Coupled Poly(ethylenimine) Coreactant to Enhance Electrochemiluminescence of Polymer Dots for Array Imaging of Protein Biomarkers.

Traditional electrochemiluminescent (ECL) bioanalysis suffers from the demand for excessive external coreactants and the damage of reaction intermediates. In this work, a poly(ethylenimine) (PEI)-coupled ECL emitter was proposed by covalently coupling tertiary amine-rich PEI to polymer dots (Pdots). The coupled PEI might act as a highly efficient coreactant to enhance the ECL emission of Pdots through intramolecular electron transfer, reducing the electron transfer distance between emitter and coreactant intermediates and avoiding the disadvantages of traditional ECL systems. Through modification of the PEI-Pdots with tDNA, a sequence partially complementary to cDNA that was complementary to the aptamer of target protein biomarker (aDNA), tDNA-PEI-Pdots were obtained. The biosensors were produced using Au/indium tin oxide (ITO) with an aDNA/cDNA hybrid, and an ECL imaging biosensor array was constructed for ultrasensitive detection of protein biomarkers. Using vascular endothelial growth factor 165 (VEGF165) as a protein model, the proposed ECL imaging method containing two simple incubations with target samples and then tDNA-PEI-Pdots showed a detectable range of 1 pg mL-1 to 100 ng mL-1 and a detection limit of 0.71 pg mL-1, as well as excellent performance such as low toxicity, high sensitivity, excellent selectivity, good accuracy, and acceptable fabrication reproducibility. The PEI-coupled Pdots provide a new avenue for the design of ECL emitters and the application of ECL imaging in disease biomarker detection.

Tumor Microenvironment-Triggered Self-Adaptive Polymeric Photosensitizers for Enhanced Photodynamic Therapy.

Photodynamic therapy (PDT) employs photosensitizers to convert nearby oxygen into toxic singlet oxygen (1O2) upon laser light irradiation, showing great potential as a noninvasive approach for tumor ablation. However, the therapeutic efficacy of PDT is essentially impeded by π-π stacking and the aggregation of photosensitizers. Herein, we propose a tumor microenvironment-triggered self-adaptive nanoplatform to weaken the aggregation of photosensitizers by selenium-based oxidation at the tumor site. The selenide units in a selenium-based porphyrin-containing amphiphilic copolymer (PSe) could be oxidized into hydrophilic selenoxide units, leading to the nanoplatform self-expansion and stretching of the distance between intramolecular porphyrin units. This process could provide a better switch to greatly reduce the aggregation of photosensitive porphyrin units, generating more 1O2 upon laser irradiation. As verified in a series of in vitro and in vivo studies, PSe could be efficiently self-adapted at tumor sites, thus significantly enhancing the PDT therapeutic effect against solid tumors and minimizing side effects.

O2-Independent H2O2 Production via Water-Polymer Contact Electrification.

Hydrogen peroxide (H2O2), as a critical green chemical, has received immense attention in energy and environmental fields. The ability to produce H2O2 in earth-abundant water without relying on low solubility oxygen would be a sustainable and potentially economic process, applicable even to anaerobic microenvironments, such as groundwater treatment. However, the direct water to H2O2 process is currently hindered by low selectivity and low production rates. Herein, we report that poly(tetrafluoroethylene) (PTFE), a commonly used inert polymer, can act as an efficient triboelectric catalyst for H2O2 generation. For example, a high H2O2 production rate of 24.8 mmol gcat-1 h-1 at a dosage of 0.01 g/L PTFE was achieved under the condition of pure water, ambient atmosphere, and no sacrificial agents, which exceeds the performance of state-of-the-art aqueous H2O2 powder catalysts. Electron spin resonance and isotope experiments provide strong evidence that water-PTFE tribocatalysis can directly oxidize water to produce H2O2 under both anaerobic and aerobic conditions, albeit with different synthetic pathways. This study demonstrates a potential strategy for green and effective tribocatalytic H2O2 production that may be particularly useful toward environmental applications.

Solvent Content Controlling Strategy for Cocrystallizable Polyesters Enables a Stress-Free Two-Way Shape Memory Effect with Wider Service Temperatures.

It is challenging to enhance the stress-free two-way shape memory (stress-free TWSM) effect to obtain a wide range of response temperatures. Herein, a polycaprolactone (PCL)/poly(ω-pentadecalactone) (PPDL) is photocured under UV light irradiation in the solvent of 1,1,2-trichloroethane (TCA), to obtain a series of cross-linked polyesters (CPES). Controlling solvent content (SC) which is removed after the polymerization allows the yielded CPES to perform a regulatable thermodynamic and stress-free TWSM properties. High SC is beneficial to reduce the degree of chain overlap (C/C* ) of PPDL chain segments in the PCL-based CPES network, then causes the cocrystallization of PCL and PPDL and yielding an additional melting-transitions (Tm ). An enhanced stress-free TWSM is obtained in high SC samples (CPES-15-90), reflected in the attainment of a wide range of response temperature, which means a wider service temperature. The enhancement is reflected in higher reversible strain of high SC samples compared with the samples prepared with low SC when varying high trigger temperature (Thigh ). Even at high Thigh , the high SC sample still has reversible strain. Therefore, controlling SC strategy for photocuring copolyester not only provides a new preparation approach for high-performance shape memory (SM) polymers, but also offers new condensed polymer structure to explore.

Facile synthesis of lignin-based Fe-MOF for fast adsorption of methyl orange.

To rapidly remove dyes from wastewater, iron-based metal-organic frameworks modified with phenolated lignin (NH2-MIL@L) were prepared by a one-step hydrothermal method. Analyses of the chemical structure and adsorption mechanism of the NH2-MIL@L proved the successful introduction of lignin and the enhancement of its adsorption sites. Compared with NH2-MIL-101-Fe without phenolated lignin, the modification with lignin increased the methyl orange (MO) adsorption rate of NH2-MIL@L. For the best adsorbent, NH2-MIL@L4, the MO adsorption efficiency in MO solution reached 95.09% within 5 min. NH2-MIL@L4 reached adsorption equilibrium within 90 min, exhibiting an MO adsorption capacity of 195.31 mg/g. The process followed pseudo-second-order kinetics and the Dubinin-Radushkevich model. MO adsorption efficiency of NH2-MIL@L4 was maintained at 89.87% after six adsorption-desorption cycles. In mixed solutions of MO and methylene blue (MB), NH2-MIL@L4 achieved an MO adsorption of 94.02% at 5 min and reached MO adsorption equilibrium within 15 min with an MO adsorption capacity of 438.6 mg/g, while the MB adsorption equilibrium was established at 90 min with an MB adsorption rate and capacity of 95.60% and 481.34 mg/g, respectively. NH2-MIL@L4 sustained its excellent adsorption efficiency after six adsorption-desorption cycles (91.2% for MO and 93.4% for MB). The process of MO adsorption by NH2-MIL@L4 followed the Temkin model and pseudo-second-order kinetics, while MB adsorption followed the Dubinin-Radushkevich model and pseudo-second-order kinetics. Electrostatic interactions, π-π interactions, hydrogen bonding, and synergistic interactions affected the MO adsorption process of NH2-MIL@L4.

Modulating cell stiffness for improved vascularization: leveraging the MIL-53(fe) for improved interaction of titanium implant and endothelial cell.

Vascularization plays a significant role in promoting the expedited process of bone regeneration while also enhancing the stability and viability of artificial bone implants. Although titanium alloy scaffolds were designed to mimic the porous structure of human bone tissues to facilitate vascularization in bone repair, their biological inertness restricted their broader utilization. The unique attribute of Metal-organic framework (MOF) MIL-53(Fe), known as "breathing", can facilitate the efficient adsorption of extracellular matrix proteins and thus provide the possibility for efficient interaction between scaffolds and cell adhesion molecules, which helps improve the bioactivity of the titanium alloy scaffolds. In this study, MIL-53(Fe) was synthesized in situ on the scaffold after hydrothermal treatment. The MIL-53(Fe) endowed the scaffold with superior protein absorption ability and preferable biocompatibility. The scaffolds have been shown to possess favorable osteogenesis and angiogenesis inducibility. It was indicated that MIL-53(Fe) modulated the mechanotransduction process of endothelial cells and induced increased cell stiffness by promoting the adsorption of adhesion-mediating extracellular matrix proteins to the scaffold, such as laminin, fibronectin, and perlecan et al., which contributed to the activation of the endothelial tip cell phenotype at sprouting angiogenesis. Therefore, this study effectively leveraged the intrinsic "breathing" properties of MIL-53 (Fe) to enhance the interaction between titanium alloy scaffolds and vascular endothelial cells, thereby facilitating the vascularization inducibility of the scaffold, particularly during the sprouting angiogenesis phase. This study indicates that MIL-53(Fe) coating represents a promising strategy to facilitate accelerated and sufficient vascularization and uncovers the scaffold-vessel interaction from a biomechanical perspective.

Diet and risk of low back pain: a Mendelian randomization analysis.

PURPOSE: Previous epidemiological and other studies have shown an association between diet and low back pain (LBP). This study aimed to investigate the causal relationship between diet and LBP using a Mendelian randomization (MR) approach. METHODS: The three main methods in this study were weighted median, MR-Egger, and inverse variance weighting (IVW). We utilized MR-PRESSO to eliminate abnormal SNPs. Additionally, tests for pleiotropy and heterogeneity were conducted. Utilizing IVW and MR-Egger's Cochran's Q test, heterogeneity was evaluated. MR-Egger intercepts were used in pleiotropy tests. A leave-one-out analysis was also used to evaluate the stability of the study's findings. RESULTS: The frequency of alcohol intake was associated with an increased risk of LBP. Increased processed meat intake, dried fruit intake, cereal intake, and tea intake were causally associated with a decreased risk of LBP (alcohol intake frequency: odds ratio (OR) = 1.28; 95% confidence interval (CI), 1.11-1.47; P = 0.0006; processed meat intake: OR = 0.60, 95%CI 0.39-0.92, P = 0.019; dried fruit intake: OR = 0.43, 95%CI 0.29-0.66, P = 0.00008; cereal intake: OR = 0.62, 95%CI 0.42-0.92, P = 0.018; tea intake: OR = 0.75, 95%CI 0.58-0.97, P = 0.029). Heterogeneity and pleiotropy were also not found in the sensitivity analysis. The leave-one-out analysis also showed more robust results. Other dietary intakes were not causally associated with LBP. CONCLUSIONS: This two-sample MR study found that frequency of alcohol intake was associated with an increased risk of LBP, and intake of processed meat, dried fruit, cereals, and tea was associated with a decreased risk of LBP. Moreover, no causal relationship was found with LBP in the other 13 diets.

In vitro cytocompatibility of triclosan coated Polyglactin910 sutures.

Bioabsorbable sutures can improve the medical functions of existing non-absorbable sutures, and may produce new medical effects, and are expected to become a new generation of medical degradable materials. In this study, the cytocompatibility of triclosan coated polyglactin910 sutures (CTS-PLGA910) was analyzed and different concentrations of sutures were prepared. The effects of sutures on the cytotoxicity and cell proliferation of HUVEC were studied by CCK-8 assay. The hemolysis, total antioxidant capacity (T-AOC) activity and nitric oxide (NO) content were investigated to improve the blood compatibility of sutures. The results showed that the hemolysis rate of CTS-PLGA910 was less than 5%. After treatment on HUVEC cells for 48 and 72 h, there was no significant change in NO content in CTS-PLGA910 groups compared with the control group, while T-AOC activity and antioxidant capacity were significantly increased in medium and high dose groups. In summary, the blood compatibility and cell compatibility were significantly improved, which provided a basis for the clinical application of sutures in the future.

Nanoplastics Shape Adaptive Anticancer Immunity in the Colon in Mice.

The impact of nanoplastics (NPs) on human health is still not well understood, and more research is needed to better understand the risks associated with these particles. In this study, we found that oral administration of polyethylene (PE) NPs in a mice model significantly disrupted the intestinal microenvironment, which shapes adaptive immune response and favors the established in situ colorectal tumor growth. Using single-cell RNA sequencing technology, we show that NPs triggered colon IL-1ß-producing macrophages by inducing lysosome damage, leading to colonic Treg and Th17 differentiation associated with T cell exhaustion, which creates a colon environment that favors the tumor initiation and progress. A similar effect is also observed in polystyrene NPs. Our result provides insight into the potential link between NPs ingestion and colon tumorigenesis, and the urgency of addressing plastic pollution worldwide.

Reconstruction Strategy for Upper Extremity Defects After Bone Tumor Resection Based on 3D Customized Bone Cement Mold.

BACKGROUND: Reconstructing bone defects in the upper extremities and restoring their functions poses a significant challenge. In this study, we describe a novel workflow for designing and manufacturing customized bone cement molds using 3D printing technology to reconstruct upper extremity defects after bone tumor resection. METHODS: Computer tomography data was acquired from the unaffected upper extremities to create a detachable mold, which can be customized to fit the joint precisely by shaping the bone cement accordingly. Fourteen patients who underwent reconstructive surgery following bone tumor resection in the proximal humerus (13 cases) or distal radius (1 case) between January 2014 and December 2022 were retrospectively evaluated. The medical records of this case series were reviewed for the demographic, radiological, and operative data. Metastasis, local recurrence, and complication were also reviewed. Additionally, Musculoskeletal Tumor Society Score (MSTS) and Visual Analogue Scale (VAS) were used to assess clinical outcomes. RESULTS: The mean follow-up period was 49.36 ± 15.18 months (range, 27-82 months). At the end of follow-up, there were no cases of metastasis or recurrence, and patients did not experience complications such as infection, dislocation, or implant loosening. Two cases complicated with subluxation (14.3%), and 1 case underwent revision surgery for prosthetic fracture (7.1%). The average MSTS score was 23.2 ± 1.76 (77.4%, range, 66.7%-86.7%), and the postoperative VAS score was 1.86 ± 1.03 (range, 1-4), which was significantly lower than that before surgery (average preoperative VAS score was 5.21 ± 2.00 (range, 2-8)) (P < .001). CONCLUSION: Customized 3D molds can be utilized to shape bone cement prostheses, which may serve as a potential alternative for reconstructing the proximal humerus and distal radius following en bloc resection of bone tumors. This reconstruction strategy offers apparent advantages, including precise matching of articular surfaces and comparatively reduced costs.

Drug-Loaded Mesoporous Silica Nanoparticles Enhance Antitumor Immunotherapy by Regulating MDSCs.

Myeloid-derived suppressor cells (MDSCs) are recognized as major immune suppressor cells in the tumor microenvironment that may inhibit immune checkpoint blockade (ICB) therapy. Here, we developed a Stattic-loaded mesoporous silica nanoparticle (PEG-MSN-Stattic) delivery system to tumor sites to reduce the number of MDSCs in tumors. This approach is able to significantly deplete intratumoral MSDCs and thereby increase the infiltration of T lymphocytes in tumors to enhance ICB therapy. Our approach may provide a drug delivery strategy for regulating the tumor microenvironment and enhancing cancer immunotherapy efficacy.

Comparative assessment of orthodontic clear aligner versus fixed appliance for anterior retraction: a finite element study.

BACKGROUND: The aim of this study is to conduct a comparative evaluation of different designs of clear aligners and examine the disparities between clear aligners and fixed appliances. METHODS: 3D digital models were created, consisting of a maxillary dentition without first premolars, maxilla, periodontal ligaments, attachments, micro-implant, 3D printed lingual retractor, brackets, archwire and clear aligner. The study involved the creation of five design models for clear aligner maxillary anterior internal retraction and one design model for fixed appliance maxillary anterior internal retraction, which were subsequently subjected to finite element analysis. These design models included: (1) Model C0 Control, (2) Model C1 Posterior Micro-implant, (3) Model C2 Anterior Micro-implant, (4) Model C3 Palatal Plate, (5) Model C4 Lingual Retractor, and (6) Model F0 Fixed Appliance. RESULTS: In the clear aligner models, a consistent pattern of tooth movement was observed. Notably, among all tested models, the modified clear aligner Model C3 exhibited the smallest differences in sagittal displacement of the crown-root of the central incisor, vertical displacement of the central incisor, sagittal displacement of the second premolar and second molar, as well as vertical displacement of posterior teeth. However, distinct variations in tooth movement trends were observed between the clear aligner models and the fixed appliance model. Furthermore, compared to the fixed appliance model, significant increases in tooth displacement were achieved with the use of clear aligner models. CONCLUSIONS: In the clear aligner models, the movement trend of the teeth remained consistent, but there were variations in the amount of tooth displacement. Overall, the Model C3 exhibited better torque control and provided greater protection for posterior anchorage teeth compared to the other four clear aligner models. On the other hand, the fixed appliance model provides superior anterior torque control and better protection of the posterior anchorage teeth compared to clear aligner models. The clear aligner approach and the fixed appliance approach still exhibit a disparity; nevertheless, this study offers a developmental direction and establishes a theoretical foundation for future non-invasive, aesthetically pleasing, comfortable, and efficient modalities of clear aligner treatment.

3D Extruded Graphene Thermoelectric Threads for Self-Powered Oral Health Monitoring.

Flexible sensors play a crucial role in intelligent electronic devices, while strain-sensing is the fundamental feature for these sensors of different fields. Therefore, developing high-performance flexible strain sensors is essential for building the next generation of smart electronics. Here, a self-powered ultrasensitive strain sensor based on graphene-based thermoelectric composite threads through a simple 3D extrusion method is reported. The optimized thermoelectric composite threads show a large stretchable strain of over 800%. After 1000 cycles of bending, the threads still maintain excellent thermoelectric stability. The thermoelectric effect-induced electricity can realize ultrasensitive strain and temperature detection with high resolution. As wearable devices, the thermoelectric threads can also realize self-powered physiological signals monitoring, including the opening degree of mouth, occlusal frequency, and force of the tooth during the eating process. It provides significant judgment and guidance for promoting oral healthcare and developing good eating habits.

Data-driven discovery of a universal indicator for metallic glass forming ability.

Despite the importance of glass forming ability as a major alloy characteristic, it is poorly understood and its quantification has been experimentally laborious and computationally challenging. Here, we uncover that the glass forming ability of an alloy is represented in its amorphous structure far away from equilibrium, which can be exposed by conventional X-ray diffraction. Specifically, we fabricated roughly 5,700 alloys from 12 alloy systems and characterized the full-width at half-maximum, Δq, of the first diffraction peak in the X-ray diffraction pattern. A strong correlation between high glass forming ability and a large Δq was found. This correlation indicates that a large dispersion of structural units comprising the amorphous structure is the universal indicator for high metallic glass formation. When paired with combinatorial synthesis, the correlation enhances throughput by up to 100 times compared to today's state-of-the-art combinatorial methods and will facilitate the discovery of bulk metallic glasses.

Photoaging of Typical Microplastics as Affected by Air Humidity: Mechanistic Insights into the Important Role of Water Molecules.

Recent studies showed that land is the most important sink for microplastics (MPs); however, limited information is available on the photoaging processes of land surface MPs that are exposed to the air. Herein, this study developed two in situ spectroscopic methods to systematically explore the effect of air humidity on MP photoaging using a microscope of Fourier transform infrared spectroscopy and a laser Raman microscope, which were equipped with a humidity control system. Polyethylene microplastics, polystyrene microplastics, and poly(vinyl chloride) microplastics (PVC-MPs) were used as model MPs. Our results showed that relative humidity (RH) could significantly influence the MP surface oxygen-containing moieties generated from photo-oxidation, especially for PVC-MPs. As the RH level varied from 10 to 90%, a decrease in the photogenerated carbonyl group and an increase in the hydroxyl group were observed. This could be attributed to the involvement of water molecules in the production of hydroxyl groups, which subsequently inhibited carbonyl generation. Moreover, the adsorption of coexisting contaminants (i.e., tetracycline) on photoaged MPs exhibited strong RH dependence, which could be assigned to the varied hydrogen bonding between tetracycline carbonyls and aged MP surface hydroxyls. This study reveals a ubiquitous but previously overlooked MP aging route, which may account for the changed MP surface physiochemical properties under solar irradiation.

Natural Solar Irradiation Produces Fluorescent and Biodegradable Nanoplastics.

Nanoplastics (NPs) have raised global concern owing to their potential health effects. Herein, after simulated and natural solar irradiation, polyethylene, polypropylene, polystyrene, and poly(vinyl chloride) nanoplastics (PVC NPs) were observed to exhibit enhanced fluorescence, particularly PVC NPs. Furthermore, the role of photoaged NPs as a potential fluorescence indicator was evaluated by exposing a model aquatic organism Daphnia magna to these NPs. Our results revealed that photoaged NPs exhibited strong fluorescence owing to the generation of conjugated π bonds, which can achieve π-π* electron transition with low energy consumption. Photogenerated fluorescence also enabled the photoaged NPs to act as efficient fluorescent tracers, which can help track NP migration in various organisms. The results of two-photon laser confocal scanning microscopy revealed that the photoaged NPs could translocate across biological barriers and accumulate in extraintestinal tissues in addition to being ingested and excreted. Moreover, compared with pristine NPs, the photoaged NPs underwent biodegradation more easily, probably because of increased hydrophilicity due to photogenerated oxygen-containing moieties. Therefore, in addition to producing fluorescent NPs without the attachment of external fluorescent dyes, the natural photoaging process can promote the migration and degradation of photoaged NPs in food chains.

Application of three-dimensional printing individualized titanium mesh in alveolar bone defects with different Terheyden classifications: A retrospective case series study.

OBJECTIVE: To present the results of guided bone regeneration (GBR) with three-dimensional printing individualized titanium mesh (3D-PITM) applied to alveolar bone defects with different Terheyden classifications and the factors affecting the osteogenic outcome. MATERIALS AND METHODS: Fifty-nine patients, presenting with 61 defect sites, were enrolled between 2018 and 2021. GBR+3D-PITM was obtained with simultaneous or second stage implant placement. The complication rate, the success rate of the bone grafting procedure and the survival rate of the implant were documented. Bone gain, thickness of pseudo-periosteum and peri-implant marginal bone loss (MBL) were measured through digital methods by imaging data (CBCT and X-ray). RESULTS: Out of 61 sites, 20 were exposed (exposure rate: 32.8%). The width, height, and volume bone gain at P3 (mesh removal) were 5.22 ± 3.19 mm, 5.01 ± 2.83 mm, and 588.91 ± 361.23 mm3 , respectively. From P2 (3D-PITM+GBR) to P3 , changes in bone gain were not statistically different in the different Terheyden classifications, the occurrence of exposure (p < .001 for all dimensions) and the different type of pseudo-periosteum (p = .030 for width and p = .002 for height) were significantly correlated with the reduction of bone gain. Terheyden classification of the defect sites was significantly associated with the occurrence of exposure (p = .014) and types of the pseudo-periosteum (p = .015). CONCLUSION: The 3D-PITM can be used in alveolar bone defects with different Terheyden classification, but cases with severe vertical bone defects have a greater chance of the 3D-PITM exposure and the exposure can affect the outcome of bone augmentation.

Pleiotrophin attenuates the senescence of dental pulp stem cells.

OBJECTIVES: Pleiotrophin (PTN), a secreted extracellular matrix-associated protein, plays an important role in regulating the osteo/dentinogenic differentiation potential of dental pulp stem cells (DPSCs). Our previous study has demonstrated that PTN expression in young DPSCs was is 10-fold higher than that in aged DPSCs. However, the role of PTN on the in maintaining the stemness of senescent DPSCs remains unclear. The present study aimed to investigate the effect of PTN on senescent DPSCs in vitro. MATERIALS AND METHODS: Dental pulp stem cells were isolated from human third molars. PTN was knocked down using short hairpin RNAs to study the role of PTN on the senescence of DPSCs. DPSCs with aging performance were obtained by a replicative senescence cell model was obtained by the long-term culture of DPSCs to the 15th passage in vitro (P15). We then investigated the effect of PTN on senescent DPSCs (P15 DPSCs). Real-time RT-PCR, western blotting, alizarin red staining, quantitative calcium analysis, SA-ß-Gal staining, CFSE, and cell-counting kit-8 (CCK8) assays were used to study cellular senescence and function. RESULTS: The depletion of PTN increased the ratio of SA-ß-gal-positive cells, upregulated the expression of p16, and down-regulated the expression of TERT and p-p38. Furthermore, 50 pg/ml of PTN recombinant protein rescued these changes the altered ratio of SA-ß-gal-positive cells, decreased the expression of p16, enhanced TERT and p-p38 expression, as well as telomere activity, caused by PTN depletion and long-term culture. The15th passage cells displayed typical aging characteristic, including high ratio of SA-ß-gal-positive cells, increased aging-related gene expression, decreased proliferation rate, high level of Cyclin D expression, and impaired osteo/dentinogenic differentiation potential. However, 50 pg/ml of PTN recombinant protein could partially reverse these alteration rescue these changes. CONCLUSIONS: The present study demonstrated that PTN could protect DPSCs from senescence by improving the proliferation and osteo/dentinogenic differentiation ability, probably through the p38 MAPK pathway.

The effects of lingual buttons, precision cuts, and patient-specific attachments during maxillary molar distalization with clear aligners: Comparison of finite element analysis.

INTRODUCTION: This study aimed to analyze the biomechanical effects of the combined use of clear aligners (CA) and auxiliaries (precision cuts, lingual buttons, and patient-specific attachments) on mesial tipping and extrusion of the premolars during maxillary molars distalization. METHODS: Three-dimensional finite element method was employed to simulate clinical scenarios of CA with different auxiliaries for molar distalization. As such, 200 g of distal force was applied to the microimplants from the notches, lingual buttons, and hooks. Orthodontic tooth movement and the hydrostatic pressure in the periodontal ligament were compared. RESULTS: Adding auxiliaries can provide the maxillary arch anchorage and promote the distal tipping of premolars and retroclination of maxillary incisors. In contrast, this effect was more pronounced in patient-specific attachment applications than in other types of auxiliaries. The independent application of the CA caused mesial tipping and extrusion of the premolar and also caused the incisor proclination. CONCLUSIONS: The anchorage loss caused by the CA alone could be alleviated with the assistance of auxiliaries. Notably, patient-specific attachments further reinforce the anchorage of the anterior arch by incorporating anchor teeth as 1 anchorage unit.

Effects of different designs of orthodontic clear aligners on the maxillary central incisors in the tooth extraction cases: a biomechanical study.

BACKGROUND: Controlling the 3D movement of central incisors during tooth extraction cases with clear aligners is important but challenging in invisible orthodontic treatment. This study aimed to explore the biomechanical effects of central incisors in tooth extraction cases with clear aligners under different power ridge design schemes and propose appropriate advice for orthodontic clinic. METHODS: A series of Finite Element models was constructed to simulate anterior teeth retraction or no retraction with different power ridge designs. These models all consisted of maxillary dentition with extracted first premolars, alveolar bone, periodontal ligaments and clear aligner. And the biomechanical effects were analysed and compared in each model. RESULTS: For the model of anterior teeth retraction without power ridge and for the model of anterior teeth no retraction with a single power ridge, the central incisors exhibited crown lingual inclination and relative extrusion. For the model of anterior teeth no retraction with double power ridges, the central incisors tended to have crown labial inclination and relative intrusion. For the model of anterior tooth retraction with double power ridges, the central incisors exhibited a similar trend to the first kind of model, but as the depth of the power ridge increased, there was a gradual decrease in crown retraction value and an increase in crown extrusion value. The simulated results showed that von-Mises stress concentration was observed in the cervical and apical regions of the periodontal ligaments of the central incisors. The clear aligner connection areas of adjacent teeth and power ridge areas also exhibited von-Mises stress concentration and the addition of power ridge caused the clear aligner to spread out on the labial and lingual sides. CONCLUSIONS: The central incisors are prone to losing torque and extruding in tooth extraction cases. Double power ridges have a certain root torque effect when there are no auxiliary designs, but they still cannot rescue tooth inclination during tooth retraction period. For tooth translation, it may be a better clinical procedure to change the one-step aligner design to two-step process: tilting retraction and root control.