Infection Control in Primary Dental Care

By Martin R. Fulford and Nikolai R. Stankiewicz

This book is an easy-to-use guide to all aspects of infection control and decontamination that will support the implementation of effective measures for risk reduction in dental practice. Among the topics addressed are the principles and practicalities of cleaning and sterilizing dental instruments, the role of personal protective equipment, the design and use of decontamination rooms, choice of dental equipment, environmental disinfection, and considerations relating to dental unit water lines. In addition, readers will find an informative and helpful section on the background history and basic science of infection control within dentistry. Infection Control in Primary Dental Care will be very useful for all members of the dental team, including dentists, dental nurses or assistants, dental hygienists, and therapists. The book is illustrated with photographs, diagrams, and tables to aid understanding and encourage good practice. The authors have a background in microbiology anddental practice and have extensive experience of providing advice and guidance to professional colleagues on infection control procedures.

• Language: English
• Publisher: Springer
• Release date: Jul 4, 2019
• ISBN: 9783030163075

Book preview

Part IBasic Science of Infection Control

© Springer Nature Switzerland AG 2020

Martin R. Fulford and Nikolai R. StankiewiczInfection Control in Primary Dental CareBDJ Clinician’s Guideshttps://doi.org/10.1007/978-3-030-16307-5_1

1. A History of Infection Control

Martin R. Fulford¹  and Nikolai R. Stankiewicz²

(1)

Wedmore, Somerset, UK

(2)

East Lydford, Somerset, UK

1.1 Semmelweis

1.2 The Germ Theory of Disease

1.3 Infection Control in Dentistry Emerges

1.4 Hepatitis

1.5 The Steam Age

1.6 HIV/AIDS and a New Era of Infection Control

1.7 Prions

1.8 Learn from the Past

Further Reading

1.1 Semmelweis

In 1847 Ignaz Semmelweis (Fig. 1.1), a doctor undertaking obstetrics in a hospital in Vienna, did an audit much like we would do today. He investigated the postdelivery mortality rates of mothers, with startling results. If a doctor or medical student was to deliver a baby, the chance of the mother dying was as high as 18%, but if a midwife or midwifery student was to deliver the baby, the death rate dropped to 2%.

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Fig. 1.1

Portrait of Ignaz Philipp Semmelweis (1818–1865), Hungarian-Austrian physician. Credit: Wellcome Collection. https://​creativecommons.​org/​licenses/​by/​4.​0/​

Semmelweis rigorously assessed what factors could explain the different death rates between the two groups and noted that unlike the midwives, the doctors would at times undertake autopsies upon cadavers then as needed go to the maternity ward and deliver babies. Semmelweis concluded that the doctors were becoming contaminated by the cadavers and passing on something deadly to the mothers. So, he came up with a simple solution; he got the doctors to wash their hands. He redid his audit and found the intervention worked, and the death rate for the mothers dropped to 2% when the doctors delivered the babies.

Semmelweis demonstrated two important principles:

1.

Healthcare has the potential to make people sick. We call this nosocomial infection.

2.

Interventions can be undertaken to reduce this risk; we call this infection control.

Unfortunately for Semmelweis he was ahead of his time. His superiors did not attribute the handwashing to the improved survival rates, instead crediting the hospital’s newly installed ventilation system. This was because at that point in history infections were thought to be spread by miasma, foul smelling air.

1.2 The Germ Theory of Disease

It was not until the work of Louis Pasteur, Jacob Henle and Robert Koch from the 1860s onwards that the paradigm of miasma as the source of infection would be challenged. The germ theory of disease proposed that microorganisms were responsible for infections. Joseph Lister (Fig. 1.2) became aware of Pasteur’s research and with time formulated methods of delivering antiseptic surgery, publishing his initial findings in 1867. Embraced by some, there were still many in the medical establishment that were resistant to Lister’s methods. However, by the end of the nineteenth century, the success of those that did adopt his techniques became too many to ignore.

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Fig. 1.2

Joseph Lister, 1st Baron Lister (1827–1912) surgeon. Credit: Wellcome Collection. https://​creativecommons.​org/​licenses/​by/​4.​0/​

Lister’s research sought to find chemicals that would disinfect not only the wounds he operated on (antisepsis) but also the hands of the operators and the instruments (asepsis). Word spread of Lister’s methods in Europe and America, and this prompted further developments by those enthused by his work. The harsh phenols advocated by Lister in cleaning instruments prompted William Halsted to commission the Goodyear Rubber Company to make rubber gloves, which were then worn by theatre nurses and then his colleague Joseph Bloodgood started using them to undertake surgery.

1.3 Infection Control in Dentistry Emerges

In 1891 Willoughby Miller wrote about disinfection of dental instruments in reducing the risk of patient-to-patient transmission of infection, citing examples of spread of syphilis due to dental care. Miller’s recommendations included the boiling of linen and the single use of rubber dam. A salient observation Miller made was that bioburden remaining on instruments reduces the efficacy of chemicals to sterilise instruments, and he recommends they are scrubbed first. Boiling water is cited as the preferred method of instrument reprocessing during this period. The efficacy of boiling surgical instruments had been demonstrated in 1888 by Hugo Davidsohn. A 1902 article by Young describes how a device to boil dental instruments could easily be made.

Perhaps one of the most telling and thought-provoking articles to be published around this time was penned by Fossume in 1905 who opined that frequent reasons dentists were not following infection control measures of the time were time and cost; plus ça change! He goes on to argue that the implementation of infection control is a moral and intellectual obligation of the modern dentist, calling upon the values of professionalism.

By 1915 in the USA, there were guidelines on infection control in dentistry issued by the Public Health Service under the auspices of the Hygienic Laboratory, which would later become part of the National Institutes of Health. This guidance by H. E. Hasseltine encompassed asepsis, validation, cross infection, instrument reprocessing including the role of cleaning prior to sterilisation and methods of sterilisation. Whilst autoclaves and Arnold (non-pressure) devices were noted for their role in preparing linen and glassware, boiling water is favoured for instruments. Moist heat was deemed essential by Hasseltine in sterilising instruments, with a jacketed water bath described that maintained a temperature of 80° C. A section was dedicated to reprocessing handpieces and the problems this might pose, something we still are challenged by today. Single-use instruments and equipment were detailed, including endodontic files and paper cups for patients. He highlighted the role dental schools had in educating in infection control. The guidance also encompassed the surgery and dental chair, the maintenance of the cuspidor and the role of protective barriers, albeit linen as compared to the single-use plastics we use today.

1.4 Hepatitis

McDonald proposed in 1908 that infectious jaundice was due to a virus. It was MacCallum in 1947 who went on to classify viral hepatitis as A (infectious) or B (serum). By the 1940s there was an increasing awareness of viral hepatitis posing a public health problem in many parts of the world. In 1952 an expert panel came together as part of the World Health Organization to address the problems posed by hepatitis. The panel were unsure how hepatitis B might be spread, but they were sure that parental penetration of needles contaminated with blood would transmit the disease. It is worth noting that up until the mid-1950s hypodermic needles and syringes were normally reused. This accounts for why hepatitis epidemics would break out after vaccination programs. Subsequently, dentistry was recognised as being a potential risk in the transmission of hepatitis B. Amongst the panel’s recommendations on invasive surgical instrument reprocessing was that chemical disinfectants should not be used as they could not be relied upon to be effective.

It was not until 1963 with the discovery of the Australia antigen (hepatitis B surface antigen) by Baruch Blumberg and Harvey Alter that progress in the understanding of the virus increased at a greater pace. The first commercial vaccination against hepatitis B, developed by Maurice Hilleman, was released in 1981. Papers soon appeared in dental journals recommending its use by the profession. Unfortunately, the uptake of the vaccine by the dental profession remains low in many countries due to a range of factors.

1.5 The Steam Age

Charles Chamberland and Pasteur’s invention of the autoclave in 1879 would prove to be an even more effective method of destroying microorganisms than using chemicals. Ernst von Bergmann and his assistant Schimmelbusch began steam sterilisation of surgical dressings in 1885. By the 1890s steam sterilisers were in use in some American hospitals. There were various changes in sterilising machines over the years, but it was in 1933 that the American Sterilizer Company would introduce the first machine that used temperature indicators, rather than just pressure, thereby improving the control and accuracy of the process and heralding what Perkins described as the ‘modern era of sterilisation’.

From the mid-1950s onwards, the cost of automatic autoclaves that were quick to run had started to come down in price, making them more affordable and practical for general dental practice. In the late 1950s, articles started appearing in dental journals supporting the use of autoclaves in dentistry to reduce the risk of spreading hepatitis B, especially given that case reports around this time also suggested multiple cases of hepatitis transmission due to dental care. It may come as a surprise for more recent members of the dental team to learn that even in the mid-1980s, boiling instruments in water remained a popular means of reprocessing instruments in the UK, despite only disinfecting them at best. More recent studies have shown that in some developing countries, boiling instruments persists as a method of reprocessing.

Spaulding proposed in 1957 that surgical and medical instruments be reprocessed based on the risk of associated infection. Instruments used within body cavities would be classed as critical; those in contact with mucous membranes or non-intact skin would be semi-critical, and those instruments that only touch intact skin would be classed as non-critical. This system is still largely used in dentistry, but for ease semi-critical instruments are often reprocessed as if critical. The problem with the Spaulding’s system is it was based on the available knowledge at the time about microbiology. Since then, it has become evident that there are pathogens that will escape eradication unless the instruments they contaminate are cleaned before sterilization, rather than just disinfected even if classed as semi-critical.

In the 1950s, UK hospitals began centralising their sterilisation services. This was done to achieve a uniform standard of reprocessing, better maintenance of equipment and well-trained staff. By the mid-1960s there were advocates of doing the same within general dental practice, rather than undertaking instrument reprocessing in treatment areas. This remains a challenge for many practices that are not located in purpose built premises.

1.6 HIV/AIDS and a New Era of Infection Control

In 1980 the World Health Organization announced that smallpox had been eradicated. That same year in the USA would see increasing numbers of homosexual men developing unusual opportunistic infections and cancers including Pneumocystis carinii and Kaposi’s sarcoma, marking the beginning of the acquired immune deficiency syndrome (AIDS) epidemic. By 1984 researchers in France and the USA had identified that AIDS was due to a virus, human immunodeficiency virus (HIV).

In the USA by the 1960s, hospitals for infectious diseases had been replaced by isolating patients in wards within general hospitals. The Centers for Disease Control and Prevention (CDC) issued guidance on how to manage infectious patients based on epidemiologic risk factors in 1970, and revised in 1975, including blood precautions. The emergence of AIDS would become a major factor in re-evaluating this methodology, and new guidance was released in 1983, which included guidance on the management of patients’ blood and body fluids. The use of personal protective equipment, including gloves and masks, was highlighted as being important in protecting healthcare workers.

A fundamental problem with the 1983 guidance was that it was for managing patients who were known to be infectious. This ignored those in the population who were yet to be diagnosed, healthy carriers or those that failed to disclose an infection. The release of the 1985 guidance, universal precautions, recognised this deficiency and advised that all blood and some body fluids should be considered infected.

The response to AIDS by government, health organisations and the public demonstrates the complex nature which societies can respond to infectious disease. The early years of the AIDS epidemic saw governments fail to get to grip with the problem based on political ideology and values. The media created fear and spread misinformation. Various public health measures were wasteful by not specifically targeting those at greater risk. The already marginalised in society were vilified and blamed for the disease, due to the ensuing fearmongering. The momentum behind this did however force dentists to look at their infection control measures, with the adoption of universal precautions.

In 1990 an