AGD Dental Materials & Technology 2 — Questions and Answers
Question 1: Which polymerization mechanism is used in dual-cure resin cements?
- Chemical cure only
- Light cure only
- Both light and chemical cure (Correct answer)
- Heat cure only
Correct 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.
Question 2: What is the primary advantage of zirconia over porcelain-fused-to-metal (PFM) crowns?
- Superior esthetics in all situations
- Higher translucency
- No metal substructure eliminating gray gingival margin (Correct answer)
- Lower cost
Correct 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.
Question 3: Which bonding agent generation uses a separate etch, primer, and adhesive in three distinct steps?
- 4th generation (Correct answer)
- 6th generation
- 7th generation
- 8th generation
Correct answer: 4th generation
4th generation adhesives use a three-step process: phosphoric acid etch, primer application, and then adhesive bonding agent.
Question 4: The water-to-powder ratio of dental gypsum products directly affects which property?
- Color stability
- Setting expansion and strength (Correct answer)
- Radiopacity
- Biocompatibility
Correct answer: Setting expansion and strength
Increasing water-to-powder ratio produces a weaker, more porous gypsum product with reduced setting expansion.
Question 5: Which impression material requires a custom tray to minimize volumetric distortion?
- Alginate
- Zinc oxide eugenol paste (Correct answer)
- Addition silicone (vinyl polysiloxane)
- Polyether
Correct answer: Zinc oxide eugenol paste
Zinc oxide eugenol impression paste flows readily and requires a custom tray to control thickness and prevent distortion.
Question 6: What does the Shore A hardness scale measure in dental elastomers?
- Surface roughness
- Resistance to permanent indentation (Correct answer)
- Elastic modulus
- Tear strength
Correct answer: Resistance to permanent indentation
Shore A hardness quantifies an elastomer's resistance to permanent indentation by a standardized probe under specified load.
Question 7: Which ceramic system is most appropriate for a high-strength posterior three-unit fixed partial denture?
- Feldspathic porcelain
- Leucite-reinforced glass ceramic
- Zirconia-based ceramic (Correct answer)
- Fluorapatite ceramic
Correct 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.
AGD Dental Materials & Technology 2
Which polymerization mechanism is used in dual-cure resin cements?