Cantilever-aided bodily protraction of a mandibular molar with clear aligner: A finite element analysis.

OBJECTIVE: To analyse the biomechanics of molar protraction through clear aligner therapy (CAT) with and without a buccal cantilever. METHODS: Models were composed of mandible, lower dentition, periodontal ligaments, attachments, a buccal cantilever, and clear aligner. Four groups were designed: (1) control (aligner only), (2) aligner+buccal cantilever with buccal class II traction, (3) aligner+buccal cantilever with buccal class II and lingual class II tractions, (4) aligner+buccal cantilever with buccal horizontal traction named buccal class I, buccal class II, and lingual class II tractions. RESULTS: CAT alone caused mesial tipping, lingual tipping, and intrusion of mandibular second molar. Adding the buccal cantilever on the mandibular second molar with 100-g buccal class II traction was effective in preventing the mesial tipping of mandibular second molar, but resulted in a greater lingual tipping tendency. Further addition of lingual class II traction prevented aforementioned lingual tipping and bodily protraction was achieved in sagittal dimension, while buccal tipping was present. Bodily protraction without buccolingual tipping was achieved through clear aligner, buccal class II, lingual class II, and buccal class I tractions, and the stress concentrated on the alveolar bone was reduced. CONCLUSION: CAT produced mesial tipping, lingual tipping, and intrusion of mandibular molar during protraction. The incorporation of the buccal cantilever into the clear aligner improves the biomechanical effect of molar protraction. Bodily molar protraction can be achieved with a judicious combination of buccal class II, lingual class II and buccal class I tractions with clear aligner and buccal cantilever.

Orthodontic traction of a deeply impacted mandibular first molar via a ramus miniscrew through lateral-window technique: A case report.

BACKGROUND: The incidence of mandibular first molar impaction is less than 0.01%, and there are no standard treatment guidelines. Orthodontic traction can be chosen as a treatment plan in some circumstances. One miniscrew in the mandibular ramus can offer sufficient anchorage for the traction of impacted mandibular molars. CASE DESCRIPTION: A 10-year-old boy had a completely labially positioned maxillary left canine and a deeply impacted mandibular left first molar associated with a dentigerous cyst. Using 2 palatal miniscrews for distalization, space was created to align the maxillary left canine. In addition, a miniscrew in the mandibular ramus facilitated the traction of the mandibular left first molar. After 3 years and 6 months of orthodontic treatment, the integrity of the dental arch was restored, and occlusal function was reestablished. PRACTICAL IMPLICATIONS: A ramus miniscrew is an effective and viable treatment option for the orthodontic traction of deeply impacted mandibular molars.

Clear aligner treatment of an adult open bite with bilateral missing mandibular first molars through molar protraction with Albert cantilever arms.

Premature loss of first permanent molars is a common occurrence in clinical practice, leading to abnormal occlusion and inefficient mastication for patients. This case report presented the orthodontic retreatment of a 32-year-old female patient who suffered from premature loss of mandibular bilateral first molars. The mesial tipping of the mandibular second molars led to an occlusal interference, resulting in a clockwise rotation of the lower jaw and an anterior open bite (AOB). We achieved long-distance molar mesialization using clear aligners with Albert cantilever arms. After 42 months of treatment, the patient's occlusion and facial profile significantly improved. The cantilever combined with the cleat aligner treatment has been clinically effective for the protraction of mandibular posterior teeth, extending the field of application of clear aligners.

Robust and Density Tunable Kevlar/Hexagonal Boron Nitride Microribbon Aerogels with Excellent Thermal, Mechanical, and Oil-Absorption Properties.

With rapid advancements in aerospace and supersonic aircraft technology, there is a growing demand for multifunctional thermal protective materials. Aerogels, known for their low density and high porosity, have garnered significant attention in this regard. However, developing a lightweight multifunctional aerogel that combines exceptional thermal and mechanical properties through a straightforward and time-efficient method remains a significant challenge. Herein, a facile and universal approach is developed for the preparation of Kevlar/hexagonal boron nitride (h-BN) aerogels, in which a spin-assisted method is applied to create robust microribbons and further accelerate solvent displacement. The resulting microribbon scaffold, with its entangled nanofiber-nanosheet morphologies, exhibits sufficient strength to prevent volume shrinkage during drying, thereby allowing precise control over aerogel density. The porous hybrid aerogels, featuring controllable geometric characteristics and tailored densities ranging from 6.9 to 100 mg cm-3, can be successfully fabricated. These aerogels exhibit excellent thermal insulation properties, and the thermal conductivities of the as-prepared KBX aerogels have a wide distribution in the range of 0.0269-0.0450 W m-1 k-1. The thermal stability of the hybrid aerogels is enhanced to 566 °C. Moreover, the resulting hybrid aerogels exhibit an ultrahigh bearing ratio, supporting more than 2000 times their own weight while maintaining stable structural integrity. These aerogels also demonstrate high compressive strength, hydrophobicity, and excellent sorption performance for various oils and solvents. Additionally, the oil-saturated aerogels can be easily recovered through heat treatment or combustion in air. The features endow hybrid Kevlar/h-BN aerogels with significant potential for applications in thermal management, environmental protection, and neutron protection.

A Bibliometric Analysis of Clear Aligner Treatment (CAT) From 2003 to 2023.

Clear aligner treatment (CAT) has been evolving over the past two decades. This study aims to conduct a comprehensive and up-to-date bibliometric analysis of publications related to CAT, presenting the research trends, landscapes, and hot spots in this field. All publications were retrieved from the Web of Science Core Collection from 2003 to 2023. In addition to a general analysis of research landscapes, the following items were analyzed, i.e., countries, institutions, authors, journals, publications, and keywords. A total of 1031 relevant publications were included in this study. From 2003 to the present, the number of publications and citations in this field showed an increasing trend. Italy led in terms of publication counts, and Sichuan University in China had the highest publication counts among institutions. In total, 33 scholars had published a minimum of 10 articles, and the collaborations among them were mostly within each country. The American Journal of Orthodontics and Dentofacial Orthopedics published the most relevant publications. "Predictability of tooth movements," "influencing factors for clinical efficacy," "biomechanics," and "patients' perception and periodontal health" stood out as the core research focus on CAT. Our study identified the most influential countries, institutions and authors, and their cooperative relationships, and detected hot research topics on CAT, calling for more high-quality international collaborative research in the future.

Accuracy of Complete-Arch Scans Obtained by Intraoral Scanner and Smartphone Three-Dimensional Scanning Applications With Different Smartphone Position Setups: An In Vitro Study.

INTRODUCTION: The high cost of intraoral scanners (IOS) for complete-arch scans makes them less accessible for many dental practitioners. As a viable alternative, smartphone scanner applications (SMP) provide comparable scanning capabilities at a significantly low cost. However, there is limited data on the accuracy of SMP, especially when used in various smartphone positions. This study aimed to compare the three-dimensional (3D) and linear accuracy of complete-arch scans acquired by an IOS and SMP (KIRI Engine, KIRI Innovations, Guangdong, China) at three shooting angles (0°, 45°, and 90° for SMP_3A) and two shooting angles (30° and 60° for SMP_2A). METHODS: A stone dental cast was scanned with a laboratory scanner as a reference, with 11 scans performed by an IOS, SMP_2A, and SMP_3A. In 3D analysis, trueness and precision were evaluated through superimposition with the reference scan and within each group, respectively, using the best-fit algorithm of Geomagic Wrap software (3D Systems, Inc., Rock Hill, SC). Trueness in linear discrepancy was assessed by comparing the occlusal-cervical and mesiodistal dimensions of reference teeth (canine, premolar, and molar), intercanine width, and intermolar width on the digital casts to measurements of the stone cast, while precision was measured using the coefficient of variance. Differences between groups were analyzed using the Friedman test, followed by the Dunn-Bonferroni post hoc test with a significance level set at 0.05. RESULTS: IOS exhibited significantly lower trueness than SMP_2A (p = 0.003) with significantly greater width discrepancies on canines (p = 0.001) and molars (p < 0.001). Discrepancy patterns differed among the three scanning methods. The IOS showed greater discrepancies on the occlusal surfaces of posterior teeth. While SMP_3A demonstrated higher variation on the palatal surfaces and interproximal areas of posterior teeth. For precision, SMP_3A (p = 0.028) and SMP_2A (p = 0.003) showed a significantly lower precision in 3D analysis, but a comparable reproducibility in linear measurement to IOS. CONCLUSION: TRIOS IOS (3Shape, Copenhagen, Denmark) exhibited lower trueness in 3D and linear accuracy analyses for complete-arch scans. The positions of the smartphone significantly enhanced trueness at the undercut region. SMP_2A and SMP_3A can be a potential alternative for precise linear measurement in complete-arch scans with selective use.

Uprighting and protraction of two unilateral mandibular molars using a cantilever arm through a sophisticated biomechanical system with clear aligner: A case report.

Although clear aligner can be efficient and predictable in some tooth movements, mandibular molar protraction is the least predictable owing to biological and biomechanical limitations. This case report presents a 20-year-old female with poor prognosed left mandibular first molar (#36), deviated dental midline and mild crowding. After extraction of #36, clear aligners and an Albert cantilever were used for treatment. Through carefully designed dual mechanical system, we achieved uprighting and protraction of #37 within 27 months, with crown and root movements of 9.9mm and 12.1mm, respectively. The predictability of the crown and root movement was 107.6% and 84.6%. Coincident dental and facial midline, class I molar and canine relationship and good root parallelism were also achieved. Large-distance mandibular molar protraction can be achieved effectively with a combination of Albert cantilever arm and clear aligner.

Exploration of bone metabolism status in the distal femur of mice at different growth stages.

The mouse femur, particularly the distal femur, is commonly utilized in orthopedic research. Despite its significance, little is known about the key events involved in the postnatal development of the distal femur. Therefore, investigating the development process of the mouse distal femur is of great importance. In this study, distal femurs of CD-1 mice aged 1, 2, 4, 6, and 8 weeks were examined. We found that the width and height of the distal femur continued to increase till the 4th week, followed with stabilization. Notably, the width to height ratio remained relatively consistent with age. Micro computed tomography analysis demonstrated gradual increases in bone volume/tissue volume, trabecular number, and trabecular thickness from 1 to 6 weeks, alongside a gradual decrease in trabecular separation. Histological analysis further indicated the appearance of the secondary ossification center at approximately 2 weeks, with ossification mostly completed by 4 weeks, leading to the formation of a prototype epiphyseal plate. Subsequently, the epiphyseal plate gradually narrowed at 6 and 8 weeks. Moreover, the thickness and maturity of the bone cortex surrounding the epiphyseal plate increased over time, reaching peak cortical bone density at 8 weeks. In conclusion, to enhance model stability and operational ease, we recommend constructing conventional mouse models of the distal femur between 4 and 8 weeks old.

Development of a novel three-dimensional injection guide for trigeminal ganglia.

BACKGROUND: Trigeminal ganglion (TG) plays an important role in the process of orthodontic pain. It's necessary to design an accurate, precise and minimally invasive trigeminal ganglion injection guide plate to study TG. METHODS: Micro-CT was used to obtain the Dicom format data, and three-dimensional (3D) software (mimics and magics23.03) was used to reconstruct 3D head models. Design and modifications of the TG injection guide plate were performed in Magic 23.03 software, and the guide plate was produced by a 3D stereolithography printer. X-ray, micro-CT, Evans blue, and virus transduction were used to demonstrate the accuracy of the guide-assisted injection. Pain levels were evaluated after using the injection guide by a bite force test and Von Frey test. RESULTS: X-ray and micro-CT tests confirmed that the injection needle reached the bilateral trigeminal ganglia fossa. The Evans blue test and virus transduction proved that the injected drug could be accurately injected into the bilateral trigeminal ganglion and the lentivirus could be successfully transfected. The percentage of accurate injection was 10/10 (bilateral trigeminal ganglia). Orofacial pain induced by the trigeminal ganglion injection was mild and returned to baseline within seven days. CONCLUSION: The injection guide described in this study is viable and reliable for the delivery of drugs and virus transduction into the trigeminal ganglia.

Seasonal human coronavirus NL63 epidemics in children in Guilin, China, reveal the emergence of a new subgenotype of HCoV-NL63.

Introduction: Seasonal human coronavirus NL63 (HCoV-NL63) is a frequently encountered virus linked to mild upper respiratory infections. However, its potential to cause more severe or widespread disease remains an area of concern. This study aimed to investigate a rare localized epidemic of HCoV-NL63-induced respiratory infections among pediatric patients in Guilin, China, and to understand the viral subtype distribution and genetic characteristics. Methods: In this study, 83 pediatric patients hospitalized with acute respiratory infections and positive for HCoV-NL63 were enrolled. Molecular analysis was conducted to identify the viral subgenotypes and to assess genetic variations in the receptor-binding domain of the spiking protein. Results: Among the 83 HCoV-NL63-positive children, three subgenotypes were identified: C4, C3, and B. Notably, 21 cases exhibited a previously unreported subtype, C4. Analysis of the C4 subtype revealed a unique amino acid mutation (I507L) in the receptor-binding domain of the spiking protein, which was also observed in the previously reported C3 genotype. This mutation may suggest potential increases in viral transmissibility and pathogenicity. Discussion: The findings of this study highlight the rapid mutation dynamics of HCoV-NL63 and its potential for increased virulence and epidemic transmission. The presence of a unique mutation in the C4 subtype, shared with the C3 genotype, raises concerns about the virus's evolving nature and its potential public health implications. This research contributes valuable insights into the understanding of HCoV-NL63's epidemiology and pathogenesis, which is crucial for effective disease prevention and control strategies. Future studies are needed to further investigate the biological significance of the observed mutation and its potential impact on the virus's transmissibility and pathogenicity.