Automotive braking is a source of highly charged aerosol particles.

Although the last several decades have seen a dramatic reduction in emissions from vehicular exhaust, nonexhaust emissions (e.g., brake and tire wear) represent an increasingly significant class of traffic-related particulate pollution. Aerosol particles emitted from the wear of automotive brake pads contribute roughly half of the particle mass attributed to nonexhaust sources, while their relative contribution to urban air pollution overall will almost certainly grow coinciding with vehicle fleet electrification and the transition to alternative fuels. To better understand the implications of this growing prominence, a more thorough understanding of the physicochemical properties of brake wear particles (BWPs) is needed. Here, we investigate the electrical properties of BWPs as emitted from ceramic and semi-metallic brake pads. We show that up to 80% of BWPs emitted are electrically charged and that this fraction is strongly dependent on the specific brake pad material used. A dependence of the number of charges per particle on charge polarity and particle size is also demonstrated. We find that brake wear produces both positive and negative charged particles that can hold in excess of 30 elementary charges and show evidence that more negative charges are produced than positive. Our results will provide insights into the currently limited understanding of BWPs and their charging mechanisms, which potentially have significant implications on their atmospheric lifetimes and thus their relevance to climate and air quality. In addition, our study will inform future efforts to remove BWP emissions before entering the atmosphere by taking advantage of their electric charge.

Charge Redistribution in Mechanochemical Reactions for Solid Interfaces.

Mechanochemical strategies are widely used in various fields, ranging from friction and wear to mechanosynthesis, yet how the mechanical stress activates the chemical reactions at the electronic level is still open. We used first-principles density functional theory to study the rule of the stress-modified electronic states in transmitting mechanical energy to trigger chemical responses for different mechanochemical systems. The electron density redistribution among initial, transition, and final configurations is defined to correlate the energy evolution during reactions. We found that stress-induced changes in electron density redistribution are linearly related to activation energy and reaction energy, indicating the transition from mechanical work to chemical reactivity. The correlation coefficient is defined as the term "interface reactivity coefficient" to evaluate the susceptibility of chemical reactivity to mechanical action for material interfaces. The study may shed light on the electronic mechanism of the mechanochemical reactions behind the fundamental model as well as the mechanochemical phenomena.

Observing and Modeling the Wear Process of Heterogeneous Interface.

Understanding and controlling the wear process of heterogeneous interfaces between soft and hard phases is crucial for designing and fabricating materials, such as improving the wear resistance of particle reinforced metal matrix composites and the accuracy and efficiency of chemical mechanical polishing. However, the wear process can be hardly observed, as interfaces are buried under the surface. Here, we proposed a nanowear test method by combining focused ion beam cutting to expose interfaces, atomic force microscopy to rub against interfaces, and scanning electron microscope to characterize the interface damage. Using this method, three typical wear forms had been observed in Al/SiC composite, i.e., merely matrix wear, particle fracture, and particle pullout. A theoretical model was proposed that revealed that the increasing interfacial friction would induce particle fracture or pullout, depending on the particle edge angle and tip edge angle. This work sheds light on wear control in composites and nanofabrication.

Graphene Failure under MPa: Nanowear of Step Edges Initiated by Interfacial Mechanochemical Reactions.

The low wear resistance of macroscale graphene coatings does not match the ultrahigh mechanical strength and chemical inertness of the graphene layer itself; however, the wear mechanism responsible for this issue at low mechanical stress is still unclear. Here, we demonstrate that the susceptibility of the graphene monolayer to wear at its atomic step edges is governed by the mechanochemistry of frictional interfaces. The mechanochemical reactions activated by chemically active SiO2 microspheres result in atomic attrition rather than mechanical damage such as surface fracture and folding by chemically inert diamond tools. Correspondingly, the threshold contact stress for graphene edge wear decreases more than 30 times to the MPa level, and mechanochemical wear can be described well with the mechanically assisted Arrhenius-type kinetic model, i.e., exponential dependence of the removal rate on the contact stress. These findings provide a strategy for improving the antiwear of graphene-based materials by reducing the mechanochemical interactions at tribological interfaces.

Robust and Lubricating Interface Semi-Interpenetrating Network on Inert Polymer Substrates Enabled by Subsurface-Initiated Polymerization.

Lubricating hydrogel coatings on inert rubber and plastic surfaces significantly reduce friction and wear, thus enhancing material durability and lifespan. However, achieving optimal hydration lubrication typically requires a porous polymer network, which unfortunately reduces their mechanical strength and limits their applicability where robust durability and wear-resistance are essential. In the research, a hydrogel coating with remarkable wear resistance and surface stability is developed by forming a semi-interpenetrating polymer network with polymer substrate at the interface. By employing a good solvent swelling method, monomers, and photoinitiators are embedded within the substrates' subsurface, followed by in situ polymerization under ultraviolet light, creating a robust semi-interpenetrating and entangled network structure. This approach, offering a thicker energy-dissipating layer, outperforms traditional surface modifications in wear resistance while preserving anti-fatigue, hydrophilicity, oleophobicity, and other properties. Adaptable to various rubber and plastic substrates by using suitable solvents, this method provides an efficient solution for creating durable, lubricating surfaces, broadening the potential applications in multiple industries.

Evaluation of a Retinal Projection Laser Eyeware in Patients with Visual Impairment Caused by Corneal Diseases in a Randomized Trial.

PURPOSE: Patients with incurable corneal diseases experience visual impairment (VI) despite having a healthy retina and optic pathway. Low-vision aids (LVAs) can optimize the use of remaining vision through magnification and contrast enhancement, but do not harness the full visual capacity because they rely on the optic media. Therefore, we investigated a novel laser eyewear (LEW) technology that bypasses the anterior segment of the eye. Images captured by an integrated camera are projected directly onto the retina using a low-energy laser. The patient is able to view a full-color video, realized as augmented reality. We aimed to evaluate the efficacy of the LEW to enhance the vision of individuals with corneal diseases. DESIGN: Prospective, randomized, crossover clinical trial. PARTICIPANTS: We examined the retinal projection glasses in 21 patients (25-69 years) with VI (0.7 logarithm of the minimum angle of resolution [logMAR] or worse) resulting from corneal diseases. Patients with comorbidities that impact vision, such as retinal disorders, were excluded. METHODS: Standardized measurements of visual acuity (VA) for near vision (NV) and distance vision (DV) were conducted using ETDRS charts with the respective best correction (BC) and then with LEW. In addition reading speed, vision-related quality of life (QoL) and capacity to carry out daily tasks were assessed at an initial visit and at 2 subsequent visits after a home phase with and without the device. Six weeks after last use of the LEW, an ophthalmologic examination including spectral-domain-OCT or full-field-electroretinography was conducted and compared with baseline findings to evaluate the safety of the device. Four patients participated and completed a subsequent 12-month follow-up phase. MAIN OUTCOME MEASURES: Improvement of VA using the LEW. Secondary objectives included safety, reading speed, QoL, and usability in daily activities. RESULTS: The mean VA in patients with VI was improved by 0.43 logMAR in DV using the LEW compared with BC (P < 0.0001). Using the ×2 magnification mode of the LEW resulted in an average improvement of 0.66 logMAR compared with BC (P < 0.0001). In NV, an increase of 0.47 logMAR was achieved compared with BC (P < 0.0001). Although only 4 of 21 participants were able to read with BC, 17 of 21 participants were able to read with the LEW. Quality of life significantly improved in the 17 participants who completed all visits. CONCLUSIONS: We demonstrated that the retinal projection glasses resulted in enhanced VA for all participants by directly projecting images onto the intact retina. In future, the LEW could represent a new option as an LVA for patients with corneal diseases. No pathological alterations were observed in the safety assessments. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Is a blunt sword pointless? Tooth wear impacts puncture performance in Tasmanian devil canines.

As teeth wear, their shapes change and functional features can be dulled or lost, presumably making them less effective for feeding. However, we do not know the magnitude and effect of this wear. Using Tasmanian devil canines as a case study, we investigated the impact of wear on puncture in pointed teeth. We measured aspects of shape impacted by wear (tip sharpness, height and volume) in teeth of varying wear followed by 3D printing of real and theoretical forms to carry out physical puncture tests. Tooth wear acts in two ways: by blunting tooth tips, and decreasing height and volume, both of which impact performance. Sharper tips in unworn teeth decrease the force and energy required to puncture compared with blunter worn teeth, while taller unworn teeth provide the continuous energy necessary to propagate fracture relative to shorter worn teeth. These wear-modulated changes in shape necessitate more than twice the force to drive worn teeth into ductile food and decrease the likelihood of puncture success.

Evaluating infectious disease outbreak potential and mitigation effectiveness on cruise ships.

The cruise ship sector is a major part of the tourism industry, and an estimated over 30 million passengers are transformed worldwide each year. Cruise ships bring diverse populations into proximity for many days, facilitating the transmission of respiratory illnesses. The objective of this study is to develop a modeling framework to inform the development of viable disease risk management policies and measures to control disease outbreaks on cruises. Our model, parameterized and calibrated using the data of the COVID-19 outbreak on the Diamond Princess cruise ship in 2020, is used to assess the impact of the mitigation measures such as mask wearing, vaccination, on-board and pre-traveling testing measures. Our results indicate mask wearing in public places as the cheapest and most affordable measure can drop the number of cumulative confirmed cases by almost 50%. This measure along with the vaccination by declining the number of the cumulative confirmed cases by more than 94% is the most effective measure to control outbreaks on cruises. According to our findings, outbreaks are more predominant in the passenger population than the crew members, however, the protection measures are more beneficial if they are applied by both crew members and passengers. Regarding the testing measure, pre-traveling testing is more functional than the on-board testing to control outbreaks on cruises.

Stereomicroscopic analysis of cut marks inflicted by a knife with blade damage.

Skeletal cut mark analysis provides relevant information on the general class characteristics of suspect knife. However, there is a lack of research on the influence of blade damage on cut mark analysis. This study aimed to thoroughly investigate the effects of damaged knife blades on cut marks' morphological and morphometrical characteristics. Fifteen undamaged, non-serrated knives were used to cut human ribs to make control cut marks. The knife blades were then damaged by a series of cuts on the bones. A comparison was made between the control cuts and 3 groups of cut marks inflicted by blades that had been damaged to different degrees. The results showed that the damaged blades created wider cut marks than undamaged one. Kerf morphology was likely to imitate the cuts made by the serrated blades such as an elliptical shape, a V-shaped cross-section and the presence of coarse striations. Wear-related features can affect cut mark analysis as the marks left behind by blades damaged to different degrees showed dissimilar dimensions and morphologies. The findings of this study can be applied to a forensic investigation when cut marks were caused by a knife with a damaged blade.

Photoaged Tire Wear Particles Leading to the Oxidative Damage on Earthworms (Eisenia fetida) by Disrupting the Antioxidant Defense System: The Definitive Role of Environmental Free Radicals.

Tire wear particles (TWPs) have caused increasing concerns due to their detrimental effects on the soil ecosystem. However, the role of weathering in altering the toxicity of TWP to soil organisms is poorly understood. In this study, the toxicity of original and photoaged TWP was compared using earthworms (Eisenia fetida) as soil model organisms. The obtained results indicated that photoaging of TWP resulted in an increase of environmentally persistent free radicals (EPFRs) from 3.69 × 1017 to 5.20 × 1017 spin/g. Meanwhile, photoaged TWP induced the changes of toxic endpoint in E. fetide, i.e., the increase of the weight loss and death ratio from 0.0425 to 0.0756 g/worm and 23.3 to 50% compared to original TWP under a 10% concentration, respectively. Analyses of transcriptomics, antioxidant enzyme activity, and histopathology demonstrated that the enhanced toxicity was mainly due to oxidative damage, which was induced by disruption in the antioxidant defense system. Free-radical quenching and correlation analysis further suggested that the excessive production of ex vivo reactive oxygen species, induced by EPFRs, led to the exhaustion of the antioxidant defense system. Overall, this work provides new insights into the potential hazard of the weathered TWP in a soil environment and has significant implications for the recycling and proper disposal of spent tire particles.

Nanoscale Abrasive Wear of Polyethylene: A Novel Approach To Probe Nanoplastic Release at the Single Asperity Level.

There is a growing concern that nanoplastic pollution may pose planetary threats to human and ecosystem health. However, a quantitative and mechanistic understanding of nanoplastic release via nanoscale mechanical degradation of bulk plastics and its interplay with photoweathering remains elusive. We developed a lateral force microscope (LFM)-based nanoscratch method to investigate mechanisms of nanoscale abrasive wear of low-density polyethylene (LDPE) surfaces by a single sand particle (simulated by a 300 nm tip) under environmentally relevant load, sliding motion, and sand size. For virgin LDPE, we found plowing as the dominant wear mechanism (i.e., deformed material pushed around the perimeter of scratch). After UVA-weathering, the wear mechanism of LDPE distinctively shifted to cutting wear (i.e., deformed material detached and pushed to the end of scratch). The shift in the mechanism was quantitatively described by a new parameter, which can be incorporated into calculating the NP release rate. We determined a 10-fold higher wear rate due to UV weathering. We also observed an unexpected resistance to initiate wear for UV-aged LDPE, likely due to nanohardness increase induced by UV. For the first time, we report 0.4-4 × 10-3 µm3/µm sliding distance/µN applied load as an initial approximate nanoplastic release rate for LDPE. Our novel findings reveal nanoplastic release mechanisms in the environment, enabling physics-based prediction of the global environmental inventory of nanoplastics.

Beware of atrial pacing-induced ventricular depolarization: A case of lead malfunction.

Although ventricular capture during the atrial threshold test is possible, there are rare reports on the insulation defect and inactive leads thereof. In this case, we present a pacemaker-dependent patient with a history of pacemaker generator replacements. The patient experienced ventricular capture induced by atrial pacing due to adhesion of the atrial and ventricular leads with an insulation defect. The atrial lead was abandoned and a new lead was implanted. However, there was a significant decrease in ventricular impedance detected shortly after the new lead was implanted. When observing the phenomenon of atrial pacing-induced ventricular depolarization, one uncommon reason to consider is lead adhesive wear. It is important to pay attention to the contact and bending sites of the leads.

Environmental fate of tire-rubber related pollutants 6PPD and 6PPD-Q: A review.

To enhance tire durability, the antioxidant N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) is used in rubber, but it converts into the toxic 6PPD quinone (6PPD-Q) when exposed to oxidants like ozone (O3), causing ecological concerns. This review synthesizes the existing data to assess the transformation, bioavailability, and potential hazards of two tire-derived pollutants 6PPD and 6PPD-Q. The comparative analysis of different thermal methods utilized in repurposing waste materials like tires and plastics into valuable products are analyzed. These methods shed light on the aspects of pyrolysis and catalytic conversion processes, providing valuable perspectives into optimizing the waste valorization and mitigating environmental impacts. Furthermore, we have examined the bioavailability and potential hazards of chemicals used in tire manufacturing, based on the literature included in this review. The bioavailability of these chemicals, particularly the transformation of 6PPD to 6PPD-Q, poses significant ecological risks. 6PPD-Q is highly bioavailable in aquatic environments, indicating its potential for widespread ecological harm. The persistence and mobility of 6PPD-Q in the environment, along with its toxicological effects, highlight the critical need for ongoing monitoring and the development of effective mitigation strategies to reduce its impact on both human health and ecosystem. Future research should focus on understanding the chronic effects of low-level exposure to these compounds on both terrestrial and aquatic ecosystems, as well as the potential for bioaccumulation in the food chain. Additionally, this review outlines the knowledge gaps, recommending further research into the toxicity of tire-derived pollutants in organisms and the health implications for humans and ecosystems.

Effects of erosion and abrasion on resin-matrix ceramic CAD/CAM materials: An in vitro investigation.

The aim of the study was to evaluate the effects of erosion and abrasion on resin-matrix ceramic CAD/CAM materials [CERASMART (GC); VITA ENAMIC (VITA Zahnfabrik); Lava Ultimate (3 M)] in comparison to feldspar ceramic (VITABLOCS Mark II, VITA Zahnfabrik) and resin composite materials (ceram.x universal, Dentsply Sirona). Daily brushing and acid exposure were simulated using a brushing apparatus and a solution of 0.5 vol% citric acid. Microhardness, surface roughness, and substance loss were measured at baseline and after simulation of 1 and 3 years of function. All materials showed a decrease in microhardness after 3 years and an increase in surface roughness (Ra) after 1 and 3 years. The Ra increase was statistically significantly lower for the resin-matrix ceramics than for feldspar ceramic and similar to composite material. After 3 years, only feldspar ceramic showed no significant substance loss. In conclusion, resin-matrix ceramics demonstrate reduced roughening compared to feldspar ceramics, potentially improving restoration longevity by preventing plaque buildup, but differences in abrasion resistance suggest the need for further material-specific research. Future research should aim to replicate clinical conditions closely and to transition to in vivo trials.

Hemoglobin Protects Enamel against Intrinsic Enamel Erosive Demineralization.

INTRODUCTION: This study investigated the changes in the acquired enamel pellicle (AEP) proteome when this integument is formed in vivo after treatment with sugarcane-derived cystatin (CaneCPI-5), hemoglobin (HB), and a statherin-derived peptide (StN15), or their combination and then exposed to an intrinsic acid challenge. The effectiveness of these treatments in preventing intrinsic erosion was also evaluated. METHODS: Ten volunteers, after prophylaxis, in 5 crossover phases, rinsed with the following solutions (10 mL, 1 min): control (deionized water-H2O) - group 1, 0.1 mg/mL CaneCPI-5 - group 2, 1.0 mg/mL HB - group 3, 1.88 × 10-5M StN15 - group 4, or a blend of these - group 5. Following this, AEP formation occurred (2 h) and an enamel biopsy (10 µL, 0.01 m HCl, pH 2.0, 10 s) was conducted on one incisor. The biopsy acid was then analyzed for calcium (Arsenazo method). The vestibular surfaces of the other teeth were treated with the same acid. Acid-resistant proteins in the residual AEP were then collected and analyzed quantitatively via proteomics. RESULTS: Compared to control, treatment with the proteins/peptide, mixed or isolated, markedly enhanced acid-resistant proteins in the AEP. Notable increases occurred in pyruvate kinase PKM (11-fold, CaneCPI-5), immunoglobulins and submaxillary gland androgen-regulated protein 3B (4-fold, StN15), Hb, and lysozyme C (2-fold, StN15). Additionally, a range of proteins not commonly identified in the AEP but known to bind calcium or other proteins were identified in groups treated with the tested proteins/peptide either in isolation or as a mixture. The mean (SD, mM) calcium concentrations released from enamel were 3.67 ± 1.48a, 3.11 ± 0.72a, 1.94 ± 0.57b, 2.37 ± 0.90a, and 2.38 ± 0.45a for groups 1-5, respectively (RM-ANOVA/Tukey, p < 0.05). CONCLUSIONS: Our findings demonstrate that all treatments, whether using a combination of proteins/peptides or in isolation, enhanced acid-resistant proteins in the AEP. However, only HB showed effectiveness in protecting against intrinsic erosive demineralization. These results pave the way for innovative preventive methods against intrinsic erosion, using "acquired pellicle engineering" techniques.

Should We Wait to Brush Our Teeth? A Scoping Review Regarding Dental Caries and Erosive Tooth Wear.

BACKGROUND: Tooth brushing is a universal recommendation. However, the recommendations related to the time of its execution are conflicting, especially when dealing with patients at risk of erosive tooth wear (ETW) or dental caries. SUMMARY: Our objective was to summarize the evidence on the timing of brushing with fluoridated toothpaste in relation to ETW and cariogenic dietary challenges. We conducted a scoping review following the PRISMA-ScR checklist, using three databases searching for in vivo, in situ, or in vitro studies involving human teeth exposed to either a cariogenic or an erosive challenge. Only models including human saliva and fluoride were assessed. Data selection, extraction, and risk of bias analysis were done in duplicate and independently. From 1,545 identified studies, 17 (16 related to ETW and 1 to dental caries) were included. Most evidence (n = 10) supported that brushing with a fluoride-containing product does not increase ETW, independent of the moment of brushing. Delaying tooth brushing up to 1 h (n = 4) or individualized recommendations based on the patient's problem (n = 2) were less frequent. Only one study reported that brushing pre- or post-meal does not affect Streptococcus mutans counts. Most data were in situ (n = 13), and the overall study quality was judged as sufficient/low risk of bias. KEY MESSAGES: Although the available evidence lacked robust clinical studies, tooth brushing using fluoridated products immediately after an erosive challenge does not increase the risk of ETW and can be recommended, which is in line with recommendations for dental caries prevention. Furthermore, we suggest updating the international guidelines to promote individualized recommendations based on risk factors to prevent either ETW or dental caries.

Effectiveness of optical treatment in amblyopia and validation of measuring spectacle compliance with the ODM.

PURPOSE: The improvement in visual acuity (VA) was determined during optical treatment in children with amblyopia before their participation in a randomised clinical trial comparing the effect of dichoptic video gaming using virtual reality goggles with occlusion therapy. METHODS: Children aged 4-12 years with an interocular VA difference ≥0.20 logMAR and an amblyogenic factor: strabismus <30Δ, ≥1.00 D anisometropia, astigmatism ≥1.50 D and/or hypermetropia ≥1.50 D were eligible for 16 weeks of optical treatment. Children with previous amblyopia treatment were excluded. Compliance with spectacle wear was measured electronically over 1 week using the occlusion dose monitor (ODM). The reliability of these measurements was verified. The main outcome was an increase in amblyopic eye VA from baseline to 16 weeks. RESULTS: Sixty-five children entered the optical treatment period. Mean age was 6.0 ± 2.2 years (range: 4-12 years; IQR 4.5-6.7 years). Amblyopia was caused by anisometropia in 53 (82%) children, strabismus in 6 (9%) and combined mechanism in 6 (9%). After optical treatment, mean VA improved by 0.20 logMAR (SD 0.28; p < 0.001) and 0.07 in the amblyopic and fellow eye, respectively (SD 0.20; p = 0.03). This resulted in 24 children (37%) with an interocular VA difference <0.20 logMAR and in 17% of children with VA at the start of 0.30 logMAR or worse. Poor VA in the amblyopic eye at baseline (p = 0.001) and high anisometropia (p = 0.001) were associated with VA improvement. On average, spectacles were worn 9.7 ± 2.4 h/day (range: 2.3-13.6 h); mean compliance was 73% ± 18% of estimated wake time. Only ambient temperature ≥ 31°C or when spectacles were worn on top of the head prevented a reliable ODM measurement. CONCLUSIONS: VA improved by two lines resulting in more than a third of the children being treated sufficiently with spectacles alone and no longer being classified as amblyopic. The ODM proved to be a reliable method of measuring compliance with spectacle wear.

Stubby versus stabby: A preliminary analysis of canine microwear in primates: Implication for inferring ingestive behaviors.

Molar and incisor microwear reflect aspects of food choice and ingestive behaviors in living primates and have both been used to infer the same for fossil samples. Canine microwear, however, has received less attention, perhaps because of the prominent role canines play in social display and because they are used as weapons-while outside of a few specialized cases, their involvement in diet related behaviors has not been obvious. Here, we posit that microwear can also provide glimpses into canine tooth use in ingestion. Canines of Sumatran long-tailed macaques (Macaca fascicularis), agile gibbons (Hylobates agilis), lar gibbons (Hylobates lar), Thomas' leaf monkeys (Presbytis thomasi), and orangutans (Pongo abelii), and two African great apes, bonobos (Pan paniscus) and common chimpanzees (Pan troglodytes schweinfurthii), were considered. The labial tips of maxillary canine replicas were scanned using a white-light confocal profiler, and both feature and texture analyses were used to characterize microwear surface patterning. The taxa exhibited significant differences in canine microwear. In some cases, these were consistent with variation in reported anterior tooth use such that, for example, the orangutans, known to use their front teeth extensively in ingestion, had the highest median number of microwear features on their canines, whereas the gibbons, reported to use their front teeth infrequently in food acquisition, had the lowest.

Ultrasound assessment of synovitis in total knee replacements: concordance with MR imaging and joint aspiration.

OBJECTIVE: To determine if diagnostic ultrasound can reliably distinguish between synovial patterns of prosthetic joint infection and polymeric wear in total knee replacements. METHODS AND METHODS: This retrospective study was approved by our hospital IRB. Using the radiology report database, MR examinations performed within a week of diagnostic ultrasound and/or ultrasound-guided aspiration were identified. This yielded (1) 24 cases with MR and ultrasound comparisons; (2) 44 cases with MR, ultrasound, and aspiration comparisons; and (3) 92 cases with ultrasound and aspiration comparisons. The MR studies were reviewed by a musculoskeletal radiologist. The ultrasound studies were each reviewed by 2 other musculoskeletal radiologists. Each study was graded for synovial pattern indicating infection, polymeric wear, or normal/nonspecific. Agreement between the MR grader and the ultrasound graders as well as ultrasound inter-rater agreement were assessed using k statistics. Sensitivity, specificity, positive predictive value, and negative predictive value of ultrasound were calculated. RESULTS: Agreement between ultrasound and MR imaging was fair to moderate: k of 0.27 (95% CI: 0.04, 0.50) and 0.44 (95% CI: 0.23, 0.65) for ultrasound raters 1 and 2, respectively. Inter-rater agreement between ultrasound graders 1 and 2 was moderate, with k of 0.56 (95% CI: 0.42, 0.70). Ultrasound sensitivities for infection were 0.13 and 0.09, while specificities were 0.94 and 0.98. Ultrasound sensitivities for polymeric wear were 0.38 and 0.62 with specificities of 0.90 and 0.76. CONCLUSION: Ultrasound does not perform well in distinguishing patterns of synovitis either compared to MRI or a reference standard of aspiration/clinical follow-up.

Quality of Patient-Centered eHealth Information on Erosive Tooth Wear: Systematic Search and Evaluation of Websites and YouTube Videos.

BACKGROUND: Due to the declining prevalence of dental caries, noncarious tooth defects such as erosive tooth wear have gained increased attention over the past decades. While patients more frequently search the internet for health-related information, the quality of patient-centered, web-based health information on erosive tooth wear is currently unknown. OBJECTIVE: This study aimed to assess the quality of patient-centered, web-based health information (websites and YouTube videos) on erosive tooth wear. METHODS: German-language websites were systematically identified through 3 electronic search engines (google.de, bing.de or yahoo.de, and duckduckgo.com) in September 2021. Eligible websites were independently assessed for (1) technical and functional aspects via the LIDA instrument, (2) readability via the Flesch reading-ease score, (3) comprehensiveness of information via a structured checklist, and (4) generic quality and risk of bias via the DISCERN instrument by 2 different reviewers. An overall quality score (ie, higher scores being favored) generated from all 4 domains was used as the primary outcome. Quality scores from each domain were separately analyzed as secondary outcomes and compared by the Friedman test. The effect of practice-specific variables on quality scores of websites from private dental offices was assessed using generalized linear modeling. Eligible YouTube videos were judged based on (1) the comprehensiveness of information, (2) viewers' interaction, and (3) viewing rate. The comprehensiveness of information was compared between websites and YouTube videos using the Wilcoxon rank-sum test. RESULTS: Overall, 231 eligible websites and 7 YouTube videos were identified and assessed. The median overall quality of the websites was 33.6% (IQR 29.8%-39.2%). Secondary outcome scores amounted to 64.3% (IQR 59.8%-69.0%) for technical and functional aspects, 40.0% (IQR 34.0%-49.0%) for readability, 11.5% (IQR 3.9%-26.9%) for comprehensiveness of information, and 16.7% (IQR 8.3%-23.3%) for generic quality. While the comprehensiveness of information and generic quality received low scores, technical and functional aspects as well as readability resulted in higher scores (both Padjusted<.001). Regarding practice-specific variables, websites from private dental offices outside Germany (P=.04; B=-6.64, 95% CI -12.85 to -0.42) or from dentists who are a dental society member (P=.049; B=-3.55, 95% CI -7.09 to -0.01) resulted in lower readability scores (ie, were more difficult to read), while a shorter time since dentists' examination resulted in higher readability scores (P=.01; B=0.24 per year, 95% CI 0.05-0.43). The comprehensiveness of information from YouTube videos was 34.6% (IQR 13.5%-38.5%). However, the comprehensiveness of information did not vary between websites and YouTube videos (P=.09). Additionally, viewers' interaction (1.7%, IQR 0.7%-3.4%) and viewing rates (101%, IQR 54.6%-112.6%) were low. CONCLUSIONS: The quality of German-language, patient-centered, web-based information on erosive tooth wear was limited. Especially, the comprehensiveness and trustworthiness of the available information were insufficient. Web-based information on erosive tooth wear requires improvement to inform patients comprehensively and reliably.