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Overview of Sterilization

Hand removing products from sterilization test unit

Here’s our overview of sterilization in an easy to read FAQ style:

Why is sterilization of instruments critical to a dental practice?

It’s first and foremost about patient safety! Whether you operate in Canada or USA, we all have to ensure we follow the strictest sterilization procedures and quality standards our dental license demands.

What’s involved in sterilization?

Cleaning and sterilization usually involves a strict multi-step procedure that ensures all microorganisms that are attached to your instruments are destroyed and that sterility is achieved and maintained. This means all surfaces of the instruments must be completely clean and free of debris. Your process should be part of your overall Dental Management Program that outlines the number and capacity of sterilization equipment and instruments, patient volume, and dental appointment times. More importantly, allow ample time in your schedule to follow manufacturers’ recommended disinfection wait times and turnaround times for sterilization.

What happens if we don’t achieve and maintain sterility?

Poor sterilization means you can contaminate your instruments which in turn can spread deadly infections amongst multiple patients. Your procedures should include monitoring and testing of your sterilization process.

Why is sterilization record keeping an essential process?

While keeping records can be a painstaking process, Sowingo’s new app will streamline the process for you. Best practice record keeping means your records are easily identified, filed, protected and controlled throughout the lifecycle of the process. These records are critical because they contain the history of your dental sterilization process. In summary, your records need to include things like: For each sterilization cycle, record the type of sterilizer and cycle used; the load identification number; the load contents; the exposure parameters (e.g., time and temperature); the operator’s name or initials; and the results of mechanical, chemical, and biological monitoring.

Why is cleaning critical before sterilization?

An effective cleaning process needs to remove blood or debris on the instruments. Unclean instruments can prevent steam or unsaturated chemical vapor from contacting the instrument surfaces to achieve sterilization.

Manual cleaning should only be done on those instruments that are hard to clean using other methods. High chance of injury and cross infection! **

Ultrasonic cleaning involves a machine that uses turbulence to create continuously imploding bubbles. It’s the vibration from these bubbles that helps remove debris from the instruments. You can place the instruments in your machine loosely or used specially designed instrument cassettes (newer designs have vents to ensure maximum exposure to the cleaning solution). This method means reduced contact with contaminated instruments and, therefore, less chance of cross infection.

Instrument washers are used to clean dental instruments. After the instruments are placed inside they are exposed to a spray mixture of water-detergent solution. Then they are thoroughly cleaned by a pressurized stream of cleaning liquid. This is a popular choice as you can clean a lot of instruments at once.

What are the main sterilization techniques for dental instruments?

Here are the main methods used to sterilize dental instruments.

Autoclave machines use an autoclave chamber filled with pressurized steam for a set time period. To achieve sterilization the air inside the autoclave is completely evacuated, either by displacing the air already present inside the chamber with steam (gravity displacement), or air is evacuated through a vacuum and then the steam is introduced. Instruments are placed in packages and allowed to dry completely before they are taken out of the autoclave.

Dry heat ovens are electrical and use dry heat to sterilize dental instruments. Dry heat ovens don’t use pressure and are safer than steam autoclaves. Heat is electrically controlled so sterilization temperatures can be attained rapidly. However, they may not be able to completely kill all microbes, such as prions. Dry heat ovens are used to sterilize the instruments that do not get burned during heating, such as glass slabs or powders.

Chemical vapor sterilization uses a mixture of various chemicals—such as alcohol, ketones, formaldehyde, and water—which is heated under pressure to form a sterilization gas. A typical sterilization procedure requires 20 minutes to complete at 270ᵒ F under a pressure of 20 psi.

Cold sterilization is used for heat-sensitive dental instruments. Solutions such as glutaraldehyde or sodium hypochlorite may be used for this purpose. This procedure requires quite a bit of time to complete the entire sterilization process.

What types of sterilization tests are out there?

Here are just a few of the more common tests used in a dental practice. The following information is sourced from the Centers for Disease Control (USA) –

Sterilization procedures should be monitored using biological, mechanical, and chemical indicators.

Biological indicators, or spore tests are the most accepted means of monitoring sterilization because they assess the sterilization process directly by killing known highly resistant microorganisms (e.g. Geobacillus or Bacillus species). However, because spore tests are only done weekly and the results are usually not obtained immediately, mechanical and chemical monitoring should also be done.

Mechanical and chemical indicators do not guarantee sterilization; however, they help detect procedural errors (e.g., overloaded sterilizer, incorrect packaging) and equipment malfunctions. Mechanical and chemical monitoring should be done for every sterilizer load. Mechanical monitoring involves checking the sterilizer gauges, computer displays, or printouts, and documenting in your sterilization records that pressure, temperature, and exposure time have reached the levels recommended by the sterilizer manufacturer. Since these parameters can be observed during the sterilization cycle, this might be the first indication of a problem.

Chemical monitoring uses sensitive chemicals that change color when exposed to high temperatures or combinations of time and temperature. Examples include chemical indicator tapes, strips, or tabs and special markings on packaging materials. Chemical indicator results are obtained immediately following the sterilization cycle and therefore can provide more timely information about the sterilization cycle than a spore test. A chemical indicator should be used inside every package to verify that the sterilizing agent has penetrated the package and reached the instruments inside. If the internal chemical indicator is not visible from the outside of the package, an external indicator should also be used. Chemical indicators help to differentiate between processed and unprocessed items, eliminating the possibility of using instruments that have not been sterilized.

Do not use instrument packages if mechanical or chemical indicators indicate inadequate processing. Chemical indicators should be inspected immediately when removing packages from the sterilizer; if the appropriate color change did not occur, do not use the instruments.

Useful Links
Health Canada
NDEB National Dental Examining Board of Canada
USA CDC Centers for Disease Control and Prevention – Oral Health Page Link
USA OSHA Occupational Safety and Health Administration
OSHA A Guide to Compliance with OSHA Standards

Canada Regional Links
Alberta Health Service
British Columbia Dentistry
New Brunswick Government
Newfoundland and Labrador
Nova Scotia Infection and Prevention Guidelines
Ontario Royal College of Dental Surgeons of Ontario
Prince Edward Island Dental Council


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