Dental Materials and Infection Control / Patient Safety
What this domain tests
This domain tests material selection, handling, biocompatibility, sterilization, disinfection, sharps safety, waste segregation, and medical emergency preparedness. Items often ask which material property or infection-control step prevents a specific failure.
Core rules and concepts
- Composite polymerization shrinkage creates contraction stress, especially in high C-factor cavities. Incremental layering and appropriate curing reduce stress. Glass ionomer releases fluoride and bonds chemically but is weaker than composite.
- Amalgam has good compressive strength but no adhesive bond; it requires retention and careful waste management. Do not place amalgam waste in general trash.
- Elastomeric impression materials differ in dimensional stability; alginate is less stable and should be poured promptly.
- Standard precautions apply to all patients. Hand hygiene, gloves, eye protection, and mask are baseline. Sharps must not be recapped by hand.
- Sterilization by autoclave commonly uses 121 degrees Celsius for about 15 minutes or 134 degrees Celsius for about 3 to 4 minutes; biological indicators verify effectiveness. Chemical disinfectants are not substitutes for sterilization of critical items.
- Needlestick injuries require immediate washing, reporting, and exposure assessment.
- Patient safety includes oxygen, epinephrine, aspirin, and a practiced emergency plan.
Worked example
A large posterior composite has a high C-factor. The reasoning is that shrinkage stress can pull the bond and cause marginal leakage or sensitivity. Use incremental placement and controlled curing rather than one bulky increment; select a bulk-fill material only when its depth of cure and indication are appropriate.
Traps that cost marks
Do not treat disinfectants as sterilants. Do not recap needles by hand. Not all plastics are autoclave-safe. Do not assume a sterilization indicator guarantees sterilization without correct loading and cycle validation. Also avoid mixing sodium hypochlorite and chlorhexidine.