Pleural malignant mesothelioma in dental laboratory technicians: A case series

Our plain-English summary of Pleural malignant mesothelioma in dental laboratory technicians: A case series, by C. Mensi, F. Ciullo, G.P. Barbieri, et al (American Journal of Industrial Medicine, 2017).

The study

• Authors: C. Mensi, F. Ciullo, G.P. Barbieri, L. Riboldi, A. Somigliana, G. Rasperini, A.C. Pesatori, D. Consonni
• Journal: American Journal of Industrial Medicine
• Published: 2017;60(5):443-448
• Type of article: Case report
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos was used in dentistry as a binder in periodontal dressings and as lining material for casting rings and crucible. However, until now, only one case of malignant mesothelioma with occupational exposure to asbestos in dental practice has been reported. We present 4 pleural mesotheliomas out of 5344 cases identified in Lombardy, Italy, in 2000-2014. Three men had been working as dental laboratory technicians, with asbestos exposure for 10, 34, and 4 years, and one woman had been helping her husband for 30 years in manufacturing dental prostheses. The men described the use of asbestos as a lining material for casting rings, while the woman was not able to confirm this use. We confirm the association of malignant mesothelioma with dental technician work. Dental technicians suffering from mesothelioma should be questioned about past occupational asbestos exposure.

© 2017 Wiley Periodicals, Inc.

In plain English

This case series came from the Lombardy Mesothelioma Registry in northern Italy. Among 5344 mesothelioma cases diagnosed in 2000-2014, the authors found four people with pleural malignant mesothelioma, in the lining of the lungs, who had worked in dental laboratories. Three were men who had been dental technicians. The fourth was a woman who helped her husband make dental prostheses from 1961 to 1991; for that work, the authors could document only indirect asbestos exposure. She also reported holding an asbestos-cement slab while her husband drilled it. One man used asbestos-lined casting cylinders until 1957 and wore asbestos gloves; another cut asbestos from rolls to line casting rings twice a week for 10 years. The first man's lung tissue held 22,000 asbestos bodies per gram of dry tissue (95% confidence interval 16,000 to 30,000); asbestos fibers were below the detection limit of 380,000 per gram. None of the patients knew the asbestos type used. Survival ranged from 8.0 months to 4.3 years. The authors concluded that two cases had definite and two had possible occupational asbestos exposure. Only the first patient received workers' compensation.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Case series (four cases) drawn from a regional mesothelioma registry
• Who was studied: Four patients with pleural malignant mesothelioma who had worked in a dental laboratory (three men aged 72, 79 and 70; one woman aged 61), found among 5344 incident mesothelioma cases recorded by the Lombardy Mesothelioma Registry, Italy, diagnosed 2000-2014
• Exposure: Asbestos used in dental prosthesis making by wax model casting: asbestos-lined casting cylinders and rings, asbestos cut from rolls for lining rings, and asbestos gloves. Exposure was classified as definite for patients 1 and 4 and possible for patients 2 and 3. The asbestos type was not known to the patients.
• Main results:
  • Patient 1, a 72-year-old man, worked as a dental technician from 1953 to 1963. Until 1957 he used cylinders lined with refractory material and insulated with asbestos, and he used asbestos gloves for 6-8 years. He died 8.0 months after diagnosis.
  • In patient 1's lung tissue (one lobe), the asbestos body burden was 22,000 per gram of dry lung tissue (95% CI 16,000-30,000; detection limit 400). The asbestos fiber burden was below the detection limit of 380,000 per gram.
  • Patient 1's asbestos fiber burden was below the laboratory detection limit of 380,000 fibers per gram of dry lung tissue.
  • The authors stated that patient 1's asbestos body burden was significantly higher than the limit of 1,000 per gram of dry lung tissue recommended by the Helsinki Consensus Document, indicating past asbestos exposure with high probability.
  • Patient 2, a 61-year-old woman, helped her husband produce prostheses in his dental laboratory from 1961 to 1991 (classified as possible exposure). For this work the authors could document only indirect asbestos exposure. She had also lived from 1946 to 1964 with her father, a dental technician. She survived 4.3 years.
  • As a non-occupational exposure, patient 2 reported that at the end of the 1980s she held an asbestos-cement slab while her husband drilled holes in it to build a sound barrier.
  • Patient 3, a 79-year-old man, worked as a dental technician from 1952 to 1956 (classified as possible exposure) and survived 11.3 months.
  • Patient 4, a 70-year-old man, was a freelance dental technician from 1965 to 1999 (classified as definite exposure). He lined rings with asbestos twice a week for 10 years and died after 1.5 years.
  • None of the four patients knew which type of asbestos had been used.
  • Compensation claims were filed for all four patients. Only the first was compensated, because the others were self-employed or not formally employed and so were not covered by work insurance.
• The authors' conclusion: The authors concluded that they had documented two mesothelioma cases related to dental technician work with definite asbestos exposure and two with possible occupational asbestos exposure. They stated that dental technicians with mesothelioma should be questioned about past occupational asbestos exposure.
• Limitations the authors state:
  • Only one lung lobe was available for patient 1's asbestos body and fiber analysis, so the authors considered the analysis probably suboptimal.
  • Patient 3 gave a less detailed work history, so the authors inferred that the usual casting procedures could apply to him.
  • The authors knew of no data on asbestos concentrations in dental laboratories in Italy.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Malignant Mesothelioma, Occupational Exposure, Pleural Mesothelioma, Asbestos Exposure, Mesothelioma.

Related studies

• Exposure to methyl methacrylate and its subjective symptoms among dental technicians, Tehran, Iran — F. Golbabaei, M. Mamdouh, et al. (2005)
• Dental technician's pneumoconiosis. A report of two cases — P. De Vuyst, R. Vande Weyer, et al. (1986)
• Respiratory morbidity in a population of French dental technicians — S. Radi, J.C. Dalphin, et al. (2002)
• Occupational lung diseases among dental technicians — D. Choudat (1994)
• Malignant mesothelioma after exposure to asbestos in dental practice — A.S. Reid, B.E. Causton, et al. (1991)
• Malignant mesothelioma due to asbestos exposure in dental tape — S.B. Markowitz, J.M. Moline (2017)

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