Glossary of Terms for Infection Prevention and Control in Dental Settings

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Administrative controls: the use of administrative measures (i.e., policies and procedures and enforcement measures) to reduce the risk of exposure to pathogenic organisms.

Aerosol: particles of respirable size (<10 µm) generated by both humans and environmental sources that can remain viable and airborne for extended periods in the indoor environment; commonly generated in dentistry during use of handpieces, ultrasonic scalers, and air/water syringes.

Airborne transmission: a means of spreading infection in which airborne droplet nuclei are inhaled by the susceptible host.
Air abrasion: the application of a mixture of small abrasive particles by air blast to prepare a cavity in a tooth or remove deposits from teeth.

Alcohol-based hand rub: an alcohol-containing preparation designed for application to the hands for reducing the number of viable microorganisms on the hands. In the United States, such preparations usually contain 60%–95% ethanol or isopropanol. These are waterless antiseptic agents not requiring the use of exogenous water. After applying such an agent, the hands are rubbed together until the agent has dried.

Allergen: an antigen, a substance capable of inducing allergy or specific hypersensitivity.

Allergic contact dermatitis: a type IV or delayed- hypersensitivity reaction resulting from contact with a chemical allergen (e.g., poison ivy, certain components of patient care gloves), generally localized to the contact area. Reactions occur slowly over 12-48 hours.

Anaphylaxis (immediate anaphylactic hypersensitivity): a severe and sometimes fatal Type 1 reaction in a susceptible person after a second exposure to a specific antigen (e.g., food, pollen, proteins in latex gloves, or penicillin) after previous sensitization. Anaphylaxis is characterized commonly by respiratory symptoms, itching, hives, and rarely by shock and death (anaphylactic shock).

Antibody: a protein found in the blood that is produced in response to foreign substances (e.g., bacteria or viruses) invading the body. Antibodies protect the body from disease by binding to these organisms and destroying them.

Antigen: a foreign substance, usually protein or carbohydrate substance (as a toxin or enzyme) capable of stimulating an immune response, usually the production of antibodies.

Antimicrobial soap: a soap (i.e., detergent) containing an antiseptic agent.

Antiseptic: a germicide that is used on skin or living tissue for the purpose of inhibiting or destroying microorganisms. Examples include alcohols, chlorhexidine, chlorine, hexachlorophene, iodine, chloroxylenol (PCMX), quaternary ammonium compounds, and triclosan.

Antiseptic handwash: washing hands with water and soap or detergents containing an antiseptic agent. Antiseptic hand rub. The process of applying an antiseptic hand-rub product to all surfaces of the hands to reduce the number of microorganisms present.

Asepsis: prevention from contamination with microorganisms. Includes sterile conditions on tissues, on materials, and in rooms, as obtained by excluding, removing, or killing organisms.


Bacterial count: a method of estimating the number of bacteria per unit sample. The term also refers to the estimated number of bacteria per unit sample, usually expressed as colony-forming units (CFUs) per square centimeter (cm2) per milliliter (ml).
Bacterial endocarditis: a bacterial induced inflammation of the lining of the heart and its valves.

Bead sterilizer (endodontic dry heat sterilizer): a device that used small glass beads (1.2–1.5 mm diameter) and high temperature (217–232oC) for brief exposures (e.g., 45 seconds) to inactivate microorganisms. The term is a misnomer because it is not cleared by the FDA as a sterilizer.

Bioburden: the microbiological load (i.e., number of viable organisms in or on the object or surface) or organic material on a surface or object prior to decontamination, or sterilization, also known as “bioload” or “microbial load.”

Biological indicator: a device to monitor the sterilization process that consists of a standardized population bacterial spores known to be resistant to the mode of sterilization being monitored. Biological indicators indicate that all the parameters necessary for sterilization were present.

Bloodborne pathogens: disease-producing microorganisms spread by contact with blood or other body fluids contaminated with blood from an infected person.

Bloodborne Pathogens Standard: a standard developed, promulgated, and enforced by the Occupational Safety and Health Administration (OSHA) directing employers to protect employees from occupational exposure to blood and other potentially infectious material.


Chemical indicator: a device to monitor the sterilization process that changes color or form with exposure to one or more of the physical conditions within the sterilizing chamber (e.g., temperature, steam). Chemical indicators are intended to detect potential sterilization failures that could result from incorrect packaging, incorrect loading of the sterilizer, or malfunctions of the sterilizer. A “pass” response does not verify that the items are sterile.

Chemical sterilant: chemicals used for the purpose of destroying all forms of microbial life including bacterial spores. 

Cleaning: the removal of visible soil, organic and inorganic contamination from a device or surface, using either the physical action of scrubbing with a surfactant or detergent and water or an energy-based process (e.g., ultrasonic cleaners) with appropriate chemical agents.

Colony-forming unit (CFU): the minimum number of separable cells on the surface of or in semi-solid agar medium which gives rise to a visible colony of progeny is on the order of tens of millions. CFUs may consist of pairs, chains, and clusters as well as single cells and are often expressed as colony-forming units per milliliter (CFU/ml).

Contaminated: state of having been in contact with microorganisms. As used in health care, it generally refers to microorganisms capable of producing disease or infection.

Control biological indicator: a biological indicator from the same lot as a test indicator that is left unexposed to the sterilization cycle and then incubated to verify the viability of the test indicator. The control indicator should yield positive results for bacterial growth.

Creutzfeldt-Jakob disease (CJD): a degenerative neurological disorder of humans thought to be transmitted by abnormal isoforms of neural proteins called prions. CJD is one of a group of related diseases known as transmissible spongiform encephalopathies (TSEs).

Critical: the category of medical devices or instruments that are introduced directly into the human body, either into or in contact with the bloodstream or normally sterile areas of the body (e.g., surgical scalpel) These items are so called because of the substantial risk of acquiring infection if the item is contaminated with microorganisms at the time of use.


Decontamination: a process or treatment that renders a medical device, instrument, or environmental surface safe to handle. According to OSHA, “the use of physical or chemical means to remove, inactivate, or destroy bloodborne pathogens on a surface or item to the point where they are no longer capable of transmitting infectious particles and the surface or item is rendered safe for handling, use, or disposal” [29 CFR 1910.1030].

Dental treatment water: nonsterile water used for dental therapeutic purposes, including irrigation of nonsurgical operative sites and cooling of high speed rotary and ultrasonic instruments.

Detergents: compounds that possess a cleaning action and have hydrophilic and lipophilic parts. Although products used for handwashing or antiseptic handwash in a health-care setting represent various types of detergents, the term “soap” is used to refer to such detergents in this guideline. Detergents make no antimicrobial claims on the label.

Direct Contact Transmission: physical transfer of microorganisms between a susceptible host and an infected or colonized person.

Disinfectant: a chemical agent used on inanimate objects (i.e., nonliving) (e.g., floors, walls, sinks) to destroy virtually all recognized pathogenic microorganisms, but not necessarily all microbial forms (e.g., bacterial endospores). The EPA groups disinfectants on whether the product label claims “limited,” “general” or “hospital” disinfectant.

Disinfection: the destruction of pathogenic and other kinds of microorganisms by physical or chemical means. Disinfection is less lethal than sterilization, because it destroys most recognized pathogenic microorganisms, but not necessarily all microbial forms, such as bacterial spores. Disinfection does not ensure the margin of safety associated with sterilization processes.

Distilled water: water heated to the boiling point, vaporized, cooled, condensed, and collected so that no impurities are reintroduced.

Droplet nuclei: particles 5µm diameter or less that are formed by dehydration of airborne droplets containing microorganisms that can remain suspended in the air for long periods of time.

Droplets: small particles of moisture (e.g., spatter) that may be generated when a person coughs or sneezes or when water is converted to a fine mist by an aerator or shower head. Intermediate in size between drops and droplet nuclei, these particles, although they may still contain infectious microorganisms, tend to quickly settle out from the air so that any risk of disease transmission is generally limited to persons in close proximity to the droplet source.

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Endotoxin: A part of the lipopolysaccharide, which can be found in the outer membrane of gram negative bacteria. Endotoxins often induce the immune response in a host, which can lead to the presentation of clinical signs and symptoms of infection.

Engineering Controls: controls (e.g., sharps disposal containers, self-sheathing needles, safer medical devices, such as sharps with engineered sharps injury protections and needleless systems) that isolate or remove the bloodborne pathogens hazard from the workplace.

Event-related packaging: a storage practice that recognizes that a package and its contents should remain sterile until some event causes the item(s) to become contaminated.

Exposure time: period of time during a sterilization or disinfection process in which items are exposed to the sterilant or disinfectant at the parameters specified by the manufacturer (e.g., time, concentration, temperature, pressure).


Germicide: an agent that destroys microorganisms, especially pathogenic organisms. Other terms with the suffix “–cide” (e.g., virucide, fungicide, bactericide, tuberculocide, sporicide) indicate an agent that destroys the microorganism identified by the prefix. Germicides may be used to inactivate microorganisms in or on living tissue (antiseptic) or on environmental surfaces (disinfectants).

Glycocalyx: a gelatinous polysaccharide and/or polypeptide outer covering. The glycocalyx can be identified by negative staining techniques. The glycocalyx is referred to as a capsule if it is firmly attached to the cell wall, or as a slime layer if loosely attached. This material produced by bacteria forms the structural matrix of biofilm.


Hand hygiene: a general term that applies to handwashing, antiseptic handwash, antiseptic hand rub, and surgical hand antisepsis.

Health-care-associated infection: any infection associated with a medical or surgical intervention. The term “health-care-associated” replaces “nosocomial,” which is limited to adverse infectious outcomes occurring in hospitals.

Hepatitis B Immune Globulin (HBIG): a product available for prophylaxis against hepatitis B virus infection. HBIG is prepared from plasma containing high titers of anti-HBs and provides short-term protection (3–6 months).

Hepatitis B surface antigen (HBsAg): a serologic marker on the surface of HBV. It can be detected in high levels in serum during acute or chronic hepatitis. The body normally produces antibodies to surface antigen as part of the normal immune response to infection.

Hepatitis B e antigen (HBeAg): a secreted product of the nucleocapsid gene of HBV and is found in serum during acute and chronic HBV infection. Its presence indicates that the virus is replicating and serves as a marker of increased infectivity.

Hepatitis B Surface Antibody (anti-HBs): the protective antibody against the surface antigen of the hepatitis B virus (HBsAg). Presence in the blood can indicate past infection with, and immunity to, hepatitis B virus, or an immune response from hepatitis B vaccine.

Heterotrophic bacteria: those bacteria that require an organic carbon source for growth (i.e., they derive energy and carbon from organic compounds). The modifier “mesophilic” describes bacteria that grow best within the middle ranges of environmental temperature.

High-level disinfection: a disinfection process that inactivates vegetative bacteria, mycobacteria, fungi, and viruses but not necessarily high numbers of bacterial spores. The FDA further defines a high-level disinfectant as a sterilant used under the same contact conditions except for a shorter contact time.

Hospital disinfectant: a germicide that is registered by EPA for use on inanimate objects in hospitals, clinics, dental offices, or any other medical-related facility. Efficacy is demonstrated against Salmonella choleraesuis, Staphylococcus aureus, and Pseudomonas aeruginosa.

Hypersensitivity: an immune reaction (allergy) in which the body has an exaggerated response to a specific antigen (e.g., food, pet dander, wasp venom). See allergic contact dermatitis, anaphylxis, latex allergy.


Iatrogenic: induced inadvertently by a HCW or by medical treatment or diagnostic procedures. Used especially in reference to an infectious disease or other complication of medical treatment.

Immunity: protection against a disease. Immunity is indicated by the presence of antibodies in the blood and can usually be determined with a laboratory test.

Immunization: the process by which a person becomes immune, or protected, against a disease. This term is often used interchangeably with vaccination or inoculation. However, the term “vaccination” is defined as the injection of a killed or weakened infectious organism in order to prevent the disease. Thus, vaccination, by inoculation with a vaccine, does not always result in immunity.

Implantable device: according to the Food and Drug Administration (FDA), “device that is placed into a surgically or naturally formed cavity of the human body if it is intended to remain there for a period of 30 days or more” [21 CFR 812.3(d)].

Independent water reservoir: a container used to hold water or other solutions and supply it to handpieces and air/water syringes attached to a dental unit. The independent reservoir, which isolates the unit from the public water system, may be provided as original equipment or as a retrofit device on all modern dental units.

Indirect Contact Transmission: contact of a susceptible host with a contaminated, intermediate object, usually inanimate.
Infectious microorganisms: microorganisms capable of producing infection in susceptible hosts.

Intermediate-level disinfection: a disinfection process that inactivates vegetative bacteria, most fungi, mycobacteria, and most viruses (particularly the enveloped viruses) but not bacterial spores.

Intermediate-level disinfectant: a liquid chemical germicide registered by the EPA as hospital disinfectant and with a label claim of potency as a tuberculocidal.

Irritant contact dermatitis: the development of dry, itchy, irritated areas on the skin, which can result from frequent handwashing and gloving as well as exposure to chemicals. This condition is not an allergic reaction.


Latex allergy: a type I or immediate anaphylactic hypersensitivity reaction to the proteins found in natural rubber latex.

Latex: a milky white fluid extracted from the rubber tree Hevea brasiliensis that contains the rubber material cis-1,4 polyisoprene.

Low-level disinfection: a process that will inactivate most vegetative bacteria, some fungi, and some viruses but cannot be relied on to inactivate resistant microorganisms (e.g., mycobacteria or bacterial spores).

Low-level disinfectant: a liquid chemical germicide registered by the EPA as a hospital disinfectant. OSHA requires low-level disinfectants also to have a label claim for potency against HIV and HBV if used for disinfecting clinical contact surfaces.


Mechanical indicator: devices (e.g., gauges, meter, display, printout) that display an element of the sterilization process (e.g., time, temperature, pressure).

Medical waste (Regulated): waste sufficiently capable of causing infection during handling and disposal (e.g., blood-or saliva-soaked cotton rolls, extracted teeth, sharp items, surgically-removed hard- and soft-tissues) to merit special handling and disposal.

Microfilter: membrane filter used to trap microorganisms suspended in water. Filters are usually installed on dental unit waterlines near the point of use as a retrofit device. Microfiltration commonly occurs at a filter pore size of 0.03 to 10 microns. Sediment filters commonly found in dental unit water regulators range from 20 to 90 microns pore size and do not function as microbiological filters.


N-95 respirator: one of nine types of disposable particulate respirators. “95” refers to the percentage of particles filtered. ( see “particulate respirator”).

Noncritical: the category of medical items or surfaces that carry the least risk of disease transmission. This category has been expanded to include not only noncritical medical devices but also environmental surfaces. Noncritical medical devices touch only unbroken (intact) skin (e.g., blood pressure cuff). Noncritical environmental surfaces can be further divided into clinical contact surfaces (e.g., light handle) and housekeeping surfaces (e.g., floors, countertops).

NIOSH: the National Institute for Occupational Safety and Health is the Federal agency responsible for conducting research and making recommendations for the prevention of work-related disease and injury. The Institute is part of the Centers for Disease Control and Prevention.

Nosocomial: describes an infection acquired in a hospital as a result of medical care (see definition for health-care-associated infection).

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Occupational exposure: a reasonably anticipated skin, eye, mucous membrane, or parenteral contact with blood or other potentially infectious materials that may result from the performance of an employee’s duties.

OPIM ( Other Potentially Infectious Materials): an OSHA term that refers to (1) The following human body fluids: semen, vaginal secretions, cerebrospinal fluid, synovial fluid, pleural fluid, pericardial fluid, peritoneal fluid, amniotic fluid, saliva in dental procedures, any body fluid that is visibly contaminated with blood, and all body fluids in situations where it is difficult or impossible to differentiate between body fluids; (2) Any unfixed tissue or organ (other than intact skin) from a human (living or dead); and (3) HIV-containing cell or tissue cultures, organ cultures, and HIV- or HBV-containing culture medium or other solutions; and blood, organs, or other tissues from experimental animals infected with HIV or HBV.

Opportunistic infection: an infection caused by a microorganism that does not ordinarily cause disease but is capable of doing so, under certain host conditions (e.g., impaired immune response).


Parenteral: means piercing mucous membranes or the skin barrier through such events as needlesticks, human bites, cuts, and abrasions.

Particulate respirator: also known as “air-purifying respirators” because they protect by filtering particles out of the air you breathe. Workers can wear any one of the particulate respirators for protection against diseases spread through the air- if they are NIOSH approved and if they have been properly fit-tested and maintained. NIOSH-approved disposable respirators are marked with the manufacturer’s name, the part number (P/N), the protection provided by the filter (e.g., N-95), and “NIOSH.” “95” refers to the percentage of particles filtered.

Percutaneous injury: an injury that penetrates the skin (e.g., needlestick, or cut with a sharp object).

Persistent activity: the prolonged or extended activity that prevents or inhibits the proliferation or survival of microorganisms after application of the product. This activity may be demonstrated by sampling a site several minutes or hours after application and demonstrating bacterial antimicrobial effectiveness when compared with a baseline level. In the past, this property was also called “residual activity.” Both substantive and non-substantive active ingredients can show a persistent antimicrobial effect if they lower the number of bacteria significantly during the handwashing period. Substantivity is an attribute of certain active ingredients that adhere to the stratum corneum (i.e., remain on the skin after rinsing or drying) to provide an inhibitory effect on the growth of bacteria remaining on the skin.

Personal protective equipment (PPE): is specialized clothing or equipment worn by an employee for protection against a hazard (e.g., gloves, masks, protective eyewear, gowns). General work clothes (e.g., uniforms, pants, shirts or blouses) not intended to function as protection against a hazard are not considered to be personal protective equipment.

Plain or non-antimicrobial soap: soaps or detergents that do not contain antimicrobial agents or contain very low concentrations of such agents that are effective solely as preservatives.

Planktonic: collective name free-floating microbiological organisms dispersed in solution, as in the case of free-swimming plankton.

Postexposure prophylaxis: the administration of medications following an occupational exposure in an attempt to prevent infection.

Potable (drinking) water: water suitable for drinking per applicable public health standards.

PPM (Parts per million): a measure of concentration in solution. For example, a 5.25% chlorine bleach solution (undiluted as supplied by the manufacturer) contains approximately 52,500 parts per million of free available chlorine.

Prevalence: the number of disease cases (new and existing) within a population at a given time.

Prion: a protein particle that lacks nucleic acid and has been implicated as the cause of various neurodegenerative diseases (as scrapie, Creutzfeldt-Jakob disease, and bovine spongiform encephalopathy). It is a pathogenic form of a neural protein that is both less soluble and more resistant to enzyme degradation than the normal form.


Qualified health-care professional: any licensed health care provider who can provide counseling and perform all medical evaluations and procedures in accordance with the most current recommendations of the US Department of Health and Human Services, including postexposure prophylaxis when indicated.


Regulated waste: liquid or semi-liquid blood or other potentially infectious materials; contaminated items that would release blood or other potentially infectious materials in a liquid or semi-liquid state if compressed; items that are caked with dried blood or other potentially infectious materials and are capable of releasing these materials during handling; contaminated sharps; and pathological and microbiological wastes containing blood or other potentially infectious materials.

Resident flora: species of microorganisms that are always present on or in the body and are not easily removed by mechanical friction.

Retraction: the entry of oral fluids and microorganisms into waterlines through negative water pressure.


Semicritical: the category of medical devices or instruments (e.g., mouth mirror) that come into contact with mucous membranes and do not ordinarily penetrate body surfaces.

Seroconversion: development of antibodies in the blood of an individual who previously did not have detectable antibodies.

Spatter: visible drops of liquid or body fluid that are expelled forcibly into the air and settle out quickly, as distinguished from particles of an aerosol, which remain airborne indefinitely.

Spaulding classification: a strategy for sterilization or disinfection of inanimate objects and surfaces based on the degree of risk involved in their use. The three categories are critical, semicritical, or noncritical. The system also established three levels of germicidal activity for disinfection (high, intermediate, and low).

Sterilant: a liquid chemical germicide that destroys all forms of microbiological life, including high numbers of resistant bacterial spores.

Sterile/sterility: state of being free from all living microorganisms. In practice, usually described as a probability function, (e.g., the probability of a surviving microorganism being 1 in 1,000,000).

Sterile water: water that is sterilized and contains no antimicrobial agents.

Sterilization: the use of a physical or chemical procedure to destroy all microorganisms including large numbers of resistant bacterial spores.

Surfactants: surface-active agents that reduce surface tension. They help cleaning by loosening, emulsifying, and holding soil in suspension, which can then be more readily rinsed away.

Surgical hand scrub: an antiseptic-containing preparation that substantially reduces the number of microorganisms on intact skin; it is broad-spectrum, fast-acting, and persistent.


Transient flora: microorganisms that may be present in or on the body under certain conditions and for certain lengths of time; they are easier to remove by mechanical friction than resident flora.

Transmissible spongiform encephalopathies (TSEs): a group of rapidly progressive, invariably fatal, degenerative neurological disorders affecting both humans and animals that are caused by infection with prions (see Creutzfeldt-Jakob disease and prion).

Transmission-based precautions: a set of practices that apply to patients with documented or suspected infection or colonization with highly transmissible or epidemiologically important pathogens for which precautions beyond the standard precautions are needed to interrupt transmission in health-care settings.

Tuberculosis infection, latent: a condition in which living tubercle bacilli (M. tuberculosis) are present in the body but the disease is not clinically active. Infected persons usually have positive tuberculin skin test, but they have no symptoms related to the infection and are not infectious. Infected persons remain at lifelong risk for developing disease, however, if they are not given preventive therapy.

Turbidity: cloudiness.


Ultrasonic cleaner: a device that uses waves of acoustic energy (a process known as “cavitation”) to loosen and break up debris on instruments.


Vaccination: see immunization.

Vaccine: a product that produces immunity therefore protecting the body from the disease. Vaccines are administered through needle injections, by mouth and by aerosol.

Ventilation: the process of supplying and removing air by natural or mechanical means to and from any space; such air may be conditioned.


Washer-disinfector: an automatic unit designed to clean and thermally disinfect instruments. The unit uses a high-temperature cycle rather than a chemical bath.

Wicking: absorption of a liquid by capillary action along a thread or through the material (e.g., the enhanced penetration of liquids through undetected holes in a glove).

Work practice controls: are practices incorporated into the everyday work routine that reduce the likelihood of exposure by altering the manner in which a task is performed (e.g., prohibiting recapping of needles by a two-handed technique).

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