31 Jan 2019

Preventing the spread of infection in dental practices

There is currently a silent battle in every healthcare environment all over the world: the war against micro-organisms. For both patients and staff alike, micro-organisms must be destroyed in order to prevent the spread of infections. An important example of this is the fight against Healthcare-Associated Infections (HAIs), infections that patients are exposed to as a result of their visit in the hospital. This may be due to contaminated equipment, surgical instruments, or improper staff hygiene.

To know more about the health-care-associated infections (HAIs):



Every dental and healthcare practice must have a battle plan to prevent the spread of HAIs (Healthcare-Associated Infections). The micro-organism warfare strategy consists of three processes, done in the following order: cleaning, disinfection, and sterilisation. Let’s take a look at these one by one, going from a mild cleaning system to the strongest one (sterilisation).

1.   Cleaning

When we use the term “cleaning”, we define this as the removal of all visible dirt, dust or other foreign debris. This means that the equipment that has been cleaned by hand with soap/detergent and water is free of all physical and chemical residues and of most microorganisms.

The goal of cleaning is to reduce the bioburden. The bioburden (or initial contamination) refers to the population of viable organisms on a material, instrument, product or package. Depending on where and how the item will be used, cleaning may be enough to reduce the bioburden, but for most other types of dental equipment, cleaning is only the first step, which will be followed either by disinfection alone (or disinfection and then sterilization). In other words, cleaning is always the first step in the subsequent disinfection and sterilization of equipment.

There are five main reasons why cleaning all dental equipment is so crucial:

  • It gets rid of all blood, dirt or foreign particles that are left, which may cause dangerous complications for the next person to be operated on using that instrument.
  • It reduces the bioburden.
  • It takes away the breeding ground of surviving micro-organisms.
  • It prevents the corrosion of highly precise and expensive tools, which have delicate hinges and pivots.
  • It ensures the safe transfer of equipment to be assembled and packaged for disinfection or sterilization.

Some equipment can’t be submerged into water (for example dental handpieces). However for other dental equipment which can - ultrasonics cleaners are the adequate solution. The ultrasonic cleaning process is used in conjunction with solutions in suitable carrier liquids (often water). As the ultrasonic-induced cavitation occurs, the effectiveness of the aqueous solution is greatly improved to deliver an outstanding cleaning outcome.

How do Ultrasonic cleaners work?  

Ultrasonic cleaners employ oscillating sound pressure waves at frequencies beyond those perceptible by the human ear (ultrasound). As the sound waves act on the tank and agitate the contained liquid, cavitation (the implosion of tiny air bubbles within the liquid) is induced. This acts against contaminants adhered to objects contained in the vessel, separating the two gently, efficiently and precisely compared to other forms of conventional cleaning methods aided by brushes or solvents.

2.    Disinfection

When we use the term disinfection we define this as the destruction of all vegetative (living) microorganisms, without necessarily killing all bacterial spores (a difficult-to-kill form of bacteria which exists in a kind of hibernation state that can withstand tough conditions1). Some types of bacterial spores are very dangerous, e.g. anthrax and tetanus. In order to kill all microorganisms, including bacterial spores, we must use the disinfecting process of sterilisation (see next section).

In regards to the dental industry, thermal disinfectors (which are similar to the appearance of a dishwasher) are recommended. Dental treatment centres and surfaces may be disinfected with chemicals whereas medical equipment may be placed inside an automatic washer machine (think dishwasher for tools instead of dishes). Items that come in contact with bodily fluids are recommended to be disinfected in a “washer disinfector” machine. However, the vast majority of equipment will require disinfection and then sterilization. If you are interested in thermal disinfectors you can check out our SMEG Thermal Disinfector.

The terms disinfection and decontamination

In much of the dental industry, the terms decontamination and disinfection are used interchangeably. The problem with using the term disinfection when referring to dental equipment is that dental equipment cannot actually become infected in the first place; only people (or animals) can! Have you ever heard of a coughing excavator or a feverish handpiece? No! While this term is not strictly correct, it is the one used most often to describe this second stage of the process. And as if that weren’t confusing enough, sometimes decontamination is used as a synonym for disinfection, but sometimes it refers to the whole “decontamination process,” which is another way of saying all three stages of cleaning, disinfection, and sterilization.

3.    Sterilisation

After our equipment has gone through the processes of cleaning and/or disinfection, it is ready for the last step of micro-organism eradication, sterilization (the killing of all microorganisms, including bacterial spores). The World Health Organization (WHO) recommends that all instruments that could possibly come in contact with fluids inside the body should be sterilized before use (ibid.). 

The oldest method of sterilization is open-flaming, in which the item was held over an open flame to kill all micro-organisms (think: cavemen and an animal on a spit over an open fire.). In modern times, thankfully, there are more advanced methods of sterilization such as: 

  • moist heat (e.g steam sterilisation)
  • dry heat (e.g oven)
  • biocide by gas or chemicals
  • radiation

By far, the industry standard for sterilization today is to use pressurized high-temperature steam to kill all microorganisms in a specialized machine called an autoclave. Based on the model of the pressure-cooker, modern autoclaves run various cycles for different types of equipment and materials, as well as liquids. They come in different sizes, from small tabletop microwave oven-sized machines to large hospital elevator-sized machines. Depending on the needs of the practice, there may be one or several autoclaves used on a daily basis to sterilize all equipment used during operations.

Battlefield: The CSSD

In every hospital, there is a special department called the Central Sterile Services Department (CSSD) (or sterile processing department/SPD) where all cleaning, disinfection, and sterilization takes place. Each hospital’s CSSD works hard to ensure that once equipment and materials emerge from the autoclave that they stay sterile until opened in the operating room. There are specific protocols for how instruments must be packaged and handled before and after autoclaving to ensure that the items remain sterile and therefore don’t become recontaminated. This strict method can be applied to dental environments to optimise their infection control procedures. However, if you are referring to the above image, a dental practice will not have this large area – the dental surgery will have a dedicated sterilisation room or area which will consist of a ‘dirty’ section and a ‘clean’ section. Very basic.

A Never-Ending Battle...

Unbeknownst to most hospital patients, the CSSD is where the never-ending battle against the spread of infection takes place on a daily basis. Suited up in their battle gear of scrubs, disposable gloves, caps, and masks, the technicians, as well as dental nurses, begin with their first line of defence, cleaning, which kills most of the disease-causing microorganisms with simple soap and water. Then comes the second line of defence, known as disinfection, which kills all vegetative microorganisms. And finally, we go to the last defence, the take-no-prisoners strike of sterilization. There, in the autoclave, every last bit of microorganism, including the stubborn bacterial spore, is annihilated. The CSSD technician carefully stores the package of freshly sterilized tools until they are needed for the next life-saving operation in the hospital. Mission accomplished.

Check out our third post in this series, “What is an Autoclave?” in which we will delve deeper into the concepts of autoclaving, finding out how and why they work. If you have any further questions please contact GUNZ Dental customer service on 1800 025 300.

Check out the Autoclave Sterilisation Basics series from the Sterilisation and Infection Control blog by Tuttnauer.

Click here to visit the Tuttnauer website for more information!

1 Huys, Jan. Sterilization of Medical Supplies by Steam. mhp Verlag GmbH and Heart Consultancy, Wageningen, The Netherlands, 2010.

Recent Posts