EFDA Dental Materials & Equipment Maintenance 3 — Questions and Answers
Question 1: Which dental material is most susceptible to moisture contamination during placement?
- Glass ionomer cement
- Zinc phosphate cement
- Composite resin with total-etch technique (Correct answer)
- Zinc oxide eugenol cement
Correct answer: Composite resin with total-etch technique
Composite resin placed with total-etch technique requires a dry field because moisture contamination disrupts the bonding agent and weakens adhesion.
Question 2: What is the purpose of silane coupling agent when bonding to ceramic restorations?
- Increase the translucency of the ceramic
- Create a chemical and micromechanical bond between ceramic and resin cement (Correct answer)
- Reduce the viscosity of the luting cement
- Prevent staining of the ceramic surface
Correct answer: Create a chemical and micromechanical bond between ceramic and resin cement
Silane creates a chemical bond between the inorganic ceramic surface and the organic resin cement by acting as a bifunctional molecule.
Question 3: Which handpiece maintenance step must be performed BEFORE sterilization?
- Lubrication of internal bearings (Correct answer)
- Flushing with water for 20-30 seconds
- Testing the spray patterns
- Running the handpiece at full speed
Correct answer: Lubrication of internal bearings
Handpieces must be lubricated before sterilization so the lubricant can penetrate internal components; autoclaving without lubrication can damage bearings.
Question 4: What does the term 'working time' refer to for dental cements?
- The time from mixing until the material is fully set
- The time available from mixing until insertion must be completed (Correct answer)
- The time required for the material to reach final strength
- The shelf life of the material after opening
Correct answer: The time available from mixing until insertion must be completed
Working time is the period after mixing begins during which the material remains workable and must be inserted into the prepared tooth or appliance.
Question 5: Which infection control protocol applies to extracted teeth used for study or practice?
- Store in dry containers at room temperature
- Treat as sharps and decontaminate with 10% sodium hypochlorite (Correct answer)
- Sterilize in autoclave only without prior cleaning
- Dispose in regular waste immediately after extraction
Correct answer: Treat as sharps and decontaminate with 10% sodium hypochlorite
Extracted teeth are regulated medical waste and must be treated with sodium hypochlorite or equivalent disinfectant before handling as study models, per OSHA Bloodborne Pathogens Standard.
Question 6: When mixing glass ionomer cement for luting, which ratio produces the correct consistency?
- Equal parts powder and liquid
- Manufacturer's specified powder-to-liquid ratio (Correct answer)
- Higher powder to decrease solubility
- Higher liquid to increase flow
Correct answer: Manufacturer's specified powder-to-liquid ratio
Glass ionomer cement must be mixed at the manufacturer's specified powder-to-liquid ratio to achieve the correct viscosity, strength, and fluoride release.
Question 7: What is the primary advantage of self-adhesive resin cements over conventional resin cements?
- Superior esthetic results
- No etching or bonding agent is required prior to cementation (Correct answer)
- Greater fluoride release
- Higher compressive strength
Correct answer: No etching or bonding agent is required prior to cementation
Self-adhesive resin cements contain acidic monomers that simultaneously etch and bond to tooth structure, eliminating the need for separate etching and priming steps.
EFDA Dental Materials & Equipment Maintenance 3
Which dental material is most susceptible to moisture contamination during placement?