Dentistry & Health Care Idiopathic Pulmonary Fibrosis: A Newly-identified Occupational Hazard for Dentists

The practice of dentistry is associated with a variety of occupational hazards. These are largely preventable, or can be minimized, by taking precautions to reduce the risk of exposure. Occupational hazards can largely be categorized as risk of exposure to chemicals and other noxious substances, risk of physical injury, and risk of infection and disease transmission.1Saccucci M, Ierardo G, Protano C, Vitali M, Polimeni A. How to manage the biological risk in a dental clinic: current and future perspectives. Minerva Stomatol 2017;66(5):232-9.,2Bârlean L, Dănilă I, Săveanu I, Balcoş C. Occupational health problems among dentists in Moldavian Region of Romania. Rev Med Chir Soc Med Nat Iasi 2013;117(3):784-8.,3Centers for Disease Control and Prevention. Infection prevention & control guidelines & recommendations. Summary of infection prevention practices in dental settings: Basic expectations for safe care. Available at: https://www.cdc.gov/oralhealth/infectioncontrol/guidelines/index.htm.,4Occupational Health and Safety Administration. Available at: www.osha.org. Most recently, idiopathic pulmonary fibrosis, a fatal lung disease, has been identified as an occupational hazard in dentistry.

Idiopathic Pulmonary Fibrosis

Recently, a newly identified work-related hazard for dentists and dental personnel was identified by the Centers for Disease Control and Prevention (CDC) in the United States.5Nett RJ, Cummings KJ, Cannon B, Cox-Ganser J, Nathan SD. Dental personnel treated for idiopathic pulmonary fibrosis at a tertiary care center – Virginia, 2000-2015. Morb Mortal Wkly Rep 2018;67(9):270-3. Data from a tertiary care hospital revealed that between 2000 and 2015, 894 patients were treated for idiopathic pulmonary fibrosis (IPF) including 8 dentists and 1 dental technician. Their mean age was 64 years, 7 of the 9 patients had died, and the median time of survival from initial diagnosis was 3 years. (Table 1)

IPF is a progressive pneumonia that involves scarring of the lungs and fibrosis of the interstitial areas due to ongoing deposition of collagen in the cells that line the bronchial alveolar spaces. While the cause of IPF is not fully understood, this disorder has been associated with exposure to cigarette smoke, viral infection, metal and coal dust, and agricultural environments.6Kuehn B. Dentists at risk of lung disease? J Am Med Assoc 2018;319(16):1650. IPF is a chronic condition with a median survival of 3 to 5 years.7Richeldi L, Collard HR, Jone MG. Idiopathic pulmonary fibrosis. Lancet 2017;389(10082):1941-52.

This was the first known IPF cluster among persons in the dental profession. Based on the regional population and number of dentists, this cluster represents an almost 23 times higher rate of occurrence. The CDC report noted limitations of the analysis, including data from only one center, and lack of complete information regarding environmental exposures. However, the report also noted that dentists and others in the profession are exposed to a wide range of inhaled environmental hazards, which may pose a significant risk for the development of IPF in the absence of personnel protective equipment and other safety precautions.

Dentists and others in the profession are exposed to a wide range of inhaled environmental hazards, which may pose a significant risk for the development of IPF in the absence of personal protective equipment and other safety precautions.

Other Lung Disorders

While relatively uncommon overall,8Chung SJ, Koo GW, Park DW, Kwak HJ, Yhi JY, Moon JY, Kim SH, Sohn JW, Yoon HJ, Shin DH, Park SS, Pyo JY, Oh YH, Kim TH. Pulmonary foreign body granulomatosis in dental technician. Tuberc Respir Dis (Seoul) 2015;78(4):445-9. occupational lung disease has been reported more often in dental technicians than in dentists. Lung disorders affecting dental technicians globally include reduced lung function, silicosis, asbestosis, granulomatosis, asthma, and pneumoconiosis.8Chung SJ, Koo GW, Park DW, Kwak HJ, Yhi JY, Moon JY, Kim SH, Sohn JW, Yoon HJ, Shin DH, Park SS, Pyo JY, Oh YH, Kim TH. Pulmonary foreign body granulomatosis in dental technician. Tuberc Respir Dis (Seoul) 2015;78(4):445-9. These have been associated with a lack of, or insufficient, protection (e.g., dust masks) against exposure to chrome-cobalt-molybdenum alloys, beryllium, silica, asbestos, acrylic dust and/or other materials. In a CDC report, silicosis was confirmed in nine dental laboratory technicians in a variety of locations in the United States between 1994 and 2000, associated with exposure to silica dust.9CDC. Silicosis in dental laboratory technicians — five states, 1994—2000. Morb Mortal Wkly Rep 2004;53(09):195-97. In one of the cases, asbestosis and berylliosis were also diagnosed. (Table 1)

Further, in 2017 it was reported that 6 older dentists in the United States had been diagnosed with malignant mesothelioma associated with brief exposures to asbestos-containing dental tape, which was used for casting rings until the 1970s.10Markowitz SB, Moline JM. Malignant mesothelioma due to asbestos exposure in dental tape. Am J Ind Med 2017;60(5):437-2. (Table 1) Four cases of dentists with mesothelioma were also reported in Italy in a 2017 publication, and one case previously. These were rare tragic occurrences, but preventable with proper precautions.11Mensi C, Ciullo F, Barbieri GP, Riboldi L, Somigliana A, Rasperini G, Pesatori AC, Consonni D. Pleural malignant mesothelioma in dental laboratory technicians: A case series. Am J Ind Med 2017;60(5):443-8.

Table 1. Lung diseases identified as occupational hazards in dental professionals and personnel
Idiopathic pulmonary fibrosis
Silicosis
Asbestosis
Granulomatosis
Asthma
Pneumoconiosis
Berylliosis
Malignant mesothelioma

Respiratory hypersensitivity has also been reported among dentists and dental personnel. In Finland, 62 cases were diagnosed between 1989 and 1998, compared to 2 cases from 1975 up until 1989. By 1995 respiratory hypersensitivity was twice as prevalent as in the general population.12Piirilä P, Hodgson U, Estlander T, Keskinen H, Saalo A, Voutilainen R, Kanerva L. Occupational respiratory hypersensitivity in dental personnel. Int Arch Occup Environ Health 2002;75(4):209-16. Of 28 cases of rhinitis and asthma reported, 24 resulted from exposure to methacrylates.12Piirilä P, Hodgson U, Estlander T, Keskinen H, Saalo A, Voutilainen R, Kanerva L. Occupational respiratory hypersensitivity in dental personnel. Int Arch Occup Environ Health 2002;75(4):209-16. Among almost 800 dental assistants, daily exposure to methacrylates resulted in a more than two-fold increased risk of adult-onset asthma, as well as a 37% and 69% increased risk, respectively, of nasal hypersensitivity or a cough/phlegm.13Jaakkola MS, Leino T, Tammilehto L, Ylöstalo P, Kuosma E, Alanko K. Respiratory effects of exposure to methacrylates among dental assistants. Allergy 2007;62(6):648-54. (Figure 1) Among individuals at greater risk for atopic disease, the risk of asthma was increased by more than 300%. Further, a dose-response relationship was observed.13Jaakkola MS, Leino T, Tammilehto L, Ylöstalo P, Kuosma E, Alanko K. Respiratory effects of exposure to methacrylates among dental assistants. Allergy 2007;62(6):648-54.

Figure 1. Increased risk for condition with daily exposure to methacrylates



Among almost 800 dental assistants, daily exposure to methacrylates resulted in a more than two-fold increased risk of adult-onset asthma.

Risk of transmission of microorganisms and infectious diseases

Risk of exposure to microorganisms in the dental setting is well-recognized, including those causing diseases affecting the lungs. An Austrian study in 1987 concluded that dentists and dental personnel were at increased risk of Legionella infection.14Reinthaler F, Mascher F, Stünzner D. Legionella pneumophila: seroepidemiologic studies of dentists and dental personnel in Austria. [Article in German] Zentralbl Bakteriol Mikrobiol Hyg B 1987;185(1-2):164-70. However, a meta-analysis of 7 studies found no evidence of increased risk of Legionella infection for dental personnel for studies conducted after 1998, attributed to infection control protocols and possibly differences in the municipal water supply.15Petti S, Vitali M. Occupational risk for Legionella infection among dental healthcare workers: meta-analysis in occupational epidemiology. BMJ Open 2017;7(7):e015374. doi: 10.1136/bmjopen-2016-015374. This concurs with the finding of a similar risk level to the general population in ADA Health Screening Programs conducted between 2002 and 2012,16Estrich CG, Gruninger SE, Lipman RD. Rates and predictors of exposure to Legionella pneumophila in the United States among dental practitioners: 2002 through 2012. J Am Dent Assoc 2017;148(3):164-171. and highlights the importance of infection control protocols. In 2014, transmission of Mycobacterium tuberculosis and subsequent active tuberculosis (TB) was reported in an office. However, recommended infection control protocols and policies related to TB had not been followed.17Merte JL, Kroll CM, Collins AS, Melnick AL. An epidemiologic investigation of occupational transmission of Mycobacterium tuberculosis infection to dental health care personnel: infection prevention and control implications. J Am Dent Assoc 2014;145(5):464-71.

A meta-analysis of 7 studies found no evidence of increased risk of Legionella infection for dental personnel for studies conducted after 1998, attributed to infection control protocols and possibly differences in the municipal water supply.

Implications for Dentistry

Appropriate personal protective equipment is essential to prevent and reduce injury, disease transmission and exposure to chemicals and other potentially noxious materials. Additional measures needed to reduce risk of exposure and infection with pathogens include inoculations, hand hygiene, personal protective equipment, and adherence to other infection prevention and control measures.

The individuals diagnosed with IPF began practice at a time when the profession was not as concerned about occupational exposure as it is today. The need for respiratory protection in emphasized by the CDC report, and National Institute for Occupational Safety and Health-certified respirators have been recommended.6Kuehn B. Dentists at risk of lung disease? J Am Med Assoc 2018;319(16):1650. Individuals with sensitivity/allergies to specific chemicals and materials should avoid their use. Chemicals and materials must be handled and stored in accordance with the manufacturer’s instructions for use, recommendations and regulations. Further, safety and health requirements must be met. Safety data sheets provide detailed information on chemicals, hazards, avoiding and treating exposures.

Chemicals and materials must be handled in accordance with the manufacturer’s instructions for use, recommendations and regulations, and safety and health requirements must be met.

Conclusions

Dentists, dental personnel and dental technicians must be aware of occupational risks associated with dentistry, including inhaled hazards. It is essential that dentists, dental personnel and dental technicians diligently follow established infection control and prevention guidelines, and health and safety regulations, designed to reduce the risk of injury, transmission of microorganisms and disease, and the risk of exposure to noxious substances.

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