Steam sterilization

    Sterilization completely eliminates or destroys all living microorganisms and their spores in order to prevent disease transmission with the use of instruments. Comparing to many different methods available for sterilization, the techniques using saturated steam under pressure is the most reliable and should be used whenever possible on all critical and semi-critical items that are heat and moisture resistant. Saturated steam under pressure in an autoclave achieves their destruction by the irreversible coagulation and denaturation of enzymes and structural proteins. The two common types of steam sterilizers (autoclaves) are the gravity displacement autoclave and the high-speed prevacuum sterilizer.

Dental Autoclave [1]

    The basic principle of steam sterilization is to expose each instrument to steam directly at the specific temperature and pressure for an adequate time. According to the basic principle, there are four parameters of steam sterilization: steam, pressure, temperature and time.

    The ideal steam for sterilization is dry saturated steam. Pressure can help quickly obtain the requiring high temperature to kill microorganisms. Specific temperatures must be achieved to ensure the microbicidal activity. The two common steam-sterilizing temperatures are 121^oC and 132^oC. These temperatures must be maintained for a minimal time to kill microorganisms. The sterilization periods varies with the temperatures, the lower the temperature the longer the exposure time. In general, the minimal time for wrapped items are 30 minutes at 121^oC in a gravity displacement sterilizer or 4 minutes at 132^oC in a prevacuum sterilizer.

Steam Sterilization Phases [2]

Understanding steam sterilization

See more information on these links:
1. Centers for Disease Control and Prevention
2. Gravity v.s Vacuum System
3. UNC environment. Health and Safety

Picture resources:
1.http://www.medicalexpo.com/prod/sirona-dental-systems/dental-autoclave-bench-top-vacuum-cycle-70662-470828.html
2.http://www.gdnash.com/sterilization/