Bracket Combinations Research Articles

NVH numerical analysis of the mounting layout of hydrostatic transmissions in continuously variable transmissions

The present work proposes a numerical approach to model the dynamic behavior of the mounting layout of hydrostatic transmissions in continuously variable transmissions for off-road vehicles. The methodology takes advantage of a finite element model constituted by a rigid body, representing the hydrostatic transmission, connected to the overall transmission frame through a combination of torsional couplings, rolling-element bearings and brackets, considered as flexible components. Bearings, in particular, are substituted with nonlinear springs, while brackets and frames are 3D meshed according to the actual geometry of the system. The model allows to estimate the frequency dependent forces applied on the frame in reference to the loads generated within the hydrostatic transmission. The method is applied on a case study, showing that the torsional joints play a relevant role on the overall NVH behavior of the system and their kinematic characteristics should be carefully defined to tune the loads transmitted on the transmission frame.

Evaluation of the frictional resistance between different bracket types, archwires and ligation materials: An in-vitro study

In orthodontic treatment, brackets need to slide along the archwire to allow for alignment of the teeth. The lesser the friction between the bracket and the archwire, the easier it is to align the teeth and the lighter the forces required to make such movements. In recent years, patients’ esthetic demands have driven the field of orthodontics to find alternatives to conventional stainless steel bracket systems. While ceramic brackets meet the esthetic demands, their inferior frictional characteristics have always been an issue for orthodontists.The present in-vitro research study evaluates and compares the frictional resistance between various types of brackets, archwire materials and ligation methods. The purpose of the study was to equate the frictional resistance among 12 different groups using the universal testing machine, so as to recognize the factors involved in the in-vitro appraisal of resistance to sliding (RS) and inferring their clinical implications. In this study, 120 pre-adjusted edgewise upper central incisor brackets with MBT 0.022″ slot were used, which included 40 standard metal brackets, 40 ceramic brackets, 20 self-ligating metal brackets and 20 self-ligating ceramic brackets. 0.019″ x 0.025″ SS (stainless steel) archwires, esthetic archwires, Teflon-coated ligatures and conventional elastic modules to ligate the archwire to the brackets except in self-ligating brackets, were used. The average frictional resistance of Group A10 was the minimum succeeded by A9, A12, A4, A11, A8, A3, A7, A2, A6, A1 and A5. In the comparison of the mean frictional resistance of 12 different groups, the ANOVA test showed noticeably different frictional resistance amongst the groups (F=745.80, P< 0.001). Self-ligating metal bracket combinations with different archwires showed a significantly smaller magnitude of friction than self-ligating ceramic, metal and ceramic bracket combinations. Teflon-coated ligature combinations possess less friction in comparison with conventional elastomeric module combinations.

The Efficacy of Accelerating Orthodontic Tooth Movement by Combining Self-Ligating Brackets With One or More Acceleration Methods: A Systematic Review.

This review aimed to evaluate the effectiveness of using one or more acceleration methods with self-ligating brackets to accelerate orthodontic tooth movement in adults and the associated effects of these interventions. An electronic search of the following databases (PubMed, Scopus, Google Scholar, EMBASE) was performed (From January 1990 to November 2021). ClinicalTrials.gov and the International Clinical Trials Registry Platform were also electronically searched to findany unpublished studies and ongoing trials. The selected randomized controlled trials (RCTs) involved adult patients treated using self-ligating brackets combined with one or more acceleration methods compared with self-ligating brackets or conditional brackets alone. The risk of bias was assessed using Cochrane's risk of bias tool. A total of seven RCTs and one controlled clinical trial (CCT) were included in this review. Combining self-ligating brackets with flapless corticotomy, low-level laser therapy (LLLT), and infrared light accelerated orthodontic movement by 43% and 50% for surgical methods, 20-50% forLLLT, and 22% for infrared light. Regarding side effects on periodontal tissues, neither flapless corticotomy nor low-frequency vibrational forces caused any damage. Combining self-ligating brackets and flapless corticotomy, low-level laser, or infrared light effectively accelerated orthodontic movement by 20% to 50 %. In contrast, the combination of self-ligating brackets with vibrational forces did not affect speeding tooth movement. The acceleration methods did not have any side effects on the periodontal tissues, but the available evidence was insufficient. There is a need for further primary research regarding the effectiveness of combining self-ligating brackets with acceleration methods and the possible untoward side effects.

Frictional Resistance in Orthodontics -A Review

This article reviews the frictional resistance of archwires based on the cross section, microscopic structure and stiffness. Bracket factors like slot width and depth and material influencing friction. Different types of ligation influencing friction. Role of saliva, biofilm and wire bracket combinations on friction. Friction in wire, bracket and ligation combination.

Esthetics of Orthodontic Appliances: Objective Evaluation by Spectrophotometry vs Subjective Evaluation Using the Visual Analog Scale Method

In this study, we quantified the color of brackets and archwire appliances for an objective evaluation and investigated its relationship with subjective esthetic evaluation. Five types of commercially available brackets (ceramic brackets C1, C2, and C3; plastic brackets P1 and P2) and three types of archwires (coated nickel-titanium archwires W1, W2, and W3) were used. The reflectance (%) and color (lightness: L*, hue: a*, b*) of each sample were quantified using a spectrophotometer (n = 5). Fifteen combinations of brackets and archwires were used. The esthetic evaluation was performed using the visual analog scale (VAS) method, and responses were obtained from 30 laypersons and 15 orthodontists. The mean VAS score was calculated, and the relationship between the reflectance and color of the bracket and archwire was discussed. The reflectance and L* of the brackets showed significantly higher values for C3 and C1 than for the others and lower values for P1 and P2. The reflectance and L* of the archwire showed significant differences among all samples. There was a high positive correlation between the reflectance and L*. There were statistically significant positive correlations between the layperson and orthodontist groups, between the VAS score and reflectivity, and between VAS score and L*. Our results showed that as the lightness and reflectance of the brackets and archwires increased, the subjective evaluation concerning their esthetic value was higher. It is extremely difficult to evaluate esthetics despite the fact that patients' demands for esthetics have been increasing in recent years. If a method for evaluating esthetics is established, it should help in the development and selection of esthetic devices. The results of this study will facilitate the development of future study designs.

Comparative in vitro analysis of the sliding resistance of a modern 3D-printed polymer bracket in combination with different archwire types.

ObjectivesTo analyse the sliding resistance of a modern 3D-printed polymer bracket combined with different archwire types and to compare the results with conventionally used polymeric, ceramic and metal brackets. It was of further interest which bracket-archwire combination could be best qualified for clinical use.Materials and methodsThe sliding behaviour was tested using an orthodontic measurement and simulation system (OMSS) for the use of two bracket types of the polymer, ceramic and metal group in combination with a 0.016 inch × 0.022 inch and 0.017 inch × 0.025 inch archwire of nickel-titanium (NiTi), titanium-molybdenum alloy (TMA) and stainless steel. Six bracket types were combined with six different archwire types and compared to each other.ResultsThe sliding resistance showed significant differences between various the bracket-archwire complexes. The combination of 3D-printed polymer brackets with both steel archwire cross-sections showed the least values of sliding resistance (average 23–29%), while the combination of ceramic brackets with TMA archwires presented the highest (average 47%).ConclusionsThe present study could show that modern 3D-printed bracket materials can have similar or even better mechanical properties than conventional ones regarding sliding resistance. Although the combination of bracket and archwire material is decisive for low sliding resistance values, the selection of the bracket material seems to have a greater influence than the selection of the archwire material or its cross section.Clinical relevanceIt might be possible in future to combine aesthetic and biomechanical requirements for aesthetic brackets by using 3D-printing technology.

Evaluation of torque moment in esthetic brackets from bendable alloy wires.

To examine the torque moment that occurs between esthetic brackets and bendable alloy (stainless steel [SS], titanium-molybdenum [Ti-Mo], and titanium-niobium [Ti-Nb]) wires. This study examined ceramic (CR), zirconium oxide (ZC), polycarbonate (PC), and conventional metallic brackets (MT) (upper, 0.018-inch and 0.022-inch slots) combined with SS, Ti-Mo, and Ti-Nb wires using elastic module ligation. The torque moments delivered by various wire and bracket combinations were measured using a torque gauge apparatus. The wire torque angles at 5-40° were examined. The torque value increased in the order of CR, ZC, MT, and PC brackets for both 0.018-inch and 0.022-inch slots. The fracture points of the CR and ZC brackets combined with SS and Ti-Mo wires were approximately more than 30° and 35°, respectively. No fracture points were detected in the combination of ZC brackets and Ti-Nb wires. The current study identified the material characteristics of CR, ZR, and PC brackets during torque tooth movements. The present results demonstrate a characteristic combined effect between different esthetic brackets and bendable alloy wires.

Effectiveness of low binding frictional materials: Evaluation of the binding frictional resistance of improved superelastic nickel-titanium alloy wires with different bracket combinations

Introduction: This study aimed to evaluate the binding frictional resistance of improved superelastic nickel- titanium alloy wires (ISW) with different bracket combinations and to verify the effectiveness of low binding frictional materials by applying them in orthodontic treatment. Materials and Methods: Straight stainless steel wire (SSW; 0.016 × 0.022-inch) and straight ISW (0.016 × 0.022- inch) were set to each displaced bracket, and the tensile resistance load was measured. The maximum tensile resistance load was statistically compared using the Tukey test. For exemplification, we treated a typical extraction case of Angle Class I crowding malocclusion with lip protrusion using lower binding frictional materials, which were selected based on tensile test results. Results: The SSW and metal bracket combination had the largest maximum tensile resistance load, and the ISW and metal slot-equipped plastic bracket combination had the smallest load (P < 0.01). In a patient treated using lower binding frictional materials, the active treatment period was 9 months. Satisfactory patient results were obtained without using reinforced anchorage. Conclusions: Binding frictional resistance varies, depending on the archwire and bracket combination. In a multibracket appliance, selecting materials with as low a binding frictional resistance as possible may make a more effective treatment.

The effect of heat treatment on sliding mechanics of stainless steel orthodontic wires

Aim: The aim of this study was to evaluate the effect of heat treatment (tempering) on the sliding mechanics of stainless steel Chrome Nickel (CrNi) orthodontic wires. Methods: A universal testing machine EMIC DL 2000 was used at a speed of 10 mm/minute for reading-out the sliding strength and friction between brackets and wires, by simulating the sliding mechanics in a fixed orthodontic appliance. The results were submitted to ANOVA variance test for statistical analysis at the level of 5% (p<0.05). Results: The results indicated that depending on the type of bracket, wire and type of treatment, the groups without heat treatment showed higher mean static friction values, except for groups with CrNi GAC wire and conventional brackets, which showed no significant difference with and without heat treatment; and the group with self-ligated brackets and CrNi GAC wires that showed the lowest mean static friction values with heat treatment. Conclusion: The heat treatment reduced the static friction values on CrNi Morelli wires for any combination of brackets (conventional and self-ligated types) and commercial brands. For the CrNi GAC wires, there was a reduction in friction values only in the combination with In-Ovation R/GAC self-ligated brackets.

The Lie algebra of classical mechanics

Classical mechanical systems are defined by their kinetic and potential energies. They generate a Lie algebra under the canonical Poisson bracket. This Lie algebra, which is usually infinite dimensional, is useful in analyzing the system, as well as in geometric numerical integration. But because the kinetic energy is quadratic in the momenta, the Lie algebra obeys identities beyond those implied by skew symmetry and the Jacobi identity. Some Poisson brackets, or combinations of brackets, are zero for all choices of kinetic and potential energy, regardless of the dimension of the system. Therefore, we study the universal object in this setting, the 'Lie algebra of classical mechanics' modelled on the Lie algebra generated by kinetic and potential energy of a simple mechanical system with respect to the canonical Poisson bracket. We show that it is the direct sum of an abelian algebra \begin{document}$ \mathfrak{X} $\end{document} , spanned by 'modified' potential energies and isomorphic to the free commutative nonassociative algebra with one generator, and an algebra freely generated by the kinetic energy and its Poisson bracket with \begin{document}$ \mathfrak{X} $\end{document} . We calculate the dimensions \begin{document}$ c_n $\end{document} of its homogeneous subspaces and determine the value of its entropy \begin{document}$ \lim_{n\to\infty} c_n^{1/n} $\end{document} . It is \begin{document}$ 1.8249\dots $\end{document} , a fundamental constant associated to classical mechanics. We conjecture that the class of systems with Euclidean kinetic energy metrics is already free, i.e., that the only linear identities satisfied by the Lie brackets of all such systems are those satisfied by the Lie algebra of classical mechanics.

Evaluation of Frictional Characteristics of Nanoparticle Reinforced Arch wires and Brackets

The portion of the applied orthodontic force lost due to resistance to sliding can range from 12-60%. Hence high frictional force can affect the efficiency of treatment, resulting in increased treatment time and compromised treatment results because of loss of anchorage. To develop an ideal orthodontic system, the frictional characteristics between the arch wire-bracket needs to be understood. The purpose of this study was to evaluate the frictional characteristics of the single-walled and multi-walled carbon nanotube coated (SWCNT and MWCNT) arch wire and bracket. Method: 0.019×0.025-in SS arch wire and bracket was coated with SWCNT and MWCNT separately using Chemical Vapour Deposition (CVD) technique. The frictional values between the various combinations of arch wires and brackets were studied using Universal Friction Testing machine. Results: Combination of stainless-steel wire and multi-walled carbon nanotube coated bracket showed the least friction 0.18±0.06. Conclusion: With this different combination of bracket and arch wire we may be able to achieve the optimum levels of orthodontic forces in order to gain normal tooth movement.

Pairwise controllability and motion primitives for micro-rotors in a bounded Stokes flow

Micro-robots that can propel themselves in a low Reynolds number fluid flow by converting their rotational motion into translation have begun attracting much attention due to their ease of fabrication. The dynamics and controllability of the motion of such microswimmers are investigated in this paper. The microswimmers under consideration here are spinning spheres (or rotors) whose dynamics are approximated by rotlets, a singularity solution of the Stokes equations. While singularities of Stokes flows are commonly used as theoretical models for microswimmers and micro-robots, rotlet models of microswimmers have received less attention. While a rotlet alone cannot generate translation, a pair of rotlets can interact and execute net motion. Taking the control inputs to be the strengths of the micro rotors, the positions of a pair of rotors are not controllable in an unbounded planar fluid domain. However, in a bounded domain, which is often the case of practical interest, we show that the positions of the micro rotors are controllable. This is enabled by the interaction of the rotors with the boundaries of the domain. We show how control inputs can be constructed based on combinations of Lie brackets to move the rotors from one point to another in the domain. Another contribution of this paper is the creation of a framework for path planning and control of the motion of Stokes singularities that model the dynamics of microswimmers. This can be extended to microswimmers with other shapes moving in confined fluid domains with complex boundaries.

Effects of orthodontic appliances on the diagnostic quality of magnetic resonance images of the head.

The influence of 4 commonly used fixed orthodontic appliances on artifact formation and diagnostic quality of magnetic resonance (MR) images of the head produced by a 3-T MR scanner was studied. Stainless steel brackets, ceramic brackets, combination of ceramic brackets and steel molar tubes, and multistranded steel mandibular lingual retainers were embedded into custom-made trays for each of 10 adult subjects. Head MR scans of 9 regions were acquired for each subject wearing these trays. SagittalT1-weighted, axial T2-weighted, axial gradient-recalled, axial diffusion-weighted, noncontrast axial MR angiography, and axial fluid-attenuated inversion recovery MR sequences were included. Two neuroradiologists evaluated image distortions and diagnostic qualities of the 1314 acquired images (13860 image slices). The images were affected by appliance, head region, and MR sequence. Stainless steel brackets and molar tubes affected the images the most, and ceramic brackets caused minimal image distortion. Head MR images are differentially affected by orthodontic appliances. The appliance, region imaged, and MR sequence should be considered before imaging patients wearing fixed orthodontic appliances.

Correlation between frictional force and surface roughness of orthodontic archwires.

Lateral force microscopy measures the lateral bending of the cantilever depending on the frictional force acting between the tip and surface. The aim of this study was to investigate and compare the relationship between the surface roughness and frictional resistance of four archwire and bracket combinations consisting of the 0.016-inch NiTi and 0.019 × 0.025-inch stainless steel archwires interacting clinically with two representative self-ligating brackets, active-type Clippy-C(®) ceramic self-ligating brackets, and passive-type Damon(®) stainless steel self-ligating brackets, using the lateral force microscopy technique. A 0.016-inch NiTi archwire interacting with passive-type Damon(®) stainless steel self-ligating brackets showed the smoothest surface roughness and the lowest frictional resistance compared to other combinations. The archwires interacting with passive-type Damon(®) stainless steel self-ligating brackets showed significantly lower surface roughness and frictional resistance than those interacting with active-type Clippy-C(®) ceramic self-ligating brackets. The frictional force in the in vivo archwire and bracket system increased with increasing surface roughness of the archwire. This positive correlation suggests that surface roughness can be used as an evaluating marker for estimating the efficiency of orthodontic treatment, rather than the direct measurement of frictional force.

Comparison of friction among low-friction ligation, conventional ligation and self ligation with conventional stainless steel and esthetic brackets – an in vitro study

BackgroundAmong the numerous factors affecting friction between the bracket-archwire interface, the method of ligation is one of the most important. A number of ways have been proposed to reduce this friction, including self-ligating brackets and more recently Slide™ (Leone SpA, Firenze, Italy) low-friction ligatures. This study aims to compare the frictional forces generated by three different ligation methods; conventional ligation, self ligation and Slide low-friction ligation, using metallic and ceramic brackets. Materials and methodsThree models with 10 aligned brackets (standard, self-ligating and ceramic) were used with conventional and low-friction ligatures to study the frictional resistance generated with 0.016″ Nitinol (NiTi) and 0.019 × 0.025″ Stainless steel (SS) wires. ResultsConventional ligation produced the greatest friction regardless of wire or bracket combination used. With smaller round wires, the self-ligating system exhibited less friction than low-friction ligation and with higher dimension archwires it exhibited greater friction. Slide low-friction ligatures were able to reduce the friction of ceramic brackets in a similar way to stainless steel brackets. ConclusionSlide low-friction ligatures produced a reduction in friction with both metallic and ceramic brackets to a level comparable to that of self-ligating brackets.

Comparison of metal ions release and corrosion potential from different bracket archwire combinations (An in vitro study)

Background: Esthetic treatment is the options of patient seeking orthodontic treatment. Therefore this study was conducted to measure the concentration of Aluminum, Nickel, Chromium and Iron ions released from combination of monocrysralline brackets with different arch wires immersed in artificial saliva at different duration, to evaluate the corrosion point on different parts of the orthodontic appliances before and after immersion in artificial saliva, and to evaluate the corrosion potential of each group of the orthodontic appliances. Material and methods: Eighty orthodontic sets prepared. Each set represents half fixed orthodontic appliance, from the central incisor to the first molar, for the maxillary arch, each set consisted of molar band, five brackets, half arch wire and ligature elastic.These sets are divided into two groups: Group A: with monocrystalline brackets divided into five subgroups (each subgroup has ten sets), but differ in arch wires, as numbered stainless steel, nickel-titanium, thermally activated, coated stainless steel and coated nickel-titanium arch wires respectively. Group B: with stainless steel brackets divided into three subgroups (also each subgroup has ten sets), but differ in arch wires, as numberedstainless steel, nickel-titanium, and thermally activated arch wires respectively. Used optical microscope to check the corrosion points, and used potentiostat techniques to indicate corrosion rate and tendency. Results: The greatest concentration of Aluminum and nickel ions release during the 1st week in group A, then sharply decreased in the 2nd week. The release of chromium ion released increase with increase intervals, while iron ion released decrease with increase time. Both nickel and chromium ions increase with increase intervals in group B,while iron increase to the maximum at 3rd weeks, then began to degrease. Optical microscope displayed pitting, crevices, and intergranular corrosion. Potentiostat techniques indicated that increase corrosion when used stainless steel and coated nickel titanium than others arch wires with group A, while corrosion increase with nickel titanium than stainless steel arch wires with group B. Conclusions: Non-significant difference in the total nickel, chromium and iron release in group B. Aluminum and iron increase in A4 and A5, while nickel and chromium increase in A1 and A2.The total released amounts of metals ions in both groups were less than the amounts of daily intake.

Clinical Applications of CBCT and 3D Digital Technology in Orthodontics

The introduction of cone-beam computed tomography(CBCT) and computer software in orthodontics has allowed orthodontists to provide more accurate diagnosis and treatment. The most common use of CBCT imaging allows orthodontists to visualize the precise position of supernumerary or impacted teeth, especially impacted canines. In doing so, the exact angulation of impaction and proximity of adjacent roots can be evaluated by orthodontists, allowing them to choose vector forces for tooth movement while minimizing root resorption. Even though 2-dimensional panoramic images can be used to view the position of the impacted canines, they have limitations because it is not possible to evaluate the impacted tooth position 3-dimensionally. An accurate knowledge of root position improves the determination of success in orthodontic treatment. Nowadays, considering the fast pace of technological development, a combination of intraoral scanning, digital setups, custommade brackets and wires, and indirect bonding may soon become the orthodontic standard. In this paper, this will be discussed along with the digital models.

Self-ligating brackets in perspective of friction: A Review

No abstract available.

캘리퍼 브레이크 스퀼 소음의 불안정성 해석에 관한 연구

This paper deals with analytical methods for low frequency and high frequency brake squeal noise on brake-rear caliper. In order to improve low frequency and high frequency squeal noise, we take survey caliper bracket shape parameters and housing shape parameters. Besides, using the combination of bracket and housing parameter were surveyed. Thus, using the combination of bracket Alt_05 and housing Alt_45 specifications, instability analysis and brake dynamo test were carried out. Based upon the two models, low and high frequency squeal noise of base model were improved. But, for 6.0 kHz frequency noise, which is not improved, it needs to additionally study on instability analysis and combination of the other brake components.

Comparative Evaluation of Frictional Forces of Conventional and Self-ligating Bracket Systems: An in vitro Study

Introduction: Among the numerous factors affecting friction between the bracket-archwire interface, the method of ligation is one of the most important. A number of ways have been proposed to reduce this friction, including self-ligating brackets and more recently Slide™ (Leone SpA, Firenze, Italy) low-friction ligatures. Aim: This study aims to compare the frictional forces generated by three different ligation methods; conventional ligation, self-ligation and slide low-friction ligation, using metallic and ceramic brackets. Materials and methods: Three models with ten aligned brackets (standard, self-ligating and ceramic) were used with conventional and low-friction ligatures to study the frictional resistance generated with 0.016 nitinol and 0.019 × 0.025 stainless steel wires. Results: Conventional ligation produced the greatest friction regardless of wire or bracket combination used. With smaller round wires, the selfligating system exhibited less friction than low-friction ligation and with higher dimension archwires it exhibited greater friction. Slide low-friction ligatures were able to reduce the friction of ceramic brackets in a similar way to stainless steel brackets.