Dentistry – What is Cross Infection?

What is Cross Infection?

Cross infection is the transmission of pathogenic micro-organisms from one person to another. Micro-organisms are living organisms which are microscopic in size, they include;

Fungi – which are treated with anti-fungal agents;

Viruses – which are difficult to treat, many are prevented with vaccination;

Bacteria – which are treated with antibiotics, bacteriocidal agents, and bacterioststic agents

A great number of diseases are caused by micro-organisms contaminating body cells, those that are relevant to dentistry include;


  • Candida albicans – involved in oral thrush and denture stomatitis


  • Hepatitis A, B, C – liver diseases which can be fatal – transmitted through blood
  • Herpes simplex type 1 – involved in cold sores
  • Human immuno-deficiency Virus – can lead to AIDS


  • Streptococcus mutans – involved in dental cairies
  • Staphylococci – involved in gingival and skin boils
  • Porphyromonas gingivalis – involved in periodontal disease

There are of course many more, but the important thing for dental staff and patients to understand is what measures are taken within a dental surgery or practice to prevent cross infection from occurring.

The job of cross infection control concerns all dental staff, it is however mainly the responsibility of the dental nurse. The dental nurse must complete a number of hours of continuing professional development (CPD) about cross infection each year – this ensures that they are kept up to date with recent procedures and are also kept well informed of any new developments regarding cross infection control.

There are two types of cross infection;

  • Direct cross infection is the transfer of infection from one person to another
  • Indirect cross infection is the transfer of infection from one person to equipment to another person

Many harmful micro-organisms are passed on through blood or saliva, both of which are present in dentistry, and with the use of handpieces, water ,and ultrasonic instruments during dental treatment, blood and saliva can be spread around easily, rather than remain contained within the oral cavity. Instruments, the dentist and dental nurse will also come into close contact with blood and saliva during most dental procedures.

To prevent cross infection the harmful micro-organisms must be killed, this is most commonly achieved through sterilisation. Sterilisation results in asepsis – this can be defined as the absence of pathogenic micro-organisms. Specialist medical equipment known as an autoclave is used to achieve sterilisation. There are, however, some items within a surgery which cannot be sterilised such as the dental chair, operating lights, work surfaces and various plastic products, these items are either disposed of after use or are disinfected after use. Disinfection does destroy bacteria, fungi and some viruses; it does not destroy all viruses and cannot kill spores – which are an inactive type of bacteria.

All measures possible are to be followed by dental staff in order to control cross infection within the dental surgery.

About the author

I’ve been a dental nurse for over 13 years, and have worked in various parts of the country in orthodontic practices, general dental practices, within the community dental services, for both NHS and private practices. Within that time I’ve seen quite a few changes, not only with the way services are provided, changes in laws and regulations but also with the use of new materials and more advanced treatments. The one thing that hasn’t changed at all in my time as a dental nurse is the importance of people receiving and understanding clear information about dentistry, treatments, regulations and jobs for example.

One Comment

  1. gilbert Toronto cosmetic dentistry clinic garcia says:

    sometimes it happens when you get careless after having a dental procedure. it may be infect due to vulnerable of it when we are eating or get irritated by something.

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