For which device is a 20-minute cycle commonly specified?

• A. Autoclave
• B. Glass bead steriliser
• C. UV Sterilisation
• D. None

Answer: (A)

The device that commonly has a specified 20-minute cycle uses steam under pressure to achieve sterilization. In many healthcare and dental settings, a standard cycle runs about 20 minutes at 121°C for wrapped instruments, providing enough time for heat and moisture to penetrate and kill spores and other microbes. This fixed-cycle approach is a hallmark of autoclaves, which rely on defined time, temperature, and pressure to ensure sterility.

Glass bead sterilizers are quick-handling devices, typically used for rapid surface sterilization of individual items and finish in just a few minutes, not 20. UV sterilization depends on exposure to UV-C light and is governed by factors like exposure time, distance, and shadowing rather than a fixed 20-minute cycle; its effectiveness for instrument sterilization is more variable and not standardized around a 20-minute cycle. None fits this standard as well as the autoclave, which is why the 20-minute cycle is most closely associated with it.