Lung Cancer Risk in Male Dentists: A Retrospective Cohort Study in Japan, 1964–1997

Characterization of dental dust particles and their pathogenicity to respiratory system: a narrative review

OBJECTIVES

Dental professionals are exposed to large amounts of dust particles during routine treatment and denture processing. This article provides a narrative review to investigate the most prevalent dust-related respiratory diseases among dental professionals and to discuss the effects of dental dust on human respiratory health.

MATERIALS AND METHODS

A literature search was performed in PubMed/Medline, Web of Science, and Embase for articles published between 1990 and 2022. Any articles on the occupational respiratory health effects of dental dust were included.

RESULTS

The characterization and toxicity evaluation of dental dust show a correlation between dust exposure and respiratory system injury, and the possible pathogenic mechanism of dust is to cause lung injury and abnormal repair processes. The combination use of personal protective equipment and particle removal devices can effectively reduce the adverse health effects of dust exposure.

CONCLUSIONS

Dental dust should be considered an additional occupational hazard in dental practice. However, clinical data and scientific evidence on this topic are still scarce. Further research is required to quantify dust in the dental work environment and clarify its pathogenicity and potential toxicological pathways. Nonetheless, the prevention of dust exposure should become a consensus among dental practitioners.

CLINICAL RELEVANCE

This review provides dental practitioners with a comprehensive understanding and preventive advice on respiratory health problems associated with dust exposure.

Elemental analysis of contemporary dental materials regarding potential beryllium content

Exposure to beryllium (Be) can lead to lung pathologies, such as chronic beryllium disease (CBD). This occupational illness has been more prevalent among dental technicians compared to the non-exposed population. Although most manufacturers state that dental materials are Be-free, this prevalence raises the question of whether the materials are completely devoid of Be-traces. Thus, the objective of the present study was to analyze the elemental composition, with emphasis on Be, of a wide range of commercially available dental materials frequently used by dental laboratories. Samples of 32 different materials were collected and analyzed using inductively coupled plasma-optical emission spectrometry (ICP-OES) and X-ray fluorescence spectroscopy. The results showed that the Be content was below the limit of quantification in all included samples (< 0.00005 mass-%). Therefore, it can be concluded that possible traces of Be were below clinical relevance in dental materials. Exposure of dental technicians to alternative Be sources should be further evaluated.

Potential airborne asbestos exposures in dentistry: a comprehensive review and risk assessment

Chrysotile was formerly used in the manufacture of casting ring liner (CRL) and periodontal dressing powder (PDP). The purpose of this study was to describe the potential for airborne asbestos exposure among dental professionals who may have used these products and to assess their risk of asbestos-related disease (ARD). Task-specific exposure data associated with CRL and PDP were identified and compared to regulatory standards for asbestos and health-based benchmarks. Personal airborne fiber concentrations ranged from 0.008-3.5 f/cc by PCM (duration: 3-420 minutes) for CRL (tearing, placement), and from <0.0044-<0.297 f/cc by PCM (duration: 5-28 minutes) for PDP (mixing). Eight-hour time-weighted average (TWA) exposures were calculated using the reported task-based airborne fiber concentrations and associated sampling durations. For CRL tasks, the upper-bound calculated 8-hour TWA of 0.022 f/cc (tearing, placement) did not exceed regulatory standards for asbestos (≥0.1 f/cc). All samples collected during the mixing of PDP resulted in non-measurable fiber concentrations. The greatest estimated cumulative asbestos exposure for dental professionals using CRL (tearing, placement) of 0.33 f/cc-years is well below "best estimate", published chrysotile no-observed-adverse-effect-levels (NOAEL) for ARD (lung cancer = 89-168 f/cc-years; pleural mesothelioma = 208-415 f/cc-years). As such, the use of asbestos-containing CRL and/or PDP is not expected to pose an increased risk of ARD among dental professionals. This conclusion is consistent with the lack of an increased risk of ARD reported in epidemiological studies of these occupations.

Cancer mortality among Brazilian dentists

BACKGROUND

Previous studies have variably shown excess risks of elected cancers among dentists.

METHODS

National Brazilian mortality data were used to obtain mortality patterns among dentists between 1996 and 2004. Cancer mortality odds ratios (MORs) and cancer proportional mortality ratios for all cancer sites were calculated, using the general population and physicians and lawyers as comparison groups.

RESULTS

Female dentists from both age strata showed higher risks for breast, colon-rectum, lung, brain, and non-Hodgkin lymphoma. Compared to physicians and lawyers, higher MOR estimates were observed for brain cancer among female dentists 20-49 yr. Among male dentists, higher cancer mortality was found for colon-rectum, pancreas, lung, melanoma, and non-Hodgkin lymphoma. Higher risk estimates for liver, prostate, bladder, brain, multiple myeloma and leukemia were observed among 50-79 yr old male dentists.

DISCUSSION

If confirmed, these results indicate the need for limiting occupational exposures among dentists in addition to establishing screening programs to achieve early detection of selected malignant tumors.

Outpatient visits by dentists: a nationwide cohort study in Taiwan

We conducted a cohort study of 7,760 dentists in Taiwan between 2003 and 2007 to assess the risk of outpatient visit among dentists. Control groups included physicians and other health personnel. Over the 5-yr study period, the dentist cohort made a total of 270,712 outpatient visits, representing an incidence rate of 7,038 visits /10(3) person-years. Compared to physicians, dentists experienced a significantly reduced covariate adjusted rate ratio (ARR) for all-cause visits (ARR=0.59, 95%CI=0.58-0.59), as well as for nearly all other causes, except neoplasm (ARR=1.06, 95%CI=1.02-1.09). Compared to other health personnel, the dentists still experienced a significantly reduced ARR for all causes (ARR=0.70), but had a slightly but significantly increased risk for endocrine/metabolic/immunity (ARR=1.04, 95%CI=1.02-1.05) and mental (ARR=1.04, 95%CI=1.01-1.07) disorders. Although the dentists in Taiwan utilized lesser outpatient visits than did their medical colleagues, they tended to have slightly higher rates of outpatient visits for neoplasm, endocrine/metabolic/immunity disorders, and mental illnesses. Policy makers and hospital administrators must not overlook dentists' potentially unseen health problems. A mandatory periodical physical examination for dentists can seriously be considered.

Autopsy cases of lung cancer and liver cancer among Japanese dentists--a review of the annual of the pathological autopsy cases in Japan

Dentists are exposed to carcinogenic metals during their work. It has been speculated that dentists are also at high risk for occupational exposure to bloodborne viruses such as hepatitis B and hepatitis C. We suspected that Japanese dentists were at increased risk for lung and liver cancer. To assess this question, we compared the number of pathological diagnoses of lung cancer and liver cancer among autopsy cases of male dentists (n=225) with that among autopsy cases of male medical doctors (n=1,296), based on data from the Annual of the Pathological Autopsy Cases in Japan from 1992 to 1999. We calculated the mortality odds ratio of lung cancer and liver cancer, using stomach cancer as the control. No difference between the dentist group and the medical doctor group was observed in the pathological diagnoses of lung cancer among all autopsy cases (p=0.703, Odds Ratio: 0.846, 95% confidence interval: 0.461-1.554). Liver cancer was observed less often among dentists than among medical doctors (p=0.047, Odds Ratio: 0.474, 95% confidence interval: 0.239-0.941). Based on the results of this study, we suggest that Japanese male dentists do not have a higher risk of developing lung cancer than male medical doctors, and have a lower risk of developing liver cancer.

Literature review of cancer mortality and incidence among dentists

This review assesses the epidemiological literature describing dentist mortality and cancer incidence risk. In the dental workplace a variety of hazards may have been historically present or currently exist which can impact dentists' long-term health, including their mortality and cancer incidence. The epidemiological literature of dentistry's health outcomes was reviewed with a focus on all cancers combined and cancers of the brain, lung, reproductive organs and skin. Relevant studies were identified using MEDLINE and NIOSHTIC through early 2006 and from references cited in the articles obtained from these databases. Dentist cancer mortality and incidence generally showed a favourable risk pattern for lung cancer and overall cancer occurrence. Nevertheless, several studies reported an increased risk for certain cancers, such as those of the skin and, to a lesser extent, the brain and female breast. These elevated risks may be related to social status or education level, or may alternatively represent the impact of hazards in the workplace. The evidence for an increased mortality or cancer incidence risk among dentists must be interpreted in light of methodological limitations of published studies. Future studies of dentists would benefit from the assessment of specific occupational exposures rather than relying on job title alone.

Liver Cancer Risk in Japanese Male Dentists: A Long‐Term Retrospective Cohort Study

It has been speculated that dentists are at high risk for occupational exposure to bloodborne viruses such as hepatitis B and hepatitis C viruses. To assess the risk of the development of liver cancer among Japanese male dentists, we conducted a retrospective cohort study on 3,314 dentists of the Osaka Dental Association who were members between 1964 and 1985, the year before HBV immunization became available. By linking to the Osaka Cancer Registry, we found that during the period of 1964-1997, 36 of the dentists were diagnosed with liver cancer over a mean follow-up of 23.6 yr. The observed number of liver cancer cases was compared with the expected number, which was calculated by multiplying the number of person-years at risk by the corresponding age- and calendar time-specific incidence rate from the Osaka Cancer Registry data. The male dentists had a significantly lower risk of developing liver cancer than the general population of Osaka (O/E=0.71, 95% CI=0.50-0.98). On subcategorical analysis by birth year or duration of follow-up, there was no significantly increased risk of developing liver cancer among the dentists. Contrary to our expectation, our findings indicate that Japanese dentists were not at increased risk of developing liver cancer compared with the general population.