The chain of infection and how to break it: Dental assisting

The chain of infection is a six-link chain that represents conditions that must be present for an infection to develop, and a break anywhere in the chain can stop it. In the dental setting, there’s a high risk of infection due to the types of procedures performed and the close contact the dental team has with patients. As a dental assistant, you play an important role in implementing infection control strategies to break the chain of infection.

Now, the six links in the chain of infection are an infectious agent, a reservoir, a portal of exit, a mode of transmission, a portal of entry, and a susceptible host.

Infectious agents include pathogens, which are microorganisms that can cause disease. The pathogens commonly found in the dental office are bacteria, viruses, and fungi. For a pathogen to cause an infection, it needs to be present in sufficient numbers, and it must have a high degree of virulence, which is the severity of disease the microorganism can cause.

The place where microorganisms typically live and reproduce is called a reservoir. The main reservoirs in the dental office are organic materials, such as blood and saliva. In fact, universal precaution guidelines are based on the principle that all blood and body fluids should be considered potentially infectious.

Other reservoirs can include contaminated surfaces such as hands, dental instruments, frequently touched items like computer keyboards, tables, trays, sinks, and the dental chair.

Now, to be infectious, microorganisms need to have a portal of exit, or a way to leave its reservoir. In the dental office, pathogens most often exit through the mouth, nose, and blood.

After the pathogen exits their reservoir, it needs to spread through a mode of transmission, like through the air or through contact with a person or contaminated object.

Next, the way microorganisms enter a person’s body is through a portal of entry. These include inhaling them through the nose and mouth, and through contact with the mucous membranes of the eyes, nose, and mouth, and contact with breaks in the skin like cuts, scrapes, and needle sticks.

The final link is a susceptible host, or the person at risk of infection. Factors that increase susceptibility include a weakened immune system; chronic illnesses like diabetes or cancer; being very young or very old; and other factors like stress, fatigue, malnutrition, or not being immunized.

Transmission of pathogens can occur in the dental setting in multiple ways, and can affect all individuals, including patients, visitors, and the dental team.