CDC Finds Cluster of Pulmonary Disease in Dentists

Troy Brown, RN

March 08, 2018

The first cluster of idiopathic pulmonary fibrosis (IPF) was identified among nine dental personnel seen at a tertiary care center between 2000 and 2015, a number 23 times higher than expected, the Centers for Disease Control and Prevention (CDC) reports.

IPF has been linked to other occupations; however, these are the first published data to show a link with dentistry, the authors explain. Dental workers' exposures include infectious agents, chemicals, airborne particulates, ionizing radiation, and other potentially hazardous materials.

"It is possible that occupational exposures contributed to this cluster," the researchers write.

Randall J. Nett, MD, from the Respiratory Health Division, National Institute for Occupational Safety and Health, CDC, and colleagues report their findings in an article published in the March 9 issue of the Morbidity and Mortality Weekly Report.

A dentist undergoing treatment for IPF at the specialty care center in Virginia contacted the CDC to report that several other dentists were also receiving treatment there for the disorder in April 2016. The CDC researchers then reviewed the medical records of all 894 patients treated there for IPF between September 1996 and June 2017, to determine how many of them had worked as a dentist, dental hygienist, or dental technician.

They identified eight (0.9%) dentists and one (0.1%) dental technician who had undergone treatment between 2000 and 2015. Seven had died, between 1 and 7 years (median, 3 years) after initial consultation. All patients were men, aged 49 to 81 (median, 64) years. Nett and colleagues were only able to interview one of the two living patients — the one who had contacted the CDC.

Of five patients for whom symptom information was available, two had exertional dyspnea, three had shortness of breath, one had decreased exercise tolerance, one had a productive cough, and one had throat clearing. Tobacco use was recorded for four patients, three were former smokers, and one had never smoked.

Pulmonary function data were available for eight patients. The researchers defined lung restriction as restrictive spirometry and low lung volumes. Three had normal function, two had mild restriction, one had moderate restriction, one had severe restriction, and one had restriction that could not be classified.

The living patient who had not completed an interview underwent a lung transplant 3 years after diagnosis.

Computed tomography results were available for seven patients. One had extensive basilar honeycombing; one had extensive honeycombing and traction bronchiectasis; one had basilar subpleural fibrosis and diffuse peripheral septal thickening with cystic changes; one had advanced fibrosis, honeycombing, and bullous and cystic lesions; one had peripheral reticular infiltrates; one had bibasilar infiltrates and bibasilar honeycombing; and one had mild to moderate subpleural fibrosis with bibasilar honeycombing.

The living patient who had been interviewed had never worn a National Institute for Occupational Safety and Health-certified respirator during dental activities throughout his 40-year practice as a dentist, although he did wear a surgical mask during the last 20 years of his practice. He never smoked.

His activities included polishing dental appliances, preparing dental amalgams and impressions, and using film developing solutions to develop X-rays. In addition, he reported work-related dust exposure when he worked as a street sweeper for 3 months before he entered dental school and intermittent environmental exposure to dust from coral beaches for about 15 years when he visited the Caribbean region as a dentist.

"Inhalational exposures experienced by dentists likely increase their risk for certain work-related respiratory diseases. For example, cases of dental technicians with pneumoconiosis, a restrictive occupational lung disease resulting from inhalation of dust, have been identified after exposure to either silica or cobalt-chromium-molybdenum-based dental prostheses," the authors write.

Unpublished data from a query of the National Occupational Respiratory Mortality System of those with " 'other interstitial pulmonary diseases with fibrosis' (which would include IPF) listed as the underlying or contributing cause of death" revealed proportionate mortality ratios of 1.52 (95% confidence interval, 1.05 - 2.11) among those who had worked in dental offices and 1.67 among dentists (95% confidence interval, 1.01 - 2.61). "These findings suggest that a higher rate of IPF might occur among dental personnel than among the general population," Nett and colleagues write.

Limitations of the current findings include the fact that these patients were treated in a specialty clinic, which could indicate higher socioeconomic status and could overrepresent dentists. As these data did not include those treated at other facilities, the magnitude of the cluster could be higher. The involvement of past occupational exposures could not be fully explored, as only one patient was interviewed, and exposures included nonoccupational exposures known to be risk factors for IPF. Finally, the researchers were unable to assess histological commonalities among the patients, as there were no biopsy specimens available.

The researchers estimate that approximately 650,000 dental personnel (122,330 dentists) were employed in the United States during 2016. "This cluster of IPF cases reinforces the need to understand further the unique occupational exposures of dental personnel and the association between these exposures and the risk for developing IPF so that appropriate strategies can be developed for the prevention of potentially harmful exposures," they explain.

The authors have disclosed no relevant financial relationships.

Morb Mortal Wkly Rep. 2018;67;270-273. Full text

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