Deciphering the Mutilation: Skillful Orthodontic Treatment Using Temporary Anchorage Devices and Asymmetric Extractions for a Patient With a Knife-Edge Ridge.

One of the biggest challenges in orthodontic management of adult patients is the presence of mutilated dentition, which is characterized by severe tooth loss and subsequent tipping of adjacent teeth or extruding of antagonists, worsening the malocclusion. As they offer a solid anchor for intricate tooth movement, temporary anchorage devices (TADs) have proven invaluable to orthodontic treatment. In this case study, we highlight the importance of TADs in getting the best possible treatment outcomes while describing the effective management of a patient with mutilated dentition. TADs made it possible to control tooth movement precisely, restoring esthetics and functional occlusion. This case report emphasizes the value of TADs in contemporary orthodontic practice and shows their potential for correcting mutilated dentition.

What is the impact of patient attributes, implant characteristics, surgical techniques, and placement location on the success of orthodontic mini-implants in young adults? A Systematic Review and Meta-Analysis.

Background: Temporary anchorage devices (TADs) address challenges in traditional orthodontic anchorage like patient compliance and precision, showing significantly improved clinical outcomes, particularly for cases requiring maximum anchorage. Materials and Methods: A systematic electronic search was performed in five research databases, focusing on studies published between 2015 and 2023. The ROBINS-I tool from the Cochrane Bias Methods Group assessed the risk of bias. Data analysis included categorical and numerical variables, with categorical variables analyzed using Cohen's method in a random effects model to account for variability. Sensitivity and heterogeneity were evaluated using a 'leave-one-out' approach and the I 2 statistic, respectively. At the same time, publication bias was checked using Egger's test, with findings presented through Forest and Funnel plots. Numerical variables were subjected to weighted regression analysis. Results: Examination of 15 studies involving 1981 patients and 3272 orthodontic mini-implants identified key factors affecting implant stability. Failure rates varied significantly, influenced by factors such as the characteristics and insertion site of the orthodontic mini-implants (OMIs), patient-specific variables, and operator experience. Notably, the insertion site and implant characteristics like size did not significantly affect failure rates, but there was a negative correlation between the magnitude of force applied and failure rates. Conclusion: The success of orthodontic mini-implants is broadly consistent across patient demographics and is not significantly impacted by gender or age, though failure rates were higher in males and when implants were placed in the maxilla. These findings suggest that higher applied forces might reduce failure rates. Clinical Significance: This review underlines mini-implant efficacy across varied patient demographics, emphasizing the importance of site selection, jaw location, and force application in enhancing success rates and guiding tailored treatment strategies.PROSPERO ID CRD42023411955.

Boehmeria Nivea Extract (BNE-RRC) Reverses Epithelial-Mesenchymal Transition and Inhibits Anchorage-Independent Growth in Tumor Cells.

The epithelial-mesenchymal transition (EMT) phenotype, identified as a significant clinical indicator in regard to cancer, manifests as a biological process wherein cells transition from having epithelial to mesenchymal characteristics. Physiologically, EMT plays a crucial role in tissue remodeling, promoting healing, repair, and responses to various types of tissue damage. This study investigated the impact of BNE-RRC on oral cancer cells (KB) and revealed its significant effects on cancer cell growth, migration, invasion, and the EMT. BNE-RRC induces the epithelial-like morphology in KB cells, effectively reversing the EMT to a mesenchymal-epithelial transition (MET). Extraordinarily, sustained culturing of cancer cells with BNE-RRC for 14 days maintains an epithelial status even after treatment withdrawal, suggesting that BNE-RRC is a potential therapeutic agent for cancer. These findings highlight the promise of BNE-RRC as a comprehensive therapeutic agent for cancer treatment that acts by inhibiting cancer cell growth, migration, and invasion while also orchestrating a reversal of the EMT process. In this study, we propose that BNE-RRC could be an effective agent for cancer treatment.

Analysis on slope stability by anchorage based on soil creep with flood effect.

In order to analyze the adverse effect of flood affection on slope stability, the analytical expressions of buoyancy force and capillary force, hydrodynamic pressure and impact force, and scour erosion were proposed based on the aging characteristics of soil shear strength and limit equilibrium theory. According to the load combination and flood action, shear failure occurs preferentially at the foot of slope. Then, the plastic zone continues to extend upward to produce traction landslide disaster mode. Furthermore, the power function relation between shear strength index and time was established. The nonlinear accelerated creep model was also obtained. At the same time, the safety factor formula for flood loading effect slope aging stability, the time-varying characteristic value of anchor force and the compensation value of anchor force were also obtained and used to research sliding mechanism. In addition, the numerical calculation example shows that the slope safety factor decreases by more than 20 % considering the effect of flood ascending scour and impact, and the compensation value of anchorage force increases obviously with time increasing. Simultaneously, the change rate of compensation value of anchorage force increases nonlinearly with the increase of design safety factor.

Study of the static response and zoning of the existing tunnel adjacent to the suspension bridge's tunnel-type anchorage.

Due to the ability to utilize the strength of the surrounding rock to enhance bearing capacity, tunnel-type anchorages have been consistently utilized in suspension bridges. Nevertheless, a close interaction occurs between the tunnel and the tunnel-type anchor when a highway tunnel is connected to a suspension bridge. This study employed numerical simulation and theoretical analysis based on the G317 Line Huangjiayuan tunnel and Zipingpu Bridge tunnel-type anchorage project, focusing on this specific type of adjacent engineering. Firstly, the discriminant degree of adjacent influence suitable for the interaction between the tunnel-type anchorage and the tunnel structure is established. The calculation conditions are distinguished by the influencing factors determined in the discriminant. The interaction law between tunnel-type anchorage and pre-built tunnel structure is further obtained. Using the method of curve regression, based on the criterion of proximity influence degree, the partition of mutual influence degree between the tunnel-type anchorage and the tunnel structure is obtained. At the same time, it is concluded that under the original design condition, the displacement degree of the tunnel structure will be greatly affected, and the tunnel structure is located in the strong influence area. According to the partition result, under the benchmark engineering geological condition, it is suggested that the angle of intersection between tunnel anchorage and tunnel structure should be increased to 3.3° and the anchor body inclination should be increased to 44°.

Influence of vitamin D in orthodontic tooth movement-a systematic review and meta-analysis of randomized controlled trials in humans.

BACKGROUND: Orchestration of tooth movement necessitates an equilibrium of bone synthesis and resorption. Vitamin D, through receptor-mediated actions, regulates the differentiation and maturation of osteoblasts and also induces osteoclastogenesis, maintaining this equilibrium. OBJECTIVE: To analyze the impact of vitamin D in orthodontic tooth movement (OTM). SEARCH METHOD: A comprehensive exploration of the existing literature was conducted by systematic search through seven e-databases. SELECTION CRITERIA: The criteria for inclusion were established using the PICO format: Orthodontic patients treated with fixed appliance (P), administered with vitamin D3 (I), collated with appropriate control groups (C), with tooth movement as the primary outcome and root resorption, anchorage loss, gingival crevicular fluid (GCF) volume, pain perception, and alveolar bone density as the secondary outcome (O). DATA COLLECTION AND ANALYSIS: After an extensive database search, 251 articles were obtained. Six articles were chosen following a stringent selection using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The critical appraisal of randomized control trials (RCTs) involved the meticulous application of the RoB 2 tool. The quantitative synthesis incorporated a subset of six articles only. RESULTS: In the meta-analysis investigating the influence of vitamin D on OTM, a notable disparity was evident between the vitamin D and control groups. Specifically, the standardized mean difference (SMD) stood at 1.43, accompanied by a 95% confidence interval (CI) ranging from 0.691 to 2.169 (P = .00154). For root resorption, the SMD was recorded at -0.51, with a 95% CI spanning from -3.051 to 2.031 (P = .11). CONCLUSIONS: The rate of tooth movement was enhanced by systemic and local administration of vitamin D. However, the inadequacy of available data is a hindrance in determining conclusively the impact of vitamin D on the extent of root resorption. The resolution of this quandary needs future human studies devoted toward investigating the influence of vitamin D in the realms of OTM and associated root resorption, thereby providing a definitive elucidation. REGISTRATION DETAILS: Prospero- CRD42023491783.

Evaluating the efficiency of mandibular molar protraction using Herbst appliances versus temporary anchorage devices: a retrospective case-controlled study.

BACKGROUND: Mandibular second premolar agenesis is a common problem in orthodontics and is often treated in conjunction with maxillary counterbalancing extractions. However, in cases without maxillary crowding or dental protrusion, space closure may pose challenges leading to compromised occlusal results or patient profile. Multiple techniques have been described to treat these patients; nevertheless, there is a paucity of data comparing effectiveness of space closure utilizing various anchorage techniques. The goal of this study is to assess the effectiveness of the Herbst device during mandibular molar protraction and compare it to the use of temporary anchorage device (TADs) in patients with mandibular second premolar agenesis. MATERIALS AND METHODS: This retrospective study included 33 patients with mandibular premolar agenesis treated without maxillary extractions. Of these patients, 21 were treated with protraction Herbst devices and 12 with TADs. Changes in molar and incisor positions, skeletal base positions and occlusal plane angulations were assessed on pretreatment (T0) and post-treatment (T1) lateral cephalograms. Scans/photographs at T0 and T1 were used to evaluate canine relationship changes representing anchorage control. Space closure and breakage/failure rates were also compared. Data was analyzed with paired and unpaired t-tests at the significance level of 0.05. RESULTS: Within the Herbst group, changes in mandibular central incisor uprighting and mandibular molar crown angulations were statistically significant. However, no significant differences were noted between the Herbst and TAD groups. Protraction rates as well as overall treatment times were comparable (0.77 mm/month vs. 0.55 mm/month and 3.02 years vs. 2.67 years, respectively). Canine relationships were maintained or improved toward a class I in 82.85% of the Herbst sample, compared to in 66.7% of the TAD sample. Emergency visits occurred in 80.1% of the Herbst group, with cementation failures or appliance breakages as the most common reasons. CONCLUSION: The Herbst device could be a viable modality in cases with missing mandibular premolars where maximum anterior anchorage is desired, or if patients/parents are resistant to TADs. Furthermore, they could be beneficial in skeletal class II patients with mandibular deficiency who also need molar protraction. However, the increased incidence of emergency visits must be considered when treatment is planned.

Evaluation of anchorage loss after en masse retraction in orthodontic patients with maxillary protrusion using friction vs frictionless mechanics: randomized clinical trial.

OBJECTIVES: To evaluate anchorage loss after en masse retraction in bimaxillary dentoalveolar protrusion patients using friction vs frictionless mechanics. MATERIALS AND METHODS: Thirty patients with bimaxillary dentoalveolar protrusion needing extraction of upper first premolars and en masse retraction with maximum anchorage were included in this two-arm, parallel, single-center, single-blinded randomized clinical trial with a 1:1 allocation ratio using fully sealed opaque envelopes. Friction group retraction utilized elastomeric power chain between miniscrews and hooks crimped mesial to upper canines on 17 × 25 stainless steel archwire. Frictionless group used customized T-loop springs loading upper first molars indirectly anchored to miniscrews. Activation was every 4 weeks until full retraction. The primary outcome assessed was anchorage loss evaluated at cusp tip and root apex of the first molar. First molar rotation, incisor tip and torque, and root resorption of anterior teeth were evaluated on digital models and cone beam computed tomography taken before and after space closure. RESULTS: Anchorage loss at crown of first molar was significantly more in frictionless group by 2.1 mm (95% CI = -0.4 to 3.5), (P = .014), while there was no significant difference in anchorage loss at root apex between groups. Significant mesial in molar rotation of 6.672° (95% CI = 12.2-21.2), (P = 0.02) was greater in the frictionless group. Both groups showed comparable tip, torque, and root resorption values. No severe harms were reported. There was mild gingival overgrowth and inflammation in the frictionless group due to T-loop irritation. CONCLUSIONS: Extra anchorage considerations are needed during en masse retraction when frictionless mechanics is implemented as higher anchorage loss and molar rotation were detected. No difference in tip, torque, and root resorption was observed.

Homemade CAD-CAM surgical guide for palatal mini-screw insertion for maxillary molar distalization providing anchorage. A two times original protocol / Pose de mini-vis palatines par chirurgie guidée à l'aide d'un guide CFAO in-office. Description d'un protocole original en deux temps.

Introduction: Temporary Anchorage Devices have revolutionized our approach to anchorage management. However, their placement may carry risks, such as root perforation, damage to the periodontal ligament, buccal-nasal communication, etc. The aim of this article is to describe an original protocol in two times for the placement of a palatal mini-screw through guided surgery using a guide created by Computer-Aided Design and Manufacturing (CAD/CAM) followed by the transfer of placement information to the laboratory for the fabrication of a Custom Medical Device (CMD) for distalization. Materials and Methods: A two-stage protocol is described and illustrated step by step. Phase 1 comprises 7 steps (including superimposition of maxillary cast and profile teleradiography, surgical tray design), followed by phase 2, which involves 3 final steps (including production of impression for laboratory, production of laboratory model with transfer of mini-screw position). Results: Although the position of the mini screws remains precise, a discrepancy between the planning and the intraoral situation exists. The addition of a second step therefore enables the distalization appliance to be fitted precisely and without pitfalls. Finally, this protocol ensures safe placement, making work easier for the practitioner and, ultimately, for the patient. Conclusion: In a two-stage process, the placement of palatal mini screws through guided surgery using a guide created by CAD/CAM followed by the transfer of this information to the laboratory for the fabrication of a CMD for distalization proves to be a relevant approach.

Introduction: Les dispositifs d'ancrage temporaires ont révolutionné notre vision de la gestion de l'ancrage. En revanche, leur mise en place peut comporter certains risques (perforation radiculaire, communication bucco-nasale, lésions vasculaires…). Cet article vise à décrire un protocole original, en deux temps, de pose de mini-vis palatine par chirurgie guidée à l'aide d'un guide réalisé par conception et fabrication assistée par ordinateur (CFAO) in-office suivie du transfert des informations de pose au laboratoire pour la confection d'un appareil de distalisation. Matériel et méthodes: Un protocole en deux temps est décrit pas à pas. Le temps 1 comprend sept étapes (dont le placement virtuel des mini-vis et la création de la gouttière chirurgicale), suivi du temps 2 qui implique trois étapes (dont la réalisation de l'empreinte pour le laboratoire et l'élaboration du modèle de laboratoire avec transfert de la position des mini-vis). Résultats: Bien que la pose puisse être considérée comme précise, une différence existe entre la planification et la situation clinique. L'apport d'un second temps améliore l'adaptation de l'appareil de distalisation. Enfin, ce protocole offre une pose sécurisée et apporte ainsi un confort de travail pour le praticien et, in fine, pour le patient. Conclusion: Réalisée en deux temps, la pose de mini-vis palatine par chirurgie guidée à l'aide d'un guide réalisé par CFAO in-office suivie du transfert de cette information au laboratoire pour la confection d'un appareil de distalisation s'avère être une approche pertinente.

Periodontal evaluation after maxillary expansion with a tooth-bone-borne expander in growing patients : A randomized clinical trial.

PURPOSE: This two-arm parallel randomized controlled trial aimed to evaluate and compare periodontal changes due to rapid maxillary expansion (RME) using tooth-bone-borne and tooth-borne devices in growing patients via clinical examinations and cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Forty-two eligible patients (aged 11-14 years; transverse maxillary deficiency, posterior crossbite) were screened and divided into two groups based on the treatment received (randomization was performed using computer-generated numeric sequences): hybrid hyrax tooth-bone-borne group (TBB) and hyrax tooth-borne group (TB). The primary outcome was the change in cortical bone thickness (by CBCT). In addition, the clinical attachment level (CAL), gingival recession, and bleeding were assessed. Both examinations were performed before and 3 months after the activation phase. Intergroup comparisons were performed using analysis of covariance (ANCOVA; P < 0.05). RESULTS: Twenty-one patients (12 girls and 9 boys; mean initial age, 13.3 years) were included in the TBB group and 21 (5 girls and 16 boys; mean initial age, 13.2 years) were included in the TB group. The TB group exhibited a decrease in buccal bone thickness in the first premolars and first molars at all three evaluated levels. Specifically, tooth 14 at 3 mm from the enamel-cement junction showed a significant width reduction (0.7 mm; p < 0.001), accompanied by a notable increase in palatal cortical thickness at 6 mm of enamel-cement junction (1.13 mm; p < 0.001). CONCLUSIONS: RME resulted in buccal bone thickness reduction at the first premolar with hyrax treatment. In the molar region, both devices resulted in cortical bone alterations that were less pronounced in the TBB group.

Active vertical control with skeletal anchorage for optimizing facial profile in a severe Class II high-angle protrusion case.

This case report describes the nonsurgical management of a patient with a Class II skeletal pattern, retrognathic mandible, steep mandibular angle, maxillary vertical excess, and lip incompetence. The treatment approach involved orthodontic mechanics supported with skeletal anchorage to achieve maximal intrusion and retraction of the dentition. A novel elastic hanging rack appliance, supported by midpalatal miniscrews, was used. A maximal anchorage setup for active vertical control on both arches was illustrated. Significant improvement in the facial profile was achieved with optimal occlusion. Cephalometric analysis revealed successful incisor retraction and intrusion, as well as a forward rotation of the mandible. The treatment outcome illustrates the impact of active vertical control on orthodontic camouflage treatment for severe protrusion.

The influence of oblique sutures and tendon-suture anchorages on tensile resistance and ultimate strength of 4-strand tendon repairs.

This study investigated whether the integration of the oblique sutures contributes to the resistance to gapping in 4-strand flexor tendon repairs. In 72 porcine tendons, we compared repairs incorporating oblique sutures against those without using three distinct anchorage types. The studied suture configurations were longitudinal and oblique, modified Savage and Adelaide, and modified Kessler and Lahey. The number of tendons that formed the first gap or a 2 mm gap at the repair site during cyclic loading, stiffness at the 1st and 20th cycles, gap size between tendon ends and ultimate strength were recorded. No significant differences were found between core sutures with and without oblique sutures except between the modified Savage and Adelaide sutures. The Kessler-type anchorage was inferior in resisting gap formation than simple grasping or cross-locking sutures. We conclude that an oblique suture does not increase the gap resistance of 4-strand tendon repairs when using grasping or Kessler-type anchorages, but it does when using a cross-locking anchorage, such as the Adelaide suture. Simple grasping anchorage is comparable to cross-locking in resisting gap formation.

Variations in the alveolar bone morphology in maxillary molar area: a retrospective CBCT study.

BACKGROUND: This study quantitatively analyzed the anatomic structure of the alveolar bone in the maxillary molar region at three potential locations for Temporary Anchorage Device (TAD) placement. Additionally, the study compared the variability in this region across different age groups, sagittal skeletal patterns, vertical facial types, and sexes. METHODS: In this retrospective cone-beam computed tomography study, the buccal alveolar bone was analyzed in the posterior molar area of 200 patients, the measurement items include buccal alveolar bone height, alveolar bone thickness, interradicular distance, and maxillary retromolar space. RESULTS: Buccal alveolar height was greatest in the U56 region. The interradicular space was largest in the U56 region and increased from the alveolar crest to the sinus floor. Buccal alveolar bone thickness was highest in the U67 region and generally increased from the alveolar crest to the sinus floor. The maxillary retromolar space gradually increased from the alveolar crest to the root apex. CONCLUSIONS: TADs are safest when placed in the buccal area between the maxillary second premolar and the first molar, particularly at the 9 mm plane. The U67 region is the optimal safe zone for TAD placement for maxillary dentition distalization. TADs placement in adolescents can be challenging. Maxillary third molar extraction can be considered for maxillary dentition distalization.

Maxillary impacted canine replacing a central incisor with root resorption: Multidisciplinary treatment in a preadolescent patient.

Maxillary canines are often impacted, which can result in tooth disorders and adversely affect occlusal and facial development. The case report describes complete bilateral impaction of maxillary canines and significant root resorption of a central incisor. The multidisciplinary approach is the optimal strategy for addressing impacted maxillary canines.

Comparative biomechanical analysis of four different tooth- and bone-borne frog appliances for molar distalization : A three-dimensional finite element study.

PURPOSE: The purpose of this study was to analyze the biomechanical effects of four different designs of frog appliances for molar distalization using finite element analysis. METHODS: A three-dimensional finite element model including complete dentition, periodontal ligament, palatine, and alveolar bone was established. Four types of frog appliances were designed to simulate maxillary molar distalization: tooth-button-borne (Type A), bone-borne (Type B), bone-button-borne (Type C), and tooth-bone-borne (Type D) frog appliances. A force of 10 N was applied simulating a screw in the anteroposterior direction. To assess the von Mises stress distribution and the resultant displacements in the teeth and periodontal tissues, geometric nonlinear theory was utilized. RESULTS: Compared to the conventional tooth-borne frog appliance (Type A), the bone-borne frog appliances showed increased first molar distalization with enhanced mesiolingual rotation and distal tipping, but the labial inclination and intrusion of the incisors were insignificant. When replacing the palatal acrylic button with miniscrews (Types B and D), more anchorage forces were transmitted from the first premolar to palatine bone, which was further dispersed by the assistance of a palatal acrylic button (Type C). CONCLUSIONS: Compared to tooth-borne frog appliances, the bone-borne variants demonstrated a clear advantage for en masse molar distalization. The combined anchorage system utilizing palatal acrylic buttons and miniscrews (Type C) offers the most efficient stress distribution, minimizing force concentration on the palatine bone.

Numerical Simulation and Experimental Study of Carbon Fiber-Reinforced Polymer Single-Bar Extrusion Anchorage Structure.

The reliable anchorage of carbon fiber-reinforced polymer (CFRP) tendons is a critical issue influencing the stable bearing capacity of bridge cables. This study introduces a novel CFRP single-strand extrusion anchoring structure, where the strand is compressed at its end. By integrating this with internal cone filler wrapping, we create a CFRP multi-strand cable composite anchoring system. This innovative design not only minimizes the overall dimensions of the anchoring system but also significantly improves its anchoring efficiency coefficient. An axisymmetric model was developed using ANSYS finite element software. The radial stress distribution and anchorage efficiency coefficient in the anchorage zone of Φ7 CFRP bar and Φ13.6 extrusion die were analyzed with varying parameters, such as chamfering, outer diameter, and length of the extrusion sleeve, and were validated through static load anchorage tests. The results indicate that the highest anchoring efficiency is achieved when four extrusion sleeves with a chamfer angle of 5°, an outer diameter of Φ14.4, and a length of 15 mm are connected in series, reaching a coefficient of 61.04%. Furthermore, this study proposes an anchorage structure where multiple extrusion sleeves are connected in series and sequentially compressed to overcome the limitations of increasing anchorage length for enhancing the anchorage coefficient. The test results demonstrate that with equal total anchorage length, connecting four 15 mm extrusion sleeves in series enhances the anchorage efficiency coefficient by 24.98% compared to a single 60 mm extrusion sleeve structure.

An Enhanced Numerical Calculation Method to Study the Anchorage Performance of Rebars.

When modelling the anchorage performance of rebars with the tri-linear law, the calculation process of the load-deformation relation is complicated. The reason is that when the rebar-grout interface entered the elastic-softening-debonding stage, the softening section length and debonding section length vary simultaneously. To solve this issue, this paper proposes an enhanced numerical calculation method. When the rebar-grout interface entered the elastic-softening-debonding stage, the softening section length was fixed to a specific value. One loop function was created to calculate the debonding section length. With this method, the number of iteration calculations significantly decreased. The credibility of this calculation method was confirmed with experimental results. Two case studies were conducted to compare the load-deformation relation obtained with the original calculation method and enhanced calculation method. The results showed that good consistency existed between the results obtained by those two methods. This finding can significantly improve the calculation efficiency when studying the anchorage performance of rebars. Moreover, this paper provides new insight for users to optimise the modelling process of rebars.

Asymmetric Coupled Binuclear-Site Catalysts for Low-Temperature Selective Acetylene Semi-hydrogenation.

Heterogeneous metal catalysts with bifunctional active sites are widely used in chemical industries. Although their improvement process is typically based on trial-and-error, it is hindered by the lack of model catalysts. Herein, we report an effective vacancy-pair capturing strategy to fabricate 12 heterogeneous binuclear-site catalysts (HBSCs) comprising combinations of transition metals on titania. During the synthesis of these HBSCs, proton-passivation treatment and step-by-step electrostatic anchorage enabled the suppression of single-atom formation and the successive capture of two target metal cations on the titanium-oxygen vacancy-pair site. Additionally, during acetylene hydrogenation at 20 °C, the HBSCs (e.g., Pt1Pd1-TiO2) consistently generated more than two times the ethylene produced by their single-atom counterparts (e.g., Pd1-TiO2). Furthermore, the Pt1Pd1 binuclear sites in Pt1Pd1-TiO2 were demonstrated to catalyze C2H2 hydrogenation via a bifunctional active-site mechanism: initially C2H2 chemisorb on the Pt1 site, then H2 dissociates and migrates from Pd1 to Pt1, and finally hydrogenation occurs at the Pt1-Pd1 interface.

The effect of single versus multiple piezocisions on the rate of canine retraction: a randomized controlled trial.

BACKGROUND: Piezocision is a minimally invasive surgical method aiming to accelerate tooth movement. However, its effect was found to be transient, appertaining to the regional acceleratory phenomenon (RAP). Hence, the aim of the study was to evaluate the effect of single and multiple piezocisions on the rate of orthodontic tooth movement (OTM). Moreover, the impact of both protocols on canine tipping and orthodontically induced inflammatory root resorption (OIIRR) has been assessed. METHODS: Thirty indicated patients for the therapeutic extraction of maxillary first premolars were enlisted in this split-mouth study, and they were randomly split into two equal groups, each including 15 subjects. In the Single Application Group (SAG), one side of the maxillary arch arbitrarily received a single piezocision before the onset of canine retraction, whereas in the Multiple Application Group (MAG), piezocisions were randomly performed on one side, three times on a monthly basis, over the 12-week study period. The contralateral sides of both groups served as the controls. Canine retraction was carried out bilaterally using nickel-titanium closed-coil springs, delivering 150 g of force, and the rate of tooth movement, as well as canine tipping were evaluated on a monthly basis, over a 3-month period. Cone-bean computed tomography scans were also conducted pre- and post- canine retraction, and OIIRR was assessed using Malmgren Index. RESULTS: The reported outcomes revealed a significant increase in the amount of canine retraction, canine tipping, as well as root resorption scores on the experimental sides in both groups SAG and MAG post-retraction (p < 0.001). However, upon comparing the experimental sides in both groups, non-significant differences have been observed between them regarding all the assessed outcomes (p > 0.05). CONCLUSIONS: Single and multiple piezocisions effectively accelerate OTM in comparison to conventional orthodontic treatment, with relative outcomes reported by both intervention frequencies. Accordingly, single piezocision is recommended as an adjunct to OTM. Furthermore, significant tooth tipping as well as a significantly higher root resorption risk accompanies both single and multiple piezocision applications in conjunction with OTM. NAME OF THE REGISTRY: Clinicaltrials.gov TRIAL REGISTRATION NUMBER: NCT05782088 DATE OF REGISTRATION: 23/03/2023 "Retrospectively registered". URL: https://clinicaltrials.gov/ct2/show/NCT05782088.

Space Closure with Different Appointment Intervals: A Split-mouth Randomized Controlled Trial.

Background: Canine retraction has been successful with various force systems and retraction techniques. The appointment interval for force reactivation in canine retraction along the archwire is 4-8 weeks. Aims: The aim was to evaluate the effect of different reactivation intervals on the rate of space closure. Settings and Design: This split-mouth randomized clinical trial recruited 38 patients indicated for the first premolar extraction. Methods: Monthly digital models were acquired for 6 months. The first premolars were extracted, and temporary anchorage devices were placed for maximum anchorage control. The canines were retracted using elastomeric chains which were replaced every 2, 4, 6, or 8 weeks. The monthly rate of canine retraction was measured. The time to space closure was calculated. The secondary outcome was the mesial drift of the first molars. Statistical Analysis: The Kaplan-Meier survival analysis and the Friedman test evaluated and compared the groups. Results: There was no significant difference between the monthly canine retraction rate or the first molar mesial drift between the groups. The mean time to space closure was 5.74 months in the 2-week reactivation group, which was statistically less than the other groups. Conclusions: The 2-week reactivation interval may reduce time to space closure. Direct anchorage control with miniscrews limited anchorage loss significantly.