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The phenomenon of orthodontic anchorage miniscrews loosening after being implanted several times happens in daily clinical practice, and the reasons need to be traced. This study aimed to investigate the underlying risk factors influencing the progressive susceptibility of orthodontic miniscrews to failure.Overall, 889 miniscrews were successively inserted into 347 patients because some loosened or fell off once, twice, or more before achieving their purposes. The number of miniscrew failures (ie, once, twice, or more) was defined as progressive susceptibility to failure. The clinical indicators were assessed via univariate analysis, multicollinearity diagnosis, and Poisson log-linear regression model with stepwise calculation to screen out.The progressive susceptibility of miniscrews to failure was proved to be affected by the age of patients, the onset of force application, site of placement, and appliance type. Age and onset of force application presented a negative relationship with susceptibility. Miniscrews inserted in the palatal region appeared to be more stable than the forepart of the arch. In contrast, the retromaxillary and retromandibular areas obtained the lowest stability. The patients with fixed appliances were more unlikely to suffer progressive failure than removable appliances. In addition, the larger number of screws inserted in each patient, the greater probability of failure.Younger people with removable appliances that miniscrews inserted in the retromaxillary or retromandibular regions and earlier onsets of loading had a higher progressive susceptibility to loosening. Meanwhile, the failure rate was elevated with the increasing number of screws per patient received.

Temporomandibular disorder (TMD) remained a huge clinical challenge, with high prevalence but limited, unstable, and only palliative therapeutic methods available. As one of the most vulnerable sites implicated in TMD, the temporomandibular joint disc (TMJD) displayed a complicated microstructure, region-specific fibrocartilaginous distribution, and poor regenerative property, which all further hindered its functional regeneration. To address the problem, with versatile and relatively simple electrospinning (ELS) technique, our study successfully fabricated a biomimetic, three-dimensional poly (ϵ-caprolactone) (PCL)/polylactide (PLA)/carbon nanotubes (CNTs) disc scaffold, whose biconcave gross anatomy and regionally anisotropic microstructure recapitulating those of the native disc. As in vitro results validated the superior mechanical, bioactive, and regenerative properties of the biomimetic scaffolds with optimal CNTs reinforcement, we further performed in vivo experiments. After verifying its biocompatibility and ectopic fibrochondrogenicity in nude mice subcutaneous implantation models, the scaffolds guided disc regeneration and subchondral bone protection were also confirmed orthotopically in rabbits TMJD defected areas, implying the pivotal role of morphological cues in contact-guided tissue regeneration. In conclusion, our work represents a significant advancement in complex, inhomogeneous tissue engineering, providing promising clinical solutions to intractable TMD ailments. STATEMENT OF SIGNIFICANCE: Complex tissue regeneration remains a huge scientific and clinical challenge. Although frequently implicated in temporomandibular joint disorder (TMD), functional regeneration of injured temporomandibular joint disc (TMJD) is extremely hard to achieve, mainly because of the complex anatomy and microstructure with regionally variant, anisotropic fiber alignments in the native disc. In this study, we developed the biomimetic electrospun scaffold with optimal CNTs reinforcement and regionally anisotropic fiber orientations. The excellent mechanical and bioactive properties were confirmed both in vitro and in vivo, effectively promoting defected discs regeneration in rabbits. Besides demonstrating the crucial role of morphological biomimicry in tissue engineering, our work also presents a feasible clinical solution for complex tissue regeneration.

INTRODUCTION: This retrospective study aimed to quantify the impact of coronavirus disease 2019 (COVID-19) on the orthodontic appointment and make an analysis of orthodontic emergencies (OEs) that occurred during the pandemic. METHODS: A total of 628 patients were randomly sampled from 3489 subjects who were undergoing active orthodontic treatment with fixed appliances, and the medical records were reviewed. OE occurrence was analyzed from 617 patients who had explicit return-visit records after the COVID-19 outbreak. Wilcoxon signed rank tests, chi-square tests, and a binary logistic regression were performed. RESULTS: The return-visit of 98.6% of the patients was delayed significantly with an increase over 8.98 ± 4.76 weeks (P

In this study, we used CFD-DEM model to simulate glucose gasification in a supercritical water fluidized bed reactor (SCWFBR). Simplified reaction kinetic model, including glucose decomposition, water gas shift reaction and methanation reaction, was used. Particle distributions, gas composition and reaction rate profiles were analyzed. Moreover, the influence of chemical reaction on flow behavior, and the effects of operation parameters, such as wall temperature, flow rates and initial bed height were investigated. The results show that high wall temperature, low flow rate and high initial bed height are in favor of gasification. However, lower H 2 yield, gasification efficiency (GE) are found at flow rate below the minimum fluidization velocity. The simulation results show good agreement with the experimental results, demonstrating the validity of this model. The information obtained by the numerical study is useful for the operation and optimization of the gasification reactor.

Although impacted or supernumerary teeth are common, multiple impacted teeth combined with supernumerary teeth is a rare condition, often found in association with syndromes such as cleidocranial dysplasia or Gardner's syndrome. This report presents two patients, a son and his mother, with multiple impacted and supernumerary teeth but no associated syndromes. The 27-year-old patient had 23 impacted teeth and 9 supernumerary teeth with maxillary osteoma. The patient's mother, 55 years old, had 14 impacted teeth and 6 supernumerary teeth with 16 hypodontial teeth.

Objectives The aim of this study was to evaluate the osseointegration of loaded orthodontic microscrews at different cortical bone thickness (CBT) sites. Study Design Forty-eight microscrews were inserted bilaterally in the tibias of 12 beagles, and divided into thick and thin CBT group. After 1, 3, 5, and 7 weeks, the dogs were killed and bone-screw specimens prepared for polyfluorochrome sequential labeling, microscopic computerized tomography (μCT) analysis, and biomechanical pull-out testing. Results All μCT parameters were increased in the thin CBT group, and decreased in the thick CBT group with time passed. F max of microscrews in thick CBT sites reached a peak in week 1, but dropped to lowest levels in week 3. Remodeling, apposition, and measured deposition areas of 3 labels were significantly higher in the thin CBT group than in the thick CBT group ( P Conclusions Relatively larger CBT is of benefit for primary stability at early time points, whereas thinner CBT is more appropriate for achieving long-term stability with prolonged time.

In this paper, an image segmentation method is proposed that integrates fuzzy 2-partition into Yen’s maximum correlation thresholding method. A fuzzy 2-partition of the image is obtained by transforming the image into fuzzy domain by means of two parameterized membership functions. Fuzzy correlation is defined to measure the appropriateness of the fuzzy 2-partition. An ideal threshold is calculated from the optimal membership functions’ parameters, which make the corresponding fuzzy 2-partition have maximum fuzzy correlation. In the process of searching the optimal parameters of membership functions, a fast recursive algorithm is presented in order to reduce the computation complexity. Experimental results on synthetic image, brain magnetic resonance (MR) images and casting images show that the proposed method has a satisfactory performance.

Purpose During orthodontic treatment and chronic periodontitis, the periodontal vasculature is severely impaired by overloaded mechanical force or chronic inflammation. This leads to the hypoxic milieu of the periodontal stem cell niche and ultimately affects periodontal tissue remodelling. However, the role of hypoxia in the regulation of periodontal ligament stem cell (PDLSC) behaviours still remains to be elucidated. The present study was aimed at investigating the effects of hypoxia on osteogenic differentiation, mineralisation and paracrine release of PDLSCs and further demonstrating the involvement of mitogen-activated protein kinase (MAPK) signalling in the process. Methods First, PDLSCs were isolated and characterised. Second, the effects of different periods of hypoxia on PDLSC osteogenic potential, mineralisation and paracrine release were investigated. Third, extracellular signal-regulated kinases 1 and 2 (ERK1/2) and p38 kinase activities under hypoxia were measured. Finally, specific MAPK inhibitors PD98059 and SB203580 were employed to investigate the involvement of two kinases in PDLSC osteogenesis under hypoxia. Results Immunocytochemical staining and multilineage differentiation assays verified that the isolated cells were PDLSCs. Cell viability, alkaline phosphatase (ALP) activity, messenger RNA (mRNA) and protein levels of runt-related transcription factor 2 (Runx2) and Sp7, mineralisation and prostaglandin E2 (PGE2) and vascular endothelial growth factor (VEGF) release were significantly increased by hypoxia. ERK1/2 and p38 were activated in different ways under hypoxia. Furthermore, hypoxia-stimulated transcription and expression of the above-mentioned osteogenic regulators were also reversed by PD98059 and SB203580 to different degrees. Conclusions Exposure of PDLSCs to hypoxia affected their osteogenic potential, mineralisation and paracrine release, and the process involved mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (MEK/ERK) and p38 MAPK signalling.

Harmful cyanobacterial blooms and their negative impacts on water ecosystems and human health have been reported all over the world, and Microcystis aeruginosa is one of the most dominant and ecologically damaging species in eutrophic lakes such as Dianchi Lake and Taihu Lake in China. Although physical or chemical control of the blooms is possible in short period, these methods could cause other problems. Thus, there is still a need for research on biological factors controlling cyanobacteria blooms. We screened part of the Yunnan University actinomycete strain library and found that the extract of Streptomyces hebeiensis YIM 001 T exhibited obvious inhibition on M. aeruginosa . The main component – nanaomycin A methyl ester (NAME) was isolated at a level of 20 mg L −1 by scale-up fermentation. Lytic mechanism experiments of NAME on M. aeruginosa demonstrated it could effectively inhibit the growth of M. aeruginosa (EC 50 at 72 h = 2.97 mg L −1 ), hinder cell division and enlarge cell size. NAME damaged M. aeruginosa cells as evidenced by decreases in algal activity, biomass, esterase activity and chlorophyll- a content. The SOD activity of the treated cells initially increased, and then decreased together with a gradual increase in both O 2 − and malondialdehyde (MDA) content, consistent with inhibitory effects of NAME due to lipid peroxidation damage of the algal cell membrane. The results suggest that NAME is effective for controlling undesired cyanobacteria and the Chl -fluorescence is a potential endpoint to assay the NAME eco-toxicity on cyanobacteria.

OBJECTIVE: The aim of this study was to evaluate the effect of different healing times on the stability of titanium mini-implants used for orthodontic anchorage. STUDY DESIGN: Eight male beagles were used and randomized into 4 groups according to different healing times (1, 3, 5, and 7 weeks); each group had 2 beagles. Sixty-four mini-implants were inserted bilaterally in the maxilla and mandible of the beagles. Microscopic computerized tomography (μCT) and pull-out test were used for morphometric and biomechanical analysis, respectively. RESULTS: All μCT parameters and F(max) (maximum pull-out force) increased with the prolongation of healing time. One week after insertion, all 4 measurements, namely osseointegration, trabecular bone volume density, intersection surface, and F(max), were lower in the maxilla group than in the mandible group (P < .05). Between the span of 1 and 3 weeks after insertion, a more obvious rising tendency of the 4 values was observed in the maxilla group than in the mandible group. Five and 7 weeks after insertion, the maxilla group expressed higher values of the 4 measurements than the mandible group (P < .05). CONCLUSIONS: Although insertion in the mandible could provide higher primary stability for mini-implants, with the prolongation of healing time, insertion in the maxilla achieves higher osseointegration. The results indicated that insertion in maxilla has a more positive effect on the stability of mini-implants than insertion in the mandible.

Introduction The aim of this study was to evaluate the impact of the placement angle on the stability of loaded microscrews. Methods Forty-eight microscrews were placed at 4 angles ( 30°, 50°, 70°, and 90°) into the tibiae of 12 beagles, loaded with a force of 2 N immediately, and maintained for 8 weeks. Microcomputed tomography and pullout tests were used for morphometric and biomechanical analyses, respectively. Results All microcomputed tomography parameters and the peak loads at extraction of the microscrews were influenced by the placement angles of the microscrews. The higher microcomputed tomography parameters and the peak load at extraction were measured at angles from 50° to 70°. Oblique and vertical placement angles resulted in reduced stability of the loaded microscrews ( P Conclusions To achieve the best stability of microscrews, a placement angle of 50° to 70° is advisable.

Objective The aim of this study was to evaluate the influence of different healing times before loading on the stability of implanted titanium mini-implant. Study design Forty mini-implants were implanted in bilateral maxilla in 10 beagles, loaded with a force of 0.98 N after a delay of 0 day (immediately activated) and 1, 3, 5, and 7 weeks. Microscopic computerized tomography (μCT) and pullout test were used for morphometric and biomechanical analyses, respectively. Results All μCT parameters and the Fmax of mini-implants were stimulated with the prolongation of healing time before loading. Between the group of 1 week and 3 weeks, a more obvious rising tendency of both μCT parameters and the Fmax of implants was observed. After 3 weeks, the tendency of increase tapered off. Conclusion The results indicated that early loading may decrease osseointegration of mini-implants.