Which method of sterilization is recommended for unpackaged instruments?

• A. Dry heat sterilization
• B. Boiling water
• C. Autoclave 250F with 15psi for 15 minutes
• D. Chemical sterilant

Answer: (C)

Moist heat under pressure is the most reliable way to sterilize unpackaged instruments. The autoclave uses steam plus pressure to reach high, continuous temperatures that penetrate all instrument surfaces and reliably kill spores and other microorganisms. For unwrapped items, a cycle of 250°F (121°C) at 15 psi for about 15 minutes provides an effective balance of thorough sterilization with a practical turnaround, since there’s no packaging that would slow heat and moisture penetration.

Dry heat sterilization would require much higher temperatures and much longer times, and can be harsher on instruments, making it less efficient for routine use with unpackaged metal tools. Boiling water lacks the pressure and the sustained high heat needed to achieve true sterilization, so spores can survive. Chemical sterilants involve prolonged immersion and are typically used for heat‑sensitive items that can’t withstand high temperatures, plus they require rinsing and handling precautions that aren’t ideal for routine immediate-use instruments.

So, the autoclave cycle described provides rapid, reliable sterilization for instruments ready to use, ensuring they’re free of viable microorganisms before patient contact.