Researchers at the Centres for Disease Control and Prevention (CDC) in the USA are investigating why a cluster of dentists were diagnosed with a rare lung disease called idiopathic pulmonary fibrosis (IPF)[i]. In one Virginia clinic, nine dental professionals have been treated in the last 15 years. During 2016, dentists accounted for an estimated 0.038% of US residents, yet represented 0.893% of patients treated at this clinic, which is 22.5 times more than expected.
IPF is a chronic disease, the cause of which is primarily unknown. Symptoms include unexplained shortness of breath that gradually becomes worse, which may be accompanied by a nonproductive cough. It has previously been associated with occupations, including farming, work with livestock, hairdressing, exposure to metal dust, work with birds, stone cutting/polishing and exposure to vegetable or animal dust[ii]. Smoking and viral infections have also been suggested as possible contributing factors. IPF is usually fatal, with the median survival time being around 3 years[iii].
In April of 2016, a dentist diagnosed with IPF at the Virginia clinic contacted CDC to report concerns that IPF had been diagnosed in other dentists in the same area. The medical records of all patients treated for IPF at the clinic, between September of 1996 and June of 2017, were checked for evidence of work in the dental industry. Nine patients, (eight dentists and one technician) were dental professionals, and all were treated since 2000. Seven of them had died. Three patients were former smokers, one had never smoked, and smoking history was unknown for five. One patient reported polishing dental appliances and preparing amalgams and impressions without respiratory protection. Some substances used in these tasks have potential respiratory toxicity, such as silica, polyvinyl siloxane, alginate and others. The researchers concluded that, even though no clear etiology could be determined, occupational exposures may have contributed towards the onset of IPF. Limitations of the study were that several of the patients were smokers (a contributing factor) and only one was available for interview.
Although this is the first report of IPF in dentists, four years of National Occupational Respiratory Mortality System data indicate that dentists, or workers in offices of dental practice, were more likely to die as a consequence of ‘other interstitial pulmonary diseases with fibrosis’ than the general population.
The report concludes that dental personnel should wear adequate respiratory protection if other control methods, such as improved ventilation, are not practical or effective. Further investigation of this cluster of cases is warranted.
[i] Nett, R. J. Dental Personnel Treated for Idiopathic Pulmonary Fibrosis at a Tertiary Care Center — Virginia, 2000–2015. MMWR Morb Mortal Wkly Rep 67, (2018) <https://www.cdc.gov/mmwr/volumes/67/wr/mm6709a2.htm?s_cid=mm6709a2_w> (Accessed 24 April 2018).
[ii] Baumgartner, K. B. et al. Occupational and Environmental Risk Factors for Idiopathic Pulmonary Fibrosis: A Multicenter Case-Control Study. Am J Epidemiol 152, 307–315 (2000). <https://academic.oup.com/aje/article/152/4/307/67670> (Accessed 24 April 2018).
[iii] Dempsey, O. J., Kerr, K. M., Gomersall, L., Remmen, H. & Currie, G. P. Idiopathic pulmonary fibrosis: an update. QJM 99, 643–654 (2006). <https://academic.oup.com/qjmed/article/99/10/643/2261118> (Accessed 24 April 2018).