Infection Control for Dental Assisting Exam Study Guide

Updated on Jun 23, 2011

Practice problems for this study guide can be found at:

Infection Control for Dental Assisting Exam Practice Problems

Each dental professional has a responsibility to be aware of current infection control techniques and trends. Infection control is an area of dentistry that is constantly altering and evolving. Rules and regulations change yearly, and some states are more stringent than others. Infection control updates should be a regular part of a dental professional’s continuing education. In fact, this is an Occupational Safety and Health Administration (OHSA) requirement.

Concepts and Skills

Infection control is broken down into four main areas:

  • Disease Transmission
  • Occupational Safety and Health Administration (OSHA)/Centers for Disease Control and Prevention (CDC)
  • Disinfection
  • Sterilization

The following outline chronicles current information regarding each area of infection control.

Disease Transmission

Germs are the main causes of disease. Germs are also termed microorganisms and/or pathogens. When these germs multiply, they become diseases. Diseases can be transmitted only in a distinct pathway. This pathway is known as the chain of infection.

Chain of Infection

The chain of infection contains four links: virulence, number of microorganisms, susceptible host, and portal of entry. All of these must be present for the individual to become infected with a disease. If one of these is missing, the disease cannot be transmitted.


The virulence of an organism is its strength or ability to cause disease. The more virulent the organism, the more serious the disease. A virulent disease is also more difficult for the body to fight off and could be resistant to certain medications.

Number of Microorganisms

The number of microorganisms describes the amount of pathogens present. A large number of pathogens will overwhelm the body’s immune system and diminish the body’s ability to fight off the pathogens.

Susceptible Host

A susceptible host is someone who has a compromised immune system. This means that this person has a disease already, is currently undergoing treatment for a condition, has not been getting enough rest, and is run down or under stress. These things can suppress a person’s immune system and cause her or him to be more susceptible to an illness or disease.

Portal of Entry

A portal of entry is the way in which an infection enters the body. An infection can enter the body through various modes.

Modes of Disease Transmission

An infectious disease is one that is contagious and can be transmitted from host to host via the chain of infection. Diseases are transmitted in one of the following five modes of transmission: direct; indirect; airborne; aerosol, spray, or spatter; or blood-borne transmission.

Direct Transmission

This route of transmission occurs when there is direct contact with infected blood, saliva, or other potentially infectious materials (OPIM). Personal protective equipment (PPE) is essential in preventing transmission.

Indirect Transmission

This route of transmission occurs when the dental healthcare professional comes in contact with a contaminated surface without the protection of PPE.

Airborne Transmission

This route of transmission occurs through methods of inhalation. For example, a patient sneezes, and another inhales some spores that may be present in the sneeze. Many serious diseases are spread via the air.

Aerosol, Spray, or Spatter

This route of transmission is a form of airborne transmission. Aerosol is generated by the use of the high-speed hand piece in the mouth. An aerosol mist is emitted from the oral cavity, which is contaminated with the patient’s bacteria. Spray and spatter follow the same form, but are larger in size than an aerosol mist. These occur in the patient’s mouth and splash out of the oral cavity, contaminating the surrounding area.

Blood-Borne Transmission

This route of transmission occurs only from blood-to-blood contact with an infected individual. Many diseases, such as HIV/AIDS and Hepatitis C, are transmitted this way. The most common method of transmission is through a needle-stick injury. Therefore, maintaining safe practices and procedures while paying attention to details helps prevent this type of transmission.

Disease Transmission in the Dental Office

All members of the dental healthcare team should be concerned about disease transmission in the dental office. Dental professionals call this cross-contamination. Cross-contamination refers to germs within or from the dental setting being transmitted to other areas of the dental office or carried out of the dental setting. This can occur in a number of ways, including patient to patient, healthcare worker to patient, patient to healthcare worker, and healthcare worker to community.

Patient to Patient

Cross-contamination can occur from patient to patient by not changing PPE between patients, by not properly disinfecting the treatment room, and by not properly sterilizing the dental instruments. The germs and bacteria are then introduced into a new host, causing a “sharing” or “crossing” of infection. It is imperative that dental assistants understand the importance of preventing cross-contamination.

Healthcare Worker to Patient

The patient and dental healthcare worker sit in very close proximity to one another. Therefore, it is possible for the dental healthcare worker to transmit microorganisms to the patient unintentionally. It is important to don fresh PPE for each patient. This includes a new pair of disposable gloves; a new disposable mask; and clean, disinfected safety glasses. Hand washing is always an important aspect of infection control.

Patient to Healthcare Worker

The patient can also transmit microorganisms to the dental healthcare team. The same precautions as above should be followed by the dental healthcare team to prevent the transmission of microorganisms.

Healthcare Worker to Community

The dental healthcare worker may unintentionally transmit contaminants from the dental setting into the community. Care should be taken by the dental healthcare worker to avoid this by changing into street clothes prior to leaving the office, and laundering contaminated clothes properly.

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