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.

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.

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.

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).

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.

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.

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.

Maps Preserving Zero Lie Brackets on a Maximal Nilpotent Subalgebra of the Symplectic Algebra

Let F be a field with char F = 2, l a maximal nilpotent subalgebra of the symplectic algebra sp（2m,F）. In this paper, we characterize linear maps of l which preserve zero Lie brackets in both directions. It is shown that for m ≥ 4, a map φ of l preserves zero Lie brackets in both directions if and only if φ = ψcσT0λαφdηf, where ψc,σT0,λα,φd,ηf are the standard maps preserving zero Lie brackets in both directions.

Structural, Visual, or Iconic： Transmutations of Wooden Brackets in Modern China

Together with pillars and roof, the bracket set is one of the most fundamental structural components of traditional timber-frame architecture in China. Not only structurally indispensable, it was also emblematic of specific building styles developed through history. Entering the modem era, however, its architectural validity was overturned by the use of modem technology and building materials, rendering brackets merely a visual and decorative motif. This paper contends that it was precisely when the bracket set lost its structural significance that it began to be discussed in ways that endowed it with layers of cultural meaning in the context of modem China. Examining its modem appropriations in materials other than wood throughout the twentieth century, the paper explores shifting meanings of brackets in their continuous transmutations from a reminder of a defunct component in the building tradition to a nostalgic sign for an irretrievable architectural past.

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.

Complex brackets and balanced complex 1st-order difference polynomials in 4-dimensional Minkowski space

This paper investigates complex brackets and balanced complex 1st-order di?erence (BCD) polynomials. Then we propose an algorithm of O(n log n) complexity to check the equality of brackets. It substitutes exponential algorithms before. Also, BCD polynomials have some usages in geometric calculation.

A mask R-CNN based method for inspecting cable brackets in aircraft

In the aviation industry,cable bracket is one of the most common parts.The traditional assembly state inspection method of cable bracket is to manually compare by viewing 3 D models.The purpose of this paper is to address the problem of inefficiency of traditional inspection method.In order to solve the problem that machine learning algorithm requires large dataset and manually labeling of dataset is a laborious and time-consuming task,a simulation platform is developed to automatically generate synthetic realistic brackets images with pixel-level annotations based on 3 D digital mock-up.In order to obtain accurate shapes of brackets from 2 D image,a brackets recognizer based on Mask R-CNN is trained.In addition,a semi-automatic cable bracket inspection method is proposed.With this method,the inspector can easily obtain the inspection result only by taking a picture with a portable device,such as augmented reality(AR)glasses.The inspection task will be automatically executed via bracket recognition and matching.The experimental result shows that the proposed method for automatically labeling dataset is valid and the proposed cable bracket inspection method can effectively inspect cable bracket in the aircraft.Finally,a prototype system based on client-server framework has been developed for validation purpose.

External apical root resorption and the release of interleukin-6 in the gingival crevucular fluid induced by a self-ligating system

The aim of this study was to investigate the amount of external apical root resorption (EARR) and the release of interleukin (IL)-6 in the gingival crevicular fluid (GCF) in subjects treated with a low-force low-friction system. Sixty patients were assigned to two groups of thirty patients for each: one group received treatment with self-ligating brackets and the other with conventional ligated edgewise brackets. All patients were treated with extraction of the maxillary first premolars. The EARR of the maxillary central incisors was evaluated on the periapical radiographs and cephalograms, taken before and after orthodontic treatment. The GCF was also collected non-invasively from the mesial and distal sides of central incisors by using filter paper strips before and after orthodontic treatment. Enzyme-linked immunosorbent assay (ELISA) kits were used to determine the IL-6 levels in the GCF samples. A significant difference was found in the amount of EARR between the patients with self-ligating brackets and conventional brackets. The mean amount of EARR was significantly lower for self-ligating brackets than conventional brackets (p < 0.05). The GCF levels of IL-6 for the patients with self-ligating brackets appliance were significantly lower than for those with the conventional brackets (p < 0.05). These results show that the mean amount of EARR and the GCF levels of IL-6 were significantly lower in the patients treated using low-force low-friction appliances than conventional brackets. Therefore, self-ligating brackets may be a useful system for reducing inflammation and EARR.

The Influence of Surface Conditioning of Ceramic Restorations before Metal Bracket Bonding

The aim of this study was to compare the shear bond strength and Adhesive Remnant Index of four different veneering ceramic materials to metal brackets. Additionally, it should be examined whether it is possible to overcome the etching method using hydrofluoric acid which is noxious. Instead of this treatment, air particle abrasion with 25 μm aluminium trioxide, silane coupling application and etching with 37.0 per cent orthophosphoric acid as pre-treatment procedures of the veneering ceramics before bonding was investigated. 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 (10 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 metal brackets SmartClip (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. The level of significance was set at α = 0.05. On the basis of the results of the current study, it could be concluded that sandblasting with 25 μm aluminium trioxide and the use of orthophosphoric acid (37.0 per cent) seem to prepare the surface of the ceramic restoration sufficiently before bracket bonding. The found level of shear bond strength values seem be sufficient for bracket bonding. Hydrofluoric acid seems not to be justifiable anymore for preparing the surface of dental ceramic restorations before bracket bonding.

A New Formulation of Quantum Mechanics

A new formulation of quantum mechanics based on differential commutator brackets is developed. We have found a wave equation representing the fermionic particle. In this formalism, the continuity equation mixes the Klein-Gordon and Schrodinger probability density while keeping the Klein-Gordon and Schrodinger current unaltered. We have found time and space transformations under which Dirac’s equation is invariant. The invariance of Maxwell’s equations under these transformations shows that the electric and magnetic fields of a moving charged particle are perpendicular to the velocity of the propagating particle. This formulation agrees with the quaternionic formulation recently developed by Arbab.

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。

Effect of self-ligating bracket appliance on the periodontal tissues in patients with chronic periodontitis after orthodontic treatment

Objective:To explore the effect of self-ligating bracket appliance on the periodontal tissues in patients with chronic periodontitis after orthodontic treatment.Methods:A total of 56 patients with chronic periodontitis who were admitted in our hospital were included in the study and divided into the observation group and the control group according to different treatment protocols. The patients in the observation group were given self-ligating brackets, while the patients in the control group were given traditional brackets. The periodontal tissues and tooth motility (TM) before and after treatment in the two groups were observed and recorded. IL-1βand TNF-α levels in the gingival crervicular fluid (GCF) before and after treatment in the two groups were detected.Results:PD, CAL, SBI, and PLI after treatment in the two groups were significantly reduced, while GR was significantly elevated when compared with the control group. PD, CAL, SBI, and PLI after treatment in the observation group were significantly lower than those in the control group, while GR was significantly higher than that in the control group. TM after treatment in the two groups was significantly improved, among which the number of 0° TM was significantly increased, while the number ofⅠ°-Ⅲ°TM was significantly reduced. IL-1β and TNF-α levels in GCF after treatment in the two groups were significantly reduced when compared with before treatment. IL-1β and TNF-α levels in GCF after treatment in the observation group were significantly lower than those in the control group.Conclusions:The self-ligating brackets can effectively improve the periodontal tissues and TM in patients with chronic periodontitis, and reduce the levels of inflammatory cytokines in periodontal tissues, with an accurate efficacy.

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.

An Integrating Algorithm and Theoretical Analysis for Fully Rheonomous Affine Constraints: Completely Integrable Case

This paper develops an integrating algorithm for fully rheonomous affine constraints and gives theoretical analysis of the algorithm for the completely integrable case. First, some preliminaries on the fully rheonomous affine constraints are shown. Next, an integrating algorithm that calculates independent first integrals is derived. In addition, the existence of an inverse function utilized in the algorithm is investigated. Then, an example is shown in order to evaluate the effectiveness of the proposed method. By using the proposed integrating algorithm, we can easily calculate independent first integrals for given constraints, and hence it can be utilized for various research fields.

Inverse Transformation of Elliptical Relative State Transition Matrix

A new set of relative orbit elements (ROEs) is used to derive a new elliptical formation flying model in previous work. In-plane and out-of-plane relative motions can be completely decoupled, which benefits elliptical formation design. In order to study the elliptical control strategy and perturbation effects, it is necessary to derive the inverse transformation of the relative state transition matrix based on relative orbit elements. Poisson bracket theory is used to obtain the linear transformations between the two representations: the relative orbit elements and the geocentric orbital frame. In this paper, the details of these transformations are presented.