Infection control- Top 10

The ultimate essence of dentistry is that all patients should be guaranteed the best possible health care, with the best possible quality and safety to reasonable costs and as few side effects as possible. Quality assurance also includes the evaluation and use of innovative technology. The following products and instruments can ensure that this is achieved.

1. Class B sterilizers

Saturated steam under pressure is by far the quickest, safest and most efficient and most reliable medium for sterilization. Steam sterilizers with class B cycle, in accordance with EN 13060, are very sophisticated medical devices.

Through prevacuum, virtually all air will be evacuated in the chamber and within the goods. Postvacuum will remove all residual moisture from the load. During the vacuum phases the atmospheric pressure in the chamber will be the same as at approximately 30000–40000 meters above sea level! During the sterilization phase the inside pressure on the door to the sterilizer is approximately 2 metric tons. All these extreme forces will put an enormous stress to the chamber material as well as to the vacuum pump and steam generator.

2. Washer disinfectors

Medical devices must be thoroughly cleaned to reduce the bioburden before sterilization. Automated washer disinfectors (thermodisinfectors), fulfiling the requirements in EN 15883, offer the safest, most reliable option. The massive flow of water spraying all items in the washer disinfection process will result in a very effective physical (mechanical) cleaning.

In smaller bench-top washer disinfectors the water flow through the circulation pumps is at least 100 litres per minute. For a complete cycle, this is the equivalent of the water content in 15–25 bath tubs being flushed over the instruments.

In a normal sized hospital washer disinfector, the flow of water through the circulation pumps is at least 400 litres per minute, or 120 bath tubs in a 60 minute cycle. Try to achieve this in manual cleaning!

3. Ultrasonic cleaners

Dental instruments can be very difficult to clean, especially burs and endodontic files. Ultrasonic cleaners, operating in the 35–55 kHz wavelength, can actually tear the biofilm away from the instruments. The low pressure bubbles formed by the high frequency sound waves cause the water to boil at low temperatures and in a microscopic area. The sudden growth and collapse of these vapour cavities cause extreme pressure forces. The lifespan of ultrasonic cleaners is relatively short, lasting anything between 3–5 years.

4. Multipurpose cleaning devices

To clean, disinfect and lubricate hollow instruments, a special device is required. Apart from the primary aim to prevent cross-contamination, another major reason for cleaning is to maintain the instruments. Debris from enamel, dentine, amalgam, composite mixed with oil, saliva and blood can form a grinding smear that will destroy the instruments, causing vibrations that can lead to a risk of bur fractures (which can be inhaled or swallowed by the patient), inferior preparations and loss of sensitivity in the dentist's finger-tips.

5. Waterline cleaning systems

There are recent studies showing that bonding strength is negatively affected by the amounts of bacteria in the dental unit waterline and toxins produced by bacteria in the biofilm are known to cause asthma and allergies — which is proven to be three times as common in dental personnel. The system must clean and disinfect effectively and not being toxic or causing damage to patients, personnel, environment and equipment, therefore the active agent must be both lethal and safe.

6. Compressors 7. Evacuation Systems

The system used should be appropriate for dentistry and able to effectively reduce aerosols created during preparations. In a good suction system the airspeed in the middle of the suction-tip will be approximately 180 kmph. Biofilm in the evacuation system will effectively reduce the airflow and can also retain large amounts of amalgam waste since organic particles are excellent carriers of mercury.

8. Smart tray systems

The logistics of cleaning instruments is time consuming, and the manual handling of instruments during cleaning will cause damage and shorten their lifespan. Shadow effects may easily ensue from the use of solid cassettes, so that the instruments are not being properly cleaned. It is therefore critical to adopt the correct methods to ensure maintenance and efficient cleaning. Instruments should be free and fastened on trays so that ultrasonic waves, water jets and steam can reach every part to clean and sterilize the instruments.

Smart tray systems with 'everything needed for treatment' on the tray facilitates the handling of instruments through the whole cycle. Evaluations of effective tray systems have shown reduced time for handling the instruments at disinfection and sterilization.

9. Face visors

Dental personnel should protect their eyes, noses, mouths and skin of the face from splatter. Paper face masks only protect the nose and mouth for a limited period of time, 5–30 minutes depending on quality. Face visors are a better alternative than face masks and will also reduce waste handling.

10. Alcohol based hand disinfection solutions

There is clear evidence that hand disinfection with alcohol based disinfectant is significantly superior in reducing the bacterial flora to washing with soap and water. To avoid the dehydrating effects on the skin a rehydrating agent is added, usually 1–3% glycerol.

If only one single measure were to be recommended to significantly reduce cross infection — proper hand disinfection is by far the most important.

About the author

Dr Mikael Zimmerman is associate professor and assigned reader in clinical diagnosis at the Karolinska Institutet, Stockholm, Sweden, and is currently affiliated with the Institutet's Department of Clinical Science, division of ENT diseases. He is the author of more than 30 papers on cross-infection control and has authored the Swedish Dental Association's advice on cross-infection as well as the recommendations by the Swedish National Bureau of Health and Welfare on hygiene standards in dental practice.

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