Comparison between the designed and achieved mesiodistal angulation of maxillary canines and posterior teeth and influencing factors: First premolar extraction treatment with clear aligners.

INTRODUCTION: This study aimed to compare the designed and achieved mesiodistal angulation of maxillary canines and posterior teeth (MCPT) for first premolar extraction with clear aligner treatment and identify the main influencing factors for preventing MCPT tipping toward the extraction space. METHODS: A total of 21 adults with first premolar extraction were recruited. The designed and achieved tooth movement of MCPT was measured by superimposing their respective pretreatment and posttreatment cone-beam computed tomography images and compared with the designed tooth movement in ClinCheck using the paired t test and scatter plot analysis. Influencing factors, including dental arch length change, canine distalization, and initial mesiodistal angulation, were analyzed using the linear mixed-effect model. RESULTS: Designed distal crown tipping (second premolar, 10.73 ± 3.22°; first molar, 9.83 ± 3.60°; second molar, 7.18 ± 2.36°) significantly increased the distal inclination of the second premolar (2.50° ± 5.15°; P ï¼œ0.001), first molar (1.07° ± 4.14°; P ï¼œ0.001), and second (0.70° ± 3.78°; P ï¼œ0.001). Furthermore, mesial tipping (8.59° ± 6.03°; P ï¼œ0.001) achieved appropriate distal crown tipping of canines (-6.43° ± 5.04°; P ï¼œ0.001). The implemented preliminary formulas showed that shortening of the dental arch length, the distance of canine distalization, and initial mesiodistal angulation were closely related to the antitipping design. CONCLUSIONS: Designed distal crown tipping of posterior teeth and mesial crown tipping of canines might prevent unwanted crown tipping toward the extraction space during space closure. The proposed preliminary formula could guide antitipping designs in clear aligner treatment.

Microplastics in Small Waterbodies and Tadpoles from Yangtze River Delta, China.

Although microplastic (MP) pollution in freshwater systems is gaining attention, our knowledge of its distribution in small waterbodies is scarce. Small waterbodies are freshwater habitats to many species, including amphibians, that are vulnerable to MP pollution. This study analyzed the distribution and characteristics of MPs in 25 small waterbodies from the Yangtze River Delta, China. MPs were detected in surface water, sediment, and tadpoles with abundances ranging from 0.48 to 21.52 items L-1, 35.76 to 3185.33 items kg-1, and 0 to 2.73 items individual-1 (0 to 168.48 items g-1), respectively. The dominant shape and polymer of MPs in water and tadpole samples were polyester (PES) fibers, and polypropylene (PP) fibers and fragments were dominant in sediment samples. In addition, MPs were primarily <0.5 mm in length in all samples. Tadpole length was positively correlated to the number of MPs detected. The abundance, shape, and polymer distribution of MPs in tadpoles resembled that of water rather than sediment, suggesting that tadpoles likely take up MPs from the surrounding water. This study demonstrated that MPs are abundant in these small waterbodies and are ingested by resident tadpoles. This may suggest a pathway of MP entry into aquatic and terrestrial food webs.

Mutation in SSUH2 Causes Autosomal-Dominant Dentin Dysplasia Type I.

Dentin dysplasia type I (DDI) is an autosomal-dominant genetic disorder resulting from dentin defects. The molecular basis of DDI remains unclear. DDI exhibits unique characteristics with phenotypes featuring obliteration of pulp chambers and diminutive root, thus providing a useful model for understanding the genetics of tooth formation. Using a large Chinese family with 14 DDI patients, we mapped the gene locus responsible for DDI to 3p26.1-3p24.3 and further identified a missense mutation, c.353C>A (p.P118Q) in the SSUH2 gene on 3p26.1, which co-segregated with DDI. We showed that SSUH2 (p.P118Q) perturbed the structure and significantly reduced levels of mutant (MT) protein and mRNA compared with wild-type SSUH2. Furthermore, MT P141Q knock-in mice (+/- and -/-) had a unique partial obliteration of the pulp cavity and upregulation or downregulation of six major genes involved in odontogenesis: Dspp, Dmp1, Runx2, Pax9, Bmp2, and Dlx2. The phenotype of missing teeth was determined in zebrafish with morpholino gene knockdowns and rescued by injection of normal human mRNA. Taken together, our observations demonstrate that SSUH2 disrupts dental formation and that this novel gene, together with other odontogenesis genes, is involved in tooth development.

A splicing mutation in VPS4B causes dentin dysplasia I.

BACKGROUND: Dentin dysplasia I (DDI) is a genetically heterogeneous autosomal-dominant disorder characterised by rootless teeth with abnormal pulpal morphology, the aetiology of which presents as genetically heterogeneous. METHODS AND RESULTS: Using a cohort of a large Chinese family with 10 patients with DDI, we mapped to a 9.63 Mb candidate region for DDI on chromosome 18q21.2-q21.33. We then identified a mutation IVS7+46C>G which resulted in a novel donor splice site in intron 7 of the VPS4B gene with co-segregation of all 10 affected individuals in this family. The aberrant transcripts encompassing a new insert of 45 bp in size were detected in gingival cells from affected individuals. Protein structure prediction showed that a 15-amino acid insertion altered the ATP-binding cassette of VPS4B. The mutation resulted in significantly reduced expression of mRNA and protein and altered subcellular localisation of VPS4B, indicating a loss of function of VPS4B. Using human gingival fibroblasts, the VPS4B gene was found to act as an upstream transducer linked to Wnt/ß-catenin signalling and regulating odontogenesis. Furthermore, knockdown of vps4b in zebrafish recapitulated the reduction of tooth size and absence of teeth similar to the tooth phenotype exhibited in DDI index cases, and the zebrafish mutant phenotype could be partially rescued by wild-type human VPS4B mRNA. We also observed that vps4b depletion in the zebrafish negatively regulates the expression of some major genes involved in odontogenesis. CONCLUSIONS: This study identifies VPS4B as a disease-causing gene for DDI, which is one of the important contributors to tooth formation, through the Wnt/ß-catenin signalling pathway.

Phthalocyanine blue leaching and exposure effects on Microcystis aeruginosa (cyanobacteria) of photoaged microplastics.

Light-stabilizing additives may contribute to the overall pollution load of microplastics (MPs) and potentially enter the food chain, severely threatening aquatic life and human health. This study investigated the variation between polystyrene (PS) MPs and phthalocyanine blue (CuPC)-containing MPs before and after photoaging, as well as their effects on Microcystis aeruginosa. The presence of PS-MPs increased cell mortality, antioxidant enzyme activity, and the variation in extracellular components, while the presence of CuPC exacerbated these variations. CuPC-containing MPs caused different increasing trends in superoxide dismutase and malondialdehyde activities due to electron transfer across the membrane. Transcriptomic analysis revealed that the MPs and CuPC affected various cellular processes, with the greatest impact being on cell membranes. Compared with MPs, CuPC negatively affected ribosome and polysaccharide formation. These findings provide insights into the molecular mechanisms underlying the cellular response to MPs and their associated light-stabilizer pollution and imply the necessity for mitigating the pollution of both MPs and light-stabilizers.

Rapid photo aging of commercial conventional and biodegradable plastic bags.

Biodegradable plastic (BPs) bags are introduced and widely used as alternatives to conventional commercial plastic bags in an effort to mitigate the adverse impacts of nondegradable (conventional) plastics. However, being used as packaging, the stability and safeness of the BPs and even the conventional plastics with photo irradiation in short duration remain unknown. In this study, we systematically explored the photo aging of commercial BPs bags and conventional plastic bags in film forms in both outdoor and laboratory experiments in short duration (~ one month) under the scenario of ordinary daily use. Conventional plastic bags (polyethylene (PE)) and BPs bags (hybrids of polylatic acid (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) with additives (Magadiite or Starch)) were investigated. In contrast with the visually negligible surface change of PE films in both outdoor and laboratory environments, obvious surface alteration as surface deterioration with cracks and holes was obtained for BPs from SEM images in direct irradiation by both natural and simulated sunlight. Consistently, AFM results also indicated that the surface of BPs had the tendency to be rougher after photo aging process. Further FTIR and XPS results demonstrated that though the visual surface alteration of conventional and biodegradable plastics are distinct, the mechanisms dominating the change of C-H/C-C bonds to carbon­oxygen functional groups (i.e., C-O/C=O/O-C=O) for both conventional plastics and BPs during the photo aging process are similar. Moreover, tensile strength tests demonstrated that BPs bags being easily broken compared with the conventional PE bags might attribute to the difference in their mechanical properties. The findings of this study suggest that the potential risk of MPs and NPs released from the BPs bags via photo aging process are great new threats to natural environment and even human health.

Accumulation of microplastics in tadpoles from different functional zones in Hangzhou Great Bay Area, China: Relation to growth stage and feeding habits.

Microplastics (MPs) are ubiquitous in freshwater ecosystems, including inland small waterbodies (e.g., ponds and ditches), which are unique habitats for tadpoles. The uptake of MPs by tadpoles is influenced by their habitat, life stage, and feeding strategy. In this study, we investigated MP levels in small waterbodies in three different functional zones from the Hangzhou Great Bay Area, China, and resident tadpoles at different stages of metamorphosis with different feeding habits. Our results indicated that MPs in all three sampling areas were predominantly fibers; and the highest abundances of MPs were observed in water (4.70 ± 2.30 items/L) and sediment (728 ± 324 items/kg) from a textile industrial area, likely the result of nearby human activities. There was no significant difference in MP number in tadpoles between areas; however, omnivorous tadpoles with labial teeth and horny beaks ingested more MPs than did filter feeders. Based on their developmental characteristics, the collected tadpoles were categorized as: pre-metamorphosis, pro-metamorphosis, and metamorphic climax. The MP levels exhibited an upward trend, and MP size gradually increased as tadpole development progressed. This suggests that MPs may accumulate in tadpoles as they grow and potentially affect their metamorphosis from larvae to frogs.

Microplastics distribution in different habitats of Ximen Island and the trapping effect of blue carbon habitats on microplastics.

Sediments are considered to be important sinks of microplastics, but the enrichment process of microplastics by blue carbon ecosystems is poorly studied. This study analyzed the spatial distribution and temporal changes, assessed the polymer types and morphological characteristics of microplastics in sediments of five ecosystems, i.e. forests, paddy fields, mangroves, saltmarshes and bare beaches on Ximen Island, Yueqing Bay, China. The trapping effect of blue carbon (mangrove and saltmarsh) sediments on microplastic was further explored. Temporal trends in microplastic abundance showed a significant increase over the last 20 years, with the enrichment of microplastics in mangrove and saltmarsh sediments being 1.7 times as high as that in bare beach, exhibiting blue carbon vegetations have strong enrichment effect on microplastics. The dominant color, shape, size, and polymer type of microplastics in sediments were transparent, fibers and fragments, <1 mm, and polyethylene, respectively. Significant differences in the abundance and characteristics of microplastics between intertidal sediments and terrestrial soils reveal that runoff input is the main source of microplastics. This study provided the evidence of blue carbon habitats as traps of microplastics.

Microplastics generated under simulated fire scenarios: Characteristics, antimony leaching, and toxicity.

Intentional or incidental thermal changes inevitably occur during the lifecycle of plastics. High temperatures accelerate the aging of plastics and promote their fragmentation to microplastics (MPs). However, there is little information available on the release of MPs after fires. In this study, an atomic force microscope combined with nanoscale infrared analysis was used to demonstrate the physicochemical properties of polypropylene (PP) plastics under simulated fire scenarios. Results showed that the chemical composition and relative stiffness of heat-treated plastic surfaces changed, significantly enhancing the generation of MPs under external forces; over (2.1 ± 0.2) × 105 items/kg abundance of MPs released from PP which were burned at 250 °C in air and trampled by a person. The leaching of antimony (Sb) from MPs in different solutions first increased and then decreased with increasing temperature, reaching a maximum at 250 °C. Higher concentrations of humic acid (10 vs 1 mg/L) caused a greater release of Sb. Furthermore, the tap water leachates of PP burned at 250 °C had the greatest effect on the growth and photosynthetic activity of Microcystis aeruginosa. Our results suggest fires as a potential source of MPs and calls for increased focus on burning plastics in future research.

Co(III)-Salen immobilized cellulose nanocrystals for efficient catalytic CO2 fixation into cyclic carbonates under mild conditions.

Searching for green, recyclable and highly efficient catalyst for the synthesis of cyclic carbonates from CO2 is of great importance because it is profitable for reducing the greenhouse effects and meets the principles of green chemistry. Herein, a series of cellulose nanocrystals, either the pristine or modified ones (TEMPO oxidized and Co(III)salen immobilized), were explored as catalysts for cycloaddition of epoxides and carbon dioxide. The impact of surface properties on the performance of the as-made catalysts was investigated. Co(III)-salen grafted cellulose nanocrystals was proven to be the most effective catalyst in this study, which could afford excellent yield up to 99 % after 24 h even under low CO2 pressures of 0.1 MPa. They can be easily recovered and reused for at least 4 times, demonstrating their excellent stability. We found that the surface functional groups such as enriched sulfate or carboxylic groups could also account for the enhanced catalytic activity. This work highlights the applications of green and sustainable nanoparticles in a cycloaddition reaction and offers a sustainable solution in industrial catalysis related to CO2 conversions.

Chronic microfiber exposure in adult Japanese medaka (Oryzias latipes).

Microplastic fibers (MFs) pollute aquatic habitats globally via sewage release, stormwater runoff, or atmospheric deposition. Of the synthetic MFs, polyester (PES) and polypropylene (PP) are the most common. Field studies show that fish ingest large quantities of MFs. However, few laboratory studies have addressed host responses, particularly at the organ and tissue levels. Adult Japanese medaka (Oryzias latipes), a laboratory model fish, were exposed to aqueous concentrations of PES or PP MFs (10,000 MFs/L) for 21 days. Medaka egested 1,367 ± 819 PES MFs (0.1 ± 0.04 mg) and 157 ± 105 PP MFs (1.4 ± 0.06 mg) per 24 hrs, with PP egestion increasing over time. Exposure did not result in changes in body condition, gonadosomatic- or hepatosomatic indices. PES exposure resulted in no reproductive changes, but females exposed to PP MFs produced more eggs over time. MF exposure did not affect embryonic mortality, development, or hatching. Scanning electron microscopy (SEM) of gills revealed denuding of epithelium on arches, fusion of primary lamellae, and increased mucus. Histologic sections revealed aneurysms in secondary lamellae, epithelial lifting, and swellings of inner opercular membrane that altered morphology of rostral most gill lamellae. SEM and histochemical analyses showed increased mucous cells and secretions on epithelium of foregut; however, overt abrasions with sloughing of cells were absent. For these reasons, increased focus at the tissue and cell levels proved necessary to appreciate toxicity associated with MFs.

Microplastic pollution in water and sediment in a textile industrial area.

Microplastics pollution in the environment is closely determined by the surrounding industrial and human activities. In present study, we investigated microplastics in water and sediment samples collected from a textile industrial area in Shaoxing city, China. The abundance of microplastics varied from 2.1 to 71.0 items/L in surface water samples, and from 16.7 to 1323.3 items/kg (dw) in sediment samples. The polymer type was dominated by polyester both in water (95%) and sediment (79%) samples. The majority of the detected microplastics was predominantly colored fibers smaller than 1 mm in diameter. The high level of microplastic pollution detected in local freshwater and sediment environments was attributed to the production and trading activities of textile industries, for which severe regulations should be envisaged in the future to effectively reduce the local microplastic pollution.

Effects of inorganic ions and natural organic matter on the aggregation of nanoplastics.

The aggregation of nanoplastics (NPs) is a key issue in understanding the dynamic nature of NPs in the environment. The aggregation of NPs under various environmental conditions has not yet been studied. We investigated the influences of inorganic ions and natural organic matter (NOM) on polystyrene (PS) NPs aggregation in solutions. Results showed that PS NPs remained stable in wide ionic strength solutions of NaCl (1-100 mM) and CaCl2 (0.1-15 mM), and only in low ionic strength FeCl3 solutions (0.01 mM). However, obvious PS NPs aggregation was observed in FeCl3 solutions with an increase in ionic strength (0.1 and 1 mM). Moreover, NOM had a negligible effect on PS NPs aggregation in all ionic strengths of NaCl and CaCl2 solutions and in low ionic strength FeCl3 solutions (0.01 mM). However, NOM reduced PS NPs aggregation in an intermediate ionic strength FeCl3 (0.1 mM) solution and increased aggregation in a high ionic strength FeCl3 (1 mM) solution. Based on the theoretical analysis of interaction forces among PS NPs, the Derjaguin-Landau-Verwey-Overbeek force was a contributor governing PS NPs aggregation either in the absence or presence of NOM. In addition, other factors, including electrostatic heterogeneity of PS NPs surfaces, steric repulsion induced by NOM, and clusters formed via bridging effect in the presence of NOM also contributed to altered PS NPs aggregation under selected conditions. The PS NPs-NOM clusters were directly observed using a cryogenic scanning electron microscope.

Clinician, dental student, and orthognathic patient perception of black-and-white silhouette lateral profile dimensions of ideal chin position in a Chinese population.

OBJECTIVES: This study aimed to investigate differences in the influence of chin prominence and length on perception of facial aesthetics by Chinese dental clinicians, orthognathic patients, and dental students. STUDY DESIGN: Male and female silhouette lateral profiles were modified to obtain 28 facial profiles by altering chin prominence and length by 3 mm in the sagittal and vertical planes. Images were rated by 70 clinicians, 30 orthognathic patients, and 100 dental students on a 7-point Likert scale. RESULTS: Perceived attractiveness was highest when the male chin prominence (MCP) was -3 mm to 3 mm and the female chin prominence (FCP) was 3 mm. In contrast, male chin length (MCL) of 0 to 3 mm and female chin length (FCL) of 0 mm were considered the most attractive. In the sagittal and vertical profiles, MCP (-9 mm), FCP (-9 mm), FCL (-9 mm), and MCL (-9 mm) were ranked least attractive. CONCLUSIONS: The overall aesthetic opinions of orthognathic patients, clinicians, and dental students are similar. The greater the retrusion or protrusion of the chin and the shorter or longer the chin length, the lower were the rates of facial aesthetics and the greater were the desire for surgery.

Linkages between the spatial toxicity of sediments and sediment dynamics in the Yangtze River Estuary and neighboring East China Sea.

Anthropogenic activities are driving an increase in sediment contamination in coastal areas. This poses significant challenges for the management of estuarine ecosystems and their adjacent seas worldwide. However, few studies have been conducted on how dynamic mechanisms affect the sediment toxicity in the estuarine environment. This study was designed to investigate the linkages between sediment toxicity and hydrodynamics in the Yangtze River Estuary (YRE) area. High sediment toxicity was found in the Yangtze River mouth (Region I), the depocenter of the Yangtze River Delta (Region II), and the southeastern area of the adjacent sea (Region III), while low sediment toxicity was found in the northeastern offshore region (Region IV). A spatial comparison analysis and regression model indicated that the distributed pattern of sediment toxicity was likely related to hydrodynamics and circumfluence in the East China Sea (ECS) shelf. Specifically, high sediment toxicity in Region I may be affected by the Yangtze River Pump (YRP) and the low hydrodynamics there, and high toxicity in Region II can be influenced by the low sediment dynamics and fine sediment in the depocenter. The high sediment toxicity in Region III might be related to the combination of the YRP and Taiwan Warm Current, while the low toxicity in Region IV may be influenced by the local coarse-grained relict sand with strong sediment dynamics there. The present research results further suggest that it is necessary to link hydrodynamics and the spatial behavior of sediment and sediment-derived pollutants when assessing the pollution status of estuarine environments, especially for those mega-estuaries and their neighboring ocean environments with complex waves, tides and ocean currents.

Uptake, accumulation and elimination of polystyrene microspheres in tadpoles of Xenopus tropicalis.

Microplastic is an emerging contaminant affecting freshwater and marine ecosystem across the globe. In the present study, the filter feeding tadpoles of Xenopus tropicalis were exposed to polystyrene microspheres (1 and 10 µm) for 48 h. Microspheres were observed in gills and digestive tract of tadpoles within 1 h after exposure as well as in feces 6 h after exposure. The accumulation of microspheres in the tadpoles were concentration dependent (Univariate ANOVA, p < 0.001), but no time dependent accumulation of microspheres was observed in tadpoles 48 h after exposure (Univariate ANOVA, p > 0.05). After the exposed tadpoles were transferred to clean water, the number of microspheres in the tadpoles decreased dramatically after 1 d and continued to decrease gradually afterwards. The absorbed polystyrene particles in unfed tadpoles was significantly higher than those in the fed tadpoles at 12 and 24 h after exposure. After transfer to clean water, the fed tadpoles showed a significant decrease in the amount of absorbed polystyrene particles, while the unfed tadpoles showed no significant change in the amount of absorbed polystyrene particles. Our results suggested that microspheres were likely to be ingested and egested relatively fast by tadpoles. Our results indicated that aquatic vertebrate organisms might ingest more microplastics if the abundance of microplastics continues to increase while the available food becomes less.

A novel small deletion mutation in RUNX2 gene in one Chinese family with cleidocranial dysplasia.

Cleidocranial dysplasia (CCD) is a skeletal dysplasia with autosomal-dominant inheritance. The runt related transcription factor 2 (RUNX2) gene is the only gene in which mutations are known to cause CCD. We report identification of a novel small deletions mutation in the RUNX2 gene in a Chinese family with CCD. A 29-year-old female was diagnosed as proband of CCD based on the clinical findings, which show delayed closure of the fontanels, hypoplastic or aplastic clavicles and dental anomalies. Similar dental and skeletal symptoms were also observed in the other three affected individuals. We prepared genomic DNA from all four affected individuals, unaffected individual from her family members, as well as 100 unrelated healthy controls. PCR was conducted using the above genomic DNA as template and the RUNX2 gene-specific primers. The PCR product was subjected to direct sequencing and the sequence was compared to that of RUNX2 gene within the NCBI database. We detected a small deletion CCTA from nucleotide 635 to nucleotide 638 in exon 3 of RUNX2 gene of the proband. This will lead to the introduction of a translational stop codon at codon 220, resulting in a truncated RUNX2 protein, and therefore within the runt domain of the RUNX2 protein. We detected the same mutation in the the other three affected individuals, and did not detect any mutation in the unaffected family members or the 100 unrelated healthy controls, demonstrating that this is a novel missense mutation in RUNX2 gene and therefore, contributes to the molecular diagnosis of CCD.