AWD and Sterilisation

Question 1

Do you have to use the automatic washer disinfector?

Answer 1

Yes - it is a legal requirement to process contaminated instruments through it

Question 2

Why is using the AWD the preferred method or cleaning dental instruments?

Answer 2

• it offers the best option for the control and reproducibility of cleaning and the cleaning process can be validated.
• It carries out the process of cleaning and disinfection consecutively

Question 3

What are the steps in a typic WD cycle?

Answer 3

1 - Flush 
2 - Wash 
3 - Rinse 
4 - Thermal disinfection 
5 - Drying

Question 4

Describe the flush step of the AWD. What should the water temp be and why?

Answer 4

• Removes ‘difficult’ gross contamination, including blood, tissue debris, bone fragments and other fluid and solid debris
• water temperature of <45°C is used to prevent protein coagulation and fixing of soil to the instrument.

Question 5

Describe the wash step of the AWD. What must the detergents in this step used be?

Answer 5

• Removes any remaining soil
• Mechanical and chemical processes loosen and break up contamination adhering to the instrument surface

-The detergent must be specified by the manufacturer as suitable for use in a WD

Question 6

Describe the rinsing stage of the AWD.

Answer 6

-Removes detergent used during the cleaning process. -this stage can contain several substages.

Question 7

Describe the thermal disinfection stage of the AWD.

Answer 7

The temperature of the load is raised and held at the pre-set disinfection temperature for the required disinfection holding time: for example, 80˚C for 10 minutes, or 90˚C for 1 minute.

Question 8

Describe the drying stage of the AWD

Answer 8

Purges the load and chamber with heated air to remove residual moisture.

Question 9

What needs to be done after the instruments are processed through the AWD?

Answer 9

Need to be inspected to see if there is any visible contamination present

Question 10

How are instruments inspected after going through the AWD?

Answer 10

Inspected using an illuminated magnifier

Question 11

What should be done if visible contamination is identified upon examination after being processed through the AWD?

Answer 11

The instrument should be manually washed then put back in the washer disinfector (because need the thermal disinfection stage again)

Question 12

After inspection (and no contamination present), what is the next step in the decontamination process?

Answer 12

Prepping equipment for sterilisation

Question 13

Why is steam used in the sterilisation process?

Answer 13

We use steam in the sterilisation process as it:
• Carries a lot of energy
• Is non-toxic
• The main ingredient is water which is readily available
• There is no waste product except water

Question 14

What kind of water needs to be used for the sterilisation process?

Answer 14

Purified water as all the particulate has been removed

Question 15

How is pressure created from steam in small spaces?

Answer 15

The steam produced from water will be in excess of 1000x the water volume. This will create pressure in confined space and is good as only a small volume of water is required to fill up the chamber for sterilising

Question 16

What are the 3 main types of sterilisers found in the dental environment?

Answer 16

• Type N
• Type B
• Type S

Question 17

Describe the Type N Steriliser and how it works.

Answer 17

• The machine heats water in the chamber and as it turns to steam it passively forces the air from the chamber
• The process isnt entirely efficient and can leave pockets of air within the chamber

Question 18

What instruments cant be processed in the Type N steriliser?

Answer 18

can’t process wrapped instruments or channelled or lumened instruments

Question 19

Why are the possible air pockets left in the Type N steriliser a problem?

Answer 19

The problem with pockets of air is because air cannot be heated or maintain temperature like steam can (it is always at a lower temp than the surrounding steam). If any instruments are in contact with the air and not steam then it might not reach its sterilisation temperature for the minimum time required.

Question 20

As the cycle in the type N steriliser isnt entirely efficient, it is only recommended to process what kinds of instruments?

Answer 20

‘rigid steel instrumentation with no pockets, channels or lumens’ and don’t process wrapped instrumentation

Question 21

All 3 types of sterilisers need to reach what temperature and hold it for how long?

Answer 21

134-137 degrees Celsius and hold for a min of 3 mins

Question 22

Describe how the Type B steriliser works.

Answer 22

• First step removes all the air from the chamber using a vacuum pump
• Then fills the chamber with steam
• Because the air has been removed, a vacuum (negative pressure) has been created which allows the steam to rush into the chamber
• This means that the steam effectively contacts all the surfaces of what is being processed
• Has a drying stage at the end to remove any remaining moisture

Question 23

What instruments can be processed through the Type B Steriliser?

Answer 23

• Because of the vacuum, can process ‘wrapped, channelled and lumened instruments’. Can also process items such as cotton wool swabs.

Question 24

What does a Type S steriliser process?

Answer 24

• It can only be used for the equipment it is designed to process and must follow manufacturer’s recommendations.

Specialised for handpieces ect

Question 25

What are the components of sinner circle? Why is this relevant

Answer 25

• chemicals
• temperature
• energy
• time

If any of these quarters are decreased or increased then it will impact on what % they play in the process

Question 26

How do detergents work?

Answer 26

hydrophilic and hydrophobic ends

Question 27

What diff types of detergents are used in the decontamination process and for what purposes?

Answer 27

o High and low alkaline detergents for enclosed purposes (not in contact with skin)
o Enzymatic detergent – breaks down proteins (ultrasonic and sometimes manual washing)
o pH neutral – less harmful to skin (manual washing as high chance of skin contact)