Effect of Dietary Components on the Shear Bond Strength of Orthodontics Brackets after Thermal Aging

Introduction: The stability of orthodontic brackets throughout orthodontic treatment plays a critical role in the treatment’s effectiveness. The present in vitro study was designed to assess the impact of various dietary components on the performance of orthodontic brackets. Methods: Metal orthodontic brackets were bonded to 66 extracted anterior teeth divided into groups based on the solution type: Milk, Gatorade, Cold Coffee, and a control group using water. Each group consisted of 20 teeth except for the control group, which included six teeth. The bracketed teeth were submerged in their respective solutions for 15 minutes three times daily at different intervals to mimic an in vivo environment and were stored in artificial saliva at room temperature (23?C). The specimens underwent artificial aging through 10,000 cycles of thermocycling (representing one clinical year) between 5?C and 55?C. Shade measurements were taken using a VITA Easy Shade device, capturing the classic shade and L*, a*, and b* values. Delta E values were calculated immediately post-bonding and after 7 days, 1 month, 1, and 2 clinical years. The shear bond strength of each bracket was measured using an ultra-tester machine. Results: After two clinical years, significant differences in ΔE color values were observed across all groups, with the most substantial change noted in teeth immersed in cold coffee. Brackets submerged in milk demonstrated lower shear bond strength than other solutions, whereas the control group exhibited the highest shear bond strength (P = 0.01). Conclusion: The study indicates that dietary components significantly influence tooth color stability and the shear bond strength of orthodontic brackets, underscoring the importance of considering these factors in orthodontic treatment planning.

Research and Analysis on Anti-corrosion of Mountain Photovoltaic Brackets

With the increasing global demand for renewable energy,solar photovoltaic power generation technology has been widely applied in China and even globally.Especially in mountainous areas,complex terrain resources are cleverly utilized in the construction of photovoltaic power stations,but this also brings severe challenges to the anti-corrosion of photovoltaic brackets.This paper focuses on the anti-corrosion technology of mountain photovoltaic brackets,and deeply explores the influence of natural factors such as mountain climate,sandstorms,and precipitation on the corrosion of photovoltaic brackets.The research results show that the key to improving anti-corrosion performance lies in the selection of bracket materials and optimization of coating processes.After comparing various anti-corrosion treatment methods such as hot-dip galvanizing,spray aluminum coating,and new anti-corrosion materials,it is found that nano coating technology exhibits excellent protective effects in corrosive environments.This study is of great significance for promoting the sustainable development of photovoltaic power generation,providing solid theoretical support and practical guidance for the anti-corrosion design of mountain photovoltaic power stations.

Design and Optimization of Solar Photovoltaic Brackets in Mountainous Areas Adapted to Complex Wind Environments

With the increasing global demand for renewable energy,the application of photovoltaic power generation in mountainous areas is gradually increasing.However,the complex wind environment in mountainous areas poses severe challenges to the design and optimization of solar photovoltaic brackets.Traditional design methods are difficult to cope with the changeable wind speed and direction in mountainous areas,resulting in structural instability or material waste.Researchers have identified the key factors affecting wind response through parametric research and dynamic wind response analysis,so as to optimize the brackets design and improve its adaptability and stability in complex wind environments.In this paper,the complexity of wind speed,wind direction and turbulence characteristics in mountainous areas and their influence on brackets design are explored.Through static and dynamic wind load analysis,the geometrical shape and material selection of the bracket are optimized to enhance its wind resistance.The application of multi-objective optimization model and intelligent optimization algorithm provides an effective solution for the design of solar photovoltaic brackets,ensuring their safety and reliability in complex wind environments.

Research on semi-solid thixoforming process of AZ91D magnesium alloy brackets for generators in JH70-type motorbikes

The investment on semi-solid die casting processes of AZ91D magnesium alloy brackets for generators in JH70-type motorbikes is introduced. The processes of low super-heat and cooling slope for the preparation of billets with non-dendritic microstructure, the remelting of billets for thixoforming and the parameters in the process of semi-sohd thixoforming have been researched. The results show that primary billets with non-dendritical structures can be prepared by forming great amount of nuclei in melt via the process of low super heat. By optimizing the remelting process through adjusting the current of the induced equipment, semi-solid billets with a structure of spherical grains were obtained from the primary billets with non-dendritical structure. The range of 580℃ to 583℃ is the proper remelting temperatures by which the billets have an expected thixotropy and can be transferred to a die-casting machine. The optimized parameters of semi-solid forming in a die-casting machine are as follows： the area of the ingate in the die is 383.5 mm^2, the speed of the pierce of the machine 5 m/s, the shot pressure of the pierce 75 MPa, and the maintenance pressure of the pierce 350 MPa. The castings of brackets for supporting generators in JH70 type motorbikes were formed by adopting the optimized processes and parameters mentioned above.

The Evaluation of a Resin-modified Glass Ionome Cement for Bonding Orthodontic Brackets

To evaluate the shear bond strength（SBS） and bond failure interface after the debonding of orthodontic brackets with a resin-modified glass ionomer cement（RMGIC） under six bonding conditions, 140 premolar teeth were randomly divided into seven groups. The brackets of all groups, except for control group, were bonded using a RMGIC. The teeth were debonded using a universal testing machine. The shear bond strength, adhesive remnant index （ARI） and enamel fracture were examined for each debonding. A significant difference existed in SBS under wet and dry conditions in two groups of Fuji Ortho LC. Different degree of enamel fracture was seen in groups of Fuji Ortho LC（dry/37% phosphoric acid treated） after debonding. Bond failed predominantly at the enamel-adhesive interface, except for phosphoric acid treated groups. The RMGIC achieve a clinically effective adhesion in orthodontics under different bonding conditions.

Clinical assessment of demineralization and remineralization surrounding orthodontic brackets with FluoreCam

Objective: To determine quantitatively the amount of demineralization and the ability of commercially available products and an experimental cream to inhibit or reverse orthodontic related demineralization.Methods: A total of 20 patients who were 25–35 years old and having orthodontic treatment for 6–8 months were chosen.Caries risk assessments were done for each patient and ones with "moderate risk" were included.Patients with fixed orthodontic appliances were divided into 4 groups(5 patients each) including one control and 3 study groups.All patients used same toothpaste 2 times a day during the 3 weeks study period.Additional to the toothpaste first study group used MI Paste Plus(GC, Tokyo, Japan), second study group used Remin Pro(Voco, Cuxhaven, Germany) and third group used an experimental remineralizing cream per day for 3 weeks.Maxillary central and lateral incisors of each patient were examined by FluoreCam(Daraza Therametric Technologies, USA) device.The examinations were performed at baseline and at the end of 1st, 2nd and 3rd weeks.Results: According to the FluoreCam measurements the control group showed significant amount of demineralization at the end of 3 weeks, moreover the amount of demineralization has gradually increased in time.At the end of the study all 3 study groups showed significant amount of remineralization and the amount of remineralization for all the 3 study groups has gradually increased in time.However the amount of remineralization for 3rd study group was lesser than the 1st and 2nd study groups.The remineralization amounts for the 1st and 2 nd study groups were determined to be identical.Conclusions: This study demonstrated that demineralization is measurable around orthodontic brackets and the demineralization can be completely inhibited and/or reversed by the use of commercially available remineralization products.

Bond Strength of Brackets Bonded with Chemically and Light Activated Materials after Thermal Cycling

The aim of this study was to evaluate the bond strength of orthodontic brackets bonded to tooth enamel with different polymer composites after simulated clinical aging, and analyze the enamel/ bond system fracture interface. 80 human premolars, were randomly divided into five groups (n = 16). G1: CO (Concise Ortodontica—3M ESPE), G2: SB (SuperBond—Ortho Source), G3: FMO (Fill Magic Ortodontico—Vigodent), G4: TXT (Transbond XT—3M ESPE) and G5: TP (Transbond Plus Self Etching Primer + Transbond Plus Color Change—3M ESPE). In all groups, the metal orthodontic bracket was bonded to the tooth enamel surface. The specimens were submitted to 3000 thermal cycling baths for 30 s, at temperatures of 5°C, 37°C and 55°C (±1°C). Afterwards they were subjected to shear testing and the results were analyzed by the Student’s-t test (p < 0.05). G1 presented the highest bond strength value, followed by G4 > G5 > G2 > G3. In all groups the majority of the fractures at the interface of the specimens were cohesive, except in G3, which presented the largest number of adhesive fractures. After clinical aging, the chemically activated material (CO) showed higher bond strength than the light activated types (FMO, TXT and TP). The self-etching adhesive system (TP) showed similar bond strength to that of conventional systems (FMO and TXT).

Performance of Different Orthodontic Brackets after Exposure to Dietary Components: An <i>in Vitro</i>Pilot Study

Introduction: The aim of this study was to determine whether there was a significant difference in shear bond strength between metal and ceramic brackets when exposed to acidic dietary components (beverages) and to observe the chromogenic potential of each in vitro. Methods: Metal and clear orthodontic brackets were placed on extracted maxillary second premolars and exposed to select beverages three times daily for four weeks. Shade was taken using a colorimeter device at seven intervals and the shear bond strength of each bracket was recorded. Results: There was a variable change in tooth shade with respect to the various beverages in which they were submerged. Coffee and Dr. Pepper had the most pronounced change, whereas Red Bull and water produced little to none, respectively. Compared to controls, brackets submerged in coffee had the greatest reduction in shear bond strength, followed by Dr. Pepper, then Red Bull. Overall, clear brackets showed higher shear bond strength than metal brackets. Conclusion: Acidic dietary components have a negative effect on the shear bond strength of orthodontic brackets, and more pigmented beverages have a higher chromogenic staining potential.

A Study on the Multi-Objective Optimization Method of Brackets in Ship Structures

The shape and size optimization of brackets in hull structures was conducted to achieve the simultaneous reduction of mass and high stress,where the parametric finite element model was built based on Patran Command Language codes.The optimization procedure was executed on Isight platform,on which the linear dimensionless method was introduced to establish the weighted multi-objective function.The extreme processing method was applied and proved effective to normalize the objectives.The bracket was optimized under the typical single loads and design waves,accompanied by the different proportions of weights in the objective function,in which the safety factor function was further established,including yielding,buckling,and fatigue strength,and the weight minimization and safety maximization of the bracket were obtained.The findings of this study illustrate that the dimensionless objectives share equal contributions to the multi-objective function,which enhances the role of weights in the optimization.

Bonding Orthodontic Ceramic Brackets to Ceramic Restorations:Evaluation of Different Surface Conditioning Methods

The purpose of this study was to compare the shear bond strength and Adhesive Remnant Index of four different veneering ceramic materials to ceramic brackets. Additionallly, a further aim of this study was to overcome the etching using hydrofluoric acid which is noxious and could seriously damage the corneas of the eyes. Two surface conditioning methods of four ceramic materials before bonding brackets were examined: in group 1 an air particle abrasion with 25 μm aluminium trioxide (4 seconds at a pressure of 2.5 bars) and subsequently a silane coupling agent (Espe Sil, 3M Unitek, Monrovia, USA) was applicated on one side of each ceramic specimen (10 per group). In group 2 one side of each sample (20 per group) was etched with 37.0 per cent orthophosphoric acid for two minutes and was followed by a silane application (Espe Sil, 3M Unitek, Monrovia, USA). After this procedure the self-ligating ceramic brackets Clarity SL (3M Unitek, Monrovia, USA) brackets were bonded to the ceramic blocks and a thermocycling process started (5°C - 55°C, 6000 cycles). Then, shear bond strength and Adhesive Remnant Index (ARI) were measured. To determine statistical differences Oneway-ANOVA and Tukey Post-hoc test were performed. Hydrofluoric acid seems not to be justifiable anymore for preparing the surface of dental ceramic restorations before bracket bonding. Sandblasting with 25 μm aluminium trioxide and the use of orthophosphoric acid (37.0 per cent) seem to prepare the surface of ceramic restoration sufficiently before ceramic bracket bonding. The found level of shear bond strength values seems to be sufficient for bonding ceramic brackets to ceramic restorations.

Application of mobile photography with smartphone cameras for monitoring of orthodontic correction with dental BRACKETS

This research was to observe patients,who underwent orthodontic tooth alignment correction with dental brackets,for the purpose of early detection of white spots(early satge of caries)and dynamic measurement of distance between teeth edges based on the digital photographs taken with a smartphone Sony Xperia S.Color reading was realized taking into account the adjustment of color features of a standard ceramic surface(tile)that was selected during the dental brackets installation period,the photo of which was taken simultaneously during the dynamic observation period.The color scale RGB was transformed into CIE L*a*b scale of color measurement with regard to the correction of RGB components of image by usage of correction coefficient for calibration tile surface RGB characteristics.The expert appraisal showed sensitivity of proposed method was between 88.7%and 96.2%(the mean 93.1%)and specificity between 68.4%and 84.2%(the mean 75.4%).The positive predictive value was between 89.5%and94.0%(the mean 91.5%);and the negative predictive value was between 72.7%and 86.7%(the mean 80.6%).The measurement of the distance between teeth edges during the first 10 days following the brackets installation was carried out using a self-scalable ruler that was calibrated,according to the standard sizes of the dental bracket system components.The Android application of self-scalable ruler was developed using Java.The development of a pronounced pain syndrome was observed when the velocity of distance changes between teeth edges was rather high-0.051+0.004 mm/day.The improvement of efficiency of the suggested method is expected due to application of illumination standards during the shooting period.

Application Strategies of the Bracket Set in Modern Architectural Design

The Bracket Set(dougong)is an important aspect of traditional Chinese architecture known for its exquisite structure,complexity,and rich variations.This design element has been used since the Qin and Han Dynasties and is still prevalent today.It highlights hierarchy and spiritual connotations in the design of a building.This article explores the application of Bracket Set elements in modern architectural design.It analyzes the specific application strategies of this design element,highlighting its value in modern architecture.The goal is to provide modern architectural designers with multiple perspectives and strategies to fully utilize the advantages of Bracket Set elements in architectural design and enhance the artistic value of their work.

BracKet间接粘着法的临床应用

目的:提高固定矫治器中BracKet的粘接精度,使矫治器发挥最佳矫治疗效。方法:先将BracKet精确地粘接在石膏模型上,后用0.5 mm胶模制做转移模托,将BracKet再转移到模托上。最终将BracKet精确地粘着于牙面上。结果:通过临床观察证明BracKet间接粘着法克服了直接粘着法中BracKet位置不准确,BracKet的粘接高度和角度不易控制的缺点,能使BracKet精确地粘与牙面。结论:随着固定矫治器的不断发展,临床上对BracKet的粘着精度越来越高,为了达到此目标,提高矫治疗效,采用BracKet间接粘着法将托槽的粘着精度大大提高。

高精度铅同位素比值MC-ICP-MS测试方法及土壤标准物质铅同位素组成

利用多接收电感耦合等离子体质谱仪(MC-ICP-MS)精准测定了国家土壤标准物质的铅同位素比值,研究了MC-ICP-MS测定铅同位素时的分馏效应,发现仪器存在非质量分馏效应,应用Baxter法和标准与实际样品的交叉组合法(SSB)校正仪器的质量和非质量分馏,校正后NIST SRM 981标准溶液的铅同位素比值具有较高的准确度和精确度。采用MC-ICP-MS测定了3个国家土壤标准物(GBW07564、GBW07406a、GBW07980)的铅同位素比值。对土壤进行微波消解和纯化,回收率大于98%,全流程空白小于0.22 ng。GBW07564铅同位素的^(206)Pb/^(204)Pb为19.9603±0.0303、^(207)Pb/^(204)Pb为15.7675±0.0061、^(208)Pb/^(204)Pb为39.0868±0.0264(n=9,2SD);GBW07406a铅同位素的^(206)Pb/^(204)Pb为18.8024±0.0018、^(207)Pb/^(204)Pb为15.7442±0.0025、^(208)Pb/^(204)Pb为39.1943±0.0086(n=9,2SD);GBW07980铅同位素的^(206)Pb/^(204)Pb为18.6142±0.0057、^(207)Pb/^(204)Pb为15.7378±0.0044、^(208)Pb/^(204)Pb为38.9629±0.0153(n=9,2SD)。这些土壤标准物质的^(206)Pb/^(207)Pb分别为1.2659±0.0014、1.1942±0.0001、1.1828±0.0001(n=9,2SD),^(208)Pb/^(206)Pb分别为1.9582±0.0018、2.0845±0.0003、2.0932±0.0002(n=9,2SD),大致在自然界土壤铅同位素^(206)Pb/^(207)Pb(大于1.17)、^(208)Pb/^(206)Pb(小于2.11)变化范围内,且容易获得,化学和铅同位素组成均一,适合作为监控土壤铅同位素化学及质谱分析数据可靠性的同位素土壤标准物质。

深厚软土且空间受限条件下桩板结构现浇梁支架方案设计

桩板结构具有结构简单、受力明确等优点,能够减少材料用量,降低工程造价,在跨越小面积的河流、道路或其他交通设施时,得到广泛使用。莲鹤大道项目与珠肇高铁并行段,设计采用桩板结构桥梁,共计3100m,地质条件复杂,淤泥质软土深厚,梁底距离地面空间受限,现浇梁施工难度大。设计方建议采用贝雷梁+工字钢结构形式支架方案,由于部分梁底距离地面净空不足,该方案向下反开挖最多达3.0m,施工工效低,投入大。本文针对不同净空条件,研究了三种支架结构,满足共线段3.1km桩板结构现浇梁施工,提高了施工工效,降低了施工成本,为后续类似工程提供了参考。

Numerical simulation and optimization of shell mould casting process for leaf spring bracket

Although the shell mould casting process has a wide range of application in many fields,the prediction of casting defects is still a problem.In the present work,a typical leaf spring bracket casting of ZG310-570 was fabricated by shell mold casting.The finite element model and ProCAST software were utilized for simulating the filling and solidification processes of the casting;and the formation mechanism of the gas pore,and shrinkage porosity defects were analyzed.The results indicate that the gas pore and shrinkage porosity defects are formed due to air entrapment,insufficient feeding and non-sequential solidification.Subsequently,through changing the position of risers,adding a connecting channel between the risers,and setting blind risers at the U-shaped brackets,an optimized gating and feeding system was established to improve the quality of the casting.After optimization,the gas pore and shrinkage porosity defects of the leaf spring bracket casting are effectively eliminated.The experiment results with the optimized casting process are in good agreement with the numerical simulation,which verifies the validity of the finite element model in the shell mould casting.

Structural Stress Monitoring and FEM Analysis of the Cutting Operation of the Main Bracket of A Semi-Submersible Platform

For a semi-submersible platform in repair, the eight old main brackets which connect columns with pontoons need to be replaced by new ones. In order to ensure the safety of the cutting operation of the old main bracket and calculate the initial stress condition of new main bracket, the structural stress monitoring of eight key spots is carried out, and then the calibrated finite element model is established according to the field monitoring results. Before cutting the main bracket and all associated structures, eight rectangular rosettes were installed, and a tailored cutting scheme was proposed to release the initial stress, in which the main bracket and associated column and pontoon plates were partly cut. During the cutting procedure, the strains of the monitoring spots were measured, and then the structural stress of the monitored spots were obtained. The stress variation characteristics at different spots during the initial cutting operation were shown and the initial stress condition of the monitored spots was figured out. The loading and support conditions of the semi-submersible platform were calibrated based on the measured initial stress condition, which made the finite element model more credible. The stress condition with the main bracket and associated structures being entirely cut out is analyzed by the Finite Element Method (FEM), which demonstrates the cutting operation to be safe and feasible. In addition, the calibrated finite element model can be used to calculate the initial stress condition of the new main bracket, which will be very helpful for the long-term stress monitoring on the main bracket.

Fatigue Life Analysis of the Hoist Bracket for Rescue Helicopters

Helicopter rescue has become an important way of life and property relief in modern society.The structure and parameters of the helicopter hoist bracket influence the convenience,safety and reliability of the rescue operation for the lifeguard and hoistman.Based on fatigue analysis theory and ANSYS workbench software,the fatigue life analysis of the hoist bracket is carried out.First,the structure of the hoist bracket is modeled according to the body standard of the hoistman and lifeguard.Then an approach is presented to obtain the S-N curve of the hoist bracket by modifying the S-N curve of the bracket material based on Goodman curve while considering the influences of the shape,size,surface state,loading conditions and the average stress.Further,based on the ANSYS workbench analysis,the life and safety nephogram of the bracket under the fluctuating cyclic load can be obtained.Finally,the designed bracket is analyzed with the proposed method.The cycles number of the bracket is greater than 107 under the extreme conditions of the pulsating cyclic load,which may be considered as the unlimited life and meets the requirement of the fatigue strength.

A Recursive Approach to the Kauffman Bracket

We introduce a simple recursive relation and give an explicit formula of the Kauffman bracket of two-strand braid link . Then, we give general formulas of the bracket of the sequence of links of three-strand braids . Finally, we give an interesting result that the Kauffman bracket of the three-strand braid link is actually the product of the brackets of the two-strand braid links and . Moreover, a recursive relation for is also given.

Fatigue Crack Analysis on the Bracket of Sanding Nozzle of CRH5 EMU Bogie

Aiming at the fracture of the bracket of sanding nozzle of CRH5 EMU bogie, the fatigue strength analysis and modal analysis of the bracket were conducted according to En13749 and BS7608 standards, and the track excitation during the vehicle running was thoroughly analyzed. The cause leading to the fracture of the bracket was found and the bracket was redesigned.