The basic principles of infectious diseases as related to dental practice.

A variety of bacterial, viral, fungal, and protozoan microbes may present hazards to the dental team and to patients. After contamination with a microbe, three major factors determine if an infectious disease results: (1) virulence of the microbe, (2) the dose or number of microbial cells that contaminate the body, and (3) the resistance of the body to the microbe. Because nothing can be done about microbial virulence, prevention of infectious diseases involves decreasing the dose and increasing body resistance, coupled with education about disease spread and modes of prevention. The steps in the development of an infectious disease are (1) source of the microbe, (2) escape of the microbe from the source, (3) spread of the microbe to a new person, (4) entry of the microbe into the new person, and (5) infection and damage. The prevention of infectious disease can be accomplished by interfering with any of the above steps.