Dental Materials & Technology Flashcards

Which polymerization mechanism is used in dual-cure resin cements?

Answer: Both light and chemical cure

Dual-cure resin cements combine light-activated and self-curing (chemical) polymerization to ensure adequate cure in areas light cannot penetrate.

What is the primary advantage of zirconia over porcelain-fused-to-metal (PFM) crowns?

Answer: No metal substructure eliminating gray gingival margin

Zirconia crowns eliminate the dark metal margin visible at the gingival tissue that can occur with PFM restorations.

Which bonding agent generation uses a separate etch, primer, and adhesive in three distinct steps?

Answer: 4th generation

4th generation adhesives use a three-step process: phosphoric acid etch, primer application, and then adhesive bonding agent.

The water-to-powder ratio of dental gypsum products directly affects which property?

Answer: Setting expansion and strength

Increasing water-to-powder ratio produces a weaker, more porous gypsum product with reduced setting expansion.

Which impression material requires a custom tray to minimize volumetric distortion?

Answer: Zinc oxide eugenol paste

Zinc oxide eugenol impression paste flows readily and requires a custom tray to control thickness and prevent distortion.

What does the Shore A hardness scale measure in dental elastomers?

Answer: Resistance to permanent indentation

Shore A hardness quantifies an elastomer's resistance to permanent indentation by a standardized probe under specified load.

Which ceramic system is most appropriate for a high-strength posterior three-unit fixed partial denture?

Answer: Zirconia-based ceramic

Zirconia offers flexural strength exceeding 900 MPa, making it the material of choice for multi-unit posterior bridges where fracture risk is highest.