Chapter 12 Infection control
Infection control
There are problems in categorizing which level of infection control is appropriate for dentistry. Many of the patients who attend dental surgeries may asymptomatically carry potentially infectious diseases but they do not know they are infected (e.g. hepatitis B or C). The risk of transmission could be high in dentistry if there is blood to blood contact through, for example, an inoculation (sharps) injury. In addition, the major fluids encountered in dentistry are blood and saliva and these could potentially transmit infectious disease. The risk for most of the surgical procedures done in dentistry, therefore, is in the medium category. Since most dental patients who asymptomatically carry disease are unaware of their infectious status it is wise to treat everyone with the same precautions; these are often described as Standard or Universal Precautions.
Which infectious diseases are transmitted by dentistry?
The number of proven cases of infectious diseases that have been transmitted by dental personnel, treatment or patients is very limited and the diseases are listed in Table 12.1. The pathogens include Mycobacterium tuberculosis (the causative organism of the majority of cases of tuberculosis in humans), methicillin resistant Staphylococcus aureus (MRSA), Pseudomonas spp., and the hand, foot and mouth virus (Ch. 10), and their transmission has resulted in serious, but not life-threatening infections. The list also includes infections caused by Legionella spp. and hepatitis B virus which have resulted in death of dental personnel. The most infectious agent that is constantly present in the oral cavity of at least 30% of the population is herpes simplex type 1 (Ch. 10). This virus has not caused death, but it has been responsible for blindness, usually in dental personnel who do not wear protective spectacles. Some authors have reviewed the low number of transmissions of infection in dentistry and have questioned whether many of the precautions used are necessary or justified, based on a risk assessment. Whether infection control measures in dentistry are necessary cannot now be answered as it would be impossible to revert to anything but standard precautions. Public pressure and ethical responsibility would prevent any diminution in the standard of precautions or to test a reduced level of protection. In addition, most regulatory authorities now demand standard precautions are taken in dentistry and have used litigation to ensure that it is done.
Table 12.1 Proven cases of infection transmitted by dentistry.
| Infectious agent | Route of infection |
|---|---|
| HIV | Use of infected instruments or direct injection of blood |
| Hepatitis B virus | Sharps injury |
| Herpes simplex type 1 virus | Contact of infected material with skin or eyes |
| Coxsackie viruses | Contact with skin |
| Legionella spp | Inhalation of contaminated dental unit water supplies |
| Pseudomonads (e.g. Pseudomonas aeruginosa) | Contact with contaminated dental unit water supplies |
| MRSA (Methicillin resistant Staphylococcus aureus) | Contact with skin |
| Mycobacterium tuberculosis | Inhalation of infected droplets |
Personal protection
Immunization
The protection of dental personnel by immunization before they engage in dental procedures is an important part of infection control. Nowadays, many regulatory authorities require that dentists, nurses, hygienists and therapists are not carrying any potentially infectious disease before they undertake or assist with any dental procedures. Freedom from infectious disease and satisfactory records of immunization should be a contractual prerequisite before dental personnel are employed. The vaccinations required are listed in Table 12.2 and many of these are done routinely in adolescence. The exception to this is hepatitis B vaccination which needs to be satisfactorily completed before any exposure to surgical procedures is done.
Table 12.2 Recommended vaccinations for all dental personnel.
| Vaccine | Route | Length of protection |
|---|---|---|
| Diphtheria | IM* | Probably life-long |
| Hepatitis B | IM | At least 5 years but probably life-long |
| Pertussis (Whooping Cough) | IM | Probably life-long |
| Poliomyelitis | IM | Probably life-long |
| Rubella | IM | Probably life-long |
| Tetanus | IM | At least 10 years but probably life-long |
| Tuberculosis (BCG) | IM | Probably less than life-long in most recipients |
Hand protection
Hands of dental personnel are potentially one of the most vulnerable areas of the body to infectious disease and also may be a potential vector for infection. The maintenance of an intact layer of epithelium, although difficult to achieve, is an important part of protection. The problem is that procedures such as handwashing in soap and water, and covering hands with gloves, can have a serious and deleterious effect on the integrity and pliability of the skin. Both glove wearing and handwashing can have a hyperosmotic effect on the hands and cause the skin to crack and lose its pliability, thereby rendering it susceptible to microbial ingression. Handcreams used after every session restore essential oils to the skin and help retain pliability.
Handwashing has to be done systematically ensuring that all surfaces are washed and rinsed. The technique devised by Ayliffe (Fig. 12.1) ensures that all surfaces are washed and rinsed. If the hands are not visibly contaminated after patient treatment then the use of combined alcohol and disinfectant handrub/>
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