Pneumoconiosis and respiratory problems in dental laboratory technicians: analysis of 893 dental technicians

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.

Co-occurrence of pneumoconiosis with COPD, pneumonia and lung cancer

BACKGROUND

Pneumoconiosis is a well-documented occupational disease that is linked to conditions such as chronic obstructive pulmonary disease (COPD), pneumonia and congestive heart failure. Pneumoconiosis prevalence has decreased in the United States, but it remains implicated in tens of thousands of deaths worldwide per year.

AIMS

To provide a recent update on associations of pneumoconiosis and smoking status with various pulmonary diseases in the United States.

METHODS

The CDC's National Vital Statistics System was analysed on the entity axis using ICD-10 codes for pulmonary disease and potential lung injury with a cohort of those aged 15 and older during the years 2010-2019. The cases of evaluated diseases were scaled to rates per 100 000 and compared through analysis of variance.

RESULTS

Pneumoconiosis and smoking history were each associated with an increased rate of COPD, but combined, were associated with an even higher rate of COPD than either factor alone. Smoking history was associated with an increased rate of lung cancer, but pneumoconiosis status was only linked to increased lung cancer prevalence in non-smokers. Both pneumoconiosis and smoking were associated with an increased rate of pneumonia, but combined, had no deviation from the pneumonia rate in those with pneumoconiosis alone. Finally, pneumoconiosis status was associated with decreased rates of non-lung cancers and sepsis.

CONCLUSIONS

Although pneumoconiosis has become less common in the United States through regulatory and industrial shifts, it is still a significant risk factor for co-occurring pulmonary diseases and will likely remain relevant as international demands for mining, construction and manufacturing change.

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.

Pitfalls of using the ILO classification for silicosis compensation claims

BACKGROUND

The International Labour Organization (ILO) Classification of Radiographs of Pneumoconioses is used as the primary tool to determine compensation for pneumoconiosis in Turkey.

AIMS

We aimed to evaluate how the ILO classification applied, but obtaining chest radiographs in the workplace for screening until the completion of compensation claim files by the referral centres, based on the ILO reading.

METHODS

The study included 320 digital chest radiographs previously taken for screening from eight different ceramic factories and having finalised claim files by referral centres. We used an expert reference panel consisting of five ILO readers to re-evaluate all the radiographs independently using ILO standard films and reached a conclusion based on the agreement among at least three readers. The evaluation primarily included technical quality and silicosis diagnosis with an ILO 1/0 or above small profusion. The results were compared with previous findings.

RESULTS

Sixty-three (20%) chest radiographs were unacceptable for classification purposes according to the ILO technical quality grades. Among the remaining 257 chest radiographs, we diagnosed 103 with silicosis (40%), while the referral centres diagnosed 182 (71%). A discrepancy was found between our results and previous evaluations. We diagnosed silicosis in 50% and 17% of the previous silicosis and normal evaluations, respectively.

CONCLUSIONS

Our findings suggest that the use of the ILO classification for compensation claims may be problematic due to the way of its implementation in Turkey in addition to its subjectivity.

Acceptance and experience of digital dental technology, burnout, job satisfaction, and turnover intention for Taiwanese dental technicians

BACKGROUND

Digital dental technology (DDT) has progressed and been introduced to Taiwan in the recent years, gradually changing the industry ecology. Many studies have demonstrated that DDT is more accurate and faster than conventional dental technology. However, there is a paucity of research exploring dental technicians' perspectives on digital dental techniques, and their burnout, job satisfaction, and turnover intention.

METHODS

This cross-sectional survey with convenience sampling was conducted at the conference venue of the Taiwan Association of Dental Technology to investigate the perspectives of dental technicians. We used the snowballing method in this study; two sampling methods were adopted, a convenience sampling of dental technicians to complete a survey, followed by asking the survey participants of the convenience sample to invite their colleagues to participate in the online survey. The survey questionnaire included questions on demographics, work-related information, acceptance and experiences of dental technicians toward DDT, occupational burnout, job satisfaction, and turnover intention. Regression models were used to determine the predictors of job satisfaction and determinants of turnover intention.

RESULTS

In total, 341 valid questionnaires were obtained. Overall, the participants reported long working hours (95.5%), positive score on the DDT acceptance scale, moderate job satisfaction, higher personal burnout, and work burnout, along with lower over-commitment. Among them, 32.9% and 28.2% reported the intention to leave their organization and profession, respectively. The stepwise multiple regression model revealed that higher work burnout decreased job satisfaction, while higher DDT acceptance and position as employer increased job satisfaction. The binary logistic regression models revealed that geographical area of workplace, work burnout, and job satisfaction were significant predictors of turnover intentions.

CONCLUSIONS

Many Taiwanese dental technicians reported turnover intentions and higher burnout. With the trend of digitalization in the dental industry, even though most dental technicians had a positive outlook toward DDT, its influence on job satisfaction appears limited. Retaining good and professional talents required of a dental technician is crucial, especially as Taiwan's dental care becomes increasingly specialized. Strategies for improving the work environment and occupational health of dental technicians should thus be the focus of future studies.

Efficacy of dental evacuation systems for aerosol exposure mitigation in dental clinic settings

Dental personnel are ranked among the highest risk occupations for exposure to SARS-CoV-2 due to their close proximity to the patient's mouth and many aerosol generating procedures encountered in dental practice. One method to reduce aerosols in dental settings is the use of intraoral evacuation systems. Intraoral evacuation systems are placed directly into a patient's mouth and maintain a dry field during procedures by capturing liquid and aerosols. Although multiple intraoral dental evacuation systems are commercially available, the efficacy of these systems is not well understood. The objectives of this study were to evaluate the efficacy of four dental evacuation systems at mitigating aerosol exposures during simulated ultrasonic scaling and crown preparation procedures. We conducted real-time respirable (PM4) and thoracic (PM10) aerosol sampling during ultrasonic scaling and crown preparation procedures while using four commercially available evacuation systems: a high-volume evacuator (HVE) and three alternative intraoral systems (A, B, C). Four trials were conducted for each system. Respirable and thoracic mass concentrations were measured during procedures at three locations including (1) near the breathing zone (BZ) of the dentist, (2) edge of the dental operatory room approximately 0.9 m away from the mannequin mouth, and (3) hallway supply cabinet located approximately 1.5 m away from the mannequin mouth. Respirable and thoracic mass concentrations measured during each procedure were compared with background concentrations measured in each respective location. Use of System A or HVE reduced thoracic (System A) and respirable (HVE) mass concentrations near the dentist's BZ to median background concentrations most often during the ultrasonic scaling procedure. During the crown preparation, use of System B or HVE reduced thoracic (System B) and respirable (HVE or System B) near the dentist's BZ to median background concentrations most often. Although some differences in efficacy were noted during each procedure and aerosol size fraction, the difference in median mass concentrations among evacuation systems was minimal, ranging from 0.01 to 1.48 µg/m3 across both procedures and aerosol size fractions.

Mixed-dust pneumoconiosis in a dental technician: a multidisciplinary diagnosis case report

BACKGROUND

In dental laboratories, exposure to crystalline silica can occur during procedures that generate suspended mineral dusts, e.g. dispersion of mixing powders, removal of castings from molds grinding, polishing of castings and porcelain, and use of silica sand for blasting. There is also a large list of toxic agents (acrylic resins, polymeric materials, etc.) used to produce removable and fixed prostheses, but also impression materials and more. Using personal protective equipment and other aids reduces the exposure to these potentially harmful agents.

CASE PRESENTATION

We report the case of a 42-year-old male dental technician who began to suffer from a dry cough and exertional dyspnea after approximately 15 years of work. The operations he conducted for his job resulted in the generation of crystalline silica, aluminum, chromium and titanium dust. The worker did not regularly wear personal protective equipment and some of the above operations were not carried out in closed circuit systems. The Chest X-ray showed diffused micronodules in the pulmonary interstitium of the upper-middle lobes, bilaterally, and a modest left basal pleural effusion. Simple spirometry showed small airway obstruction in its initial stage. High Resolution Computerized Tomography of the chest showed bilateral micronodulation of a miliariform type, with greater profusion to the upper lobes, also present in the visceral pleura, bilaterally. Histological examination showed aggregates of pigment-laden macrophages forming perivascular macules or arranged in a radial pattern around a core of sclerohyalinosis. Scanning Electron Microscopy and Energy Dispersive Spectrometry revealed several mineral particles, typically characterized by the presence of crystalline silica and metal aggregates. The environmental concentrations of total dust and its respirable fraction were all lower than the relative TLV-TWA-ACGIH, yet not negligible.

CONCLUSIONS

The above findings and a multidisciplinary assessment led to the diagnosis of mixed dust pneumoconiosis s/q with 2/2 profusion of occupational origin. This diagnosis in a dental technician was supported for the first time in literature by environmental exposure analysis.

Early signs of pneumoconiosis in a dental technician in Italy: a case report

BACKGROUND

Dental technicians are at high risk of pneumoconiosis, usually driven by inhalation of mixed dusts, including metals. An etiological diagnosis is not easy to be performed, particularly in advanced stages.

CASE PRESENTATION

We describe the case of an early pneumoconiosis occurring in a 47-year-old dental technician who developed respiratory symptoms shortly after beginning work. She described the work environment as dusty and lacking relevant primary prevention tools. A chest CT showed multiple peripheral pseudonodular lesions in both lower lobes; bronchoalveolar lavage and bronchial aspirate evidenced numerous macrophages with reflective metal bodies included into the cytoplasm, that at scanning electron microscopy coupled to Energy Dispersive X-Ray Analysis resulted Zirconium and Aluminum, whereas Tungsten (W) was localized outside cells. End of shift urinary concentrations of W were substantially raised as compared to pre-shift (1.1 vs. 0.2 µg/L).

CONCLUSIONS

We concluded for diagnosis of early work-related pneumoconiosis due to abnormal occupational exposure to metals. The case demonstrates the need also for dental professionals to comply with industrial hygiene standards and to be monitored by occupational health physicians.

Assessment of occupational exposure to fine particulate matter in dental prosthesis laboratories in Kocaeli, Turkey

Dental prosthesis laboratories (DPLs) are among the workplaces where predominantly manual production takes place. In such working environments, during the manual manufacturing process, which involves fine smoothing and polishing of dental prostheses, fine particulate matter is released into the ambient air. In this study, the particulate matter (PM) concentrations and elemental content of the fine particles in the working ambient air were identified in six DPLs in Kocaeli, Turkey. PM_2.5 mass concentrations, measured in all the DPLs, ranged between 80.8 and 1645 μg/m³ (mean 414 ± 406). As a result of the analyses performed with an ICP-MS device (Perkin Elmer Elan®DRC-e), trace elements of Be, Cd, Hg, and, notably, Co, Cr, Mo, and Ni were found. The researchers calculated the excess lifetime cancer risks and total hazard indexes. The average total cancer risk for all the DPLs was 8 × 10^-3, which is higher than the acceptable limit of 1.0 × 10^-6, and the total hazard index was 187, which is greater than the acceptable limit of 1.0. Considering these high-level risks, the study concluded that there is a need for new production methods, and strict application of occupational health and safety measures, to reduce the fine particle exposure of the workers in the laboratories. In addition, there are prescribed limit values for particulate matter only for respirable particles in working environments. The establishment of limit values, especially for PM_2.5 concentrations, is important for the protection of the health of the employees.

Pulmonary Alterations Among Workers in a Dental Prosthesis Laboratory: Exploring High Dust Concentrations and Novel Findings of Bacterial Genera in the Workplace to Achieve Improved Control

OBJECTIVE

To evaluate the pulmonary alterations in workers from a dental prosthesis laboratory and explore dust and bacterial dissemination generated in the laboratory.

METHODS

Spirometry and computerized axial tomography were performed on 67 workers. Dust in workplace air was determined using the filtration-gravimetric method, and bacterial detection was explored using 16S rDNA gene sequencing.

RESULTS

Pulmonary alterations were detected in 37% of the workers. Airborne dust concentrations were determined to be higher than the maximum permissible exposure limit, and bacterial detection analysis revealed 23 bacterial genera. The most frequently detected bacterial genus was Sphingomonas sp., which has been described as microbiota associated with disease of the oral cavity.

CONCLUSIONS

The results of this study highlight the importance of the implementation of biosecurity measures, improvement of ventilation systems, and routine disinfection of dental impressions.

P2Y12 Receptor Antagonist Clopidogrel Attenuates Lung Inflammation Triggered by Silica Particles

Silicosis is an occupational lung disease caused by inhalation of silica particles. It is characterized by intense lung inflammation, with progressive and irreversible fibrosis, leading to impaired lung function. Purinergic signaling modulates silica-induced lung inflammation and fibrosis through P2X7 receptor. In the present study, we investigate the role of P2Y12, the G-protein-coupled subfamily prototype of P2 receptor class in silicosis. To that end, BALB/c mice received an intratracheal injection of PBS or silica particles (20 mg), without or with P2Y12 receptor blockade by clopidogrel (20 mg/kg body weight by gavage every 48 h) - groups CTRL, SIL, and SIL + Clopi, respectively. After 14 days, lung mechanics were determined by the end-inflation occlusion method. Lung histology was analyzed, and lung parenchyma production of nitric oxide and cytokines (IL-1β, IL-6, TNF-α, and TGF-β) were determined. Silica injection reduced animal survival and increased all lung mechanical parameters in relation to CTRL, followed by diffuse lung parenchyma inflammation, increased neutrophil infiltration, collagen deposition and increased pro-inflammatory and pro-fibrogenic cytokine secretion, as well as increased nitrite production. Clopidogrel treatment prevented silica-induced changes in lung function, and significantly reduced lung inflammation, fibrosis, as well as cytokine and nitrite production. These data suggest that inhibition of P2Y12 signaling improves silica-induced lung inflammation, preventing lung functional changes and mortality. Our results corroborate previous observations of silica-induced lung changes and expand the understanding of purinergic signaling in this process.

Epidemiology of silicosis: reports from the SWORD scheme in the UK from 1996 to 2017

OBJECTIVE

To document the demographic risk factors of workers reported to have silicosis in the UK.

METHODS

All cases of silicosis reported to the Surveillance of Work-related and Occupational Respiratory Disease (SWORD) scheme between January 1996 and December 2017 were classified into one of eight industry categories, and one of five age groups. In addition, to investigate whether there had been any temporal change, mean age and range at diagnosis was plotted for each year. From 2006, data were also available relating to the date of onset of symptoms, allowing a comparison between workers with and without respiratory symptoms.

RESULTS

For the period between 1996 and 2017, there were 216 cases of silicosis reported. The mean (range) age of those reported was 61 years (23-89), with the majority (98%) being male. Across all industries, 65% of cases were diagnosed in individuals of working age (<65 for men and <60 for women). Silicosis was reported in young workers across all industry groups, with around one in six of all silicosis cases affecting workers under the age of 46 years. There was no clear trend in age of diagnosis with time. Between 2006 and 2017, 81% of 108 workers with silicosis were reported to be symptomatic.

CONCLUSIONS

Silicosis remains an important health problem in the UK affecting workers of all ages across a wide range of industries traditionally associated with silica exposure.

Silicosis: A former occupational disease with new occupational exposure scenarios

BACKGROUND

Recent studies have shown an increase in the prevalence of silicosis due to the use of artificial quartz aggregates (AQA). The aim of this study was to assess the cases of silicosis in our area reported to the Healthcare Information System for Occupational Epidemiological Surveillance of the Autonomous Community of Valencia to detect new agents of exposure to silica and working conditions that promote its onset.

MATERIAL AND METHOD

A descriptive study was conducted of cases of silicosis reported to the Healthcare Information System for Occupational Epidemiological Surveillance of the Autonomous Community of Valencia from January 2009 to September 2016. The data sources include epidemiological-occupational surveys and medical reports.

RESULTS

Nineteen cases of silicosis were reported, 74% of which were diagnosed using high-resolution computed tomography. Some 68.4% of the cases were related to the handling of AQA, as assemblers/cutters/sanders of countertops. The subgroup's mean age was 46.62±13.33 years, and the mean exposure was 11.00±3.58 years. The rest of the patients worked in companies with no AQA exposure, with a mean age of 62.33±16.22 years and a mean exposure of 27.16±8.44 years (P<.05). Four cases presented complicated forms (3 exposed to AQA).

CONCLUSIONS

The work of assembling/cutting/sanding AQA countertops presents a high risk of developing the disease. The mean age at onset and the exposure time for this group is lower, and the percentage of complicated clinical forms is higher. Improvements need to be made in preventive planning for companies with exposure to these new agents.

Silicosis in Turkey: Is it an Endless Nightmare or is There Still Hope?

Silicosis is an ancient but still life-threatening occupational lung disease because of its incurable nature. Although its risks are known in many occupational settings and effective control strategies are well established, new cases, even epidemics, continue to occur in different sectors of Turkey. Before taking action, defining the magnitude of the problem is essential. In this concise review, we aimed to present the current situation of silicosis in Turkey. According to the data available to date, silicosis continues to be a major health problem in different sectors. Sandblasting seems to have the highest risk for the development of silicosis. Disease onset at early age and history of short exposure duration may indicate intense silica exposure. After denim sandblasters, dental technicians seem to be the new and recently recognized high-risk occupation group as per the increasing reports. Because of the lack of a definite treatment of silicosis, prevention of the disease should be the main target. Better occupational disease registry systems would be useful to assess the magnitude of the problem. In addition to implementing the necessary regulations, a close inspection of the workplaces for potential risks is essential. Other social and economic factors related with the occurrence of disease, such as unregistered employment rate and unlicensed and uninsured work, should also be considered. Finally, optimal healthcare and better living conditions for patients with silicosis should be ensured.

Dental Technicians' Pneumoconiosis

A 40-year-old female dental technician visited our hospital for the investigation of a chest X-ray abnormality. Chest computed tomography demonstrated centrilobular nodules and lung volume reduction, and her serum KL-6 level was elevated. A histological analysis of the specimens obtained on a surgical lung biopsy showed peribronchiolar fibrosis with pigmented macrophages and cholesterol clefts. An energy-dispersive X-ray analysis showed that these lung tissues contained some metals, including indium. The serum indium level was also elevated. We diagnosed this patient with pneumoconiosis caused by exposure to sandblasting certain dental metals. This is the first reported case of pneumoconiosis in a dental technician associated with exposure to indium.

Evaluation of Dynamic Disulphide/Thiol Homeostasis in Silica Exposed Workers

BACKGROUND

Oxidative stress is implicated as one of the main molecular mechanism underlying silicosis.

AIMS

In this study, our aim was to asses the redox status in occupationally silica-exposed workers, by evaluating the dynamic thiol-disulphide homeostasis.

STUDY DESIGN

Case-control study.

METHODS

Thirty-six male workers occupationally exposed to silica particles and 30 healthy volunteers, working as office workers were included to the study. Posteroanterior chest radiographs and pulmonary function tests of both groups were evaluated. Also serum thiol disulphide levels were measured using the spectrophotometric method described by Erel and Neşelioğlu.

RESULTS

Among the 36 workers that underwent pulmonary function tests 6 (17%) had obstructive, 7 (19%) had restrictive, 6 (17%) had obstructive and restrictive signs whereas 17 (47%) had no signs. The mean PFTs results of silica-exposed workers were significantly lower than control subjects. The serum disulphide levels of silica-exposed workers were significantly higher than control subjects (23.84±5.89 μmol/L and 21.18±3.44 μmol/L, respectively p=0.02).

CONCLUSION

The serum disulphide levels, a biomarker of oxidative stress, are found to be higher in silica-exposed workers.

Respiratory Systems of Dental Technicians Negatively Affected during 5 Years of Follow-Up

BACKGROUND

Dental laboratory technician is one of the professions in which dust exposure is frequently experienced and therefore the health of workers has to be monitored.

AIMS

In this study, changes in the pulmonary functions and of pneumoconiosis frequencies among dental technicians after five years were investigated by comparing the results of two screenings carried out in 2008 and 2013.

STUDY DESIGN

Cohort study.

METHODS

In 2008 and 2013, Provincial Health Directorate carried out two different health screenings covering all of the dental technicians working in dental laboratories in Denizli. In both screenings, a questionnaire was applied, with which socio-demographic and workplace properties of the technicians were obtained. In addition, Pulmonary function tests (PFT) and standard chest X-rays of the technicians were performed. The results of these two screenings were evaluated by a chest specialist, and physical examinations were performed as necessary. In 2013, technicians who had pathologies underwent computerized tomography (HRCT). In this study, the study group was composed of dental laboratory technicians that participated in both screenings (2008 and 2013) and the data obtained from the screenings were compared. The gathered data were analyzed using paired student-t and X(2) tests.

RESULTS

A total of 125 dental laboratory technicians participated in the two screenings. Overall, 92% of the technicians were male and the mean age of the participants was 35. Technicians were working for 9 hours a day, 6 days a week. Total exposure time was calculated to be around 41 thousand hours. Approximately 60% of workers were smokers. When the results of PFT were analyzed, 73% of the first evaluations were found to be normal; however, this ratio decreased to 51% in the second analysis five years later. In the second PFT measurement, compared to the first, there was a 23% decrease in the forced vital capacity (FVC) value, and a 15.7% decrease in forced expiratory volume in one second (FEV1). While restrictive disorder was found 25% in the first PFT evaluations, this ratio increased to 31% in the second PFT. When the radiological results were considered, 62% of the first X-ray results were found to be normal but this ratio decreased to 18% in 2013. While reticular/reticulonodular opacities were found in 11% of cases in 2008, it increased to 30% in 2013. Seven technicians were diagnosed with pneumoconiosis (5.6%).

CONCLUSION

Respiratory tracts of the technicians were negatively affected during the five year period. The number of pneumoconiosis cases (5.6%) shows that it is necessary to adopt comprehensive work health and safety precautions for laboratories.

Dental technician pneumoconiosis mimicking pulmonary tuberculosis: a case report

Background

Dental laboratory technicians are at risk of developing occupational respiratory diseases due to exposure to various potentially toxic substances in their working environment. Since 1939, few cases of silicosis among dental technician have been reported.

Case presentation

We illustrate a 38 year-old female, who worked in a dental laboratory for 20 years, initially treated as pulmonary tuberculosis and chronic necrotising aspergillosis without much improvement. Computed tomography guided lung biopsy and bronchoscopic transbronchial lung biopsy were performed. Lung tissue biopsies showed presence of refractile dental materials within the areas of histiocyte proliferation. The diagnosis of dental technician pneumoconiosis was obtained and our patient underwent pulmonary rehabilitation.

Conclusions

This case highlights the importance of obtaining a detailed occupational history in tuberculosis endemic area, as pulmonary tuberculosis is a great mimicker of other respiratory diseases.