The quick answer to this question is no. There is no form of sterilisation that can achieve complete sterilisation.

However, there are some types of sterilisation techniques that come close. For example, the steam autoclave machine can achieve as close to 100% sterilisation as possible.

Sterilisation techniques that are not as effective as the steam autoclave machine include:

1. wet sterilisation like boiling
2. steam sterilisation by reaching inappropriate temperatures
3. sterilisation with chemical agents such as alcohol, hydrogen peroxide or chlorine bleach.

So, how do autoclaves provide better sterilisation compared to these other techniques?

1. Autoclaving vs. wet sterilisation

Boiling water reaches a temperature of 100°C. Many microorganisms that are invisible to the human eye, such as bacteria, viruses and spores, can survive at this temperature.
Although boiling instruments and other items is widely considered sufficient, autoclaves reach temperatures of 121°C.
This temperature is effective in destroying all types of microorganisms.
In addition to this, sterilisation techniques that leave items moist at the end of the sterilisation process also expose them to microorganisms.
Bacteria and spores are particularly attracted to moisture.
Autoclaves sterilise items in a closed environment and allow the sterilised items to remain in this sterilised environment until they are dry.
Thus, autoclaves are much more successful in providing sterilisation than boiling.

2. Autoclaving vs. steam sterilisation

The steam autoclave machine uses steam rather than boiling water to achieve higher temperatures. Steam can only be produced at temperatures above 100°C.
However, not all steam sterilisation processes can reach the ideal temperature of 121°C, which is considered ideal for the elimination of all microorganisms.
The use of pressure to generate steam is what allows autoclaves to produce steam at higher temperatures.
Most types of steam sterilisation techniques also result in condensation, leaving the items being sterilised moist and exposed to microorganisms.
Whether these items are air dried or artificially dried, once the steaming process is complete, the items are no longer sterile.
Items are placed in sterile sleeves or envelopes to ensure that the sterilising effect of the autoclave is maintained once they leave the sterile environment a further limit to exposure.
However, steam sterilisation is still considered to be superior to boiling sterilisation, but not as effective as sterilisation in an autoclave.

3. Autoclaving vs. chemical sterilisation

Most medical and other industries use chemicals as their primary means of disinfection, especially when it comes to keeping large areas such as operating theatres and research areas clean and free of contaminants and microorganisms.
However, chemical cleaners are far less effective than autoclaving, as many types of microorganisms simply cannot be eliminated by specific chemicals.

Common chemical agents used for disinfection include:

1. Chlorine bleach
2. Hydrogen peroxide
3. Sterile alcohol
Chemical sterilisation is also not as effective as boiling or other forms of steam sterilisation.

Sterilisation processes often need to be repeated frequently in order to provide a consistent but limited sterilisation effect.
There are some sterilisation techniques that allow dehydrogenation and are therefore considered more effective than autoclaving.
However, these techniques are costly and are not suitable for sterilisation in all industries. For example, radiation is effective in destroying pyrogens, but may expose the item being sterilised to radiation and is therefore not considered a suitable method of sterilisation.

Pyrogen removal is the process of eliminating toxic pyrogens.
Pyrogens are excretions excreted by bacteria that can survive in the pressurised environment of high temperatures and autoclaves.
Although these pyrogens may be harmful to humans, they are not destroyed in an autoclave like bacteria and other microorganisms, nor do they cause harm.
Items sterilised directly after use are exposed to fewer bacteria for a shorter period of time, reducing the risk of pyrogens.
Therefore, ensuring that instruments, equipment and other items are regularly sterilised ensures that the autoclave is as 100% effective as possible.