BACKGROUND:Although the use of clear aligners (CAs) has gained popularity in orthodontics, it faces challenges in extraction cases, particularly the "roller coaster effect" (mesial molar movement, distal canine tipping, and lingual incisor tipping/extrusion). Previous finite element studies focused on CAs as force-applying agents, neglecting counterforces from teeth to CAs. This study aimed to analyze how canine distal movement patterns affect incisors via tooth-aligner force interactions. METHODS:A three-dimensional finite element model was developed, including teeth, periodontal ligament, attachments, and CAs, based on cone-beam computed tomography and intraoral scanning data. Three groups simulated different canine distal movement modes: Group 1 (bodily movement with vertical rectangular attachments), Group 2 (bodily movement with paired optimized attachments), and Group 3 (distal tipping with vertical rectangular attachments). Multi-step iterative modeling methods were used to simulate long-term treatment, analyzing tooth displacements, contact stresses, and CA deformations. RESULTS:All groups demonstrated distal tipping of canines with the rotation center at the apical third, despite bodily movements in Groups 1 and 2. Group 2 exhibited significant canine rotation (3.36°). Incisors revealed unintended displacements: Groups 1 and 2 demonstrated higher lingual cervical pressure from CAs, causing greater buccal displacement (0.30-0.39 mm) and rotation (1.30-1.74°) compared to Group 3 (0.14-0.23 mm, 0.59-1.01°). Group 3 revealed better CA adaptation and reduced incisor movement due to minimized counterforces from actively tipped canines. CONCLUSIONS:As current attachments cannot achieve bodily canine distalization, tipping is inevitable. Designed bodily movements induce CA deformation and incisor lingual tipping/extrusion, while active distal tipping reduces adverse effects. Orthodontists should avoid programming unattainable bodily canine movements in premolar extraction cases and prioritize tipping-based strategies with subsequent root control.

3D dental segmentation is a key task in digital dentistry. In real intraoral scans data (IOS), occlusion, scanning noise, and reconstruction artifacts often break down the geometric separation structure between teeth, resulting in adjacent teeth being incorrectly merged or a single tooth being over-segmented. Since existing point cloud or mesh-based methods usually rely on local neighborhood consistency, when there are spurious geometric connections, features will diffuse across instances along geometric shortcuts, resulting in instance-level error propagation. To address this issue, we propose VGDM (Visual-Guided Diffusion Modulation), which serves as a bridge between extrinsic visual localization cues and intrinsic surface features under detection settings, enabling the extrinsic cues to regulate the propagation of intrinsic surface features. Instead of global propagation on the entire intraoral scan mesh, VGDM uses the single-view 2D detection results to roughly localize the tooth region and construct local 3D surface patches based on it. Within the patch, we soft-constrain feature propagation by visual cues to suppress the cross-instance propagation generated along spurious geometric connections, and introduce a dual-stream diffusion structure to improve the overall robustness. Experimental results on the largest public intraoral dataset(Teeth3DS) show that VGDM can significantly improve the segmentation rate of tooth instances and effectively reduce the merging and over-segmentation of adjacent teeth.

Clear aligner treatment is a novel technique in current orthodontic practice. Distinct from traditional fixed orthodontic appliances, clear aligners have different material features and biomechanical characteristics and treatment efficiencies, presenting new clinical challenges. Therefore, a comprehensive and systematic description of the key clinical aspects of clear aligner treatment is essential to enhance treatment efficacy and facilitate the advancement and wide adoption of this new technique. This expert consensus discusses case selection and grading of treatment difficulty, principle of clear aligner therapy, clinical procedures and potential complications, which are crucial to the clinical success of clear aligner treatment.

Aim or purpose: To assess the necessity of TAD-assisted vertical control in camouflage treatment for skeletal Class II hyperdivergent patients and to identify factors that suggest its use. Materials and methods: This retrospective study analyzed adult skeletal Class II hyperdivergent patients treated at Peking University School and Hospital of Stomatology (2015–2020). Two groups were compared: maximum anchorage (MMA) alone and MMA with TAD-assisted vertical control (MMA+VC). Cephalometric and model superimpositions measured skeletal, dental, and soft-tissue changes, Key parameters included upper molar intrusion, mandibular plane angle, and Z angle. Multivariable regression explored the association between skeletal and dental modifications and soft tissue improvements. Results: Both groups achieved significant sagittal correction, incisor retraction, and lip retraction (P<0.05). The MMA+VC group uniquely demonstrated significant maxillary molar intrusion (−2.25±1.03 mm) and mandibular counterclockwise rotation (−1.82±1.38°, P<0.05), which correlated with superior soft-tissue outcomes: Z-angle improvement (15.25 ± 5.30°, P < 0.05) and reduced chin thickness (−0.97±0.45 mm, P<0.05). Multivariate regression demonstrated that decreased mandibular plane angle and upper incisor inclination, coupled with improved chin projection, collectively drove Z-angle enhancement. Conclusions: TAD-assisted vertical control can achieve intrusion of approximately 2 mm for the upper first molars and induce mandibular counterclockwise rotation of approximately 1.8°. Moreover, it is especially important for patients without sufficient retraction of the upper incisors or a satisfactory chin shape.

OBJECTIVE:To investigate the changes and symmetry of facial soft tissue during posed smile, to analyze the feature of posed smile in different gender, and verify the reproducibility of posed smile. METHODS:Three-dimensional (3D) facial images of 41 adults (16 males and 25 females with an average age of 26.76±2.70 years) which were taken by FaceScan three-dimensional sensor, including one rest position and two posed smile images. Then these images were imported into 3D soft tissue analysis software for model repositioning. 3D morphable model method (3DMM) was carried out to automatic landmarks setting. After that, the measurement of the eyes, cheeks, nose and perioral area were carried out for 3D soft tissue analysis. Finally, the changes and symmetry of the soft tissues between the two expression states and the gender differences during the posed smiles were compared. Meanwhile, the reproducibility of posed smile was statistically tested. RESULTS:Compared with the rest position, except for nasolabial angle (1.45°±7.65°), the measurements of 3D soft tissue in other region were changed in posed smile (P < 0.001). It should be noted that the eye region was also significantly changed (P < 0.001). Furthermore, the prominent feature of posed smile was that the alar base length became longer, the upper and lower vermilions were narrow and thin, and the mentolabial furrows became shallow. Meanwhile the chin extended anteriorly while the mouth retracted; During posed smile, the labial fissure asymmetry [2.78 (1.73, 3.49) mm], mid-infraorbital asymmetry [2.36 (1.22, 3.27) mm] and outercanthal asymmetry [2.31(1.29, 2.80) mm] were most apparent. Compared with the rest position, the asymmetry was not significantly increased except for cheilion and alar curvature points during the posed smile (P>0.05). In the posed smile, the changes of the right palpebral fissure height and the thickness of lower vermilion (|Li-Stoi| z) of males were greater than those of females (P < 0.05), and asymmetry of exocanthion and cheekbone increased more than that of females (P < 0.05). There was no obvious difference between the two posed smiles. CONCLUSION:In this study, during the posed smile the soft tissues of the eyes, cheeks, nose, lips and chin changed in different degrees, and the asymmetry of cheilion and alar curvature point was greater than that of the rest position; In addition, the reproducibility of posed smile was excellent, which can be a reference for clinical aesthetics and functional research of smile.

Chronic bacterial infections are a key pathological factor hindering wound healing, significantly increasing the incidence of wound sepsis. Existing therapeutic strategies exhibit certain limitations, leading to a continuous decline in clinical efficacy. Therefore, there is an urgent need for the development of novel antibacterial materials to mitigate the risks associated with bacterial infections. In this study, a new antibacterial strategy is proposed, utilizing the flexoelectric polarization of manganese dioxide (MnO2) nanoflowers (NFs) to generate reactive oxygen species (ROS) at the site of infected wounds, achieving in situ and broad-spectrum bacterial eradication. Upon external ultrasound (US) stimulation, the flexoelectric polarization induced in the MnO2 NFs results in the generation of abundant ROS on the material surface, which disrupts the integrity of bacterial cell membranes, leading to their inactivation. Compared to conventional photodynamic therapy, this strategy achieves higher ROS generation efficiency (65.3% methylene blue (MB) degradation in 25 min) without light dependency. In vitro experiments confirmed the antibacterial efficacy, with the inactivation rates for Escherichia coli and Staphylococcus aureus reaching 66.22% and 70.67%, respectively. Furthermore, excellent antibacterial effects were observed at the site of infected wounds, promoting wound healing. The integration of the flexoelectric effect into material-based antibacterial strategies holds promise for expanding the range of novel antibacterial materials in the future.

SARS-CoV-2 infection-induced hyper-inflammation links to the acute lung injury and COVID-19 severity. Identifying the primary mediators that initiate the uncontrolled hypercytokinemia is essential for treatments. Mast cells (MCs) are strategically located at the mucosa and beneficially or detrimentally regulate immune inflammations. In this study, we showed that SARS-CoV-2-triggered MC degranulation initiated alveolar epithelial inflammation and lung injury. SARS-CoV-2 challenge induced MC degranulation in ACE-2 humanized mice and rhesus macaques, and a rapid MC degranulation could be recapitulated with Spike-RBD binding to ACE2 in cells; MC degranulation altered various signaling pathways in alveolar epithelial cells, particularly, the induction of pro-inflammatory factors and consequential disruption of tight junctions. Importantly, the administration of clinical MC stabilizers for blocking degranulation dampened SARS-CoV-2-induced production of pro-inflammatory factors and prevented lung injury. These findings uncover a novel mechanism for SARS-CoV-2 initiating lung inflammation, and suggest an off-label use of MC stabilizer as immunomodulators for COVID-19 treatments.

Tooth arrangement is an essential step in the digital orthodontic planning process. Existing learning-based methods use hidden teeth features to directly regress teeth motions, which couples target pose perception and motion regression. It could lead to poor perceptions of three-dimensional transformation. They also ignore the possible overlaps or gaps between teeth of predicted dentition, which is generally unacceptable. Therefore, we propose DTAN, a differentiable collision-supervised tooth arrangement network, decoupling predicting tasks and feature modeling. DTAN decouples the tooth arrangement task by first predicting the hidden features of the final teeth poses and then using them to assist in regressing the motions between the beginning and target teeth. To learn the hidden features better, DTAN also decouples the teeth-hidden features into geometric and positional features, which are further supervised by feature consistency constraints. Furthermore, we propose a novel differentiable collision loss function for point cloud data to constrain the related gestures between teeth, which can be easily extended to other 3D point cloud tasks. We propose an arch-width guided tooth arrangement network, named C-DTAN, to make the results controllable. We construct three different tooth arrangement datasets and achieve drastically improved performance on accuracy and speed compared with existing methods.

Temporomandibular joint (TMJ) disc displacement is one of the most significant subtypes of temporomandibular joint disorders, but its etiology and mechanism are poorly understood. In this study, we elucidated the mechanisms by which destruction of inflamed collagen fibrils induces alterations in the mechanical properties and positioning of the TMJ disc. By constructing a rat model of TMJ arthritis, we observed anteriorly dislocated TMJ discs with aggravated deformity in vivo from five weeks to six months after a local injection of Freund’s complete adjuvant. By mimicking inflammatory conditions with interleukin-1 beta in vitro, we observed enhanced expression of collagen-synthesis markers in primary TMJ disc cells cultured in a conventional two-dimensional environment. In contrast, three-dimensional (3D)-cultivated disc cell sheets demonstrated the disordered assembly of inflamed collagen fibrils, inappropriate arrangement, and decreased Young’s modulus. Mechanistically, inflammation-related activation of the nuclear factor kappa-B (NF-κB) pathway occurs during the progression of TMJ arthritis. NF-κB inhibition reduced the collagen fibril destruction in the inflamed disc cell sheets in vitro, and early NF-κB blockade alleviated collagen degeneration and dislocation of the TMJ discs in vivo. Therefore, the NF-κB pathway participates in the collagen remodeling in inflamed TMJ discs, offering a potential therapeutic target for disc displacement.

Abstract Background In this study, we sought to quantify the influence of vertical control assisted by a temporary anchorage device (TAD) on orthodontic treatment efficacy for skeletal class II patients with a hyperdivergent facial type and probe into the critical factors of profile improvement. Methods A total of 36 adult patients with skeletal class II and a hyperdivergent facial type were included in this retrospective case–control study. To exclude the effect of sagittal anchorage reinforcement, the patients were divided into two groups: a maxillary maximum anchorage (MMA) group (N = 17), in which TADs were only used to help with anterior tooth retraction, and the MMA with vertical control (MMA + VC) group (N = 19), for which TADs were also used to intrude the maxillary molars and incisors. The treatment outcome was evaluated using dental, skeletal, and soft-tissue-related parameters via a cephalometric analysis and cast superimposition. Results A significant decrease in ANB (P < 0.05 for both groups), the retraction and uprighting of the maxillary and mandibular incisors, and the retraction of protruded upper and lower lips were observed in both groups. Moreover, a significant intrusion of the maxillary molars was observed via the cephalometric analysis (− 1.56 ± 1.52 mm, P < 0.05) and cast superimposition (− 2.25 ± 1.03 mm, P < 0.05) of the MMA + VC group but not the MMA group, which resulted in a remarkable decrease in the mandibular plane angle (− 1.82 ± 1.38°, P < 0.05). The Z angle (15.25 ± 5.30°, P < 0.05) and Chin thickness (− 0.97 ± 0.45°, P < 0.05) also improved dramatically in the MMA + VC group, indicating a better profile and a relaxed mentalis. Multivariate regression showed that the improvement in the soft tissue was closely related to the counterclockwise rotation of the mandible plane (P < 0.05). Conclusions TAD-assisted vertical control can achieve intrusion of approximately 2 mm for the upper first molars and induce mandibular counterclockwise rotation of approximately 1.8°. Moreover, it is especially important for patients without sufficient retraction of the upper incisors or a satisfactory chin shape.

Inter-subtype recombination is the main force for the complexity of HIV-1 genetic diversity,which increases the difficulty of preventing HIV-1 infection and administering antiretroviral therapy for people living with HIV.To date,143 circulating recombinant forms(CRFs)have been re-ported globally,43 of which were identified in China.1 Moreover,HIV-1 strains that are produced by second-gen-eration combinations,including unique recombinant forms and CRFs,such as CRF105_0108,CRF123_0107,and CRF134_0185,have been commonly reported in recent years.The present study identified a novel second-gener-ation recombinant form of HIV-1 comprising CRF07_BC and subtype C and designated CRF144_07C.To our knowledge,this was the first report of HIV CRFs comprising CRF07_BC and subtype C,further indicating the complexity of HIV genetic diversity in China.

OBJECTIVE:This study aimed to investigate the biomechanical effects of clear aligner (CA) with different shape designs at extraction space (CAES) area during space closing. MATERIALS AND METHODS:A finite-element method (FEM) model of mandibular dentition, periodontal ligaments, attachments, and corresponding CA was established. The connecting rod design of CAES was modelled for the control group. Eight test groups with different heights of CAES from -4 mm to +4 mm were designed. Tooth displacement tendencies were calculated. The maximum principal stress in PDLs, teeth, and CAs was analysed. Both global coordinate system and local coordinate system were also used to evaluate individual tooth movements. RESULTS:Across all groups, stresses concentrated on the lingual outer surface of CAESs. For the lowered CAES groups, both the stress value and the stress distribution area at CAESs were increased. The lowered CAES groups showed reduced movement in anterior teeth and less tipping tendency of the canines. CONCLUSION:The shape of CAES has a biomechanical impact on anterior teeth movement and should be considered in aligner design. The results suggest that increasing the height of CAES can enhance anterior teeth retraction, while lowered CAES may facilitate controlled root movement. Changes in the shape of CAES represent a potential direction for biomechanical improvement of clear aligner in extraction cases and are worth exploring.

Abstract Background Molar distalization with clear aligners (CAs) is a common treatment. However, when the molars reach their target position and the distal movement of premolars begins, the mesial movement of molars might reduce the overall efficiency of molar distalization. This study aimed to investigate tooth movement patterns under different CA designs in the premolar distalization stage using a four-dimensional mechanical simulation method. Methods A finite element method (FEM) model encompassing the maxillary dentition, periodontal ligaments, attachments, and associated CAs was constructed. The simulation aimed to replicate a premolar distalization of 2 mm within 10 sequential steps. Buccal interradicular mini-implants were used. Three groups of CAs were designed: the conventional CA design group (Con group), the second molar half-wrap group (SMHW group) and the all-molar half-wrap group (MHW group). An iterative computational approach was employed to simulate prolonged tooth movement resulting from orthodontic forces. Additionally, morphological alterations in the CA throughout the staging process were simulated utilizing the thermal expansion method. Results Compared with the Con and SMHW groups, the MHW group presented significantly reduced mesial movement of the first and second molars. However, the MHW group presented the greatest displacement of canines and incisors. The distalization efficiency of premolars in the MHW group reached 95.5–96.5%, which was substantially greater than that in the Con group (84.5–85%) and the SMHW group (75–75.5%). Conclusions The four-dimensional mechanical simulation results indicate that during the process of premolar distalization with CA, removing the distal portion of the aligner covering the first and second molars (MHW group) can effectively reduce the mesial movement of molars. Consequently, this approach can increase the overall efficiency of molar distalization.

Bone defects caused by trauma or tumor led to high medical costs and poor life quality for patients. The exosomes, micro vesicles of 30-150 nm in diameter, derived from macrophages manipulated bone regeneration. However, the role of hydrogen sulfide (H2S) in the biogenesis and function of exosomes and its effects on bone regeneration remains elusive. In this study, we used H2S slow releasing donor GYY4137 to stimulate macrophages and found that H2S promoted the polarization of M2 macrophages to increase bone regeneration of MSCs in vitro and in vivo. Moreover, we developed the H2S pre-treated M2 macrophage exosomes and found these exosomes displayed significantly higher capacity to promote bone regeneration in calvarial bone defects by reestablishing the local immune microenvironment. Mechanically, H2S treatment altered the protein profile of exosomes derived from M2 macrophages. One of the significantly enriched exosomal proteins stimulated by H2S, moesin protein, facilitated the exosomes endocytosis into MSCs, leading to activated the I3-catenin signaling pathway to promote osteogenic differentiation of MSCs. In summary, H2S pretreated M2 exosomes promoted the bone regeneration of MSCs via facilitating exosomes uptake by MSCs and activate I3-catenin signaling pathway. This study not only provides new strategies for promoting bone regeneration, but also provides new insights for the effect and mechanism of exosomes internalization.

OBJECTIVE:To investigate the hard and soft tissue changing trend and contributing factors of skeletal class Ⅱ hyperdivergent patients before and after orthodontic camouflage treatment by analyzing the cephalogram and the three dimensional (3D) facial scan data. METHODS:Eighteen skeletal class Ⅱ hyperdivergent adult female patients who finished camouflage orthodontic treatment were selected. Skeletal and dental measurements were carried out with the cephalometric analysis before and after the treatment. 3D facial data before and after orthodontic treatment were acquired and the anatomical landmarks were set after the repositioning and superimposition process. Hard tissue measurement included 17 mea-surement indicators (sella-nasion-subspinale angle, sella-nasion-supramental angle, subspinale-nasion-supramental angle, facial angle, angle of convexity, Frankfort horizontal plane-mandibular plane angle (FH-MP), Y axis angle, sella-nasion plane-mandibular plane angle (MP-SN), pogonion-nasion-supramental distance, upper incisor-nasion-subspinale distance, upper incisor to sella-nasion, lower incisor-nasion-supramental distance, lower incisor-nasion-supramental angle, upper incisor to lower incisor, upper incisor to sella-nasion, lower incisor-mandibular plane angle, and Z angle), and the changes before and after treatment were measured for 11 of them. Twenty soft tissue landmarks (left/right cheekbone, left/right chelion, left/right crista philtra, soft tissue gnathion, left/right gonion, glabella, labrale infe-rius, labrale superius, soft tissue menton, left/right mid-mandibular border, soft tissue pogonion, stomion superius, sublabial, subnasale, and supralabial) and 9 soft tissue indicators (lower lip height, facial convexity, lower vermilion height, mandibular contour, nasolabial angle, philtral length, philtral width, upper lip height, and upper vermilion height) were measured and recorded for treatment changes. Linear-regression analysis and correlation analysis were carried out for analyzing the relationship between hard and soft tissue changes before and after the treatment. RESULTS:Significant differences were noticed for 18 out of the 20 cephalometric measurements and facial measurements before and after the treatment (P < 0.05), which mainly represented the sagittal retraction of lip area after the treatment. Significant vertical displacements were revealed for soft tissue menton after treatment [(1.88±2.61) mm, P < 0.05]. Significant sagittal displacements were revealed for left/right cheilion [(-2.95±1.9) mm, (-2.90±1.92) mm], labrale inferius[(-4.94±1.95) mm], labrale superius[(-3.25±1.44) mm], sublabial [(-3.10±3.5) mm], and subnasale [(-1.23±1.06) mm] after treatment (P < 0.05). An average of 4.10°±2.57° increasement was noticed for Z angle after treatment. High correlation (r>0.7) was noticed for the displacement of menton after treatment with FH-MP, with the rate of -0.183 :1, and MP-SN, with the rate of -0.157 :1. Moderate correlations (0.7≥r>0.4) were noticed for the other measurements with correlations (P < 0.05). CONCLUSION:A certain extent of facial improvements could be achieved with orthodontic camouflage treatment for skeletal class Ⅱ hyperdivergent patients, which were mostly represented by the improvement of sagittal relationship of nose, lips, and chin. Certain correlations were noticed for the hard and soft tissue changes.

Three-dimensional (3D) facial models have been increasingly applied in orthodontics, orthognathic surgery, and various medical fields. This study proposed an approach to reconstructing 3D facial models from standard orthodontic frontal and lateral images, providing an efficient way to expand 3D databases. A total of 23 participants (average age 20.70 ± 5.36 years) were enrolled. Based on the Hifi3D face model, 3D reconstructions were generated and compared with corresponding face scans to evaluate their accuracy. Root mean square error (RMSE) values were calculated for the entire face, nine specific facial regions, and eight anatomical landmarks. Clinical feasibility was further assessed by comparing six angular and thirteen linear measurements between the reconstructed and scanned models. The RMSE of the reconstruction model was 2.00 ± 0.38 mm (95% CI: 1.84–2.17 mm). High accuracy was achieved for the forehead, nose, upper lip, paranasal region, and right cheek (mean RMSE < 2 mm). The forehead area showed the smallest deviation, at 1.52 ± 0.88 mm (95% CI: 1.14–1.90 mm). In contrast, the lower lip, chin, and left cheek exhibited average RMSEs exceeding 2 mm. The mean deviation across landmarks was below 2 mm, with the Prn displaying the smallest error at 1.18 ± 1.10 mm (95% CI: 0.71–1.65 mm). The largest discrepancies were observed along the Z-axis (Z > Y > X). Significant differences (p < 0.05) emerged between groups in the nasolabial, nasal, and nasofrontal angles, while the other 13 linear and 3 angular measurements showed no statistical differences (p > 0.05). This study explored the feasibility of reconstructing accurate 3D models from 2D photos. Compared to facial scan models, the Hifi3D face model demonstrated a 2 mm deviation, with potential for enriching 3D databases for subjective evaluations, patient education, and communication. However, caution is advised when applying this model to clinical measurements, especially angle assessments.

Objective:This study aims to distinguish sagittal and vertical skeletal discrepancies using three machine learning methods based on three-dimensional (3D) facial profile, and a comparison among the three methods was carried out, and the discriminant features were screened.Methods:Three dimensional facial profiles were collected from 292 patients before orthodontic treatment. Cephalometric analysis was conducted for diagnosis of sagittal and vertical skeletal discrepancies. The 3D morphable model method was used to obtain soft tissue landmarks. The coordinates of landmarks, along with their geometric features and demographic characteristics, were set as features for machine learning. Random Forest (RF), AdaBoost, and Multi-Layer Perceptron (MLP) were used for skeletal discrepancies discrimination. Each model was evaluated using the receiver operating characteristic curve (ROC) and the area under the curve (AUC) was calculated. Features with the highest Gini importance were selected.Results:The AUC of MLP was the largest for sagittal pattern (0.92 for Class Ⅱ and 0.97 for Class Ⅲ). For the vertical pattern, Random Forest had the largest AUC (hypodivergence 0.84, hyperdivergence 0.88). The accuracy of discrimination of the three algorithms for sagittal pattern (Class Ⅱ: RF 90.0%, AdaBoost 85.7%, MLP 95.0%; Class Ⅲ: RF 84.6%, AdaBoost 92.3%, MLP 93.3%) was better than that of vertical pattern (hypodivergence: RF 68.2%, AdaBoost 72.0%, MLP 76.9%; hyperdivergence: RF 76.2%, AdaBoost 77.8%, MLP 69.6%). The results of feature screening showed that the most significant features for the Class Ⅱ and hyperdivergence were the angle of the interbrow point to the premental point to the subnasal septum point, and the angle of the midpoint of the bilateral temple point to the midpoint of the bilateral cheilion point to the premental point.Conclusions:Machine learning methods can assist in identifying sagittal and vertical skeletal deformities to a certain extent through three-dimensional images, and the features with the most significance for discrimination of skeletal patterns were revealed.

Objectives We used three-dimensional (3D) virtual images to undertake a subjective evaluation of how different factors affect the perception of facial asymmetry among orthodontists and laypersons with the aim of providing a quantitative reference for clinics. Materials and methods A 3D virtual symmetrical facial image was acquired using FaceGen Modeller software. The left chin, mandible, lip and cheek of the virtual face were simulated in the horizontal (interior/exterior), vertical (up/down), or sagittal (forward or backward) direction in 3, 5, and 7 mm respectively with Maya software to increase asymmetry for the further subjective evaluation. A pilot study was performed among ten volunteers and 30 subjects of each group were expected to be included based on 80% sensitivity in this study. The sample size was increased by 60% to exclude incomplete and unqualified questionnaires. Eventually, a total of 48 orthodontists and 40 laypersons evaluated these images with a 10-point visual analog scale (VAS). The images were presented in random order. Each image would stop for 30 s for observers with a two-second interval between images. Asymmetry ratings and recognition accuracy for asymmetric virtual faces were analyzed to explore how different factors affect the subjective evaluation of facial asymmetry. Multivariate linear regression and multivariate logistic regression models were used for statistical data analysis. Results Orthodontists were found to be more critical of asymmetry than laypersons. Our results showed that observers progressively decreased ratings by 1.219 on the VAS scale and increased recognition rates by 2.301-fold as the degree of asymmetry increased by 2 mm; asymmetry in the sagittal direction was the least noticeable compared with the horizontal and vertical directions; and chin asymmetry turned out to be the most sensitive part among the four parts we simulated. Mandible asymmetry was easily confused with cheek asymmetry in the horizontal direction. Conclusions The degree, types and parts of asymmetry can affect ratings for facial deformity as well as the accuracy rate of identifying the asymmetrical part. Although orthodontists have higher accuracy in diagnosing asymmetrical faces than laypersons, they fail to correctly distinguish some specific asymmetrical areas.

Osteoarthritis (OA) is a degenerative disease that causes chronic pain and joint swelling and even disables millions of patients. However, current non-surgical treatment for OA can only relieve pain without obvious cartilage and subchondral bone repair. Mesenchymal stem cell (MSC)-secreted exosomes have promising therapeutic effects on knee OA, but the efficacy of MSC-exosome therapy is not well determined, and the mechanisms involved are still unclear. In this study, we isolated dental pulp stem cell (DPSC)-derived exosomes by ultracentrifugation and determined the therapeutic effects of a single intra-articular injection of DPSC-derived exosomes in a mice knee OA model. The results showed that the DPSC-derived exosomes effectively improved abnormal subchondral bone remodeling, inhibited the occurrence of bone sclerosis and osteophytes, and alleviated cartilage degradation and synovial inflammation in vivo. Moreover, transient receptor potential vanilloid 4 (TRPV4) was activated during the progression of OA. Enhanced TRPV4 activation facilitated osteoclast differentiation, and TRPV4 inhibition blocked this process in vitro. DPSC-derived exosomes repressed osteoclast activation in vivo by inhibiting TRPV4 activation. Our findings demonstrated that a topical, single injection of DPSC-derived exosomes is a potential strategy for knee OA treatment, and that the exosomes regulated osteoclast activation by TRPV4 inhibition, which may act as a promising target for clinical OA treatment.

目的 对于正畸矫治而言,牙齿在正畸力作用下的长期移动分析较以往的正畸加力瞬时位移更有临床意义.本研究通过基于自动迭代计算的有限元分析方法探究轻力颌间牵引的作用下下牙列远中移动时的趋势.方法 本有限元研究搭建包括了下牙列、牙周膜、直丝弓矫治器的有限元模型.模拟50g的颌间轻力牵引力进行下牙列移动.通过牙周膜自动迭代计算的方法模拟牵引力长期作用下下牙齿的移动.获得每步迭代计算中牙冠、牙根标志点的三维移动量.结果 本研究迭代计算200次时展示出各牙齿移动较为明显的趋势.中切牙及侧切牙均有明显的舌倾趋势,冠顶点的舌向位移分别为1.72 mm与2.26 mm.尖牙至第二磨牙均有(0.81～0.39)mm不等的远中倾斜趋势.中切牙及侧切牙均有较明显的向伸长趋势,分别为0.49 mm、0.53 mm.第二前磨牙出现了0.19 mm的压低,其余牙均有少量伸长,纵曲线加深.结论 本研究初步完成了针对牙齿在正畸力作用下的长期移动的基于自动迭代计算的有限元分析方法的实现.定量地揭示了轻力颌间牵引作用下下牙列远中移动时的趋势.