The risk of infectious disease transmission is an inherent part of dental practice. Fortunately, such risks can be greatly reduced through modern infection control practices. Such practices include the use of various measures, including administrative, engineering, and work practice controls. Such measures should be codified in an office infection control plan, which should form the basis for the daily infection control activities of the staff. This article discusses some of the measures that should be taken to safeguard the health of dental healthcare workers and patients.
Dental health care personnel (DHCP) work in close proximity to their patients. DHCP perform procedures which may induce their patients to cough. Their field of surgery is awash in saliva, which is usually contaminated with blood. Many dental procedures produce aerosolized droplet nuclei, which may linger in the atmosphere for hours. Obviously, the risk of disease transmission is an inherent part of dental practice. The good news is that dental care can be provided with a high degree of safety for the patient and therapist, provided that the tenets of modern infection control are adhered to. One of the most comprehensive sources of information regarding infection control practices in the dental setting is available from the Centers for Disease Control and Prevention .
The office safety and infection control (SIC) program provides a framework in which dental treatment can be rendered safely and effectively. The ultimate legal responsibility for implementing such a program resides with the owner of the practice, but the plan requires the full cooperation of the entire staff.
An infection control (IC) plan–that is part of a larger safety plan–has as its goal the protection of patients and health care workers. The plan must provide for:
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creation of IC protocols designed to safeguard the health and safety of both patients and staff;
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ongoing training;
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surveillance of infection control hazards and exposures;
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ongoing quality assurance and continuous improvement;
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regulatory compliance.
It may be helpful to designate a staff member as the SIC officer who is responsible for plan implementation, staff training, and quality assurance.
Standard precautions
Transmission of bloodborne pathogens can normally be prevented through the use of standard precautions. The Centers for Disease Control (CDC) defines standard precautions as “any standard of care designed to protect health care personnel and patients from pathogens that can be spread by blood or any other bodily fluid, excretion, or secretion.” The term “standard precautions” replaces the term “universal precautions.” Standard precautions apply to contact with blood, bodily fluids (except sweat), intact mucous membranes, and non-intact skin. These precautions are normally sufficient to prevent the transmission of infectious agents in the dental setting.
Records maintenance and security
Employers must create and maintain confidential health records for all employees. Such information must be maintained in secure files for the duration of employment plus 30 years . These records must contain immunization records, occupational exposures to bloodborne pathogens (BBP), injuries, and medical work restrictions. It is also necessary to keep records of training, including information like dates, presenters, and topics. Training records should be kept for at least 3 years .
Records maintenance and security
Employers must create and maintain confidential health records for all employees. Such information must be maintained in secure files for the duration of employment plus 30 years . These records must contain immunization records, occupational exposures to bloodborne pathogens (BBP), injuries, and medical work restrictions. It is also necessary to keep records of training, including information like dates, presenters, and topics. Training records should be kept for at least 3 years .
Infection control training
Who must be trained?
Mandatory infection control training is needed by any staff members who are at risk of exposure to bloodborne pathogens. This would include all clinical staff, including laboratory technicians, but may also include administrative personnel who have contact with patients and handle charts (which may be contaminated). For each individual practice, practice owners are legally obligated to assess the potential risk inherent in each position and train staff accordingly. Staff members who are to be included in such training will hereafter be referred to as “clinical staff” regardless of the exact nature of their duties.
Volunteers and observers
It is not uncommon for volunteers and observers to be present in the clinical environment. While this is more common in institutions such as dental schools, it is also common in dental practices, especially those in which dental or hygiene students must rotate. At our institution, such individuals receive abbreviated training in the Health Insurance Portability and Accountability Act of 1996 (HIPAA) and IC. Such individuals may be injured during their observational experience. If such individuals are present in the practice, an appropriate policy should be developed regarding mandatory training, hepatitis B immunization, and postexposure protocol should an injury occur. Appropriate legal counsel should be sought in developing these guidelines.
When should such training be taken?
All clinical staff must receive mandatory training in safety and infection control. All training must be documented in an employee training record. Training must be received at the time of initial assignment, or whenever there are changes in procedure or clinical responsibilities. Training should be conducted annually thereafter. Training sessions should be held during working hours. It may be convenient to review IC issues at monthly staff meetings on an ongoing basis. If this is done, a formal record of the training should be kept for all attendees.
What topics must be covered?
At a minimum, training should cover: the Occupational Safety and Health Administration (OSHA) Standard; bloodborne diseases (especially hepatitis B [including information on immunization], hepatitis C, and HIV/AIDS); the office-specific exposure control plan; the use and care of personal protective equipment (PPE); postexposure protocol; and hazard communication (eg, biohazard symbols).
Resources
Many videos and instructional materials are available for training. However, the training must be specific and appropriate to the individual office. Also, employees must be given the opportunity to ask questions. The written IC plan must also be specific to the individual office. It is acceptable, however, to use a generic IC video if it is followed by an office-specific training session. Following the initial training session(s), there should be an annual IC update.
General information on infection control is available from a number of sources. Chief among these are the latest guidelines from the Centers for Disease Control and Prevention (ie, Guidelines for Infection Control in Dental Healthcare Settings – 2003 ) . Information is also available from OSHA ( www.osha.gov ), the National Institute for Occupational Health (NIOSH; www.cdc.gov/niosh/ ), the American Dental Association (ADA; http://www.ada.org/ ), the Organization for Safety and Asepsis Procedures (OSAP; http://www.osap.org/ ), and the Association for Professionals in Infection Control and Epidemiology (APIC; http://www.apic.org ). The Regulatory Compliance Manual is available from the ADA and is a good source of general information .
Nature of the threat
Theoretically, almost any infectious disease could be transmitted in the dental setting, but there are a few diseases that are of special importance. These significant diseases include hepatitis B, hepatitis C, HIV, and tuberculosis. An exposure is said to exist when an individual has possibly come in contact with such pathogens. An accidental needlestick is an example of a percutaneous exposure. Other exposures can occur when a piece of calculus lands in an assistant’s eye or when airborne infections are spread by aerosols generated by a dental handpiece or by a patient’s sneeze or cough.
Standard precautions are effective in breaking the chain of infection, since transmission of the hepatitis B virus is rare in cases where proper IC protocols are followed. Even when an exposure occurs, infection is not inevitable. The risk of infection following exposure is determined by a number of factors, including inoculum size (ie, how big a dose of organisms the person is exposed to), the method of exposure (material splashed in the eye versus needlestick), and the susceptibility of the host.
Inoculum size is an important concern in determining the risk of infection. Hollow needles, which can carry a larger number of pathogens due to the hollow channel or lumen within the needle, are much more effective in transmitting infection than solid instruments such as suture needles. The rate of infection following needlestick is also dependent upon the pathogen. For example, the rate of infection following a needlestick (ie, percutaneous) injury is greater for cases of hepatitis B virus (6%–30%) than for hepatitis C virus (0%–7%) or HIV (0.3%) .
Viral hepatitis
Hepatitis is a generic term that means inflammation of the liver. Hepatitis can be caused by viral and bacterial infections, by other parasites, or by exposure to chemicals and drugs (such as alcohol). Viral hepatitis is caused by any of a number of viruses . Three types of viral hepatitis are especially important in the dental setting.
Hepatitis B
Hepatitis B is caused by the hepatitis B virus (HBV) . Hepatitis B is the bloodborne pathogen most likely to be encountered in the dental workplace. HBV is also persistent. The viral particles may remain infectious for a week in dried blood at room temperature. In dentistry, the most common route of transmission from patient to DHCP is from a percutaneous exposure via needlestick or a similar event. For this reason, it is the target organism for infection control measures. If IC measures are effective in preventing the transmission of hepatitis B, they will probably be effective in preventing the transmission of most other bloodborne diseases.
There are an estimated 200 to 300 million carriers of HBV worldwide, with over 1 million Americans chronically infected. Certain high-risk populations have been identified, such as health care workers, intravenous drug users, female prostitutes, male homosexuals, and immigrants from certain regions having a high prevalence of HBV (eg, Asia, Africa, the Middle East, Haiti). However, it is important to note that anyone can be a carrier of HBV. Approximately 10% of those with primary HBV infection eventually become carriers. Although several markers (antigens) are characteristic of HBV, the one most often used to determine infectivity in asymptomatic carriers is the hepatitis B surface antigen. HBV carriers are at greatly increased risk for hepatocellular carcinoma, cirrhosis, and transmission to family members.
The symptoms of the initial HBV infection are often mild, and the infected individual may mistake them for influenza. Most individuals with HBV do not experience jaundice during the initial infection. HBV causes over 4000 deaths per year in the United States. Fortunately, the incidence of HBV is declining due to the combined effects of improved IC practices, better education, and the availability of an effective vaccine.
The availability and wide use of the HBV vaccine has greatly reduced the number of infected health care workers; it is a public health success story. All health care workers should be vaccinated against hepatitis B. Currently available forms of the vaccine are 98%–99% effective. Three injections are required in the series. All DHCP should be immunized against HBV within 10 days of their first contact with patients. Individuals may see patients during the period (normally 2–6 months) that it takes to complete the immunization series. Any DHCP who do not wish to be immunized must sign a form of declination that should be kept in the employee’s file. An example of such a letter is found in the appendix. Employers are responsible for offering this immunization to their patients free of charge. Upon hiring new clinical DHCP, an employer may wish to see evidence of immunization although this is not mandated by OSHA.
Hepatitis C
Hepatitis C virus (HCV) is the most common cause of so-called “non-A, non-B hepatitis .” Eighty percent of HCV infections result in a chronic carrier state, which contributes to the importance of this agent. It is estimated that there are almost 4 million infected persons in the United States, including over 2 million infectious carriers. Risk factors for HCV include exposure to blood and body fluids (eg, needlesticks, sharing needles) and multiple sex partners. In many cases, no risk factor can be identified. No effective vaccine exists for hepatitis C.
Hepatitis D
Hepatitis D is unique because the virus can only replicate in the presence of the hepatitis B virus . Patients infected with both HBV and the hepatitis D virus (HDV) sometimes have a particularly severe form of hepatitis known as fulminant hepatitis. Because HDV requires coinfection with HBV, it is likely that vaccination against HBV will also provide protection against HDV.
HIV
In 1981, the CDC published the first reports of unusual opportunistic infections in homosexual men in Los Angeles . These men were diagnosed with Pneumocystis carinii pneumonia (PCP), an infection not usually seen in healthy young adults. This brief report signaled the beginning of the AIDS epidemic, a public health event that transformed health care and focused increased attention on infection control.
Although the AIDS epidemic focused increased attention on IC in the dental setting, the danger of transmission in this setting is apparently low. According to the CDC, as of December 2001 there were no reports of transmission of HIV to DHCP as a result of workplace exposures. There is one report of HIV transmission from a dentist to several patients, but the mode of transmission has never been ascertained and this appears to be a highly unusual, isolated case.
In an effort to quantify the risk of transmission from health care worker to patient, the CDC examined over 22,000 patients who were treated by 63 HIV-infected health care providers (including 33 dentists or dental students) and found no additional cases of transmission. It would appear that the risk of transmission in the dental workplace is quite low.
Routes of HIV transmission include contact with contaminated blood, other body fluids, or other potentially infectious material (OPIM). Transmission can occur via sexual contact, needle sharing, and vertical transmission from mother to child. HIV-positive individuals may remain asymptomatic for years. Eventually, however, the immune system fails and the person develops AIDS. The virus is shed in blood and saliva, and low viral levels have been found in oral secretions. There is no cure for AIDS, although new drug regimens, such as highly active antiretroviral therapy, have proven much more effective than older protocols. The new protocols have resulted in greatly increased longevity for AIDS patients.
Tuberculosis
Tuberculosis (TB) is caused by the tubercle bacillus, Mycobacterium tuberculosis (Mtb) . TB is spread chiefly through extremely small airborne droplet nuclei produced when an infected individual sneezes, coughs, or speaks. These droplet nuclei can remain airborne for hours. However, contact with Mtb is not sufficient to cause active tuberculosis. Many individuals have been exposed to the organism and have developed a latent infection (as indicated by a positive TB skin test), but only about 10% of these individuals will develop active TB during their lifetime. (This proportion is greatly increased in persons infected with HIV.) In many cases, the organism remains in a latent or hidden state. In some cases, these latent tuberculosis infections (LTBI) may be reactivated when immune function deteriorates (eg, due to AIDS or increasing age). TB is the most common cause of death from infectious disease in the world, particularly in parts of the former Soviet Union, Asia and Mexico. Of great concern in these areas is the emergence of multidrug-resistant TB.
Prion diseases
Prion diseases are unique . Prions are not bacteria and they are not viruses. In fact, they are infectious proteins that lack a genome. It is difficult to imagine prions as living organisms in the generally accepted sense of that term. The best-known example is the so-called “mad cow disease” (also known as bovine spongiform encephalopathy or BSE). Mad cow disease is an example of a group a diseases known as transmissible spongiform encephalopathies or TSEs. Initially, it was recognized that mad cow disease was similar to a human condition known as Creutzfeldt-Jakob disease. It appears that consumption of meat tainted with the BSE agent may result in human infection known as variant CJD.
Normal methods of sterilization may not be effective in killing or inactivating prions. These diseases have exceptionally long incubation periods (10–30 years) which greatly complicate the epidemiologic study of the mode of transmission. Some materials used in periodontal and oral surgery use materials are derived from cattle (ie, certain collagen membranes, sutures, xenograft bone graft materials), although there have been no reported instances of contamination from these materials.
Other infections
When discussing disease transmission in the dental setting, the focus is naturally upon those infections with the most serious consequences such as AIDS and HBV. However, more common diseases such as the common cold, influenza, various herpes viruses, and STDs may also be transmitted. Some, such as influenza, may have serious sequelae. The safeguards taken to prevent transmission of HBV, for example, will also reduce the chances for transmission of other, more common pathogens. While usually not life-threatening, diseases such as the common cold and herpetic skin infections may be debilitating and unpleasant for dental health care workers and their families.
Breaking the chain of infection
Infectious diseases spread by direct contact between individuals, via airborne droplets, or by contact with fomites such as contaminated surfaces or instruments. One of the most important routes of transmission in the dental workplace is direct exposure to blood and body fluids (BBF), as well as other potentially infectious material (PIM). Blood is the most important fluid. Blood is usually found in saliva, due to gingival bleeding. Therefore, all saliva is considered a potentially infectious material and must be treated with caution.
A number of strategies are available to reduce the possibility of cross-infection. These include training, workplace restrictions, immunization, the use of personal protective equipment, and safe work practices, including the use of safer instruments, such as retractable needles. All of these elements, plus quality assurance mechanisms, should be included in the infection control plan.
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