Dental practices may contain viruses and bacteria that can cause the transfer of infections from one patient to another or from patients to staff. This is known as cross infection and it may occur through direct contact between patients and staff or through the use of infected instruments. The goal when sterilizing instruments is to prevent micro-organisms from being transferred, thus ensuring that the instruments and materials are safe and protecting both the patients and the staff.

All of the work surfaces and instruments used must be disinfected and sterilized. It is necessary to cover all areas where pathogenic agents may be found. Chemical disinfectants should be used for surfaces and physical disinfection and sterilization methods should be used for instruments. Autoclaves are normally utilized in the latter case because they can sterilize glass, metal and fabrics. Using saturated, pressurized steam is quick, cheap and non-toxic. For effective sterilization of all pathogenic agents, the required times are 20 minutes at 121°C and 1 atmosphere or 7 minutes at 134°C and 2 atmospheres.

In dental practices, the person in charge of managing sterilization and decontamination procedures is the dental assistant. It is necessary to have good knowledge of microbiology and how disinfectants work in order to be fully conscious of everything that needs to be done in the steps before the actual sterilization process:

• Decontamination.
• Cleaning (by hand, with ultrasonic equipment, with washer disinfectors).
• Rinsing.
• Drying.
• Packaging (which includes maintaining and checking instruments, bagging them and loading the autoclave).

Another key factor in effective sterilization is the duration of disinfection cycles. The times are standardized by special protocols which must be respected or the procedure will not be completed successfully, as some spores can survive for a number of minutes at very high temperatures. Timing is crucial in dental practices. The availability of medical instruments is partly based on the sterilization cycle times, which cannot be cut.

However, might it be possible to get the same results from shorter sterilization cycles? Short sterilization cycles can be run in special cutting-edge autoclaves that use moist heat. They can reduce the duration of sterilization cycles by up to 35%, thus cutting overall costs and improving productivity.

There are also practical, low-cost microwave techniques that are based on thermal and non-thermal effects: the thermal effect involves the generation of molecular vibrations that increase the temperature and kill micro-organisms, while the non-thermal effect is caused by high-energy electromagnetic waves that alter the molecular structure of pathogens, thus killing them. Both effects offer maximum safety. This sterilization method can be used for all materials and a full cycle lasts approximately 4 minutes.

So, shorter sterilization cycles are possible, but only with specialist class B autoclaves or alternative methods. It is not advisable to take measures on your own to shorten sterilization procedures because the risk of transferring infectious micro-organisms would be very high.