The aim of this chapter is to describe the risks of contracting an infectious disease in the dental surgery environment.
After reading this chapter, you should have a basic understanding of how infectious disease could potentially be transmitted in dentistry.
Infection control in dentistry is all the methods we use to prevent the transmission of potentially pathogenic micro-organisms. The transmission of micro-organisms does not always result in infection. To cause an infection, the micro-organisms have to be transferred in sufficient numbers and then multiply to cause infectious disease. The number of bacteria, viruses, fungi or prions that are necessary to infect is called the minimum infective dose, as can be measured in experimental animals. The minimum infective dose can be decreased if a person’s defence mechanisms are impaired, for example, by chronic longstanding debilitating disease, medical interventions (immunosuppressive drugs, cytotoxic therapy) or very rarely by congenital disease; such patients are described as being medically compromised or immunocompromised.
When dentistry was practised without the use of any protective barriers or effective decontamination, there was an increased potential for the transmission of infection by direct contact. The routine use of barrier methods has reduced this potential to almost nil. With the growth in world travel and the increase in hepatitis, HIV and tuberculosis, infection control in dentistry is all the more important.
Dental procedures often create aerosols containing water, blood and saliva.
The risk from the inhalation of aerosols by patients or dental personnel has never been completely or reliably assessed. The highest risk of transmission of infection is by direct blood-to-blood contact. This contact can occur through injuries by “sharps” that penetrate the epithelium or by direct inoculation of wounds by contaminated instruments. Another potential route of transmission is through the conjunctiva of the eye.
Although potentially any micro-organism could cause infection in dentistry, in practice only a selected few have been proven to be involved. These are shown in Table 1-1. This is because the oral cavity and saliva are selective in the number and type of micro-organisms that are usually present. In addition, while blood could contain many pathogens, it is usually sterile. Nevertheless, it is wise to routinely presume that every patient is potentially infectious. The presumption that every patient is potentially infectious logically leads to use of a standard set of infection control methods; these are often called universal or standard precautions. The use of standard precautions for every patient has not been adopted by all dentists. In some countries different types of infection control precautions are used for different procedures; this is problematical as it presumes that patients can be accurately assessed as potential carriers of disease but this is often not possible.
|Micro-organism||Probable route of transmission|
|Herpes simplex type 1||
Hands, record cards, splatter from oral cavity