Froudarakis ME, et al. The results showed that the three types of grinding dust had entirely different morphologies. In this study, high-speed grinding was used to test the hypothesis that ultrafine particles do not form a substantial component of mechanically generated aerosols. The effects of dust on macrophages via the classical (type 1 helper T cell factor involvement) and selective activation (type 2 helper T cell factor involvement) pathways31. HHS Vulnerability Disclosure, Help Some discrepancy was observed in the overlap region between the APS and the SMPS/LDMA. Radi S, et al. Respiratory symptoms, lung function, and pneumoconiosis among self employed dental technicians. B13003). government site. As shown in Fig. Received 2019 Dec 19; Accepted 2020 Aug 17. Particle size distribution of the three dental prosthetic grinding dust particles before and after fine milling. region: "", Also, micrographs from the steel substrate showed the existence of nanometer size primary particles within large open agglomerates. The distribution of particle size was measured by a particulate size description analyser (PSDA; Mastersizer Macro, Malvern, United Kingdom). The difference between the three dust samples and the negative control group was statistically significant (P<0.05). Seldn AI, et al. In particular, the changed in nuclear location was more pronounced in the cells exposed to the porcelain dust. Notice, Smithsonian Terms of Three types of dental prosthesis grinding dust particles, PMMA dust, Vitallium dust, and dentin porcelain dust, were all toxic to RAW264.7 cells. ANTHONY T. ZIMMER, ANDREW D. MAYNARD, Investigation of the Aerosols Produced by a High-speed, Hand-held Grinder Using Various Substrates, The Annals of Occupational Hygiene, Volume 46, Issue 8, September 2002, Pages 663672, https://doi.org/10.1093/annhyg/mef089. 5. This finding was consistent with the results of the present study. Dental prostheses are made and tested, a variety of dust particles are emitted from the grinding performed to correct defects14. In this study, the morphologies, particle size distributions, and compositions of the three types of dental prosthesis grinding dust were measured. There was no significant difference between the PMMA group and the Vitallium group, and the porcelain group was significantly different from both other groups (P<0.05). Transmission electron microscope micrographs of the various grinding substrates including: (a) granite, (b) clay ceramic, (c) steel, (d) aluminum and (e) PTFE. Everything is made much larger so you can visually see the comparison. Zhang et al. Due to the assumption that the aerosols generated from these processes mainly result from mechanical attrition of the substrate, prior research to characterize the particle size distribution has focused upon the micrometer size regime using techniques such as cascade impaction (Lehmann and Frohlich, 1988; Kusaka et al., 1992). Compared with the control group at different time points, the cell survival rate of the exposed cells gradually decreased. Meng C, et al.
reported that animals were subjected to mixed dust types generated from grinding dental prostheses (PMMA, Vitallium and porcelain dust, etc. The large amount of ROS can produce cell lipid peroxidation, which damages normal cells and tissues18. In presenting number statistics for the ultrafine mode, the data obtained by the SMPS/NDMA were used for fitting the left-hand side of this mode as this instrument was optimized to sample aerosols in the particle size range 10100 nm. The cells were incubated in 5% CO2 at 37C for 6, 12, 24, and 48h. However, the incubation times were only 24h and 48h for the LDH analysis. For a better understanding of the source of the ultrafine mode arising from grinding on these substrates, the use of alternative sample collection methods or analytical methods such as electron energy loss spectroscopy (EELS) should be considered for future research (Brydson, 2000; Maynard, 2000). (2001) have shown that the number-weighted aerosol size distribution generated while grinding beryllium ceramic is dominated by particles <100 nm and Choe et al. Yang et al. Grinding of the steel substrate led to a distinct difference between the results obtained in the overlap region between the SMPS/LDMA and the APS. SMPS/NDMA, SMPS/LDMA and APS) was started 60 s after the grinding burst. In presenting number statistics for the coarse mode, the data obtained by the APS were fitted using the right-hand side of this mode. The possible mechanism of toxicity may relate to the manner in which the dust entered the cell and its production of lipid peroxidation, which damaged the cell membrane and other structures. All three types of fine dental prosthesis grinding dust led to ROS increases in the macrophages in a time-dependent manner. It was also evaluated with LDH and ROS assays. Cell viability rate of 300gmLl of different types of dental prosthesis grinding dust particles on RAW264.7 cells after 24h of exposure. TEM images were characterized by large numbers of compact particles >1m, with some evidence for abraded particles <<1m (Fig. After fine milling, only the particle sizes were reduced, but their shapes did not significantly change. To ensure that there was little temporal variation over the time scales needed to collect aerosol samples, a CPC was used to characterize the temporal variation of the total number concentration during a grinding sample run. Grinding typically occurs on a wide variety of substrates. Yang CJ, et al. The rotational speed of the grinding wheel was determined using a tachometer (Dynapar model HT50; Danaher Controls, Gurnee, IL). The cells were stained by fluorescent dye by adding 1ml of 95 v/v % alcohol to each well and, 30min later, followed by the addition of 0.1mgmll acridine orange and incubation for 15min in the dark at room temperature. Each point in the figures represents the arithmetic mean of the triplicate random samples while the bars estimate the standard error associated with each particle size class. At 6h, the number of viable exposed cells was reduced, but the change was not significant (P>0.05). In addition, the multiple comparison analysis based on LSD showed that the effect of the porcelain dust group was higher than the PMMA group and the Vitallium group, and the difference was statistically significant (P<0.05). Zhou H, et al. Research advances in silicon pulmonary fibrosis. 4. 4). Larger, nanometer scale particles (60.4 nm < dp < 777 nm) were characterized using a SMPS configured with a long DMA (DMA model 3934 and a condensation particle counter model 3022A; TSI Inc.). Validation of the Portuguese version of the Functional Index for Hand Osteoarthritis (FIHOA). Grinding of the dust samples was performed using a shatter box. Zhang ZY, et al. 2d. reported that macrophages produce ROS after engulfing dust particles17. 
In many cases the measured size distributions exhibited multi-modal behavior. Grinding of PTFE was the main exception; this produced large numbers of nanometer diameter, nearly spherical particles that were almost certainly PTFE. 
A wide variety of grinding substrates were selected for evaluation to represent the broad spectrum of materials available. The high density particles produced from the steel substrate ( 7.9 kg/m3), together with uncertainty over their morphology, are probably responsible for the poor transformation between aerodynamic diameter and equivalent-sphere projected area diameter with the APS data. When viewing all of the substrates together for particle diameters corresponding to the ultrafine mode, it can be seen that, with the exception of wood, the size distributions generated by grinding were qualitatively similar to that produced using the grinding tool alone (Fig. Assessing the in vitro toxicity of the lunar dust environment using respiratory cells exposed to Al(2)O(3) or SiO(2) fine dust particles. 1, PMMA dust (g) contained mainly C and O, Vitallium dust (h) was composed mostly of Cr, Co, and Mo, and porcelain dust (i) consisted principally of Si, Al, and O. Andreyev AY, et al. In the absence of a substrate, there was also evidence that the grinding tool led to the formation of ultrafine particles, albeit at a much lower concentration. were responsible for the cell culture and contributed to the writing of the manuscript, X.L. Dust is one of the most common natural resources of aerosol particles in the atmosphere. The effect of these dust particles at different concentrations on RAW264.7 cells was evaluated. Vitallium (h), porcelain (i). Experimental study on pulmonary fibrosis caused by oral denture grinding with mixed dust. hair human air particulate matter pm particles compared albany study end south community dec gov ny Effects of 300gmLl of the different types of dental prosthesis grinding dust particles on RAW264.7 after 24h of exposure: PMMA (a), Vitallium (c), porcelain (e), and the negative control (g); after 48h, PMMA (b), Vitallium (d), porcelain (f), and the negative control (h). During dust storms, we are exposed to a high concentration of dust particles. Other substrates, such as wood dusts and metals, can be evaluated and compared with specific exposure criteria. PMMA, Vitallium, and porcelain test modules were prepared as per clinical procedures. 3. })}); ideal for capturing the similarly sized dust particles, How An Outdoor Cooling Mist System Can Create Safer Events, DustBoss Offers Dynamic Dust Control Solution with DB-60 Surge, Odor Control Misting Systems for Soil Remediation, Innovative Dust Suppression Methods for the Scrap Recycling Industry, Dust Suppression Helps Demolition Expert Protect Workers and Surrounding Community from Hazardous Emissions. Search for other works by this author on: Elevated COVID-19 Case Rates of Government Employees, District of Columbia, 20202022, Evaluation of Face Shields, Goggles, and Safety Glasses as a Virus Transmission Control Measure to Protect the Wearer Against Cough Droplets, Understanding the Impacts of the COVID-19 Pandemic on Small Businesses and Workers Using Quantitative and Qualitative Methods, Development of Harmonized COVID-19 Occupational Questionnaires. First things first.
TEM images were characterized by open chain-like agglomerates of very fine primary particles (Fig. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide, This PDF is available to Subscribers Only. In the overlap region between the SMPD/LDMA and APS, the visual agreement of the size distributions obtained with the two instruments was reasonably good following transformation of aerodynamic diameter to an estimated equivalent-sphere projected area diameter, and only varied appreciably for substrates of very high or low density. Commonly used prosthetic materials include PMMA, Vitallium, and porcelain, and the dust created from grinding them may pose various health hazards to oral care workers, such as pulmonary fibrosis, silicosis, allergic pneumonia, lung granuloma, asthma, and lung cancer58. 
Zhang K, et al. The three types of grinding dust particles showed had wide range of size distributions that significantly differed from each other.
P values less than 0.05 were stated as statistically significant. Clearly, there is further research to be carried out in this area. This is a harmful form of dust that can pass into the lungs, bypassing the nose, throat and upper respiratory tract. While still bimodal, the lower mode occurs at a much higher diameter than for previous substrates (Table 1). Moreover, there was no significant difference between the Vitallium group and the PMMA group. Previous animal experiments showed that the relatively smaller particle sizes of porcelain and Vitallium dust particles may be more toxic than larger particles15. Liu SJ, et al. 2ag. FOIA Finally, the cells were gently rinsed with PBS and observed under a fluorescence microscope. High-speed grinding has been used as the basis for testing the hypothesis that ultrafine particles do not form a substantial component of mechanically generated aerosols. 3a). 4b,d,f,h, the pseudopods of the cells were elongated, and the nuclei were displaced. During a typical experimental sample run, the grinding substrate was attached to a holder. 3e). Unless you're allergic to dust, you probably don't think much about the dangers of dust. Received 2 April 2002; in final form 22 July 2002. The aerosol that resulted from grinding a PTFE substrate is shown in Fig.
Particle binding to cell surface receptors such as scavenger and Toll-like receptors may induce polymerization of the actin cytoskeleton and the formation of pseudopods to envelop the dust particles28. and K.Z. They are readily available and their use raises fewer ethical issues than using human macrophages. The cells showed irregular shapes, the number of pseudopods was increased, the pseudopods were elongated to different lengths, and some cells even appeared balloon-like. 2017YFC1104703), National Natural Science Foundation of China (Nos. solid circles for the SMPS/NDMA configuration, hollow circles for the SMPS/LDMA configuration and solid triangles for the APS). 2a). Pulmonary toxicity and extrapulmonary tissue distribution of metals after repeated exposure to different welding fumes. Complete culture medium (DMEM supplemented with 10% inactivated serum) was used as a negative control. Suppressive oligodeoxynucleotides inhibit silica induced pulmonary inflammation. In this case, it was not possible to obtain meaningful information from the samples using EDX. To quantitatively present the particle size statistics for the combined aerosol instruments, a log-normal particle size distribution was assumed and fitted to the ultrafine and coarse modes in the experimental data (Fig. Protective effect of polysaccharides from Sargassum horneri against oxidative stress in RAW264.7 cells. Small, nanometer scale particles [4.22 nm < dp (particle diameter) < 100 nm] were characterized using a scanning mobility particle sizer (SMPS) configured with a nano differential mobility analyzer (DMA) (electrostatic classifier model 3080 using a DMA model 3085 and a condensation particle counter model 3022A; TSI Inc., St Paul, MN). Three wells were designated for each type of dust. contributed to the analysis of the experiments. Accessibility Multivariate linear regression, one-way ANOVA, and LSD test were used to compare differences between groups. However, the experimental results showed that Vitallium abrasive dust caused slightly greater damage to the RAW264.7 cells, but the difference was not statistically significant and may be related to the dust particle structures, element compositions or way of entering the body. National Institute for Occupational Safety and Health, Division of Applied Research and Technology, 4676 Columbia Parkway, Cincinnati, OH 45226, USA. The information is extracted from Fig. Rajaram MVS, et al. Furthermore, under high magnification (400), as shown in Fig. Among the three types of denture grinding dust, the percentage of ceramic abrasive grains with a diameter of<5m was the highest (21.05%); therefore, porcelain powder may cause more lung damage than is caused by other dust types. After 24h and 48h of cultivation, the dust adsorbed onto the cell surface or entered the cells. Author to whom correspondence should be addressed. The porcelain group (e, f) consisted of cube-shaped particles with sharp edges. The micrograph also revealed evidence of large numbers of nanometer size particles on the substrate, although it is not clear whether these originated from the granite substrate or the grinding tool itself. Amphiregulin may be a new biomarker of classically activated macrophages. However, apart from these studies there is little in the literature to indicate the likely contribution of mechanical processes to ultrafine aerosols in the workplace. Relationship of incisive papilla to maxillary incisors and canines: original research. These particles can not only find their way to the lungs, but the material dust is made up of can come with its own unique hazards. 3ae. 2a). Careers. Fig. 
HEPA-filtered, particle-free air was pulled upward through a stainless steel chamber (0.914 m long, 0.813 m wide, 1.19 m tall) using a commercially available, industrial air cleaner (model 73-800G; ACE Corp., St Louis, MO) (Fig. 1School and Hospital of Stomatology, China Medical University, Liaoning Provincial Key Laboratory of Oral Diseases, Shenyang, 110002 China, 2Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, 100083 China, 3Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, 100083 China, 4The Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, 322000 China. Critical role of MARCO in crystalline silica-induced pulmonary inflammation. Therefore, clinicians who regularly work with these materials should wear the appropriate personal protection equipment to minimize exposure and reduce the health risks caused by these particulates. Sampling errors associated with this instrument tended to be larger than those associated with either of the other instruments above 200 nm, reflecting the low particle detection rate within the instrument in this regime. The aerosol collected for TEM was, for the most part, too beam sensitive to allow imaging. In addition, free radicals can lead to lipid peroxidation of the cell membrane35. After exposure for 6, 12, 24, and 48h, 10l of MTT reagent (Sigma-Aldrich) was added to each well and incubated for 4h. Then, the supernatants were removed, 200l of DMSO was added, and the 96-well plate was shaken on a horizontal shaker for 10min. with an unused sintered aluminum oxide grinding wheel. (1993) have shown particle mobility diameter to agree well with equivalent-sphere projected area diameter for fractal-like particles <1 m. Assessing a jobsite and finding the dust generation points goes a long way to developing a dust control plan that drastically reduces the chance of dust-related harm. The Vitallium group (c, d) consisted of particles arranged in a sheet with irregular edge morphology. In vitro action of quartz on alveolar macrophage lipid peroxides. These phagosomes mature and bind to lysosomes which digest the particles with enzymes such as hydrolase and oxidase29.
Aerosols from the grinder were produced in a controlled environment, using a variety of grinding substrates, and the grinding aerosol was characterized over a particle size range from 4.22 nm to 20.5 m. Research progress on occupational hazards of coming from hard metal dust. This type also possesses the ability to enter the human system, but unlike the other two forms, it can be visible to the human eye. Learn more The new PMC design is here! It is generally assumed that aerosols generated during mechanical processes such as grinding are characterized by large particles formed through attrition. Scanning electron microscopy images of dental prosthesis grinding dust: PMMA (a), finely ground PMMA (b), Vitallium (c), finely ground Vitallium (d), porcelain (e), finely ground porcelain (f), and their composition: PMMA (g). After 30 s, grinding was conducted on the substrate for 10 s, ensuring that the aerosol number concentration was sufficiently low to suppress coagulation dynamics (typical number concentrations were <106 particles/cm3). Note that (i) the solid line for each experimental condition represents a log-normal fit of the experimental data, (ii) the error bars represent the standard error associated with three randomized replicate samples and (iii) the experimental data for all substrates have been background corrected for the Dremel tool aerosols. There is evidence that grinding of some substrates produced ultrafine particles through vaporization or combustion of the substrate material. Note that the shut-off valve closed when generating and sampling grinding aerosols.
They also induced varying degrees of cytotoxicity in RAW264.7 macrophages. After 24h, the culture medium was discarded, and a 300g/ml suspension of each of the three kinds of dust particles was added to a volume of 200l in each well for the exposure test. The aerosol produced solely by the grinding tool and the background corrected measurements for each of the substrates are presented in Fig. Variation in particle number concentration [dN/d log(dp)] as a function of equivalent-sphere projected surface area diameter for (a) the Dremel tool without a grinding substrate, (b) a granite substrate, (c) a clay ceramic substrate, (d) a steel substrate, (e) an aluminum substrate, (f) a PTFE substrate and (g) a hardwood substrate using the SMPS/NDMA (solid circles), SMPS/LDMA (hollow circles) and APS (solid triangles). As in the case of steel, it is likely that uncertainty over the density of the wood-related aerosol and the particle morphology were responsible for a poor transformation between particle aerodynamic diameter and equivalent-sphere projected area diameter. At 24h and 48h, culture supernatants were sampled from each well and analysed for LDH level using a lactate dehydrogenase kit. TEM analysis indicated a large number of particles >1 m in diameter, characterized by compact non-spherical particles with sharp edges indicative of generation through abrasive removal (Fig. The viability of the RAW264.7 cells was inversely proportional to the dust exposure time. Fig. Brown DM, Wilson MR, MacNee W, Stone V, Donaldson K. (, Kusaka Y, Kumagai S, Kyono H, Kohyama N, Shirakawa T. (, Oberdorster G, Gelein RM, Ferin J, Weiss B. Sampling was started at this point, based upon CPC measurements suggesting that the aerosol within the chamber was well mixed and that the particle number concentration did not vary appreciably over the necessary time scales. Takahashi T, et al. In this preliminary study of particle formation upon high-speed grinding we have shown that ultrafine particles are generated by a variety of substrates. shield face grinding chipping impact fsc weldclass Large numbers of single particles around 1020 nm in diameter were seen by TEM (Fig.
This process damages cells, releases dust particles, initiates re-phagocytosis, and stimulates the proliferation and aggregation of macrophages.
method of generation) (ACGIH, 1990; OSHA, 1997). Removable partial denture with molar uprighting spring: an innovative hybrid appliance. Chen SJ, Chen F. Learning and summary of lactate dehydrogenase.
Cytotoxic and genotoxic potential of respirable fraction of composite dust on human bronchial cells. contributed to material characterization, and T.L., N.C. and K.L. However, in the case of highly toxic particles such as silica, it would be important to differentiate between the aerosols generated by these two sources. dust particle weight To prevent cross-contamination, new grinding wheels were used for each substrate tested.
Comparison of ROS levels in RAW264.7 macrophages exposed to five different concentrations of PMMA dust (a), Vitallium dust (b), and porcelain dust (c) for 6h, 12h, 24h, and 48h. Grinding dust toxicities were closely correlated with their physicochemical properties, including particle diameter, shape, surface area, and constituent elements22,23. The middle form of dust is classified with an approximate 10 micron wide diameter. Fig. 1. These cell samples were observed under an inverted phase-contrast microscope. After 6h of exposure, numerous cells had extended pseudopods, indicating active removal of particles26. Clearly, a better indicator of the source of an ultrafine particle would be obtained through single particle elemental analysis. window.hsFormsOnReady.push(()=>{ Microscopic observation revealed that the dust particles accumulated on the RAW264.7 macrophage surfaces, which caused pseudopod elongation, irregular cell morphology, and ballooning. and transmitted securely. However, the grinding dust concentrations used in this experiment do not necessarily represent the actual concentrations of grinding dust that would actually enter the lungs during occupational exposure39. Wen ZS, et al. The dust from grinding dental prosthesis made of these three materials was characterized in terms of morphology, particle size, and elemental composition. Researchers found that RAW macrophage cells effectively internalized both 0.1- and 0.5-m-diameter dust particles. RAW264.7 macrophages were seeded in a 96-well plate (1104 cells/well) and exposed to 200l of the grinding dust suspension at concentrations of 50, 150, 300, 450, and 600gmll. The particles were generated using the 3D printed dust generator (PRIZE) and measurement of their size distribution was made by the Optimal Particle Sizer (OPS). In the case of PTFE and steel, the ultrafine particle morphology indicates formation through nucleation, suggesting that temperatures were sufficiently high at the grinding interface to lead to vaporization or combustion of the substrate. 4a,c,e,g, no abrasive grinding dust was found to induce apoptosis of the RAW264.7 cells. Particles<5m in diameter can damage alveolar macrophages and cause silicosis, pulmonary fibrosis, and other respiratory diseases25. Currently, there are few reports on the effects of prosthesis grinding powder in vivo. 1, the morphology of the PMMA group particles (a, b) was irregular and very different in size. The viability of the RAW264.7 cells exposed to the three kinds of dust was lower than that of the blank control group cells (Fig. Twelve, twenty-four and forty-eight hours after dust treatment, cell viability was significantly reduced. There's usually no need to worry about the typical dust in a home, but those working in the industrial sector needdust controland can come into contact with these harmful, micro-sized dust particles on a regular basis. Shrestha S, et al. Through TEM analysis, researchers found that dust particles can enter human bronchial epithelial cells.