DENTAL INFECTION CONTROL AT THE YEAR 2000

C O V E R S T O R Y

DENTAL INFECTION CONTROL AT THE YEAR 2000 ACCOMPLISHMENT RECOGNIZED JOHN A. MOLINARI, PH.D.

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s the last months of the 20th century approach, the health professions are presented with a unique opportunity to assess the evolution of their infection control practices. Many dental practitioners already have done this, often without realizing it. For example, most dentists, hygienists and assistants who were educated more than 20 years ago readily attest that they adopted, and adapted to, numerous infection control practices after they had practiced a certain way for years. The routine application of precautions such as multiple aseptic procedures, latex gloves, masks, protective eyewear, clinic coats, automated instrument decontamination devices, time-efficient heat sterilization modalities, chemical disinfectants, waste management procedures and single-use disposable items have created a safer environment for dental personnel and patients alike. Evidence supporting the application of these and other current practices includes a long history of scientific and clinical investigations, technological advances in equipment and materials, and periodic publication of updated recommendations by professional health care organizations. As a consequence, students are now taught principles of appropriate infection control at the beginning of the curriculum, and they apply them from their earliest preclinical and clinical experiences. An often-overlooked aspect of the current status of education, however, is that many dental health care workers did not have the benefit of formalized infection control training while in school and, therefore, had to struggle to adapt to the practice while treating patients.

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Overview. Health care providers have strived to address the many elements necessary to achieve effective infection control. Historical progress in microbiology and hospital asepsis provided the foundation for advances in dental preventive practices. Evidence supporting the application of current practices includes a long history of scientific and clinical investigations, technological advances in equipment and materials, and periodic publication of updated recommendations by professional health care organizations. Clinical Implications. The routine application of precautions such as multiple aseptic procedures, latex gloves, masks, protective eyewear, clinic coats, automated instrument decontamination devices, time-efficient heat sterilization modalities, chemical disinfectants, waste management procedures and single-use disposable items have created a safer environment for dental personnel and patients alike.

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SOME 20TH-CENTURY ACCOMPLISHMENTS IN INFECTION CONTROL. dRecognition of relationship between microbial pathogens and risk of occupational transmission of infectious disease: bloodborne, airborne, wound, acute, chronic dDevelopment and refinement of efficient aseptic techniques: hand-washing procedures, classes of antiseptics, infection control cleaning procedures dConversion from chemical immersion to heat sterilization procedures for instrument reprocessing dAdaptation to use of personal protective barriers during patient care: gloves, face masks, eyewear, clinic coats and gowns dReceipt of hepatitis B vaccine and other vaccines recommended for health professionals dApplication of universal precautions against bloodborne disease as infection control standard for patient treatment dAdaptation of safer procedures to minimize accidental exposures to contaminated sharp items dDevelopment and use of newer technologies to prevent microbial cross-contamination and facilitate better infection control: sterilizers; personal and equipment barriers; automated instrument cleaning equipment; reusable, heat-stable dental instrumentation; single-use disposable needles; technical advancements in promoting dental unit water asepsis dProvision of routine care to patients with increasing variety of immune system compromise dDiscovery and development of antimicrobial antibiotics to treat clinical infections

These people deserve credit for serving as infection control pioneers and role models for the graduates who came after them. A few practitioners occasionally voice concerns about the possibility of being subjected to an inspection by the Occupational Safety and Health Administration, or OSHA. And there is little doubt that the 1991 publication of the OSHA Bloodborne Pathogens Standard1 had a pronounced effect on the way infection control is practiced in all medical and dental care settings. Even with the OSHA consideration present, however, it has been my experience that the over1292

whelming majority of dental care providers feel comfortable with the recommended precautions and practice accordingly. In light of this success, one could become overly optimistic and suggest that all of the major issues have been addressed.

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nfortunately, however, human behavior does not always follow logical patterns. Some health professionals take routine precautions for granted and may forget both the rationale for and importance of certain basic procedures and practices. This can lead to complacency and a false sense of security. Reasons for

this are varied, ranging from clinicians’ never seeing symptomatic patients or experiencing any infectious sequelae resulting from infection control breaches, to the extreme of not recognizing that they might have patients who could transmit infectious pathogens to them or their staff. They also may not realize how much the development and application of appropriate infection control practices has altered and lowered the potential for direct, indirect and aerosolized crossinfection. Why are these concerns important? Assessment of the state of the art of dental infection control, or any other science, reinforces a fundamental concept: we must know where we have been to understand where we are, so that we can determine where we should be going. In accord with this philosophy, a number of health care authorities—including the American Dental Association2-5 and the Centers for Disease Control and Prevention, or CDC6-8—historically have documented and reinforced aspects of disease prevention. Furthermore, methodologies for specific procedures, techniques and protocols have been detailed in targeted texts.9,10 The Journal of the American Dental Association has provided the profession with periodic ADA recommendations2-5 as well as numerous reviews of and updates on the subject over the years.11-17 Only a small representative sampling of these are referenced in this article, but one of them that must be highlighted here was written by James Crawford.11 His article provided a very insightful exploration of infectious disease challenges facing

JADA, Vol. 130, September 1999 Copyright ©1998-2001 American Dental Association. All rights reserved.

COVER STORY TABLE

REPRESENTATIVE MILESTONES IN INFECTIOUS DISEASES AND THEIR CONTROL. SCIENTIST

DATE 1546

CONTRIBUTIONS

Fracastoro

Reported concept of contagion and modes of disease transmission

van Leeuwenhoek

First described bacteria and protozoa (“animalcules”) under microscope; built first simple microscope

1750

Pringle

Observed relationship of putrefaction to disease; performed studies with agents he called “antiseptics”

1796

Jenner

Introduced smallpox vaccination as effective preventive method against disease outbreaks

1827

Alcock

Emphasized disinfectant properties of hypochlorite

1840s-1870s

Nightingale

Emphasized importance of sanitation; used statistics, surveillance and data collection

1843

Holmes

Applied epidemiology to demonstrate direct transmission of infection by health care personnel; demonstrated contagiousness of childbed fever (puerperal sepsis) from doctors and nurses

1861

Semmelweis

Instituted hospital procedures to reduce mortality from puerperal septicemia; emphasized role of hand hygiene in prevention of cross-infection

1860s-1870s

Lister

Was “father of clean and decent surgery”; introduced aseptic technique for surgery and care of wounds; introduced phenols (carbolic acid)

1860s-1880s

Pasteur

Established microbiology as a science; developed process of pasteurization

1870s-1880s

Koch

Isolated and demonstrated infectivity of anthrax bacillus; discovered Mycobacterium tuberculosis; formulated Koch’s postulates for infectious disease investigation; examined effects of numerous disinfectants against bacteria

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dentists, hygienists, assistants and laboratory technicians, and it suggested practical approaches to their resolution. As a result of his pioneering leadership and undaunted efforts, Crawford truly deserves the title he is too modest to acknowledge—the father of modern infection control in dentistry. What is the status of infection control in dentistry as the profession moves from one century to another, and into a new millennium? An answer stating that the practice of dentistry is much safer for both care providers and patients in 1999 than in 1899 would be correct in

large part. The list of accomplishments in procedures and technologies is extensive. A brief summary of some of the major areas addressed is found in the box, “Some 20th-Century Accomplishments in Infection Control.” There is another factor that is historically evident and difficult to calculate—health care worker compliance. Advancement in an area such as infection control requires acceptance and practice by the health care professionals performing the tasks. Although not unexpected, failures in compliance must be addressed quickly to minimize potential problems.

In this article, therefore, I will attempt to blend both aspects by addressing two primary topics: drepresentative 20th-century dental infection control successes (outlined in the box “Some 20thCentury Accomplishments ...”); dpatterns of compliance with recommended infection control practices, techniques and protocols among health care professionals. ASEPSIS: AN ESSENTIAL, ATTAINABLE GOAL

The principles of health care asepsis evolved long before the beginning of this century. References to the importance of

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EVOLUTION OF HANDPIECE STERILIZATION. d“Until handpieces can be replaced with models that can be routinely sterilized, scrubbing them in detergent solutions and wiping with alcohol is an alternative” (American Dental Association, 1978)2 d“Routine sterilization of handpieces is desirable; however, not all handpieces can be sterilized” (Centers for Disease Control, 1986)6 d“Routine between-patient use of a heating process capable of sterilization is recommended” (CDC, 1993)7 d“Although no documented cases of disease ... have been associated with ... handpieces, sterilization between patients with acceptable methods that ensure internal as well as external sterility is recommended” (ADA, 1996)5

hospital cleanliness and hygienic conditions in terms of preventing patient infection can be found in medical writings dating back to the fourth century B.C. In an excellent review of the history of hospital infections and early infection control considerations, Selwyn18 quoted the following fourth-century statement describing incorporation of these fundamental concepts into an Indian hospital’s physical design: “One portion at least should be open to the currents of the wind. It should not be exposed to smoke, or dust, or injurious sound or touch or taste or form or scent. ... After this should be secured a body of attendants of good behavior, distinguished for purity and cleanliness of habits.”19 It took many more centuries of observation and investigation for scientists and clinicians to come to the realization that microscopic organisms were the etiologies of infectious diseases. A number of dedicated people were responsible for the evolution of this knowledge, sometimes experiencing great risk to their own reputation and safety. While 1294

an exhaustive list of worthy contributors is not appropriate here, a few of the more prominent pioneers are acknowledged in the table. The simple act of handwashing. The activity that clearly is inherent throughout the spectrum of effective asepsis procedures is cleaning. We are constantly reminded to clean instruments before sterilizing them, clean surfaces before applying disinfectants, keep work areas clean, and clean dentures before spraying them with or immersing them in chemical agents. One activity singled out for specific mention in this “clean it first” category is the washing of hands by health care personnel. Semmelweis20 and Lister21 separately documented the importance of frequent hand-washing in preventing person-to-person microbial transmission. Once a link was established between hand-washing and infectious disease prevention, the practice became widespread. The clinical importance of this aspect of asepsis cannot be overstated. Hand-washing in health care facilities is the single most important infection control pro-

cedure for minimizing the potential development of nosocomial infections.22-24 Diligent hand-washing is a prime example of dental care professionals’ adopting an effective practice based on medical investigation and evaluation and subsequently expanding it to make the procedure a very visible cornerstone of their own precautions against infectious disease. It is not unusual to find dentists, hygienists and assistants washing their hands 30 or more times a day when treating patients. This level of compliance often is overlooked by those who wash their hands, but not by those who receive dental care.

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ith regard to patterns of health care worker compliance, the infection control challenge has not changed since early principles and procedures were established. Lack of hand-washing and other aseptic technique practices, with resultant nosocomial complications, have been reported in the medical literature. Common problems range from a failure to wash hands when indicated to not washing long enough.22-28 The overwhelming majority of dental health care workers have established a track record of professional safety for their patients and themselves by conscientiously adhering to the common-sense strategy of cleanliness inherent in the application of aseptic procedures. The ongoing challenge is to make certain that the rationale for and use of asepsis principles are routinely reinforced by incorporating them into all aspects of a practice’s infection control program.

JADA, Vol. 130, September 1999 Copyright ©1998-2001 American Dental Association. All rights reserved.

COVER STORY INSTRUMENT PROCESSING: DO NOT DISINFECT WHEN YOU CAN STERILIZE

Heat sterilization. Intense heat (in the form of fire) was used for many centuries to destroy the bodies of people who died of suspected transmissible diseases, as well as their clothing and household items. It was not until the end of the 18th century that Italian scientist Lazzaro Spallanzani was able to disprove the generally accepted theory of spontaneous microbial generation and demonstrate that organisms that he referred to as “superior animalcula” were destroyed by heat.29 While these findings spurred other investigators to further define the hightemperature conditions responsible for sterilization, other, little-recognized studies performed more than a century earlier by Papin led to the construction of a vessel that functioned by heating items under pressure.30 By the latter portion of the 19th century, early versions of the modern autoclave were developed and tested. This apparatus remains the most commonly used form of heat sterilization in health care facilities. Although implementation of effective infection control measures allows for the use of some choices in approach, sterilization of reusable dental instruments is one of the most important among the “must” category of practices. The traditional criterion for sterilization is an absolute—the destruction of all forms of microbial life. The historical state-of-the-art procedure in early 20th-century dental offices was to immerse instruments in a variety of chemical solutions and leave them for a variable period of time—a cold

sterilization process. Many problems of antimicrobial activity and instrument cleanliness were associated with this practice, and gradually the dental profession moved away from chemical exposure to physical heating processes. “In general, heat-sterilization in some form is the first choice,” Appleton30 wrote in 1950. “All things considered, it is superior in simplicity, economy, and effectiveness. Only when heat is physically impossible should dependence be put on chemical agencies.”

he application of heat sterilization modalities to reprocess an increasingly complex array of instruments did not stop with development of newer sterilizer technologies.

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Chemical sterilization. Chemical immersion containers were successfully replaced over the years with the routine use of multiple heat-sterilizer technologies—including autoclaving, dry heat, rapid heat transfer and unsaturated chemical vapor units—to the point where the use of immersion chemical sterilants and disinfectants is minimal or nonexistent in many dental practices. These changes in approach have resulted in no less than a revolutionary improvement in the procedures by which dental instruments are reprocessed between patient appointments. Thanks to the commitment of those responsible for preparing

instruments for patient treatment, one of the major achievements in the evolution of 20thcentury infection control in the health professions must be routine heat sterilization. The application of heat sterilization modalities to reprocess an increasingly complex array of instruments did not stop with development of newer sterilizer technologies. In fact, positive change has continued into the current decade. A prime illustration is the dental handpiece, historically classified in the “difficult-to-sterilize” category of instrumentation. Routine reprocessing of these motorized surgical instruments using heat, which began out of concern about microbial transmission, became another important success story for dentistry.31 Early difficulties associated with cleaning internal handpiece components, along with the inability of previous equipment models to withstand repeated subjection to high temperatures, prevented practitioners from accomplishing the desired infection control goal. It should be noted, however, that recommendations published by the ADA and the CDC in the 1970s and 1980s still acknowledged the necessity for improvement in heat stability and expressed a commitment to achieve the optimum result (Box, “Evolution of Handpiece Sterilization”). As a consequence of a concerted effort on the part of clinicians, engineers and handpiece manufacturers, treatment providers have gone from an “it would be nice” attitude toward this important aspect of infection control to a “yes we have” positive result. Patients need no longer ask what is being done to prevent cross-contamination and protect

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Figure 1. Historical practice of a dentist performing an intraoral examination on a patient without wearing latex gloves.

that the use of disposable gloves improved their aseptic technique and lowered the infection risk for their patients, the primary reason at the time for their use was to protect patients from the tissue-damaging effects of caustic antiseptic and disinfectant agents. As one might expect, many surgeons opposed wearing gloves, noting that they constricted the hands and made it impossible for them to perform delicate procedures.32 These same words could have been used decades later and attributed to other practitioners who initially resisted the conversion from bare-handed to gloved dentistry.

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Figure 2. Current practice of student treating patient while wearing appropriate latex gloves.

them; instead, they are able to see the sealed packages containing heat-reprocessed highand low-speed handpieces. PERSONAL PROTECTIVE EQUIPMENT: TRANSITION TO GLOVED DENTISTRY

A suggestion was made for covering physicians’ hands during surgery by Dr. Thomas Watson 1296

in 1843, 42 years before the first gloves were actually used by a physician. It was not until 1885 that the first surgeons’ gloves made of cotton were used.32 Rubber gloves were introduced into hospitals in 1890 by William Halstead, a professor of surgery at The Johns Hopkins University.33 Even though some surgeons felt

he ADA approached the issue of practitioners wearing disposable gloves through its Council of Dental Therapeutics in 1976, in an important publication aimed at protecting dental health care providers from the most infectious bloodborne occupational pathogen known at the time, hepatitis B virus. “The use of gloves in a practice should be encouraged through dental school training for those procedures in which there is bleeding,” the Council wrote.34 The language was strengthened and expanded in the first series of ADA and CDC infection control guidelines2-7; disposable gloves and other personal protective equipment have since been a core component of all recommendations to health professionals.2-7 Today’s dental students find it difficult to believe that many of their teachers, personal practitioners and family members were educated to provide treatment through “wet-fingered dentistry” (Figure 1). In today’s

JADA, Vol. 130, September 1999 Copyright ©1998-2001 American Dental Association. All rights reserved.

COVER STORY curricula, they are taught to routinely use gloves and other important protective barriers in their preclinical courses and to apply that practice to clinical experiences (Figure 2). They do not experience the trials of adaptation to latex gloves through which many of their predecessors struggled. Thus, clinicians who developed their technical expertise using bare hands have a very different perspective of occupational risks than that held by more recent graduates. Adaptation by the former group required both a philosophical commitment and a relearning of clinical competence. Incidents such as a glove’s becoming caught on a rotating bur (Figure 3) or instruments being dropped in the midst of treatment had to be overcome. As practitioners became more comfortable with this form of protection, the incidence of occupational infections changed forever. In addition to helping to reduce exposure to hepatitis B virus, the instances of herpetic whitlow (Figure 4), staphylococcal abscesses and chronic mycotic infections on the fingers and hands declined dramatically. Many dentists, hygienists and assistants who learned their professional techniques using gloves have never seen the above infections develop and/or recur in themselves or their colleagues. Therein lies the professional challenge. Practice transmission risks have been lowered significantly and patient care has become much safer, in part because of the use of gloves and other personal barriers. One does not need to develop one of these infections to make sure that the rationale for using

Figure 3. Accident that occurred during use of a dental handpiece. The operator’s glove became snagged in the rotating bur while the practitioner was treating a patient.

Figure 4. Recurrent herpes simplex virus infection on the finger of a dental assistant. The person had not worn gloves for the first years of practice and originally was infected occupationally while treating, without gloves, a patient who had a cold sore.

what is required to prevent them is diligently applied.35 SUMMARY

A long history of scientific, clinical and technological developments has led to the current recommendations for infection control in dentistry and

medicine. As a result, health care workers and their patients have never been better protected from occupational transmission of pathogens. This article considers only a few of the highlights of the dental infection control revolution. The list of areas considered could easily have

JADA, Vol. 130, September 1999 Copyright ©1998-2001 American Dental Association. All rights reserved.

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COVER STORY been more exhaustive— including, for instance, accomplishments in the clinical application of universal precautions, provision of dental care to an increasingly large percentage of immunocompromised patients, monitoring of heat sterilization units, and the significant decline in the incidence of exposures to contaminated sharps.

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he human factor also should not be overlooked as a major contributor to any success. Modifications in the way practitioners treat patients have come about primarily because the people providing care were convinced that the risks of infectious disease were real, the science was valid and appropriate preventive solutions were available. Many of the dental professionals who supported proposed recommendations in the 1970s and 1980s themselves had to adapt to a different clinical presentation of dentistry to the public. These were the movers and shakers who evaluated emerging evidence about infectious risks, and they addressed issues headon together with scientists, other clinicians and their professional organizations. Emerging and re-emerging infection control challenges will continue to confront the health profession in the 21st century. In addition, procedures aimed at preventing the spread of infectious disease are constantly being evaluated and updated. In some instances, equipment technology improvements will expedite care and diminish potential exposure to cross-contaminants, or new materials will be devel-

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oped for use as protective barriers. Among the important components of any infection control success, however, always will be remembering and understanding the rationale for appropriate practices. Visible and frequent reinforcement of the fundamental principles of asepsis, sterilization and protective barriers will not go out of style. ■ 1. U.S. Department of Labor, Occupational Safety and Health Administration. Occupational exposure to bloodborne pathogens: final rule. Fed Reg 1991;56:64004-82. 2. American Dental Association Council on Dental Materials and Devices, Council on Dental Therapeutics. Infection control in the dental office. JADA 1978;97:673-7. 3. American Dental Association Council on Dental Materials, Instruments, and Equipment, Council on Dental Practice, Council on Dental Therapeutics. Infection control recommendations for the dental office and the dental laboratory. JADA 1988;116:241-8. 4. American Dental Association. Infection control recommendations for the dental office and the dental laboratory. JADA 1992; 123(suppl):1-8. 5. American Dental Association Councils on Scientific Affairs and Dental Practice. Infection control recommendations for the dental office and the dental laboratory. JADA 1996;127:672-80. 6. Centers for Disease Control. Recommended infection control practices for dentistry. MMWR 1986;35:237-42. 7. Centers for Disease Control and Prevention. Recommended infection control practices for dentistry. MMWR 1993;41(RR-8):1-12. 8. Centers for Disease Control and Prevention. Recommendations for prevention and control of hepatitis C virus (HCV) infection and HCV-related chronic disease. MMWR 1998;47(RR-19):1-39. 9. Cottone JA, Terezhalmy GT, Molinari JA. Practical infection control in dentistry. 2nd ed. Baltimore: Williams & Wilkins; 1996. 10. Miller CH, Palenik CJ. Infection control and management of hazardous materials for the dental team. 2nd ed. St. Louis: Mosby; 1998. 11. Crawford JJ. State-of-the-art: practical infection control in dentistry. JADA 1985;110:629-33. 12. Cottone JA, Molinari JA. State-of-theart infection control in dentistry. JADA 1991;123:33-41. 13. Miller CH. Cleaning, sterilization and disinfection: basics of microbial killing for infection control. JADA 1993;124:48-56. 14. Runnells RR. Countering the concerns: how to reinforce dental practice safety. JADA 1993;124:65-73. 15. Molinari JA. Practical infection control for the 1990s: applying science to government regulations. JADA 1994;125:1189-97.

16. Shearer BG. Biofilm in the dental office. JADA 1996;127:181-9. 17. Cleveland JL, Gooch BF, Shearer BG, Lyerla RL. Risk and prevention of hepatitis C virus Dr. Molinari is proinfection. JADA 1999;130:641-7. fessor and 18. Selwyn S. Hoschairman, Departpital infection: the ment of Biomedical first 2500 years. J Sciences, University Hosp Infect 1991; of Detroit Mercy, 18(suppl A):5-64. School of Dentistry, 19. Charaka8200 West Outer Samhita. Vol. 1. Drive, Detroit, Mich. Translated from San48219-0900. skrit to English by Address reprint Kavipatna AC. Calrequests to Dr. Molicutta, India: privately nari. printed; 1888:168-9. 20. Semmelweis I. The genesis of puerperal fever (childbed fever). Lecture presented May 15, 1850; Vienna, Austria. 21. Lister J. On the antiseptic principle of the practice of surgery. Brit Med J 1867;2:353-6;668-9. 22. Garner JS, Favero MS. CDC guideline for handwashing and hospital environmental control, 1985. Infect Cont 1986;7:231-5. 23. Larson E. A causal link between handwashing and risk of infection? Examination of the evidence. Infect Control 1988;9:28-36. 24. Bryan JL, Cohran J, Larson EL. Handwashing: a ritual revisited. Crit Care Nurs Clin North Am 1995;7:617-25. 25. Larson EL. APIC guideline for handwashing and hand antisepsis in health care settings. Am J Infect Control 1995;23:251-69. 26. Albert RK, Condie F. Hand-washing patterns in medical intensive care units. N Engl J Med 1981;304:1465-6. 27. McLane C, Chenelly S, Sylwestrak ML, Kirchhoff KT. A nursing practice problem: failure to observe aseptic technique. Am J Infect Control 1983;11:178-82. 28. Quraishi ZA, McGuckin M, Blais FX. Duration of handwashing in intensive care units: a descriptive study. Am J Infect Control 1984; 11:83-7. 29. Spallanzani L. Tracts on the nature of animals and vegetables: observations and experiments upon the animalcula of infusions. Lecture presented 1799; Edinburgh, Scotland. 30. Appleton JLT. Bacterial infection in dental practice. Philadelphia: Lea & Febiger; 1950:116-29. 31. Molinari JA. Dental handpiece sterilization: historical and technological advances. Compend Contin Educ Dent 1998;19:724-8. 32. Cartwright FF. The development of modern surgery. London: Barker; 1967:81. 33. Garrison FH. An introduction to the history of medicine. 4th ed. Philadelphia: Saunders; 1929:731. 34. ADA Council on Dental Therapeutics. Type B (serum) hepatitis and dental practice. JADA 1976;92:153-9. 35. Molinari JA. Infection-control accomplishments: learning the lessons of history. Compend Contin Educ Dent 1996;17:114-6.

JADA, Vol. 130, September 1999 Copyright ©1998-2001 American Dental Association. All rights reserved.