EFDA Dental Materials & Equipment Maintenance 2 — Questions and Answers
Question 1: Which type of composite resin is best suited for high-stress posterior restorations?
- Flowable composite
- Hybrid composite (Correct answer)
- Microfill composite
- Ormocer composite
Correct answer: Hybrid composite
Hybrid composites contain both macrofillers and microfillers, providing the strength needed for posterior load-bearing restorations.
Question 2: What is the primary purpose of a dentin bonding agent in composite restorations?
- Increase the opacity of the composite
- Provide antimicrobial properties to dentin
- Create a micromechanical bond between composite and tooth structure (Correct answer)
- Reduce polymerization shrinkage
Correct answer: Create a micromechanical bond between composite and tooth structure
Dentin bonding agents infiltrate demineralized dentin to form a hybrid layer that creates micromechanical retention for composite resin.
Question 3: When mixing zinc oxide eugenol (ZOE) cement, which consistency is appropriate for a temporary restoration?
- Thin, watery consistency
- Putty-like consistency (Correct answer)
- Heavy, stiff consistency
- Stringy, cobwebbing consistency
Correct answer: Putty-like consistency
A putty-like consistency is used for ZOE temporary restorations, allowing it to be condensed into the cavity preparation.
Question 4: Which component of a dental unit waterline biofilm poses the greatest infection control concern?
- Legionella pneumophila
- Pseudomonas aeruginosa (Correct answer)
- Streptococcus mutans
- Candida albicans
Correct answer: Pseudomonas aeruginosa
Pseudomonas aeruginosa is a commonly isolated opportunistic pathogen from dental unit waterlines and is an infection control concern especially for immunocompromised patients.
Question 5: What is the recommended water quality standard for dental unit waterlines according to the CDC?
- <500 CFU/mL
- <200 CFU/mL (Correct answer)
- <100 CFU/mL
- <50 CFU/mL
Correct answer: <200 CFU/mL
The CDC recommends that dental unit waterline output water contain no more than 500 CFU/mL of heterotrophic water bacteria, consistent with drinking water standards.
Question 6: Which type of impression material is considered irreversible hydrocolloid?
- Agar hydrocolloid
- Alginate (Correct answer)
- Polyvinyl siloxane
- Zinc oxide eugenol paste
Correct answer: Alginate
Alginate is an irreversible hydrocolloid because its gelation is a chemical reaction that cannot be reversed by temperature changes.
Question 7: When should the curing light tip be cleaned during a clinical day?
- Only at the start of the day
- Only at the end of the day
- Between each patient (Correct answer)
- Once per week
Correct answer: Between each patient
Curing light tips must be disinfected or sterilized between patients to prevent cross-contamination.
EFDA Dental Materials & Equipment Maintenance 2
Which type of composite resin is best suited for high-stress posterior restorations?