As countries battle a pandemic virus, COVID 19, infection control and sterilization standards are top of mind. Particularly, the dental industry is at the forefront of protecting patients and their staff.

Recent research has shown that Pre & Post-Vacuum (Class A) autoclaves are a more effective way to meet the heightened sterilization standards.

The CDC has yet not adopted the higher standards, which include pre and post vacuum steam sterilization (also known as Class B sterilization). These standards are already widely accepted in other parts of the world (Australia, Europe) and have been integrated in some Canadian provinces.

This article will discuss the necessity for the US to use the Class B pre-vacuum cycle/Class B sterilization method. We'll also examine how the Tuttnauer-T-Edge autoclave was created for the US market.


What is a Pre & Post-Vacuum / Active Air Removal/ Class B Autoclave?

Similar to the invention of the computer desktop, which made it possible for everyone to access the vast data processing power of large data processors that were previously only available to researchers, the Pre & Post –Vacuum autoclave can be used to sterilize patients in smaller sizes.


Why is pre- and post-vacuum autoclaves considered the gold standard?

Active Air Removal is the answer!

Is air bad for you?

Only dry saturated steam can be used to sterilize surfaces. There is nothing that can stop the steam from reaching the sterilized surface.

The majority of equipment we are trying to sterilize has air in it. If this isn't removed, it can act as a barrier and compromise the sterilization process.


Pre-Vacuum and Gravity autoclaves vs. Post-Vacuum autoclaves

There are two main types of steam autoclaves sterilizers, the gravity displacement and high-speed pre- and post-vacuum.

The gravity air removal principle works on the basis of steam being lighter than air. Therefore, it forces air out of the chamber through the drain vent. "Gravity displacement autoclaves are used primarily to process laboratory media, water and pharmaceutical products. Gravity displacement sterilizers have a longer penetration time in porous materials due to incomplete air elimination.

Since non-porous medical instruments are rare, gravity autoclaves are now the most commonly used autoclaves in US dental offices.

Pre- and post-vacuum sterilizers remove air from the chamber using an active vacuum pump. This allows steam to penetrate hollow instruments, ensuring that air is removed from the sterilizing chamber before steam enters.


How does an autoclave Class B remove air?

This can be done in multiple steps.

1. A few vacuum pulses are used to remove air from the chamber.

2. The pressure and temperature of the dental autoclave rise until they reach a constant level. This is known as holding time. This is the moment sterilization actually takes place.

3. The exhaust valve reduces the atmospheric pressure.

4. Finally, the temperature and pressure are further reduced to create a vacuum in the chamber. This allows the water to evaporate and turn into a gas which is then taken out by the vacuum pump.

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