Objectives
To determine the shaping ability of reciprocating files without/with post-manufacturing heat treatment (Reciproc®/Reciproc blue®, VDW) when used by six operators of similar level of ...experience.
Materials and methods
Plastic training blocs with curved root canals (5 mm radius, 55° angle) were mounted in a dental manikin. Each operator prepared six specimens with each instrument system using the file sizes R25, R40 and R50 consecutively. Specimens were photographed, and deviations from the centre of the canal were measured at intervals of 0.5 mm and averaged for the apical, middle and coronal part of the canal. Data were tested for significance using the Mann-Whitney
U
test and two-way ANOVA with instrument systems and operators serving as factors.
Results
Deviations were observed towards the outer curvature in the apical and coronal and to the inner curvature in the middle segment of the canal. They were larger after using larger size instruments and were smaller when using Reciproc blue® compared to Reciproc®. Significant differences among operators were observed in the middle (all sizes) and coronal part of the canals (only sizes R25 und R40). Coronally, interaction between the main factors was significant as well.
Conclusions
Post-manufacturing heat treatment significantly improved shaping ability of the reciprocating file system Reciproc®. The observed differences among operators suggest the possibility of further improvement by providing specific training for prospective users.
Clinical relevance
Maintenance of root canal curvature may be improved by using post-manufacturing heat-treated instruments, but specific training should be recommended as well.
Abstract
Background
Per- and polyfluoroalkyl substances (PFAS) are highly persistent chemicals that have been detected in the serum of over 98% of the US population. Studies among highly exposed ...individuals suggest an association with perfluorooctanoic acid (PFOA) exposure and kidney cancer. It remains unclear whether PFOA or other PFAS are renal carcinogens or if they influence risk of renal cell carcinoma (RCC) at concentrations observed in the general population.
Methods
We measured prediagnostic serum concentrations of PFOA and 7 additional PFAS in 324 RCC cases and 324 individually matched controls within the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Multivariable conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CIs) relating serum PFAS concentrations and RCC risk. Individual PFAS were modeled continuously (log2-transformed) and categorically, with adjustment for kidney function and additional potential confounders. All statistical tests were 2-sided.
Results
We observed a positive association with RCC risk for PFOA (doubling in serum concentration, ORcontinuous = 1.71, 95% CI = 1.23 to 2.37, P = .002) and a greater than twofold increased risk among those in the highest quartile vs the lowest (OR = 2.63, 95% CI = 1.33 to 5.20, Ptrend = .007). The association with PFOA was similar after adjustment for other PFAS (ORcontinuous = 1.68, 95% CI = 1.07 to 2.63, P = .02) and remained apparent in analyses restricted to individuals without evidence of diminished kidney function and in cases diagnosed 8 or more years after phlebotomy.
Conclusions
Our findings add substantially to the weight of evidence that PFOA is a renal carcinogen and may have important public health implications for the many individuals exposed to this ubiquitous and highly persistent chemical.
Searching for quantum functionalities requires access to the electronic structure, constituting the foundation of exquisite spin-valley-electronic, topological, and many-body effects. All-optical ...band-structure reconstruction could directly connect electronic structure with the coveted quantum phenomena if strong lightwaves transported localized electrons within preselected bands. Here, we demonstrate that harmonic sideband (HSB) generation in monolayer tungsten diselenide creates distinct electronic interference combs in momentum space. Locating these momentum combs in spectroscopy enables super-resolution tomography of key band-structure details in situ. We experimentally tuned the optical-driver frequency by a full octave and show that the predicted super-resolution manifests in a critical intensity and frequency dependence of HSBs. Our concept offers a practical, all-optical, fully three-dimensional tomography of electronic structure even in microscopically small quantum materials, band by band.
Glyphosate is the most commonly used herbicide worldwide, with both residential and agricultural uses. In 2015, the International Agency for Research on Cancer classified glyphosate as "probably ...carcinogenic to humans," noting strong mechanistic evidence and positive associations for non-Hodgkin lymphoma (NHL) in some epidemiologic studies. A previous evaluation in the Agricultural Health Study (AHS) with follow-up through 2001 found no statistically significant associations with glyphosate use and cancer at any site.
The AHS is a prospective cohort of licensed pesticide applicators from North Carolina and Iowa. Here, we updated the previous evaluation of glyphosate with cancer incidence from registry linkages through 2012 (North Carolina)/2013 (Iowa). Lifetime days and intensity-weighted lifetime days of glyphosate use were based on self-reported information from enrollment (1993-1997) and follow-up questionnaires (1999-2005). We estimated incidence rate ratios (RRs) and 95% confidence intervals (CIs) using Poisson regression, controlling for potential confounders, including use of other pesticides. All statistical tests were two-sided.
Among 54 251 applicators, 44 932 (82.8%) used glyphosate, including 5779 incident cancer cases (79.3% of all cases). In unlagged analyses, glyphosate was not statistically significantly associated with cancer at any site. However, among applicators in the highest exposure quartile, there was an increased risk of acute myeloid leukemia (AML) compared with never users (RR = 2.44, 95% CI = 0.94 to 6.32, Ptrend = .11), though this association was not statistically significant. Results for AML were similar with a five-year (RRQuartile 4 = 2.32, 95% CI = 0.98 to 5.51, Ptrend = .07) and 20-year exposure lag (RRTertile 3 = 2.04, 95% CI = 1.05 to 3.97, Ptrend = .04).
In this large, prospective cohort study, no association was apparent between glyphosate and any solid tumors or lymphoid malignancies overall, including NHL and its subtypes. There was some evidence of increased risk of AML among the highest exposed group that requires confirmation.
When intense lightwaves accelerate electrons through a solid, the emerging high-order harmonic (HH) radiation offers key insights into the material
. Sub-optical-cycle dynamics-such as dynamical ...Bloch oscillations
, quasiparticle collisions
, valley pseudospin switching
and heating of Dirac gases
-leave fingerprints in the HH spectra of conventional solids. Topologically non-trivial matter
with invariants that are robust against imperfections has been predicted to support unconventional HH generation
. Here we experimentally demonstrate HH generation in a three-dimensional topological insulator-bismuth telluride. The frequency of the terahertz driving field sharply discriminates between HH generation from the bulk and from the topological surface, where the unique combination of long scattering times owing to spin-momentum locking
and the quasi-relativistic dispersion enables unusually efficient HH generation. Intriguingly, all observed orders can be continuously shifted to arbitrary non-integer multiples of the driving frequency by varying the carrier-envelope phase of the driving field-in line with quantum theory. The anomalous Berry curvature warranted by the non-trivial topology enforces meandering ballistic trajectories of the Dirac fermions, causing a hallmark polarization pattern of the HH emission. Our study provides a platform to explore topology and relativistic quantum physics in strong-field control, and could lead to non-dissipative topological electronics at infrared frequencies.
Zusammenfassung
Bei Kompositfüllungen im Seitenzahngebiet empfiehlt sich zur Herstellung straffer Approximalkontakte die Verwendung von Teilmatrizen, anatomisch geformter Kunststoff-Interdentalkeile ...und von Spannringen. Approximal sehr tiefe Defekte müssen zweizeitig restauriert werden. Dabei wird als erster Schritt die Stufe mithilfe schmaler Metallmatrizen im Matrizenspanner aufgebaut. Gute Approximalkontakte sind ein wesentliches Qualitätsmerkmal von Seitenzahnfüllungen. Fehlende Approximalkontakte führen in der Regel zur Impaktion von Speiseresten. Abgesehen von der Komforteinbuße für den Patienten kann es zur Schädigung des Zahnhalteapparats und/oder zu einer Sekundärkaries kommen.
•Many pesticides are known to have thyroid-disrupting properties.•Prospective study of farmers to evaluate 44 pesticides and thyroid cancer.•Thyroid cancer associated with metalaxyl, lindane, and ...carbaryl (inverse).•First study to comprehensively evaluate occupational pesticides and thyroid cancer.
Many pesticides are known to have thyroid-disrupting properties. However, few studies have evaluated the association between specific pesticide ingredients and risk of thyroid cancer. We investigated self-reported pesticide use and incident thyroid cancer in the Agricultural Health Study (AHS), a large cohort of occupationally-exposed male pesticide applicators.
The AHS is a prospective cohort of licensed pesticide applicators in Iowa and North Carolina. At enrollment (1993–1997) and follow-up (1999–2005), participants reported use of 50 pesticides. We characterized exposure as ever use (44 pesticides with ≥5 exposed cases) and by cumulative intensity-weighted lifetime days (22 pesticides with ≥10 exposed cases), a metric that accounts for factors that influence exposure. We estimated hazard ratios (HR) and 95% confidence intervals (CI) using Cox regression for incident thyroid (n = 85 cases) cancer among male participants using follow-up through 2014/2015.
Use of the fungicide metalaxyl (HR = 2.03, CI:1.16–3.52) and the organochlorine insecticide lindane (HR = 1.74, CI:1.06–2.84) was associated with increased risk of thyroid cancer. The herbicide chlorimuron-ethyl was inversely associated with risk when we restricted to papillary thyroid cancer, the most common subtype (HR = 0.52, CI:0.28–0.96). High use of the insecticide carbaryl (>median intensity-weighted days) was inversely associated with thyroid cancer (HR = 0.20, CI:0.08–0.53, ptrend = 0.001).
In this large cohort study, we observed increased risk of thyroid cancer associated with use of metalaxyl and lindane, and an inverse association with carbaryl. More work is needed to understand the potential role of these chemicals in thyroid carcinogenesis.
Farming and pesticide use have previously been linked to non-Hodgkin lymphoma (NHL), chronic lymphocytic leukemia (CLL) and multiple myeloma (MM). We evaluated agricultural use of specific ...insecticides, fungicides, and fumigants and risk of NHL and NHL-subtypes (including CLL and MM) in a U.S.-based prospective cohort of farmers and commercial pesticide applicators. A total of 523 cases occurred among 54,306 pesticide applicators from enrollment (1993-97) through December 31, 2011 in Iowa, and December 31, 2010 in North Carolina. Information on pesticide use, other agricultural exposures and other factors was obtained from questionnaires at enrollment and at follow-up approximately five years later (1999-2005). Information from questionnaires, monitoring, and the literature were used to create lifetime-days and intensity-weighted lifetime days of pesticide use, taking into account exposure-modifying factors. Poisson and polytomous models were used to calculate relative risks (RR) and 95% confidence intervals (CI) to evaluate associations between 26 pesticides and NHL and five NHL-subtypes, while adjusting for potential confounding factors. For total NHL, statistically significant positive exposure-response trends were seen with lindane and DDT. Terbufos was associated with total NHL in ever/never comparisons only. In subtype analyses, terbufos and DDT were associated with small cell lymphoma/chronic lymphocytic leukemia/marginal cell lymphoma, lindane and diazinon with follicular lymphoma, and permethrin with MM. However, tests of homogeneity did not show significant differences in exposure-response among NHL-subtypes for any pesticide. Because 26 pesticides were evaluated for their association with NHL and its subtypes, some chance finding could have occurred. Our results showed pesticides from different chemical and functional classes were associated with an excess risk of NHL and NHL subtypes, but not all members of any single class of pesticides were associated with an elevated risk of NHL or NHL subtypes. These findings are among the first to suggest links between DDT, lindane, permethrin, diazinon and terbufos with NHL subtypes.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•AGRICOH analyzed cancer incidence in >248,000 agricultural workers from 6 countries.•Cancer overall occurred less in agricultural workers than in the general population.•An excess was found for ...multiple myeloma, melanoma of the skin, and prostate cancer.•Direction of risk was largely consistent across cohorts with a few deviations.•A large deficit of larynx and lung cancers was observed in nearly all cohorts.
Agricultural work can expose workers to potentially hazardous agents including known and suspected carcinogens. This study aimed to evaluate cancer incidence in male and female agricultural workers in an international consortium, AGRICOH, relative to their respective general populations.
The analysis included eight cohorts that were linked to their respective cancer registries: France (AGRICAN: n = 128,101), the US (AHS: n = 51,165, MESA: n = 2,177), Norway (CNAP: n = 43,834), Australia (2 cohorts combined, Australian Pesticide Exposed Workers: n = 12,215 and Victorian Grain Farmers: n = 919), Republic of Korea (KMCC: n = 8,432), and Denmark (SUS: n = 1,899). For various cancer sites and all cancers combined, standardized incidence ratios (SIR) and 95% confidence intervals (CIs) were calculated for each cohort using national or regional rates as reference rates and were combined by random-effects meta-analysis.
During nearly 2,800,000 person-years, a total of 23,188 cancers were observed. Elevated risks were observed for melanoma of the skin (number of cohorts = 3, meta-SIR = 1.18, CI: 1.01–1.38) and multiple myeloma (n = 4, meta-SIR = 1.27, CI: 1.04–1.54) in women and prostate cancer (n = 6, meta-SIR = 1.06, CI: 1.01–1.12), compared to the general population. In contrast, a deficit was observed for the incidence of several cancers, including cancers of the bladder, breast (female), colorectum, esophagus, larynx, lung, and pancreas and all cancers combined (n = 7, meta-SIR for all cancers combined = 0.83, 95% CI: 0.77–0.90). The direction of risk was largely consistent across cohorts although we observed large between-cohort variations in SIR for cancers of the liver and lung in men and women, and stomach, colorectum, and skin in men.
The results suggest that agricultural workers have a lower risk of various cancers and an elevated risk of prostate cancer, multiple myeloma (female), and melanoma of skin (female) compared to the general population. Those differences and the between-cohort variations may be due to underlying differences in risk factors and warrant further investigation of agricultural exposures.
Self-reported shingles was associated with history of high pesticide exposure events (HPEE) in licensed pesticide applicators aged >60 years in the Agricultural Health Study (AHS). In the current ...study, using AHS-linked Medicare claims data, we examined incident shingles in relation to pesticide-related illness and pesticide poisoning, as well as HPEE.
We studied 22,753 licensed private pesticide applicators (97% white males, enrolled in the AHS 1993-97), aged ≥66 years with >12 consecutive months of Medicare fee-for-service hospital and outpatient coverage between 1999 and 2016. Incident shingles was identified based on having ≥1 shingles claim(s) after 12 months without claims. At AHS enrollment, participants were asked if they ever sought medical care or were hospitalized for pesticide-related illness, and a supplemental questionnaire (completed by 51%) asked about HPEE and poisoning. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards regression, adjusted for age, sex, race, state, and education.
Over 192,053 person-years (PY), 2396 applicators were diagnosed with shingles (10.5%; age-standardized rate, 13.6 cases per 1,000PY), with higher rates among those reporting hospitalization for pesticide-related illness, pesticide poisoning, and HPEE (23.2, 22.5, and 16.6 per 1,000PY, respectively). In adjusted models, shingles was associated with hospitalization for pesticide-related illness (HR 1.69; 1.18, 2.39), poisoning (1.49; 1.08, 1.46), and HPEE (1.23; 95% CI = 1.03, 1.46), especially HPEE plus medical care/poisoning (1.78; 1.30, 2.43).
These novel findings suggest that acute, high-level, and clinically impactful pesticide exposures may increase risk of shingles in subsequent years to decades following exposure.
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