Carillo, Vitoria Eugenia Bismarck
2004-07-01
The aim of this study in vitro was to compare the share bond strength of the light-cured composite resins Transbond XT (Unitek), with halogen light and argon laser. The Adhesive Remmant Index (ARI) was also investigated. The brackets Dyna lock (3M-UNITEK) were bonded to 75 human premolars, divided into 5 groups (15 each) according to time and the polymerization: Group H20, 15 brackets bonded with halogen light for 20s (10s both sides); Group H40, 15 brackets bonded with halogen light for 40s (20s both sides); Group A40, 15 brackets bonded with argon laser for 40s (20s both sides); Group A20, 15 brackets bonded with argon laser for 20s (10s both sides); Group A10, 15 brackets bonded with argon laser for 10s (5s both sides). The pulpal temperature changes were determined during a polymerization, not exceeding 3,5 deg C. After bonding, the teeth were submitted to a thermo cycled of 700 cycles between 5 deg C and 55 deg C, to simulate the consuming that the light cured composite resin would have in a short space of time. The specimens were then placed in PVC ring and embedded in acrylic resin (Aero-Jet). The tensile bond strength test was performed on an Universal Machine set at a crosshead speed of 1,5 mm/min, and for each rupture we registered a graphic and the best load required in Newtons, was converted to MPa and kgf. The share bond strength showed bigger values for the exposure time of 20 seconds, for the Group bonded for halogen light (H20), 7,45 kgf (7,64 MPa) and for argon laser 7,50 kgf (7,69 MPa); lesser values for the exposure time of 40s for the Group with halogen light (H40), 6,15 kgf (6,30 MPa) and argon laser Group (A40), 6,20 kgf (6,35 MPa) 0; and A10, 4,85 kgf (4,97 MPa). In the ARI Index, only A40 Group showed the 1 Index, with statistical results. In this Group, less than half of the remainder adhesive stayed on the surface of the enamel, conferring specimens failed at the enamel-adhesive interface. The results of the in vitro study demonstrate that
Mashburn, D.; Wald, J. E.; Helmsin, F. K.
1982-01-01
Tiedown bracket secured to concrete slab with lag anchor and lag bolt. A trailer or other heavy equipment can be anchored by tethering it to strapping bolt. When bracket is no longer needed, it can be removed, leaving behind only lag anchor. Bracket is easily installed and removed without damage to concrete slab.
Barletta, Fernando Branco
2007-01-01
Full Text Available O presente trabalho teve como objetivo avaliar a confiabilidade do teste de vitalidade pulpar com o gás refrigerante tetrafluoretano (CS 68 em dentes portadores de brackets ortodônticos. Foram selecionados 37 pacientes de clínica privada, com faixa etária entre 12 e 60 anos de idade. O teste de vitalidade pulpar foi realizado na face palatina ou lingual, na região de terço médio dos dentes, abaixo do cíngulo, nos grupos dentários dos incisivos, caninos e pré-molares superiores e inferiores, totalizando 402 dentes. Quando a resposta de sensibilidade pulpar era negativa ao teste, o mesmo era repetido; confirmando-se o resultado como negativo, realizavase uma tomada radiográfica pela técnica periapical do dente em questão. Os resultados evidenciaram 4 elementos dentários com resposta negativa ao teste de vitalidade pulpar, sendo 3 pré-molares e um incisivo central. A resposta dos demais foi positiva ao teste. Diante dos resultados, verificou-se que a aplicação do teste de vitalidade pulpar pela face palatina em pacientes portadores de brackets ortodônticos constitui-se em uma alternativa segura e confiável.
Nafziger, Julia; Koch, Alexander
It is a puzzle why people often evaluate consequences of choices separately (narrow bracketing) rather than jointly (broad bracketing). We study the hypothesis that a present-biased individual, who faces two tasks, may bracket his goals narrowly for motivational reasons. Goals motivate because th...
Vanvalkenburgh, C.
1985-01-01
Concept allows routing easily changed. No custom hardware required in concept. Instead, standard brackets cut to length and installed at selected locations along cable route. If cable route is changed, brackets simply moved to new locations. Concept for "universal" cable brackets make it easy to route electrical cable around and through virtually any structure.
Bracket for photovoltaic modules
Ciasulli, John; Jones, Jason
2014-06-24
Brackets for photovoltaic ("PV") modules are described. In one embodiment, a saddle bracket has a mounting surface to support one or more PV modules over a tube, a gusset coupled to the mounting surface, and a mounting feature coupled to the gusset to couple to the tube. The gusset can have a first leg and a second leg extending at an angle relative to the mounting surface. Saddle brackets can be coupled to a torque tube at predetermined locations. PV modules can be coupled to the saddle brackets. The mounting feature can be coupled to the first gusset and configured to stand the one or more PV modules off the tube.
Kiyoshige, Kazuki; Yano, Katsuya
2016-01-01
We review recent progress in formulating the worldvolume theory of the M2-branes using the Nambu bracket. Although it is generally agreed that this formulation should be replaced by another using the superconformal Chern-Simons theory, we try to pursue a possible complementary role played by the Nambu bracket. Since the partition function of the superconformal Chern-Simons theory implies a hidden super gauge group, we study the supersymmetric generalization of the Nambu bracket. We construct explicitly the super unitary Nambu algebra.
A. C Dalvi
2010-06-01
Full Text Available Foram avaliadas diferentes formas de glazeamento da superfície de porcelana quanto à resistência ao cisalhamento de bráquetes metálicos colados com diferentes cimentos. Quarenta e dois corpos de prova de metalocerâmica foram confeccionados (2 controles e divididos em quatro grupos de acordo com o tipo de glazeamento, com camada extra de glaze (G ou auto-glazeados (AG, e o cimento utilizado, resina fotopolimerizável (r ou ionômero de vidro resinosos (i, formando os seguintes grupos: Gr, Gi, AGr e AGi com 10 corpos de prova cada grupo. Todas as superfícies dos corpos de prova receberam tratamento com ácido fosfórico 35% por 30 s seguidos de uma camada de silano. Quarenta bráquetes metálicos foram colados. Os corpos de prova foram submetidos a termociclagem e ao teste de resistência ao cisalhamento com uma máquina universal de ensaios mecânicos. Uma amostra de cada grupo após descolagem, remoção da resina e polimento, foi avaliado em microscópio eletrônico de varredura. O índice de fratura coesiva da porcelana foi também avaliado. Os resultados mostram valores acima da média aceitável na literatura para todos os grupos, sendo que o grupo AGr apresentou valor menor (10,38 MPa e estatisticamente significativo em relação aos demais. A análise no microscópio eletrônico de varredura mostrou que as superfícies, após polimento, não readquirem as características de antes da colagem, apesar de se apresentarem aceitáveis clinicamente. Houve fratura da porcelana em todos os grupos. Conclui-se que é possível se conseguir colagem adequada de bráquetes metálicos em superfícies metalocerâmicas auto-glazeadas e com camada extra de glaze, preservando-o, não necessitando reconhecer previamente a forma de glazeamento.Different glazing techniques for porcelain surface were evaluated in terms of shear bond strength of metallic brackets bonded with different cements. Forty-two metal-ceramic samples were made (2 controls and then
Golmankhaneh, Alireza Khalili
2008-01-01
In the present paper fractional Hamilton-Jacobi equation has been derived for dynamical systems involving Caputo derivative. Fractional Poisson-bracket is introduced. Further Hamilton's canonical equations are formulated and quantum wave equation corresponds to the fractional Hamilton-Jacobi equation is suggested. Illustrative examples have been worked out to explain the formalism.
In the extensive literature devoted to the Hamiltonian dynamics of constrained systems, the case when there are no second-class constraints has been thoroughly studied. In particular, the geometrical significance of the objects encountered in generalized Hamiltonian dynamics has been clarified. The foundation of the geometrical interpretation is the symplectic structure generated in the phase space by the Poisson bracket. It is this structure that permits the introduction of Hamiltonian vector fields isomorphic to the differentials of functions in the phase space and to elucidate the structure of the constraint surface. In this work, the possibility of giving a geometrical meaning to Hamiltonian dynamics in the presence of second-class constraints by using the Dirac bracket to define a symplectic structure on the phase space is discussed. 5 refs
Inequalities from Poisson brackets
Alekseev, Anton; Davydenkova, Irina
2015-01-01
We introduce the notion of tropicalization for Poisson structures on $\\mathbb{R}^n$ with coefficients in Laurent polynomials. To such a Poisson structure we associate a polyhedral cone and a constant Poisson bracket on this cone. There is a version of this formalism applicable to $\\mathbb{C}^n$ viewed as a real Poisson manifold. In this case, the tropicalization gives rise to a completely integrable system with action variables taking values in a polyhedral cone and angle variables spanning a...
The recently introduced quantum anti-brackets are further generalized which makes it possible the odd Q operator to be arbitrary one. Obvious formulae for higher quantum anti-brackets of arbitrary orders and their Jacobian generalized identities are presented. The limitation, leading to an ordinary quantum anti-bracket, which is characterized by the same properties as its classical analogue, is considered. The attachments to the Batalin-Vilkovisky-Fradkin quantizations are considered. Some remarks on the corresponding properties and the quantum Sp(2) anti-brackets attachments are presented
Non-equal-time Poisson brackets
Nikolic, H.
1998-01-01
The standard definition of the Poisson brackets is generalized to the non-equal-time Poisson brackets. Their relationship to the equal-time Poisson brackets, as well as to the equal- and non-equal-time commutators, is discussed.
Roberta Buzzoni
2012-08-01
Full Text Available OBJECTIVE: The aim of this study was to assess resistance to sliding of stainless steel passive self-ligating brackets with 0° and 2.5° angulations and to compare them to active self-ligating brackets at zero angulation. The hypothesis to be tested was that passive self-ligating brackets produce lower frictional forces than active self-ligating brackets. METHODS: Twenty five 0.022 x 0.028-in slot maxillary canine brackets were divided into 5 groups of 5 brackets: Damon SL II (Ormco, CA, USA self-ligating bracket and Gemini (3M/Unitek, CA, USA conventional bracket with angulation of 0 and 2.5° and a group of Speed 2 (American Orthodontics, WI, USA active clip self-ligating system with zero angulation. Twenty five segments of stainless steel 0.020-in archwire (TP Orthodontics, IN, USA were tested and each bracket/wire interface was evaluated at 4 successive points during sliding. Overall, 100 frictional values were analyzed by parametric analysis of variance and Bonferroni tests. RESULTS AND CONCLUSION: Frictional tests were performed with an Emic DL 10000 testing machine (Emic, Brazil with a load cell of one kilogram. Passive self-ligating brackets produced lower frictional forces than active self-ligating brackets (p OBJETIVO: avaliar a fricção apresentada por braquetes autoligáveis de aço inoxidável com sistema passivo de tampa deslizante sob angulação de 0 grau e 2,5 graus, e comparar o comportamento desse grupo sob angulação nula com o de um grupo de braquetes autoligáveis com sistema ativo de tampa resiliente. MÉTODOS: foram utilizados 25 braquetes de caninos superiores, divididos em 5 grupos - braquetes autoligáveis passivos Damon SL II sob angulação de 0 grau e de 2,5 graus; braquetes convencionais Gemini amarrados com ligaduras elásticas sob as mesmas angulações; e um grupo formado pelo sistema ativo Time 2, sob angulação nula. A hipótese a ser testada é se artefatos autoligáveis com sistema de tampa passiva s
Evaluation of mechanical properties of esthetic brackets
Umezaki, Eisaku; Komazawa, Daigo; Otsuka, Yuichiro; Suda, Naoto
2015-01-01
Plastic brackets, as well as ceramic brackets, are used in various cases since they have excellent esthetics. However, their mechanical properties remain uncertain. The purpose of this study was to determine how deformation and stress distribution in esthetic brackets differ among materials under the same wire load. Using the digital image correlation method, we discovered the following: (1) the strain of the wings of plastic brackets is within 0.2% and that of ceramic and metal brackets is negligible, (2) polycarbonate brackets having a stainless steel slot show significantly smaller displacement than other plastic brackets, and (3) there is a significant difference between plastic brackets and ceramic and stainless steel brackets in terms of the displacement of the bracket wing. PMID:25755677
Adhesives for orthodontic bracket bonding
Déborah Daniella Diniz Fonseca
2010-04-01
Full Text Available The advent of acid etching, introduced by Buonocore in 1955, brought the possibility of bonding between the bracket base and enamel, contributing to more esthetic and conservative orthodontics. This direct bracket bonding technique has brought benefits such as reduced cost and time in performing the treatment, as well as making it easier to perform oral hygiene. The aim of this study was to conduct a survey of published studies on orthodontic bracket bonding to dental enamel. It was verified that resin composites and glass ionomer are the most studied and researched materials for this purpose. Resin-modified glass ionomer, with its biocompatibility, capacity of releasing fluoride and no need for acid etching on the tooth structure, has become increasingly popular among dentists. However, due to the esthetic and mechanical properties of light polymerizable resin composite, it continues to be one of the adhesives of choice in the bracket bonding technique and its use is widely disseminated.
Evaluation of mechanical properties of esthetic brackets
Matsui, Shigeyuki; Umezaki, Eisaku; Komazawa, Daigo; Otsuka, Yuichiro; Suda, Naoto
2015-01-01
Plastic brackets, as well as ceramic brackets, are used in various cases since they have excellent esthetics. However, their mechanical properties remain uncertain. The purpose of this study was to determine how deformation and stress distribution in esthetic brackets differ among materials under the same wire load. Using the digital image correlation method, we discovered the following: (1) the strain of the wings of plastic brackets is within 0.2% and that of ceramic and metal brackets is n...
Poisson brackets, strings and membranes
We construct Poisson brackets at the boundaries of open strings and membranes with constant background fields which are compatible with their boundary conditions. The boundary conditions are treated as primary constraints which give infinitely many secondary constraints. We show explicitly that we need only two (the primary one and one of the secondary ones) constraints to determine the Poisson brackets of strings. We apply this to membranes by using canonical transformations. (orig.)
A hierarchy of Poisson brackets
Pavelka, Michal; Klika, Vaclav; Esen, Ogul; Grmela, Miroslav
2015-01-01
The vector field generating reversible time evolution of macroscopic systems involves two ingredients: gradient of a potential (a covector) and a degenerate Poisson structure transforming the covector into a vector. The Poisson structure is conveniently expressed in Poisson brackets, its degeneracy in their Casimirs (i.e. potentials whose gradients produce no vector field). In this paper we investigate in detail hierarchies of Poisson brackets, together with their Casimirs, that arise in pass...
Gilberto Vilanova Queiroz
2012-08-01
Full Text Available INTRODUCTION: The purpose of this study was to compare the frictional forces between 0.014-in NiTi wires (Aditek with 4 mm horizontal deflection and brackets with different archwire ligation systems. METHODS: Four types of self-ligating brackets (Damon MX, Easy Clip, Smart Clip and In-Ovation, a triple bracket (Synergy and a twin bracket with 8-shaped ligature (Tecnident were tested. Twin brackets with conventional elastomeric ligatures (Morelli were used as control group. Tests were repeated 10 times for each bracket/archwire combination. Frictional forces were measured in an Instron universal tensile machine at 3 mm/minute speed and a total displacement of 6 mm. Statistical analysis comprised ANOVA and Dunnett's multiple comparison post hoc test. RESULTS: Deflection-induced frictional (DIF forces increased in the following order: Synergy, Damon, 8-shaped Ligature, Easy Clip, In-Ovation, Smart-Clip and conventional ligatures. The differences among groups were significant, with the exception of the 8-shaped ligature groups which was equal to the Damon and Easy Clip groups. CONCLUSIONS: Compared to conventional ligatures, all ligation systems tested reduced frictional forces. However, such reduction varied according to the ligation system employed.OBJETIVO: o objetivo desse trabalho foi comparar as forças de atrito entre fios NiTi 0,014" (Aditek com deformações horizontais de 4mm, e braquetes com diferentes sistemas de ligação dos arcos. MÉTODOS: foram testados 4 tipos de braquetes autoligáveis (Damon MX, Easy Clip, Smart Clip e In-Ovation, um braquete triplo (Synergy e um braquete gêmeo com amarrilho 8 (Tecnident. Como grupo controle, foi utilizado braquete gêmeo com ligadura elástica convencional (Morelli. Foram executadas 10 repetições em cada combinação arco/braquete. As forças de atrito foram medidas em máquina de tração universal Instron, com velocidade de 3mm/minuto e deslocamento total de 6mm. Para análise estat
Wadim Zudilin
2015-01-01
The multiple zeta values (MZVs) possess a rich algebraic structure of algebraic relations, which is conjecturally determined by two different (shuffle and stuffle) products of a certain algebra of noncommutative words. In a recent work, Bachmann constructed a $q$-analogue of the MZVs -- the so-called bi-brackets -- for which the two products are dual to each other, in a very natural way. We overview Bachmann's construction and discuss the radial asymptotics of the bi-brackets, its links to th...
Structural support bracket for gas flow path
None
2016-08-02
A structural support system is provided in a can annular gas turbine engine having an arrangement including a plurality of integrated exit pieces (IEPs) forming an annular chamber for delivering gases from a plurality of combustors to a first row of turbine blades. A bracket structure is connected between an IEP and an inner support structure on the engine. The bracket structure includes an axial bracket member attached to an IEP and extending axially in a forward direction. A transverse bracket member has an end attached to the inner support structure and extends circumferentially to a connection with a forward end of the axial bracket member. The transverse bracket member provides a fixed radial position for the forward end of the axial bracket member and is flexible in the axial direction to permit axial movement of the axial bracket member.
An alternative approach to debonding lingual brackets.
Ali, Hesham; Waring, David T; Malik, Ovais H
2015-01-01
This clinical pearl describes a technique of debonding the lingual brackets with minimum discomfort to the patient. It also reduces the risk of swallowing or aspirating the brackets and decreases the risk of enamel damage. PMID:25881384
Higher Toda brackets and Massey products
Baues, Hans-Joachim; Blanc, David; Gondhali, Shilpa
2015-01-01
We provide a uniform definition of higher order Toda brackets in a general setting, covering the known cases of long Toda brackets for topological spaces and chain complexes and Massey products for differential graded algebras, among others.
Quadratic brackets from symplectic forms
We give a physicist oriented survey of Poisson-Lie symmetries of classical systems. We consider finite-dimensional geometric actions and the chiral WZNW model as examples for the general construction. An essential point is the appearance of quadratic Poisson brackets for group-like variables. It is believed that upon quantization they lead to quadratic exchange algebras. ((orig.))
Murilo Fernando Neuppmann Feres
2009-08-01
Full Text Available OBJETIVOS: comparar os efeitos de diferentes prescrições de braquetes pré-ajustados na movimentação dentária dos dentes anterossuperiores, por meio da utilização do Método de Elementos Finitos (MEF. MÉTODOS: foi utilizado um modelo tridimensional composto por um incisivo central, um incisivo lateral e um canino, todos do hemiarco superior esquerdo. Esses elementos foram submetidos à atuação de vetores de força que simularam a ação dos pré-ajustes de angulação e torque dos braquetes das prescrições de Alexander, Andrews, Capelozza, MBT, Ricketts e Roth. Após a simulação, os dados referentes ao deslocamento espacial dos pontos incisais e apicais foram registrados de forma que o novo posicionamento admitido pelos longos eixos dentários e seus pontos constituintes fossem determinados. RESULTADOS: a maioria das prescrições se comportou similarmente em relação aos parâmetros avaliados. As diferenças significativas encontradas no estudo se referem ao incisivo lateral superior que continha o braquete com a prescrição de Ricketts, que apresentou uma menor inclinação vestibular de seu longo eixo. Além disso, o canino superior da mesma prescrição apresentou uma maior inclinação de seu longo eixo para mesial e uma maior inclinação vestibular de seu longo eixo em relação às outras. A avaliação qualitativa da movimentação do incisivo central superior indicou um maior deslocamento distal dos ápices radiculares para as prescrições cujos autores estipularam maiores valores de angulação (Andrews, Capelozza, Roth e Alexander, e um maior deslocamento vestibular da coroa para as prescrições que estipularam os maiores valores de torque para os incisivos centrais (Ricketts, MBT, Alexander e Roth.AIM: The aim of the present study was to compare the effects of different prescriptions on anterior superior tooth movement simulation through a Finite Element Method (FEM. METHODS: It was utilized a 3D model, which was
Gilberto Vilanova Queiroz; Rafael Yagüe Ballester; João Batista Paiva; José Rino Neto; Giselle Mara Galon
2012-01-01
INTRODUCTION: The purpose of this study was to compare the frictional forces between 0.014-in NiTi wires (Aditek) with 4 mm horizontal deflection and brackets with different archwire ligation systems. METHODS: Four types of self-ligating brackets (Damon MX, Easy Clip, Smart Clip and In-Ovation), a triple bracket (Synergy) and a twin bracket with 8-shaped ligature (Tecnident) were tested. Twin brackets with conventional elastomeric ligatures (Morelli) were used as control group. Tests were rep...
Del Angel Hernandez, Alberto
1999-12-01
criterio para juzgar la confiabilidad de un sistema electrico de potencia, es la frecuencia y duracion de la interrupcion del suministro de energia electrica a los consumidores. Debido a la importancia de mantener la continuidad del servicio de energia electrica, es necesario estudiar los dispositivos de proteccion contra sobretensiones, ya que en condiciones meteorologicas adversas, asi como por condiciones de cambio de configuracion en la red, se pueden presentar sobretensiones que danen a los equipos del sistema electrico de potencia. Los apartarrayos son dispositivos cuya funcion es proteger equipos de un sistema electrico de potencia contra las sobretensiones, por medio de absorcion de energia a traves del sistema de aterrizamiento. En la proteccion de los Sistemas Electricos de Potencia (SEP) contra sobretensiones comunmente se empleaban los apartarrayos de carburo de silicio (SiC) que brindaban un margen de proteccion pequeno. En los ultimos anos se han desarrollado nuevas tecnologias que han revolucionado la coordinacion del aislamiento. Un ejemplo de estas tecnologias es la aplicacion de los apartarrayos de oxidos metalicos (ZnO), los cuales incrementan el margen de proteccion considerablemente. En este trabajo se evaluan las limitaciones y potencialidades reales de los modelos existentes, y el propuesto en este trabajo, de apartarrayos de oxidos metalicos, con la ayuda de las simulaciones digitales en transitorios electromagneticos, cuando los apartarrayos estan sujetos a transitorios por maniobra de interruptores como por descargas atmosfericas. Todas las simulaciones en este trabajo se realizaron con el Programa de Transitorios Electromagneticos (EMTP), que es una herramienta ampliamente usada y recomendada para el analisis de los fenomenos transitorios electromagneticos. El modelado de los apartarrayos de oxidos metalicos en el EMTP es complicado por el comportamiento no lineal de sus elementos y se requiere de una gran precision y cuidado para implementar
Effect of delayed polymerization time and bracket manipulation on orthodontic bracket bonding
Ponikvar, Michael J.
This study examined the effect of bracket manipulation in combination with delayed polymerization times on orthodontic bracket shear bond strength and degree of resin composite conversion. Orthodontics brackets were bonded to extracted third molars in a simulated oral environment after a set period of delayed polymerization time and bracket manipulation. After curing the bracket adhesive, each bracket underwent shear bond strength testing followed by micro-Raman spectroscopy analysis to measure the degree of conversion of the resin composite. Results demonstrated the shear bond strength and the degree of conversion of ceramic brackets did not vary over time. However, with stainless steel brackets there was a significant effect (p ≤ 0.05) of delay time on shear bond strength between the 0.5 min and 10 min bracket groups. In addition, stainless steel brackets showed significant differences related to degree of conversion over time between the 0.5 min and 5 min groups, in addition to the 0.5 min and 10 min groups. This investigation suggests that delaying bracket adhesive polymerization up to a period of 10 min then adjusting the orthodontic bracket may increase both shear bond strength and degree of conversion of stainless steel brackets while having no effect on ceramic brackets.
A hierarchy of Poisson brackets
Pavelka, Michal; Esen, Ogul; Grmela, Miroslav
2015-01-01
The vector field generating reversible time evolution of macroscopic systems involves two ingredients: gradient of a potential (a covector) and a degenerate Poisson structure transforming the covector into a vector. The Poisson structure is conveniently expressed in Poisson brackets, its degeneracy in their Casimirs (i.e. potentials whose gradients produce no vector field). In this paper we investigate in detail hierarchies of Poisson brackets, together with their Casimirs, that arise in passages from more to less detailed (i.e. more macroscopic) descriptions. In particular, we investigate the passage from mechanics of particles (in its Liouville representation) to the reversible kinetic theory and the passage from the reversible kinetic theory to the reversible fluid mechanics. From the physical point of view, the investigation includes binary mixtures and two-point formulations suitable for describing turbulent flows. From the mathematical point of view, we reveal the Lie algebra structure involved in the p...
Shingle assembly with support bracket
Almy, Charles
2007-01-02
A shingle system, mountable to a support surface, includes overlapping shingle assemblies. Each shingle assembly comprises a support bracket, having upper and lower ends, secured to a shingle body. The upper end has an upper support portion, extending away from the shingle body, and an upper support-surface-engaging part, engageable with a support surface so that the upper edge of the shingle body is positionable at a first distance from the support surface to create a first gap therebetween. The lower end has a lower support portion extending away from the lower surface. The support brackets create: (1) a second gap between shingle bodies of the first and second shingle assemblies, and (2) an open region beneath the first shingle assembly fluidly coupling the first and second gaps.
Quantum Enhancements and Biquandle Brackets
Nelson, Sam; Orrison, Michael E.; Rivera, Veronica
2015-01-01
We introduce a new class of quantum enhancements we call biquandle brackets, which are customized skein invariants for biquandle colored links.Quantum enhancements of biquandle counting invariants form a class of knot and link invariants that includes biquandle cocycle invariants and skein invariants such as the HOMFLY-PT polynomial as special cases, providing an explicit unification of these apparently unrelated types of invariants. We provide examples demonstrating that the new invariants a...
Exterior differentials in superspace and Poisson brackets
It is shown that two definitions for an exterior differential in superspace, giving the same exterior calculus, yet lead to different results when applied to the Poisson bracket. A prescription for the transition with the help of these exterior differentials from the given Poisson bracket of definite Grassmann parity to another bracket is introduced. It is also indicated that the resulting bracket leads to generalization of the Schouten-Nijenhuis bracket for the cases of superspace and brackets of diverse Grassmann parities. It is shown that in the case of the Grassmann-odd exterior differential the resulting bracket is the bracket given on exterior forms. The above-mentioned transition with the use of the odd exterior differential applied to the linear even/odd Poisson brackets, that correspond to semi-simple Lie groups, results, respectively, in also linear odd/even brackets which are naturally connected with the Lie superalgebra. The latter contains the BRST and anti-BRST charges and can be used for calculation of the BRST operator cogomology. (author)
Roberta Buzzoni; Elias, Carlos N.; Daniel J. Fernandes; José Augusto M. Miguel
2012-01-01
OBJECTIVE: The aim of this study was to assess resistance to sliding of stainless steel passive self-ligating brackets with 0° and 2.5° angulations and to compare them to active self-ligating brackets at zero angulation. The hypothesis to be tested was that passive self-ligating brackets produce lower frictional forces than active self-ligating brackets. METHODS: Twenty five 0.022 x 0.028-in slot maxillary canine brackets were divided into 5 groups of 5 brackets: Damon SL II (Ormco, CA, USA) ...
Degenerate odd Poisson bracket on Grassmann variables
A linear degenerate odd Poisson bracket (antibracket) realized solely on Grassmann variables is proposed. It is revealed that this bracket has at once three Grassmann-odd nilpotent Δ-like differential operators of the first, second, and third orders with respect to the Grassmann derivatives. It is shown that these Δ-like operators together with the Grassmann-odd nilpotent Casimir function of this bracket form a finite-dimensional Lie superalgebra
On covariant Poisson brackets in field theory
Sharapov, Alexey A.
2014-01-01
A general approach is proposed to constructing covariant Poisson brackets in the space of histories of a classical field-theoretical model. The approach is based on the concept of Lagrange anchor, which was originally developed as a tool for path-integral quantization of Lagrangian and non-Lagrangian dynamics. The proposed covariant Poisson brackets generalize the Peierls' bracket construction known in the Lagrangian field theory.
Uc Way, Manuel Eugenio
1998-02-01
obtained. This value is small when it is compared with the effect that introduces the deposition of slag in these banks of tubes, that is in the order of 50 to 250 Celsuis degrees approximately, for this interval of thermal flows. [Espanol] Debido a la corrosion por alta temperatura se tiene un serio problema por indisponibilidad y eficiencia de los generadores de vapor en las centrales termoelectricas. Una de las partes mas afectadas por este fenomeno son los bancos de tubos de los sobrecalentadores. Con el objeto de disminuir dicho problema se pretende aplicar a los tubos antes mencionados un recubrimiento metalico a base de niquel y cromo (80Ni20Cr), la deposicion del recubrimiento se hace por el metodo de termorrociado de polvos por flama. El espesor del recubrimiento una vez que ha sido depositado es del orden de 500mm, es indudable que el flujo termico entre los gases de combustion y el fluido conducido en los tubos se ve afectado. Por esto es importante conocer la conductividad termica del recubrimiento a fin de evaluar el impacto que se tiene en el funcionamiento del generador de vapor. Esta necesidad es la que da lugar al presente proyecto de tesis, en el cual se disena una tecnica que permite medir la conductividad termica del recubrimiento. La experimentacion se lleva a cabo tomando como punto de partida la norma E1225-87 de la ASTM y se adecua a las caracteristicas del material a probar. Se diseno una probeta de acero inoxidable 316 para medir el flujo termico que atraviesa el recubrimiento. Primero se caracterizo la instalacion experimental a fin de determinar su confiabilidad. Posteriormente se realizo la experimentacion encontrandose una conductividad termica promedio de 12.09{+-}0.72 W/m K en el intervalo de temperatura de 110-180 grados Celsius. Este valor es 12.3% inferior al correspondiente a un metal solido de la misma composicion. Si consideramos que en los bancos de alta temperatura de los generadores de vapor el flujo termico se encuentra en el
Ho, Pei-Ming
2016-01-01
Nambu proposed an extension of dynamical system through the introduction of a new bracket (Nambu bracket) in 1973. This article is a short review of the developments after his paper. Some emphasis are put on a viewpoint that the Nambu bracket naturally describes extended objects which appear in M-theory and the fluid dynamics. The latter part of the paper is devoted to a review of the studies on the Nambu bracket (Lie 3-algebra) in Bagger-Lambert-Gustavsson theory of multiple M2-branes. This paper is a contribution to the proceedings of Nambu memorial symposium (Osaka City University, September 29, 2015).
Delayed bracket placement in orthodontic treatment
Chandra Wigati
2008-12-01
Full Text Available Background: Beside bracket position, the timing of bracket placement is one of the most essential in orthodontic treatment with fixed appliances. Even it seems simple the timing of bracket placement can be crucial and significantly influence the result of orthodontic treatment. However it is often found brackets are placed without complete understanding of its purpose and effects, which could be useless and even detrimental for the case. Purpose: The aim of this case report is to show that the timing of bracket placement could be different depending on the cases. Case: Five different cases are presented here with different timing of bracket placement. Case management: On these cases, brackets were placed on the upper arch first, on the lower arch first, or even only on some teeth first. Good and efficient orthodontic treatment results were achieved. Conclusion: For every orthodontic case, from the very beginning of treatment, bracket should be placed with the end result in mind. If brackets are correctly placed at a correct time, better treatment result could be achieved without unnecessary round tripping tooth movement.
Wadim Zudilin
2015-03-01
Full Text Available The multiple zeta values (MZVs possess a rich algebraic structure of algebraic relations, which is conjecturally determined by two different (shuffle and stuffle products of a certain algebra of noncommutative words. In a recent work, Bachmann constructed a q-analogue of the MZVs—the so-called bi-brackets—for which the two products are dual to each other, in a very natural way. We overview Bachmann’s construction and discuss the radial asymptotics of the bi-brackets, its links to the MZVs, and related linear (independence questions of the q-analogue.
A scanning electron microscopic investigation of ceramic orthodontic brackets
Ceramic brackets were introduced to overcome the esthetic disadvantages of stainless steel brackets. The clinical impression of these brackets is very favorable. However, the sliding mechanics used in the Straightwire (A Company, San Diego, CA, USA) system appear to produce slower tooth movements with ceramic compared to stainless steel brackets. To determine whether this was due to any obvious mechanical problem in the bracket slot, Transcend (Unitek Corporation/3M, Monrovia, CA, USA) ceramic brackets were examined by a scanning electron microscope and compared to stainless steel brackets.Consistently, large surface defects were found in the ceramic bracket slots that were not present in the metal bracket slots. These irregularities could obviously hinder the sliding mechanics of the bracket slot-archwire system and create a greater demand on anchorage. Conversely, the fitting surface of the Transcend ceramic bracket showed extremely smooth surface characteristics, and it would seem advisable for the manufacturers to incorporate this surface within the bracket slot. (author)
Roberta Ferreira Pimentel
2013-02-01
Full Text Available OBJECTIVE: To evaluate and compare "in vitro" the maximum friction force generated by three types of esthetic brackets, two types of polycrystalline conventional ceramic brackets (20/40 and InVu and one type of sapphire monocrystalline bracket (Radiance in dry and artificial saliva wet settings. Also, to evaluate the influence exerted by artificial saliva on the friction forces of those brackets. METHODS: Tests were performed in dry and artificial saliva wet setting (Oral Balance by using an EMIC DL 10000 testing machine, simulating a 2 mm slide of 0.019 x 0.025-in rectangular stainless steel wires over the pre-angulated and pre-torqued (right superior canine, Roth prescription, slot 0.022 x 0.030-in brackets (n = 18 for each bracket. In order to compare groups in dry and wet settings, the ANOVA was used. For comparisons related to the dry versus wet setting, the student t test was used for each group. RESULTS: The results showed that in the absence of saliva the Radiance monocrystalline brackets showed the highest friction coefficients, followed by the 20/40 and the InVu polycrystalline brackets. In tests with artificial saliva, the Radiance and the 20/40 brackets had statistically similar friction coefficients and both were greater than that presented by the InVu brackets. The artificial saliva did not change the maximum friction force of the Radiance brackets, but, for the others (20/40 and InVu, an increase of friction was observed in its presence. CONCLUSION: The InVu brackets showed, in the absence and in the presence of saliva, the lowest friction coefficient.OBJETIVO: avaliar e comparar in vitro as cargas máximas de atrito geradas por três tipos de braquetes estéticos, sendo dois deles cerâmicos policristalinos convencionais (20/40 e InVu e um monocristalino de safira (Radiance, em ambientes seco e umedecido por saliva artificial. Também avaliar a influência exercida pela saliva artificial sobre as cargas de atrito dos referidos
Lee, Souk Min
2015-01-01
Objective This study aimed to compare the frictional force (FR) in self-ligating brackets among different bracket-archwire angles, bracket materials, and archwire types. Methods Passive and active metal self-ligating brackets and active ceramic self-ligating brackets were included as experimental groups, while conventional twin metal brackets served as a control group. All brackets were maxillary premolar brackets with 0.022 inch [in] slots and a -7° torque. The orthodontic wires used included 0.018 round and 0.019 × 0.025 in rectangular stainless steel wires. The FR was measured at 0°, 5°, and 10° angulations as the wire was drawn through the bracket slots after attaching brackets from each group to the universal testing machine. Static and kinetic FRs were also measured. Results The passive self-ligating brackets generated a lower FR than all the other brackets. Static and kinetic FRs generally increased with an increase in the bracket-archwire angulation, and the rectangular wire caused significantly higher static and kinetic FRs than the round wire (p < 0.001). The metal passive self-ligating brackets exhibited the lowest static FR at the 0° angulation and a lower increase in static and kinetic FRs with an increase in bracket-archwire angulation than the other brackets, while the conventional twin brackets showed a greater increase than all three experimental brackets. Conclusions The passive self-ligating brackets showed the lowest FR in this study. Self-ligating brackets can generate varying FRs in vitro according to the wire size, surface characteristics, and bracket-archwire angulation. PMID:25667913
Clinical Survival of Rebonded Brackets with Different ARI Scores
Mohammad Hossein Ahangar Atashi; Setareh Khosravib; Seyyed Mahdi Vahid Pakdel
2016-01-01
Introduction: Bracket debonding is one of the most common events in orthodontics. The aim of the present study was to quantitatively compare clinical survival of rebonded brackets with different ARI scores with new brackets rebonding. Materials and Methods: The subjects in the present study consisted of 74 patients with 76 debonded brackets on maxillary first and second premolars. After refreshing the bracket base of the debonded brackets, they were assigned in two groups: group A with 27 bra...
Tool Releases Optical Elements From Spring Brackets
Gum, J. S.
1984-01-01
Threaded hooks retract bracket arms holding element. Tool uses three hooks with threaded shanks mounted in ring-shaped holder to pull on tabs to release optical element. One person can easily insert or remove optical element (such as prism or lens) from spring holder or bracket with minimal risk of damage.
Courant-like brackets and loop spaces
Ekstrand, Joel; Zabzine, Maxim
2011-01-01
We study the algebra of local functionals equipped with a Poisson bracket. We discuss the underlying algebraic structures related to a version of the Courant-Dorfman algebra. As a main illustration, we consider the functionals over the cotangent bundle of the superloop space over a smooth manifold. We present a number of examples of the Courant-like brackets arising from this analysis.
Courant-like brackets and loop spaces
Ekstrand, Joel
2009-01-01
We study the algebra of local functionals equipped with a Poisson bracket. We discuss the underlying algebraic structures related to a version of the Courant-Dorfman algebra. As a main illustration, we consider the functionals over the cotangent bundle of the superloop space over a smooth manifold. We present a number of examples of the Courant-like brackets arising from this analysis.
Hom-Big Brackets: Theory and Applications
Cai, Liqiang; Sheng, Yunhe
2015-01-01
In this paper, we introduce the notion of hom-big brackets, which is a generalization of Kosmann-Schwarzbach's big brackets. We show that it gives rise to a graded hom-Lie algebra. Thus, it is a useful tool to study hom-structures. In particular, we use it to describe hom-Lie bialgebras and hom-Nijenhuis operators.
Clinical Survival of Rebonded Brackets with Different ARI Scores
Mohammad Hossein Ahangar Atashi
2016-01-01
Full Text Available Introduction: Bracket debonding is one of the most common events in orthodontics. The aim of the present study was to quantitatively compare clinical survival of rebonded brackets with different ARI scores with new brackets rebonding. Materials and Methods: The subjects in the present study consisted of 74 patients with 76 debonded brackets on maxillary first and second premolars. After refreshing the bracket base of the debonded brackets, they were assigned in two groups: group A with 27 brackets of ARI≥4 and group B with 28 brackets of ARI≤2. In 21 cases, new brackets were used (group C. The frequency of the debonding in each rebonded group during treatment was calculated in intervals of 6,12,18 mounths after onset of bracket rebonding . Chi-squared test was used to compare the frequency of debonded brackets. Results: The frequency of debonded brackets was significantly higher in group B (ARI≤2 than those of groups A (ARI≥4 and C (new brackets. The number of debonded brackets were not significantly different between groups A (ARI≥4 and C (new brackets. Conclusion: Rebonding strength of debonded brackets in those that the failure is presented between adhesive and enamel (ARI≥4 could be clinically acceptable with no need to use new brackets. Key words: dental bonding; orthodontic brackets; prevalence
Maria Regina Guerra MONTEIRO
2014-06-01
Full Text Available Objective: To compare the influence of archwire material (NiTi, beta-Ti and stainless steel and brackets design (self-ligating and conventional on the frictional force resistance. Material and Methods: Two types of brackets (self-ligating brackets - Smartclip, 3M/Unitek - and conventional brackets - Gemini, 3M/Unitek with three (0, 5, and 10 degrees slot angulation attached with elastomeric ligatures (TP Orthodontics were tested. All brackets were tested with archwire 0.019"x0.025" nickel-titanium, beta-titanium, and stainless steel (Unitek/3M. The mechanical testing was performed with a universal testing machine eMIC DL 10000 (eMIC Co, Brazil. The wires were pulled from the bracket slots at a cross-head speed of 3 mm/min until 2 mm displacement. Results: Self-ligating brackets produced significantly lower friction values compared with those of conventional brackets. Frictional force resistance values were directly proportional to the increase in the bracket/ wire angulation. With regard to conventional brackets, stainless steel wires had the lowest friction force values, followed by nickel-titanium and beta-titanium ones. With regard to self-ligating brackets, the nickel-titanium wires had the lowest friction values, significantly lower than those of other materials. Conclusion: even at different angulations, the self-ligating brackets showed significantly lower friction force values than the conventional brackets. Combined with nickel-titanium wires, the self-ligating brackets exhibit much lower friction, possibly due to the contact between nickel-titanium clips and wires of the same material.
MONTEIRO, Maria Regina Guerra; da SILVA, Licinio Esmeraldo; ELIAS, Carlos Nelson; VILELLA, Oswaldo de Vasconcellos
2014-01-01
Objective To compare the influence of archwire material (NiTi, beta-Ti and stainless steel) and brackets design (self-ligating and conventional) on the frictional force resistance. Material and Methods Two types of brackets (self-ligating brackets - Smartclip, 3M/Unitek - and conventional brackets - Gemini, 3M/Unitek) with three (0, 5, and 10 degrees) slot angulation attached with elastomeric ligatures (TP Orthodontics) were tested. All brackets were tested with archwire 0.019"x0.025" nickel-titanium, beta-titanium, and stainless steel (Unitek/3M). The mechanical testing was performed with a universal testing machine eMIC DL 10000 (eMIC Co, Brazil). The wires were pulled from the bracket slots at a cross-head speed of 3 mm/min until 2 mm displacement. Results Self-ligating brackets produced significantly lower friction values compared with those of conventional brackets. Frictional force resistance values were directly proportional to the increase in the bracket/ wire angulation. With regard to conventional brackets, stainless steel wires had the lowest friction force values, followed by nickel-titanium and beta-titanium ones. With regard to self-ligating brackets, the nickel-titanium wires had the lowest friction values, significantly lower than those of other materials. Conclusion even at different angulations, the self-ligating brackets showed significantly lower friction force values than the conventional brackets. Combined with nickel-titanium wires, the self-ligating brackets exhibit much lower friction, possibly due to the contact between nickel-titanium clips and wires of the same material. PMID:25025564
Mohammad Karim Soltani
2015-03-01
Full Text Available Statement of the Problem: Frictional forces are considered as important counter-force to orthodontic tooth movement. It is claimed that self-ligating brackets reduce the frictional forces. Purpose: The aim of this study was to compare the resistance to sliding in metallic and clear Damon brackets with the conventional brackets in a wet condition. Materials and Method: The samples included 4 types of brackets; metallic and clear Damon brackets and metallic and clear conventional brackets (10 brackets in each group. In this study, stainless steel wires sized 0.019×0.025 were em-ployed and the operator’s saliva was used to simulate the conditions of oral cavity. The tidy-modified design was used for simulation of sliding movement. The resistance to sliding and static frictional forces was measured by employing Testometric machine and load cell. Results: The mean (±SD of resistance to sliding was 194.88 (±26.65 and 226.62 (±39.9 g in the esthetic and metallic Damon brackets, while these values were 187.81(±27.84 and 191.17(±66.68 g for the clear and metallic conventional brackets, respectively. Static frictional forces were 206.4(±42.45 and 210.38(±15.89 g in the esthetic and metallic Damon brackets and 220.63(±49.29 and 215.13(±62.38 g in the clear and metallic conventional brackets. According to two-way ANOVA, no significant difference was observed between the two bracket materials (clear and metal and the two types of bracket (self-ligating versus conventional regarding resistance to sliding (p= 0.17 and p= 0.23, respectively and static frictional forces (p= 0.55 and p= 0.96, respectively. Conclusion: Neither the type of bracket materials nor their type of ligation made difference in resistance to sliding and static friction.
Bond strength of thermally recycled metal brackets.
Wheeler, J J; Ackerman, R J
1983-03-01
Bracket recycling has emerged concurrently with the practice of direct bonding. This study was undertaken to determine the effect of recycling on the retention of mesh-backed stainless steel brackets. Mesh strand diameter was measured on forty new brackets. These brackets were bonded to recently extracted human premolar teeth, and the tensile force required to fracture each bond was recorded. The brackets were then reconditioned by a thermal process. The mesh strand size was remeasured and the tensile test was repeated. It was found that (1) mesh strand diameter decreased 7 percent during the reconditioning process (93.89 microns +/- 3.17 S.D. compared to 87.07 microns +/- 4.76 S.D., z = 17.62, P less than 1 X 10(-5) ), (2) new bracket bonds were 6 percent stronger than recycled bracket bonds (43.88 pounds +/- 7.98 S.D. bond strength), and (3) reduction in mesh strand diameter during the reconditioning process did not correlate with changes in bond strength between initial and recycled bonding (Pearson r = 0.038). PMID:6338725
Are torque values of preadjusted brackets precise?
Alessandra Motta Streva
2011-08-01
Full Text Available OBJECTIVE: The aim of the present study was to verify the torque precision of metallic brackets with MBT prescription using the canine brackets as the representative sample of six commercial brands. MATERIAL AND METHODS: Twenty maxillary and 20 mandibular canine brackets of one of the following commercial brands were selected: 3M Unitek, Abzil, American Orthodontics, TP Orthodontics, Morelli and Ortho Organizers. The torque angle, established by reference points and lines, was measured by an operator using an optical microscope coupled to a computer. The values were compared to those established by the MBT prescription. RESULTS: The results showed that for the maxillary canine brackets, only the Morelli torque (-3.33º presented statistically significant difference from the proposed values (-7º. For the mandibular canines, American Orthodontics (-6.34º and Ortho Organizers (-6.25º presented statistically significant differences from the standards (-6º. Comparing the brands, Morelli presented statistically significant differences in comparison with all the other brands for maxillary canine brackets. For the mandibular canine brackets, there was no statistically significant difference between the brands. CONCLUSIONS: There are significant variations in torque values of some of the brackets assessed, which would clinically compromise the buccolingual positioning of the tooth at the end of orthodontic treatment.
Heat Exchanger Support Bracket Design Calculations
This engineering note documents the design of the heat exchanger support brackets. The heat exchanger is roughly 40 feet long, 22 inches in diameter and weighs 6750 pounds. It will be mounted on two identical support brackets that are anchored to a concrete wall. The design calculations were done for one bracket supporting the full weight of the heat exchanger, rounded up to 6800 pounds. The design follows the American Institute of Steel Construction (AISC) Manual of steel construction, Eighth edition. All calculated stresses and loads on welds were below allowables.
Longitudinal tibial epiphyseal bracket in Nievergelt syndrome
A patient is described with lower extremity mesomelic dwarfism associated with bilateral congenital elbow, hip, and knee dislocations. Rhomboid-shaped tibiae and delayed ossification of the primary fibular ossification centers were demonstrated at birth. Plain films and magnetic resonance imaging revealed that the tibial deformities were due to the presence of longitudinal epiphyseal brackets. These brackets were observed at surgery and confirmed histologically. Recognition of the longitudinal epiphyseal bracket and its relationship to the tibial deformities seen in this patient with Nievergelt syndrome is important for planning surgical treatment. (orig.)
Ariana Pulido Guerrero
2010-03-01
Full Text Available The aim of this study was to evaluate, in vitro, frictional forces produced by ceramic brackets and arch wires of different alloys. Frictional tests were performed on three ceramic brackets: monocrystalline (Inspire ICE, polycrystalline (InVu, polycrystalline with metal slot (Clarity, and one stainless steel bracket (Dyna-Lock. Thirty brackets of each were tested, all with .022" slots, in combination with stainless steel and nickel-titanium wires .019" × .025", at 0° and 10° angulation, in artificial saliva. Arch wires were pulled through the slots at a crosshead speed of 10 mm/min. There were statistically significant differences between the groups of brackets and wires studied (p < .05. The polycrystalline brackets with metal slots had values similar to those of conventional polycrystalline brackets, and the monocrystalline brackets had the highest frictional forces. The nickel-titanium wires produced the lowest friction. The addition of metal slots in the polycrystalline brackets did not significantly decrease frictional values. Nickel-titanium wires produced lower friction than those of stainless steel.
Linear odd Poisson bracket on Grassmann variables
A linear odd Poisson bracket (antibracket) realized solely in terms of Grassmann variables is suggested. It is revealed that the bracket, which corresponds to a semi-simple Lie group, has at once three Grassmann-odd nilpotent Δ-like differential operators of the first, the second and the third orders with respect to Grassmann derivatives, in contrast with the canonical odd Poisson bracket having the only Grassmann-odd nilpotent differential Δ-operator of the second order. It is shown that these Δ-like operators together with a Grassmann-odd nilpotent Casimir function of this bracket form a finite-dimensional Lie superalgebra. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)
[Brackets and friction in orthodontics: experimental study].
Ben Rejeb Jdir, Saloua; Tobji, Samir; Turki, Wiem; Dallel, Ines; Khedher, Nedra; Ben Amor, Adel
2015-09-01
Many authors have been involved in developing brackets in order to improve the quality, stability, speed and efficiency of orthodontic treatment. In order to reduce friction between bracket and archwire, new therapeutic approaches have been devised based on novel technologies. Among these innovative techniques, self-ligating brackets are increasingly popular. SLBs can be classified into several categories according to their mode of action and their materials. We performed an experimental study to compare the friction forces generated during the sliding of orthodontic archwires made from various alloys through conventional and self-ligating brackets. Results show the favorable influence of SLBs, compared to conventional systems using elastomeric or metal ligatures, on the level of friction, particularly when shape-memory Ni-Ti archwires are used. PMID:26370596
Bihamiltonian cohomology of KdV brackets
Carlet, Guido; Posthuma, Hessel; Shadrin, Sergey
2014-01-01
Using spectral sequences techniques we compute the bihamiltonian cohomology groups of the pencil of Poisson brackets of dispersionless KdV hierarchy. In particular this proves a conjecture of Liu and Zhang about the vanishing of such cohomology groups.
Bihamiltonian Cohomology of KdV Brackets
Carlet, Guido; Posthuma, Hessel; Shadrin, Sergey
2016-02-01
Using spectral sequences techniques we compute the bihamiltonian cohomology groups of the pencil of Poisson brackets of dispersionless KdV hierarchy. In particular, this proves a conjecture of Liu and Zhang about the vanishing of such cohomology groups.
Frictional Resistance of Three Types of Ceramic Brackets
Williams, Claire L; Khaled Khalaf
2014-01-01
ABSTRACT Objectives To investigate the static frictional resistance at the bracket/archwire interface in two recently introduced bracket systems and compare them to conventional ceramic and conventional metal bracket systems. Three variables were considered including the bracket system, archwire type and archwire angulation. Material and Methods Four bracket systems were tested in vitro: Self ligating ceramic, ceramic with metal slot and module, conventional ceramic with module and convention...
Goal Bracketing and Self-Control
Alice Hsiaw
2015-01-01
This paper studies the role of goal bracketing to attenuate time inconsistency. When setting non-binding goals in multi-stage project, an agent must also decide how and when to evaluate himself against such goals. In particular, he can bracket broadly by setting an aggregate goal for the entire project, or narrowly by setting incremental goals for individual stages. In the presence of loss aversion and uncertainty over outcomes, this decision involves a trade-off between motivation and compar...
On the quantization of Nambu brackets
We present several non-trivial examples of the three-dimensional quantum Nambu bracket which involve square matrices or three-index objects. Our examples satisfy two fundamental properties of the classical Nambu bracket: they are skew-symmetric and they obey the Fundamental Identity. We contrast our approach to the existing literature on the quantum deformations of Nambu mechanics. We also discuss possible applications of our results in M-theory. (author)
Analysis of mesiodistal angulations of preadjusted brackets
Marcos Rogério de MENDONÇA; Verri, Ana Caroline Gonçales; Aubrey Fernando FABRE; Cuoghi, Osmar Aparecido
2014-01-01
Manufacturers offer various prescriptions of preadjusted brackets for use in the “straight-wire” orthodontic technique. However, the need to incorporate bends in the rectangular wires during orthodontic finishing has led to concerns regarding the type of prescription chosen and the credibility of information provided by the manufacturer. The aim of this study was to compare the slot angulations of Roth prescription preadjusted metallic brackets for the maxillary left central incisor and maxil...
Analysis of mesiodistal angulations of preadjusted brackets
Marcos Rogério de MENDONÇA
2014-08-01
Full Text Available Manufacturers offer various prescriptions of preadjusted brackets for use in the “straight-wire” orthodontic technique. However, the need to incorporate bends in the rectangular wires during orthodontic finishing has led to concerns regarding the type of prescription chosen and the credibility of information provided by the manufacturer. The aim of this study was to compare the slot angulations of Roth prescription preadjusted metallic brackets for the maxillary left central incisor and maxillary left canine. For each tooth type, 10 brackets of three commercial brands (GAC, Forestadent and Morelli were selected. Two individual metal matrices for brackets and tooth positioning were made for each group of teeth. Captured images were obtained by standardized ortho-radial photography with a digital camera. Images were exported and analyzed with the Image J software package. One-way ANOVA and Tukey statistical analyses were performed at the 5% significance level. For brackets of the maxillary left central incisor, differences in mean angulation were observed between the Morelli and GAC groups (p < 0.01 and between the Forestadent and GAC groups (p < 0.01. For brackets of the maxillary left canine, differences in mean angulation were found between the Morelli and GAC groups (p < 0.01 and between the Morelli and Forestadent groups (p < 0.05. In conclusion, despite their same prescription name, the different brands exhibited significantly different angulation measurements.
Vanessa Nínia Correia Lima
2010-04-01
Full Text Available OBJETIVO: a finalidade deste estudo in vitro foi avaliar e comparar a resistência friccional em braquetes de aço inoxidável e de policarbonato compósito amarrados com fio metálico e elastômeros. MÉTODOS: foram utilizados quatro braquetes de aço inoxidável e quatro de policarbonato compósito (PC para pré-molares levados à máquina universal de ensaio mecânico para a tração de um segmento de fio de aço inoxidável 0,019" x 0,025" na velocidade de 0,5mm/min, com 8mm de deslocamento total. A forma de amarração variou entre as seguintes possibilidades: amarração metálica com pinça de Steiner, metálica com pinça Mathieu, elastômero da marca Morelli e elastômero da marca TP Orthodontics. RESULTADOS E CONCLUSÕES: os módulos elastoméricos geraram mais atrito do que os metálicos e a amarração com pinça Mathieu provocou menor atrito quando comparada a todas as situações avaliadas. Os braquetes de PC geraram menor atrito do que os metálicos, porém, na escolha do material a ser utilizado na clínica, outras variáveis - tais como a resistência ao cisalhamento e à fratura, a estabilidade de cor e a aderência por microrganismos - devem ser consideradas.OBJECTIVE: This in vitro study evaluated and compared the frictional resistance of stainless steel and polycarbonate (PC composite brackets tied with metal wire and elastomeric ligation. METHODS: Four stainless steel and four polycarbonate composite brackets for premolars were placed in a universal testing machine for the traction of a piece of 0.019 x 0.025-in wire at 0.5 mm/min and total displacement of 8 mm. Ligations were performed according to the following alternatives: metal ligation with Steiner tying pliers; metal ligation using Mathieu tying pliers; Morelli™ elastomeric ligation; and TP Orthodontics™ elastomeric ligation. RESULTS AND CONCLUSIONS: Elastomeric modules generated more friction than the metal ligations, and the ligation with the Mathieu tying
Cabral, Stenio Cavalier; Oliveira, Hellen Cristine Prata de; Filgueira, Marcello, E-mail: stenio@uenf.b [Universidade Estadual do Norte Fluminense (PPGECM/CCT/UENF), Campos dos Goytacazes, RJ (Brazil). Centro de Ciencias e Tecnologia. Programa de Pos Graduacao em Engenharia e Ciencia dos Materiais
2010-07-01
Iron is a strong catalyst of graphitization of diamonds. This graphitization occurs mainly during the processing of composites - conventional sintering or hot pressing, and during cutting operations. Aiming to avoid or minimize this deleterious effect, there is increasing use of diamond coated with metallic materials in the production of diamond tools processed via powder metallurgy. This work studies the influence of Fe on diamond graphitization diamond-coated Ti after mixing of Fe-diamonds, hot pressing parameters were performed with 3 minutes/35MPa/900 deg C - this is the condition of pressing hot used in industry for production of diamond tools. Microstructural features were observed by SEM, diffusion of Fe in diamond was studied by EDS. Graphitization was analyzed by X-ray diffraction and Raman spectroscopy. It was found that Fe not activate graphitization on the diamond under the conditions of hot pressing. (author)
Luiz Carlos Campos Braga
2011-08-01
Full Text Available OBJETIVO: o objetivo deste estudo foi verificar a fricção no braquete (Roth, Composite, 10.17.005, 3,2mm, largura 0,022" x 0,030", Torque -2° e angulação +13°, Morelli®, Brasil, utilizando fios ortodônticos retangulares de 0,019" x 0,025" de aço inoxidável (Morelli®, Brasil e de níquel-titânio superelásticos Bioforce com IonGuard e sem IonGuard (Bioforce, GAC®, EUA. MÉTODOS: foram utilizados 24 conjuntos braquetes/segmento de fio, divididos em 3 grupos de acordo com o fio. Cada conjunto braquete/segmento de fio foi testado 3 vezes e obtida uma média. Os ensaios foram realizados em máquina universal de ensaios EMIC DL2000®. Os dados foram submetidos à Análise de Variância com significância de 95%. RESULTADOS: o fio retangular Bioforce com IonGuard apresentou fricção significativamente menor que o Bioforce sem IonGuard, porém sem diferença do fio de aço inoxidável. Entretanto, o coeficiente de variação dos fios Bioforce com e sem IonGuard foi menor que o do fio de aço inoxidável. CONCLUSÃO: os fios retangulares de 0,019" x 0,025" Bioforce com IonGuard apresentam menor fricção que o fio Bioforce sem IonGuard, sem diferença para o fio de aço inoxidável.OBJECTIVE: The aim of this study was to evaluate the friction forces on brackets (Roth, Composite, 10.17.005, 3.2 mm, width 0.022" x 0.030 ", Torque -2° and angulation +13°, Morelli®, Brazil, with stainless steel orthodontic rectangular wire (Morelli®, Brazil and nickel titanium superelastic Bioforce wires with and without IonGuard (Bioforce, GAC®, USA. MATERIAL AND METHODS: Twenty-four brackets/wire segment combinations were used, distributed into three groups according to the orthodontic wire. Each bracket/wire segment combination was tested three times. The tests were performed in a universal testing machine Emic DL2000®. The data was submitted to ANOVA one way followed by Tukey's post hoc test (p<0.05. RESULTS: The rectangular orthodontic Bioforce wire
Deise Lima Cunha Masioli
2011-02-01
Full Text Available OBJETIVO: avaliar a influência do tratamento de superfície de resinas acrílicas na resistência ao cisalhamento de braquetes colados com resina composta. MÉTODOS: foram confeccionados 140 discos de resina acrílica autopolimerizável (Duralay®, divididos aleatoriamente em 14 grupos (n=10. Em cada grupo, os corpos de prova receberam um tipo diferente de tratamento de superfície: grupo 1 = sem tratamento de superfície (controle; grupo 2 = silano; grupo 3 = jato de óxido de alumínio (JOA; grupo 4 = JOA + silano; grupo 5 = broca diamantada; grupo 6 = broca diamantada+ silano; grupo 7 = ácido fluorídrico; grupo 8 = ácido fluorídrico + silano; grupo 9 = ácido fosfórico; grupo 10 = ácido fosfórico + silano; grupo 11 = monômero de metilmetacrilato (MMA; grupo 12 = MMA + silano; grupo 13 = Plastic conditioner (Reliance®; grupo 14 = Plastic conditioner (Reliance® + silano. Após o preparo de superfície, os corpos de prova foram analizados através da rugosimetria. Posteriormente, foram colados braquetes (Morelli® de incisivo central "standard edgewise" com resina fotopolimerizável Transbond XT®; de acordo com as instruções do fabricante. RESULTADOS: o agente umectante à base de silano não teve um efeito estatisticamente significativo sobre os valores de força de adesão; os tratamentos com JOA e broca produziram maiores mudanças topográficas na superfície da resina acrílica, bem como os maiores valores de rugosidade; observou-se uma correlação não linear entre a força de adesão e a rugosidade de superfície; tratamentos com monômero e JOA resultaram nas maiores forças de adesão. CONCLUSÕES: o silano não foi capaz de aumentar a força de adesão entre braquete e resina acrílica. Sugere-se mais estudos sobre este tema, pois a força de adesão obtida foi muito baixa.OBJECTIVE: To evaluate the influence of the surface treatment of acrylic resins on the shear bond strength of brackets bonded with composite resin
Jefferson Vinicius Bozelli
2013-12-01
Full Text Available OBJECTIVE: The aim of this study was to assess the time spent for direct (DBB - direct bracket bonding and indirect (IBB - indirect bracket bonding bracket bonding techniques. The time length of laboratorial (IBB and clinical steps (DBB and IBB as well as the prevalence of loose bracket after a 24-week follow-up were evaluated. METHODS: Seventeen patients (7 men and 10 women with a mean age of 21 years, requiring orthodontic treatment were selected for this study. A total of 304 brackets were used (151 DBB and 153 IBB. The same bracket type and bonding material were used in both groups. Data were submitted to statistical analysis by Wilcoxon non-parametric test at 5% level of significance. RESULTS: Considering the total time length, the IBB technique was more time-consuming than the DBB (p < 0.001. However, considering only the clinical phase, the IBB took less time than the DBB (p < 0.001. There was no significant difference (p = 0.910 for the time spent during laboratorial positioning of the brackets and clinical session for IBB in comparison to the clinical procedure for DBB. Additionally, no difference was found as for the prevalence of loose bracket between both groups. CONCLUSION: the IBB can be suggested as a valid clinical procedure since the clinical session was faster and the total time spent for laboratorial positioning of the brackets and clinical procedure was similar to that of DBB. In addition, both approaches resulted in similar frequency of loose bracket.
Generalized nonholonomic mechanics, servomechanisms and related brackets
Cendra, H.; Grillo, S.
2006-02-01
It is well known that nonholonomic systems obeying D'Alembert's principle are described on the Hamiltonian side, after using the Legendre transformation, by the so-called almost-Poisson brackets. In this paper we define the Lagrangian and Hamiltonian sides of a class of generalized nonholonomic systems (GNHS), obeying a generalized version of D'Alembert's principle, such as rubber wheels (like some simplified models of pneumatic tires) and certain servomechanisms (like the controlled inverted pendulum), and show that corresponding equations of motion can also be described in terms of a bracket. We present essentially all possible brackets in terms of which the mentioned equations can be written down, which include the brackets that appear in the literature, and point out those (if any) that are naturally related to each system. In particular, we show there always exists a Leibniz bracket related to a GNHS, and conversely, that every Leibniz system is a GNHS. The control of the inverted pendulum on a cart is studied as an illustrative example.
Frictional Resistance of Three Types of Ceramic Brackets
Claire L Williams
2014-01-01
Full Text Available Objectives: To investigate the static frictional resistance at the bracket/archwire interface in two recently introduced bracket systems and compare them to conventional ceramic and conventional metal bracket systems. Three variables were considered including the bracket system, archwire type and archwire angulation. Material and Methods: Four bracket systems were tested in vitro: Self ligating ceramic, ceramic with metal slot and module, conventional ceramic with module and conventional metal with module. A specially constructed jig and an Instron testing machine were used to measure the static frictional resistance for 0.014 inches round and 0.018 x 0.025 inches rectangular stainless steel wires at 0° and 7° angulations. Main outcome measures: static frictional force at the bracket/archwire interface; recorded and measured in units of force (Newtons. Results: Self ligating ceramic and metal slot ceramic bracket systems generated significantly less static frictional resistance than conventional ceramic bracket systems with the wire at both angulations (P < 0.05. Changing the wire from 0.014 round to 0.018 x 0.025 rectangular wire significantly increased frictional forces for metal slot ceramic and conventional metal bracket systems (P < 0.01. Increasing wire angulation significantly increased frictional resistance at the bracket/archwire interface for all four types of bracket systems tested (P < 0.001. Conclusions: Compared to conventional ceramic, self ligating ceramic and metal slot ceramic bracket systems should give improved clinical performance, matching that of conventional metal brackets.
A stainless steel bracket for orthodontic application.
Oh, Keun-Taek; Choo, Sung-Uk; Kim, Kwang-Mahn; Kim, Kyoung-Nam
2005-06-01
Aesthetics has become an essential element when choosing orthodontic fixed appliances. Most metallic brackets used in orthodontic therapy are made from stainless steel (SS) with the appropriate physical properties and good corrosion resistance, and are available as types 304, 316 and 17-4 PH SS. However, localized corrosion of these materials can frequently occur in the oral environment. This study was undertaken to evaluate the accuracy of sizing, microstructure, hardness, corrosion resistance, frictional resistance and cytotoxicity of commercially available Mini-diamond (S17400), Archist (S30403) and experimentally manufactured SR-50A (S32050) brackets. The size accuracy of Mini-diamond was the highest at all locations except for the external horizontal width of the tie wing (P SS brackets. PMID:15947222
Dirac brackets for the chiral Schwinger model with chiral constraint
Dirac brackets for the chiral Schwinger model with chiral constraint are derived perturbatively from the correlation function by the BJL limit method. The results show that the Poissons brackets are not consistent in this theory. (author)
Color stability of ceramic brackets immersed in potentially staining solutions
Guignone, Bruna Coser; Silva, Ludimila Karsbergen; Soares, Rodrigo Villamarim; Akaki, Emilio; Goiato, Marcelo Coelho; PITHON, Matheus Melo; Oliveira, Dauro Douglas
2015-01-01
OBJECTIVE: To assess the color stability of five types of ceramic brackets after immersion in potentially staining solutions. METHODS: Ninety brackets were divided into 5 groups (n = 18) according to brackets commercial brands and the solutions in which they were immersed (coffee, red wine, coke and artificial saliva). The brackets assessed were Transcend (3M/Unitek, Monrovia, CA, USA), Radiance (American Orthodontics, Sheboygan, WI, USA), Mystique (GAC International Inc., Bohemia, NY, USA) a...
Medeiros, R.L.B.A.; Melo, D.M.A.; Melo, M.A.F. [Universidade Federal do Rio Grande do Norte, Natal, RN (Brazil); Souza, K.S.G.M. [Universidade Federal da Paraiba - Departamento de Engenharia Quimica, PB (Brazil); Barros, J.M.F. [Universidade Federal de Campina Grande - Campos Cuite, PB (Brazil)
2010-07-01
The mixed metal oxides constitute an important class of catalytic materials widely investigated in different fields of applications. Studies of rare earth nickelates have been carried by several researchers in order to investigate the structural stability afforded by oxide formed and the existence of catalytic properties at room temperature. So, this study aims synthesize the nano sized catalyst of nickelate of lanthanum doped with strontium (La(1- x)Sr{sub x}NiO4-{sigma}; x = 0,2 and 0,3), through the Pechini method and your characterization for subsequent application in the desulfurization of thiophene reaction. The precursor solutions were calcined at 300 degree C/2h for pyrolysis of polyester and later calcinations occurred at temperatures of 500 - 1000 degree C. The resulting powders were characterized by thermogravimetric analysis (TG / DTG), surface area for adsorption of N{sub 2} by BET method, Xray diffraction (XRD), scanning electron microscopy (HR{sub S}EM) and spectrometry dispersive energy (EDS). The results of XRD had show that the perovskites obtained consist of two phases (LSN and NiO) and from 700 degree C have crystalline structure. The results of SEM evidenced the obtainment of nano metric powders. The results of BET show that the powders have surface area within the range used in catalysis (5-50m{sup 2}/g). The characterization of active sites was performed by reaction of desulfurization of thiophene at room temperature and 200 degree C, the relation F/W equal to 0,7 mol h{sup -1}m{sub c}at {sup -1}. The products of the reaction were separated by gas chromatography and identified by the selective detection PFPD sulfur. All samples had presented conversion above 95%. (author)
21 CFR 872.5470 - Orthodontic plastic bracket.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Orthodontic plastic bracket. 872.5470 Section 872...) MEDICAL DEVICES DENTAL DEVICES Therapeutic Devices § 872.5470 Orthodontic plastic bracket. (a) Identification. An orthodontic plastic bracket is a plastic device intended to be bonded to a tooth to...
26 CFR 31.3402(c)-1 - Wage bracket withholding.
2010-04-01
... 26 Internal Revenue 15 2010-04-01 2010-04-01 false Wage bracket withholding. 31.3402(c)-1 Section... SOURCE Collection of Income Tax at Source § 31.3402(c)-1 Wage bracket withholding. (a) In general. (1) The employer may elect to use the wage bracket method provided in section 3402(c) instead of...
Boundary values as Hamiltonian variables: new Poisson brackets
It is shown that the standard Poisson brackets in field theory can be modified by adding some surface terms. The definition of the Poisson brackets permits to treat boundary values of a field on equal footing with its internal values and directly estimate the brackets between both surface and volume integrals. 8 refs
Quantization and Dynamisation of Trace-Poisson Brackets
Avan, Jean; Ragoucy, Eric; Rubtsov, Vladimir
2016-01-01
The quantization problem for the trace-bracket algebra, derived from double Poisson brackets, is discussed. We obtain a generalization of the boundary YBE (or so-called ABCD-algebra) for the quantization of quadratic trace-brackets. A dynamical deformation is proposed on the lines of Gervais-Neveu-Felder dynamical quantum algebras.
Algebras of Jordan brackets and Generalized Poisson algebras
Kaygorodov, Ivan
2015-01-01
We construct a basis of free unital generalized Poisson superalgebras and a basis of free unital superalgebras of Jordan brackets. Also, we prove the analogue of Farkas' Theorem for PI unital generalized Poisson algebras and PI unital algebras of Jordan brackets. Relations beetwen generic Poisson superalgebras and superalgebras of Jordan brackets will be studied.
Quantization and dynamisation of Trace-Poisson brackets
Avan, Jean; Ragoucy, Eric; Rubtsov, Vladimir
2014-01-01
The quantization problem for the trace-bracket algebra, derived from double Poisson brackets, is discussed. We obtain a generalization of the boundary YBE (or so-called ABCD-algebra) for the quantization of quadratic trace-brackets. A dynamical deformation is proposed on the lines of Gervais-Neveu-Felder dynamical quantum algebras.
Cláudio Pereira Viana
2005-06-01
Full Text Available Este trabalho procurou avaliar, através do Método dos Elementos Finitos, a resistência ao deslocamento de quatro diferentes bases de braquetes "straight-wire" (Morelli, Unitek, A-Company e Abzil-Lancer na aplicação de forças de torção e cisalhamento, correlacionando essa resistência à melhor adaptação das bases à superfície vestibular dentária. As curvaturas das bases de braquetes utilizados no presente estudo foram descritas em um estudo prévio, enquanto o contorno dentário foi obtido a partir do escaneamento e cálculo da curvatura média vestibular do canino inferior de uma amostra de 30 indivíduos brasileiros. Empregou-se a análise tridimensional por Elementos Finitos da interface esmalte vestibular/cimento/base do braquete para cada marca testada. Forças de 1N, promovendo deslocamento lateral e torção, foram aplicadas no centro da base do braquete e observou-se a distribuição desses esforços sobre os modelos assim como as tensões normais e de cisalhamento geradas. Os resultados mostraram que a base que melhor se adaptou à superfície vestibular construída foi a da marca Unitek, seguida pela marca A-Company, Abzil-Lancer e Morelli. As deformações sofridas pelos braquetes foram inversamente proporcionais à adaptação à superfície dentária. Os maiores picos de tensão localizaram-se nas proximidades do ponto de aplicação da força. A interface adesivo/esmalte foi mais sujeita à falha na adesão que a interface braquete/adesivo. A força de cisalhamento demonstrou ser mais provável de causar falha na adesão quando comparada à força de torção.The objective of this study was to evaluate the adaptability of the four straight-wire brackets bases (Morelli, Unitek, A-Company and Abzil-Lancer to facial surface of a lower canine. The lower canine facial curvature data to be used in the three-dimensional finite element model were established by 30 Brazilian adult individuals and the brackets bases curvature
An infinite algebra of quantum Dirac brackets
A new algebraic approach to the theory with second-class constraints is proposed. The operator equations that generate automatically the infinite algebra of quantum Dirac brackets are formulated. First-class constraints are naturally involved into the new algebraic scheme. (orig.)
Integral invariants of the Buttin bracket
We study the densities (most general objects which may be integrated over supersurfaces in superspace), invariant with respect to supercanonical transformations which do not change the Buttin bracket. The only such nontrivial object is, in a definite sense, the odd semidensity explicitly constructed here. (orig.)
Path integral and noncommutative Poisson brackets
Valtancoli, P.
2015-06-01
We find that in presence of noncommutative Poisson brackets, the relation between Lagrangian and Hamiltonian is modified. We discuss this property by using the path integral formalism for non-relativistic systems. We apply this procedure to the harmonic oscillator with a minimal length.
Path integral and noncommutative poisson brackets
Valtancoli, P.
2015-01-01
We find that in presence of noncommutative poisson brackets the relation between Lagrangian and Hamiltonian is modified. We discuss this property by using the path integral formalism for non-relativistic systems. We apply this procedure to the harmonic oscillator with a minimal length.
Translucency of Dental Ceramic, Post and Bracket
Yong-Keun Lee
2015-10-01
Full Text Available Translucency of dental ceramics, esthetic posts and orthodontic brackets was reviewed. Translucency parameter (TP and contrast ratio (CR are generally used for translucency evaluation. For the evaluation of translucency, two criteria such as the translucency of human teeth (TP = 15–19, 1 mm thick and the visual perceptibility threshold for the translucency difference (∆CR > 0.07 or ∆TP > 2 were used. In ceramics, translucency differences were in the perceptible range depending on the type of material and the thickness. However, variations caused by the difference in the required thickness for each layer by the material and also by the measurement protocols should be considered. As to the translucency of esthetic posts, a significant difference was found among the post systems. Translucency was influenced by the bracket composition and brand, and the differences by the brand were visually perceptible.
Optimizing array spectroradiometer readings using adaptative bracketing
Deniel, Jean-Marc
2016-03-01
Single monochromator array spectroradiometers are convenient instruments for measuring spectral quantities in the UV-Vis-NIR range. They monitor the sensor array signal based on the same integration time for all wavelengths. However, the signal-to-noise ratio may be too low to provide useful readings at weaker signal wavelengths. The so-called "bracketing" technique overcomes this drawback by performing successive retrievals using different integration times, thereby ensuring that sufficiently high signal-to-noise ratio signals are recorded and non-relevant and low ratio signals are ignored. This paper proposes the use of an automated bracketing method based on the currently used array spectroradiometer noise models and analysis of retrieved spectra. Integration time at each array pixel fits spectral signal distribution with respect to a user-defined accuracy criterion and relevance constraints for the spectroradiometer used.
Hydrodynamic Nambu Brackets derived by Geometric Constraints
Blender, Richard
2015-01-01
A geometric approach to derive the Nambu brackets for ideal two-dimensional (2D) hydrodynamics is suggested. The derivation is based on two-forms with vanishing integrals in a periodic domain, and with resulting dynamics constrained by an orthogonality condition. As a result, 2D hydrodynamics with vorticity as dynamic variable emerges as a generic model, with conservation laws which can be interpreted as enstrophy and energy functionals. Generalized forms like surface quasi-geostrophy and fractional Poisson equations for the stream-function are also included as results from the derivation. The formalism is extended to a hydrodynamic system coupled to a second degree of freedom, with the Rayleigh-B\\'{e}nard convection as an example. This system is reformulated in terms of constitutive conservation laws with two additive brackets which represent individual processes: a first representing inviscid 2D hydrodynamics, and a second representing the coupling between hydrodynamics and thermodynamics. The results can b...
Conceptual design for PSP mounting bracket
Ransom, G.; Stein, R. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)
1991-12-31
Protective structural packages (PSP`s or overpacks) used to ship 2 1/2-ton UF{sub 6} product cylinders are bolted to truck trailers. All bolts penetrate two longitudinal rows of wooden planks. Removal and replacement is required at various intervals for maintenance and routine testing. A conceptual design is presented for mounting brackets which would securely attach PSP`s to trailer frames, reduce removal and replacement time, and minimize risk of personnel injury.
Nambu brackets in fluid mechanics and magnetohydrodynamics
Concrete examples of the construction of Nambu brackets for equations of motion (both 3D and 2D) of Boussinesq stratified fluids and also for magnetohydrodynamical equations are given. It serves a generalization of Hamiltonian formulation for the considered equations of motion. Two alternative Nambu formulations are proposed, first by using fluid dynamical (kinetic) helicity and/or enstrophy as constitutive elements and second, by using the existing conservation laws of the governing equation.
Hydrodynamic Nambu Brackets derived by Geometric Constraints
Blender, Richard; Badin, Gualtiero
2015-01-01
A geometric approach to derive the Nambu brackets for ideal two-dimensional (2D) hydrodynamics is suggested. The derivation is based on two-forms with vanishing integrals in a periodic domain, and with resulting dynamics constrained by an orthogonality condition. As a result, 2D hydrodynamics with vorticity as dynamic variable emerges as a generic model, with conservation laws which can be interpreted as enstrophy and energy functionals. Generalized forms like surface quasi-geostrophy and fra...
Conceptual design for PSP mounting bracket
Protective structural packages (PSP's or overpacks) used to ship 2 1/2-ton UF6 product cylinders are bolted to truck trailers. All bolts penetrate two longitudinal rows of wooden planks. Removal and replacement is required at various intervals for maintenance and routine testing. A conceptual design is presented for mounting brackets which would securely attach PSP's to trailer frames, reduce removal and replacement time, and minimize risk of personnel injury
Conceptual design for PSP mounting bracket
Protective structural packages (PSP's or overpacks) used to ship 2 1/2-ton UF product cylinders are bolted to truck trailers. All bolts penetrate two longitudinal rows of wooden planks. Removal and replacement is required at various intervals for maintenance and routine testing. A conceptual design is presented for mounting brackets which would securely attach PSP's to trailer frames, reduce removal and replacement time, and minimize risk of personnel injury. 1 ref., 2 figs
Toothpaste Prevents Debonded Brackets on Erosive Enamel
Barros, Érico Luiz Damasceno; Pinto, Shelon Cristina Souza; Borges, Alvaro Henrique; Tonetto, Mateus Rodrigues; Ellwood, Roger Phillip; Pretty, Ian; Bandéca, Matheus Coelho
2015-01-01
This study evaluated the effect of high fluoride dentifrice on the bond strength of brackets after erosive challenge. Eighty-four enamel specimens were divided into seven groups (n = 12): WN (distilled water/no acid challenge), W3C (distilled water/3 cycles of acid challenge), and W6C (distilled water/6 cycles of acid challenge) were not submitted to dentifrice treatment. Groups RF3C (regular fluoride dentifrice/3 cycles of acid challenge) and RF6C (regular fluoride dentifrice/6 cycles of acid challenge) were treated with dentifrices containing 1450 μg F−/g and HF3C (high fluoride dentifrice/3 cycles of acid challenge) and HF6C (high fluoride dentifrice/6 cycles of acid challenge) were with 5000 μg F−/g. Acid challenges were performed for seven days. After bond strength test, there was no significant difference among groups submitted to 3 cycles of acid challenge (P > 0.05). Statistically significant difference was found between the regular and high fluoride dentifrices after 6 cycles of acid challenge (<0.05). Similar areas of adhesive remaining were found among control groups and among groups W6C, RF3C, RF6C, HF3C, and HF6C. The high fluoride dentifrice was able to prevent the reduction of bond strength values of brackets submitted to acid challenge. Clinical relevance: the high fluoride toothpaste prevents debonded brackets on erosive enamel. PMID:25879058
Does the bracket composition material influence initial biofilm formation?
Gustavo Antônio Martins Brandão; Antonio Carlos Pereira; Ana Maria Martins Brandão; Haroldo Amorim de Almeida; Rogério Heládio Lopes Motta
2015-01-01
Context: Orthodontic treatment has been reported to contribute to the development and accumulation of dental biofilm, which is commonly found on bracket and adjacent surfaces. Aims: The aim of this work is to test the hypothesis if there are differences in dental biofilm formation on the surface of orthodontic brackets according to the type of composition material. Subjects and Methods: Three bracket types (metallic, composite, and ceramic) had been evaluated. Subjects wore acrylic pa...
On Covariant Poisson Brackets in Classical Field Theory
Forger, Michael; Salles, Mário O.
2015-01-01
How to give a natural geometric definition of a covariant Poisson bracket in classical field theory has for a long time been an open problem - as testified by the extensive literature on "multisymplectic Poisson brackets", together with the fact that all these proposals suffer from serious defects. On the other hand, the functional approach does provide a good candidate which has come to be known as the Peierls - De Witt bracket and whose construction in a geometrical setting is now well unde...
Peierls brackets in non-Lagrangian field theory
Sharapov, Alexey
2014-01-01
The concept of Lagrange structure allows one to systematically quantize the Lagrangian and non-Lagrangian dynamics within the path-integral approach. In this paper, I show that any Lagrange structure gives rise to a covariant Poisson brackets on the space of solutions to the classical equations of motion, be they Lagrangian or not. The brackets generalize the well-known Peierls' bracket construction and make a bridge between the path-integral and the deformation quantization of non-Lagrangian...
Peierls brackets in non-Lagrangian field theory
Sharapov, A. A.
2014-10-01
The concept of Lagrange structure allows one to systematically quantize the Lagrangian and non-Lagrangian dynamics within the path-integral approach. In this paper, I show that any Lagrange structure gives rise to a covariant Poisson bracket on the space of solutions to the classical equations of motion, be they Lagrangian or not. The bracket generalize the well-known Peierls' bracket construction and make a bridge between the path-integral and the deformation quantization of non-Lagrangian dynamics.
Peierls brackets in non-Lagrangian field theory
Sharapov, Alexey
2014-01-01
The concept of Lagrange structure allows one to systematically quantize the Lagrangian and non-Lagrangian dynamics within the path-integral approach. In this paper, I show that any Lagrange structure gives rise to a covariant Poisson brackets on the space of solutions to the classical equations of motion, be they Lagrangian or not. The brackets generalize the well-known Peierls' bracket construction and make a bridge between the path-integral and the deformation quantization of non-Lagrangian dynamics.
Laser-Aided Ceramic Bracket Debonding: A Comprehensive Review.
Ghazanfari, Rezvaneh; Nokhbatolfoghahaei, Hanieh; Alikhasi, Marzieh
2016-01-01
Different techniques have been introduced for the removal of ceramic brackets. Since the early 1990s, lasers have been used experimentally for debonding ceramic brackets. The goal of this study is to give a comprehensive literature review on laser-aided ceramic bracket debonding. PubMed and Google Scholar databases were used to identify dental articles with the following combination of key words: Ceramic brackets, Debonding, and Laser. Sixteen English articles from 2004 to 2015 were selected. The selected studies were categorized according to the variables investigated including the intrapulpal temperature, shear bond strength, debonding time, enamel damage and bracket failure. Most articles reported decreased shear bond strength and debonding time following laser irradiation without any critical and irritating increase in pulpal temperature. There were no reports of bracket failure or enamel damage. Laser irradiation is an efficient way to reduce shear bond strength of ceramic bracket and debonding time. This technique is a safe way for removing ceramic bracket with minimal impact on intrapulpal temperature and enamel surface and it reduces ceramic bracket failure. PMID:27330690
From Peierls brackets to a generalized Moyal bracket for type-I gauge theories
Esposito, G; Esposito, Giampiero; Stornaiolo, Cosimo
2006-01-01
In the space-of-histories approach to gauge fields and their quantization, the Maxwell, Yang--Mills and gravitational field are well known to share the property of being type-I theories, i.e. Lie brackets of the vector fields which leave the action functional invariant are linear combinations of such vector fields, with coefficients of linear combination given by structure constants. The corresponding gauge-field operator in the functional integral for the in-out amplitude is an invertible second-order differential operator. For such an operator, we consider advanced and retarded Green functions giving rise to a Peierls bracket among group-invariant functionals. Our Peierls bracket is a Poisson bracket on the space of all group-invariant functionals in two cases only: either the gauge-fixing is arbitrary but the gauge fields lie on the dynamical sub-space; or the gauge-fixing is a linear functional of gauge fields, which are generic points of the space of histories. In both cases, the resulting Peierls bracke...
The quaternionic commutator bracket and its implications
Arbab, Arbab I
2014-01-01
A quaternionic commutator bracket for position and momentum shows that the quaternionic wave function, \\emph{viz.} $\\widetilde{\\psi}=(\\frac{i}{c}\\,\\psi_0\\,,\\vec{\\psi})$, represents a state of a particle with orbital angular momentum, $L=3\\,\\hbar$, resulting from the internal structure of the particle. This angular momentum can be attributed to spin of the particle. The vector $\\vec{\\psi}$, points along the direction of $\\vec{L}$. When a charged particle is placed in an electromagnetic fields the interaction energy reveals that the magnetic moments interact with the electric and magnetic fields giving rise to terms similar to Aharonov-Bohm and Aharonov-Casher effects.
Brackets in representation algebras of Hopf algebras
Massuyeau, Gwenael; Turaev, Vladimir
2015-01-01
For any graded bialgebras $A$ and $B$, we define a commutative graded algebra $A_B$ representing the functor of so-called $B$-representations of $A$. When $A$ is a cocommutative graded Hopf algebra and $B$ is a commutative ungraded Hopf algebra, we introduce a method deriving a Gerstenhaber bracket in $A_B$ from a Fox pairing in $A$ and a balanced biderivation in $B$. Our construction is inspired by Van den Bergh's non-commutative Poisson geometry, and may be viewed as an algebraic generaliza...
Toothpaste Prevents Debonded Brackets on Erosive Enamel
Érico Luiz Damasceno Barros; Shelon Cristina Souza Pinto; Alvaro Henrique Borges; Mateus Rodrigues Tonetto; Roger Phillip Ellwood; Ian Pretty; Matheus Coelho Bandéca
2015-01-01
This study evaluated the effect of high fluoride dentifrice on the bond strength of brackets after erosive challenge. Eighty-four enamel specimens were divided into seven groups (n = 12): WN (distilled water/no acid challenge), W3C (distilled water/3 cycles of acid challenge), and W6C (distilled water/6 cycles of acid challenge) were not submitted to dentifrice treatment. Groups RF3C (regular fluoride dentifrice/3 cycles of acid challenge) and RF6C (regular fluoride dentifrice/6 cycles of aci...
Shintcovsk, Ricardo Lima; Luegya Amorim Henriques KNOP; Luiz Gonzaga GANDINI Jr; Lidia Parsekian MARTINS; Aline Segatto PIRES
2015-01-01
This study aims at comparing conventional and nickel-free metal bracket surface characteristics with elemental composition by scanning electron microscopy (SEM), using energy dispersive spectroscopy (EDS). The sample consisted of 40 lower incisor brackets divided into four groups: ABZ = conventional brackets, Kirium Abzil 3M® (n = 10); RL = conventional brackets, Roth Light Morelli® (n = 10); NF = nickel-free brackets, Nickel-Free Morelli® (n = 10); and RM = nickel-free brackets, Roth Max Mor...
Bahnasi, Faisal-Ismail; Abd-Rahman, Aida-Nur-Ashikin; Abu-Hassan, Mohamed-Ibrahim
2013-01-01
Objectives: 1) to assess different methods of recycling orthodontic brackets, 2) to evaluate Shear Bond Strength (SBS) of (a) new, (b) recycled and (c) repeated recycled stainless steel brackets (i) with and (ii) without bracket base primer. Study Design: A total of 180 extracted human premolar teeth and 180 premolar stainless steel brackets were used. One hundred teeth and 100 brackets were divided into five groups of 20-teeth each. Four methods of recycling orthodontic brackets were used in...
Hydrodynamic Nambu brackets derived by geometric constraints
Blender, Richard; Badin, Gualtiero
2015-03-01
A geometric approach to derive the Nambu brackets for ideal two-dimensional (2D) hydrodynamics is suggested. The derivation is based on two-forms with vanishing integrals in a periodic domain, and with resulting dynamics constrained by an orthogonality condition. As a result, 2D hydrodynamics with vorticity as dynamic variable emerges as a generic model, with conservation laws which can be interpreted as enstrophy and energy functionals. Generalized forms like surface quasi-geostrophy and fractional Poisson equations for the stream-function are also included as results from the derivation. The formalism is extended to a hydrodynamic system coupled to a second degree of freedom, with the Rayleigh-Bénard convection as an example. This system is reformulated in terms of constitutive conservation laws with two additive brackets which represent individual processes: a first representing inviscid 2D hydrodynamics, and a second representing the coupling between hydrodynamics and thermodynamics. The results can be used for the formulation of conservative numerical algorithms that can be employed, for example, for the study of fronts and singularities.
Hydrodynamic Nambu brackets derived by geometric constraints
A geometric approach to derive the Nambu brackets for ideal two-dimensional (2D) hydrodynamics is suggested. The derivation is based on two-forms with vanishing integrals in a periodic domain, and with resulting dynamics constrained by an orthogonality condition. As a result, 2D hydrodynamics with vorticity as dynamic variable emerges as a generic model, with conservation laws which can be interpreted as enstrophy and energy functionals. Generalized forms like surface quasi-geostrophy and fractional Poisson equations for the stream-function are also included as results from the derivation. The formalism is extended to a hydrodynamic system coupled to a second degree of freedom, with the Rayleigh–Bénard convection as an example. This system is reformulated in terms of constitutive conservation laws with two additive brackets which represent individual processes: a first representing inviscid 2D hydrodynamics, and a second representing the coupling between hydrodynamics and thermodynamics. The results can be used for the formulation of conservative numerical algorithms that can be employed, for example, for the study of fronts and singularities. (paper)
On quantization of systems based on the odd Poisson bracket
New quantum representation of the odd (with respect to the Grassmann grading) Poisson bracket are obtained, some of them, as demonstrated by the simplest example, are responsible for the quantization of the classical Hamilton's dynamics based on the odd Poisson bracket. 8 refs
Thoughts on brackets and dissipation: Old and new
Bracket formulations of two kinds of dynamical systems, called incomplete and complete, are reviewed and developed, including double bracket and metriplectic dynamics. Dissipation based on the Cartan-Killing metric is introduced. Various examples of incomplete and complete dynamics are discussed, including dynamics associated with three-dimensional Lie algebras.
Poisson brackets of the super-Hamiltonian and the supermomenta
The Poisson brackets of the super-Hamiltonian and the supermomenta are related to the commutators of the normal basis vectors on the space of embeddings. The Poisson brackets are calculated without requiring the super-Hamiltonian and the supermomenta to be weakly zero, contrary to the claim of Teitelboim
Hamiltonian dynamical systems with even and odd Poisson brackets
For the example of Witten's supersymmetric mechanics it is shown that not only an even but also an odd Poisson bracket is inherently present in Hamiltonian systems with equal numbers of pairs of Grassmann even and odd canonical variables. For such systems a duality is established between the even and odd integrals of the motion when the parity of the Poisson bracket is changed
Weyl ordering rule and new Lie bracket of quantum mechanics
Rakic, Z; Rakic, Zoran; Prvanovic, Slobodan
2003-01-01
The product of quantum mechanics is defined as the ordinary multiplication followed by the application of superoperator that orders involved operators. The operator version of Poisson bracket is defined being the Lie bracket which substitutes commutator in the von Neumann equation. These result in obstruction free quantization, with the ordering rule which coincides with Weyl ordering rule.
Mariana Ribeiro Pacheco
2011-02-01
Full Text Available INTRODUÇÃO: o atrito gerado na interface braquete/fio durante a mecânica de deslizamento pode reduzir a eficiência da movimentação ortodôntica. O método de ligação do fio ao braquete exerce importante papel na determinação desse atrito. MÉTODOS: o presente estudo comparou a força de atrito gerada por quatro tipos de braquetes autoligáveis (Time®; Damon 2®; In-Ovation R® e Smart Clip® com um grupo de braquetes ortodônticos convencionais (Dynalock® associados a ligaduras elásticas tradicionais (Dispens-A-Stix®, que serviu como grupo controle. A força de atrito estático foi mensurada através da máquina universal de ensaios EMIC® DL 500 com dois fios de aço inoxidável com secção transversal 0,018" e 0,017" x 0,025". RESULTADOS: a análise de variância ANOVA e o teste de Tukey mostraram baixos níveis de atrito nos quatro braquetes autoligáveis associados ao fio 0,018" (PINTRODUCTION: Friction generated at the bracket/archwire interface during sliding mechanics can reduce the efficiency of orthodontic movement. The ligation method employed to tie the archwire to the bracket plays an important role in determining this friction. METHODS: This study compared the frictional force generated by four different types of self-ligating brackets (Time™, Damon 2™, In-Ovation R™ and Smart Clip™ with a group of conventional orthodontic brackets (Dynalock™ that require the use of traditional elastomeric ligatures (ExDispens-A-Stix™, which served as the control group. Static friction force was measured using an EMIC DL™ 500 universal testing machine using stainless steel round 0.018-in and rectangular 0.017x0.025-in archwires. RESULTS: ANOVA and Tukey's test showed low levels of friction in the four self-ligating brackets in tests with the 0.018-in wire (P <0.05. However, the results noted when the self-ligating brackets were tested using 0.017x 0.025-in archwires showed high resistance to sliding in the self
A bracket design proposal for the first molar
Roberto Scalon
2010-07-01
Full Text Available Introduction: The advent of bracket bonding simplified the assembly of orthodontic braces, besides giving more comfort to the patient and decreasing the risk of decalcification. However, there is no first molar bracket with accessory tube and hooks in the market, except for the convertible type.Objective:To present a patent for utility model of a bracket Roth prescription, Straight-Wire technique for first molar, in order to facilitate orthodontic treatment where there is a need for placing accessories in second molars.Material and methods:This patent consists of a molar bracket for bonding, which contains a retentive base for this, similar to the bracket used in the Edgewise technique,with fins for placing alastic or metal ligature,but containing pre-angles and torques as the tubes of the molar Straight-Wire technique with Roth prescription.It also includes an accessory tube for placing arches or cantilevers and hooks for placing elastics.Results and conclusion:With this bracket design proposal it is possible to obtain an accessory that facilitates the inclusion of the second molar in the assembly of the orthodontic brace without the use of bands.Moreover, this bracket has fins for placing ligatures,accessory tube for placing arches or cantilevers and hooks for placing elastics.
Color stability of ceramic brackets immersed in potentially staining solutions
Bruna Coser Guignone
2015-08-01
Full Text Available OBJECTIVE: To assess the color stability of five types of ceramic brackets after immersion in potentially staining solutions.METHODS: Ninety brackets were divided into 5 groups (n = 18 according to brackets commercial brands and the solutions in which they were immersed (coffee, red wine, coke and artificial saliva. The brackets assessed were Transcend (3M/Unitek, Monrovia, CA, USA, Radiance (American Orthodontics, Sheboygan, WI, USA, Mystique (GAC International Inc., Bohemia, NY, USA and Luxi II (Rocky Mountain Orthodontics, Denver, CO, USA. Chromatic changes were analyzed with the aid of a reflectance spectrophotometer and by visual inspection at five specific time intervals. Assessment periods were as received from the manufacturer (T0, 24 hours (T1, 72 hours (T2, as well as 7 days (T3 and 14 days (T4 of immersion in the aforementioned solutions. Results were submitted to statistical analysis with ANOVA and Bonferroni correction, as well as to a multivariate profile analysis for independent and paired samples with significance level set at 5%.RESULTS: The duration of the immersion period influenced color alteration of all tested brackets, even though these changes could not always be visually observed. Different behaviors were observed for each immersion solution; however, brackets immersed in one solution progressed similarly despite minor variations.CONCLUSIONS: Staining became more intense over time and all brackets underwent color alterations when immersed in the aforementioned solutions.
Preliminary Process Design of ITER ELM Coil Bracket Brazing
LI, Xiangbin; SHI, Yi
2015-03-01
With the technical requirement of the International Thermonuclear Experimental Reactor (ITER) project, the manufacture and assembly technology of the mid Edge Localized Modes (ELM) coil was developed by the Institute of Plasma Physics, Chinese Academy of Science (ASIPP). As the gap between the bracket and the Stainless Steel jacketed and Mineral Insulated Conductor (SSMIC) can be larger than 0.5 mm instead of 0.01 mm to 0.1 mm as in normal industrial cases, the process of mid ELM coil bracket brazing to the SSMICT becomes quiet challenging, from a technical viewpoint. This paper described the preliminary design of ELM coil bracket brazing to the SSMIC process, the optimal bracket brazing curve and the thermal simulation of the bracket furnace brazing method developed by ANSYS. BAg-6 foil (Bag50Cu34Zn16) plus BAg-1a paste (Bag45CuZnCd) solders were chosen as the brazing filler. By testing an SSMICT prototype, it is shown that the average gap between the bracket and the SSMIC could be controlled to 0.2-0.3 mm, and that there were few voids in the brazing surface. The results also verified that the preliminary design had a favorable heat conducting performance in the bracket.
Desmistificando os braquetes autoligáveis Demystifying self-ligating brackets
Renata Sathler
2011-04-01
Full Text Available Atualmente, os braquetes autoligáveis têm sido associados a tratamentos mais rápidos e eficazes, o que desperta a curiosidade em compará-los ao sistema convencional. Ao contrário dos braquetes tradicionais, os autoligáveis não necessitam de ligaduras, sejam elásticas ou metálicas. A literatura é farta em concluir que essa característica diminui, ostensivamente, a resistência do atrito durante as mecânicas de deslize. Além disso, existem alegações sobre a dimimuição da necessidade de extrações e de expansão maxilar com o uso desses acessórios. Portanto, o objetivo dessa revisão de literatura foi buscar os mais novos estudos a respeito dos aparelhos autoligáveis atualmente utilizados nos tratamentos ortodônticos, confirmando ou retificando as especulações vigentes.Currently self-ligating brackets have been associated to faster and more efficient treatments, which arouse the curiosity to compare them to the conventional system. Unlike traditional appliances, self-ligating brackets do not require elastomeric or metal ligatures. The literature is abundant in concluding that this feature decreases, ostensibly, the friction resistance during the sliding mechanics. Moreover, there are reports on minimizing the need of extractions and maxillary expansion using these accessories. Therefore, the purpose of this literature review was to seek the newest studies about the self-ligating brackets currently used in orthodontic treatments, confirming or correcting current speculations.
Calculation of four-particle harmonic-oscillator transformation brackets
Germanas, D.; Kalinauskas, R. K.; Mickevičius, S.
2010-02-01
A procedure for precise calculation of the three- and four-particle harmonic-oscillator (HO) transformation brackets is presented. The analytical expressions of the four-particle HO transformation brackets are given. The computer code for the calculations of HO transformation brackets proves to be quick, efficient and produces results with small numerical uncertainties. Program summaryProgram title: HOTB Catalogue identifier: AEFQ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEFQ_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 1247 No. of bytes in distributed program, including test data, etc.: 6659 Distribution format: tar.gz Programming language: FORTRAN 90 Computer: Any computer with FORTRAN 90 compiler Operating system: Windows, Linux, FreeBSD, True64 Unix RAM: 8 MB Classification: 17.17 Nature of problem: Calculation of the three-particle and four-particle harmonic-oscillator transformation brackets. Solution method: The method is based on compact expressions of the three-particle harmonics oscillator brackets, presented in [1] and expressions of the four-particle harmonics oscillator brackets, presented in this paper. Restrictions: The three- and four-particle harmonic-oscillator transformation brackets up to the e=28. Unusual features: Possibility of calculating the four-particle harmonic-oscillator transformation brackets. Running time: Less than one second for the single harmonic-oscillator transformation bracket. References:G.P. Kamuntavičius, R.K. Kalinauskas, B.R. Barret, S. Mickevičius, D. Germanas, Nuclear Physics A 695 (2001) 191.
Poisson bracket on 1-forms and evolutionary partial differential equations
We introduce a bracket on 1-forms defined on J∞(S1,Rn), i.e. the infinite jet extension of the space of loops, and prove that it satisfies the standard properties of a Poisson bracket. Using this bracket, we show that certain hierarchies appearing in the framework of F-manifolds with a compatible flat connection (M, ∇, ○) are Hamiltonian in a generalized sense. Moreover, we show that if a metric g compatible with ∇ is also invariant with respect to ○, then this generalized Hamiltonian setup reduces to the standard one. (paper)
Corrosion behavior of self-ligating and conventional metal brackets
Maia, Lúcio Henrique Esmeraldo Gurgel; Lopes Filho, Hibernon; RUELLAS, Antônio Carlos de Oliveira; Araújo, Mônica Tirre de Souza; VAITSMAN, Delmo Santiago
2014-01-01
Objective To test the null hypothesis that the aging process in self-ligating brackets is not higher than in conventional brackets. Methods Twenty-five conventional (GN-3M/Unitek; GE-GAC; VE-Aditek) and 25 self-ligating (SCs-3M/Unitek; INs-GAC; ECs-Aditek) metal brackets from three manufacturers (n = 150) were submitted to aging process in 0.9% NaCl solution at a constant temperature of 37 ± 1ºC for 21 days. The content of nickel, chromium and iron ions in the solution collected at intervals ...
Brackets, sigma models and integrability of generalized complex structures
It is shown how derived brackets naturally arise in sigma-models via Poisson- or antibracket, generalizing a recent observation by Alekseev and Strobl. On the way to a precise formulation of this relation, an explicit coordinate expression for the derived bracket is obtained. The generalized Nijenhuis tensor of generalized complex geometry is shown to coincide up to a de-Rham closed term with the derived bracket of the structure with itself and a new coordinate expression for this tensor is presented. The insight is applied to two known two-dimensional sigma models in a background with generalized complex structure
Pillai, Ajith R.; Gangadharan, Anil; Kumar, Satheesh; Shah, Anwar
2014-01-01
Background and Objectives: The purpose of this study is to evaluate the frictional resistance generated by conventional stainless steel, radiance ceramic bracket, self-ligating and composite brackets using a 0.019 × 0.025 stainless steel straight length wires in a 022 slot and to select brackets based on their frictional characteristic. Methodology: In order to conduct this study, four different types of bracket system were selected of the mclaughlin-bennet-trevesi (MBT) discipline. They are Group 1 - stainless steel, Group 2 - composite bracket Group 3 - (American Orthodontics) radiance ceramic bracket Group 4 - self-ligating bracket (SLB) (Empower). In this study, five maxillary brackets of an arch of each type were used. All brackets are 0.022 × 0.028 in preadjusted edgewise appliance which simulates the dental arch. Five brackets were bonded to a stainless steel bar of dimension 150 mm × 25 mm × 3 mm. The bracket-arch wire units were submitted to mechanical test with an Instron universal testing machine 3365. A testing apparatus or holding jig was designed to hold the bracket during the mechanical test. Each sample was pulled at a speed of 6 mm for 1 min. Descriptive statistical information including mean and standard deviation of maximum friction force was calculated for each bracket wire combination. Interpretation and Conclusion: The SLB has the least friction among the four groups. The ceramic bracket showed the highest friction followed by stainless steel bracket, composite bracket, and SLB. PMID:25210359
Walter Leal de Moura
2004-06-01
Full Text Available Retenção dentária é a condição fisiopatológica em que o dente, uma vez chegado o seu momento fisiológico de erupção, apresenta algum impedimento para realizá-lo. O tratamento, com envolvimento cirúrgico-ortodôntico, visa deslocar o elemento dental para a correta posição na arcada dentária, sem causar danos aos elementos dentais adjacentes, restabelecendo a estética e a função. A colagem direta de botões e braquetes ortodônticos para tração de dentes inclusos transformou-se na técnica preferida, pois exige menor extensão cirúrgica e remoção de tecido para acesso à coroa dental. A pesquisa objetivou analisar a intensidade da força aplicada ao conjunto dente/artifício/fio de amarrilho, pelo tracionamento, e observar o local do rompimento. Utilizaram-se 45 pré-molares, conservados em soro fisiológico 0,9%, que foram divididos em 3 grupos (15 com braquetes, 15 com botões e 15 com telas. Os dentes foram fixados em canos de PVC preenchidos com resina acrílica e os acessórios fixados ao dente com resina autopolimerizável. Após a colagem dos acessórios ortodônticos, os dentes voltaram a ser conservados em soro fisiológico e o teste realizado após 72 horas, com a utilização de um sensor de força e um programa de computador (Logger Pro. Com os resultados, observou-se que o braquete resistiu a uma força média de 36,0N, sendo a junção fio/braquete o local menos resistente; o botão resistiu a uma força média de 41,2N, a junção fio/botão ortodôntico foi o local menos resistente e a tela resistiu a uma força média de 28,8N, sendo a junção dente/tela o local menos resistente.Restrained is the tooth which, reached its physiological moment of eruption, shows some obstruction to accomplish it. The treatment, with orthodontic-surgical involvement, type drives at to dislocate the dental element for right position in the dental arch, without to cause damages for adjacent dental element, re-establishing the
A twisted generalization of linear Poisson brackets of hydrodynamic type
We study a twisted generalization of linear Poisson brackets of hydrodynamic type, in which the Lie bracket is replaced by a Hom-Lie bracket. With some natural additional conditions, such structures correspond to the Hom-Novikov algebras introduced by Yau, which is the twisted version of Balinsky-Novikov's approach of constructing a Lie algebra from a Novikov algebra. Certain central extensions of this twisted generalization of linear Poisson brackets of hydrodynamic type are obtained from the bilinear forms on their corresponding Hom-Novikov algebras satisfying some invariance conditions. Finally, we give some examples of the infinite-dimensional Hom-Lie algebras constructed from the Hom-Novikov algebras. In particular, there is an interesting twisted generalization of the Virasoro algebra.
The Kauffman bracket and the Jones polynomial in quantum gravity
In the loop representation the quantum states of gravity are given by knot invariants. From general arguments concerning the loop transform of the exponential of the Chern-Simons form, a certain expansion of the Kauffman bracket knot polynomial can be formally viewed as a solution of the Hamiltonian constraint with a cosmological constant in the loop representation. The Kauffman bracket is closely related to the Jones polynomial. In this paper the operation of the Hamiltonian on the power expansions of the Kauffman bracket and Jones polynomials is analyzed. It is explicitly shown that the Kauffman bracket is a formal solution of the Hamiltonian constraint to third order in the cosmological constant. We make use of the extended loop representation of quantum gravity where the analytic calculation can be thoroughly accomplished. Some peculiarities of the extended loop calculus are considered and the significance of the results to the case of the conventional loop representation is discussed. (orig.)
Er:YAG laser metal and ceramic bracket debonding
Dostálová, Tat'jana; Remeš, Marek; Jelínková, Helena; Å ulc, Jan; Němec, Michal; Vyhlídal, David
2016-02-01
The goal of the study was investigation of Er:YAG radiation (wavelength 2.94 μm) interaction with various metal and ceramic brackets and adhesive materials. The source of radiation was a free-running Er: YAG laser generating pulses with energy 280 mJ, 250 μs long and repetition rate 6 Hz (mean power 1.7 W). During the treatment lasting 140 s, water cooling was implemented and only the brackets were irradiated. It has been observed that the brackets were removed easily after the Er:YAG laser irradiation, and temperature rise was limited also for metal brackets. SEM investigation has confirmed less damage of enamel in comparison with non-irradiated samples.
Time-dependent constrained Hamiltonian systems and Dirac brackets
In this paper the canonical Dirac formalism for time-dependent constrained Hamiltonian systems is globalized. A time-dependent Dirac bracket which reduces to the usual one for time-independent systems is introduced. (author)
Evaluation of the Friction of Self-Ligating and Conventional Bracket Systems
Tecco, Simona; Di Iorio, Donato; Nucera, Riccardo; Di Bisceglie, Beatrice; Cordasco, Giancarlo; Festa, Felice
2011-01-01
Objectives: This in vitro study evaluated the friction (F) generated by aligned stainless steel (SS) conventional brackets, self-ligating Damon MX© brackets (SDS Ormco, Glendora, California, USA), Time3© brackets (American Orthodontics, Sheboygan, Wisconsin, USA), Vision LP© brackets (American Orthodontics), and low-friction Slide© ligatures (Leone, Firenze, Italy) coupled with various SS, nickel-titanium (NiTi), and beta-titanium (TMA) archwires. Methods: All brackets had a 0.022-inch slot, ...
Galvanic Corrosion among Different Combination of Orthodontic Archwires and Stainless Steel Brackets
Farzin Heravi; Nima Mokhber; Elnaz Shayan
2014-01-01
Introduction: The aim of this study was to assess the galvanic behavior of different bracket and archwire combinations that are commonly used in orthodontic treatments. Methods: Three types of orthodontic archwires with a diameter of 0.016×0.022 inch and 80 standard edgewise maxillary central incisor brackets were selected. Three groups consisted of different wire-bracket couples and one group was just brackets as a control group. Each group had five samples. Four brackets were then connected...
Comparison of frictional resistance of esthetic and semi-esthetic self-ligating brackets
Kannan, M. S.; Murali, R. V.; S Kishorekumar; Gnanashanmugam, K.; Jayanth, V.
2015-01-01
Aim: The frictional resistance encountered during sliding mechanics has been well established in the orthodontic literature, and it consists of complex interactions between the bracket, archwire, and method of ligation the claim of reduced friction with self-ligating brackets is often cited as a primary advantage over conventional brackets. This study was done to compare and evaluate the frictional forces generated between fully esthetic brackets and semi-aesthetic self-ligating brackets, whi...
Pasha, Azam; Vishwakarma, Swati; Narayan, Anjali; Vinay, K; Shetty, Smitha V; Roy, Partha Pratim
2015-01-01
Background: Fixed orthodontic mechanotherapy is associated with friction between the bracket - wire - ligature interfaces during the sliding mechanics. A sound knowledge of the various factors affecting the magnitude of friction is of paramount importance. The present study was done to analyze and compare the frictional forces generated by a new ceramic (Clarity Advanced) bracket with the conventional, (metal and ceramic) brackets using unconventional and conventional ligation system, and the self-ligating (metal and ceramic) brackets in the dry condition. Materials and Methods: The various bracket wire ligation combinations were tested in dry condition. The brackets used were of 0.022″ × 0.028″ nominal slot dimension of MBT prescription: Stainless steel (SS) self-ligating bracket (SLB) of (SmartClip), SS Conventional bracket (CB) (Victory series), Ceramic SLB (Clarity SL), Conventional Ceramic bracket with metal slot (Clarity Bracket), Clarity Advanced Ceramic Brackets (Clarity™ ADVANCED, 3M Unitek). These brackets were used with two types of elastomeric ligatures: Conventional Elastomeric Ligatures (CEL) (Clear medium mini modules) and Unconventional Elastomeric Ligatures (UEL) (Clear medium slide ligatures, Leone orthodontic products). The aligning and the retraction wires were used, i.e., 0.014″ nickel titanium (NiTi) wires and 0.019″ × 0.025″ SS wires, respectively. A universal strength testing machine was used to measure the friction produced between the different bracket, archwires, and ligation combination. This was done with the use of a custom-made jig being in position. Results: Mean, standard deviation, and range were computed for the frictional values obtained. Results were subjected to statistical analysis through ANOVA. The frictional resistance observed in the new Clarity Advanced bracket with a conventional elastomeric ligature was almost similar with the Clarity metal slot bracket with a conventional elastomeric ligature. When using
Histological evaluation after electrothermal debonding of ceramic brackets
Vignesh Kailasam; Ashima Valiathan; Nirmala Rao
2014-01-01
Aim: To evaluate the histological changes following electrothermal debonding (ETD) of ceramic brackets. Materials and Methods: A total of 50 first premolar teeth from 14 patients were divided into two groups: Group I consisted of 20 teeth which served as control, and the brackets were debonded using conventional pliers. (7 teeth were extracted 24 hours after conventional debonding, 7 teeth were extracted 28 to 32 days after conventional debonding and 6 teeth were extracted 56-60 days afte...
Hessian matrix, specific heats, Nambu brackets, and thermodynamic geometry
Mansoori, Seyed; Mirza, Behrouz; Fazel, Mohamadreza
2015-01-01
As an extension to our earlier work \\cite{Mirza2}, we employ the Nambu brackets to prove that the divergences of heat capacities correspond to their counterparts in thermodynamic geometry. We also obtain a simple representation for the conformal transformations that connect different thermodynamics metrics to each other. Using our bracket approach, we obtain interesting exact relations between the Hessian matrix with any number of parameters and specific heat capacities. Finally, we employ th...
Gerstenhaber brackets on Hochschild cohomology of twisted tensor products
Grimley, Lauren; Nguyen, C; Witherspoon, Sarah
2015-01-01
We construct the Gerstenhaber bracket on Hochschild cohomology of a twisted tensor product of algebras, and, as examples, compute Gerstenhaber brackets for some quantum complete intersections arising in work of Buchweitz, Green, Madsen, and Solberg. We prove that a subalgebra of the Hochschild cohomology ring of a twisted tensor product, on which the twisting is trivial, is isomorphic, as Gerstenhaber algebras, to the tensor product of the respective subalgebras of the Hochschild cohomology r...
DEBONDING OF CERAMIC BRACKETS BY ER:YAG LASER
Fidan ALAKUŞ-SABUNCUOĞLU; ERŞAHAN, Şeyda; ERTÜRK, Ergül
2016-01-01
Purpose: The objective of the present study is to evaluate the effects of Er:YAG laser debonding of ceramic brackets on the bond strength and the amount of adhesive resin remnant. Materials and Methods: Twenty human mandibular incisors were randomly divided into two groups of 10 and polycrystalline ceramic brackets (Transcend series 6000, 3M Unitek, Monrovia, CA, USA) were bonded on enamel surfaces. Group 1 was the control group in which no laser application was ...
Corrosion behavior of self-ligating and conventional metal brackets
Maia, Lúcio Henrique Esmeraldo Gurgel; Lopes Filho, Hibernon; Ruellas, Antônio Carlos de Oliveira; Araújo, Mônica Tirre de Souza; Vaitsman, Delmo Santiago
2014-01-01
Objective To test the null hypothesis that the aging process in self-ligating brackets is not higher than in conventional brackets. Methods Twenty-five conventional (GN-3M/Unitek; GE-GAC; VE-Aditek) and 25 self-ligating (SCs-3M/Unitek; INs-GAC; ECs-Aditek) metal brackets from three manufacturers (n = 150) were submitted to aging process in 0.9% NaCl solution at a constant temperature of 37 ± 1ºC for 21 days. The content of nickel, chromium and iron ions in the solution collected at intervals of 7, 14 and 21 days was quantified by atomic absorption spectrophotometry. After the aging process, the brackets were analyzed by scanning electron microscopy (SEM) under 22X and 1,000X magnifications. Results Comparison of metal release in self-ligating and conventional brackets from the same manufacturer proved that the SCs group released more nickel (p < 0.05) than the GN group after 7 and 14 days, but less chromium (p < 0.05) after 14 days and less iron (p < 0.05) at the three experimental time intervals. The INs group released less iron (p < 0.05) than the GE group after 7 days and less nickel, chromium and iron (p < 0.05) after 14 and 21 days. The ECs group released more nickel, chromium and iron (p < 0.05) than the VE group after 14 days, but released less nickel and chromium (p < 0.05) after 7 days and less chromium and iron (p < 0.05) after 21 days. The SEM analysis revealed alterations on surface topography of conventional and self-ligating brackets. Conclusions The aging process in self-ligating brackets was not greater than in conventional brackets from the same manufacturer. The null hypothesis was accepted. PMID:24945521
Microleakage under orthodontic brackets bonded with different adhesive systems
Alkis, Huseyin; Turkkahraman, Hakan; Adanir, Necdet
2015-01-01
Objective: This in vitro study aimed to compare the microleakage of orthodontic brackets between enamel-adhesive and adhesive-bracket interfaces at the occlusal and gingival margins bonded with different adhesive systems. Materials and Methods: A total of 144 human maxillary premolar teeth extracted for orthodontic reasons was randomly divided into four groups. Each group was then further divided into three sub-groups. Three total-etching bonding systems (Transbond XT, Greengloo and Kurasper ...
Corrosion behavior of self-ligating and conventional metal brackets
Lúcio Henrique Esmeraldo Gurgel Maia
2014-04-01
Full Text Available Objective: To test the null hypothesis that the aging process in self-ligating brackets is not higher than in conventional brackets. Methods: Twenty-five conventional (GN-3M/Unitek; GE-GAC; VE-Aditek and 25 self-ligating (SCs-3M/Unitek; INs-GAC; ECs-Aditek metal brackets from three manufacturers (n = 150 were submitted to aging process in 0.9% NaCl solution at a constant temperature of 37 ± 1ºC for 21 days. The content of nickel, chromium and iron ions in the solution collected at intervals of 7, 14 and 21 days was quantified by atomic absorption spectrophotometry. After the aging process, the brackets were analyzed by scanning electron microscopy (SEM under 22X and 1,000X magnifications. Results: Comparison of metal release in self-ligating and conventional brackets from the same manufacturer proved that the SCs group released more nickel (p < 0.05 than the GN group after 7 and 14 days, but less chromium (p < 0.05 after 14 days and less iron (p < 0.05 at the three experimental time intervals. The INs group released less iron (p < 0.05 than the GE group after 7 days and less nickel, chromium and iron (p < 0.05 after 14 and 21 days. The ECs group released more nickel, chromium and iron (p < 0.05 than the VE group after 14 days, but released less nickel and chromium (p < 0.05 after 7 days and less chromium and iron (p < 0.05 after 21 days. The SEM analysis revealed alterations on surface topography of conventional and self-ligating brackets. Conclusions: The aging process in self-ligating brackets was not greater than in conventional brackets from the same manufacturer. The null hypothesis was accepted.
In vitro tooth cleaning efficacy of electric toothbrushes around brackets
Schätzle, M; Sener, B.; Schmidlin, P.R; Imfeld, T; Attin, T.
2010-01-01
This in vitro study assessed the cleaning efficacy of different electric toothbrushes around upper incisor brackets. Standard and Mini Diamond™ brackets were fixed on black-stained teeth. The teeth were coated with white titanium oxide and brushed in a machine twice for 1 minute each. Twelve different brush heads with either a wiping or an oscillating-rotating action were tested. After brushing, the teeth were scanned, the black surfaces were assessed planimetrically and a modified plaque ind...
On Goldman bracket for G 2 gauge group
Chowdhury, S. Hasibul Hassan
2016-02-01
In this paper, we obtain an infinite dimensional Lie algebra of exotic gauge invariant observables that is closed under Goldman-type bracket associated with monodromy matrices of flat connections on a compact Riemann surface for G 2 gauge group. As a byproduct, we give an alternative derivation of known Goldman bracket for classical gauge groups GL ( n, ℝ), SL( n, ℝ), U( n), SU( n), Sp(2 n, ℝ) and SO( n).
Microleakage under orthodontic brackets bonded with different adhesive systems
Alkis, Huseyin; Turkkahraman, Hakan; Adanir, Necdet
2015-01-01
Objective: This in vitro study aimed to compare the microleakage of orthodontic brackets between enamel-adhesive and adhesive-bracket interfaces at the occlusal and gingival margins bonded with different adhesive systems. Materials and Methods: A total of 144 human maxillary premolar teeth extracted for orthodontic reasons was randomly divided into four groups. Each group was then further divided into three sub-groups. Three total-etching bonding systems (Transbond XT, Greengloo and Kurasper F), three one-step self-etching bonding systems (Transbond Plus SEP, Bond Force and Clearfil S3), three two-step self-etching bonding systems (Clearfil SE Bond, Clearfil Protectbond and Clearfil Liner Bond), and three self-adhesive resin cements (Maxcem Elite, Relyx U 100 and Clearfil SA Cement) were used to bond the brackets to the teeth. After bonding, all teeth were sealed with nail varnish and stained with 0.5% basic fuchsine for 24 h. All samples were sectioned and examined under a stereomicroscope to score for microleakage at the adhesive–enamel and adhesive–bracket interfaces from both occlusal and gingival margins. Statistical Analysis Used: Statistical analyses were performed with Kruskal–Wallis and Wilcoxon signed-rank tests. Results: The results indicate no statistically significant differences between the microleakage scores of the adhesives; microleakage was detected in all groups. Comparison of the average values of the microleakage scores in the enamel–adhesive and adhesive–bracket interfaces indicated statistically significant differences (P < 0.05). The amount of the microleakage was higher at the enamel–adhesive interface than at the bracket-adhesive interface. Conclusions: All of the brackets exhibited some amount of microleakage. This result means that microleakage does not depend on the type of adhesive used. PMID:25713494
Restivo, T.A. Guisard; Mello-Castanho, S.R.H. [Instituto de Pesquisas Energeticas e Nucleares (CCTM/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia dos Materiais; Leite, D. Will [Instituto de Pesquisas e Estudos Industriais (IPEI/FEI), Sao Bernardo do Campo, SP (Brazil). Fac. de Engenharia Industrial
2009-07-01
A new method for direct preparation of materials for solid oxide fuel cell anode - Ni- YSZ cermets - based on mechanical alloying (MA) of the original powders is developed, allowing to admix homogeneously any component. Additive metals are selected from thermodynamic criteria, leading to compacts consolidation through sintering by activated surface (SAS). The combined process MA-SSA can reduce the sintering temperature by 300 deg C, yielding porous anodes. Densification mechanisms are discussed from quasi-isothermal sintering kinetics results. Doping with Ag, W, Cu, Mo, Nb, Ta, in descending order, promotes the densification of pellets through liquid phase sintering and evaporation of metals and oxides, which allow reducing the sintering temperature. Powders and pellets characterization by electronic microscopy and X-ray diffraction completes the result analyses. (author)
On covariant Poisson brackets in classical field theory
Forger, Michael; Salles, Mário O.
2015-10-01
How to give a natural geometric definition of a covariant Poisson bracket in classical field theory has for a long time been an open problem—as testified by the extensive literature on "multisymplectic Poisson brackets," together with the fact that all these proposals suffer from serious defects. On the other hand, the functional approach does provide a good candidate which has come to be known as the Peierls-De Witt bracket and whose construction in a geometrical setting is now well understood. Here, we show how the basic "multisymplectic Poisson bracket" already proposed in the 1970s can be derived from the Peierls-De Witt bracket, applied to a special class of functionals. This relation allows to trace back most (if not all) of the problems encountered in the past to ambiguities (the relation between differential forms on multiphase space and the functionals they define is not one-to-one) and also to the fact that this class of functionals does not form a Poisson subalgebra.
Design of an Orthodontic Torque Simulator for Measurement of Bracket Deformation
Melenka, G. W.; Nobes, D. S.; Major, P. W.; Carey, J. P.
2013-12-01
The design and testing of an orthodontic torque simulator that reproduces the effect of archwire rotation on orthodontic brackets is described. This unique device is capable of simultaneously measuring the deformation and loads applied to an orthodontic bracket due to archwire rotation. Archwire rotation is used by orthodontists to correct the inclination of teeth within the mouth. This orthodontic torque simulator will provide knowledge of the deformation and loads applied to orthodontic bracket that will aide clinicians by describing the effect of archwire rotation on brackets. This will also impact that design on new archwirebracket systems by providing an assessment of performance. Deformation of the orthodontic bracket tie wings is measured using a digital image correlation process to measure elastic and plastic deformation. The magnitude of force and moments applied to the bracket though the archwire is also measured using a six-axis load cell. Initial tests have been performed on two orthodontic brackets of varying geometry to demonstrate the measurement capability of the orthodontic torque simulator. The demonstration experiment shows that a Damon Q bracket had a final plastic deformation after a single loading of 0.022 mm while the Speed bracket deformed 0.071 mm. This indicates that the Speed bracket plastically deforms 3.2 times more than the Damon Q bracket for similar magnitude of applied moment. The demonstration experiment demonstrates that bracket geometry affect the deformation of orthodontic brackets and this difference can be detected using the orthodontic torque simulator.
Bonded Bracket Assmebly for Frameless Solar Panels
Murray, Todd [Rayce Americas, Auburn Hills, MI (United States); Jackson, Nick [Rayce Americas, Auburn Hills, MI (United States); Dupont, Luc [ARaymond Tinnerman Industries, Inc., Brunswick, OH (United States); Moser, Jeff [ARaymond Tinnerman Industries, Inc., Brunswick, OH (United States)
2013-01-30
In February 2011 the US Department of Energy announced their new Sunshot Initiative. The Sunshot goal is to reduce the total cost of solar energy systems by about 75 percent before the end of the decade. The DOE estimated that a total installed cost of $$1 per watt for photovoltaic systems would be equivalent to 5-6¢/kilowatt hour (kWh) for energy available from the grid. The DOE also estimated that to meet the $1 per watt goal, PV module costs would need to be reduced to $ .50 per watt, balance of systems costs would need to be reduced to $.40 per watt, and power electronic costs would need to reach $.10 per watt. To address the BOS balance of systems cost component of the $1 per watt goal, the DOE announced a funding opportunity called (BOS-X) Extreme Balance of System Hardware Cost Reductions. The DOE identified eight areas within the total BOS costs: 1) installation labor, 2) installation materials, 3) installation overhead and profit, 4) tracker, 5) permitting and commissioning, 6) site preparation, 7) land acquisition, 8) sales tax. The BOS-X funding announcement requested applications in four specific topics;Topic 1: Transformational Building Integrated Photovoltaic (BIPV) Modules; Topic 2: Roof and Ground Mount Innovations; Topic 3: Transformational Photovoltaic System Designs; and Topic 4: Development of New Wind Load Codes for PV Systems.The application submitted by ARaymond Tinnerman reflected the requirements listed in Topic #2, Roof and Ground Mount Innovations. The goal of topic #2 was to develop technologies that would result in the extreme reduction of material and labor costs associated with applications that require physical connections and attachments to roof and ground mount structures. The topics researched in this project included component cost reduction, labor reduction, weight reduction, wiring innovations, and alternative material utilization. The project objectives included; 1) The development of an innovative quick snap bracket assembly
Bracket states for communication protocols with coherent states
Allevi, Alessia; Olivares, Stefano; Bondani, Maria
2014-05-01
We present the generation and characterization of the class of bracket states, namely phase-sensitive mixtures of coherent states exhibiting symmetry properties in the phase-space description. A bracket state can be seen as the statistical ensemble arriving at a receiver in a typical coherent-state-based communication channel. We show that when a bracket state is mixed at a beam splitter with a local oscillator, both the emerging beams exhibit a Fano factor larger than 1 and dependent on the relative phase between the input state and the local oscillator. We discuss the possibility to exploit this dependence to monitor the phase difference for the enhancement of the performances of a simple communication scheme based on direct detection. Our experimental setup involves linear optical elements and a pair of photon-number-resolving detectors operated in the mesoscopic photon-number domain.
Basics of Ternary Algebras and their underlying Nambu Brackets
Ternary algebras amount to closing systems of antisymmetrized trinomials of operators. The Filippov conditions (FI, which are not identities) for ternary algebras are contrasted to Bremner's identities dictated by associativity of operator products, and thus analogous to Jacobi identities. Maps of the known FI-compliant ternary algebras to underlying classical Nambu brackets are constructed, which then explain this compliance: FI-compliant ternary algebras are essentially classical Nambu brackets in disguise. In some cases involving infinite algebras, we show the classical limit may be obtained by a contraction of the quantal ternary algebra, and then explicitly realized through classical Nambu brackets. We illustrate this classical-contraction method on our Virasoro-Witt ternary algebra paradigm. The content of the talk is in the two references
Bracket debonding by mid-infrared laser radiation
The purpose of the study was to determine the proper laser radiation for ceramic bracket debonding and the investigation of the tooth root temperature injury. The debonding was investigated by diode-pumped continuously running Tm:YAP and Nd:YAG lasers, and by GaAs laser diode generating radiation with the wavelengths 1.997 μm, 1.444 μm, and 0.808 μm, respectively. The possibility of brackets removal by laser radiation was investigated together with the tooth and, it specifically, root temperature rise. From the results it follows that continuously running diode pumped Tm:YAG or Nd:YAG laser generating wavelengths 1.997 μm or 1.444 μm, respectively, having the output power 1 W can be good candidates for ceramic brackets debonding
The gauge algebra of double field theory and Courant brackets
We investigate the symmetry algebra of the recently proposed field theory on a doubled torus that describes closed string modes on a torus with both momentum and winding. The gauge parameters are constrained fields on the doubled space and transform as vectors under T-duality. The gauge algebra defines a T-duality covariant bracket. For the case in which the parameters and fields are T-dual to ones that have momentum but no winding, we find the gauge transformations to all orders and show that the gauge algebra reduces to one obtained by Siegel. We show that the bracket for such restricted parameters is the Courant bracket. We explain how these algebras are realised as symmetries despite the failure of the Jacobi identity.
On the central extensions of Poisson brackets of hydrodynamic type
Poisson brackets of hydrodynamic type were introduced to construct a theory of conservation system of hydrodynamic type. They lead to the algebraic and differentially geometrical theory of local translationally invariant Lie algebras of first order, Frobenius-type algebras and Novikov algebras. One of the main ways to construct new examples of these algebras and their corresponding Poisson brackets is through the central extensions. In Balinskii A A and Novikov S P (1985 Sov. Math. Dokl. 32 228-31), there is a general theory of the central extensions. In this paper, we give a further detailed study of two (non-trivial) types of Novikov algebras which directly decide an important kind of central extension of the Poisson brackets. We find that the Novikov algebras in the case τ = 3 are in the case τ 0 and these two cases coincide in dimension ≤ 3. Moreover, they also coincide for the transitive cases in dimension 4
Structural Analysis of the Redesigned Ice/Frost Ramp Bracket
Phillips, D. R.; Dawicke, D. S.; Gentz, S. J.; Roberts, P. W.; Raju, I. S.
2007-01-01
This paper describes the interim structural analysis of a redesigned Ice/Frost Ramp bracket for the Space Shuttle External Tank (ET). The proposed redesigned bracket consists of mounts for attachment to the ET wall, supports for the electronic/instrument cables and propellant repressurization lines that run along the ET, an upper plate, a lower plate, and complex bolted connections. The eight nominal bolted connections are considered critical in the summarized structural analysis. Each bolted connection contains a bolt, a nut, four washers, and a non-metallic spacer and block that are designed for thermal insulation. A three-dimensional (3D) finite element model of the bracket is developed using solid 10-node tetrahedral elements. The loading provided by the ET Project is used in the analysis. Because of the complexities associated with accurately modeling the bolted connections in the bracket, the analysis is performed using a global/local analysis procedure. The finite element analysis of the bracket identifies one of the eight bolted connections as having high stress concentrations. A local area of the bracket surrounding this bolted connection is extracted from the global model and used as a local model. Within the local model, the various components of the bolted connection are refined, and contact is introduced along the appropriate interfaces determined by the analysts. The deformations from the global model are applied as boundary conditions to the local model. The results from the global/local analysis show that while the stresses in the bolts are well within yield, the spacers fail due to compression. The primary objective of the interim structural analysis is to show concept viability for static thermal testing. The proposed design concept would undergo continued design optimization to address the identified analytical assumptions and concept shortcomings, assuming successful thermal testing.
Gyrokinetic energy conservation and Poisson-bracket formulation
An integral expression for the gyrokinetic total energy of a magnetized plasma, with general magnetic field configuration perturbed by fully electromagnetic fields, was recently derived through the use of a gyrocenter Lie transformation. It is shown that the gyrokinetic energy is conserved by the gyrokinetic Hamiltonian flow to all orders in perturbed fields. An explicit demonstration that a gyrokinetic Hamiltonian containing quadratic nonlinearities preserves the gyrokinetic energy up to third order is given. The Poisson-bracket formulation greatly facilitates this demonstration with the help of the Jacobi identity and other properties of the Poisson brackets
Gyrokinetic energy conservation and Poisson-bracket formulation
An integral expression for the gyrokinetic total energy of a magnetized plasma with general magnetic field configuration perturbed by fully electromagnetic fields was recently derived through the use of a gyro-center Lie transformation. We show that the gyrokinetic energy is conserved by the gyrokinetic Hamiltonian flow to all orders in perturbed fields. This paper is concerned with the explicit demonstration that a gyrokinetic Hamiltonian containing quadratic nonlinearities preserves the gyrokinetic energy up to third order. The Poisson-bracket formulation greatly facilitates this demonstration with the help of the Jacobi identity and other properties of the Poisson brackets. 18 refs
On Deformations of Multidimensional Poisson Brackets of Hydrodynamic Type
Casati, Matteo
2015-04-01
The theory of Poisson vertex algebras (PVAs) (Barakat et al. in Jpn J Math 4(2):141-252, 2009) is a good framework to treat Hamiltonian partial differential equations. A PVA consists of a pair of a differential algebra and a bilinear operation called the -bracket. We extend the definition to the class of algebras endowed with commuting derivations. We call this structure a multidimensional PVA: it is a suitable setting to study Hamiltonian PDEs with d spatial dimensions. We apply this theory to the study of symmetries and deformations of the Poisson brackets of hydrodynamic type for d = 2.
Hessian matrix, specific heats, Nambu brackets, and thermodynamic geometry
Mansoori, Seyed Ali Hosseini; Fazel, Mohamadreza
2014-01-01
As an extension to our earlier work \\cite{Mirza2}, we employ the Nambu brackets to prove that the divergences of heat capacities correspond to their counterparts in thermodynamic geometry. We also obtain a simple representation for the conformal transformations that connect different thermodynamics metrics to each other. Using our bracket approach, we obtain interesting exact relations between the Hessian matrix with any number of parameters and specific heat capacities. Finally, we employ this approach to investigate some thermodynamic properties of the Meyers-Perry black holes with three spins.
Hessian matrix, specific heats, Nambu brackets, and thermodynamic geometry
Mansoori, Seyed Ali Hosseini; Mirza, Behrouz; Fazel, Mohamadreza
2015-04-01
As an extension to our earlier work [1], we employ the Nambu brackets to prove that the divergences of heat capacities correspond to their counterparts in thermodynamic geometry. We also obtain a simple representation for the conformal transformations that connect different thermodynamics metrics to each other. Using our bracket approach, we obtain interesting exact relations between the Hessian matrix with any number of parameters and specific heat capacities. Finally, we employ this approach to investigate some thermodynamic properties of the Meyers-Perry black holes with three spins.
Infinite family of polynomial functions of the Virasoro generators with vanishing Poisson brackets
An infinite family of polynominal functions of the Virasoro generators, with vanishing Poisson brackets, is constructed by exploiting the relationship between the Poisson bracket realization of the Virasoro algebra and the Korteweg-de Vries canonical structure. (orig.)
On the canonical forms of the multi-dimensional averaged brackets
Maltsev, A. Ya.
2015-01-01
We consider here special Poisson brackets given by the "averaging" of local multi-dimensional Poisson brackets in the Whitham method. For the brackets of this kind it is natural to ask about their canonical forms, which can be obtained after transformations preserving the "physical meaning" of the field variables. We show here that the averaged bracket can always be written in the canonical form after a transformation of "Hydrodynamic Type" in the case of absence of annihilators of initial br...
Kumar, Mukesh; Maheshwari, Amit; Lall, Rajeev; Navit, Pragati; Singh, Rajeshwar; Navit, S
2014-01-01
Background: Debonding of brackets commonly occurs during orthodontic treatment. Due to increase in costs replacement of a damaged bracket is not liked by the dentist. This study is done to assess the shear bond strength of recycled brackets using different methods. Materials and Methods: This study was conducted using five groups of orthodontic brackets (0.022” × 0.028”, MBT prescription) bonded on the premolars mounted in cubes. Other materials required were cubical trays, bonding material, ...
Bond efficacy of recycled orthodontic brackets: A comparative in vitro evaluation of two methods
Vikram Shetty; Yash Shekatkar; Neesu Kumbhat; G Gautam; Shalan Karbelkar; Meghna Vandekar
2015-01-01
Context: Recycling of orthodontic brackets in developing orthodontic economies is an extremely common procedure. Bonding protocols and reliability of these brackets is, however, questionable, and still the subject of research. Aims: The aim was to evaluate and compare the shear bond strength of brackets recycled with sandblasting and silicoating. Materials and Methods: Ninety extracted human premolars were bonded with 0.022” SS brackets (American Orthodontics, Sheboygan USA) and then de...
The general harmonic-oscillator brackets: compact expression, symmetries, sums and Fortran code
We present a very simple expression and a Fortran code for the fast and precise calculation of three-dimensional harmonic-oscillator transformation brackets. The complete system of symmetries for the brackets along with analytical expressions for sums containing products of two and three brackets is given
Seismic response Analyses of Hanaro in-chimney bracket structures
Lee, Jae Han; Ryu, J.S.; Cho, Y.G.; Lee, H.Y.; Kim, J.B
1999-05-01
The in-chimney bracket will be installed in the upper part of chimney, which holds the capsule extension pipes in upper one-third of length. For evaluating the effects on the capsules and related reactor structures, ANSYS finite element analysis model is developed and the dynamic characteristics are analyzed. The seismic response anlayses of in-chimney bracket and related reactor structures of HANARO under the design earthquake response spectrum loads of OBE (0.1 g) and SSE (0.2 g) are performed. The maximum horizontal displacements of the flow tubes are within the minimum half gaps between close flow tubes, it is expected that these displacement will not produce any contact between neighbor flow tubes. The stress values in main points of reactor structures and in-chimney bracket for the seismic loads are also within the ASME Code limits. It is also confirmed that the fatigue usage factor is muchless than 1.0. So, any damage on structural integrity is not expected when an in-chimney bracket is installed to upper part of the reactor chimney. (author). 12 refs., 24 tabs., 37 figs.
U matrix construction for Quantum Chromodynamics through Dirac brackets
A procedure for obtaining the U matrix using Dirac brackets, recently developed by Kiefer and Rothe, is applied for Quantum Chromodynamics. The correspondent interaction Lagrangian is the same obtained by Schwinger, Christ and Lee, using independent methods. (L.C.J.A.)
DEBONDING OF CERAMIC BRACKETS BY ER:YAG LASER
Fidan ALAKUŞ-SABUNCUOĞLU
2016-04-01
Full Text Available Purpose: The objective of the present study is to evaluate the effects of Er:YAG laser debonding of ceramic brackets on the bond strength and the amount of adhesive resin remnant. Materials and Methods: Twenty human mandibular incisors were randomly divided into two groups of 10 and polycrystalline ceramic brackets (Transcend series 6000, 3M Unitek, Monrovia, CA, USA were bonded on enamel surfaces. Group 1 was the control group in which no laser application was performed prior to the shear bond strength (SBS testing. In Group 2, Er:YAG was applied in 3W power for 6 seconds using the scanning method. The brackets were tested for SBS with an Instron universal testing machine and results were expressed in megapascals (MPa. The amount of adhesive remnant was evaluated with Adhesive Remnant Index (ARI. One-way analysis of variance and Tukey’s post-hoc tests were used for statistical analysis. Results: Mean ± standard deviation of SBS values in the control group was 13.42 ±1.23 MPa and 8.47 ±0.71 MPa in the Er:YAG group and this difference was statistically significant (p<0.05. The evaluation of ARI scores demonstrated more adhesive was left on the enamel surface with Er:YAG group. Conclusion: 3W power Er:YAG laser application with the scanning method to polycrystalline ceramic brackets demonstrated lower bond strengths and higher ARI scores during the debonding procedure.
On the Poisson bracket algebra of monodromy matrices
We present a new method to deal with the endpoint ambiguities which arise in the calculation of Poisson brackets of monodromy matrices in the principal chiral model. In contrast to previous proposals our prescription yields the Yang-Baxter equation already at the classical level. (orig.)
A simple expression for the general oscillator bracket
It is shown that there exists a simple generating function for the three-dimensional oscillator wave functions which are simultaneous eigenstates of angular momentum. This function is used to derive a new formula for the oscillator transformation brackets in the most general case of two particles with different masses moving in oscillator potentials with different frequencies. (orig.)
On covariant Poisson brackets in classical field theory
Forger, Michael [Instituto de Matemática e Estatística, Universidade de São Paulo, Caixa Postal 66281, BR–05315-970 São Paulo, SP (Brazil); Salles, Mário O. [Instituto de Matemática e Estatística, Universidade de São Paulo, Caixa Postal 66281, BR–05315-970 São Paulo, SP (Brazil); Centro de Ciências Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Campus Universitário – Lagoa Nova, BR–59078-970 Natal, RN (Brazil)
2015-10-15
How to give a natural geometric definition of a covariant Poisson bracket in classical field theory has for a long time been an open problem—as testified by the extensive literature on “multisymplectic Poisson brackets,” together with the fact that all these proposals suffer from serious defects. On the other hand, the functional approach does provide a good candidate which has come to be known as the Peierls–De Witt bracket and whose construction in a geometrical setting is now well understood. Here, we show how the basic “multisymplectic Poisson bracket” already proposed in the 1970s can be derived from the Peierls–De Witt bracket, applied to a special class of functionals. This relation allows to trace back most (if not all) of the problems encountered in the past to ambiguities (the relation between differential forms on multiphase space and the functionals they define is not one-to-one) and also to the fact that this class of functionals does not form a Poisson subalgebra.
The Moyal bracket in the coherent states framework
The star product and Moyal bracket are introduced using the coherent states corresponding to quantum systems with non-linear spectra. Two kinds of coherent state are considered. The first kind is the set of Gazeau-Klauder coherent states and the second kind are constructed following the Perelomov-Klauder approach. The particular case of the harmonic oscillator is also discussed. (author)
Structure Sense in High School Algebra: The Effect of Brackets
Hoch, Maureen; Dreyfus, Tommy
2005-01-01
This paper presents an initial attempt to define structure sense for high school algebra and to test part of this definition. A questionnaire was distributed to 92 eleventh grade students in order to identify those who use structure sense. Presence and absence of brackets was examined to see how they affect use of structure sense. The overall use…
Weak Dirac bracket construction and the superparticle covariant quantization problem
The general procedure for constructing a consistent covariant Dirac-type bracket for the models with mixed first and second class constraints is presented. The proposed scheme essentially relies upon explicit separation of the initial constraints into infinitely reducible first and second class ones (by making use of some covariant projectors). Reducibility of the second class constraints involved manifests itself in weakening some properties of the bracket as compared to the standard Dirac one. In particular, a commutation of any quantity with the second class constraints and the Jacobi identity holds on the second class constraint surface only. The procedure developed is realized for a N=1 Brink-Schwarz superparticle in arbitrary dimension and for a N=1, D=9 massive superparticle with the Wess-Zumino term. The possibility to apply the bracket for quantizing the superparticles within the framework of the recent unified algebra approach by I.A.Batalin and I.V.Tyutin (1992,1993) is examined. It is shown, in particular, that for a D=9 massive superparticle it is impossible to construct a Dirac-type bracket possessing a (strong) Jacobi identity in a full phase space. (orig.)
On covariant Poisson brackets in classical field theory
How to give a natural geometric definition of a covariant Poisson bracket in classical field theory has for a long time been an open problem—as testified by the extensive literature on “multisymplectic Poisson brackets,” together with the fact that all these proposals suffer from serious defects. On the other hand, the functional approach does provide a good candidate which has come to be known as the Peierls–De Witt bracket and whose construction in a geometrical setting is now well understood. Here, we show how the basic “multisymplectic Poisson bracket” already proposed in the 1970s can be derived from the Peierls–De Witt bracket, applied to a special class of functionals. This relation allows to trace back most (if not all) of the problems encountered in the past to ambiguities (the relation between differential forms on multiphase space and the functionals they define is not one-to-one) and also to the fact that this class of functionals does not form a Poisson subalgebra
Histological evaluation after electrothermal debonding of ceramic brackets
Vignesh Kailasam
2014-01-01
Full Text Available Aim: To evaluate the histological changes following electrothermal debonding (ETD of ceramic brackets. Materials and Methods: A total of 50 first premolar teeth from 14 patients were divided into two groups: Group I consisted of 20 teeth which served as control, and the brackets were debonded using conventional pliers. (7 teeth were extracted 24 hours after conventional debonding, 7 teeth were extracted 28 to 32 days after conventional debonding and 6 teeth were extracted 56-60 days after conventional debonding. Group II consisted of 30 teeth and the brackets were debonded using the ETD unit. (10 teeth were extracted 24 hours after ETD, 10 teeth were extracted 28 to 32 days after ETD and 10 teeth were extracted 56-60 days after ETD. Immediately after extraction, the teeth were sectioned and prepared for histological examination. Results: The pulp was normal in most samples of the control group. In group II, mild inflammation was observed in the 24 hour sample while the 28 to 32 day sample showed signs of healing. The 56-60 day sample showed that the pulp was similar to the control group in 6 out of the 10 samples. Conclusion: The ETD of ceramic brackets did not affect the pulp and the changes which were observed, were reversible in nature.
Poisson cohomology of scalar multidimensional Dubrovin-Novikov brackets
Carlet, Guido; Casati, Matteo; Shadrin, Sergey
2015-01-01
We compute the Poisson cohomology of a scalar Poisson bracket of Dubrovin-Novikov type with $D$ independent variables. We find that the second and third cohomology groups are generically non-vanishing in $D>1$. Hence, in contrast with the $D=1$ case, the deformation theory in the multivariable case is non-trivial.
On the Method of Brackets: Rules, Examples, Interpretations and Modifications
Jiu, Lin
2015-01-01
The method of brackets, consisting of a small number of heuristic rules, was created by Ivan Gonzalez for the evaluation of definite integrals appearing in the resolution of Feynman diagrams. The current work verifies each step of this method, proves the independence on different representations of the integrand, and also modifies the rule by further considering analytic continuation.
Multiple Bracket Function, Stirling Number, and Lah Number Identities
Coskun, Hasan
2012-01-01
The author has constructed multiple analogues of several families of combinatorial numbers in a recent article, including the bracket symbol, and the Stirling numbers of the first and second kind. In the present paper, a multiple analogue of another sequence, the Lah numbers, is developed, and certain associated identities and significant properties of all these sequences are constructed.
Evaluation of Perceived Acceptability, Beauty and Value of Different Orthodontic Brackets
Moshkelgosha V
2015-03-01
Full Text Available Statement of Problem: Although different types of aesthetic brackets are introduced to orthodontic profession to reduce the complaints about the metallic braces, little studies have been done to assess patient's views regarding the attractiveness and acceptance of such brackets. Objectives: The goal of this study was to evaluate the perceived acceptability, beauty and value of different orthodontic brackets. Materials and Methods: In a cross-sectional study, three groups of subjects consisting of dental school clinic patients, specialty clinic patients, and art students were interviewed. Sample size was decided 116 in each group. The photographic images of six types of brackets which were placed in an adult mouth were shown to the subjects and they were asked to answer the questions that evaluate attractiveness by visual analog scale (VAS, acceptability of different brackets, and willingness to pay (WTP for an aesthetic bracket in comparison to a regular bracket. Reliability was measured by giving questionnaires to 20 respondents by a two-week interval. VAS rating was compared by ANOVA. Mann U Whitney and Chi-square tests were used to compare the acceptability between groups when necessary. Results: The reliability measurement results performed by ICC were 0.86 for attractiveness, 0.6 for acceptability, and 0.93 for WTP questions. Lingual brackets had the highest attractiveness rating while metal brackets were considered the lowest aesthetic appliance by all groups of the study. The acceptability of ceramic bracket was highest in all groups. While most appliances evaluated had average acceptability, the large metallic brackets were rated very low. WTP for aesthetic braces was higher in art students than other groups. Conclusions: Lingual brackets were the most attractive but had very low acceptability rate. Small metal brackets had a good acceptability rate. Large metal brackets were the least attractive and had the lowest acceptability. Parents
Bond strength of disinfected metal and ceramic brackets: an in vitro study.
Speer, Cornelia; Zimny, Dorothee; Hopfenmueller, Werner; Holtgrave, Eva Andrea
2005-09-01
The aim of this in vitro investigation was to test whether disinfecting with Chlorhexamed fluid had an influence on the shear bond strength of metal and ceramic orthodontic brackets. Metal and ceramic brackets were fixed by the composite adhesives Transbond XT (light curing) and Concise (chemical curing) to 224 bovine permanent mandibular incisors. Bovine teeth were divided into eight groups of 28 each as group 1: metal bracket/Transbond XT, group 2: disinfected metal bracket/Transbond XT, group 3: metal bracket/Concise, group 4: disinfected metal bracket/Concise, group 5: ceramic bracket/Transbond XT, group 6: disinfected ceramic bracket/Transbond XT, group 7: ceramic bracket/Concise, and group 8: disinfected ceramic bracket/Concise. Adhesive bonding was done according to the manufacturers' instructions. As shown by group comparison (Kruskal-Wallis test, univariate analysis of variance, P < .001), the disinfection of metal brackets had no statistically relevant influence on shear bond strength (P = .454). However, disinfecting ceramic brackets with either adhesive led to a significant reduction in shear bond strength compared with the untreated ceramic bracket group (P < .001). The Fisher's exact test of the Adhesive Remnant Index (ARI) scores showed a significant difference within the metal group bonded with different adhesives (P = .0003). The ARI scores 1 and 2 were not reached by the ceramic bracket groups. The disinfection of the ceramic brackets is a suitable procedure for clinical use because the measured shear bond strength values were higher than 6-8 MPa required in orthodontics. PMID:16279832
Smita B. Patil; M.B. Halkati; Amit Shaikh; Srinivas Ambarkar; Shakeel Galgali
2014-01-01
Background: Self-Ligating brackets were originally designed with the intention to reduce the time needed to change wires compared with the use of wire ligatures. However, the advent of elastomeric ligatures meant that this perceived advantage was diminished. Objective: To compare aligning efficiency, rate of retraction and torque expression of Self Ligating bracket (SLB) system with Conventional Pre adjusted Edgewise bracket (CLB) system. Materials and Methods: Twelve patients were selected a...
Galvanic corrosion between orthodontic wires and brackets in fluoride mouthwashes.
Schiff, Nicolas; Boinet, Mickaël; Morgon, Laurent; Lissac, Michèle; Dalard, Francis; Grosgogeat, Brigitte
2006-06-01
The aim of this investigation was to determine the influence of fluoride in certain mouthwashes on the risk of corrosion through galvanic coupling of orthodontic wires and brackets. Two titanium alloy wires, nickel-titanium (NiTi) and copper-nickel-titanium (CuNiTi), and the three most commonly used brackets, titanium (Ti), iron-chromium-nickel (FeCrNi) and cobalt-chromium (CoCr), were tested in a reference solution of Fusayama-Meyer artificial saliva and in two commercially available fluoride (250 ppm) mouthwashes, Elmex and Meridol. Corrosion resistance was assessed by inductively coupled plasma-atomic emission spectrometry (ICP-MS), analysis of released metal ions, and a scanning electron microscope (SEM) study of the metal surfaces after immersion of different wire-bracket pairs in the test solutions. The study was completed by an electrochemical analysis. Meridol mouthwash, which contains stannous fluoride, was the solution in which the NiTi wires coupled with the different brackets showed the highest corrosion risk, while in Elmex mouthwash, which contains sodium fluoride, the CuNiTi wires presented the highest corrosion risk. Such corrosion has two consequences: deterioration in mechanical performance of the wire-bracket system, which would negatively affect the final aesthetic result, and the risk of local allergic reactions caused by released Ni ions. The results suggest that mouthwashes should be prescribed according to the orthodontic materials used. A new type of mouthwash for use during orthodontic therapy could be an interesting development in this field. PMID:16428255
Andrea Scribante
2013-01-01
Full Text Available Objective. The aim of this study was to compare the shear bond strength (SBS and adhesive remnant index (ARI scores of no-primer adhesives tested with two different bracket bases. Materials and Methods. 120 bovine permanent mandibular incisors were divided into 6 groups of 20 specimens. Two brackets (ODP with different bracket bases (anchor pylons and 80-gauge mesh were bonded to the teeth using a conventional adhesive (Transbond XT and two different no-primer adhesive (Ortho Cem; Heliosit systems. Groups were tested using an instron universal testing machine. SBS values were recorded. ARI scores were measured. SEM microphotographs were taken to evaluate the pattern of bracket bases. Statistical analysis was performed. ANOVA and Tukey tests were carried out for SBS values, whereas a chi-squared test was applied for ARI scores. Results. Highest bond strength values were reported with Transbond XT (with both pad designs, Ortho Cem bonded on anchor pylons and Heliosit on 80-gauge mesh. A higher frequency of ARI score of “3” was reported for Transbond XT groups. Other groups showed a higher frequency of ARI score “2” and “1.” Conclusion. Transbond XT showed the highest shear bond strength values with both pad designs.
Adherence of Streptococcus mutans and Candida albicans to different bracket materials
Shrinivaasan Nambi Rammohan
2012-01-01
Full Text Available Objective: To quantify the adherence of Streptococcus mutans and Candida albicans on brackets made of stainless steel, plastic, ceramic, titanium, and gold, and to evaluate the various sites of adherence of these microorganisms with scanning electron microscopy (SEM. Materials and Methods: Brackets made of stainless steel, plastic, ceramic, titanium, and gold were used. The adherence of S. mutans and C. albicans were studied. The brackets were placed in flat-bottomed vials containing basal medium with 20% sucrose added; the flasks were inoculated with each of the microbial suspensions. The samples were incubated at 37°C for 48 h, after which the brackets were removed. The cells adhering to the glass were counted and the brackets were studied with SEM. Results: When evaluated together, the adherence of S. mutans and C. albicans was increased in the ceramic bracket group. When evaluated separately, metallic brackets had increased number of colony-forming units (CFUs of S. mutans and the use of titanium brackets increased the CFUs of C. albicans. SEM demonstrated that the adherence of S. mutans and C. albicans together varied according to the bracket materials, with ceramic having the greatest and stainless steel having the least adherence. Conclusions: Oral hygiene may be of greater concern with esthetic brackets since this study shows that microbial adhesion is greater with these brackets.
A comparison of self-ligating and conventional orthodontic bracket systems.
Read-Ward, G E; Jones, S P; Davies, E H
1997-11-01
This ex-vivo study compared the static frictional resistance of three self-ligating brackets with a conventional steel-ligated Ultratrimm bracket. The effects of archwire size (0.020, 0.019 x 0.025 and 0.021 x 0.025-inch), bracket/archwire angulation (0, 5 and 10 degrees) and the presence of unstimulated human saliva were investigated. The study demonstrated that both increases in wire size and bracket/archwire angulation resulted in increased static frictional resistance for all bracket types tested, with the presence of saliva having an inconsistent effect. Mobil-Lock Variable-Slot had the least friction for all wires for 0 degree angulation. However, with the introduction of angulation, the values were comparable to those of the other brackets. Activa brackets had the second lowest frictional resistance, although high values were found with 0.019 x 0.025-inch wires. SPEED brackets demonstrated low forces with round wires, although with rectangular wires or in the presence of angulation, friction was greatly increased. Ultratrimm brackets produced large individual variation, confirming the difficulty in standardizing ligation force, although under certain conditions, significantly larger frictional forces were observed. In conclusion, self-ligating brackets showed reduced frictional resistance in comparison to steel ligated brackets only under certain conditions. PMID:9459030
Frictional and mechanical properties of diamond-like carbon-coated orthodontic brackets.
Muguruma, Takeshi; Iijima, Masahiro; Brantley, William A; Nakagaki, Susumu; Endo, Kazuhiko; Mizoguchi, Itaru
2013-04-01
This study investigated the effects of a diamond-like carbon (DLC) coating on frictional and mechanical properties of orthodontic brackets. DLC films were deposited on stainless steel brackets using the plasma-based ion implantation/deposition (PBIID) method under two different atmospheric conditions. As-received metal brackets served as the control. Two sizes of stainless steel archwires, 0.018 inch diameter and 0.017 × 0.025 inch cross-section dimensions, were used for measuring static and kinetic friction by drawing the archwires through the bracket slots, using a mechanical testing machine (n = 10). The DLC-coated brackets were observed with a scanning electron microscope (SEM). Values of hardness and elastic modulus were obtained by nanoindentation testing (n = 10). Friction forces were compared by one-way analysis of variance and the Scheffé test. The hardness and elastic modulus of the brackets were compared using Kruskal-Wallis and Mann-Whitney U-tests. SEM photomicrographs showed DLC layers on the bracket surfaces with thickness of approximately 5-7 μm. DLC-coated brackets deposited under condition 2 showed significantly less static frictional force for the stainless steel wire with 0.017 × 0.025 inch cross-section dimensions than as-received brackets and DLC-coated brackets deposited under condition 1, although both DLC-coated brackets showed significantly less kinetic frictional force than as-received brackets. The hardness of the DLC layers was much higher than that of the as-received bracket surfaces. In conclusion, the surfaces of metal brackets can be successfully modified by the PBIID method to create a DLC layer, and the DLC-coating process significantly reduces frictional forces. PMID:21934113
José Rino Neto
2013-02-01
Full Text Available OBJECTIVE: To compare hysteresis, activation and deactivation forces produced by first-order deformation of Contour 0.014-in NiTi wire (Aditek, Brazil in four brands of self-ligating brackets: Damon MX, Easy Clip, Smart Clip and In-Ovation. METHODS: Activation and deactivation forces were measured in an Instron universal tensile machine at 3 mm/minute speed to a total displacement of 4 mm. Tests were repeated eight times for each bracket/wire combination. Statistical analysis comprised ANOVA and Tukey's multiple comparisons test. RESULTS: Using a 4-mm deformation, mean activation forces increased in the following order: Damon = 222 gf, Easy Clip = 228 gf, In-Ovation = 240 gf and Smart Clip = 306 gf. The same order was observed for mean hysteresis values, i.e., 128 gf, 140 gf, 150 gf and 206 gf, respectively. The respective values of deactivation forces for the Damon, Easy Clip, In-Ovation and Smart Clip brackets were 94 gf, 88 gf, 90 gf and 100 gf. CONCLUSIONS: Brackets with higher activation forces were accompanied by higher hysteresis values, which resulted in clinically similar deactivation forces, regardless of the type of self-ligating brackets used.OBJETIVO: comparar as forças de ativação, desativação e histerese produzidas por deformação de primeira ordem do fio superelástico Contour NiTi 0,014" (Aditek® em quatro modelos de braquetes autoligáveis: Damon MX, Easy Clip, Smart Clip e In-Ovation. MÉTODOS: as forças de ativação e desativação foram medidas em máquina universal de tração Instron com velocidade de 3mm/minuto e deslocamento de 4mm. Em cada combinação braquete/fio foram executadas oito repetições. A análise estatística empregou ANOVA e o Teste de Comparações Múltiplas de Tukey. RESULTADOS: com 4mm de deformação, as forças médias de ativação foram, em ordem crescente, Damon = 222gf, Easy Clip = 228gf, In-Ovation = 240gf e Smart-Clip = 306gf; a mesma ordem foi observada nas histereses médias, cujos
A polynomial bracket for the Dubrovin--Zhang hierarchies
Buryak, A; Shadrin, S
2010-01-01
We define a hierarchy of Hamiltonian PDEs associated to an arbitrary tau-function in the semi-simple orbit of the Givental group action on genus expansions of Frobenius manifolds. We prove that the equations, the Hamiltonians, and the bracket are weighted-homogeneous polynomials in the derivatives of the dependent variables with respect to the space variable. In the particular case of a conformal (homogeneous) Frobenius structure, our hierarchy coincides with the Dubrovin-Zhang hierarchy that is canonically associated to the underlying Frobenius structure. Therefore, our approach allows to prove the polynomiality of the equations, Hamiltonians and one of the Poisson brackets of these hierarchies, as conjectured by Dubrovin and Zhang.
Algebric generalization of symmetry Dirac bracket. Application to field theory
The A set of observable of a physical system with finite e infinite number of degrees of freedom and submitted to certain constraint conditions, is considered. Using jordan algebra structure on A in relation to bymmetric Poisson bracket obtained by Droz-Vincent, a jordan product is obtained on the A/I quocient set with regard to I ideal generated by constraints of second class. It is shown that this product on A/I corresponds to symmetric Dirac bracket. The developed formulation is applied to a system corresponding to harmonic oscillators, non relativistic field, Rarita-Schwinger field and the possibility of its utilization in fermionic string theories is discussed. (M.C.K.)
Derivation of the Hall and Extended Magnetohydrodynamics Brackets
D'Avignon, E C; Lingam, M
2015-01-01
There are several plasma models intermediate in complexity between ideal magnetohydrodynamics (MHD) and two-fluid theory, with Hall and Extended MHD being two important examples. In this paper we investigate several aspects of these theories, with the ultimate goal of deriving the noncanonical Poisson brackets used in their Hamiltonian formulations. We present fully Lagrangian actions for each, as opposed to the fully Eulerian, or mixed Eulerian-Lagrangian, actions that have appeared previously. As an important step in this process we exhibit each theory's two advected fluxes (in analogy to ideal MHD's advected magnetic flux), discovering also that with the correct choice of gauge they have corresponding Lie-dragged potentials resembling the electromagnetic vector potential, and associated conserved helicities. Finally, using the Euler-Lagrange map, we show how to derive the noncanonical Eulerian brackets from canonical Lagrangian ones.
New formulation of M-theory and Nambu bracket
M-theory is expected to be a candidate which lies behind various superstring theories and has the simplest and the fundamental structure. Recently, there was a rapid development on the internal symmetry of multiple M2-branes and its symmetry turned out to be closely related to Nambu-bracket, which has been known for long time as a mysterious dynamical system. It describes strongly coupled system in 2+1 dimensions through the duality with gravity. (author)
The Geometry of Brackets and the Area Principle
Apel, Susanne
2014-01-01
We treat the interplay of geometry and bracket algebra. The new structure of Gamma-Cycles emerges as the crucial basic building block when interpreting biquadratic proofs via the area principle. Their structure is analyzed and new incidence theorems can be derived. Cayley factorization expresses special position of points via a ruler construction. It is known that this is possible only up to non-degeneracy conditions. The thesis reduces their degree by a factor of ten compared to known res...
Evaluation of bond strength of orthodontic brackets without enamel etching
Boruziniat, Alireza; Khazaei, Yegane; Motaghi, Shiva; Moghaddas, Mohmmadjavad
2015-01-01
Background To compare the shear bond strength of brackets with and without enamel etching. Material and Methods In this study, 60 sound premolars were randomly divided into four different groups: 1- TXE group: Enamel etching+Transbond XT adhesive+ Transbond XT composite. 2- TXS group: Transbond plus self-etch adhesive+ Transbond XT composite. 3- PQ1E group: Enamel etching+ PQ1 adhesive+ Transbond XT composite. 4- PQ1 group: PQ1 adhesive+ Transbond XT composite. The shear bond strengths of bra...
Maslov indices, Poisson brackets, and singular differential forms
Esterlis, Ilya; Haggard, Hal M.; Hedeman, Austin; Littlejohn, Robert G.
2014-01-01
Maslov indices are integers that appear in semiclassical wave functions and quantization conditions. They are often notoriously difficult to compute. We present methods of computing the Maslov index that rely only on typically elementary Poisson brackets and simple linear algebra. We also present a singular differential form, whose integral along a curve gives the Maslov index of that curve. The form is closed but not exact, and transforms by an exact differential under canonical transformati...
Green-Schwarz mechanism and $\\alpha'$-deformed Courant brackets
Hohm, Olaf
2014-01-01
We establish that the unusual two-form gauge transformations needed in the Green-Schwarz anomaly cancellation mechanism fit naturally into an $\\alpha'$-deformed generalized geometry. The algebra of gauge transformations is a consistent deformation of the Courant bracket and features a nontrivial modification of the diffeomorphism group. This extension of generalized geometry emerged from a `doubled $\\alpha'$-geometry', which provides a construction of exactly gauge and T-duality invariant $\\alpha'$ corrections to the effective action.
Green-Schwarz mechanism and α'-deformed Courant brackets
Hohm, Olaf; Zwiebach, Barton
2015-01-01
We establish that the unusual two-form gauge transformations needed in the Green-Schwarz anomaly cancellation mechanism fit naturally into an α'-deformed generalized geometry. The algebra of gauge transformations is a consistent deformation of the Courant bracket and features a nontrivial modification of the diffeomorphism group. This extension of generalized geometry emerged from a `doubled α'-geometry', which provides a construction of exactly gauge and T-duality invariant α' corrections to the effective action.
Derivation of the Hall and Extended Magnetohydrodynamics Brackets
D'Avignon, E. C.; Morrison, P. J.; Lingam, M.
2015-01-01
There are several plasma models intermediate in complexity between ideal magnetohydrodynamics (MHD) and two-fluid theory, with Hall and Extended MHD being two important examples. In this paper we investigate several aspects of these theories, with the ultimate goal of deriving the noncanonical Poisson brackets used in their Hamiltonian formulations. We present fully Lagrangian actions for each, as opposed to the fully Eulerian, or mixed Eulerian-Lagrangian, actions that have appeared previous...
Orthodontic bracket bonding to glazed full-contour zirconia
Kwak, Ji-Young; Jung, Hyo-Kyung; Choi, Il-Kyung
2016-01-01
Objectives This study evaluated the effects of different surface conditioning methods on the bond strength of orthodontic brackets to glazed full-zirconia surfaces. Materials and Methods Glazed zirconia (except for the control, Zirkonzahn Prettau) disc surfaces were pre-treated: PO (control), polishing; BR, bur roughening; PP, cleaning with a prophy cup and pumice; HF, hydrofluoric acid etching; AA, air abrasion with aluminum oxide; CJ, CoJet-Sand. The surfaces were examined using profilometry, scanning electron microscopy, and electron dispersive spectroscopy. A zirconia primer (Z-Prime Plus, Z) or a silane primer (Monobond-S, S) was then applied to the surfaces, yielding 7 groups (PO-Z, BR-Z, PP-S, HF-S, AA-S, AA-Z, and CJ-S). Metal bracket-bonded specimens were stored in water for 24 hr at 37℃, and thermocycled for 1,000 cycles. Their bond strengths were measured using the wire loop method (n = 10). Results Except for BR, the surface pre-treatments failed to expose the zirconia substructure. A significant difference in bond strengths was found between AA-Z (4.60 ± 1.08 MPa) and all other groups (13.38 ± 2.57 - 15.78 ± 2.39 MPa, p < 0.05). For AA-Z, most of the adhesive remained on the bracket. Conclusions For bracket bonding to glazed zirconia, a simple application of silane to the cleaned surface is recommended. A zirconia primer should be used only when the zirconia substructure is definitely exposed. PMID:27200278
Woods, David Keith
The purpose of this study was to analyze the resistance to sliding of coated rectangular fiber reinforced composite archwires using various brackets systems and second-order bracket angulations. Resistance to sliding was investigated for eight bracket systems: six self-ligating brackets (four passive and two passive-active) and two conventional brackets. A rectangular fiber reinforced composite archwire of 0.019 x 0.025-in dimension from BiomersRTM SimpliClear was drawn through a three-bracket model system at ten millimeters per minute for 2.5 millimeters. For each bracket, the resistance to sliding was measured at four bracket angulations (0°, 2.5°, 5°, and 10°) in a dry state at room temperature. The fiber reinforced composite archwire produced the lowest sliding resistance with the passive self-ligating bracket system (Damon DQ) at each bracket angulation tested. Overall, self-ligating bracket systems generated lower sliding resistance than conventionally ligated systems, and one passive/active self-ligating bracket system (In-Ovation-R). There was a significant increase in resistance to sliding as bracket angulation increased for all bracket systems tested. Microscopic analysis revealed increased perforation of the archwire coating material as bracket angulations were increased. Our findings show that the rectangular fiber reinforced composite archwire may be acceptable for sliding mechanics during the intermediate stages of orthodontic tooth movement, however more long-term studies are needed.
Applicative Characteristics of a New Zirconia Bracket with Multiple Slots
Maki, Koutaro; Futaki, Katsuyoshi; Tanabe, Satoru; Takahashi, Mariko; Ichikawa, Yuta; Yamaguchi, Tetsutaro
2016-01-01
We have developed a new orthodontic bracket with three slots with lubricative properties on the working surfaces and proposed a new orthodontic treatment system employing 0.012−0.014-inch Ni-Ti arch wires. We recruited 54 patients, of which 27 received treatment with the new zirconia bracket with multiple slots system (M group), and the others received treatment with standard edge-wise appliances (control group [C group]). We compared the (1) tooth movement rate at the early stage of leveling; (2) changes in the dental arch morphology before and after leveling; and (3) pain caused by orthodontic treatment. Student's t-test was used in all assessments. The tooth movement rate in the maxillomandibular dentition was higher in the M group. The basal arch width, anterior length, and the intercanine width in the maxillary dentition were not significantly different in the two groups; however, the intercanine width in the mandibular dentition was higher in the C group. In assessments of treatment-related pain, the visual analogue pain score was 56.0 mm and 22.6 mm in the C and M groups, respectively. A new zirconia bracket with multiple slots system provided better outcomes with respect to tooth movement rate, treatment period, and postoperative pain, thus indicating its effectiveness over conventional orthodontic systems. PMID:27212948
Actual versus theoretical torsional play in conventional and self-ligating bracket systems
Dalstra, Michel; Eriksen, Henrik; Bergamini, Chiara; Melsen, Birte
2015-01-01
Abstract Objective: The aim of this study was to assess the amount of torsional play in 32 commercially available self-ligating and conventional 0·018-inch and 0·022-inch bracket systems in relation to 0·017×0·022-inch and 0·019×0·025-inch stainless steel wires, respectively, and compare the...... results with the theoretical amount of play for the given bracket/wire combinations. Methods: Torque moments were measured in a mechanical force testing system by twisting straight pieces of stainless steel wire seated in the bracket slot in increments of 0·5° until a full torsional expression was...... registered. Five upper central incisor brackets from each of the 32 different bracket systems were selected for the study. Results: The result from the laboratory testing clearly showed that wire/slot play was larger than anticipated from the nominal values, especially regarding the 0·022-inch brackets and...
Kim, Tae-Won; Lim, Sang-Sub; Seok, Ho-Hyun; Kang, Chung-Gil
2013-09-01
Brackets in ships and offshore structures are added structures that can endure stress concentrations. In this study, a concurrent engineering solution was proposed, and a high strength low carbon cast steel alloy applicable to offshore structures was designed and developed. The yield strength and ultimate tensile strength of the designed steel were 480 and 600 MPa, respectively. The carbon equivalent of the steel was 0.446 with a weld crack susceptibility index of 0.219. The optimal structural design of the brackets for offshore structures was evaluated using ANSYS commercial software. The possibility of replacing an assembly of conventional built-up brackets with a single casting bulb bracket was verified. The casting process was simulated using MAGMAsoft commercial software, and a casting fabrication process was designed. For the proposed bulb bracket, it was possible to reduce the size and weight by approximately 30% and 50%, respectively, compared to the conventional type of bracket.
Finite Element Analysis Design of a Split Rotor Bracket for a Bulb Turbine Generator
Luo, Yongyao; Wang, Zhengwei; Chen, Liangnian; Wu, Jinshui
2013-01-01
The rotor bracket is a key component of the generator rotor with cracks in the rotor bracket leading to rubbing between the rotor and stator, which threatens safe operation of the unit. The rotor rim is so complicated that the equivalent radial stiffness of rim was determined by numerical simulation other than engineering experience. A comprehensive numerical method including finite element analyses and the contact method for multibody dynamics has been used to design the split rotor bracket....
Optimal enamel conditioning strategy for rebonding orthodontic brackets: a laboratory study
Zhang, Qi-Feng; Yao, Hua; Li, Zhi-Yong; Jin, Li; Wang, Hui-Ming
2014-01-01
Objective: To compare the conventional etching and primer method (CEP) and the self-etching primer method (SEP) in rebonding brackets. Methods: Forty human maxillary second premolars extracted for orthodontic purpose were randomly divided into 4 equal groups. Group 1 and Group 2 were bonded using the CEP method; Group 3 and Group 4 using the SEP method. All the brackets were debonded and 40 new brackets were rebonded with four different protocols after surface cleaning: Group 1: CEP + adhesiv...
Jithesh, C.; Venkataramana, V.; Penumatsa, Narendravarma; Reddy, S N.; Poornima, K. Y.; Rajasigamani, K.
2015-01-01
Objectives: To determine and compare the potential difference of nickel release from three different orthodontic brackets, in different artificial pH, in different time intervals. Materials and Methods: Twenty-seven samples of three different orthodontic brackets were selected and grouped as 1, 2, and 3. Each group was divided into three subgroups depending on the type of orthodontic brackets, salivary pH and the time interval. The Nickel release from each subgroup were analyzed by using indu...
Arici, Nursel; Akdeniz, Berat Serdar; Arici, Selim
2015-01-01
Objective The coefficients of friction (COFs) of aesthetic ceramic and stainless steel brackets used in conjunction with stainless steel archwires were investigated using a modified linear tribometer and special computer software, and the effects of the bracket slot size (0.018 inches [in] or 0.022 in) and materials (ceramic or metal) on the COF were determined. Methods Four types of ceramic (one with a stainless steel slot) and one conventional stainless steel bracket were tested with two ty...
What is the best method for debonding metallic brackets from the patient’s perspective?
PITHON, Matheus Melo; Santos Fonseca Figueiredo, Daniel; Oliveira, Dauro Douglas; Coqueiro, Raildo da Silva
2015-01-01
Background The aim of this clinical investigation was to compare the level of discomfort reported by patients during the removal of orthodontic metallic brackets performed with four different debonding instruments. Methods The sample examined in this split-mouth study comprised a total of 70 patients (840 teeth). Four different methods of bracket removal were used: lift-off debonding instrument (LODI), straight cutter plier (SC), how plier (HP), and bracket removal plier (BRP). Prior to debon...
Pulpal Thermal Changes following Er-YAG Laser Debonding of Ceramic Brackets
Didem Nalbantgil; Murat Tozlu; Mehmet Oguz Oztoprak
2014-01-01
Lasers are effective in debonding ceramic brackets. Unfortunately, while reducing the adhesive bond strength, lasers are also reported to increase pulpal temperature. The aim of this study was to evaluate the shear bond strengths and temperature increase levels after debonding ceramic brackets using an Er-YAG laser with or without water-cooling. Sixty polycrystalline upper premolar ceramic brackets were placed on the labial surface of sixty human premolar teeth which were randomly divided int...
In vitro study of color stability of polycrystalline and monocrystalline ceramic brackets
de Oliveira, Cibele Braga; Maia, Luiz Guilherme Martins; Santos-Pinto, Ary; Gandini Júnior, Luiz Gonzaga
2014-01-01
Objective The aim of this in vitro study was to analyze color stability of monocrystalline and polycrystalline ceramic brackets after immersion in dye solutions. Methods Seven ceramic brackets of four commercial brands were tested: Two monocrystalline and two polycrystalline. The brackets were immersed in four dye solutions (coffee, red wine, Coke and black tea) and in artificial saliva for the following times: 24 hours, 7, 14 and 21 days, respectively. Color changes were measured by a spectr...
Effect of multiple debonding sequences on shear bond strength of new stainless steel brackets
Eslamian, Ladan; Borzabadi-Farahani, Ali; Tavakol, Pegah; Tavakol, Ali; Amini, Nazila; Lynch, Edward
2015-01-01
Objectives: This in-vitro study aimed at evaluating the effect of three debonding sequences on the shear bond strength (SBS) of new stainless steel (SS) brackets. Materials and Methods: Stainless steel twin brackets (0.022-inch, American Orthodontics, Sheboygan, WI, USA) were bonded with light cure adhesive (Transbond XT, 3M Unitek, St. Paul, MN, USA) to 80 newly extracted human premolars after acid etching with 37% phosphoric acid (30 s). Brackets were debonded with a universal testing machi...
Dirac's and Generalized Faddeev-Jackiw brackets for Einstein's theory in G $\\rightarrow 0$ limit
Escalante, Alberto; Rodríguez-Tzompantzi, Omar
2015-01-01
In this paper the Dirac and Faddeev-Jackiw formulation for Einstein's theory in the $G \\rightarrow 0$ limit is performed; the fundamental Dirac's and Faddeev-Jackiw brackets for the theory are obtained. First, the Dirac brackets are constructed by eliminating the second class constraints remaining the first class ones, then we fix the gauge and we convert the first class constraints into second class constraints and the new fundamental Dirac's brackets are computed. Alternatively, we reproduc...
Evaluation of Perceived Acceptability, Beauty and Value of Different Orthodontic Brackets
Moshkelgosha V; Salahi M; Rostami Sh
2015-01-01
Statement of Problem: Although different types of aesthetic brackets are introduced to orthodontic profession to reduce the complaints about the metallic braces, little studies have been done to assess patient's views regarding the attractiveness and acceptance of such brackets. Objectives: The goal of this study was to evaluate the perceived acceptability, beauty and value of different orthodontic brackets. Materials and Methods: In a cross-sectional study, three groups of ...
Dalili Kajan, Zahra; Khademi, Jalil; Alizadeh, Ahmad; Babaei Hemmaty, Yasamin; Atrkar Roushan, Zahra
2015-01-01
Purpose This study was performed to compare the metal artifacts from common metal orthodontic brackets in magnetic resonance imaging. Materials and Methods A dry mandible with 12 intact premolars was prepared, and was scanned ten times with various types of brackets: American, 3M, Dentaurum, and Masel orthodontic brackets were used, together with either stainless steel (SS) or nickel titanium (NiTi) wires. Subsequently, three different sequences of coronal and axial images were obtained: spin...
On the equivalence of different presentations of Turner's bracket abstraction algorithm
Czajka, Łukasz
2015-01-01
Turner's bracket abstraction algorithm is perhaps the most well-known improvement on simple bracket abstraction algorithms. It is also one of the most studied bracket abstraction algorithms. The definition of the algorithm in Turner's original paper is slightly ambiguous and it has been subject to different interpretations. It has been erroneously claimed in some papers that certain formulations of Turner's algorithm are equivalent. In this note we clarify the relationship between various pre...
The effect of air abrasion on the retention of metallic brackets bonded to fluorosed enamel surface
S Suma; Anita, G; B R Chandra Shekar; Amitabh Kallury
2012-01-01
Background: Bonding brackets to fluorosed enamel remains a clinical challenge and bracket failure at the compromised enamel interface is common. Objective: To check the effect of air abrasion on the retention of metallic brackets bonded to fluorosed enamel surface. Materials and Methods: Sixty freshly extracted human premolar teeth having moderate to severe dental fluorosis as per Dean′s criteria were collected and divided into three groups of 20 each. The groups were treated as follo...
Dirac's and generalized Faddeev-Jackiw brackets for Einstein's theory in the G → 0 limit
Escalante, Alberto; Tzompantzi, Omar Rodríguez
2016-01-01
In this paper the Dirac and Faddeev-Jackiw formulation for Einstein's theory in the G → 0 limit is performed; the fundamental Dirac's and Faddeev-Jackiw brackets for the theory are obtained. First, the Dirac brackets are constructed by eliminating the second class constraints remaining the first class ones, then we fix the gauge and we convert the first class constraints into second class constraints and the new fundamental Dirac's brackets are computed. Alternatively, we reproduce all relevant Dirac's results by means of the symplectic method. We identify the Faddeev-Jackiw constraints and we prove that the Dirac and the Faddeev-Jackiw brackets coincide to each other.
Dirac's and Generalized Faddeev-Jackiw brackets for Einstein's theory in G $\\rightarrow 0$ limit
Escalante, Alberto
2015-01-01
In this paper the Dirac and Faddeev-Jackiw formulation for Einstein's theory in $G \\rightarrow 0$ limit is performed; the fundamental Dirac's and Faddeev-Jackiw brackets for the theory are obtained. First, the Dirac brackets are constructed by eliminating the second class constraints remaining the first class ones, then we fix the gauge and we convert the first class constraints in second class constraints and the new fundamental Dirac's brackets are computed. Alternatively, we reproduce all relevant Dirac's results by means of the symplectic method. We identify the Faddeev-Jackiw constraints and we prove that the Dirac and the Faddeev-Jackiw brackets coincide to each other.
A comparative study of conventional ligation and self-ligation bracket systems.
Shivapuja, P K; Berger, J
1994-11-01
The increased use of self-ligating bracket systems frequently raises the question of how they compare with conventional ligation systems. An in vitro and clinical investigation was undertaken to evaluate and compare these distinctly different groups, by using five different brackets. The Activa ("A" Company, Johnson & Johnson, San Diego, Calif.), Edgelok (Ormco, Glendora, Calif.), and SPEED (Strite Industries Ltd., Cambridge, Ontario) self-ligating bracket systems displayed a significantly lower level of frictional resistance, dramatically less chairtime for arch wire removal and insertion, and promoted improved infection control, when compared with polyurethane elastomeric and stainless steel tie wire ligation for ceramic and metal twin brackets. PMID:7977187
Kumar, Sujeet; Hamsa P.R, Rani; Ahmed, Sameer; Prasanthma; Bhatnagar, Apoorva; Sidhu, Manreet; Shetty, Pramod
2014-01-01
AIM: The aim of this study was to compare frictional resistance which was produced between conventional brackets (0.022 slot Otho-Organiser) and self ligating brackets (active Forestadent and passive Damon III) by using various arch wire combinations (0.016 Niti, 0.018 Niti, 0.017 x 0.025 SS and 0.019 x 0.025 SS). Methods: An experimental model which consisted of 5 aligned stainless steel 0.022-in brackets was used to assess frictional forces which were produced by SLBs (self ligating brackets) and CELs (conventional elastomeric ligatures) with use of 0.016 nickel titanium, 0.018 nickel titanium, 0.017 X 0.025”stainless steel and 0.019 X 0.025”stainless steel wires. Statistical analysis: One way ANOVA test was used to study the effect of the bracket type, wire alloy and section on frictional resistance test . Results: Conventional brackets produced highest levels of friction for all bracket/archwire combinations. Both Damon III and Forestadent brackets were found to produce significantly lower levels of friction when they were compared with elastomerically tied conventional brackets. Conclusion: SLBs are valid alternatives for low friction during sliding mechanics. PMID:24995241
Firuzbakht MM; Hedayati Z
2011-01-01
"nBackground and Aims: The aim of this study was to evaluate the effect of application of two types of primers over bracket bases on the shear bond strength (SBS) and mode of bond failure."nMaterials and Methods: In this study, 75 human premolar teeth were divided into three equal groups. In group 1 (control), after surface preparation of enamel by conventional method (acid etching+primer) brackets were bonded with Transbond XT composite. In group 2 (TX), brackets were bond...
Yu, Zhou; Jiaqiang, Lin; Weiting, Chen; Wang, Yi; Zhen, MinLing; Ni, Zhenyu
2014-01-01
Objectives The aim of this study was to assess the long-term stability of treatment with self-ligating brackets compared with conventional brackets. Materials and methods The long-term follow-up retrospective study sample consisted of two groups of patients: group SL (including passive and interactive self ligating braces) comprised 30 subjects treated with self-ligating brackets at a mean pretreatment (T0) age of 13.56 years, with a mean follow up period for 7.24 years; group CL comprised 30...
Plaque Index in Multi-Bracket Fixed Appliances
To compare the plaque index in patients receiving multi-bracket fixed orthodontic treatment for various factors like age, gender, socio-economic status, brushing practices, meal habits, types of brackets, types of ligations, use of mouthwash and duration of treatment. Study Design: Cross-sectional analytical study. Place and Duration of Study: Orthodontics Clinic, The Aga Khan University Hospital, from September to November 2011. Methodology: Socio-demographic and clinical modalities were defined and recorded for 131 patients having multi-bracket fixed appliances. The plaque index of subjects were recorded according to the Silness and Loe plaque index method. Independent sample t-test was used to see difference in plaque index in factors having two variables. One way ANOVA and Post-Hoc Tukey tests were used to see difference in plaque index in factors having three variables. Kappa statistics was used to assess inter examiner reliability. P-value 0.05 was taken to be significant. Results: The sample comprised of 37% males (n = 48) and 63% females (n = 83). The plaque index had statistically significant association with practice of brushing i.e., timing of brushing (p=0.001), method of brushing (p=0.08), type of ligatures (p=0.05) and frequency of visits (p=0.01). Conclusion: The plaque accumulation is significantly decreased in subjects who brush the teeth twice or more than twice a day and those who brush their teeth after breakfast. The use of interdental brush and stainless steel ligatures had significantly low plaque. Subjects presenting with more frequent appointments of short-period had significantly less plaque. (author)
Maslov indices, Poisson brackets, and singular differential forms
Esterlis, Ilya; Hedeman, Austin; Littlejohn, Robert G
2014-01-01
Maslov indices are integers that appear in semiclassical wave functions and quantization conditions. They are often notoriously difficult to compute. We present methods of computing the Maslov index that rely only on typically elementary Poisson brackets and simple linear algebra. We also present a singular differential form, whose integral along a curve gives the Maslov index of that curve. The form is closed but not exact, and transforms by an exact differential under canonical transformations. We illustrate the method with the $6j$-symbol, which is important in angular momentum theory and in quantum gravity.
Maslov indices, Poisson brackets, and singular differential forms
Esterlis, I.; Haggard, H. M.; Hedeman, A.; Littlejohn, R. G.
2014-06-01
Maslov indices are integers that appear in semiclassical wave functions and quantization conditions. They are often notoriously difficult to compute. We present methods of computing the Maslov index that rely only on typically elementary Poisson brackets and simple linear algebra. We also present a singular differential form, whose integral along a curve gives the Maslov index of that curve. The form is closed but not exact, and transforms by an exact differential under canonical transformations. We illustrate the method with the 6j-symbol, which is important in angular-momentum theory and in quantum gravity.
On the free Lie algebra with multiple brackets
D'León, Rafael S. González
2014-01-01
It is a classical result that the multilinear component of the free Lie algebra is isomorphic (as a representation of the symmetric group) to the top (co)homology of the proper part of the poset of partitions $\\Pi_n$ tensored with the sign representation. We generalize this result in order to study the multilinear component of the free Lie algebra with multiple compatible Lie brackets. We introduce a new poset of weighted partitions $\\Pi_n^k$ that allows us to generalize the result. The new p...
Arash, Valiollah; Anoush, Keivan; Rabiee, Sayed Mahmood; Rahmatei, Manuchehr; Tavanafar, Saeid
2015-01-01
Aims of the present study was to measure frictional resistance between silver coated brackets and different types of arch wires, and shear bond strength of these brackets to the tooth. In an experimental clinical research 28 orthodontic brackets (standard, 22 slots) were coated with silver ions using electroplate method. Six brackets (coated: 3, uncoated: 3) were evaluated with Scanning Electron Microscopy and Atomic Force Microscopy. The amount of friction in 15 coated brackets was measured with three different kinds of arch wires (0.019 × 0.025-in stainless steel [SS], 0.018-in stainless steel [SS], 0.018-in Nickel-Titanium [Ni-Ti]) and compared with 15 uncoated steel brackets. In addition, shear bond strength values were compared between 10 brackets with silver coating and 10 regular brackets. Universal testing machine was used to measure shear bond strength and the amount of friction between the wires and brackets. SPSS 18 was used for data analysis with t-test. SEM and AFM results showed deposition of a uniform layer of silver, measuring 8-10 μm in thickness on bracket surfaces. Silver coating led to higher frictional forces in all the three types of arch wires, which was statistically significant in 0.019 × 0.025-in SS and 0.018-in Ni-Ti, but it did not change the shear bond strength significantly. Silver coating with electroplating method did not affect the bond strength of the bracket to enamel; in addition, it was not an effective method for decreasing friction in sliding mechanics. PMID:25997114
Budd, Steven; Daskalogiannakis, John; Tompson, Bryan D
2008-12-01
The objective of this investigation was to assess and compare the in vitro tribological behaviour of four commercially available self-ligating bracket systems. The frictional characteristics of the Damon3, Speed, In-Ovation R, and Time2 bracket systems were studied using a jig that mimics the three-dimensional movements that occur during sliding mechanics. Each bracket system was tested on the following stainless steel archwires: 0.016 x 0.022, 0.019 x 0.025, 0.020 round, and 0.021 x 0.021 inch Speed D-wire. An Instron testing machine with a 50 N load cell was used to measure the frictional resistance for each bracket/tooth assembly. The crosshead speed was set at a constant rate of 1 mm/minute, and each typodont tooth was moved along a fixed wire segment for a distance of 8 mm. Descriptive statistical analysis for each bracket/archwire combination with regard to frictional resistance was performed with a two-way, balanced analysis of variance for bracket type and wire size. The Damon3 bracket consistently demonstrated the lowest frictional resistance to sliding, while the Speed bracket produced significantly (P brackets tested for any given archwire. The self-ligation design (passive versus active) appears to be the primary variable responsible for the frictional resistance generated by self-ligating brackets during translation. Passively ligated brackets produce less frictional resistance; however, this decreased friction may result in decreased control compared with actively ligated systems. PMID:18974067
Electrical servo actuator bracket. [fuel control valves on jet engines
Sawyer, R. V. (Inventor)
1981-01-01
An electrical servo actuator is mounted on a support arm which is allowed to pivot on a bolt through a fixed mounting bracket. The actuator is pivotally connected to the end of the support arm by a bolt which has an extension allowed to pass through a slot in the fixed mounting bracket. An actuator rod extends from the servo actuator to a crank arm which turns a control shaft. A short linear thrust of the rod pivots the crank arm through about 90 for full-on control with the rod contracted into the servo actuator, and full-off control when the rod is extended from the actuator. A spring moves the servo actuator and actuator rod toward the control crank arm once the actuator rod is fully extended in the full-off position. This assures the turning of the control shaft to a full-off position. A stop bolt and slot are provided to limit pivot motion. Once fully extended, the spring pivots the motion.
Nuclear techniques to identify allergenic metals in orthodontic brackets
The present study determines the elementary alloy composition of ten commercial brands of brackets, especially related to Ni, Cr, and Co metals, confirmed allergenic elements. The nuclear techniques applied in the analyses were X-ray fluorescence (XRF) - Centre National de la Recherche Scientifique, France (National Center of Scientific Research), and X-ray energy spectrometry (XRES), and Instrumental Neutron Activation Analysis (INAA) - CDTN/CNEN, Brazil. The XRES and XRF techniques identified Cr in the 10 samples analyzed and Ni in eight samples. The INAA technique identified the presence of Cr (14% to 19%) and Co (42% to 2400 ppm) in all samples. The semi-quantitative analysis performed by XRF also identified Co in two samples. The techniques were effective in the identification of metals in orthodontic brackets. The elements identified in this study can be considered one of the main reason for the allergic processes among the patients studied. This finding suggests that the patients should be tested for allergy and allergenic sensibility to metals prior to the prescription of orthodontic device. (author)
Kloukos, D.; Taoufik, E.; Eliades, T.; Katsaros, C.; Eliades, G.
2013-01-01
OBJECTIVES: The aim of the study was to evaluate the biological effects of water eluents from polycarbonate based esthetic orthodontic brackets. METHODS: The composite polycarbonate brackets tested were Silkon Plus (SL, fiber-glass-reinforced), Elan ME (EL, ceramic particle-reinforced) and Elegance
The concepts of internal transformation brackets of 4-body systems and quasi-Eular angle have been introduced in this paper. With their aid, the calculation of the 4-body hyperspherical transformation brackets can be greatly simplified by using those of the subsystems as building blocks
On the Hamilton dynamical systems with the even and odd Poisson brackets
Using the example of the supersymmetric Witten mechanics it is proved that the Hamiltonian systems with equal number of Grassmann even and Grassmann odd canonical variables are inherently characterized by the odd Poisson bracket in addition to the even one. The duality between even and odd integrals of motion under the change of the Poisson brackets parity is established for such systems
Friction Forces during Sliding of Various Brackets for Malaligned Teeth: An In Vitro Study
Vito Crincoli
2013-01-01
Full Text Available Aims. To measure the friction force generated during sliding mechanics with conventional, self-ligating (Damon 3 mx, Smart Clip, and Time 3 and low-friction (Synergy brackets using different archwire diameters and ligating systems in the presence of apical and buccal malalignments of the canine. Methods. An experimental setup reproducing the right buccal segment of the maxillary arch was designed to measure the friction force generated at the bracket/wire and wire/ligature interfaces of different brackets. A complete factorial plan was drawn up and a three-way analysis of variance (ANOVA was carried out to investigate whether the following factors affect the values of friction force: (i degree of malalignment, (ii diameter of the orthodontic wire, and (iii bracket/ligature combination. Tukey post hoc test was also conducted to evaluate any statistically significant differences between the bracket/ligature combinations analyzed. Results. ANOVA showed that all the above factors affect the friction force values. The friction force released during sliding mechanics with conventional brackets is about 5-6times higher than that released with the other investigated brackets. A quasilinear increase of the frictional forces was observed for increasing amounts of apical and buccal malalignments. Conclusion. The Synergy bracket with silicone ligature placed around the inner tie-wings appears to yield the best performance.
Shear bond strength of precoated orthodontic brackets: an in vivo study
Ali H Hassan
2010-06-01
Full Text Available Ali H HassanDepartment of Preventive Dental Sciences, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi ArabiaObjective: To evaluate the shear bond strength of precoated orthodontic brackets bonded with self-etching primer relative to that of noncoated conventionally-bonded brackets at two different time intervals.Methods: Twenty-one subjects were selected for randomized split-mouth bonding of two types of brackets to the maxillary arch. Half of the teeth had precoated brackets bonded using selfetching adhesive, and the other half had regular brackets bonded using Transbond XT adhesive. Nitinol wires were tied to the upper arch and were left until the time of debonding. The patients were randomly divided into two groups: one debonded after one hour and the other debonded two weeks after the initial wire placement. The shear bond strength was directly recorded from the patients’ mouths using an in vivo debonding device.Results: There were no significant differences in shear bond strength between the precoated and conventional groups or within each group at different time intervals. There were significant differences between anterior and posterior teeth in both the precoated and conventional groups. Conclusion: Pre-coated brackets bonded with self-etching adhesive have the same bonding strength as the conventionally bonded brackets.Keywords: shear bond, bonding, orthodontics, precoated, brackets, self-etching adhesive
Magnetic resonance imaging artifacts caused by brackets of various materials - An in vivo study
Deepti Razdan
2012-01-01
Patients who might require repeated MRI scans, can be treated orthodontically with ceramic/composite/anterior ceramic and posterior stainless steel brackets. When the region of interest is above the orbit or beyond the posterior wall of the pharynx, no demonstrable artifacts were recorded with various types of brackets included in the present study.
The tensile bond strength of new and rebonded stainless steel orthodontic brackets.
Regan, D; LeMasney, B; van Noort, R
1993-04-01
The study investigated the effect on the tensile/peel bond strength of the variables associated with the bracket base, the enamel surface, and the type of adhesive when both new and used brackets were rebonded to a previously bonded enamel surface. The tensile/peel bond strength was firstly evaluated for three different types of stainless steel orthodontic bracket/base combinations. The cast integral base gave a significantly lower bond strength than the foil-mesh and photo-etched bases. Following debonding, a group of new brackets were bonded to the teeth using a chemically-activated or a light-cured adhesive. The old adhesive had been removed from the enamel by either a hand scaler or a tungsten-carbide bur. The rebonded new brackets demonstrated a small, but statistically significant fall in bond strength. No differences were found between the enamel preparations or the adhesives. A further group of previously debonded brackets were rebonded to the same teeth. The bracket bases were prepared by either smoothing with a green stone or heating in a bunsen flame followed by sandblasting and electropolishing. Highly significant falls in bond strength were obtained with all the bases. No significant differences were found between the two methods of bracket preparation. PMID:8500538
21 CFR 872.3750 - Bracket adhesive resin and tooth conditioner.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Bracket adhesive resin and tooth conditioner. 872... and tooth conditioner. (a) Identification. A bracket adhesive resin and tooth conditioner is a device composed of an adhesive compound, such as polymethylmethacrylate, intended to cement an orthodontic...
2008-01-01
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.
Folco, Alejandra A; Benítez-Rogé, Sandra C; Iglesias, Marina; Calabrese, Diana; Pelizardi, Cristina; Rosa, Alcira; Brusca, Marisa I; Hecht, Pedro; Mateu, María E
2014-01-01
Orthodontic brackets contribute to the accumulation of bacterial plaque on tooth surfaces because they hinder oral hygiene. In contrast to conventional brackets, self-ligating brackets do not require additional parts to support the arches, thus improving dental hygiene. The aim of this study was to compare the gingival response in orthodontic patients wearing self-ligating or conventional brackets. A sample of 22 patients aged 16 to 30 years was divided into two groups: Group A, treated with selfligating brackets (Damon system) and Group B, treated with conventional brackets (Roth technique). The following were assessed during the treatment: Plaque Index (PI), Gingival Index (GI) and Probing Depth (PD), and sub-gingival samples were taken from teeth 14/24 for microbiological observation. No statistically significant difference was found between Groups A and B; p>0.05 (sign-ranked) or between PI, GI and PD at the different times (Friedman's Analysis of Variance), even though the indices were found to increase at 14 days, particularly for self-ligating brackets. The quantity and quality of microorganisms present were compatible with health on days 0, 28 and 56. As from day 14 there is a predominance of microbiota compatible with gingivitis in both groups. In the samples studied, orthodontic treatment increases bacterial plaque and inflammatory gingival response, but gingival-periodontal health can be maintained with adequate basic therapy. Self-ligating and conventional brackets produced similar gingival response. PMID:25560690
Berger, Sandrine Bittencourt; Guiraldo, Ricardo Danil; Lopes, Murilo Baena; Oltramari-Navarro, Paula Vanessa; Fernandes, Thais Maria; Schwertner, Renata de Castro Alves; Ursi, Wagner José Silva
2016-01-01
The application of bleaching agents before placement of resin-bonded fixed appliances significantly, but temporarily, reduces bond strength to tooth structure. Antioxidants have been studied as a means to remove residual oxygen that compromises bonding to bleached enamel. This in vitro study evaluated whether green tea (GT) could restore the shear bond strength between bonded orthodontic brackets and bleached enamel. Six experimental groups were compared: group 1, no bleaching plus bracket bonding (positive control); group 2, bleaching with 35% hydrogen peroxide (HP) plus bracket bonding (negative control); group 3, 35% HP plus 10% sodium ascorbate (SA) plus bracket bonding; group 4, 35% HP plus 10% GT plus bracket bonding; group 5, no bleaching plus 10% SA plus bracket bonding; group 6, no bleaching plus 10% GT plus bracket bonding. Results suggested that GT, like SA, may be beneficial for bracket bonding immediately after bleaching. PMID:27148662
Nd:YAG Laser-aided ceramic brackets debonding: Effects on shear bond strength and enamel surface
In order to evaluate the efficiency of Nd:YAG laser-aided ceramic brackets debonding technique, both ceramic brackets and metallic brackets were bonded with orthodontic adhesive to 30 freshly extracted premolars. The specimens were divided into three groups, 10 in each, according to the brackets employed and the debonding techniques used: (1) metallic brackets with shear debonding force, (2) ceramic brackets with shear debonding force, and (3) ceramic brackets with Nd:YAG laser irradiation. The result showed that laser irradiation could diminish shear bond strength (SBS) significantly and produce the most desired ARI scores. Moreover, scanning electron microscopy investigation displayed that laser-aided technique induced little enamel scratch or loss. It was concluded that Nd:YAG laser could facilitate the debonding of ceramic brackets and diminish the amount of remnant adhesive without damaging enamel structure
Nd:YAG Laser-aided ceramic brackets debonding: Effects on shear bond strength and enamel surface
Han Xianglong [State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041 (China); Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Liu Xiaolin [Department of Orthodontics, Stomatology Hospital, Dalian University, Dalian 116021 (China); Bai Ding [State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041 (China); Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China)], E-mail: baiding88@hotmail.com; Meng Yao; Huang Lan [Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China)
2008-11-15
In order to evaluate the efficiency of Nd:YAG laser-aided ceramic brackets debonding technique, both ceramic brackets and metallic brackets were bonded with orthodontic adhesive to 30 freshly extracted premolars. The specimens were divided into three groups, 10 in each, according to the brackets employed and the debonding techniques used: (1) metallic brackets with shear debonding force, (2) ceramic brackets with shear debonding force, and (3) ceramic brackets with Nd:YAG laser irradiation. The result showed that laser irradiation could diminish shear bond strength (SBS) significantly and produce the most desired ARI scores. Moreover, scanning electron microscopy investigation displayed that laser-aided technique induced little enamel scratch or loss. It was concluded that Nd:YAG laser could facilitate the debonding of ceramic brackets and diminish the amount of remnant adhesive without damaging enamel structure.
Algebraic construction of a Nambu bracket for the two-dimensional vorticity equation
So far fluid mechanical Nambu brackets have mainly been given on an intuitive basis. Alternatively an algorithmic construction of such a bracket for the two-dimensional vorticity equation is presented here. Starting from the Lie-Poisson form and its algebraic properties it is shown how the Nambu representation can be explicitly constructed as the continuum limit from the structure preserving Zeitlin discretization. -- Highlights: → Generalized Hamiltonian fluid mechanics for the two-dimensional vorticity equation. → Enstrophy as Casimir of the Zeitlin (sine-bracket) truncation. → Algebraic construction of Nambu bracket by Bialynicki-Birula and Morrison method. → Infinite-mode limit yields continuum Nambu bracket. → Discussion of generalized Jacobi identity.
Sinescu, Cosmin; Negrutiu, Meda L.; Hughes, Michael; Bradu, Adrian; Todea, Carmen; Rominu, Roxana; Dodenciu, Dorin; Laissue, Philippe L.; Podoleanu, Adrian G.
2008-04-01
Despite good diagnosis and treatment planning, orthodontic treatment can fail if bonding fails. It is now common practice to address the aesthetic appearance of patients using aesthetic brackets instead of metal ones. Therefore, bonding aesthetic brackets has become an issue for orthodontists today. Orthodontic bonding is mainly achieved using composite resin but can also be performed with glass ionomer or resin cements. For improving the quality of bonding, the enamel is acid etched for 30 seconds with 38% phosphoric acid and then a bonding agent is applied. In our study we investigated and compared the quality of bonding between ceramic brackets, polymeric brackets and enamel, respectively using a new investigation method-OCT. The aim of our study was to evaluate the resin layer at the bracket base-tooth interface.
Cordasco, Giancarlo; Lo Giudice, Antonino; Militi, Angela; Nucera, Riccardo; Triolo, Giuseppe; Matarese, Giovanni
2012-01-01
Objective To investigate the resistance to sliding (RS) in self-ligating and conventional ligation bracket systems at 5 different second-order bracket angulations by using low-stiffness alignment wires in a 3-bracket experimental model and to verify the performance of the main RS components in both systems when these wires are used. Methods Interactive self-ligating brackets with closed and open slides were used for the self-ligating (SL) and conventional ligation (CL) groups, respectively; e...
Analysis of Shear Bond Strength and Morphology of Er:YAG Laser-Recycled Ceramic Orthodontic Brackets
Ruo-qiao Han; Kai Yang; Ling-fei Ji; Chen Ling
2016-01-01
Objective. The aim of this study was to compare the recycling of deboned ceramic brackets via an Er:YAG laser or via the traditional chairside processing methods of flaming and sandblasting; shear bond strength and morphological changes were evaluated in recycled brackets versus new brackets. Materials and Methods. 3M Clarity Self-Ligating Ceramic Brackets with a microcrystalline base were divided into groups subjected to flaming, sandblasting, or exposure to an Er:YAG laser. New ceramic brac...
Luiz Carlos Campos Braga; Mario Vedovello Filho; Mayury Kuramae; Heloísa Cristina Valdrighi; Sílvia Amélia Scudeler Vedovello; Américo Bortolazzo Correr
2011-01-01
OBJETIVO: o objetivo deste estudo foi verificar a fricção no braquete (Roth, Composite, 10.17.005, 3,2mm, largura 0,022" x 0,030", Torque -2° e angulação +13°, Morelli®, Brasil), utilizando fios ortodônticos retangulares de 0,019" x 0,025" de aço inoxidável (Morelli®, Brasil) e de níquel-titânio superelásticos Bioforce com IonGuard e sem IonGuard (Bioforce, GAC®, EUA). MÉTODOS: foram utilizados 24 conjuntos braquetes/segmento de fio, divididos em 3 grupos de acordo com o fio. Cada conjunto br...
Vanessa Nínia Correia Lima; Maria Elisa Rodrigues Coimbra; Carla D'Agostini Derech; Antônio Carlos de Oliveira Ruellas
2010-01-01
OBJETIVO: a finalidade deste estudo in vitro foi avaliar e comparar a resistência friccional em braquetes de aço inoxidável e de policarbonato compósito amarrados com fio metálico e elastômeros. MÉTODOS: foram utilizados quatro braquetes de aço inoxidável e quatro de policarbonato compósito (PC) para pré-molares levados à máquina universal de ensaio mecânico para a tração de um segmento de fio de aço inoxidável 0,019" x 0,025" na velocidade de 0,5mm/min, com 8mm de deslocamento total. A forma...
Physical and chemical properties of orthodontic brackets after 12 and 24 months: in situ study
MENDES, Bernardo de Azevedo Bahia; FERREIRA, Ricardo Alberto Neto; PITHON, Matheus Melo; HORTA, Martinho Campolina Rebello; OLIVEIRA, Dauro Douglas
2014-01-01
Objective The aim of this article was to assess how intraoral biodegradation influenced the surface characteristics and friction levels of metallic brackets used during 12 and 24 months of orthodontic treatment and also to compare the static friction generated in these brackets with four different methods of the ligation of orthodontic wires. Material and Methods Seventy premolar brackets as received from the manufacturer and 224 brackets that were used in previous orthodontic treatments were evaluated in this experiment. The surface morphology and the composition of the deposits found in the brackets were evaluated with rugosimetry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Friction was analyzed by applying tensile tests simulating sliding mechanics with a 0.019x0.025" steel wire. The static friction levels produced by the following ligation methods were evaluated: loosely attached steel ligature around all four bracket wings, steel ligature attached to only two wings, conventional elastomeric ligation around all 4 bracket wings, and non-conventional Slide® elastomeric ligature. Results The results demonstrated the presence of biodegradation effects such as corrosion pits, plastic deformation, cracks, and material deposits. The main chemical elements found on these deposits were Carbon and Oxygen. The maximum friction produced by each ligation method changed according to the time of intraoral use. The steel ligature loosely attached to all four bracket wings produced the lowest friction levels in the new brackets. The conventional elastic ligatures generated the highest friction levels. The metallic brackets underwent significant degradation during orthodontic treatment, showing an increase in surface roughness and the deposit of chemical elements on the surface. Conclusion The levels of static friction decreased with use. The non-conventional elastic ligatures were the best alternative to reduce friction. PMID:25025560