surfaces of a PFM restoration?

Answer: To remove the oxide layer and increase micromechanical retention

Air abrasion with aluminum oxide removes surface contaminants and creates micromechanical retention by roughening the metal surface prior to bonding.

A denture processed using the compression molding technique shows internal porosity. What is the most likely cause?

Answer: Processing at too high a temperature causing boiling of monomer

If the processing temperature exceeds 100°C, the residual monomer (boiling point ~100.3°C) vaporizes and creates internal gaseous porosity in the acrylic.