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Sample records for argonio utilizando-se brackets

  1. In vitro comparative study of share bond of light cured composite resins with halogen light and argon laser, using stainless steel brackets on human premolars; Estudo comparativo in vitro da capacidade adesiva da resina fotoativada pela luz halogena e por laser de argonio, utilizando-se brackets metalicos em pre-molares humanos

    Energy Technology Data Exchange (ETDEWEB)

    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

  2. Lazy & quarrelsome brackets

    NARCIS (Netherlands)

    Visser, A.

    2008-01-01

    In this paper we study two (kinds of) systems of brackets in an algebraic way. Lazy brackets have the same effect as introducing or eliminating 'a sufficient amount' of ordinary brackets at the same time. Quarrelsome brackets are brackets corresponding to different types of 'levels': think e.g. of t

  3. Breket titanium (Titanium bracket

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    Sianiwati Goenharto

    2005-09-01

    Full Text Available There has been a considerable discussion in the literature about corrosion and sensitivity to the nickel present in stainless steel brackets. Titanium has been heralded as a material totally compatible in the oral environment and superior in structural integrity compared to stainless steel. Many current applications in dentistry and medicine have made titanium an obvious choice for a possible substitute material. Titanium based brackets have shown excellent corrosion resistance and possessed good biocompatibility. Evaluation of titanium brackets for orthodontic therapy showed that titanium brackets were comparable to stainless steel brackets in passive and active configuration. Study about metallographic structure, hardness, bond strength to enamel substrate, etc. showed that titanium brackets exhibited a potential for clinical application. It was concluded that titanium brackets were suitable substitute for stainless steel brackets.

  4. Quantum and Classic Brackets

    OpenAIRE

    Kisil, Vladimir V.

    2000-01-01

    We describe an $p$-mechanical (see funct-an/9405002 and quant-ph/9610016) brackets which generate quantum (commutator) and classic (Poisson) brackets in corresponding representations of the Heisenberg group. We \\emph{do not} use any kind of semiclassic approximation or limiting procedures for $\\hbar \\to 0$. Harmonic oscillator considered within the approach. Keywords: Classic and quantum mechanics, Hamilton and Heisenberg equations, Poisson brackets, commutator, Heisenberg group.

  5. Correlates of Narrow Bracketing

    DEFF Research Database (Denmark)

    Koch, Alexander; Nafziger, Julia

    We examine whether different phenomena of narrow bracketing can be traced back to some common characteristic and whether and how different phenomena are related. We find that making dominated lottery choices or ignoring the endowment when making risky choices are related phenomena and are both as...

  6. Bracketing effects on risk tolerance

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    Ester Moher

    2010-08-01

    Full Text Available Research has shown that risk tolerance increases when multiple decisions and associated outcomes are presented together in a broader ``bracket'' rather than one at a time. The present studies disentangle the influence of problem bracketing (presenting multiple investment options together from that of outcome bracketing (presenting the aggregated outcomes of multiple decisions, factors which have been deliberately confounded in previous research. In the standard version of the bracketing task, in which participants decide how much of an initial endowment to invest into each in a series of repeated, identical gambles, we find a problem bracketing effect but not an outcome bracketing effect. However, this pattern of results does not generalize to the cases of non-identical gambles nor discrete choice, where we fail to find the standard bracketing effect.

  7. Degradação redutiva de azo-corantes utilizando-se ferro metálico Reductive degradation of azo-dyes by metallic iron

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    Cláudio Lima de Souza

    2006-03-01

    Full Text Available Corantes azo são extensivamente utilizados em processos de tingimento de fibras têxteis, sendo caracterizados por elevada resistência frente a processos aeróbios de biodegradação e, por conseqüência, persistência nos processos convencionais de tratamento de resíduos. Neste trabalho reporta-se a degradação redutiva de corantes azo, utilizando-se ferro metálico. Em condições experimentais otimizadas (pH 7 e 10 g de lã de aço comercial a completa descoloração do corante modelo (preto reativo 5 foi conseguida em um sistema contínuo, operando com tempos de retenção de 6 min. Nestas condições, o ferro solubilizado alcança concentrações compatíveis com os limites impostos pela atual legislação brasileira (12 mg L-1. Trata-se de um resultado bastante promissor, principalmente levando-se em consideração o caráter recalcitrante dos azo corantes e a simplicidade do sistema proposto.Azo dyes are extensively used in textile dying processes and are characterized by extreme resistance to biodegradation and consequently persistence during conventional wastewater treatment processes. In this work the reductive degradation of azo dyes was studied using zero-valent iron. At optimized experimental conditions (pH 7 and 10 g of commercial iron wool complete decolorization of the model dye (reactive black 5 was afforded in a continuous system operating with hydraulic retention time of 6 min. At these conditions the released total soluble iron reaches a concentration compatible with the limits imposed by the current Brazilian legislation (12 mg L-1. That is a very promising result, mainly taking into account the high recalcitrant character of azo dyes and the simplicity of the proposed system.

  8. A prevalência de cárie e determinação do crescimento ponderal e corporal utilizando-se a dieta básica regional modificada - estudo em ratos

    OpenAIRE

    Paula Alves Figueiredo Lima, Ana

    2005-01-01

    Os objetivos da presente pesquisa foram determinar a prevalência de cárie em molares e o crescimento ponderal e corporal de ratos (Rattus norvegicus albinus Wistar), utilizando-se a Dieta Básica Regional Modificada incluindo elementos nutricionais da região, acrescida ou não de flúor. Foram utilizados 60 ratos, do sexo masculino, com 23 dias de idade. Estes animais foram divididos aleatoriamente em cinco grupos, os quais receberam, durante 120 dias, os seguintes tratamentos: gr...

  9. Adhesives for orthodontic bracket bonding

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    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.

  10. Avaliação de características de carcaça de suínos utilizando-se a análise dos componentes principais Evaluation of swine carcass traits using principal components

    OpenAIRE

    Leandro Barbosa; Paulo Sávio Lopes; Adair José Regazzi; Simone Eliza Facioni Guimarães; Robledo de Almeida Torres

    2005-01-01

    Dados de 367 animais de uma população F2 de suínos foram utilizados na análise estatística, utilizando-se os componentes principais, para avaliação da possibilidade de redução da dimensionalidade do espaço multivariado em 33 características de carcaça. Dos 33 componentes principais, 17 apresentaram variância inferior a 0,7 (autovalor inferior a 0,7), que sugere 17 variáveis para descarte e correlação linear simples significativa com as demais, ou seja, foram redundantes. Com base nos resultad...

  11. Avaliação de características de carcaça de suínos utilizando-se a análise dos componentes principais

    OpenAIRE

    Barbosa, Leandro; Lopes,Paulo de Sávio; Regazzi,Adair José; Guimarães,Simone Eliza Facioni; Torres, Robledo Almeida

    2005-01-01

    Dados de 367 animais de uma população F2 de suínos foram utilizados na análise estatística, utilizando-se os componentes principais, para avaliação da possibilidade de redução da dimensionalidade do espaço multivariado em 33 características de carcaça. Dos 33 componentes principais, 17 apresentaram variância inferior a 0,7 (autovalor inferior a 0,7), que sugere 17 variáveis para descarte e correlação linear simples significativa com as demais, ou seja, foram redundantes. Com base nos resultad...

  12. Derived bracket construction up to homotopy

    CERN Document Server

    Uchino, K

    2012-01-01

    We will introduce the notion of higher derived bracket construction in the category of operads and prove that the higher derived bracket construction of Lie operad is equivalent with the cobar construction of Leibniz operad.

  13. Structural support bracket for gas flow path

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Fertigação em mudas de citros utilizando-se mangueiras e microtubos sob regime de escoamento turbulento Fertigation on citrus seedlings using hoses and microtubes under turbulent flow regime

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    Wanderley J. Souza

    2011-08-01

    Full Text Available A irrigação localizada utilizando-se microtubo como emissor operando em regime de escoamento turbulento, pode ser uma alternativa viável, tanto técnica como economicamente para a produção de mudas de citros. Objetivou-se, com este trabalho, avaliar o desempenho de um sistema de fertigação na produção de mudas de laranja em viveiro projetado pelo modelo matemático universal, utilizando-se microtubos como emissores, sob regime de escoamento turbulento e comparar o desenvolvimento das plantas fertigadas por microtubos com o sistema em que se utiliza o método tradicional com mangueiras. No dimensionamento do comprimento dos emissores considerou-se o coeficiente K de dissipação de energia localizada através de um microtubo com diâmetro interno de 0,761 mm. O sistema de fertigação apresentou bom desempenho, com valores de grau de entupimento, uniformidade de Christiansen e uniformidade de emissão iguais a 0,50; 99,95 e 98,21%, respectivamente, após 160 dias de estudo. As plantas cultivadas via fertigação com microtubos e mangueiras, não apresentaram diferenças no que se refere ao diâmetro do caule e à altura. Desta forma, o uso de microtubo sob escoamento turbulento apresentou viabilidade técnica para fertigação.The use of localized irrigation using microtube as emitter under turbulent flow regime can be a technically feasible alternative. The objective of this study was to evaluate the performance of a fertigation system in nursery of citrus plants (greenhouse projected by universal mathematical model, using the microtubes as emitters, under turbulent flow rate and to compare the development of the fertigated plants by microtubes to the system that use the traditional method with hoses. In the size of the length of the emitters was considered the K coefficient of localized energy dissipation using a microtube with internal diameter of 0,761 mm. The fertigation system presented great performance with clogging degree

  15. Aspectos ultrassonográficos associados à morbidade de formas clínicas crônicas de esquistossomose mansônica, utilizando-se protocolo proposto pela Organização Mundial da Saúde

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    Daniel Alvarenga Fernandes

    2013-02-01

    Full Text Available OBJETIVO: Avaliar aspectos ultrassonográficos associados à morbidade em pacientes com formas clínicas crônicas de esquistossomose mansônica, utilizando-se protocolo proposto pela Organização Mundial da Saúde (OMS. MATERIAIS E MÉTODOS: Foram avaliadas duas populações distintas: a área endêmica e b institucional terciária, com histopatológico confirmando fibrose. Critérios de inclusão: diagnóstico confirmado por parasitológico de fezes para Schistosoma mansoni (método Kato-Katz. Critérios de exclusão: sorologia positiva para HIV, HTLV-1, VHB ou VHC. Foi utilizado protocolo ultrassonográfico de Niamey, proposto pela OMS. RESULTADOS: Avaliando-se isoladamente as medidas dos espaços periportais, estas se mostraram sem alterações em 21% dos indivíduos com doença avançada da instituição terciária. Utilizando-se todos os parâmetros do protocolo, 100% dos indivíduos da instituição terciária, com forma grave da doença, apresentaram fibrose periportal avançada. Em pacientes hepatoesplênicos da área endêmica não se identificou fibrose à ultrassonografia. CONCLUSÃO: O protocolo ultrassonográfico proposto pela OMS detecta fibrose periportal avançada nos pacientes com forma grave da doença, com maior sensibilidade do que a medida do espaço periportal isoladamente. A complexidade de identificação das fases iniciais da fibrose periportal, em áreas endêmicas, pela ultrassonografia, pode suscitar o campo da complementação diagnóstica e a continuidade do aprimoramento dos protocolos ultrassonográficos nestas áreas.

  16. Effect of delayed polymerization time and bracket manipulation on orthodontic bracket bonding

    Science.gov (United States)

    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.

  17. A hierarchy of Poisson brackets

    CERN Document Server

    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...

  18. Delayed bracket placement in orthodontic treatment

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    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.

  19. Nambu bracket and M-theory

    CERN Document Server

    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).

  20. Shear Bond Strength of Bracket Bases to Adhesives Based on Bracket Base Design

    Science.gov (United States)

    2016-04-13

    bracket compared to the surface of the substrate. Recent research and development have resulted in the production of various bracket base designs other...designs has been offered by ODP’s state of the art Anchor-Lock TM Pad which claims to take bonding to a whole new level. With this bracket, the base ...FUTURE RESEARCH When metal bracket bases are debonded, the site of failure occurs predominately at the adhesive- base interface. This failure site

  1. Torque expression in self-ligating orthodontic brackets and conventionally ligated brackets: A systematic review

    Science.gov (United States)

    Al-Thomali, Yousef; Mohamed, Roshan-Noor; Basha, Sakeenabi

    2017-01-01

    Background To evaluate the torque expression of self ligating (SL) orthodontic brackets and conventionally ligated brackets and the torque expression in active and passive SL brackets. Material and Methods Our systematic search included MEDLINE, EMBASE, CINAHL, PsychINFO, Scopus, and key journals and review articles; the date of the last search was April 4th 2016. We graded the methodological quality of the studies by means of the Quality Assessment Tool for Quantitative Studies, developed for the Effective Public Health Practice Project (EPHPP). Results In total, 87 studies were identified for screening, and 9 studies were eligible. The quality assessment rated one of the study as being of strong quality, 7 (77.78%) of these studies as being of moderate quality. Three out of 7 studies which compared SL and conventionally ligated brackets showed, conventionally ligated brackets with highest torque expression compared to SL brackets. Badawi showed active SL brackets with highest torque expression compared to passive SL brackets. Major and Brauchli showed no significant differences in torque expression of active and passive SL brackets. Conclusions Conventionally ligated brackets presented with highest torque expression compared to SL brackets. Minor difference was recorded in a torque expression of active and passive SL brackets. Key words:Systematic review, self ligation, torque expression, conventional ligation. PMID:28149476

  2. Multiple q-Zeta Brackets

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    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.

  3. Clinical Survival of Rebonded Brackets with Different ARI Scores

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    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

  4. Frictional resistance of self-ligating versus conventional brackets in different bracket-archwire-angle combinations

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    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.

  5. Avaliação de características de carcaça de suínos utilizando-se a análise dos componentes principais Evaluation of swine carcass traits using principal components

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    Leandro Barbosa

    2005-12-01

    Full Text Available Dados de 367 animais de uma população F2 de suínos foram utilizados na análise estatística, utilizando-se os componentes principais, para avaliação da possibilidade de redução da dimensionalidade do espaço multivariado em 33 características de carcaça. Dos 33 componentes principais, 17 apresentaram variância inferior a 0,7 (autovalor inferior a 0,7, que sugere 17 variáveis para descarte e correlação linear simples significativa com as demais, ou seja, foram redundantes. Com base nos resultados, recomenda-se que as seguintes variáveis sejam mantidas em experimentos futuros: idade ao abate; peso da meia-carcaça direita; comprimento da carcaça pelo Método Brasileiro de Classificação de Carcaça; maior espessura de toucinho na região da copa, na linha dorso-lombar; profundidade de lombo; e pesos do baço, do coração, da meia-carcaça direita resfriada, do pernil, da copa, da paleta, do carré, das costelas, da papada, do filezinho e do rim.Principal component analyses were applied to carcass records of 367 animals of a F2 swine population. Starting from 33 traits, 17 showed variation lower than 0.7 (eigenvalue lower than 0.7 and significant simple linear correlations with the other traits, indicating they were redundant. These results suggest the following variables to be used in future carcass studies: slaughter age; right side carcass weight; carcass length by the Brazilian Method of Carcass Classification; higher backfat thickness at boston shoulder area and in the midline; loin depth; spleen, heart, cold right side carcass, ham, boston shoulder, picnic shoulder, loin (bone-in, spareribs, jowl, sirloin and kidney weights.

  6. Are torque values of preadjusted brackets precise?

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    Alessandra Motta Streva

    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.

  7. Are torque values of preadjusted brackets precise?

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    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.

  8. Poisson Bracket on the Space of Histories

    CERN Document Server

    Marolf, D

    1994-01-01

    We extend the Poisson bracket from a Lie bracket of phase space functions to a Lie bracket of functions on the space of canonical histories and investigate the resulting algebras. Typically, such extensions define corresponding Lie algebras on the space of Lagrangian histories via pull back to a space of partial solutions. These are the same spaces of histories studied with regard to path integration and decoherence. Such spaces of histories are familiar from path integration and some studies of decoherence. For gauge systems, we extend both the canonical and reduced Poisson brackets to the full space of histories. We then comment on the use of such algebras in time reparameterization invariant systems and systems with a Gribov ambiguity, though our main goal is to introduce concepts and techniques for use in a companion paper.

  9. Analysis of mesiodistal angulations of preadjusted brackets

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    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.

  10. Operação de Rastelli utilizando-se conduto valvulado de pericárdio bovino: experiência inicial Rastelli operation with bovine pericardium valved conduit: early experience

    Directory of Open Access Journals (Sweden)

    Carlos R Moraes

    1988-08-01

    Full Text Available O presente trabalho descreve a experiência inicial com a operação de Rastelli, utilizando-se um conduto valvulado de pericárdio bovino preservado em glutaraldeído. O enxerto consta de um conduto, que serve para reconstruir a via de saída do ventrículo direito e o tronco pulmonar, com uma válvula tricúspide suturada em seu interior sem anel de suporte, permitindo, assim, um mecanismo de fluxo unidirecional. De maio de 1986 a outubro de 1987, 5 crianças foram submetidas à operação de Rastelli empregando-se este tipo de conduto valvulado. Três eram do sexo feminino e 2, do masculino, variando a idade de 1 a 8 anos x 5. Três pacientes tinham transposição das grandes artérias, comunicação interventricular (CIV e estenose subpulmonar. Uma criança era portadora de atresia pulmonar com CIV e de um shunt prévio tipo Waterston e, finalmente, a outra tinha um tronco arterial comum tipo II. Dois doentes faleceram de causas não relacionadas ao tipo de conduto valvulado utilizado. O conduto valvulado de pericárdio bovino preservado em glutaraldeído mostrou excelente flexibilidade, facilitando o manuseio cirúrgico e permitindo perfeita adaptabilidade dentro do saco pericárdico. A ausência de anel de suporte tem a vantagem de eliminar qualquer gradiente e de abolir o turbilhonamento do sangue - causas reconhecidas de calcificação.The present report describes the initial experience with the Rastelli operation utilizing a composite graft of glutaraldehyde preserved bovine pericardium. The graft is made up of a tube which serves to reconstruct the outflow tract of the right ventricle and the pulmonary artery, and an inner tricuspid valve, without a supporting ring, which provides the tube with a one-way flow mechanism. From May, 1986 to October, 1987, five children were submitted to Rastelli operation utilizing this valved tube. Three were female and two male, ranging in age from 1 e to 8 years (mean 5 years. Three had transposition

  11. Condutividade hidráulica de um Latossolo Vermelho Amarelo, não-saturado, utilizando-se sonda de nêutrons = Unsaturated hydraulic conductivity of an Oxisol, using a neutron probe

    Directory of Open Access Journals (Sweden)

    Laércio Alves Carvalho

    2010-01-01

    Full Text Available O objetivo deste estudo foi determinar a condutividade hidráulica não-saturada, utilizando-se sonda de nêutrons, em um Latossolo Vermelho distrófico argissólico A moderado textura média. O estudo foi desenvolvido no campo experimental da Escola Superior deAgricultura ‘Luiz de Queiroz’, Universidade de São Paulo, município de Piracicaba, Estado de São Paulo, Brasil. A parcela experimental apresentava comprimento de 45 m e largura de 15 m, na qual foram instalados 40 tubos de alumínio para acesso de uma sonda de nêutrons para medida do conteúdo da água no solo nas profundidades 0,20; 0,40; 0,60; 0,80 e 1,00 m e cálculo da armazenagem no perfil 0 - 1,00 m. Os tubos foram distribuídos na forma de grade de quatro colunas por dez linhas, com cada tubo distando 5 m de seu vizinho. As funções K(θ nos 40 pontos foram determinadas a partir das análises de regressão de θ em função de lnt e hZ em função de lnt, durante o processo de redistribuição da água no solo. A sonda de nêutrons mostrou-se um equipamento eficiente na determinação do conteúdo de água no solo, no método do perfil instantâneo para determinação da função K(θ em solo homogêneo. The objective of this study was to determine the unsaturated hydraulic conductivity, using a neutron probe, of a clay sandy Oxisol. The study was carried out in the city of Piracicaba, State ofSão Paulo, Brazil (22º42’ 43.3’’ S, 47o 37’ 10.4’’ W, 546 m. The dimensions of the experimental plot were 45 m x 15 m, in which 40 aluminum tubes were installed in order to access a neutron probe to measure the soil water content at the depths of 0.2, 0.4, 0.6, 0.8 and 1.0 m and, then, calculate the soil water storage of the 0 - 1.0 m soil layer. The distribution of these tubes was made in grids of four columns by ten rows, in spacing of 5 x 5 m. The K(θ functions were determined in the 40 points from regression analyses of θ as function lnt and hz as a function of

  12. 21 CFR 872.5470 - Orthodontic plastic bracket.

    Science.gov (United States)

    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...

  13. Estudo da remoção do íon Fe (II em colunas de leito fixo, utilizando-se a Zeólita NaY - doi: 10.4025/actascitechnol.v33i3.8408

    Directory of Open Access Journals (Sweden)

    Indianara Conceição Ostroski

    2011-07-01

    Full Text Available Neste trabalho foi investigada a remoção do íon ferro em colunas de leito fixo pela zeólita NaY na temperatura de 30ºC e pH de 4,5. As curvas de ruptura experimentais foram obtidas com concentrações de alimentação de 0,2 a 2,94 meq L-1 e com vazão de 8 mL min.-1. Por meio das curvas de ruptura foi possível avaliar o comportamento da isoterma, a qual se mostrou favorável à remoção de ferro com uma quantidade máxima de retenção experimental de 2,61 meq g-1. Os dados de equilíbrio foram ajustados, utilizando-se o modelo de Langmuir e Freundlich. Também foi empregado um modelo matemático fenomenológico para representar os dados de ruptura experimental. O modelo foi obtido por meio de balanço de massa na fase fluida e no trocador. O parâmetro coeficiente de transferência de massa foi estimado, utilizando-se os dados experimentais da curva de ruptura. O modelo matemático representou apropriadamente a troca iônica dos íons ferro em coluna de leito fixo.

  14. Hydrodynamic Nambu Brackets derived by Geometric Constraints

    CERN Document Server

    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...

  15. Translucency of Dental Ceramic, Post and Bracket

    Directory of Open Access Journals (Sweden)

    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.

  16. Conceptual design for PSP mounting bracket

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. DETERMINAÇÃO DA CONDUTIVIDADE HIDRÁULICA E DA SORVIDADE DE UM SOLO NÃO-SATURADO UTILIZANDO-SE PERMEÂMETRO A DISCO DETERMINATION OF UNSATURATED HYDRAULIC CONDUCTIVITY AND SORPTIVITY OF A SOIL USING A DISK PERMEAMETER

    Directory of Open Access Journals (Sweden)

    EDVANE BORGES

    1999-11-01

    Full Text Available Dois métodos, utilizando permeâmetros a disco, foram usados para medir a sorvidade e a condutividade hidráulica em três horizontes de um solo de Santa Maria da Boa Vista, Pernambuco, utilizando-se potenciais de fornecimento de água de 0, -2,5, -5 e -10 cm de água. No primeiro método, a condutividade hidráulica foi obtida através de estimativas da sorvidade e do fluxo estacionário, utilizando-se apenas um permeâmetro. No segundo, as medidas da sorvidade e da condutividade hidráulica foram feitas utilizando-se valores dos fluxos estacionários, obtidos a partir de dois permeâmetros de diferentes raios. Esse segundo método apresentou resultados mais consistentes dos tempos -- gravitacional e geométrico --, e do raio característico de poros que o primeiro método. A sorvidade foi tão importante quanto a condutividade hidráulica para caracterizar o processo de infiltração. A redução brusca dos valores dos raios característicos de poros do horizonte A2/B, com mudanças no potencial de fornecimento de água, revelou a heterogeneidade da estrutura deste horizonte, permitindo identificar a influência dos volumes argilosos compactados sobre o processo de infiltração.Sorptivity and hydraulic conductivity were determined by two methods using disc permeameters. Infiltration experiments were carried out on three horizons of a representative soil of the semi-arid region, located in Santa Maria da Boa Vista, State of Pernambuco, Brazil. Water was supplied to this soil by disc permeameters at potentials of 0, -2.5, -5 and -10 cm of water. In the first method, hydraulic conductivity was measured using estimates of sorptivity and steady state fluxes. In the second, sorptivity and hydraulic conductivity were determined using measurements of steady state fluxes with two disc permeameters of different radius. Results of the second method, regarding characteristic times and characteristic pore radius, were more consistent than those of the

  18. Toothpaste Prevents Debonded Brackets on Erosive Enamel

    Directory of Open Access Journals (Sweden)

    Érico Luiz Damasceno Barros

    2015-01-01

    Full Text Available 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.

  19. Higher derived brackets, strong homotopy associative algebras and Loday pairs

    CERN Document Server

    Uchino, K

    2009-01-01

    We give a quick method of constructing strong homotopy associative algebras. This method is an associative version of (higher) derived bracket construction in the category of Lie/Leibniz algebras. We try to unify the two derived bracket constructions. For that aim we introduce a new type of algebra ``Loday pair", which is a noncommutative version of classical Leibniz pair. We give a coalgebra description of Loday pairs and study a derived bracket construction for Loday pairs.

  20. A comparative assessment of torque generated by lingual and conventional brackets

    NARCIS (Netherlands)

    Sifakakis, I.; Pandis, N.; Makou, M.; Eliades, T.; Katsaros, C.; Bourauel, C.

    2013-01-01

    The aim of this study was to assess the effect of bracket type on the labiopalatal moments generated by lingual and conventional brackets. Incognito lingual brackets (3M Unitek), STb lingual brackets (Light Lingual System; ORMCO), In-Ovation L lingual brackets (DENTSPLY GAC), and conventional 0.018

  1. Optimization of a procedure for rebonding dislodged orthodontic brackets.

    Science.gov (United States)

    Mui, B; Rossouw, P E; Kulkarni, G V

    1999-06-01

    The purpose of this study was to compare shear bond strength (SBS) of bonded and rebonded orthodontic brackets following a variety of commonly used conditioning treatments and using both light-cured and self-cured composite resin systems. Brackets debonded during the initial determination of SBS were rebonded after the removal of residual resin from enamel surfaces using five different treatments: (1) Remove residual resin using a tungsten carbide bur, re-etch enamel surface, then bond a new bracket; (2) Remove resin from the base mesh with micro-etching then rebond the same bracket, (3) Remove residual resin from the enamel surface using resin-removing pliers, recondition the enamel with an air-powder polisher, then bond a new bracket; (4) Remove residual resin using a rubber cup and pumice, then bond a new bracket; (5) Remove residual resin using pliers alone, then bond a new bracket. The results revealed that the light-cured system produced higher shear bond strength in the initial bond than the self-cured system (ptungsten carbide bur and acid-etching gave the highest SBS (difference 5.8 MPa; pfracture characteristics. The data suggest that the optimal procedure for rebonding dislodged orthodontic brackets is to resurface the enamel using a tungsten carbide bur, acid-etch the enamel, and use a new or re-use an old bracket after microetching.

  2. Evaluation of shear bond strength of different treatments of ceramic bracket surfaces Avaliação da resistência ao cisalhamento de diferentes tratamentos na superfície de braquetes cerâmicos

    Directory of Open Access Journals (Sweden)

    Patrícia Helou Ramos Andrade

    2012-08-01

    Full Text Available OBJECTIVE: To evaluate the bonding strength of the ceramic bracket and composite resin restoration interface, using four types of treatment on the base of the bracket. METHODOLOGY: 48 photoactivated composite resin discs were used (FiltekTM Z250 contained in specimens and divided into 4 groups of 12 specimens for each group according to the type of treatment performed on the base of the brackets. Once the brackets were bonded, the specimens were subjected to shear stress carried out in a universal testing machine (MTS: 810 Material Test System calibrated with a fixed speed of 0.5 mm / minute. The values obtained were recorded and compared by means of appropriate statistical tests - analysis of variance and then Tukey's test. RESULTS AND CONCLUSIONS: The surfaces of ceramic brackets conditioned with 10% hydrofluoric acid for 1 minute, followed by aluminum oxide blasting, 50µ, after silane application and primer application, was considered the best method to prepare surfaces of ceramic brackets prior to orthodontic esthetic bonding.OBJETIVO: avaliar a resistência à união da interface entre braquete cerâmico e restauração de resina composta, empregando quatro tipos de tratamento na base do braquete. MÉTODOS: foram utilizados 48 discos de resina fotoativada (Filtek® Z250 incluídos em corpos de prova, divididos em quatro grupos, com 12 espécimes em cada grupo, de acordo com o tipo de tratamento realizado na base do braquete. Uma vez colados os braquetes, os corpos de prova foram submetidos à tensão de cisalhamento, realizado numa máquina universal de ensaios (MTS: 810 Material Test System calibrada com velocidade fixa de 0,5mm/min. Os valores obtidos foram registrados e comparados por meio de médias, utilizando-se testes estatísticos adequados (análise de Variância e, posteriormente, teste de Tukey. RESULTADOS E CONCLUSÕES: o condicionamento das superfícies dos braquetes cerâmicos com ácido hidrofluorídrico a 10% por 1 minuto

  3. The quaternionic commutator bracket and its implications

    CERN Document Server

    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.

  4. Causal Poisson bracket via deformation quantization

    Science.gov (United States)

    Berra-Montiel, Jasel; Molgado, Alberto; Palacios-García, César D.

    2016-06-01

    Starting with the well-defined product of quantum fields at two spacetime points, we explore an associated Poisson structure for classical field theories within the deformation quantization formalism. We realize that the induced star-product is naturally related to the standard Moyal product through an appropriate causal Green’s functions connecting points in the space of classical solutions to the equations of motion. Our results resemble the Peierls-DeWitt bracket that has been analyzed in the multisymplectic context. Once our star-product is defined, we are able to apply the Wigner-Weyl map in order to introduce a generalized version of Wick’s theorem. Finally, we include some examples to explicitly test our method: the real scalar field, the bosonic string and a physically motivated nonlinear particle model. For the field theoretic models, we have encountered causal generalizations of the creation/annihilation relations, and also a causal generalization of the Virasoro algebra for the bosonic string. For the nonlinear particle case, we use the approximate solution in terms of the Green’s function, in order to construct a well-behaved causal bracket.

  5. Evaluation of failure characteristics and bond strength after ceramic and polycarbonate bracket debonding: effect of bracket base silanization.

    Science.gov (United States)

    Ozcan, M; Finnema, K; Ybema, A

    2008-04-01

    The objectives of this study were to evaluate the effect of silanization on the failure type and shear-peel bond strength (SBS) of ceramic and polycarbonate brackets, and to determine the type of failure when debonded with either a universal testing machine or orthodontic pliers. Silanized and non-silanized ceramic and polycarbonate brackets (N = 48, n = 24 per bracket type) were bonded to extracted caries-free human maxillary central incisors using an alignment apparatus under a weight of 750 g. All bonded specimens were thermocycled 1000 times (5-55 degrees C). Half of the specimens from each group were debonded with a universal testing machine (1 mm/minute) to determine the SBS and the other half by an operator using orthodontic debonding pliers. Failure types of the enamel surface and the bracket base were identified both from visual inspection and digital photographs using the adhesive remnant index (ARI) and base remnant index (BRI). As-received ceramic brackets showed significantly higher bond strength values (11.5 +/- 4.1 MPa) than polycarbonate brackets [6.3 +/- 2.7 MPa; (P = 0.0077; analysis of variance (ANOVA)]. Interaction between bracket types and silanization was not significant (P = 0.4408). Silanization did not significantly improve the mean SBS results either for the ceramic or polycarbonate brackets (12.9 +/- 3.7 and 6.3 +/- 2.7 MPa, respectively; P = 0.4044; two-way ANOVA, Tukey-Kramer adjustment). There was a significant difference between groups in ARI scores for ceramic (P = 0.0991) but not polycarbonate (P = 0.3916; Kruskall-Wallis) brackets. BRI values did not vary significantly for ceramic (P = 0.1476) or polycarbonate (P = 0.0227) brackets. Failure type was not significantly different when brackets were debonded with a universal testing machine or with orthodontic debonding pliers. No enamel damage was observed in any of the groups.

  6. Magnetic resonance imaging artifacts caused by brackets of various materials - An in vivo study

    OpenAIRE

    Deepti Razdan; Rani, M S

    2012-01-01

    Objectives: To evaluate and compare the artifacts caused by various brackets materials on Magnetic Resonance Imaging (MRI). Materials and Methods: Six cases were included - one control case, one case each with teeth bonded in the maxillary arch with composite brackets, ceramic brackets, stainless steel brackets, ceramic brackets in the maxillary anterior region and stainless steel brackets in the premolar region, and one case with teeth bonded in the maxillary and mandibular arch wit...

  7. Impact of Orthodontic Brackets on the Intraoral Scan Data Accuracy

    Directory of Open Access Journals (Sweden)

    Ji-Man Park

    2016-01-01

    Full Text Available This study aims to compare the impact of buccal and lingual brackets on the accuracy of dental arch data acquired by 4 different digital intraoral scanners. Two pairs of dental casts, one with buccal brackets and the other with lingual brackets, were used. Digital measurements of the 3D images were compared to the actual measurements of the dental models, which were considered standard values. The horizontal measurements included intercanine widths and intermolar widths. The Mann–Whitney U test was performed for comparisons. iTero® and Trios® both showed high accuracy with relatively small maximum deviation of measurements. iTero showed a significantly higher accuracy in most of the arch width measurements on the buccal bracket model than on the lingual model (P<0.05. Zfx IntraScan® and E4D Dentist® produced maximum deviations of more than 2 mm from both the buccal and the lingual bracket models. After comparing the degree of distortion of the arch on the digital scans with actual measurements of the same models, iTero and Trios proved to be excellent in terms of trueness and precision. Nevertheless, digital intraoral scanners should be used more cautiously in arches with lingual brackets than in those with buccal brackets.

  8. Color stability of ceramic brackets immersed in potentially staining solutions

    Directory of Open Access Journals (Sweden)

    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.

  9. Optimal design of an extrusion process for a hinge bracket

    Energy Technology Data Exchange (ETDEWEB)

    Na, Geum Ju; Jang, Myung Geun; Kim, Jong Bong [Seoul National University, Seoul (Korea, Republic of)

    2016-05-15

    This study considers process design in forming a hinge bracket. A thin hinge bracket is typically produced by bending a sheet panel or welding a hollow bar into a sheet panel. However, the hinge bracket made by bending or welding does not have sufficient durability in severe operating conditions because of the stress concentration in the bended region or the low corrosion resistance of the welded region. Therefore, this study uses forming to produce the hinge bracket part of a foldable container and to ensure durability in difficult operating conditions. An extrusion process for a T-shaped hinge bracket is studied using finite element analysis. Preliminary analysis shows that a very high forging load is required to form the bracket by forging. Therefore, extrusion is considered as a candidate process. Producing the part through the extrusion process enables many brackets to be made in a single extrusion and through successive cutting of the extruded part, thereby reducing the manufacturing cost. The design focuses on reducing the extrusion load and on ensuring shape accuracy. An initial billet is designed to reduce the extrusion load and to obtain a geometrically accurate part. The extruded part is bent frequently because of uneven material flow. Thus, extrusion die geometries are designed to obtain straight parts.

  10. Design manual for HANARO in-chimney bracket

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Jeong Soo; Cho, Y. G.; Whang, S. Y.; Wu, J. S.; Jun, B. J

    2000-06-01

    As a supplementary structure supporting the irradiation facilities, the in-chimney bracket holds guide tubes whose holding position in CT or IR is the middle part of the instrumented facility between the hole spider and the robot arm already provided in the reactor pool liner. Also, the bracket grips the upper part of the guide tubes when it is applied to hold the instrumented facility loaded in OR sites. The irradiation test will be successfully conducted since this bracket reduces the flow-induced vibration (FIV) and the dynamic response to seismic load. The installation position of the bracket is 60 cm below the top of the chimney, i.e., thermo siphoning hole position. To evaluate the structural integrity on the in-chimney bracket and the related reactor structures, ANSYS finite element analysis model is developed and the dynamic characteristics are analyzed. The seismic response analyses were performed for the in-chimney bracket and the related reactor structures of HANARO under the design earthquake response spectrum loads of OBE and SSE. The analysis results show that 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 much less than 1.0. Therefore any damage on structural integrity is not expected when the in-chimney bracket is installed at the upper part of the reactor chimney. This bracket had been designed and manufactured based on the dimensions of the as-built chimney. In the process of design and preliminary installation, chimney measurement tools, dummy chimney, and installation tools were developed and the installation procedure was prepared and verified through the installation rehearsal.

  11. Comparison of the frictional resistance between archwire and different bracket system: An in vitro study

    Directory of Open Access Journals (Sweden)

    Ajith R Pillai

    2014-01-01

    Full Text Available 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.

  12. Ligand "Brackets" for Ga-Ga Bond.

    Science.gov (United States)

    Fedushkin, Igor L; Skatova, Alexandra A; Dodonov, Vladimir A; Yang, Xiao-Juan; Chudakova, Valentina A; Piskunov, Alexander V; Demeshko, Serhiy; Baranov, Evgeny V

    2016-09-06

    The reactivity of digallane (dpp-Bian)Ga-Ga(dpp-Bian) (1) (dpp-Bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) toward acenaphthenequinone (AcQ), sulfur dioxide, and azobenzene was investigated. The reaction of 1 with AcQ in 1:1 molar ratio proceeds via two-electron reduction of AcQ to give (dpp-Bian)Ga(μ2-AcQ)Ga(dpp-Bian) (2), in which diolate [AcQ](2-) acts as "bracket" for the Ga-Ga bond. The interaction of 1 with AcQ in 1:2 molar ratio proceeds with an oxidation of the both dpp-Bian ligands as well as of the Ga-Ga bond to give (dpp-Bian)Ga(μ2-AcQ)2Ga(dpp-Bian) (3). At 330 K in toluene complex 2 decomposes to give compounds 3 and 1. The reaction of complex 2 with atmospheric oxygen results in oxidation of a Ga-Ga bond and affords (dpp-Bian)Ga(μ2-AcQ)(μ2-O)Ga(dpp-Bian) (4). The reaction of digallane 1 with SO2 produces, depending on the ratio (1:2 or 1:4), dithionites (dpp-Bian)Ga(μ2-O2S-SO2)Ga(dpp-Bian) (5) and (dpp-Bian)Ga(μ2-O2S-SO2)2Ga(dpp-Bian) (6). In compound 5 the Ga-Ga bond is preserved and supported by dithionite dianionic bracket. In compound 6 the gallium centers are bridged by two dithionite ligands. Both 5 and 6 consist of dpp-Bian radical anionic ligands. Four-electron reduction of azobenzene with 1 mol equiv of digallane 1 leads to complex (dpp-Bian)Ga(μ2-NPh)2Ga(dpp-Bian) (7). Paramagnetic compounds 2-7 were characterized by electron spin resonance spectroscopy, and their molecular structures were established by single-crystal X-ray analysis. Magnetic behavior of compounds 2, 5, and 6 was investigated by superconducting quantum interference device technique in the range of 2-295 K.

  13. Time-dependent constrained Hamiltonian systems and Dirac brackets

    Energy Technology Data Exchange (ETDEWEB)

    Leon, Manuel de [Instituto de Matematicas y Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Madrid (Spain); Marrero, Juan C. [Departamento de Matematica Fundamental, Facultad de Matematicas, Universidad de La Laguna, La Laguna, Tenerife, Canary Islands (Spain); Martin de Diego, David [Departamento de Economia Aplicada Cuantitativa, Facultad de Ciencias Economicas y Empresariales, UNED, Madrid (Spain)

    1996-11-07

    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)

  14. On the optimality of double-bracket flows

    Directory of Open Access Journals (Sweden)

    Anthony M. Bloch

    2004-01-01

    Full Text Available We analyze the optimality of the stable fixed point of the double-bracket equations. We introduce different types of optimality and prove local and global optimality results with respect to the Schatten p-norms.

  15. [Hardened anodized aluminum as a replacement material for bracket manufacture].

    Science.gov (United States)

    Fischer-Brandies, H; Bönhoff, M

    1994-12-01

    Attention has been repeatedly drawn to the problem of corrosion and the risk of allergic reaction to nickel resulting from the use of stainless steel brackets. In the search for a suitable alternative, manufacturers have turned to thin coating technology using hardened anodized aluminium. Applying resistance to corrosion and abrasion as the criteria to be met, they have selected aluminium alloy type 6082 as the material of choice. Purpose of this study is to examine the physical suitability of this material. Using the above noted alloy, 60 prototype brackets were made with a hardened anodized surface. They were then subjected to the following 3 stress tests: first an abrasion test using a tooth polishing machine, second, a deformation test using a device designed to simulate torque movement, and, third, a corrosion test. The effects on the brackets resulting from the three types of stress were evaluated by light microscopy. A quantitative analysis of the corrosion test was performed by ICP spectrometry. The control group consisted of conventional stainless steel brackets. The light microscopic analysis revealed no evidence of surface damage or signs of deformation in the prototype brackets. The steel brackets, on the other hand, showed clear signs of wear and corrosion. The quantitative analysis of the corrosion solution revealed metallic ion wear of 1.75 ng x mm-2 x h-1 for the prototypes subjected to abrasion. The steel brackets showed at a factor of around 104.6 metallic ion wear of 183 ng x mm-2 x h-1. In addition to this, no Ni ions were found in the corrosion solution of the prototype brackets.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. Corrosion behavior of self-ligating and conventional metal brackets

    Directory of Open Access Journals (Sweden)

    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.

  17. Análise das habilidades cognitivas requeridas dos candidatos ao cargo de contador na Administração Pública Federal, utilizando-se indicadores fundamentados na visão da Taxonomia de Bloom Analysis of cognitive skills required from candidate accountants in the brazilian Federal Public Administration, using indicators based on Bloom's Taxonomy

    Directory of Open Access Journals (Sweden)

    Jorge José Barros de Santana Junior

    2008-04-01

    Full Text Available O presente estudo objetiva detectar, através dos seis níveis de conhecimento da Taxonomia de Bloom, qual a tendência das habilidades cognitivas requeridas, quando da demanda por profissionais contadores pela Administração Direta e Indireta da União, utilizando-se da análise das questões de algumas recentes provas de concursos (1999 a 2006, o que evidenciará um perfil de desempenho intelectual delineado por esse setor público. A partir dessa análise, busca-se fazer uma reflexão sobre os caminhos a serem percorridos, para que o profissional contador possa atingir as demandas de desempenho intelectual exigidas pelo atual cenário de desenvolvimento tecnológico e econômico mundial. O artigo foi desenvolvido utilizando-se do método indutivo, mediante pesquisas bibliográficas e documentais, além de técnicas de investigação estatística. Aborda-se o histórico das últimas mudanças ocorridas no mercado profissional, em especial do setor público, e o entendimento dos fundamentos da Taxonomia de Bloom, apresentando como proposta alguns indicadores de aprendizagem mais voltados para uma realidade atual. O resultado da pesquisa demonstrou que não se está exigindo dos candidatos ao cargo de contador (ou com especialidade em contabilidade os mais altos indicadores de habilidades cognitivas. Verifica-se, portanto, a necessidade de mudanças efetivas nos rumos dessa profissão, para que se possa garantir o espaço almejado para todos aqueles que optaram em trabalhar e desenvolver as Ciências Contábeis.This study aims to detect, by means of the six knowledge levels in Bloom´s Taxonomy, tendencies in the cognitive abilities required when professional accountants are demanded by the Brazilian Direct and Indirect Administration, using the analysis of questions posed during some recent selection exams (1999 to 2006, to evidence the intellectual performance profile outlined by the public sector. Based on this analysis, attempts are made to

  18. Aspectos ultrassonográficos associados à morbidade de formas clínicas crônicas de esquistossomose mansônica, utilizando-se protocolo proposto pela Organização Mundial da Saúde Sonographic features associated with morbidity of chronic clinical presentations of schistosomiasis mansoni using the protocol proposed by the World Health Organization

    Directory of Open Access Journals (Sweden)

    Daniel Alvarenga Fernandes

    2013-02-01

    Full Text Available OBJETIVO: Avaliar aspectos ultrassonográficos associados à morbidade em pacientes com formas clínicas crônicas de esquistossomose mansônica, utilizando-se protocolo proposto pela Organização Mundial da Saúde (OMS. MATERIAIS E MÉTODOS: Foram avaliadas duas populações distintas: a área endêmica e b institucional terciária, com histopatológico confirmando fibrose. Critérios de inclusão: diagnóstico confirmado por parasitológico de fezes para Schistosoma mansoni (método Kato-Katz. Critérios de exclusão: sorologia positiva para HIV, HTLV-1, VHB ou VHC. Foi utilizado protocolo ultrassonográfico de Niamey, proposto pela OMS. RESULTADOS: Avaliando-se isoladamente as medidas dos espaços periportais, estas se mostraram sem alterações em 21% dos indivíduos com doença avançada da instituição terciária. Utilizando-se todos os parâmetros do protocolo, 100% dos indivíduos da instituição terciária, com forma grave da doença, apresentaram fibrose periportal avançada. Em pacientes hepatoesplênicos da área endêmica não se identificou fibrose à ultrassonografia. CONCLUSÃO: O protocolo ultrassonográfico proposto pela OMS detecta fibrose periportal avançada nos pacientes com forma grave da doença, com maior sensibilidade do que a medida do espaço periportal isoladamente. A complexidade de identificação das fases iniciais da fibrose periportal, em áreas endêmicas, pela ultrassonografia, pode suscitar o campo da complementação diagnóstica e a continuidade do aprimoramento dos protocolos ultrassonográficos nestas áreas.OBJECTIVE: To evaluate sonographic features associated with morbidity in patients with chronic clinical presentations of schistosomiasis mansoni, according to the protocol proposed by the World Health Organization (WHO. MATERIALS AND METHODS: Two distinctive populations were evaluated: a patients from an endemic area, and b patients from a tertiary institution, with histopathologically confirmed

  19. Determinação das perdas endógenas e da digestibilidade ileal da proteína e dos aminoácidos em suínos utilizando-se duas técnicas Use of different techniques to determine endogenous losses and ileal digestibility of protein and amino acids for swine

    Directory of Open Access Journals (Sweden)

    Leidimara Feregueti Costa

    2008-07-01

    Full Text Available Objetivou-se neste estudo determinar os coeficientes de digestibilidade ileal verdadeira da proteína e dos aminoácidos digestíveis de um extrato protéico de levedura utilizando-se duas técnicas - dieta isenta de proteína (DIP e dieta com caseína hidrolisada enzimaticamente (CHE - para determinação das perdas endógenas de proteína, aminoácidos e nitrogênio. Foram utilizados 12 suínos mestiços, machos castrados, com peso médio de 35 kg, submetidos previamente a cirurgia para implantação da cânula T simples. O delineamento experimental foi o inteiramente casualizado com três tratamentos (dieta com CHE; dieta isenta de proteína (DIP; e dieta com 23% do extrato protéico de levedura - ingrediente teste, quatro repetições e um animal por unidade experimental. As perdas endógenas de ácido glutâmico, ácido aspártico, lisina, arginina e serina diferiram entre as dietas; os maiores valores foram obtidos nos animais que receberam a dieta com CHE. O maior valor de perda endógena do aminoácido glicina foi determinado nos animais alimentados com a dieta DIP. Os coeficientes de digestibilidade ileal verdadeira de metionina, treonina, triptofano e serina determinados pelas perdas endógenas utilizando-se a dieta CHE foram superiores àqueles determinados utilizando a dieta DIP. As quantidades das secreções protéicas e de aminoácidos obtidas pela técnica da CHE foram maiores que as determinadas pela técnica da DIP. Os coeficientes de digestibilidade verdadeira da proteína foram menores e os dos aminoácidos, maiores, quando determinados pela técnica CHE.The objective of this study was to determine the true ileal digestibility coefficients of the protein and digestible amino acid of a yeast protein extract using two techniques - diet without protein (DIP and diet with enzime-hydrolysed casein (CHE - for the determination of protein amino acid and nitrogen losses. Twelve half-breed barrows were used, with average weight of 35

  20. Comparative analysis of slot dimension in lingual bracket systems

    Directory of Open Access Journals (Sweden)

    Dittmer Marc P

    2009-12-01

    Full Text Available Abstract Background Orthodontic treatment with fixed appliances requires - among others - the correct clinical expression of torque, which depends on the precise fitting of archwire and slot. Especially in the lingual technique torque problems become clinically more evident than in labial appliances also with respect to the vertical alignment of teeth due to different distances from the center of resistance. The purpose of the present study was to compare the preciseness of slot dimensions of different lingual bracket systems. Methods Three lingual bracket systems were included in the study (7th Generation and STb, Ormco, Glendora, CA, USA; Incognito, TOP-Service/3 M Unitek, Monrovia, CA, USA. Non destructive analysis of vertical slot dimensions was performed using precision pin gauges (Azurea, Belprahon, Switzerland that were tapered in increments of 0.002 mm (0.00008 inch. The sizes of 240 incisor and canine brackets were measured per system (total: 720. Data were compared using one-way ANOVA. A p-value Results Average slot dimensions were 0.467 mm ± 0.007 mm (0.0184 inch ± 0.0003 inch for the 7th Generation bracket system, 0.466 mm ± 0.004 mm (0.0183 inch ± 0.0001 inch for the STb bracket system and 0.459 mm ± 0.004 mm (0.0181 inch ± 0.0001 inch for the Incognito bracket system. Differences between systems were statistically significant (p Conclusions The analyzed bracket systems for lingual treatment exhibited significant differences in slot dimension that will clinically result in torque play. These aspects must be considered in lingual orthodontic treatment.

  1. Ceramic bracket debonding with Tm:fiber laser

    Science.gov (United States)

    Demirkan, İrem; Sarp, Ayşe Sena Kabaş; Gülsoy, Murat

    2016-06-01

    Lasers have the potential for reducing the required debonding force and can prevent the mechanical damage given to the enamel surface as a result of conventional debonding procedure. However, excessive thermal effects limit the use of lasers for debonding purposes. The aim of this study was to investigate the optimal parameters of 1940-nm Tm:fiber laser for debonding ceramic brackets. Pulling force and intrapulpal temperature measurements were done during laser irradiation simultaneously. A laser beam was delivered in two different modes: scanning the fiber tip on the bracket surface with a Z shape movement or direct application of the fiber tip at one point in the center of the bracket. Results showed that debonding force could be decreased significantly compared to the control samples, in which brackets were debonded by only mechanical force. Intrapulpal temperature was kept equal or under the 5.5°C threshold value of probable thermal damage to pulp. Scanning was found to have no extra contribution to the process. It was concluded that using 1940-nm Tm:fiber laser would facilitate the debonding of ceramic brackets and can be proposed as a promising debonding tool with all the advantageous aspects of fiber lasers.

  2. Bonded Bracket Assmebly for Frameless Solar Panels

    Energy Technology Data Exchange (ETDEWEB)

    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

  3. Bracketed morality revisited: how do athletes behave in two contexts?

    Science.gov (United States)

    Kavussanu, Maria; Boardley, Ian D; Sagar, Sam S; Ring, Christopher

    2013-10-01

    The concept of bracketed morality has received empirical support in several sport studies (e.g., Bredemeier & Shields, 1986a, 1986b). However, these studies have focused on moral reasoning. In this research, we examined bracketed morality with respect to moral behavior in sport and university contexts, in two studies. Male and female participants (Study 1: N = 331; Study 2: N = 372) completed questionnaires assessing prosocial and antisocial behavior toward teammates and opponents in sport and toward other students at university. Study 2 participants also completed measures of moral disengagement and goal orientation in both contexts. In most cases, behavior in sport was highly correlated with behavior at university. In addition, participants reported higher prosocial behavior toward teammates and higher antisocial behavior toward opponents in sport than toward other students at university. The effects of context on antisocial behavior were partially mediated by moral disengagement and ego orientation. Our findings extend the bracketed morality concept to prosocial and antisocial behavior.

  4. Design of an Orthodontic Torque Simulator for Measurement of Bracket Deformation

    Science.gov (United States)

    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.

  5. Kauffman brackets, character varieties, and triangulations of surfaces

    CERN Document Server

    Bonahon, Francis

    2010-01-01

    A Kauffman bracket on a surface is an invariant for framed links in the thickened surface, satisfying the Kauffman skein relation and multiplicative under superposition. This includes representations of the skein algebra of the surface. We show how an irreducible representation of the skein algebra usually specifies a point of the character variety of homomorphisms from the fundamental group of the surface to PSL_2(C), as well as certain weights associated to the punctures of the surface. Conversely, we sketch a proof of the fact that each point of the character variety, endowed with appropriate puncture weights, uniquely determines a Kauffman bracket. Details will appear elsewhere.

  6. The Kauffman bracket and the Jones polynomial in quantum gravity

    CERN Document Server

    Griego, J R

    1995-01-01

    An analysis of the action of the Hamiltonian constraint of quantum gravity on the Kauffman bracket and Jones knot polynomials is proposed. It is explicitely shown that the Kauffman bracket is a formal solution of the Hamiltonian constraint with cosmological constant (\\Lambda) to third order in \\Lambda. The calculation is performed in the extended loop representation of quantum gravity. The analysis makes use of the analytical expressions of the knot invariants in terms of the two and three point propagators of the Chern-Simons theory. Some particularities of the extended loop calculus are considered and the implications of the results to the case of the conventional loop representation are discussed.

  7. On classification of discrete, scalar-valued Poisson Brackets

    CERN Document Server

    Parodi, Emanuele

    2011-01-01

    We address the problem of classifying discrete differential-geometric Poisson brackets (dDGPBs) of any fixed order on target space of dimension 1. It is proved that these Poisson brackets (PBs) are in one-to-one correspondence with the intersection points of certain projective hypersurfaces. In addition, they can be reduced to cubic PB of standard Volterra lattice by discrete Miura-type transformations. Finally, improving a consolidation lattice procedure, we obtain new families of non-degenerate, vector-valued and first order dDGPBs, which can be considered in the framework of admissible Lie-Poisson group theory.

  8. Coprotest® quantitativo: quantificação de ovos de helmintos em amostras fecais utilizando-se sistema de diagnóstico comercial Quantitative Coprotest®: quantification of helminth eggs in fecal samples by commercial diagnostic kit

    Directory of Open Access Journals (Sweden)

    Ana Julia Urias Santos Araújo

    2003-06-01

    Full Text Available A técnica coproparasitológica de concentração em formol acetato de etila foi empregada para a quantificação de ovos de helmintos. O método quantitativo proposto foi padronizado utilizando-se o sistema comercial Coprotest® e amostras fecais contendo diferentes cargas de ovos de Ascaris lumbricoides. Para a comparação do Coprotest® quantitativo com outros métodos de quantificação de ovos, foi preparada em laboratório uma série de amostras fecais, com carga decrescente de ovos de A. lumbricoides, Trichuris trichiura e Schistosoma mansoni. Discutem-se as vantagens de se empregar um método capaz de detectar maior número de espécies de helmintos, além de protozoários, e que permita, concomitantemente, estimar a intensidade das infecções por geo-helmintos e S. mansoni nas populações. O Coprotest® quantitativo mostrou ser de aplicação viável, fornecendo resultados comparáveis a outros métodos quantitativos já descritos na literatura.The formol ethyl acetate concentration technique was applied for the quantification of helminth eggs in fecal samples. The proposed quantitative method was standardized through the use of a commercial kit, Coprotest®, and fecal samples with different counts of Ascaris lumbricoides eggs. For the comparison of the quantitative Coprotest® with other methods of egg quantification, a series of fecal samples was prepared in laboratory, with decreasing number of A. lumbricoides, Trichuris trichiura and Schistosoma mansoni eggs. It is discussed the advantages of a method that is able of detecting different helminth and also protozoa species, allowing, in concomitance, to estimate in the populations the intensity of S. mansoni and geohelminth infections. The quantitative Coprotest® showed to be feasible, providing results that were comparable to the other quantitative methods already described in the literature.

  9. Estudo da interação genótipo × ambiente sobre características de crescimento de bovinos de corte utilizando-se inferência bayesiana A study of the genotype × environment interaction for growth traits in beef cattle using Bayesian inference

    Directory of Open Access Journals (Sweden)

    Arthur dos Santos Mascioli

    2006-12-01

    Full Text Available Avaliou-se a interação genótipo × ambiente em um rebanho da raça Canchim por meio de estimativas de parâmetros genéticos dos pesos à desmama e aos 12 meses de idade, do ganho de peso diário entre essas idades e do desempenho estimado por um índice obtido de componentes principais envolvendo essas três características. O ambiente foi representado por época de nascimento (primeiro e segundo semestres e os parâmetros genéticos foram obtidos em análises bicaráter (mesma característica nas duas épocas, utilizando-se a metodologia de inferência bayesiana, por meio de amostrador de Gibbs, cujo modelo incluiu os efeitos fixos de sexo, ano e mês de nascimento do animal e idade da vaca ao parto (linear e quadrática e os efeitos aleatórios de animal e resíduo. Houve evidências de interação genótipo × época de nascimento para as características estudadas, sugerindo que as avaliações genéticas e a seleção dos animais devem ser feitas considerando-se a existência dessa interação.The objective of this study was to evaluate the genotype × environment interaction for weaning and yearling weights, daily weight gain from weaning to 12 months of age and the growth performance in Canchim (5/8 Charolais + 3/8 Zebu beef cattle estimated by a principal components analysis including those three traits. The environment was defined by season of birth (first and second semesters of the year. Genetic parameters were estimated by bayesian method with the Gibbs sampler using bivariate analyses (considering the trait in each of the two seasons as a different one and models that included the fixed effects of year and month of birth, sex and age of cow (linear and quadratic and the random effects of animal and residual. The results suggested that genetic evaluation and selection in Canchim beef cattle for the traits studied should consider the genotype and season of birth interaction.

  10. Resistência do solo à penetração, após o tráfego com dois tipos de pneus utilizando-se um equipamento para ensaio dinâmico Soil penetration resistance after the traffic with two types of tyres using the dynamic test equipment

    Directory of Open Access Journals (Sweden)

    Alberto K. Nagaoka

    2003-08-01

    Full Text Available Com este trabalho objetivou-se, principalmente, avaliar a resistência do solo à penetração, em função do tipo de pneu (diagonal e radial e da carga vertical, utilizando-se um equipamento de ensaio de pneu agrícola individual, e verificar os efeitos nas camadas do solo pela passagem do pneu. O equipamento utilizado foi projetado para ser acoplado na traseira do trator e acionado pela tomada de potência afim de realizar ensaios de pneus em condições de campo, sendo ainda, constituído, de uma caixa de transmissão mecânica de trator e instrumentos eletrônicos de medição. Este trabalho foi desenvolvido no Núcleo de Engenharia Rural da Faculdade de Ciências Agronômicas (FCA/UNESP em Botucatu. Os dados obtidos no experimento foram analisados considerando-se o delineamento experimental em blocos, no esquema de parcelas subdivididas, tendo na parcela os pneus (radial e diagonal e na subparcelas as cargas (10.000, 13.000, 16.000 e 19.000 N com cinco repetições. O pneu radial mostrou vantagem em relação ao diagonal, por apresentar menores valores de índice de cone. As cargas mais elevadas provocaram maiores valores de índice de cone e seus incrementos, nas camadas de 0 a 10 e de 10 a 20 cm.The main objective of this research was to evaluate the soil cone index results as a function of tyre type (radial and bias tyres and tyre load using a single wheel testing equipment and verifying the effect on the layers after tyre traffic. This equipment was projected for linking at the rear of a tractor and was activated by the power with the purpose of testing individual tyre under field conditions and constituted of a mechanical transmission box and electronic instruments of measurement. This study was conducted at the Agricultural Tyre Testing Center - NEMPA of Rural Engineering Department, Faculty of Agronomic Sciences, UNESP, Botucatu, SP. The data obtained were analyzed considering a random block experimental design in split plot with

  11. Otimização do uso da água no perímetro irrigado do Gorutuba, utilizando-se a técnica da programação linear Optimization of water use in the Gorutuba irrigation district, Minas Gerais (Brazil using the linear programming model

    Directory of Open Access Journals (Sweden)

    Daniel Fonseca de Carvalho

    2000-01-01

    Full Text Available Com este trabalho, objetivou-se selecionar as culturas e os meses de plantio que proporcionem a maximização da renda do agricultor e da utilização de recursos hídricos no Perímetro Irrigado do Gorutuba, utilizando-se um modelo de programação linear cuja função-objetivo visa maximizar as receitas líquidas mensais em função da área cultivada com as culturas normalmente utilizadas na região, tendo-se como restrição a área irrigável do lote e a quantidade de água disponível. A diferença observada entre as receitas líquidas obtidas na otimização, com e sem restrição de área por cultura, foi de 15,2% nos lotes empresariais e de 10,2% nos demais lotes. O sistema de distribuição de água não limita a escolha das culturas a serem implantadas no projeto Gorutuba, mas a diferença entre a ocupação das áreas irrigadas e, conseqüentemente, as receitas líquidas observadas, foram mais influenciadas pelos sistemas de irrigação utilizados que pelas variações na capacidade de retenção de água dos solos considerados.This research was developed with the objective of selecting the crops and planting dates in order to maximize the farmers income and the water resources in the Gorutuba Irrigation District. A linear programming model was used with an objective function to maximize the monthly income as a function of the cultivated area with the crops used in the region, subjected to the restrictions of the irrigated area and the availability of water. The net income differences obtained in the optimization with and without restriction in the cultivated area of yearly crops were 15.2% and 10.2%, for the large and the small farm plots, respectively. The water distribution system does not limit the crop selection in the irrigation district. The difference in the net income caused by the crops used was influenced more by the type of irrigation systems than by the soil water holding capacity.

  12. Estudo comparativo das seqüências rápidas ponderadas em T2, utilizando-se sincronização respiratória, apnéia, supressão de gordura, bobina de corpo e bobina de sinergia para a avaliação do fígado pela ressonância magnética

    OpenAIRE

    2003-01-01

    OBJETIVO: Comparar, qualitativa e quantitativamente, as imagens de ressonância magnética do fígado, ponderadas em T2, utilizando-se seqüências rápidas, diferenciadas pela técnica de controle respiratório, pela utilização de supressão de gordura e pelo tipo de bobina de radiofreqüência. MATERIAIS E MÉTODOS: Estudo prospectivo em 71 pacientes consecutivos, sendo realizadas seis seqüências para comparação: 1) supressão de gordura com sincronização respiratória e bobina de corpo; 2) supressão de ...

  13. In vitro Evaluation of Microleakage of Orthodontic Brackets Bonded Using Methacrylate and Silorane Base Composite

    Directory of Open Access Journals (Sweden)

    AR Davari

    2015-09-01

    Conclusions: The results of the current relealed that silorane-bass silorane-base composite provided low microleakage for orthodontic brackets, for this reason, it could be used it for bonding brackets.

  14. Torque expression of 0.018 and 0.022 inch conventional brackets

    NARCIS (Netherlands)

    Sifakakis, I.; Pandis, N.; Makou, M.; Eliades, T.; Katsaros, C.; Bourauel, C.

    2013-01-01

    The aim of this study was to assess the effect of the moments generated with low- and high-torque brackets. Four different bracket prescription-slot combinations of the same bracket type (Mini Diamond(R) Twin) were evaluated: high-torque 0.018 and 0.022 inch and low-torque 0.018 and 0.022 inch. Thes

  15. In vitro comparison of the retention capacity of new aesthetic brackets.

    Science.gov (United States)

    Fernandez, L; Canut, J A

    1999-02-01

    Tensile bond strength and bond failure location were evaluated in vitro for two types of aesthetic brackets (non-silanated ceramic, polycarbonate) and one stainless steel bracket, using bovine teeth as the substrate and diacrylate resin as the adhesive. The results show that metallic bracket had the highest bond strength (13.21 N) followed by the new plastic bracket (12.01 N), which does not require the use of a primer. The non-silanated ceramic bracket produced the lowest bond strength (8.88 N). Bond failures occurred mainly between bracket and cement, although a small percentage occurred between the enamel-cement interface with the metal and plastic brackets and within the cement for the plastic bracket. With the ceramic bracket all the failures occurred at the bracket-cement interface. This suggests that the problems of enamel lesions produced by this type of bracket may have been eliminated. The results also show that the enamel/adhesive bond is stronger than the adhesive/bracket bond in this in vitro study.

  16. 21 CFR 872.3750 - Bracket adhesive resin and tooth conditioner.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Bracket adhesive resin and tooth conditioner. 872... SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3750 Bracket adhesive resin and tooth conditioner. (a) Identification. A bracket adhesive resin and tooth conditioner is a...

  17. Histological evaluation after electrothermal debonding of ceramic brackets

    Directory of Open Access Journals (Sweden)

    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.

  18. Multiple Bracket Function, Stirling Number, and Lah Number Identities

    OpenAIRE

    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.

  19. Commutativity of missing label operators in terms of Berezin brackets

    Energy Technology Data Exchange (ETDEWEB)

    Boya, Luis J [Dpto. Fisica Teorica, Facultad de Ciencias, Universidad de Zaragoza, E-50009 Zaragoza (Spain); Campoamor-Stursberg, Rutwig [Dpto. GeometrIa y TopologIa, Fac. CC. Matematicas, Universidad Complutense de Madrid, Plaza de Ciencias, 3 E-28040 Madrid (Spain)], E-mail: luisjo@unizar.es, E-mail: rutwig@mat.ucm.es

    2009-06-12

    We obtain a criterion on the commutativity of polynomials in the enveloping algebra of a Lie algebra in terms of an involution condition with respect to the Berezin bracket. As an application, it is shown that the commutativity requirement of missing label operators for reduction chains in the missing label problem can be solved analytically.

  20. On covariant Poisson brackets in classical field theory

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. q-deformed Star Products and Moyal Brackets

    CERN Document Server

    Dayi, O F

    1996-01-01

    The standard and anti-standard ordered operators acting on two-dimensional q-deformed phase space are shown to satisfy algebras which can be called W_\\infty. q-star products and q-Moyal brackets corresponding to these algebras are constructed. Some applications like defining q-classical mechanics and q-path integrals are discussed.

  2. Evaluation of Perceived Acceptability, Beauty and Value of Different Orthodontic Brackets

    Directory of Open Access Journals (Sweden)

    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

  3. The Influence of No-Primer Adhesives and Anchor Pylons Bracket Bases on Shear Bond Strength of Orthodontic Brackets

    Directory of Open Access Journals (Sweden)

    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.

  4. Evaluation of failure characteristics and bond strength after ceramic and polycarbonate bracket debonding : effect of bracket base silanization

    NARCIS (Netherlands)

    Ozcan, M.; Finnema, K.; Ybema, A.

    2008-01-01

    The objectives of this study were to evaluate the effect of silanization on the failure type and shear-peel bond strength (SBS) of ceramic and polycarbonate brackets, and to determine the type of failure when debonded with either a universal testing machine or orthodontic pliers. Silanized and non-s

  5. Biomassa, atividade microbiana e FMA em rotação cultural milho/feijão-de-corda utilizando-se águas salinas Biomass, microbial activity and AMF in crop rotation system of maize/cowpea using saline water

    Directory of Open Access Journals (Sweden)

    Maria Eloneide de Jesus Bezerra

    2010-12-01

    Full Text Available O objetivo deste trabalho foi avaliar a influência da irrigação com água de alta e baixa salinidade sobre variáveis microbiológicas do solo em área submetida à rotação de cultura entre milho (Zea Mays L. e feijão-de-corda (Vigna unguiculata L.. A área destinada ao experimento foi dividida em duas subáreas, sendo realizados quatro cultivos: dois cultivos irrigados na estação seca e dois de sequeiro na estação chuvosa. O estudo foi conduzido em campo, utilizando-se o delineamento em blocos ao acaso, com cinco repetições. Nos cultivos irrigados foram usadas água com as seguintes condutividades elétricas (CEa: 0,8; 2,2; 3,6 e 5,0 dS m-1. Os cultivos de sequeiro foram realizados nas mesmas parcelas que foram cultivadas na estação seca, as quais permaneceram demarcadas e identificadas. No início e ao final de cada cultivo, foram coletadas amostras em duas subáreas na região radicular das plantas, no terço médio da fileira central de cada parcela. O aumento da salinidade da água de irrigação promoveu aumento do número total de esporos de fungos micorrízicos arbusculares FMA e reduziu a respiração basal do solo, o carbono da biomassa e o coeficiente metabólico microbiano (qCO2, principalmente na área cultivada com feijão-de-corda. O gênero Glomus respondeu por mais de 70% dos esporos totais encontrados, sendo que essa percentagem aumentou nos tratamentos com maior salinidade nos cultivos da estação seca. Os dados não evidenciaram qualquer efeito negativo da salinidade residual sobre as variáveis microbiológicas avaliadas, em função da irrigação com água salina durante os cultivos da estação seca.This work carred out the influence of irrigation with water of high and low salinity on soil microbial variables in area under the crop rotation between maize (Zea Mays L. and cowpea (Vigna unguiculata L.. The area for the experiment was divided into two sub areas being made four crops, two crops irrigated in

  6. In -Vitro: Evaluation of Corrosion Behavior of Orthodontic Stainless Steel Brackets to Salad Dressing

    Directory of Open Access Journals (Sweden)

    S.F.Hussain

    2016-11-01

    Full Text Available The objectives of this study were to investigate the corrosion behavior of conventional and self-ligating stainless steel brackets and the surface structural changes in response to salad dressing. Damon, In-Ovation,Smart clip, Discovery, OMNI and Masel brackets were all included in the study. For the control group, the brackets were placed in Petri dishes with Potassium Ferrocyanide (Fe [CN]6K4 and distilled water. Whereasas for the experimental group, the brackets were incorporated into the same reagent mixed with Oil-based - Kraft Classic French Oil and Water-based-Salad Magic, Herb and Garlic Dressing. The released ferrous ion concentrations were measured by spectrophotometer after 24 and 48 hours. Scanning electron microscope was used to analyze surface changes of the brackets. All types of brackets demonstrated signs of corrosion. Generally, self-ligating brackets were more susceptible to corrosion than the conventional ones the most extensive corrosion was seen in In-Ovation R™. Meanwhile, Masel was the most corroded brackets for conventional brackets.The oil-based salad dressing illustrated the most extensive corrosion in all brackets. Self-ligating brackets, Inovation R™ showed pitting corrosion on the wings. Smart clip showed surfaces corrosion only. The commonly ingested fluids aggravate the corrosive process, and this is related to sodium chloride content.

  7. Friction between different wire bracket combinations in artificial saliva: an in vitro evaluation

    Directory of Open Access Journals (Sweden)

    Tatiana Kelly da Silva Fidalgo

    2011-02-01

    Full Text Available OBJECTIVE: The objective this work was to assess the friction coefficient between brackets and wires of different materials under conditions simulating the oral environment. MATERIAL AND METHODS: Stainless steel (SS and titanium-molybdenum alloy (TMA wires of 0.019x0.025-in diameter (American Orthodontics and polycarbonate bracket (American Orthodontics, ceramic bracket (American Orthodontics, and metal bracket (3M Unitek with slots of 0.022x0.030-in were used. The friction coefficient was assessed by means of mechanical traction with the system immersed in artificial saliva. The mean roughness of both wire surface and bracket slots was evaluated by using a surface profilometer. RESULTS: The system using TMA wire and polycarbonate bracket had the highest roughness (p<0.05. SS wire with ceramic bracket had the highest friction coefficient, whereas the use of metallic bracket yielded the lowest (p<0.05. However, it was observed a statistically significant difference in the system using TMA wire and ceramic bracket compared to that using TMA wire and polycarbonate bracket (p=0.038. CONCLUSIONS: Ceramic brackets in association with SS wire should be judiciously used, since this system showed a high friction coefficient.

  8. Adherence of Streptococcus mutans and Candida albicans to different bracket materials

    Directory of Open Access Journals (Sweden)

    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.

  9. Uniform Approximation and Bracketing Properties of VC classes

    CERN Document Server

    Adams, Terrence M

    2010-01-01

    We show that the sets in a family with finite VC dimension can be uniformly approximated within a given error by a finite partition. Immediate corollaries include the fact that VC classes have finite bracketing numbers, satisfy uniform laws of averages under strong dependence, and exhibit uniform mixing. Our results are based on recent work concerning uniform laws of averages for VC classes under ergodic sampling.

  10. EFFECTS OF POTASSIUM NITRATE ON SHEAR BOND STRENGTH OF BRACKETS

    OpenAIRE

    Carrillo Barreto, Diana; Duarte Gómez, Diana; González Acuña, María E.; Madero Gómez, Sandra M.; Morales García, Harold; Delgado, Linda P.; Ordóñez Monak, Ivonne

    2014-01-01

    Introduction: During 2010 the degree research “Effects of potassium nitrate on shear bond strength of brackets” was carried out at Universidad Cooperativa de Colombia in Bogota. Objective: To determine whether the use of desensitizing with potassium nitrate affects the bond bracket strength to enamel. Materials and Methods: Forty-five human premolar teeth were randomly allocated in three groups (n = 15 each). Group 1: control (not treated), Group 2: desensitizer treated and after 24-hour brac...

  11. Orthodontic bracket bonding to glazed full-contour zirconia

    OpenAIRE

    Kwak, Ji-Young; Jung, Hyo-Kyung; Choi, Il-Kyung; Kwon, Tae-Yub

    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 profilometr...

  12. A comparative assessment of torque generated by lingual and conventional brackets.

    Science.gov (United States)

    Sifakakis, Iosif; Pandis, Nikolaos; Makou, Margarita; Eliades, Theodore; Katsaros, Christos; Bourauel, Christoph

    2013-06-01

    The aim of this study was to assess the effect of bracket type on the labiopalatal moments generated by lingual and conventional brackets. Incognito™ lingual brackets (3M Unitek), STb™ lingual brackets (Light Lingual System; ORMCO), In-Ovation L lingual brackets (DENTSPLY GAC), and conventional 0.018 inch slot brackets (Gemini; 3M Unitek) were bonded on identical maxillary acrylic resin models with levelled and aligned teeth. Each model was mounted on the orthodontic measurement and simulation system and 10 0.0175 × 0.0175 TMA wires were used for each bracket type. The wire was ligated with elastomerics into the Incognito, STb, and conventional brackets and each measurement was repeated once after religation. A 15 degrees buccal root torque (+15 degrees) and then a 15 degrees palatal root torque (-15 degrees) were gradually applied to the right central incisor bracket. After each activation, the bracket returned to its initial position and the moments in the sagittal plane were recorded during these rotations of the bracket. One-way analysis of variance with post hoc multiple comparisons (Tukey test at 0.05 error rate) was conducted to assess the effect on bracket type on the generated moments. The magnitude of maximum moment at +15 degrees ranged 8.8, 8.2, 7.1, and 5.8 Nmm for the Incognito, STb, conventional Gemini, and the In-Ovation L brackets, respectively; similar values were recorded at -15 degrees: 8.6, 8.1, 7.0, and 5.7 Nmm, respectively. The recorded differences of maximum moments were statistically significant, except between the Incognito and STb brackets. Additionally, the torque angles were evaluated at which the crown torque fell well below the minimum levels of 5.0 Nmm, as well as the moment/torque ratio at the last part of the activation/deactivation curve, between 10 and 15 degrees. The lowest torque expression was observed at the self-ligating lingual brackets, followed by the conventional brackets. The Incognito and STb lingual brackets

  13. Produção de isomaltulose a partir da transformação enzimática da sacarose, utilizando-se Erwinia sp D12 imobilizada com alginato de cálcio Production of isomaltulose from enzymatic transformation of sucrose, using Erwinia sp D12 immobilized with calcium alginate

    Directory of Open Access Journals (Sweden)

    Ana Lúcia Leite Moraes

    2005-03-01

    Full Text Available A glicosiltransferase de Erwinia sp D12 é capaz de converter a sacarose em isomaltulose (6-o-alfa-glicopiranosil D-frutofuranose, um açúcar alternativo que apresenta baixo potencial cariogênico, e que pode ser utilizado em chocolates, gomas de mascar e balas. A isomaltulose é também utilizada na produção de isomalte, uma mistura de açúcar álcool, de baixo valor calórico e baixo potencial cariogênico. No estudo da influência dos componentes do meio de cultivo, na produção de glicosiltransferase, em frascos agitados, foi obtido maior atividade da enzima (12,8 unidades de atividade/mL do meio de cultura em meio de cultura A constituído de melaço 12% (p/v de sólidos solúveis totais, peptona 4% (p/v e extrato de carne 0,4% (p/v. No estudo do efeito do tempo e da temperatura na fermentação da linhagem de Erwinia sp D12, em fermentador New Brunswick de 3L, contendo meio de cultura A, foi obtida maior atividade de glicosiltransferase (15,6 unidades de atividade/ mL de meio de cultura na fase exponencial de crescimento após 8 horas de fermentação a 30ºC. Na produção de isomaltulose a partir da sacarose utilizando-se células de Erwinia sp D12 imobilizadas em alginato de cálcio, estudou-se o efeito da temperatura (25 - 35ºC e da concentração de substrato (12,5 - 60% p/v. Foi obtido um rendimento em torno de 50% de isomaltulose, com soluções de sacarose entre 20-30% (p/v a 35ºC. Concentrações em excesso de sacarose (ao redor de 40% p/v afetaram a atividade da célula imobilizada, diminuindo a conversão de sacarose em isomaltulose. O xarope de isomaltulose foi purificado através de cromatografia de troca iônica e o eluato cristalizado por abaixamento de temperatura. Os cristais apresentaram 91,39% de isomaltulose.The glucosyltransferase of Erwinia sp D12 is able to convert sucrose into isomaltulose (6-0-alpha-D-glucopyranosyl-D-fructofuranose, an alternative sugar which presents low cariogenic potential, and can be

  14. Custos e rentabilidade da produção de juvenis de tilápia-do-nilo em tanques-rede utilizando-se diferentes densidades de estocagem Costs and profitability of juvenile Nile Tilapia breeding using different stocking densities in net cages

    Directory of Open Access Journals (Sweden)

    Luiz Marques da Silva Ayroza

    2011-02-01

    Full Text Available Neste trabalho foi realizada a análise econômica da produção de juvenis de tilápia-do-nilo em tanques-rede utilizando-se diferentes densidades de estocagem. O experimento foi desenvolvido em área aquícola, em delineamento de blocos casualizados, com quatro densidades de estocagem (100, 200, 300 e 400 peixes m-3, avaliadas com seis repetições, em dois períodos de criação: de março a abril de 2005 (52 dias - peso inicial de 43,08 ± 2,98 g e peso final de 262,14 ± 47,86 g e de março a abril de 2006 (58 dias - peso inicial de 43,16 ± 5,34 g e peso final 314,24 ± 73,30 g. Foram avaliadas as seguintes variáveis econômicas: custo da ração mais custo do juvenil dividido pela biomassa, em R$ kg-1; porcentagem do custo da ração por quilo de peixe produzido sobre o preço de venda; porcentagem do custo do juvenil por quilo de peixe produzido sobre o preço de venda e; porcentagem dos custos da ração mais do juvenil por quilo de peixe produzido sobre o preço de venda. Da menor densidade de estocagem (100 para a maior (400, ocorreu diminuição no ganho de peso diário e elevação do índice de conversão alimentar aparente, mas essa redução não comprometeu a taxa de sobrevivência. Entretanto, o ganho de biomassa aumentou com o adensamento de peixes. As maiores receitas líquidas foram obtidas nas densidades de estocagem de 100 e 200 peixes m-3. Os preços não remuneraram os custos operacionais (efetivo e total em maiores densidades (300 e 400 peixes m-3. Os melhores resultados para a produção de juvenis de tilápia-do-nilo foram obtidos com densidades de até 200 peixes m-3.It was performed in this work the economic analysis of juvenile Nile Tilapia farming using different stocking densities. The experiment was carried out in an aquaculture area, using random block designs with four stocking densities (100, 200, 300 and 400 fish m-3, evaluated with six replicates, in two rearing periods: from March to April, 2005 (52 days

  15. Estimate of the optimal level of concentrates for dairy cows on tropical pastures by using the concept of marginal analysis Estimativa do nível ótimo de concentrado para vacas leiteiras em pastos tropicais utilizando-se o conceito de análise marginal

    Directory of Open Access Journals (Sweden)

    André Soares de Oliveira

    2010-09-01

    Full Text Available It was adopted in this work a methodology to estimate the optimal level of concentrate food for dairy cows on tropical pastures based on the theory of marginal analysis. An empiric model was developed and validated for application of the methodology using a database composed of 62 means of treatments from 32 studies in which milk production was evaluated regarded to the levels of concentrate feeding. Milk production (MP showed quadratic behavior in response to concentrate intake (CI: MP (kg/cow/day = 10.554 + 1.5855CI - 0.0552CI². Evaluation of the MP values observed over the predicted ones pointed the non-rejection of the null hypothesis, indicating that the model can be applied on the prediction of milk production, and consequently, on the optimal level of supplementation. However, evaluation of the partition of mean square error of prediction indicated the need for adjustments. The marginal production response (MPR presented decreasing linear effect at CI level: MPR (kg milk/kg concentrate added = 1.5855 - 0.1104CI. The intake of concentrate that maximizes profit per animal (CIoptimum is estimated by the following equation: CIoptimum (kg/cow/day, as fed basis = (1.5855 - (Px/Py/0.1104; in which Px and Py are, respectively, the prices of concentrate feeds ($/kg, as fed basis and of the milk at farmgate ($/kg. It is suggested the realization of new studies to include in the model, indicators of reproductive performance and other factors that affect the productive response to supplementation with concentrate feeds. Recommendations on levels of concentrate feeding for bovines should be based on presuppotions of marginal response theory, in order to avoid irrational use of nutrients.Adotou-se uma metodologia para estimar o nível ótimo de alimentos concentrados para vacas leiteiras em pastos tropicais com base na teoria da análise marginal. Um modelo empírico foi desenvolvido e validado para aplicação da metodologia, utilizando-se um banco

  16. Níveis de lisina digestível em rações, utilizando-se o conceito de proteína ideal, para suínos machos castrados de alto potencial genético dos 15 aos 30 kg Dietary digestible lysine levels, using the ideal protein concept, for barrows with high genetic potential from 15 to 30 kg

    Directory of Open Access Journals (Sweden)

    Márvio Lobão Teixeira de Abreu

    2006-06-01

    Full Text Available Foram utilizados 40 leitões machos castrados, de alto potencial genético para deposição de carne magra na carcaça, com pesos inicial e final de 15,76 + 0,93 e 30,23 + 1,56 kg, respectivamente, para avaliar o efeito de níveis de lisina digestível, utilizando-se o conceito de proteína ideal, sobre o desempenho e a composição da carcaça. Os tratamentos corresponderam a uma ração basal com 19,46% de PB e 3.280 kcal de EM/kg, suplementada com L-lisina HCl, resultando em rações com 0,90; 1,.00; 1,10 e 1,20% de lisina digestível. As rações foram suplementadas com níveis crescentes de aminoácidos sintéticos, resultando em rações com relações constantes entre metionina + cistina, treonina, triptofano e valina com a lisina (60, 60, 19 e 69%, respectivamente, com base na digestibilidade verdadeira. Não se observou efeito dos tratamentos sobre o consumo diário de ração, a concentração de uréia no plasma e as porcentagens de água, proteína e gordura na carcaça dos animais. Houve efeito quadrático dos níveis de lisina digestível sobre o ganho de peso diário, que aumentou até o nível estimado de 1,10% de lisina na ração, e a conversão alimentar, que melhorou até o nível estimado de 1,12%. Houve efeito dos tratamentos sobre o consumo diário de lisina, que aumentou de forma linear. As deposições de proteína e gordura na carcaça foram influenciadas de forma quadrática, aumentando até os níveis estimados de 1,12 e 1,08% de lisina digestível, respectivamente. O nível de 1,12% de lisina digestível foi o que proporcionou os melhores resultados de desempenho e de características de carcaça de suínos machos castrados de alto potencial genético na fase de 15 a 30 kg, o que correspondeu a um consumo de lisina digestível de 12,03 g/dia (3,42 g de Lis/Mcal de EM.Fourty barrows with high genetic potential for lean gain averaging initial and final body weights of 15.76 + 0.93 kg and 30.23 + 1.56 kg, respectively

  17. Concurrent engineering solution for the design of ship and offshore bracket parts and fabrication process

    Science.gov (United States)

    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.

  18. Evaluation of Friction in Orthodontics Using Various Brackets and Archwire Combinations-An in Vitro Study

    Science.gov (United States)

    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

  19. Geometry of Vlasov kinetic moments: A bosonic Fock space for the symmetric Schouten bracket

    Energy Technology Data Exchange (ETDEWEB)

    Gibbons, John [Department of Mathematics, Imperial College London, London SW7 2AZ (United Kingdom); Holm, Darryl D. [Department of Mathematics, Imperial College London, London SW7 2AZ (United Kingdom); Computer and Computational Science Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Tronci, Cesare [Department of Mathematics, Imperial College London, London SW7 2AZ (United Kingdom); TERA Foundation for Oncological Hadrontherapy, 11 V. Puccini, Novara 28100 (Italy)], E-mail: cesare.tronci@imperial.ac.uk

    2008-06-02

    The dynamics of Vlasov kinetic moments is shown to be Lie-Poisson on the dual Lie algebra of symmetric contravariant tensor fields. The corresponding Lie bracket is identified with the symmetric Schouten bracket and the moment Lie algebra is related with a bundle of bosonic Fock spaces, where creation and annihilation operators are used to construct the cold plasma closure. Kinetic moments are also shown to define a momentum map, which is infinitesimally equivariant. This momentum map is the dual of a Lie algebra homomorphism, defined through the Schouten bracket. Finally the moment Lie-Poisson bracket is extended to anisotropic interactions.

  20. Cleansing orthodontic brackets with air-powder polishing: effects on frictional force and degree of debris

    Science.gov (United States)

    Leite, Brisa dos Santos; Fagundes, Nathalia Carolina Fernandes; Aragón, Mônica Lídia Castro; Dias, Carmen Gilda Barroso Tavares; Normando, David

    2016-01-01

    ABSTRACT Introduction: Debris buildup on the bracket-wire interface can influence friction. Cleansing brackets with air-powder polishing can affect this process. Objective: The aim of this study was to evaluate the frictional force and amount of debris remaining on orthodontic brackets subjected to prophylaxis with air-powder polishing. Methods: Frictional force and debris buildup on the surface of 28 premolar brackets were evaluated after orthodontic treatment. In one hemiarch, each bracket was subjected to air-powder polishing (n = 14) for five seconds, while the contralateral hemiarch (n = 14) served as control. Mechanical friction tests were performed and images of the polished bracket surfaces and control surfaces were examined. Wilcoxon test was applied for comparative analysis between hemiarches at p < 0.05. Results: Brackets that had been cleaned with air-powder polishing showed lower friction (median = 1.27 N) when compared to the control surfaces (median = 4.52 N) (p < 0.01). Image analysis showed that the control group exhibited greater debris buildup (median = 2.0) compared with the group that received prophylaxis with air-powder polishing (median = 0.5) (p < 0.05). Conclusion: Cleansing orthodontic brackets with air-powder polishing significantly reduces debris buildup on the bracket surface while decreasing friction levels observed during sliding mechanics. PMID:27653265

  1. Elemental composition of brazing alloys in metallic orthodontic brackets.

    Science.gov (United States)

    Zinelis, Spiros; Annousaki, Olga; Eliades, Theodore; Makou, Margarita

    2004-06-01

    The aim of this study was to assess the elemental composition of the brazing alloy of representative orthodontic brackets. The brackets examined were Gemini (3M, Unitec, Monrovia, Calif), MicroLoc (GAC, Bohemia, NY), OptiMESHxrt (Ormco, Glendora, Calif), and Ultratrim (Dentarum, Ispringen, Germany). Four metallic brackets for each brand were embedded in epoxy resin and after metallographic grinding and polishing were cleaned in a water ultrasonic bath. Scanning electron microscopy and energy-dispersive x-ray microanalysis (EDS) were used to assess the quantitative composition of the brazing alloy. Four EDS spectra were collected for each brazing alloy, and the mean value and standard deviation for the concentration of each element were calculated. The elemental composition of the brazing alloys was determined as follows (percent weight): Gemini: Ni = 83.98 +/- 1.02, Si = 6.46 +/- 0.37, Fe = 5.90 +/- 0.93, Cr = 3.52 +/- 0.34; MicroLoc: Ag = 42.82 +/- 0.18, Au = 32.14 +/- 0.65, Cu = 24.53 +/- 0.26, Mg = 1.12 +/- 0.33; OptiMESHxrt: Au = 67.79 +/- 0.97, Fe = 15.69 +/- 0.29, Ni = 13.01 +/- 0.93, Cr = 4.01 +/- 0.35; Ultratrim: Ag = 87.97 +/- 0.33, Cu = 10.51 +/- 0.45, Mg = 1.29 +/- 0.63, Zn = 1.13 +/- 0.24. The findings of this study showed that different brazing materials were used for the different brands, and thus different performances are expected during intraoral exposure; potential effects on the biological properties also are discussed.

  2. Maslov indices, Poisson brackets, and singular differential forms

    Science.gov (United States)

    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.

  3. In vitro evaluation of frictional forces of two ceramic orthodontic brackets versus a stainless steel bracket in combination with two types of archwires

    Science.gov (United States)

    Arash, Valiollah; Rabiee, Mahmoud; Rakhshan, Vahid; Khorasani, Sara; Sobouti, Farhad

    2015-01-01

    Purpose: The aim of this study was to compare frictional forces between monocrystalline alumina (MA), polycrystalline alumina (PA), and stainless steel (SS) brackets with two SS wires: Rectangular and round. Materials and Methods: In this in vitro study, 60 0.022 brackets [20 PA (0° torque, Forestadent, Germany) and 20 MA (0° torque, Ormco, California, USA)] brackets plus 20 SS brackets (0° torque, Foretadent, Germany) and 60 SS archwires (30 rectangular 0.019 ×0.025 archwires and 30 round 0.018 archwires, Ortho Technology, USA) were used in subgroups of 10 from the combination of all brackets and all archwires. A universal testing machine (Instron, Model STM 250, Germany) was used to investigate the static frictional resistance. The angulation between the bracket and wire was 0°, and the wires were pulled through the slots at a crosshead speed of 10 mm/min. Two-way and one-way analyses of variance (ANOVA) and Tukey tests were used to analyze the data. Results: Mean (SD) static frictional force for each group was as follows: MA + round: 3.47 (0.38); MA + rectangular: 4.05 (0.47); PA + round: 4.14 (0.37); PA + rectangular: 4.45 (0.65); SS + round: 3.28 (0.22); and SS + rectangular: 4.22 (0.61). Significant effects of bracket types (P = 0.001) and archwire types (P = 0.000) on the friction force were detected using ANOVA. Tukey test indicated significant differences between PA brackets with both SS and MA brackets (P < 0.05), but not between SS and MA brackets. The two archwires as well had significantly different effects (Tukey P = 0.000). Conclusions: Based on the present in-vitro study, the PA brackets might create higher frictional forces compared to both SS and MA brackets. The rectangular 0.019 ×0.025 archwire might create greater forces than round 0.018 archwire. PMID:26020037

  4. Orthodontic bracket bonding to glazed full-contour zirconia

    Science.gov (United States)

    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 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

  5. Estudo comparativo das seqüências rápidas ponderadas em T2, utilizando-se sincronização respiratória, apnéia, supressão de gordura, bobina de corpo e bobina de sinergia para a avaliação do fígado pela ressonância magnética

    Directory of Open Access Journals (Sweden)

    Abbehusen Cristiane L.

    2003-01-01

    Full Text Available OBJETIVO: Comparar, qualitativa e quantitativamente, as imagens de ressonância magnética do fígado, ponderadas em T2, utilizando-se seqüências rápidas, diferenciadas pela técnica de controle respiratório, pela utilização de supressão de gordura e pelo tipo de bobina de radiofreqüência. MATERIAIS E MÉTODOS: Estudo prospectivo em 71 pacientes consecutivos, sendo realizadas seis seqüências para comparação: 1 supressão de gordura com sincronização respiratória e bobina de corpo; 2 supressão de gordura em apnéia e bobina de corpo; 3 sem supressão de gordura com sincronização respiratória e bobina de corpo; 4 sem supressão de gordura em apnéia e bobina de corpo; 5 com supressão de gordura com sincronização respiratória e bobina de sinergia; 6 com supressão de gordura em apnéia e bobina de sinergia. A avaliação qualitativa foi baseada em três critérios: detecção de determinadas estruturas anatômicas do fígado, definição dos contornos hepáticos, e presença de artefatos de respiração. A análise quantitativa foi obtida através da relação das intensidades de sinal do fígado e do ruído de fundo. RESULTADOS: O valor médio dos índices globais de qualidade de imagem para cada uma das seis seqüências supracitadas foi de 7,8, 4,6, 7,9, 5,2, 6,7 e 4,6, respectivamente. As seqüências obtidas com sincronização respiratória apresentaram melhor qualidade de imagem e relação sinal/ruído superiores às seqüências com apnéia (p 0,05. As seqüências obtidas com bobina de sinergia apresentaram qualidade de imagem semelhante (p > 0,05 e relação sinal/ruído inferior àquelas com bobina de corpo (p < 0,001. CONCLUSÃO: Associando-se as análises qualitativa e quantitativa das imagens, as melhores seqüências foram aquelas obtidas com sincronização respiratória e bobina de corpo, utilizando-se ou não supressão de gordura.

  6. Shear bond strength of precoated orthodontic brackets: an in vivo study

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    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

  7. Magnetic resonance imaging artifacts caused by brackets of various materials - An in vivo study

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    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.

  8. Friction Forces during Sliding of Various Brackets for Malaligned Teeth: An In Vitro Study

    Science.gov (United States)

    Crincoli, Vito; Di Bisceglie, Maria Beatrice; Balsamo, Antonio; Serpico, Vitaliano; Chiatante, Francesco; Pappalettere, Carmine; Boccaccio, Antonio

    2013-01-01

    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. PMID:23533364

  9. Friction Forces during Sliding of Various Brackets for Malaligned Teeth: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    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.

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

    Institute of Scientific and Technical Information of China (English)

    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.

  11. Gingival response in orthodontic patients: Comparative study between self-ligating and conventional brackets.

    Science.gov (United States)

    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.

  12. Comparison of static friction with self-ligating, modified slot design and conventional brackets

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    Raquel Morais Castro

    2013-07-01

    Full Text Available OBJECTIVE: To compare the static frictional forces generated at the bracket/wire interface of stainless steel brackets with different geometries and angulations, combined with orthodontic wires of different diameters. MATERIAL AND METHODS: The frictional forces were evaluated with three different types of metal brackets: a passive self-ligating (SmartClipTM, 3M/Unitek, Monrovia, USA, with a modified slot design (Mini Uni TwinTM, 3M/Unitek, Monrovia, USA and conventional (Kirium, Abzil, São José do Rio Preto, Brazil. The samples were mounted in a testing device with three different angulations and tested with 0.014" and 0.018" stainless steel wires (American Orthodontics, Sheboygan, USA. The static frictional force was measured using a universal testing machine (DL 500, EMIC®, São José dos Pinhais, Brazil with a crosshead speed of 1 mm/min. Statistical analysis was performed by two-way ANOVA followed by Bonferroni's post hoc test. RESULTS: There was a significant difference (p<0.05 in static friction when the three types of brackets were tested with the same wire size. The wire diameter influenced friction only when the brackets had a 10º angulation (p<0.05. The angulation influenced friction (p<0.05 when the brackets were associated with a 0.018" wire. CONCLUSION: Brackets with a modified slot design showed intermediate static frictional force values between the conventional and self-ligating brackets tested.

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

    Institute of Scientific and Technical Information of China (English)

    HUANG Lei; LI HongBo

    2008-01-01

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

  14. Loss of surface enamel after bracket debonding : An in-vivo and ex-vivo evaluation

    NARCIS (Netherlands)

    Pont, Huib Berghauser; Özcan, Mutlu; Bagis, Bora; Ren, Yijin

    2010-01-01

    INTRODUCTION: The objective of this study was to evaluate the surface enamel after bracket debonding and residual resin removal. METHODS: Thirty patients (female, 20; male, 10; mean age, 18.4 years) who completed orthodontic treatment with fixed appliances (Twin Brackets, 3M Unitek, Monrovia, Calif)

  15. Caries outcomes after orthodontic treatment with fixed appliances: do lingual brackets make a difference?

    NARCIS (Netherlands)

    van der Veen, M.H.; Attin, R.; Schwestka-Polly, R.; Wiechmann, D.

    2010-01-01

    Orthodontic treatment with fixed appliances is considered a risk factor for the development of white spot caries lesions (WSL). Traditionally, brackets are bonded to the buccal surfaces. Lingual brackets are developing rapidly and have become more readily available. Buccal surfaces are considered to

  16. Effects of green tea on the shear bond strength of orthodontic brackets after in-office vital bleaching.

    Science.gov (United States)

    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.

  17. Nd:YAG Laser-aided ceramic brackets debonding: Effects on shear bond strength and enamel surface

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. A comparative study on time efficiency management of self ligating brackets with conventional ligating brackets on orthodontic subjects in North Karnataka

    Directory of Open Access Journals (Sweden)

    Smita B. Patil

    2014-01-01

    Full Text Available 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 and divided into two groups treated with self ligating brackets (SLB, n=6 and conventional ligating brackets (CLB, n=6. The brackets used were 0.22 slot McLaughlin Bennet Trevesi (MBT prescription. Aligning was evaluated with 0.14 Niti followed by 19X25 Heat Activated Ni Ti and then 19X25 stainless steel wires for retraction within 4 months. The rate of retraction was evaluated per month and torque loss after space closure was also estimated. Results: Alignment Efficiency shows significant changes with SLB compared to CLB and also save more than 30% of chair side time during wire adjustments while rate of en masse retraction in SLB shows statistically non significance as compared to CLB system. In case of upper incisor changes when compared between two groups showed less torque loss in SLB than CLB although which was statistically no significant but % difference show SLB have better improvement result than CLB.

  19. Design of Engine Mount Bracket for a FSAE Car Using Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Jasvir Singh Dhillon

    2014-09-01

    Full Text Available Engine mounts have an important function of containing firmly the power-train components of a vehicle. Correct geometry and positioning of the mount brackets on the chassis ensures a good ride quality and performance. As an FSAE car intends to be a high performance vehicle, the brackets on the frame that support the engine undergo high static and dynamic stresses as well as huge amount of vibrations. Hence, dissipating the vibrational energy and keeping the stresses under a pre-determined level of safety should be achieved by careful designing and analysis of the mount brackets. Keeping this in mind the current paper discusses the modeling, Finite Element Analysis, Modal analysis and mass optimization of engine mount brackets for a FSAE car. As the brackets tend to undergo continuous vibrations and varying stresses, the fatigue strength and durability calculations also have been done to ensure engine safety.

  20. Precision forging technologies for magnesium alloy bracket and wheel

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Fundamental investigations on precision forging technology of magnesium alloys were studied. As-cast billet prestraining and a new concept of hollow billet were proposed in order to reduce the maximum forming load. A scheme of isothermal forming and the use of combined female dies were adopted, which can improve the die filling capacity and ensure the manufacture of high quality forgings. By means of the developed technique, AZ80 alloy wheel and AZ31 alloy bracket were produced successfully at suitable process parameters and applied in the automotive industries. The results show that the hot compression of AZ80 magnesium alloy has the peak flow stresses of pre-strained alloy with finer grain, which are lower by 20% than those of as-cast alloy under the same deformation conditions. The forming load is related to contact area and average positive stress on interface during forging process.

  1. On the compatible weakly nonlocal Poisson brackets of hydrodynamic type

    Directory of Open Access Journals (Sweden)

    Andrei Ya. Maltsev

    2002-01-01

    of hydrodynamic type (Ferapontov brackets and the corresponding integrable hierarchies. We show that, under the requirement of the nondegeneracy of the corresponding “first” pseudo-Riemannian metric g(0 νμ and also some nondegeneracy requirement for the nonlocal part, it is possible to introduce a “canonical” set of “integrable hierarchies” based on the Casimirs, momentum functional and some “canonical Hamiltonian functions.” We prove also that all the “higher” “positive” Hamiltonian operators and the “negative” symplectic forms have the weakly nonlocal form in this case. The same result is also true for “negative” Hamiltonian operators and “positive” symplectic structures in the case when both pseudo-Riemannian metrics g(0 νμ and g(1 νμ are nondegenerate.

  2. Evaluating the Type of Light Transmittance in Mono Crystalline, Poly Crystalline and Sapphire Brackets- An Invitro Spectrofluorometer Study

    Science.gov (United States)

    Kommi, Pradeep Babu; Kumar, M Senthil; Hanumanth; Venkatesan; Aniruddh; Arvinth; Kumar, Arani Nanda

    2016-01-01

    Introduction Most of the patients seek orthodontic treatment to improve the smile, which improves the facial profile by means of fixed appliances i.e., brackets and wires. The brackets are of different types like stainless steel and ceramic. Ceramic brackets were considered as aesthetic appliance which was divided into mono-crystalline, polycrystalline and sapphire brackets. The light transmittance might influence the degree of curing adhesive material in mono crystalline, polycrystalline and sapphire brackets. Aim The aim of the present study was to evaluate the translucency and intensity of three different aesthetic brackets (mono crystalline, poly crystalline and sapphire ceramic brackets) and to determine their influence on shear bond strength of the brackets. The adhesive remnant index was also measured after debonding of the brackets from the tooth surface. Materials and Methods Twenty six samples each of monocrystalline, polycrystalline and sapphire brackets (total 78 ceramic brackets) were used for the study. The bracket samples were subjected to optical fluorescence test using spectrofluorometer to measure the intensity of the brackets. Seventy eight extracted premolar teeth were procured and divided into 3 groups. The brackets were then bonded to the tooth using Transbond XT (3M Unitek) light cure composite material and cured with new light cure unit (Light Emitting Diode) of wood pecker company (400-450nm) for 30 seconds, and these samples were subjected to shear bond strength test with Instron Universal Testing Machine (UNITEK-94100) with a load range between 0 to 100 KN with a maximum cross head speed of 0.5mm/min. ARI (Adhesive Remnant Index) scores were evaluated according to Artun and Bergland scoring system using stereomicroscope at 20x magnification. Results The light absorption values obtained from spectrofluorometeric study were 3300000–3500000 cps for group 1 (monocrystalline ceramic brackets), 6000000–6500000 cps for Group 2

  3. Comparison of frictional resistance of esthetic and semi-esthetic self-ligating brackets

    Directory of Open Access Journals (Sweden)

    M S Kannan

    2015-01-01

    Full Text Available 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, which are of passive form and SEM (scanning electron microscope study of the Brackets after Frictional evaluation. Materials and Methods: Two types of self-ligating esthetic brackets, Damon clear (Ormco made of fully ceramic and Opal (Ultradent Products, USA and, Two types of self-ligating semi-esthetic brackets, Clarity SL (3M Unitek and Damon 3 (Ormco both of which are made of ceramic with metal slot. Arch wires with different dimensions and quality 17 × 25, 19 × 25 Titanium Molybdenum Alloy (TMA and 17 × 25, 19 × 25 stainless steel that came from plain strands of wire were used for frictional comparison test. The brackets used in this study had 0.022 × 0.028 inch slot. Results: The statistical tests showed significantly smaller amount of kinetic frictional forces is generated by Damon 3 (semi-esthetic self-ligating brackets. For each wire used, Damon 3 displayed significantly lower frictional forces (P ≤ 0.05 than any of the self-ligating system, followed by Opal (fully esthetic self-ligating brackets which generated smaller amount of frictional forces but relatively on the higher side when compared with Damon 3. Damon clear (fully esthetic self-ligating brackets generated the maximum amount of kinetic forces with all types of wire dimensions and properties when compared to the other three types of self-ligating system. Clarity SL (semi-esthetic self-ligating brackets generated smaller amount of frictional forces when compared with Damon clear and

  4. Shear bond strength of metallic brackets: influence of saliva contamination

    Directory of Open Access Journals (Sweden)

    Luciana Borges Retamoso

    2009-06-01

    Full Text Available OBJECTIVE: To evaluate the influence of saliva contamination on shear bond strength and the bond failure pattern of 3 adhesive systems (Transbond XT, AdheSE and Xeno III on orthodontic metallic brackets bonded to human enamel. MATERIAL AND METHODS: Seventy-two permanent human molars were cut longitudinally in a mesiodistal direction, producing seventy-two specimens randomly divided into six groups. Each system was tested under 2 different enamel conditions: no contamination and contaminated with saliva. In T, A and X groups, the adhesive systems were applied to the enamel surface in accordance with manufacturer's instructions. In TS, AS and XS groups, saliva was applied to enamel surface followed by adhesive system application. The samples were stored in distilled water at 37ºC for 24 h, and then tested for shear bond strength in a universal testing machine (Emic, DL 2000 running at a crosshead speed of 1 mm/min. After bond failure, the enamel surfaces were observed under an optical microscope at 40x magnification. RESULTS: The control and contaminated groups showed no significant difference in shear bond strength for the same adhesive system. However, shear bond strength of T group (17.03±4.91 was significantly higher than that of AS (8.58±1.73 and XS (10.39±4.06 groups (p<0.05. Regarding the bond failure pattern, TS group had significantly higher scores of no adhesive remaining on the tooth in the bonding area than other groups considering the adhesive remnant index (ARI used to evaluate the amount of adhesive left on the enamel. CONCLUSIONS: Saliva contamination showed little influence on the 24-h shear bond strength of orthodontic brackets.

  5. Opening and closure forces of sliding mechanisms of different self-ligating brackets

    Directory of Open Access Journals (Sweden)

    Paola GANDINI

    2013-06-01

    Full Text Available Self-ligating brackets engage the wire by means of a slide mechanism. Forces that have to be applied to open and close the sliding mechanism of brackets are still unknown. Objective The aim of this study was to measure and compare the opening and closure forces of different self-ligating brackets. Material and Methods Three different stainless steel self-ligating brackets (Carriere LX, Ortho Organizers; F1000, Leone; Damon Q, Ormco were tested. For each different bracket, 20 maxillary right central incisors and 20 mandibular right central incisors were used. Opening and closure forces were measured using an Instron Universal Testing Machine. Statistical analysis was performed and ANOVA and Tukey tests were carried out. Results Opening forces were registered between 1.1 N and 5.6 N, whereas closure forces were recorded between 1.57 N and 4.87 N. Significant differences were detected among the different brackets and between the two prescriptions tested. Conclusion The knowledge of different opening and closure forces of self-ligating brackets can help the orthodontist in the clinical management of these devices.

  6. A comparative study of metal artifacts from common metal orthodontic brackets in magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kajan, Zahra Dalili; Alizadeh, Ahmad; Hemmaty, Yasmin Babael; Roushan, Zahra Atrkar; Khademi, Jalil [Guilan University of Medical Sciences, Rasht (Iran, Islamic Republic of)

    2015-09-15

    This study was performed to compare the metal artifacts from common metal orthodontic brackets in magnetic resonance imaging. 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-echo T1-weighted images, fast spin-echo T2-weighted images, and fluid-attenuated inversion recovery images. In each sequence, the two sequential axial and coronal images with the largest signal-void area were selected. The largest diameters of the signal voids in the direction of the X-, Y-, and Z-axes were then measured twice. Finally, the mean linear values associated with different orthodontic brackets were analyzed using one-way analysis of variation, and the results were compared using the independent t-test to assess whether the use of SS or NiTi wires had a significant effect on the images. Statistically significant differences were only observed along the Z-axis among the four different brands of orthodontic brackets with SS wires. A statistically significant difference was observed along all axes among the brackets with NiTi wires. A statistically significant difference was found only along the Z-axis between nickel-free and nickel-containing brackets. With respect to all axes, the 3M bracket was associated with smaller signal-void areas. Overall, the 3M and Dentaurum brackets with NiTi wires induced smaller artifacts along all axes than those with SS wires.

  7. Poisson brackets of mappings obtained as ( q,- p) reductions of lattice equations

    Science.gov (United States)

    Tran, Dinh T.; van der Kamp, Peter H.; Quispel, G. R. W.

    2016-11-01

    In this paper, we present Poisson brackets of certain classes of mappings obtained as general periodic reductions of integrable lattice equations. The Poisson brackets are derived from a Lagrangian, using the so-called Ostrogradsky transformation. The ( q,- p) reductions are ( p + q)-dimensional maps and explicit Poisson brackets for such reductions of the discrete KdV equation, the discrete Lotka-Volterra equation, and the discrete Liouville equation are included. Lax representations of these equations can be used to construct sufficiently many integrals for the reductions. As examples we show that the (3,-2) reductions of the integrable partial difference equations are Liouville integrable in their own right.

  8. Torque expression of 0.018 and 0.022 inch conventional brackets.

    Science.gov (United States)

    Sifakakis, Iosif; Pandis, Nikolaos; Makou, Margarita; Eliades, Theodore; Katsaros, Christos; Bourauel, Christoph

    2013-10-01

    The aim of this study was to assess the effect of the moments generated with low- and high-torque brackets. Four different bracket prescription-slot combinations of the same bracket type (Mini Diamond® Twin) were evaluated: high-torque 0.018 and 0.022 inch and low-torque 0.018 and 0.022 inch. These brackets were bonded on identical maxillary acrylic resin models with levelled and aligned teeth and each model was mounted on the orthodontic measurement and simulation system (OMSS). Ten specimens of 0.017 × 0.025 inch and ten 0.019 × 0.025 inch stainless steel archwires (ORMCO) were evaluated in the low- and high-torque 0.018 inch and 0.022 inch brackets, respectively. The wires were ligated with elastomerics into the brackets and each measurement was repeated once after religation. Two-way analysis of variance and t-test were conducted to compare the generated moments between wires at low- and high-torque brackets separately. The maximum moment generated by the 0.017 × 0.025 inch stainless steel archwire in the 0.018 inch brackets at +15 degrees ranged from 14.33 and 12.95 Nmm for the high- and low-torque brackets, respectively. The measured torque in the 0.022 inch brackets with the 0.019 × 0.025 inch stainless steel archwire was 9.32 and 6.48 Nmm, respectively. The recorded differences of maximum moments between the high- and low-torque series were statistically significant. High-torque brackets produced higher moments compared with low-torque brackets. Additionally, in both high- and low-torque configurations, the thicker 0.019 × 0.025 inch steel archwire in the 0.022 inch slot system generated lower moments in comparison with the 0.017 × 0.025 inch steel archwire in the 0.018 inch slot system.

  9. Strength Analysis and Process Simulation of Subway Contact Rail Support Bracket of Composite Materials

    Science.gov (United States)

    Fedulov, Boris N.; Safonov, Alexander A.; Sergeichev, Ivan V.; Ushakov, Andrey E.; Klenin, Yuri G.; Makarenko, Irina V.

    2016-10-01

    An application of composites for construction of subway brackets is a very effective approach to extend their lifetime. However, this approach involves the necessity to prevent process-induced distortions of the bracket due to thermal deformation and chemical shrinkage. At present study, a process simulation has been carried out to support the design of the production tooling. The simulation was based on the application of viscoelastic model for the resin. Simulation results were verified by comparison with results of manufacturing experiments. To optimize the bracket structure the strength analysis was carried out as well.

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

    Institute of Scientific and Technical Information of China (English)

    Yan Xia ZHAO; Deng Yin WANG; Dong Fang JIA

    2011-01-01

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

  11. A Realization of Hom-Lie Algebras by Iso-Deformed Commutator Bracket

    OpenAIRE

    Xiuxian Li

    2013-01-01

    We construct classical Iso-Lie and Iso-Hom-Lie algebras in $gl(V)$ by twisted commutator bracket through Iso-deformation. We prove that they are simple. Their Iso-automorphisms and isotopies are also presented.

  12. Laser brackets debonding: Tm:YAP and ClarityTM SL self-ligating appliance system

    Science.gov (United States)

    Dostálová, Tatjana; Jelínková, Helena; Šulc, Jan; Koranda, Petr; Němec, Michal; Jelínek, Michal; Fibrich, Martin; Michalik, Pavel; Miyagi, Mitsunobu

    2010-02-01

    The study demonstrates the possibility of using Tm:YAP laser radiation for the removing ceramic brackets. The amount of enamel loss and residual resin on teeth has been evaluated. A diode-pumped Tm:YAP microchip laser generating at wavelength 1.9 μm was used for the debonding process. The transmission and absorption measurement of the basic elements - bracket, adhesive resin, and enamel was analyzed to explain the source of the heat and bracket debonding. Quantitative measurements are made for visualizing enamel surface before and after a self-ligating bonding technique. Temperature rise observation during the debonding procedure - from 0.5 to 2 W power - has improved the accuracy of assessment. The results were evaluated by CCD camera and scanning electron microscope. From the measurements it is possible to conclude that continuously running small diode pumped Tm:YAP microchip laser having output power 1W can remove the ceramic bracket without enamel iatrogenic damage.

  13. Biocompatibility of nanosilver-coated orthodontic brackets: an in vivo study

    Directory of Open Access Journals (Sweden)

    Gamze Metin-Gürsoy

    2016-12-01

    Full Text Available Abstract Background Nanosilver particles of which antibacterial and antifungal properties have been shown in various in vitro and in vivo studies are used in many medical and dental fields for the prevention of infection. In this study, it is intended to evaluate the biocompatibility of nanosilver-coated brackets. Methods Nanosilver coating process was applied to the standard orthodontic brackets by a physical vapor deposition system. Brackets were coated with nanosilver particles of 1 μ thickness. A total of 12 Wistar Albino rats were included in the study (six and control (six groups. For the study and control groups, four nanosilver-coated and four standard brackets were aseptically implanted subcutaneously in the dorsal region of each rat. The brackets were removed with the surrounding tissues on days 7, 14, 30, and 60. The specimens were evaluated for inflammatory response. Results No significant difference was found in terms of tissue reaction between the study and control groups. On day 7, randomly distributed brown-black granules were seen in the granulation tissue adjacent to the bracket in the study group. These foreign particles continued along the bracket cavity in a few samples, but the inflammatory response was insignificant between the groups. Mast cell count was found to be significantly smaller only on day 7 in the study group than in the control group. Conclusions Nanosilver-coated orthodontic brackets were found to be similar with the standard type concerning inflammation. Further researches are needed with regard to the assessment of the brown-black granules, especially on the deposition of the vessel walls.

  14. Canonical form of Nambu–Poisson bracket: A pedestrian approach

    Indian Academy of Sciences (India)

    S K Soni; Swami Nandan

    2011-12-01

    In the seventies, Nambu (Phys. Rev. D7, 2405 (1973)) proposed a new approach to classical dynamics based on an -dimensional Nambu–Poisson (NP) manifold replacing the primitive even-dimensional Poisson manifold and on –1 Hamiltonians in place of a single Hamiltonian. This approach has had many promoters including Bayen and Flato (Phys. Rev. D11, 3049 (1975)), Mukunda and Sudarshan (Phys. Rev. D13, 2846 (1976)), and Takhtajan (Comm. Math. Phys. 160, 295 (1994)) among others. While Nambu had originally considered = 3, the illustration of his ideas for = 4 and 6 was given by Chatterjee (Lett. Math. Phys. 36, 117 (1996)) who observed that the classical description of dynamical systems having dynamical symmetries is described elegantly by Nambu’s formalism of mechanics. However, his considerations do not quite yield the beautiful canonical form conjectured by Nambu himself for the -ary NP bracket. By making a judicious choice for the ‘extra constant of motion’ of namely, and , which are the orientation angles in Kepler problem and isotropic harmonic oscillator (HO) respectively, we show that the dynamical systems with dynamical symmetries can be recast in the beautiful form suggested by Nambu. We believe that the techniques used and the theorems suggested by us in this work are of general interest because of their involvement in the transition from Hamiltonian mechanics to Nambu mechanics.

  15. Mechanical and topographic evaluation of esthetic brackets and its relation to frictional resistance

    Directory of Open Access Journals (Sweden)

    Vikram Pai

    2013-01-01

    Full Text Available Introduction: The purpose of this in-vitro study was to evaluate the frictional characteristics of conventional ceramic versus metal insert ceramic brackets in combination with stainless steel and Teflon-coated stainless steel archwires. Materials and Methods: Twenty brackets each, of ceramic and metal insert ceramic Maxillary canine preadjusted edgewise brackets 0.022 × 0.028 in slot and 20 archwires, each of stainless steel and Teflon-coated stainless steel (0.019 × 0.025 in were tested for frictional resistance. Friction was evaluated in a simulated Tidy′s design apparatus on universal testing machine. The kinetic friction data were analyzed using Student′s ′t′ test. The effects of surface characteristics on frictional resistance were qualitatively assessed using scanning electron microscope. Results: Metal insert ceramic brackets generated significantly lower kinetic frictional resistance than the conventional ceramic brackets with Teflon-coated stainless steel archwires (P < 0.001 as well as stainless steel archwires (P < 0.05. Conclusion: Metal insert ceramic bracket with stainless steel archwire is the best possible combination among the materials studied because it generated the least frictional resistance during simulated tooth movement.

  16. Evaluation of force released by deflection of orthodontic wires in conventional and self-ligating brackets

    Directory of Open Access Journals (Sweden)

    Rodrigo Hitoshi Higa

    Full Text Available ABSTRACT Introduction: The aim of the study was to evaluate deflection forces of rectangular orthodontic wires in conventional (MorelliTM, active (In-Ovation RTM and passive (Damon 3MXTM self-ligating brackets. Material and Methods: Two brands of stainless steel and nickel-titanium (NiTi wires (MorelliTM and GACTM, in addition to OrmcoTM copper-nickel-titanium wires were used. Specimens were assembled in a clinical simulation device especially designed for this study and tested in an Instron universal testing machine. For the testing procedures, an acrylic structure representative of the maxillary right central incisor was lingually moved in activations of 0 to 1 mm, with readings of the force released by deflection in unloading of 0.5, 0.8 and 1 mm at a constant speed of 2 mm/min. Inter-bracket forces with stainless steel, NiTi and CuNiTi were individually compared by two-way ANOVA, followed by Tukey’s tests. Results: Results showed that there were lower forces in conventional brackets, followed by active and passive self-ligating brackets. Within the brands, only for NiTi wires, the MorelliTM brand presented higher forces than GACTM wires. Conclusions: Bracket systems provide different degrees of deflection force, with self-ligating brackets showing the highest forces.

  17. Evaluation of force released by deflection of orthodontic wires in conventional and self-ligating brackets

    Science.gov (United States)

    Higa, Rodrigo Hitoshi; Semenara, Nayara Thiago; Henriques, José Fernando Castanha; Janson, Guilherme; Sathler, Renata; Fernandes, Thais Maria Freire

    2016-01-01

    ABSTRACT Introduction: The aim of the study was to evaluate deflection forces of rectangular orthodontic wires in conventional (MorelliTM), active (In-Ovation RTM) and passive (Damon 3MXTM) self-ligating brackets. Material and Methods: Two brands of stainless steel and nickel-titanium (NiTi) wires (MorelliTM and GACTM), in addition to OrmcoTM copper-nickel-titanium wires were used. Specimens were assembled in a clinical simulation device especially designed for this study and tested in an Instron universal testing machine. For the testing procedures, an acrylic structure representative of the maxillary right central incisor was lingually moved in activations of 0 to 1 mm, with readings of the force released by deflection in unloading of 0.5, 0.8 and 1 mm at a constant speed of 2 mm/min. Inter-bracket forces with stainless steel, NiTi and CuNiTi were individually compared by two-way ANOVA, followed by Tukey’s tests. Results: Results showed that there were lower forces in conventional brackets, followed by active and passive self-ligating brackets. Within the brands, only for NiTi wires, the MorelliTM brand presented higher forces than GACTM wires. Conclusions: Bracket systems provide different degrees of deflection force, with self-ligating brackets showing the highest forces. PMID:28125144

  18. Influence of ligation method on friction resistance of lingual brackets with different second-order angulations: an in vitro study

    Science.gov (United States)

    Pereira, Graziane Olímpio; Gimenez, Carla Maria Melleiro; Prieto, Lucas; Prieto, Marcos Gabriel do Lago; Basting, Roberta Tarkany

    2016-01-01

    ABSTRACT Objective: To evaluate stainless steel archwire static friction in active and passive self-ligating lingual and conventional brackets with second-order angulations. Methods: Two conventional lingual brackets for canines (STb light/Ormco; PSWb/Tecnident), and two self-ligating brackets, one active (In-Ovation L/GAC) and the other passive (3D/ Forestadent), were evaluated. A stainless steel archwire was used at 0°, 3° and 5° angulations. Metal ligatures, conventional elastic ligatures, and low friction elastic ligatures were also tested. A universal testing machine applied friction between brackets and wires, simulating sliding mechanics, to produce 2-mm sliding at 3 mm/minute speed. Results: Two-way analysis of variance demonstrated a significant effect of the interaction between brackets and angulations (p < 0.001). Tukey test indicated that the highest frictional resistance values were observed at 5° angulation for In-Ovation L, PSWb bracket with non conventional ligature, and STb bracket with metal ligature. As for 3D, PSWb with conventional or metal ligatures, and STb brackets with non conventional ligature, showed significantly lower static frictional resistance with 0° angulation. At 0° angulation, STb brackets with metal ties, In-Ovation L brackets and 3D brackets had the lowest frictional resistance. Conclusions: As the angulation increased from 0° to 3°, static friction resistance increased. When angulation increased from 3° to 5°, static friction resistance increased or remained the same. Self-ligating 3D and In-Ovation L brackets, as well as conventional STb brackets, seem to be the best option when sliding mechanics is used to perform lingual orthodontic treatment. PMID:27653262

  19. Shear bond strength of orthodontic brackets to enamel under different surface treatment conditions

    Directory of Open Access Journals (Sweden)

    Matheus Melo Pithon

    2007-04-01

    Full Text Available The purpose of the present study was to evaluate the shear bond strength to enamel and the adhesive remnant index (ARI of both metallic and polycarbonate brackets bonded under different conditions. Ninety bovine permanent mandibular incisors were embedded in acrylic resin using PVC rings as molds and assigned to 6 groups (n=15. In Groups 1 (control and 3, metallic and polycarbonate orthodontic brackets were, respectively, bonded to the enamel surfaces using Transbond XT composite according to the manufacturer's recommendations. In Groups 2 and 4, both types of brackets were bonded to enamel with Transbond XT composite, but XT primer was replaced by the OrthoPrimer agent. In Groups 5 and 6, the polycarbonate bracket bases were sandblasted with 50-mm aluminum-oxide particle stream and bonded to the enamel surfaces prepared under the same conditions described in Groups 3 and 4, respectively. After bonding, the specimens were stored in distilled water at 37ºC for 24 hours and then submitted to shear bond strength test at a crosshead speed of 0.5 mm/min. The results (MPa showed no statistically significant difference between Groups 4 and 6 (p>0.05. Likewise, no statistically significant differences (p>0.05 were found among Groups 1, 2, and 5, although their results were significantly lower than those of Groups 4 and 6 (p<0.05. Group 3 had statistically significant lower bond strength than Groups 2, 4, and 6, but no statistically significant differences were found on comparison to Groups 1 and 5. A larger number of fractures at the bracket/composite interface were evidenced by the ARI scores. OrthoPrimer bonding agent yielded higher bond strength in the groups using either conventional or sandblasted polycarbonate brackets, which was not observed in the groups using metallic brackets.

  20. Comparison of Bond Strength of Metal and Ceramic Brackets Bonded with Conventional and High-Power LED Light Curing Units

    Science.gov (United States)

    Chalipa, Javad; Jalali, Yasamin Farajzadeh; Gorjizadeh, Fatemeh; Baghaeian, Pedram; Hoseini, Mohammad Hashem

    2016-01-01

    Objectives: The aim of this study was to evaluate the effect of conventional and high-power light emitting diode (LED) light curing units on shear bond strength (SBS) of metal and ceramic brackets to tooth surface. Materials and Methods: Forty sound bovine maxillary central incisors were used for the study. The teeth were divided into four groups (n=10). Teeth surfaces were etched with 37% phosphoric acid for 20 seconds. After applying a uniform layer of adhesive primer on the etched enamel, composite was placed on the base of brackets. The samples were light cured according to the manufacturer’s instructions and thermocycled. The SBS was measured. The failure mode was scored using the adhesive remnant index (ARI). Results: The mean SBS of samples in groups A (high-power LED, metal bracket), B (high-power LED, ceramic bracket), C (conventional LED, metal bracket) and D (conventional LED, ceramic bracket) was 23.1±3.69, 10.7±2.06, 24.92±6.37 and 10.74±3.18MPa, respectively. The interaction effect of type of LED unit (high-power/conventional) and bracket type on SBS was not statistically significant (P=0.483). In general, type of LED unit did not affect SBS. Type of bracket significantly affected SBS (P<0.001). The ARI score was not significantly influenced by the interaction between the type of LED unit and bracket. Conclusions: The obtained SBS is the same for both bracket types by use of high-power and conventional LED light curing units. Regardless of the type of LED unit, SBS of ceramic brackets was significantly lower than that of metal brackets.

  1. Evaluation of shear bond strength of metallic and ceramic brackets bonded to enamel prepared with self-etching primer.

    Science.gov (United States)

    Uysal, Tancan; Ustdal, Ayca; Kurt, Gokmen

    2010-04-01

    The aim of this in vitro study was to evaluate the shear bond strength (SBS) of different metallic and ceramic bracket bonding combinations using self-etching primers (SEPs). Eighty freshly extracted human premolar teeth were randomly divided into four equal groups for bonding with ceramic or metallic brackets as follows: group 1, metallic brackets bonded with conventional acid etching; group 2, metallic brackets bonded with Transbond Plus Self-Etching primer (TPSEP); group 3, ceramic brackets bonded as per group 1; group 4, ceramic brackets bonded as per group 2. The SBS of these brackets was measured and recorded in megapascals (MPa). The adhesive remnant index (ARI) scores were determined after bracket failure. Data were analyzed with the analysis of variance, Tukey, and chi-square tests. The bond strength of group 3 (mean: 36.7 +/- 11.8 MPa) was significantly higher than group 4 (mean: 26.6 +/- 8.9 MPa; P 0.05). Compared with conventional acid etching, SEPs significantly decreased the SBS of ceramic orthodontic brackets.

  2. Shear bond strength of ceramic and metallic orthodontic brackets bonded with self-etching primer and conventional bonding adhesives

    Science.gov (United States)

    Arash, Valiollah; Naghipour, Fatemeh; Ravadgar, Mehdi; Karkhah, Ahmad; Barati, Mohammad Saleh

    2017-01-01

    Introduction Adult patients typically require high-quality orthodontic treatment for ceramic brackets, but some clinicians remain concerned about the bond strength of these brackets. Therefore, the aim of this study was to determine the shear bond strength and de-bonding characteristics of metallic and ceramic brackets bonded with two types of bonding agents. Methods In an experimental study done in 2013 in Babol, Iran, 120 extracted human maxillary premolar teeth were randomly divided into four groups as follows: HM group: metallic bracket/conventional bonding agent; SM group: metallic bracket/Transbond self-etching primer; HC group: ceramic bracket/conventional bonding agent; SC group: ceramic bracket/Transbond self-etching primer. Twenty-four hours after thermocycling (1000 cycle, 5 °C–55 °C), the shear bond strength values were measured. The amount of resin remaining on the tooth surface (adhesive remnant index: ARI) was determined under a stereomicroscope. Enamel detachment index was evaluated under a scanning electron microscope. To perform statistical analysis, ANOVA, Kruskal–Wallis, and Tukey post-hoc tests were applied. The level of significance was set at p ceramic brackets. In addition, self-etching primer was able to produce fewer bonds compared with the conventional technique. Many samples showed the bracket-adhesive interface failure or failure inside the adhesive. PMID:28243410

  3. A method for producing controlled fluoride release from an orthodontic bracket.

    Science.gov (United States)

    Li, Song; Hobson, Ross S; Bai, Yuxing; Yan, Zhuoqun; Carrick, Thomas E; McCabe, John F

    2007-12-01

    The aim of this study was to manufacture and test, in vitro, a novel modification to provide fluoride-releasing orthodontic brackets. Thirty-two orthodontic brackets were drilled to produce a recess (approximately 1.3 mm in diameter and 0.7 mm in depth) at the centre of the bracket base. Four materials, with and without the addition of sodium fluoride, a glass ionomer cement (Ketac Cem micro), a resin-modified glass ionomer cement (RMGIC; GC Fuji Ortho LC), a zinc phosphate (Zinc Cement Improved), and a resin (Transbond XT) were used to fill the recess in the bracket base. Fluoride release was measured daily during the first week and then weekly for 10 weeks. An ion chromatograph with suppressed conductivity was used for free fluoride ion determination. Statistical analysis to determine the amount of flouride release was undertaken using analysis of variance and Tukey's test. During the first 2 weeks, the resin group, with the addition of 38 per cent sodium fluoride added, released significantly more free fluoride (P < 0.05), but after 2 weeks the fluoride release markedly decreased. After 5 weeks, the RMGIC group, with 15 per cent added sodium fluoride, had significantly higher (P < 0.05) daily fluoride release than the other groups. The findings demonstrated that an appropriate fluoridated material can be used as a fluoride-releasing reservoir in a modified orthodontic bracket to enable it to release fluoride over the period of fixed appliance treatment.

  4. Effect of Four Methods of Surface Treatment on Shear Bond Strength of Orthodontic Brackets to Zirconium

    Science.gov (United States)

    Yassaei, Soghra; Aghili, Hossein Agha; Davari, Abdolrahim

    2015-01-01

    Objectives: Providing reliable attachment between bracket base and zirconia surface is a prerequisite for exertion of orthodontic force. The purpose of the present study was to evaluate the effect of four zirconium surface treatment methods on shear bond strength (SBS) of orthodontic brackets. Materials and Methods: One block of zirconium was trimmed into four zirconium surfaces, which served as our four study groups and each had 18 metal brackets bonded to them. Once the glazed layer was removed, the first group was etched with 9.6% hydrofluoric acid (HF), and the remaining three groups were prepared by means of sandblasting and 1W, and 2W Er: YAG laser, respectively. After application of silane, central incisor brackets were bonded to the zirconium surfaces. The SBS values were measured by a Dartec testing machine with a crosshead speed of 1 mm/min. Data were analyzed using one-way ANOVA and Tukey’s HSD for multiple comparisons. Results: The highest SBS was achieved in the sandblasted group (7.81±1.02 MPa) followed in a descending order by 2W laser group (6.95±0.87 MPa), 1W laser group (6.87±0.92 MPa) and HF acid etched group (5.84±0.78 MPa). The differences between the study groups were statistically significant except between the laser groups (Pacid etching for zirconium surface treatment prior to bracket bonding. PMID:26622283

  5. Influence of lingual bracket position on microbial and periodontal parameters in vivo

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    Maria Francesca Sfondrini

    2012-06-01

    Full Text Available OBJECTIVE: Lingual orthodontics is becoming more popular in dental practice. The purpose of the present investigation was to compare plaque formation on teeth bonded with the same bracket onto buccal or lingual surface, with non-bonded control teeth, via an in vivo growth experiment over a 30-day period. MATERIAL AND METHODS: A randomized controlled trial with split-mouth design was set up enrolling 20 dental students. Within each subject sites with buccal and lingual brackets and control sites were followed. Clinical periodontal parameters (periodontal pocket depth: PPD; bleeding on probing: BOP were recorded at baseline and on days 1, 7 and 30. Microbiological samples were taken from the brackets and the teeth on days 1, 7 and 30 to detect colony-forming units (CFU. Total CFU, streptococci CFU and anaerobe CFU were measured. RESULTS: No significant differences (P>0.05 were found between buccal and lingual brackets in terms of clinical periodontal parameters and microbiological values. Conclusion: Bracket position does not have significant impact on bacterial load and on periodontal parameters.

  6. Evaluation of Antibacterial Effects of Silver-Coated Stainless Steel Orthodontic Brackets

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    Valiollah Arash

    2016-08-01

    Full Text Available Objectives: White spots and enamel demineralization around orthodontic brackets are among the most important complications resulting from orthodontic treatments. Since the antibacterial properties of metals and metallic particles have been well documented, the aim of this study was to assess the antibacterial effect of stainless steel orthodontic brackets coated with silver (Ag particles.Materials and Methods: In this study, 40 standard metal brackets were divided into two groups of 20 cases and 20 controls. The brackets in the case group were coated with Ag particles using an electroplating method. Atomic force microscopy (AFM and scanning electron microscopy (SEM were used to assess the adequacy of the coating process. In addition, antibacterial tests, i.e., disk diffusion and direct contact tests were performed at three, six, 24and 48 hours, and 15 and 30 days using a Streptococcus mutans strain. The results were analyzed using Student’s t-test and repeated measures ANOVA.Conclusions: Brackets coated with Ag, via an electroplating method, exhibited antibacterial properties when placed in direct contact with Streptococcus mutans. This antibacterial effect persisted for 30 days after contact with the bacteria.

  7. Effect of Adhesive Type on the Shear Bond Strength of Metal Brackets to Two Ceramic Substrates

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    Mohammad Sadegh Ahmad Akhoundi

    2014-04-01

    Full Text Available Increased number of adult patients requesting orthodontic treatment result in bonding bracket to ceramic restorations more than before. The aim of this study was to evaluate and compare the shear bond strength of orthodontic brackets bonded to two types of ceramic bases with conventional orthodontic bonding resin and a new nano-filled composite resin.Twenty four feldespathic porcelain and 24 lithium disilicate ceramic disks were fabricated. All of the samples were conditioned by sandblasting, hydrofluoric acid and silane. Maxillary incisor metal brackets were bonded to half of the disks in each group by conventional orthodontic bonding resin and the other half bonded with a nano-filled composite. The samples then were thermocycled for 2000 cycle between 5-55° C. Shear bond strength was measured and the mode of failure was examined. Randomly selected samples were also evaluated by SEM.The lowest bond strength value was found infeldespathic ceramic bonded by nano-filled composite (p<0.05. There was not any statistically significant difference between other groups regarding bond strength. The mode of failure in the all groups except group 1 was cohesive and porcelain damages were detected.Since less damages to feldspathic porcelain was observed when the nano-filled composite was used to bond brackets, the use of nano-filled composite resins can be suggested for bonding brackets to feldspathic porcelain restorations.

  8. In vitro analysis of shear bond strength and adhesive remnant index of different metal brackets

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    Fernanda de Souza Henkin

    Full Text Available ABSTRACT Introduction: There is a great variety of orthodontic brackets in the Brazilian market, and constantly evaluating them is critical for professionals to know their properties, so as to be able to choose which product best suits their clinical practice. Objectives: To evaluate the bond strength and the adhesive remnant index (ARI of different brands of metal brackets. Material and Methods: A total of 105 bovine incisors were used, and brackets of different brands were bonded to teeth. Seven different bracket brands were tested (MorelliTM, American OrthodonticsTM, TP OrthodonticsTM, Abzil-3MTM, OrthometricTM, TecnidentTM and UNIDENTM. Twenty-four hours after bonding, shear bond strength test was performed; and after debonding, the ARI was determined by using an optical microscope at a 10-fold increase. Results: Mean shear bond strength values ranged from 3.845 ± 3.997 (MorelliTM to 9.871 ± 5.106 MPa (TecnidentTM. The majority of the ARI index scores was 0 and 1. Conclusion: Among the evaluated brackets, the one with the lowest mean shear bond strength values was MorelliTM. General evaluation of groups indicated that a greater number of bond failure occurred at the enamel/adhesive interface.

  9. In vitro analysis of shear bond strength and adhesive remnant index of different metal brackets

    Science.gov (United States)

    Henkin, Fernanda de Souza; de Macêdo, Érika de Oliveira Dias; Santos, Karoline da Silva; Schwarzbach, Marília; Samuel, Susana Maria Werner; Mundstock, Karina Santos

    2016-01-01

    ABSTRACT Introduction: There is a great variety of orthodontic brackets in the Brazilian market, and constantly evaluating them is critical for professionals to know their properties, so as to be able to choose which product best suits their clinical practice. Objectives: To evaluate the bond strength and the adhesive remnant index (ARI) of different brands of metal brackets. Material and Methods: A total of 105 bovine incisors were used, and brackets of different brands were bonded to teeth. Seven different bracket brands were tested (MorelliTM, American OrthodonticsTM, TP OrthodonticsTM, Abzil-3MTM, OrthometricTM, TecnidentTM and UNIDENTM). Twenty-four hours after bonding, shear bond strength test was performed; and after debonding, the ARI was determined by using an optical microscope at a 10-fold increase. Results: Mean shear bond strength values ranged from 3.845 ± 3.997 (MorelliTM) to 9.871 ± 5.106 MPa (TecnidentTM). The majority of the ARI index scores was 0 and 1. Conclusion: Among the evaluated brackets, the one with the lowest mean shear bond strength values was MorelliTM. General evaluation of groups indicated that a greater number of bond failure occurred at the enamel/adhesive interface. PMID:28125142

  10. Efficacy of quercetin flavonoid in recovering the postbleaching bond strength of orthodontic brackets: A preliminary study

    Science.gov (United States)

    Shamsedin, Mana; Arash, Valiollah; Jahromi, Masoud Babaei; Moghadamnia, Ali Akbar; Kamel, Manouchehr Rahmati; Ezoji, Fariba; bijani, Ali; Kavoli, Samira; Ghasemi, Tania; Ramezani, Gholamhossein

    2017-01-01

    Objectives: To evaluate comparatively the effect of quercetin on postbleaching shear bond strength (SBS) and adhesive remnant index (ARI). Materials and Methods: Intact maxillary premolars were divided randomly into 12 groups of 10 each: (1) bonding the bracket immediately after bleaching, (2) bonding 1 week after bleaching, (3–8) application of three experimental concentrations of quercetin (0.1%, 0.5%, and 1%) at two time durations (5 and 10 min), (9–10) application of the solvent of quercetin at two time periods (5 and 10 min), (11) application of 10% sodium ascorbate for 10 min, and (12) bonding the brackets on nonbleached teeth. Bleaching was performed using 15% carbamide peroxide gel for 5 days (6 h daily). After incubation and thermocycling, the SBS of brackets was measured. The ARI too was recorded at ×20. The data were analyzed statistically (α =0.05). Results: Bleaching reduced the SBS below 10 Megapascal (MPa) level (P 0.01). All eight postbleaching treatments had rather similar efficacies (P = 0.1396). The concentration of quercetin (beta = 0.259, P = 0.042) but not its duration (beta = 0.213, P = 0.093) significantly improved its efficacy. Conclusion: Bleaching can weaken the bond strength of orthodontic brackets below acceptable levels. The application of quercetin or Vitamin C or delaying the bracket bonding improved the postbleaching SBS. PMID:28197398

  11. The effect of enamel bleaching on the shear bond strengths of metal and ceramic brackets.

    Science.gov (United States)

    Oztaş, E; Bağdelen, G; Kiliçoğlu, H; Ulukapi, H; Aydin, I

    2012-04-01

    The aim of this study was to evaluate the effects of bleaching and delayed bonding on the shear bond strengths of metal and ceramic brackets bonded with light and chemically cure composite resin to human enamel. One hundred and twenty extracted human premolar teeth were randomly divided into three groups of 40 each. The first two groups were bleached with 20 per cent carbamide peroxide (CP) at-home bleaching agent. No bleaching procedures were applied to the third group and served as control. The first two and control groups were divided into equal subgroups according to different adhesive-bracket combinations. Specimens in group 1 (n = 40) were bonded 24 hours after bleaching process was completed while the specimens in group 2 (n = 40) were bonded 14 days after. The specimens in all groups were debonded with a Universal testing machine while the modified adhesive remnant index was used to evaluate fracture properties. No statistically significant differences were found between the shear bond strengths of metal and ceramic brackets bonded to bleached enamel after 24 hours, 14 days, and unbleached enamel with light or chemical cure adhesives (P > 0.05). The mode of failure was mostly at the bracket/adhesive interface and cohesive failures within the resin were also observed. Our findings indicated that at-home bleaching agents that contain 20 per cent CP did not significantly affect the shear bond strength of metal and ceramic orthodontic brackets to enamel when bonding is performed 24 hours or 14 days after bleaching.

  12. Occurrence and severity of enamel decalcification adjacent to bracket bases and sub-bracket lesions during orthodontic treatment with two different lingual appliances

    Science.gov (United States)

    Klang, Elisabeth; Helms, Hans-Joachim; Wiechmann, Dirk

    2016-01-01

    Summary Background: Using lingual enamel surfaces for bracket placement not only has esthetic advantages, but may also be suitable in terms of reducing frequencies of enamel decalcifications. Objective: To test the null-hypothesis that there is no significant difference in enamel decalcification or cavitation incidence adjacent to and beneath bracket bases between two lingual multi-bracket (MB) appliances that are different in terms of design, material composition, and manufacturing technology (group A: WIN, DW-LingualSystems; group B: Incognito, 3M-Unitek), taking into account patient- and treatment-related variables on white spot lesion (WSL) formation. Methods: Standardized, digital, top-view photographs of 630 consecutive subjects (16214 teeth; n Incognito = 237/6076 teeth; n WIN = 393/10138 teeth; mean age: 17.47±7.8; m/f 43.2/56.8%) with completed lingual MB treatment of the upper and lower permanent teeth 1–7 were screened for decalcification or cavitation adjacent to and beneath the bracket bases before and after treatment, scored from 0 to 7. Non-parametric ANOVA was used for main effects ‘appliance type’, ‘gender’, ‘treatment complexity’, ‘grouped age’ (≤16/>16 years), and ‘treatment duration’ as covariable, at an α-level of 5%. Results: About 2.57% [5.94%] of all teeth in group A [B] developed decalcifications. Subject-related incidence was 9.59% [16.17%] for upper incisors in group A [B], and 12.98% [25.74%] for all teeth 16–46. There were significant effects by gender, age, and treatment duration. Conclusion: The null-hypothesis was rejected: sub-bracket lesions were significantly less frequent in group A, while frequencies of WSL adjacent to brackets were not significantly affected by appliance type. In view of the overall low incidences of lingual post-orthodontic white-spot lesions, the use of lingual appliances is advocated as a valid strategy for a reduction of enamel decalcifications during orthodontic treatment. PMID

  13. Simulation and experimental validation of powertrain mounting bracket design obtained from multi-objective topology optimization

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    Qinghai Zhao

    2015-06-01

    Full Text Available A framework of multi-objective topology optimization for vehicle powertrain mounting bracket design with consideration of multiple static and dynamic loading conditions is developed in this article. Incorporating into the simplified isotropic material with penalization model, compromise programming method is employed to describe the multi-objective and multi-stiffness topology optimization under static loading conditions, whereas mean eigenvalue formulation is proposed to analyze vibration optimization. To yield well-behaved optimal topologies, minimum member size and draw constraint are settled for meeting manufacturing feasibility requirements. The ultimate mounting bracket is reconstructed based on the optimum results. Numerical analyses of the bracket are performed, followed by physical tests. It is proven that topology optimization methodology is promising and effective for vehicle component design.

  14. Effects of delayed polymerization time and bracket manipulation on orthodontic resin modified glass ionomer adhesive

    Science.gov (United States)

    Gilbert, Danielle Wiggins

    This study examined the effect of varying delayed polymerization times in combination with bracket manipulation on shear bond strength (SBS), degree of conversion (DC), and adhesive remnant index (ARI) score when using a resin modified glass ionomer (RMGI) adhesive. Specimens were divided into three groups of clinically relevant delay times (0.5, 2, and 4-min) to simulate the delay that frequently occurs between bracket placement and manipulation and subsequent light curing. Based on an analysis of variance (alpha=.05), the SBS was not significantly different between the three groups. While one of the goals of this study was to be the first study to quantify DC of RMGI using Raman microspectroscopy, several challenges, including weak peak signal with and without fluorescence, were encountered and as a result, DC could not be determined. A significant difference (p<0.05) in ARI score was detected between the 0.5-min and 4.0-min delay groups with more adhesive remaining on the bracket with increasing delay time. A Spearman correlation between SBS and ARI indicated no positive association between SBS and ARI measures across delay times. The results of this study suggest that clinically relevant delay times of 0.5, 2, and 4-min do not negatively impact the SBS of a RMGI adhesive. However, with increasing delay time, the results suggest that more adhesive might remain on the bracket during debonding. With more adhesive remaining on the bracket, this could be beneficial in that less adhesive needs to be removed from enamel by grinding at the time of bracket removal when orthodontic treatment is completed.

  15. Assessment of dimensional accuracy of preadjusted metal injection molding orthodontic brackets

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    Shiva Alavi

    2016-01-01

    Full Text Available Background: the aim of this study is to evaluate the dimensional accuracy of McLaughlin, Bennett, and Trevisi (MBT brackets manufactured by two different companies (American Orthodontics and Ortho Organizers and determine variations in incorporation of values in relation to tip and torque in these products. Materials and Methods: In the present analytical/descriptive study, 64 maxillary right central brackets manufactured by two companies (American Orthodontics and Ortho Organizers were selected randomly and evaluated for the accuracy of the values in relation to torque and angulation presented by the manufacturers. They were placed in a video measuring machine using special revolvers under them and were positioned in a manner so that the light beams would be directed on the floor of the slot without the slot walls being seen. Then, the software program of the same machine was used to determine the values of each bracket type. The means of measurements were determined for each sample and were analyzed with independent t-test and one-sample t-test. Results: Based on the confidence interval, it can be concluded that at 95% probability, the means of tip angles of maxillary right central brackets of these two brands were 4.1-4.3° and the torque angles were 16.39-16.72°. The tips in these samples were at a range of 3.33-4.98°, and the torque was at a range of 15.22-18.48°. Conclusion: In the present study, there were no significant differences in the angulation incorporated into the brackets from the two companies; however, they were significantly different from the tiP values for the MBT prescription. In relation to torque, there was a significant difference between the American Orthodontic brackets exhibited significant differences with the reported 17°, too.

  16. Assessment of dimensional accuracy of preadjusted metal injection molding orthodontic brackets

    Science.gov (United States)

    Alavi, Shiva; Tajmirriahi, Farnaz

    2016-01-01

    Background: the aim of this study is to evaluate the dimensional accuracy of McLaughlin, Bennett, and Trevisi (MBT) brackets manufactured by two different companies (American Orthodontics and Ortho Organizers) and determine variations in incorporation of values in relation to tip and torque in these products. Materials and Methods: In the present analytical/descriptive study, 64 maxillary right central brackets manufactured by two companies (American Orthodontics and Ortho Organizers) were selected randomly and evaluated for the accuracy of the values in relation to torque and angulation presented by the manufacturers. They were placed in a video measuring machine using special revolvers under them and were positioned in a manner so that the light beams would be directed on the floor of the slot without the slot walls being seen. Then, the software program of the same machine was used to determine the values of each bracket type. The means of measurements were determined for each sample and were analyzed with independent t-test and one-sample t-test. Results: Based on the confidence interval, it can be concluded that at 95% probability, the means of tip angles of maxillary right central brackets of these two brands were 4.1–4.3° and the torque angles were 16.39–16.72°. The tips in these samples were at a range of 3.33–4.98°, and the torque was at a range of 15.22–18.48°. Conclusion: In the present study, there were no significant differences in the angulation incorporated into the brackets from the two companies; however, they were significantly different from the tiP values for the MBT prescription. In relation to torque, there was a significant difference between the American Orthodontic brackets exhibited significant differences with the reported 17°, too. PMID:27857770

  17. Qualitative Research of AZ31 Magnesium Alloy Aircraft Brackets Produced by a New Forging Method

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    Dziubińska A.

    2016-06-01

    Full Text Available The paper reports a selection of numerical and experimental results of a new closed-die forging method for producing AZ31 magnesium alloy aircraft brackets with one rib. The numerical modelling of the new forming process was performed by the finite element method.The distributions of stresses, strains, temperature and forces were examined. The numerical results confirmed that the forgings produced by the new forming method are correct. For this reason, the new forming process was verified experimentally. The experimental results showed good agreement with the numerical results. The produced forgings of AZ31 magnesium alloy aircraft brackets with one rib were then subjected to qualitative tests.

  18. Whitham's Method and Dubrovin-Novikov Bracket in Single-Phase and Multiphase Cases

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    Andrei Ya. Maltsev

    2012-12-01

    Full Text Available In this paper we examine in detail the procedure of averaging of the local field-theoretic Poisson brackets proposed by B.A. Dubrovin and S.P. Novikov for the method of Whitham. The main attention is paid to the questions of justification and the conditions of applicability of the Dubrovin-Novikov procedure. Separate consideration is given to special features of single-phase and multiphase cases. In particular, one of the main results is the insensitivity of the procedure of bracket averaging to the appearance of ''resonances'' which can arise in the multi-phase situation.

  19. The noncommutative Poisson bracket and the deformation of the family algebras

    Science.gov (United States)

    Wei, Zhaoting

    2015-07-01

    The family algebras are introduced by Kirillov in 2000. In this paper, we study the noncommutative Poisson bracket P on the classical family algebra 𝒞τ(𝔤). We show that P controls the first-order 1-parameter formal deformation from 𝒞τ(𝔤) to 𝒬τ(𝔤) where the latter is the quantum family algebra. Moreover, we will prove that the noncommutative Poisson bracket is in fact a Hochschild 2-coboundary, and therefore, the deformation is infinitesimally trivial. In the last part of this paper, we discuss the relation between Mackey's analogue and the quantization problem of the family algebras.

  20. Does It Help to Use Mathematically Superfluous Brackets When Teaching the Rules for the Order of Operations?

    Science.gov (United States)

    Gunnarsson, Robert; Sönnerhed, Wang Wei; Hernell, Bernt

    2016-01-01

    The hypothesis that mathematically superfluous brackets can be useful when teaching the rules for the order of operations is challenged. The idea of the hypothesis is that with brackets it is possible to emphasize the order priority of one operation over another. An experiment was conducted where expressions with mixed operations were studied,…

  1. The discoloring effects of food on the color stability of esthetic brackets - an in-vitro study

    NARCIS (Netherlands)

    Wriedt, Susanne; Schepke, Ulf; Wehrbein, Heiner

    2007-01-01

    Aim: The purpose of this study was to investigate the discoloring effect of certain foods on the color stability of esthetic brackets made of different materials. Material and Methods: Ten specimens of six different tooth-colored brackets were immersed for 10 days at 37 degrees C in various solution

  2. Oral bacterial adhesion forces to biomaterial surfaces constituting the bracket-adhesive-enamel junction in orthodontic treatment

    NARCIS (Netherlands)

    Mei, Li; Busscher, Henk J; van der Mei, Henny C; Chen, Yangxi; de Vries, Joop; Ren, Yijin

    2009-01-01

    Bacterial adhesion to biomaterial surfaces constituting the bracket-adhesive-enamel junction represents a growing problem in orthodontics, because bacteria can adversely affect treatment by causing demineralization of the enamel surface around the brackets. It is important to know the forces with wh

  3. Effect of clearfil protect bond and transbond plus self-etch primer on shear bond strength of orthodontic brackets

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    S Hamid Raji

    2011-01-01

    Conclusion: The shear bond strength of clearfil protect bond and transbond plus self-etch primer was enough for bonding the orthodontic brackets. The mode of failure of bonded brackets with these two self-etch primers is safe for enamel.

  4. Níveis de lisina digestível em rações, utilizando-se o conceito de proteína ideal, para suínos machos castrados de alto potencial genético, dos 30 aos 60 kg Dietary digestible lysine requirements, based on the ideal protein concept, for barrows with high genetic potential from 30 to 60 kg

    Directory of Open Access Journals (Sweden)

    Márvio Lobão Teixeira de Abreu

    2007-02-01

    Full Text Available Objetivou-se determinar o efeito de níveis de lisina digestível, utilizando-se o conceito de proteína ideal, sobre o desempenho e as características de carcaça de 40 leitões machos castrados (peso inicial de 30,02 ± 1,38 kg e peso final 60,44 ± 1,81 kg de alto potencial genético para deposição de carne magra. Os animais foram distribuídos em delineamento de blocos ao acaso, com quatro tratamentos, cinco repetições e dois animais por unidade experimental. Os tratamentos consistiram de uma ração basal (18,08% de PB e 3.250 kcal de EM/kg suplementada com L-lisina HCL, resultando em rações com 0,80; 0,90; 1,00 e 1,10% de lisina digestível. As rações foram suplementadas com níveis crescentes de aminoácidos sintéticos, mantendo-se constantes as relações entre os níveis desses aminoácidos essenciais e os de lisina, com base na digestibilidade verdadeira. Não houve efeito dos tratamentos sobre o consumo de ração, o ganho de peso diário e a concentração de uréia no plasma dos animais. Observou-se comportamento linear da conversão alimentar, que melhorou, e do consumo de lisina digestível diário, que aumentou em função dos níveis de lisina digestível da ração. Os tratamentos não influenciaram as porcentagens de água, proteína e gordura e a deposição de gordura na carcaça dos animais. Os níveis de lisina digestível afetaram de forma linear crescente a deposição de proteína na carcaça. O nível de 1,10% de lisina digestível, correspondente a um consumo de lisina digestível de 21,94 g/dia (3,43 g de Lis/Mcal de EM proporcionou os melhores resultados de desempenho e características de carcaça de suínos machos castrados de alto potencial genético dos 30 aos 60 kg.The effect of increasing dietary digestible lysine levels, based on the ideal protein concept, on performance and carcass characteristics of forty barrows with high genetic potential for lean gain averaging initial and final body weights of

  5. Resistance to Sliding in Clear and Metallic Damon 3 and Conventional Edge-wise Brackets: an In vitro Study

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    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.

  6. Influence of microhybrid resin and etching times on bleached enamel for the bonding of ceramic brackets.

    Science.gov (United States)

    Firoozmand, Leily Macedo; Brandão, Juliana Viana Pereira; Fialho, Melissa Proença Nogueira

    2013-01-01

    The aim of this study was to evaluate the shear bond strength (SBS) of polycrystalline ceramic brackets (PCB) bonded after bleaching treatment using different composite resins and enamel etching times. A total of 144 bovine incisors were randomly divided into two study groups (n = 72, each) as follows: G1, enamel bleached with 35% hydrogen peroxide, and G2 (control group), enamel unbleached. After the bleaching treatment, the samples were stored in artificial saliva for 14 days. These groups were further divided into two subgroups (n = 36, each) as follows: GA, brackets bonded with Transbond XT (3M) and GB, brackets bonded with Filtek Z250 (3M). For each resin used, three different etching times with 37% phosphoric acid (15, 30 and 60 seconds) were tested. SBS tests were performed using a universal testing machine (EMIC), and the adhesive remnant index (ARI) score was verified. Significant differences among the three experimental conditions and interactions between the groups were observed. The type of composite resin accounted for 24% of the influence on the bond strength, whereas the etching time and bleaching treatment accounted for 14.5% and 10% of the influence on bond strength, respectively. The ARI revealed that the most common area of adhesion failure was at the composite resin-bracket interface. The type of composite resin, etching time and external bleaching significantly influenced the SBS of PCB on enamel, even after 14 days of saliva storage.

  7. Transparent magnesium aluminate spinel: a prospective biomaterial for esthetic orthodontic brackets.

    Science.gov (United States)

    Krishnan, Manu; Tiwari, Brijesh; Seema, Saraswathy; Kalra, Namitha; Biswas, Papiya; Rajeswari, Kotikalapudi; Suresh, Madireddy Buchi; Johnson, Roy; Gokhale, Nitin M; Iyer, Satish R; Londhe, Sanjay; Arora, Vimal; Tripathi, Rajendra P

    2014-11-01

    Adult orthodontics is recently gaining popularity due to its importance in esthetics, oral and general health. However, none of the currently available alumina or zirconia based ceramic orthodontic brackets meet the esthetic demands of adult patients. Inherent hexagonal lattice structure and associated birefringence limits the visible light transmission in polycrystalline alumina and make them appear white and non transparent. Hence focus of the present study was to assess the feasibility of using magnesium aluminate (MgAl2O4) spinel; a member of the transparent ceramic family for esthetic orthodontic brackets. Transparent spinel specimens were developed from commercially available white spinel powder through colloidal shaping followed by pressureless sintering and hot isostatic pressing at optimum conditions of temperature and pressure. Samples were characterized for chemical composition, phases, density, hardness, flexural strength, fracture toughness and optical transmission. Biocompatibility was evaluated with in-vitro cell line experiments for cytotoxicity, apoptosis and genotoxicity. Results showed that transparent spinel samples had requisite physico-chemical, mechanical, optical and excellent biocompatibility for fabricating orthodontic brackets. Transparent spinel developed through this method demonstrated its possibility as a prospective biomaterial for developing esthetic orthodontic brackets.

  8. Shear bond strength of self-ligating orthodontic brackets on different types of porcelain crowns

    Directory of Open Access Journals (Sweden)

    Karamdeep Singh Ahluwalia

    2013-01-01

    Full Text Available Aim: The aim of this study is to compare shear bond strength (SBS and adhesive remnant index (ARI of self-ligating orthodontic brackets bonded to different porcelain crowns. Materials and Methods: Three groups of different types of porcelain crowns, each containing 12 crowns were fabricated by the same technician and allocated to one of the study groups as follows: Group I - IPS porcelain crowns (Ivoclar Vivadent AG, Schaan, Liechtenstein, Group II - Porcelain fused to zirconia crowns (Zirkonzahn GmbH, Gais, Italy, Noritake Co., Tokyo, Japan and Group III - Conventional porcelain fused to metal crowns (Ceramco3, Densply, PA, USA. The orthodontic brackets were bonded to these crowns using hydrofluoric acid (HFA + silane etching protocol. After bonding, the SBS of the brackets were tested with a universal testing machine under standard test conditions. Results: Statistical evaluation using analysis of variance showed a significant difference between the groups (P 0.05. Chi-square comparison revealed no significant difference in ARI scores between groups (P > 0.05. Conclusions: When HFA + silane etching protocol were used, IPS crowns showed the greatest SBS of orthodontic brackets. The ARI score was non-significant. Therefore, if there is a need to place crowns over teeth then these crowns can be used for restoration of teeth before orthodontic treatment.

  9. Effect of Enamel Preparation and Light Curing Methods on Microleakage under Orthodontic Brackets

    Directory of Open Access Journals (Sweden)

    Hamidreza Pakshir

    2015-11-01

    Full Text Available Objectives: This study aimed to compare the microleakage beneath metallic brackets following two different methods of enamel preparation and light curing.Materials and Methods: A total of 120 bovine deciduous lower incisors were randomly divided into four groups of 30 teeth. The preparations were as follows: Group I: Acid etching + Transbond XT primer + direct illumination, group II: acid etching + Transbond XT primer + transillumination, group III: Transbond XT self-etching primer + direct illumination and Group IV: Transbond XT self-etching primer + transillumination. Dye penetration was used as the method of microleakage evaluation. Sections made at the enamel-adhesive and adhesive-bracket interfaces were evaluated under a stereomicroscope. The Kruskal-Wallis and Mann-Whitney U tests were used for statistical analysis. The level of significance was set at P<0.05.Results: All groups showed greater microleakage at the gingival in comparison to the incisal margin and the differences were significant among groups with transillumination (P<0.001. No significant differences were observed in the microleakage scores at the gingival and incisal margins in any of the interfaces (P>0.05. Mesiodistal margins of the self-etching group with direct illumination showed significantly lower scores in comparison with acid etched group (P<0.05.Conclusion: Use of self-etching primers for bonding of orthodontic brackets yields acceptable results if all bracket margins are cured directly.

  10. Bonding polycarbonate brackets to ceramic: : Effects of substrate treatment on bond strength

    NARCIS (Netherlands)

    Özcan, Mutlu; Vallittu, Pekka K.; Peltomäki, Timo; Huysmans, Marie-Charlotte; Kalk, Warner

    2004-01-01

    This study evaluated the effects of 5 different surface conditioning methods on the bond strength of polycarbonate brackets bonded to ceramic surfaces with resin based cement. Six disc-shaped ceramic specimens (feldspathic porcelain) with glazed surfaces were used for each group. The specimens were

  11. Bonding polycarbonate brackets to ceramic : Effects of substrate treatment on bond strength

    NARCIS (Netherlands)

    Özcan, Mutlu; Vallittu, Pekka K.; Peltomäki, Timo; Huysmans, Marie-Charlotte; Kalk, Warner

    2004-01-01

    This study evaluated the effects of 5 different surface conditioning methods on the bond strength of polycarbonate brackets bonded to ceramic surfaces with resin based cement. Six disc-shaped ceramic specimens (feldspathic porcelain) with glazed surfaces were used for each group. The specimens were

  12. Effect of alloy type and surface conditioning on roughness and bond strength of metal brackets

    NARCIS (Netherlands)

    Nergiz, I.; Schmage, P.; Herrmann, W.; Ozcan, M.; Nergiz, [No Value

    2004-01-01

    The effect of 5 different surface conditioning methods on bonding of metal brackets to cast dental alloys was examined. The surface conditioning methods were fine (30-µm) or rough (125-µm) diamond bur, sandblasting (50-µm or 110-µm aluminum oxide [Al2O3]), and silica coating (30-µm silica). Fifty di

  13. Effect of toothbrushing with different manual toothbrushes on the shear bond strength of orthodontic brackets

    Directory of Open Access Journals (Sweden)

    Guilherme José Pimentel Lopes de Oliveira

    2010-09-01

    Full Text Available The aim of this study was to evaluate the effect of brushing with a Colgate 360º or Oral B Indicator 35 toothbrush on the shear bond strength of orthodontic brackets bonded to extracted human teeth. The bristle wear and bristle tip morphology were also examined after simulated tooth-brushing. Orthodontic brackets (Roth-P/1st and 2nd premolar S/D- Slot 0.18" were bonded (Transbond XT® to the smoothest surface of each of 45 extracted human molar and premolar teeth. Test specimens were randomly divided into three groups: Group 1, control group with no brushing; Group 2, brushing with the Oral B Indicator 35; Group 3, brushing with the Colgate 360º. Samples were adapted to a machine that simulated tooth-brushing. The bond strength of each bracket to each tooth was assessed with a mechanical testing machine. The bristle wear and bristle tip morphology indices were also assessed. Statistically significant differences were defined for p < 0.05. The average bond strengths (range: 90.18-90.89 kgf/cm² did not differ among the three groups. The Colgate 360º showed less bristle wear and a better bristle tip morphology than the Oral B Indicator 35 toothbrush. However, use of either toothbrush did not decrease the bond strength of the orthodontic brackets. Therefore, patients undergoing orthodontic therapy can safely use either toothbrush.

  14. Difference equations and cluster algebras I: Poisson bracket for integrable difference equations

    CERN Document Server

    Inoue, Rei

    2010-01-01

    We introduce the cluster algebraic formulation of the integrable difference equations, the discrete Lotka-Volterra equation and the discrete Liouville equation, from the view point of the general T-system and Y-system. We also study the Poisson structure for the cluster algebra, and give the associated Poisson bracket for the two difference equations.

  15. Influence of microhybrid resin and etching times on bleached enamel for the bonding of ceramic brackets

    Directory of Open Access Journals (Sweden)

    Leily Macedo Firoozmand

    2013-04-01

    Full Text Available The aim of this study was to evaluate the shear bond strength (SBS of polycrystalline ceramic brackets (PCB bonded after bleaching treatment using different composite resins and enamel etching times. A total of 144 bovine incisors were randomly divided into two study groups (n = 72, each as follows: G1, enamel bleached with 35% hydrogen peroxide, and G2 (control group, enamel unbleached. After the bleaching treatment, the samples were stored in artificial saliva for 14 days. These groups were further divided into two subgroups (n = 36, each as follows: GA, brackets bonded with Transbond XT (3M and GB, brackets bonded with Filtek Z250 (3M. For each resin used, three different etching times with 37% phosphoric acid (15, 30 and 60 seconds were tested. SBS tests were performed using a universal testing machine (EMIC, and the adhesive remnant index (ARI score was verified. Significant differences among the three experimental conditions and interactions between the groups were observed. The type of composite resin accounted for 24% of the influence on the bond strength, whereas the etching time and bleaching treatment accounted for 14.5% and 10% of the influence on bond strength, respectively. The ARI revealed that the most common area of adhesion failure was at the composite resin-bracket interface. The type of composite resin, etching time and external bleaching significantly influenced the SBS of PCB on enamel, even after 14 days of saliva storage.

  16. A Mathematica program for the calculation of five-body Moshinsky brackets

    Science.gov (United States)

    Xiao, Shuyuan; Mu, Xueli; Liu, Tingting; Chen, Hong

    2016-06-01

    Five-body Moshinsky brackets that relate harmonic oscillator wavefunctions in two different sets of Jacobi coordinates make it straightforward to calculate some matrix elements in the variational calculations of five-body systems. The analytical expression of these transformation coefficients and the computer code written in the Mathematica language are presented here for accurate calculations.

  17. Evaluation of shear bond strength of orthodontic brackets bonded on the tooth surface after internal bleaching

    Directory of Open Access Journals (Sweden)

    Nadia de Souza FERREIRA

    Full Text Available Introduction: There is great demand for esthetic treatment by patients who have discolored teeth, because currently aesthetic standards have become stricter and many patients have tooth bleaching procedures performed before or during orthodontic treatment. Objective: To evaluate the bonding of orthodontic brackets to human molars after internal tooth bleaching. Material and method: Forty molars were divided into four groups according to the bleaching agent used: PS sodium perborate + water; PC carbamide peroxide; PC + PS carbamide peroxide + sodium perborate; Cont water (control group. Bleaching agents placed inside the pulp chambers were replaced every 7 days for 2 weeks, and the brackets were bonded 30 days after the end of bleaching. The shear strength test was performed in a universal testing machine (Emic. Result: ANOVA with a significance level of 5% (p > 0.05, showed no statistically significant difference between groups (p = 0.1214. Conclusion: It was concluded that the different bleaching agents studied did not interfere with the bond strength of brackets to enamel and bonding the brackets 30 days after internal bleaching is a safe procedure.

  18. Dirichlet-Neumann bracketing for boundary-value problems on graphs

    Directory of Open Access Journals (Sweden)

    Sonja Currie

    2005-08-01

    Full Text Available We consider the spectral structure of second order boundary-value problems on graphs. A variational formulation for boundary-value problems on graphs is given. As a consequence we can formulate an analogue of Dirichlet-Neumann bracketing for boundary-value problems on graphs. This in turn gives rise to eigenvalue and eigenfunction asymptotic approximations.

  19. Actual versus theoretical torsional play in conventional and self-ligating bracket systems

    DEFF Research Database (Denmark)

    Dalstra, Michel; Eriksen, Henrik; Bergamini, Chiara;

    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 resu...

  20. Quantification of white spot lesions around orthodontic brackets with image analysis.

    NARCIS (Netherlands)

    Livas, C.; Kuijpers-Jagtman, A.M.; Bronkhorst, E.; Derks, A.; Katsaros, C.

    2008-01-01

    OBJECTIVE: To investigate the use of image analysis for diagnosis and quantification of artificial white spot lesions on digital photographs before and after removal of orthodontic brackets. MATERIALS AND METHODS: Enamel demineralization was artificially induced on the labial surface of 20 teeth bon

  1. Shear Bond Strength of Ceramic Brackets with Different Base Designs: Comparative In-vitro Study

    Science.gov (United States)

    Ansari, Mohd. Younus; Agarwal, Deepak K; Bhattacharya, Preeti; Ansar, Juhi; Bhandari, Ravi

    2016-01-01

    Introduction Knowledge about the Shear Bond Strength (SBS) of ceramic brackets with different base design is essential as it affects bond strength to enamel. Aim The aim of the present study was to evaluate and compare the effect of base designs of different ceramic brackets on SBS, and to determine the fracture site after debonding. Materials and Methods Four groups of ceramic brackets and one group of metal brackets with different base designs were used. Adhesive precoated base of Clarity Advanced (APC Flash-free) (Unitek/3M, Monrovia, California), microcrystalline base of Clarity Advanced (Unitek/3M, Monrovia, California), polymer mesh base of InVu (TP Orthodontics, Inc., La Porte, IN, United States), patented bead ball base of Inspire Ice (Ormco, Glendora, California), and a mechanical mesh base of Gemini Metal bracket (Unitek/3M, Monrovia, California). Ten brackets of each type were bonded to 50 maxillary premolars with Transbond XT (Unitek/3M). Samples were stored in distilled water at room temperature for 24 hours and subsequently tested in shear mode on a universal testing machine (Model 3382; Instron Corp., Canton, Massachusetts, USA) at a cross head speed of 1mm/minute with the help of a chisel. The debonded interface was recorded and analyzed to determine the predominant bond failure site under an optical microscope (Stereomicroscope) at 10X magnification. One way analysis of variance (ANOVA) was used to compare SBS. Tukey’s significant differences tests were used for post-hoc comparisons. The Adhesive Remnant Index (ARI) scores were compared by chi-square test. Results Mean SBS of microcrystalline base (27.26±1.73), was the highest followed by bead ball base (23.45±5.09), adhesive precoated base (20.13±5.20), polymer mesh base (17.54±1.91), and mechanical mesh base (17.50±2.41) the least. Comparing the frequency (%) of ARI Score among the groups, chi-square test showed significantly different ARI scores among the groups (χ2 = 34.07, p<0

  2. Evaluation of enamel damages following orthodontic bracket debonding in fluorosed teeth bonded with adhesion promoter

    Science.gov (United States)

    Baherimoghadam, Tahreh; Akbarian, Sahar; Rasouli, Reza; Naseri, Navid

    2016-01-01

    Objective: To evaluate shear bond strength (SBS) of the orthodontic brackets bonded to fluorosed and nonfluorosed teeth using Light Bond with and without adhesion promoters and compare their enamel damages following debonding. Materials and Methods: In this study, 30 fluorosed (Thylstrup and Fejerskov Index = 4–5) and 30 nonfluorosed teeth were randomly distributed between two subgroups according to the bonding materials: Group 1, fluorosed teeth bonded with Light Bond; Group 2, fluorosed teeth bonded with adhesion promoters and Light Bond; Group 3, nonfluorosed teeth bonded with Light Bond; Group 4, nonfluorosed bonded with adhesion promoters and Light Bond. After bonding, the SBS of the brackets was tested with a universal testing machine. Stereomicroscopic evaluation was performed by unbiased stereology in all teeth to determine the amount of adhesive remnants and the number and length of enamel cracks before bonding and after debonding. The data were analyzed using two-way analysis of variance, Kruskal–Wallis, Wilcoxon Signed Rank, and Mann–Whitney test. Results: While fluorosis reduced the SBS of orthodontic bracket (P = 0.017), Enhance Locus Ceruleus LC significantly increased the SBS of the orthodontic bracket in fluorosed and nonfluorosed teeth (P = 0.039). Significant increasing in the number and length of enamel crack after debonding was found in all four groups. There were no significant differences in the length of enamel crack increased after debonding among four groups (P = 0.768) while increasing in the number of enamel cracks after debonding was significantly different among the four groups (P = 0.023). Teeth in Group 2 showed the highest enamel damages among four groups following debonding. Conclusion: Adhesion promoters could improve the bond strength of orthodontic brackets, but conservative debonding methods for decreasing enamel damages would be necessary. PMID:27095895

  3. Effect of Four Methods of Surface Treatment on Shear Bond Strength of Orthodontic Brackets to Zirconium

    Directory of Open Access Journals (Sweden)

    Soghra Yassaei

    2015-10-01

    Full Text Available Objectives: Providing reliable attachment between bracket base and zirconia surface is a prerequisite for exertion of orthodontic force. The purpose of the present study was to eval- uate the effect of four zirconium surface treatment methods on shear bond strength (SBS of orthodontic brackets.Materials and Methods: One block of zirconium was trimmed into four zirconium sur- faces, which served as our four study groups and each had 18 metal brackets bonded to them. Once the glazed layer was removed, the first group was etched with 9.6% hydrofluoric acid (HF, and the other three groups were prepared by means of sandblasting and 1 W, and 2 W Er: YAG laser, respectively. After application of silane, central incisor brackets were bonded to the zirconium surfaces. The SBS values were measured by a Dartec testing ma- chine with a crosshead speed of 1 mm/min.Results: The highest SBS was achieved in the sandblasted group (7.81±1.02 MPa followed in a descending order by 2 W laser group (6.95±0.87 MPa, 1 W laser group (6.87±0.92MPa and HF acid etched group (5.84±0.78 MPa. The differences between the study groups, were statistically significant except between the laser groups (P < 0.05. Conclusion: In terms of higher bond strength and safety, sandblasting and Er: YAG laser irradiation with power output of 1 W and 2 W can be considered more appropriate alterna- tives to HF acid etching for zirconium surface treatment prior to bracket bonding.

  4. Evaluation of the force generated by gradual deflection of orthodontic wires in conventional metallic, esthetic, and self-ligating brackets

    Directory of Open Access Journals (Sweden)

    Manoela Fávaro Francisconi

    Full Text Available ABSTRACT Objective: The purpose of this study was to evaluate the deflection forces of Nitinol orthodontic wires placed in different types of brackets: metallic, reinforced polycarbonate with metallic slots, sapphire, passive and active self-ligating, by assessing strength values variation according to gradual increase in wire diameter and deflection and comparing different combinations in the different deflections. Material and Methods: Specimens were set in a clinical simulation model and evaluated in a Universal Testing Machine (INSTRON 3342, using the ISO 15841 protocol. Data were subjected to One-way ANOVA, followed by Tukey tests (p<0.05. Results: Self-ligating brackets presented the most similar behavior to each other. For conventional brackets there was no consistent behavior for any of the deflections studied. Conclusions: Self-ligating brackets presented the most consistent and predictable results while conventional brackets, as esthetic brackets, showed very different patterns of forces. Self-ligating brackets showed higher strength in all deflections when compared with the others, in 0.020-inch wires.

  5. PERBANDINGAN TEKNIS DAN EKONOMIS ANTARA PENGGANTIAN BANTALAN POROS PROPELLER DIBANDINGKAN DENGAN PENGGESERAN POSISI V-BRACKET PADA KMP. KUMALA

    Directory of Open Access Journals (Sweden)

    Untung Budiarto

    2012-02-01

    Full Text Available In the propulsion systems there are three preference components main engine, propeller shaft, and propeller.KMP. Kumala is one for all passengers ship the owner PT. Darma Lautan Utama, there are it’s to experienceproblems to the systems propulsion to happen missalignment between construction v-bracket with sterntube,there are v-bracket to function become to hold up propeller shaft in the inside to find shaft bearing. Effect themissalignment, shaft can’t to turn, so need the realized preparing with the change to shaft bearing shapeexentric and to scrape position v-bracket the position again. In this finish task purporting to know the valuefrom side technics and economics between to realized the change shaft bearing shape exentric with to scrapeposition v-bracket to position again with account time to docking next time. From the result analyse to find thatto change the shaft bearing shape exentric to need faster time, material cost is more expensive, labour cost ischeaper, construction to v-bracket isn’t normaly, than to scrape position v-bracket to need the time is long time,material cost is cheaper, job cost is more expensive, construction v-bracket back to normal the position again,until to moment realization docking next time to need faster time, material cost and job cost is cheaper from tochange the shaft bearing shape exentric.

  6. Evaluation of stiffness and plastic deformation of active ceramic self-ligating bracket clips after repetitive opening and closure movements

    Directory of Open Access Journals (Sweden)

    Grace Kelly Martins Carneiro

    2015-08-01

    Full Text Available OBJECTIVE: The aim of this study was to assess whether repetitive opening and closure of self-ligating bracket clips can cause plastic deformation of the clip.METHODS: Three types of active/interactive ceramic self-ligating brackets (n = 20 were tested: In-Ovation C, Quicklear and WOW. A standardized controlled device performed 500 cycles of opening and closure movements of the bracket clip with proper instruments and techniques adapted as recommended by the manufacturer of each bracket type. Two tensile tests, one before and one after the repetitive cycles, were performed to assess the stiffness of the clips. To this end, a custom-made stainless steel 0.40 x 0.40 mm wire was inserted into the bracket slot and adapted to the universal testing machine (EMIC DL2000, after which measurements were recorded. On the loading portion of the loading-unloading curve of clips, the slope fitted a first-degree equation curve to determine the stiffness/deflection rate of the clip.RESULTS: The results of plastic deformation showed no significant difference among bracket types before and after the 500 cycles of opening and closure (p = 0.811. There were significant differences on stiffness among the three types of brackets (p = 0.005. The WOW bracket had higher mean values, whereas Quicklear bracket had lower values, regardless of the opening/closure cycle.CONCLUSION: Repetitive controlled opening and closure movements of the clip did not alter stiffness or cause plastic deformation.

  7. Comparison of Antibacterial Effects of ZnO and CuO Nanoparticles Coated Brackets against Streptococcus Mutans

    Directory of Open Access Journals (Sweden)

    Baratali Ramazanzadeh

    2015-09-01

    Full Text Available Statement of the Problem: During the orthodontic treatment, microbial plaques may accumulate around the brackets and cause caries, especially in high-risk patients. Finding ways to eliminate this microbial plaque seems to be essential. Purpose: The aim of this study was to compare the antibacterial effects of nano copper oxide (CuO and nano zinc oxide (ZnO coated brackets against Streptococcus mutans (S.mutans in order to decrease the risk of caries around the orthodontic brackets during the treatment. Materials and Method: Sixty brackets were coated with nanoparticles of ZnO (n=20, CuO (n=20 and CuO-ZnO (n=20. Twelve uncoated brackets constituted the control group. The brackets were bonded to the crowns of extracted premolars, sterilized and prepared for antimicrobial tests (S.mutans ATCC35668. The samples taken after 0, 2, 4, 6 and 24 hours were cultured on agar plates. Colonies were counted 24 hours after incubation. One-way ANOVA and Tukey tests were used for statistical analysis. Results: In CuO and CuO-ZnO coated brackets, no colony growth was seen after two hours. Between 0-6 hours, the mean colony counts were not significantly different between the ZnO and the control group (p>0.05. During 6-24 hours, the growth of S.mutans was significantly reduced by ZnO nanoparticles in comparison with the control group (p< 0.001. However, these bacteria were not totally eliminated. Conclusion: CuO and ZnO-CuO nanoparticles coated brackets have better antimicrobial effect on S.mutans than ZnO coated brackets.

  8. Anterior Sectional Twin Bracket Appliance - Innovative Use for Correction of Single Tooth Crossbite: A Case Report with Biomechanics.

    Science.gov (United States)

    Verma, Raj Kumar; Raghav, Pradeep; Reddy, Munish C; Kanwal, Ritika

    2015-01-01

    Anterior sectional twin bracket appliance (ASTBA) is a sectional mechanism that involves two brackets on upper central incisors. This appliance is previously been used for correction of rotated incisors and midline spacing. But, detail biomechanics for single tooth crossbite correction is not previously explained. Here, in this article, we are presenting a detailed biomechanics of ASTBA for anterior single tooth crossbite correction along with case report. How to cite this article: Verma RK, Raghav P, Reddy MC, Kanwal R. Anterior Sectional Twin Bracket Appliance- Innovative Use for Correction of Single Tooth Crossbite: A Case Report with Biomechanics. Int J Clin Pediatr Dent 2015;8(1): 66-69.

  9. Deproteinization of tooth enamel surfaces to prevent white spot lesions and bracket bond failure: A revolution in orthodontic bonding

    Directory of Open Access Journals (Sweden)

    Roberto Justus

    2016-01-01

    Full Text Available Orthodontic treatment success is jeopardized by the risk of development of white spot lesions (WSLs around orthodontic brackets. Unfortunately, the formation of WSLs still remains a common complication during treatment in patients with poor oral hygiene. Nearly 75% of orthodontic patients are reported to develop enamel decalcification because of prolonged plaque retention around brackets. It is the orthodontist′s responsibility to minimize the risk of patients having enamel decalcifications as a consequence of orthodontic treatment. This can be achieved by using hybrid, fluoride-releasing, glass ionomer cement to bond brackets, with deproteinization of the enamel surface before phosphoric acid etching.

  10. Are Bonding Agents being Effective on the Shear Bond Strength of Orthodontic Brackets Bonded to the Composite?

    Directory of Open Access Journals (Sweden)

    Fahimeh Farzanegan

    2014-06-01

    Full Text Available Introduction: One of the clinical problems in orthodontics is the bonding of brackets tocomposite restorations. The aim of this study was to evaluate the shear bondstrength of brackets bonded to composite restorations using Excite. Methods:Forty brackets were bonded to composite surfaces, which were embedded inacrylic resin. One of the following four protocols was employed for surfacepreparation of the composite: group 1 37% phosphoric acid for 60 seconds, group2 roughening with a diamond bur plus 37% phosphoric acid for 60 seconds, group3 37% phosphoric acid for 60 seconds and the applying Excite®, group4 roughening with diamond bur plus 37% phosphoric acid for 60 seconds andapplying Excite®. Maxillary central brackets were bonded onto thecomposite prepared samples with Transbond XT. Shear Bond Strength (SBS wasmeasured by a universal testing machine. The ANOVA and Tukey test was utilizedfor data analysis. Results: There was a significant difference betweenthe four groups (P

  11. Reduction in static friction by deposition of a homogeneous diamond-like carbon (DLC) coating on orthodontic brackets.

    Science.gov (United States)

    Akaike, Shun; Hayakawa, Tohru; Kobayashi, Daishiro; Aono, Yuko; Hirata, Atsushi; Hiratsuka, Masanori; Nakamura, Yoshiki

    2015-01-01

    In orthodontics, a reduction in static friction between the brackets and wire is important to enable easy tooth movement. The aim of this study was to examine the effects of a homogeneous diamond-like carbon (DLC) coating on the whole surfaces of slots in stainless steel orthodontic brackets on reducing the static friction between the brackets and the wire. The DLC coating was characterized using Raman spectroscopy, surface roughness and contact angle measurements, and SEM observations. Rectangular stainless steel and titanium-molybdenum alloy wires with two different sizes were employed, and the static friction between the brackets and wire was measured under dry and wet conditions. The DLC coating had a thickness of approximately 1.0 μm and an amorphous structure was identified. The results indicated that the DLC coating always led to a reduction in static friction.

  12. Influence of adhesion promoters and curing-light sources on the shear bond strength of orthodontic brackets

    Directory of Open Access Journals (Sweden)

    Claudia Tavares Machado

    2012-01-01

    Conclusions: The conventional orthodontic adhesive presented higher bond strength than the nanofilled composite, although both materials interacted similarly to the teeth. The curing-light devices tested did not influence on bond strength of orthodontic brackets.

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

    Institute of Scientific and Technical Information of China (English)

    LI Fujun; PENG Youjian; PENG Bin

    2009-01-01

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

  14. Poisson Bracket for Fermion Fields: Correspondence Principle, Second Class Constraints and Hamilton-Jacobi equation

    CERN Document Server

    Leclerc, M

    2012-01-01

    We introduce a symmetric Poisson bracket that allows us to describe anticommuting fields on a classical level in the same way as commuting fields, without the use of Grassmann variables. By means of a simple example, we show how the Dirac bracket for the elimination of the second class constraints can be introduced, how the classical Hamiltonian equations can be derived and how quantization can be achieved through a direct correspondence principle. Finally, we show that the semiclassical limit of the corresponding Schroedinger equation leads back to the Hamilton-Jacobi equation of the classical theory. Summarizing, it is shown that the relations between classical and quantum theory are valid for fermionic fields in exactly the same way as in the bosonic case, and that there is no need to introduce anticommuting variables on a classical level.

  15. Altered Passive Eruption Complicating Optimal Orthodontic Bracket Placement: A Case Report and Review of Literature

    Science.gov (United States)

    Chitra, Prasad

    2015-01-01

    An unusual case of altered passive eruption with gingival hyperpigmentation and a Class I malocclusion in a 12-year-old girl having no previous history of medication is presented. The patient reported with spacing in the upper arch, moderate crowding in the lower arch, anterior crossbite and excessive gingival tissue on the labial surfaces of teeth in both the arches. The inadequate crown lengths made placement of the orthodontic brackets difficult. Preadjusted orthodontic brackets have a very precise placement protocol which can affect tooth movement in all 3 planes of space if violated. The periodontal condition was diagnosed as altered passive eruption Type IA. Interdisciplinary treatment protocols including periodontal surgical and orthodontic procedures were used. The periodontal surgical procedures were carried out prior to orthodontic therapy and the results obtained were satisfactory. It is suggested that orthodontists should be aware of conditions like altered passive eruption and modalities of management. In most instances, orthodontic therapy is not hindered. PMID:26672498

  16. HOTB: High precision parallel code for calculation of four-particle harmonic oscillator transformation brackets

    Science.gov (United States)

    Stepšys, A.; Mickevicius, S.; Germanas, D.; Kalinauskas, R. K.

    2014-11-01

    This new version of the HOTB program for calculation of the three and four particle harmonic oscillator transformation brackets provides some enhancements and corrections to the earlier version (Germanas et al., 2010) [1]. In particular, new version allows calculations of harmonic oscillator transformation brackets be performed in parallel using MPI parallel communication standard. Moreover, higher precision of intermediate calculations using GNU Quadruple Precision and arbitrary precision library FMLib [2] is done. A package of Fortran code is presented. Calculation time of large matrices can be significantly reduced using effective parallel code. Use of Higher Precision methods in intermediate calculations increases the stability of algorithms and extends the validity of used algorithms for larger input values. Catalogue identifier: AEFQ_v4_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEFQ_v4_0.html Program obtainable from: CPC Program Library, Queen’s University of Belfast, N. Ireland Licensing provisions: GNU General Public License, version 3 Number of lines in programs, including test data, etc.: 1711 Number of bytes in distributed programs, including test data, etc.: 11667 Distribution format: tar.gz Program language used: FORTRAN 90 with MPI extensions for parallelism Computer: Any computer with FORTRAN 90 compiler Operating system: Windows, Linux, FreeBSD, True64 Unix Has the code been vectorized of parallelized?: Yes, parallelism using MPI extensions. Number of CPUs used: up to 999 RAM(per CPU core): Depending on allocated binomial and trinomial matrices and use of precision; at least 500 MB Catalogue identifier of previous version: AEFQ_v1_0 Journal reference of previous version: Comput. Phys. Comm. 181, Issue 2, (2010) 420-425 Does the new version supersede the previous version? Yes Nature of problem: Calculation of matrices of three-particle harmonic oscillator brackets (3HOB) and four-particle harmonic oscillator brackets (4HOB) in a more

  17. Simulation and experimental validation of powertrain mounting bracket design obtained from multi-objective topology optimization

    OpenAIRE

    Qinghai Zhao; Xiaokai Chen; Lu Wang; Jianfeng Zhu; Zheng-Dong Ma; Yi Lin

    2015-01-01

    A framework of multi-objective topology optimization for vehicle powertrain mounting bracket design with consideration of multiple static and dynamic loading conditions is developed in this article. Incorporating into the simplified isotropic material with penalization model, compromise programming method is employed to describe the multi-objective and multi-stiffness topology optimization under static loading conditions, whereas mean eigenvalue formulation is proposed to analyze vibration op...

  18. Comparison of various products for the prevention of demineralization in the bracket environment

    OpenAIRE

    Coordes, Stefanie Louise

    2013-01-01

    Sealers and varnishes are used for the prophylaxis of demineralization in patients with multi-bracket treatment. Several agents have been recently introduced for this purpose. However, it remains unclear which one is more efficient and could be suggested as standard of care in this patient cohort. The aim of this study was to compare the long-term resistance of six different products against thermomechanical and chemical stress in vitro. The agents included in the study were the three fluorid...

  19. Enamel Surface Roughness after Debonding of Orthodontic Brackets and Various Clean-Up Techniques

    OpenAIRE

    2013-01-01

    Objective: This study aimed to evaluate enamel roughness after adhesive removal using different burs and an Er:YAG laser. Materials and Methods: The buccal surfaces of forty human premolars were sealed by two layers of nail varnish, except for a circular area of 3 mm in diameter on the middle third. The enamel surfaces were initially subjected to profilometry analysis and four parameters of surface irregularity (Ra, Rq, Rt and Rz) were recorded. Following bracket bonding and debonding, adhesi...

  20. Are self-ligating brackets related to less formation of Streptococcus mutans colonies? A systematic review

    Directory of Open Access Journals (Sweden)

    Leonard Euler Andrade Gomes do Nascimento

    2014-01-01

    Full Text Available OBJECTIVE: To verify, by means of a systematic review, whether the design of brackets (conventional or self-ligating influences adhesion and formation of Streptococcus mutans colonies. METHODS: Search strategy: four databases (Cochrane Central Register of Controlled Trials, Ovid ALL EMB Reviews, PubMed and BIREME were selected to search relevant articles covering the period from January 1965 to December 2012. Selection Criteria: in first consensus by reading the title and abstract. The full text was obtained from publications that met the inclusion criteria. Data collection and analysis: Two reviewers independently extracted data using the keywords: conventional, self-ligating, biofilm, Streptococcus mutans, and systematic review; and independently evaluated the quality of the studies. In case of divergence, the technique of consensus was adopted. RESULTS: The search strategy resulted in 1,401 articles. The classification of scientific relevance revealed the high quality of the 6 eligible articles of which outcomes were not unanimous in reporting not only the influence of the design of the brackets (conventional or self-ligating over adhesion and formation of colonies of Streptococcus mutans, but also that other factors such as the quality of the bracket type, the level of individual oral hygiene, bonding and age may have greater influence. Statistical analysis was not feasible because of the heterogeneous methodological design. CONCLUSIONS: Within the limitations of this study, it was concluded that there is no evidence for a possible influence of the design of the brackets (conventional or self-ligating over colony formation and adhesion of Streptococcus mutans.

  1. Truncated Nambu-Poisson Bracket and Entropy Formula for Multiple Membranes

    CERN Document Server

    Chu, Chong-Sun; Matsuo, Yutaka; Shiba, Shotaro

    2008-01-01

    We show that there exists a cut-off version of Nambu-Poisson bracket which defines a finite dimensional Lie 3-algebra. The algebra still satisfies the fundamental identity and thus produces N=8 supersymmetric BLG type equation of motion for multiple M2 branes. By counting the number of the moduli and the degree of freedom, we derive an entropy formula which scales as N^{3/2} as expected for the multiple M2 branes.

  2. Transversal changes in dental arches from non-extraction treatment with self ligating brackets

    OpenAIRE

    Liliana Avila Maltagliati; Yasushi Inoue Myiahira; Liana Fattori; Leopoldino Capelozza Filho; Mauricio Cardoso

    2013-01-01

    OBJECTIVE: The present study aimed at analyzing, with the use of dental casts, the transverse changes of the upper and lower dental arches, after non-extraction orthodontic treatment, with self-ligating brackets. METHODS: The sample comprised 29 patients, all presenting Class I malocclusion with upper and lower crowding of at least 4 mm and treated only with a fixed appliance, without stripping, extraction or distalization. The dental casts were obtained before and after leveling with 0.019 x...

  3. Fluoride-Releasing Materials to Prevent White Spot Lesions around Orthodontic Brackets: A Systematic Review

    OpenAIRE

    Nascimento,Patrícia Layane de Menezes Macêdo; Fernandes,Micaelle Tenório Guedes; de Figueiredo, Fabricio Eneas Diniz; Faria-e-Silva,André Luis

    2016-01-01

    Abstract The relation between orthodontic fixed appliances use and enamel demineralization is well established. Different preventive approaches have been suggested to this problem, but controversy remains about which is the best. The aim of this study was to perform a systematic review of clinical trials that investigated the effectiveness of materials containing fluorides to lute brackets or cover the bonding interface in order to inhibit the development and progression of white spot lesions...

  4. Effect of dental bleaching after bracket bonding and debonding using three different adhesive systems

    Directory of Open Access Journals (Sweden)

    Lucianna de Oliveira Gomes

    2013-04-01

    Full Text Available OBJECTIVE: To evaluate the influence of bonding and debonding of orthodontic brackets on dental in-home bleaching, taking into account three different adhesive systems. METHODS: Forty-four bovine incisors were divided into four groups according to the primer system used for orthodontic bracket bonding. Following the debonding of orthodontic brackets, the teeth were stored in staining solution for 96 hours. Then, teeth were whitened using 10% carbamide peroxide for two weeks at a 6-hour-a-day regime. Standardized digital photographs were taken at the following intervals: T0 (initial; T1 (after debonding; T2 (after pigmentation; T3, T4 and T5 representing 1, 7, and 14 days of bleaching. Repeatability and stability tests were carried out to check the method accuracy. Images were analyzed using Adobe Photoshop 7.0 software considering (L*a*b*color coordinate values and a modified color difference total (Δ;E'. RESULTS: The results of this study (ANOVA and Tukey; p < 0.01 demonstrated that after 7 days of bleaching, experimental groups showed significantly less teeth whitening compared to the control group. However, there were no significant color differences between the groups after 14 days, according to values of lightness (L*. CONCLUSIONS: Regardless of the adhesive primer system applied, bonding and debonding of orthodontic brackets alters the outcome of tooth whitening in the first 7 days of bleaching, however it has no influence on the whitening of the dental structure after 14 days of in-home dental bleaching with 10% carbamide peroxide.

  5. Effects of silica coating and silane surface conditioning on the bond strength of rebonded metal and ceramic brackets

    Directory of Open Access Journals (Sweden)

    Saadet Atsü

    2011-06-01

    Full Text Available OBJECTIVE: The aim of this study was to evaluate the effects of tribochemical silica coating and silane surface conditioning on the bond strength of rebonded metal and ceramic brackets. MATERIAL AND METHODS: Twenty debonded metal and 20 debonded ceramic brackets were randomly assigned to receive one of the following surface treatments (n=10 for each group: (1 sandblasting (control; (2 tribochemical silica coating combined with silane. Brackets were rebonded to the enamel surface on the labial and lingual sides of premolars with a light-polymerized resin composite. All specimens were stored in distilled water for 1 week and then thermocycled (5,000 cycles between 5-55ºC. Shear bond strength values were measured using a universal testing machine. Student's t-test was used to compare the data (α=0.05. Failure mode was assessed using a stereomicroscope, and the treated and non-treated bracket surfaces were observed by scanning electron microscopy. RESULTS: Rebonded ceramic brackets treated with silica coating followed by silanization had significantly greater bond strength values (17.7±4.4 MPa than the sandblasting group (2.4±0.8 MPa, P<0.001. No significant difference was observed between the rebonded metal brackets treated with silica coating with silanization (15±3.9 MPa and the sandblasted brackets (13.6±3.9 MPa. Treated rebonded ceramic specimens primarily exhibited cohesive failure in resin and adhesive failure at the enamel-adhesive interface. CONCLUSIONS: In comparison to sandblasting, silica coating with aluminum trioxide particles followed by silanization resulted in higher bond strengths of rebonded ceramic brackets.

  6. Deproteinization of tooth enamel surfaces to prevent white spot lesions and bracket bond failure: A revolution in orthodontic bonding

    OpenAIRE

    Roberto Justus

    2016-01-01

    Orthodontic treatment success is jeopardized by the risk of development of white spot lesions (WSLs) around orthodontic brackets. Unfortunately, the formation of WSLs still remains a common complication during treatment in patients with poor oral hygiene. Nearly 75% of orthodontic patients are reported to develop enamel decalcification because of prolonged plaque retention around brackets. It is the orthodontist′s responsibility to minimize the risk of patients having enamel decalcifications ...

  7. Microhardness of enamel adjacent to orthodontic brackets after CO2 laser irradiation and fluoride application.

    Science.gov (United States)

    Stangler, Leonardo Pucci; Romano, Fábio Lourenço; Shirozaki, Mariana Umekita; Galo, Rodrigo; Afonso, Alessandra Marques Correa; Borsatto, Maria Cristina; Matsumoto, Mírian Aiko Nakane

    2013-01-01

    This study evaluated the effectiveness of carbon dioxide (CO2) laser combined or not with fluoride application on the surface microhardness of enamel adjacent to orthodontic brackets. Fifteen human molars were selected from which 30 enamel fragments measuring 4 mm2 were obtained. The fragments were embedded in PCV tubes with acrylic resin and prepared using water abrasive paper, felt disks and alumina. Orthodontic brackets cut in half were bonded to enamel and 3 microhardness readings were performed on the adjacent surface, as follows: initial, after cariogenic challenge and final. The specimens were divided into the following 3 groups (n=10): Group C: control, Group L: irradiated with CO2 laser, and Group FL: topical fluoride application and CO2 laser irradiation. After initial reading, the specimens were placed in a demineralizing solution for 32 h and the second reading was to verify if demineralization was uniform in all groups. After the treatments, the specimens were submitted to DES-RE cycling for 8 days followed by final surface microhardness reading. The data were analyzed statistically using ANOVA and Duncan test (α=0.05). At the final measurement Group FL obtained higher microhardness value than Groups C and L (pCO2 laser around orthodontic brackets combined or not with topical fluoride application was effective to increase the surface microhardness of enamel.

  8. Preparation and antimicrobial assay of ceramic brackets coated with TiO2 thin films

    Science.gov (United States)

    Cao, Shuai; Wang, Ye; Cao, Lin; Wang, Yu; Lin, Bingpeng; Lan, Wei

    2016-01-01

    Objective Different methods have been utilized to prevent enamel demineralization and other complications during orthodontic treatment. However, none of these methods can offer long-lasting and effective prevention of orthodontic complications or interventions after complications occur. Considering the photocatalytic effect of TiO2 on organic compounds, we hoped to synthesize a novel bracket with a TiO2 thin film to develop a photocatalytic antimicrobial effect. Methods The sol-gel dip coating method was used to prepare TiO2 thin films on ceramic bracket surfaces. Twenty groups of samples were composed according to the experimental parameters. Crystalline structure and surface morphology were characterized by X-ray diffraction and scanning electron microscopy, respectively; film thickness was examined with a surface ellipsometer. The photocatalytic properties under ultraviolet (UV) light irradiation were analyzed by evaluating the degradation ratio of methylene blue (MB) at a certain time. Antibacterial activities of selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. Results Films with 5 coating layers annealed at 700℃ showed the greatest photocatalytic activity in terms of MB decomposition under UV light irradiation. TiO2 thin films with 5 coating layers annealed at 700℃ exhibited the greatest antimicrobial activity under UV-A light irradiation. Conclusions These results provide promising guidance in prevention of demineralization by increasing antimicrobial activities of film coated brackets. PMID:27226960

  9. Bonding brackets on white spot lesions pretreated by means of two methods

    Science.gov (United States)

    Vianna, Julia Sotero; Marquezan, Mariana; Lau, Thiago Chon Leon; Sant'Anna, Eduardo Franzotti

    2016-01-01

    Abstract Objective: The aim of this study was to evaluate the shear bond strength (SBS) of brackets bonded to demineralized enamel pretreated with low viscosity Icon Infiltrant resin (DMG) and glass ionomer cement (Clinpro XT Varnish, 3M Unitek) with and without aging. Methods: A total of 75 bovine enamel specimens were allocated into five groups (n = 15). Group 1 was the control group in which the enamel surface was not demineralized. In the other four groups, the surfaces were submitted to cariogenic challenge and white spot lesions were treated. Groups 2 and 3 were treated with Icon Infiltrant resin; Groups 4 and 5, with Clinpro XT Varnish. After treatment, Groups 3 and 5 were artificially aged. Brackets were bonded with Transbond XT adhesive system and SBS was evaluated by means of a universal testing machine. Statistical analysis was performed by one-way analysis of variance followed by Tukey post-hoc test. Results: All groups tested presented shear bond strengths similar to or higher than the control group. Specimens of Group 4 had significantly higher shear bond strength values (p < 0.05) than the others. Conclusion: Pretreatment of white spot lesions, with or without aging, did not decrease the SBS of brackets. PMID:27275613

  10. Influence of ceramic surface treatment on shear bond strength of ceramic brackets

    Directory of Open Access Journals (Sweden)

    Tatiana Fernandes Ramos

    2012-01-01

    Full Text Available Objective: To compare four different surface treatment methods and determine which produces adequate bond strength between ceramic brackets and facets of porcelain (feldspathic, and evaluate the Adhesive Remnant Index (ARI scores. Materials and Methods: Ten facets of porcelain specimens with glazed surfaces were used for each group. The specimens were randomly assigned to one of the following treatment conditions of the porcelain surface: (1 no surface treatment (control group, (2 fine diamond bur + orthophosphoric acid gel 37%, (3 hydrofluoric acid (HFL 10%, and (4 HFL 10% + silane. Ceramic brackets were bonded with the adhesive cement Transbond XT. The shear bond strength values were measured on a universal testing machine at a crosshead speed of 0.5 mm/min. Results: There was a significant difference (P<0.05 between the control group and all other groups. There was no significant difference (P<0.05 between treated porcelain surface with diamond bur + orthophosphoric acid gel 37% (4.8 MPa and HFL 10% (6.1 MPa, but the group treated with HFL 10% had clinically acceptable bond strength values. The group treated with HFL 10% + silane (17.5 MPa resulted in a statistically significant higher tensile bond strength (P<0.05. In group 4, 20% of the porcelain facets displayed damage. Conclusion: Etching of the surface with HFL increased the bond strength values. Silane application was recommended to bond a ceramic bracket to the porcelain surface in order to achieve bond strengths that are clinically acceptable.

  11. Dye-enhanced laser fluorescence detection of caries lesions around brackets.

    Science.gov (United States)

    Alencar, Cássio José Fornazari; Braga, Mariana Minatel; de Oliveira, Elisabeth; Nicolau, José; Mendes, Fausto Medeiros

    2009-11-01

    The aim was to evaluate the performance of DIAGNOdent [laser fluorescence(LF) and LFpen] devices enhanced by fluorescent dye in detecting mineral loss around brackets and comparing the inhibitory effect of bonding material on artificial demineralization, and to verify whether LF methods show the same trends of mineral loss. Brackets were bonded to premolar halves with Fuji Ortho LC, Transbond XT, and Ortho Glass LC cements (n = 15). The teeth were soaked in demineralizing solution (pH = 4.8) for 16 days. Mineral loss was calculated by atomic emission spectrometry, and lesions were measured with LF devices with dye [tetrakis N-methylpyridyl porphyrin (TMPyP)]. Groups were compared with regard to LF readings and mineral loss, and performance of caries detection was calculated. Higher mineral loss and LF-TMPyP values occurred in the resin group. LFpen-TMPyP readings were significantly higher in the demineralized groups. Correlation was observed between mineral loss and LF measurements. LF methods are capable of identifying lower demineralization around brackets bonded with resin-modified glass ionomer cements.

  12. Bonding brackets on white spot lesions pretreated by means of two methods

    Directory of Open Access Journals (Sweden)

    Julia Sotero Vianna

    2016-04-01

    Full Text Available Abstract Objective: The aim of this study was to evaluate the shear bond strength (SBS of brackets bonded to demineralized enamel pretreated with low viscosity Icon Infiltrant resin (DMG and glass ionomer cement (Clinpro XT Varnish, 3M Unitek with and without aging. Methods: A total of 75 bovine enamel specimens were allocated into five groups (n = 15. Group 1 was the control group in which the enamel surface was not demineralized. In the other four groups, the surfaces were submitted to cariogenic challenge and white spot lesions were treated. Groups 2 and 3 were treated with Icon Infiltrant resin; Groups 4 and 5, with Clinpro XT Varnish. After treatment, Groups 3 and 5 were artificially aged. Brackets were bonded with Transbond XT adhesive system and SBS was evaluated by means of a universal testing machine. Statistical analysis was performed by one-way analysis of variance followed by Tukey post-hoc test. Results: All groups tested presented shear bond strengths similar to or higher than the control group. Specimens of Group 4 had significantly higher shear bond strength values (p < 0.05 than the others. Conclusion: Pretreatment of white spot lesions, with or without aging, did not decrease the SBS of brackets.

  13. Microleakage under Orthodontic Metal Brackets Bonded with Three Different Bonding Techniques with/without Thermocycling

    Directory of Open Access Journals (Sweden)

    Berahman Sabzevari

    2013-12-01

    Full Text Available Introduction: The aim of this study was to compare the microleakage of beneath the orthodontic brackets bonded with 3 different bonding techniques and evaluate the effect of thermocycling. Methods: One hundred and twenty premolars were randomly divided into 6 groups, received the following treatment: group 1: 37% phosphoric acid gel+Unite primer+Unite adhesive, group 2: 37% phosphoric acid gel+ Transbond XT primer+Transbond XT adhesive, group 3: Transbond plus Self Etching Primer (TSEP+Transbond XT adhesive. Groups 4, 5, and 6 were similar to groups 1, 2, and 3, respectively. Evaluation of microleakage was done following to thermocycling test. After bonding, the specimens were sealed with nail varnish except for 1 mm around the brackets and then stained with 0.5% basic fuchsine. The specimens were sectioned at buccolingual direction in 2 parallel planes and evaluated under a stereomicroscope to determine the amount of microleakage at bracket-adhesive and adhesive-enamel interfaces from gingival and occlusal margins. Results: Microleakage was observed in all groups, and increased significantly after thermocycling at some interfaces of Unite adhesive group and conventional etching+Transbond XT adhesive group, but the increase was not significant in any interface of TSEP group. With or without thermocycling, TSEP displayed more microleakage than other groups. In most groups, microleakage at gingival margin was significantly higher than occlusal margin. Conclusion: Thermocycling and type of bonding technique significantly affect the amount of microleakage.

  14. Dentoalveolar mandibular changes with self-ligating versus conventional bracket systems: A CBCT and dental cast study

    Directory of Open Access Journals (Sweden)

    Marcio Rodrigues de Almeida

    2015-06-01

    Full Text Available OBJECTIVE: The aim of the present study was to compare dentoalveolar changes in mandibular arch, regarding transversal measures and buccal bone thickness, in patients undergoing the initial phase of orthodontic treatment with self-ligating or conventional bracket systems. METHODS: A sample of 25 patients requiring orthodontic treatment was assessed based on the bracket type. Group 1 comprised 13 patients bonded with 0.022-in self-ligating brackets (SLB. Group 2 included 12 patients bonded with 0.022-in conventional brackets (CLB. Cone-beam computed tomography (CBCT scans and a 3D program (Dolphin assessed changes in transversal width of buccal bone (TWBB and buccal bone thickness (BBT before (T1 and 7 months after treatment onset (T2. Measurements on dental casts were performed using a digital caliper. Differences between and within groups were analyzed by Student's t-test; Pearson correlation coefficient was also calculated. RESULTS: Significant mandibular expansion was observed for both groups; however, no significant differences were found between groups. There was significant decrease in mandibular buccal bone thickness and transversal width of buccal bone in both groups. There was no significant correlation between buccal bone thickness and dental arch expansion. CONCLUSIONS: There were no significant differences between self-ligating brackets and conventional brackets systems regarding mandibular arch expansion and changes in buccal bone thickness or transversal width of buccal bone.

  15. Influences of bracket bonding on mutans streptococcus in plaque detected by real time fluorescence-quantitative polymerase chain reaction

    Institute of Scientific and Technical Information of China (English)

    AI Hong; LU Hong-fei; LIANG Huan-you; WU Jian; LI Ruo-lan; LIU Guo-ping; XI Yun

    2005-01-01

    Background Enamel demineralization occurs frequently during orthodontic treatment. In this study, we evaluated the changes of the density of mutans streptococcus (MS) in plaque after bracket bonding and using fluoride adhesive on maxillary incisors by real time fluorescence-quantitative polymerase chain reaction (RT-FQ PCR).Methods The study was designed as a self-paired test. Brackets were bonded with fluoride adhesive on the left side, while non-fluoride adhesive on the right side for each patient. Plaque samples were taken from the surfaces around the brackets of four maxillary incisors before brackets bonding and after the bonding 4 weeks later. The amount of MS was measured by RT-FQ PCR. The data obtained were analyzed statistically using the SPSS 11.5 version and the alpha level was set at 0.05 (2-tailed).Results The amount of MS in plaque increased significantly after bracket bonding (P0.05), and among the incisors using and not using fluoride adhesive (P>0.05).Conclusions The increase of the density of MS in plaque after bracket bonding is one of the etiological factors for enamel demineralization in orthodontic patients. The result of this study did not support what we observed clinically that the incidence of enamel demineralization for lateral incisors was higher than that for central incisors. Using fluoride adhesive for bonding did not affect the amount of MS in plaque in our study. Further study is needed.

  16. Damage of the Interface Between an Orthodontic Bracket and Enamel - the Effect of Some Elastic Properties of the Adhesive Material

    Science.gov (United States)

    Durgesh, B. H.; Alkheraif, A. A.; Al Sharawy, M.; Varrela, J.; Vallittu, P. K.

    2016-01-01

    The aim of this study was to investigate the magnitude of debonding stress of an orthodontic bracket bonded to the enamel with resin systems having different elastic properties. For the same purpose, sixty human premolars were randomly divided into four groups according to the adhesive system used for bonding brackets: G Fix flowable resin (GFI) with Everstick NET (ESN), GFI, G Aenial Universal Flow (GAU) with ESN, and GAU. The brackets were stressed in the occlusogingival direction on a universal testing machine. The values of debonding load and displacement were determined at the point of debonding. The elastic modulus of the tested materials was determined using nanoindentation. An analysis of variance showed a significant difference in the loads required to debond the bracket among the groups tested. The GAU group had the highest elastic modulus, followed by the GFI and ESN groups. ARI (Adhesive Remnant Index) scores demonstrated more remnants of the adhesive material on the bracket surface with adhesives having a higher elastic modulus. Taking into consideration results of the present in-vitro study, it can be concluded that the incorporation of a glass-fiber-reinforced composite resin (FRC) with a low elastic modulus between the orthodontic bracket and enamel increases the debonding force and strain more than with adhesive systems having a higher elastic modulus.

  17. Alterations in plaque accumulation and gingival inflammation promoted by treatment with self-ligating and conventional orthodontic brackets

    Directory of Open Access Journals (Sweden)

    Mauricio de Almeida Cardoso

    2015-04-01

    Full Text Available OBJECTIVE: The aim of the present study was to evaluate, comparatively, the periodontal response during orthodontic treatment performed with self-ligating and conventional brackets. METHODS: Sixteen Caucasian individuals of both sexes, aged between 12 and 16 years old and in permanent dentition were selected. Eight individuals were treated with conventional brackets installed on the lower dental arch and self-ligating brackets on the upper arch. Another eight individuals received self-ligating brackets in the lower arch and conventional brackets in the upper arch. The subjects received material and instructions for oral hygiene. Visible plaque index (VPI, gingival bleeding index (GBI and clinical attachment level (CAL were evaluated just after installation of orthodontic appliances, and 30, 60 and 180 days later. Mann-Whitney test was used to compare differences between groups (self-ligating and conventional, two-way ANOVA followed by Tukey's test was used to assess CAL at each site of each tooth. Significance level was set at 5%. RESULTS: No significant changes were found with regard to the assessed parameters (VPI, GBI and CAL in either one of the systems. CONCLUSION: No significant changes were found with regard to the periodontal response to orthodontic treatment for the variables assessed and between subjects receiving passive self-ligating and conventional brackets. All individuals had received oral hygiene instructions and had their periodontal conditions monitored.

  18. Shear bond strength and debonding characteristics of metal and ceramic brackets bonded with conventional acid-etch and self-etch primer systems: An in-vivo study

    Science.gov (United States)

    Mirzakouchaki, Behnam; Sharghi, Reza; Shirazi, Samaneh; Moghimi, Mahsan; Shahrbaf, Shirin

    2016-01-01

    Background Different in-vitro studies have reported various results regarding shear bond strength (SBS) of orthodontic brackets when SEP technique is compared to conventional system. This in-vivo study was designed to compare the effect of conventional acid-etching and self-etching primer adhesive (SEP) systems on SBS and debonding characteristics of metal and ceramic orthodontic brackets. Material and Methods 120 intact first maxillary and mandibular premolars of 30 orthodontic patients were selected and bonded with metal and ceramic brackets using conventional acid-etch or self-etch primer system. The bonded brackets were incorporated into the wire during the study period to simulate the real orthodontic treatment condition. The teeth were extracted and debonded after 30 days. The SBS, debonding characteristics and adhesive remnant indices (ARI) were determined in all groups. Results The mean SBS of metal brackets was 10.63±1.42 MPa in conventional and 9.38±1.53 MPa in SEP system, (P=0.004). No statistically significant difference was noted between conventional and SEP systems in ceramic brackets. The frequency of 1, 2 and 3 ARI scores and debonding within the adhesive were the most common among all groups. No statistically significant difference was observed regarding ARI or failure mode of debonded specimens in different brackets or bonding systems. Conclusions The SBS of metal brackets bonded using conventional system was significantly higher than SEP system, although the SBS of SEP system was clinically acceptable. No significant difference was found between conventional and SEP systems used with ceramic brackets. Total SBS of metal brackets was significantly higher than ceramic brackets. Due to adequate SBS of SEP system in bonding the metal brackets, it can be used as an alternative for conventional system. Key words:Shear bond strength, Orthodontic brackets, Adhesive remnant index, self-etch. PMID:26855704

  19. Orthodontic brackets in high field MR imaging: experimental evaluation of magnetic field interactions at 3.0 tesla; Kieferorthopaedische Brackets in der Hochfeld-Magnetresonanz-Tomographie: Experimentelle Beurteilung magnetischer Anziehungs- und Rotationskraefte bei 3 Tesla

    Energy Technology Data Exchange (ETDEWEB)

    Kemper, J.; Adam, G. [Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie, Universitaetsklinikum Eppendorf, Hamburg (Germany); Klocke, A.; Kahl-Nieke, B. [Poliklinik fuer Kieferorthopaedie, Universitaetsklinikum Eppendorf, Hamburg (Germany)

    2005-12-15

    Purpose: To evaluate static magnetic field interactions for 32 commonly used orthodontic brackets in a 3.0 T magnetic resonance imaging (MRI) system. Materials and methods: 32 orthodontic brackets consisting of a steel alloy (n=27), a cobalt-chromium alloy (n=2), ceramic (n=1), ceramic with a steel slot (n=1), and titanium (n=1) from 13 different manufacturers were tested for magnetic field interactions in a static magnetic field at 3.0 T (Gyroscan Intera 3.0 T, Philips Medical Systems, Best, Netherlands). The magnetic deflection force F{sub Z} [mN] was evaluated by determining the deflection angle {beta}[ ] using the established deflection angle test according to the ASTM guidelines. The magnetic-field-induced rotational force F{sub rot} or torque was qualitatively determined using a 5-point grading scale (0: no torque; +4: very strong torque). Results: In 18 of the 32 brackets, the deflection angle {beta} was found to be > 45 and the translational force exceeded the gravitational force F{sub G} on the particular bracket (F{sub Z}: 1.2-45.7 mN). The translational force F{sub Z} was found to be up to 68.5 times greater than the gravitational force F{sub G} (F{sub Z}/F{sub G}: 1.4-68.5). The rotational force F{sub rot} was correspondingly high (+3/+4) for those brackets. For the remaining 14 objects, the deflection angles were < 45 and the torque measurements ranged from 0 to +2. The static magnetic field did not affect the titanium bracket and the ceramic bracket. No measurable translational and rotational forces were found. (orig.)

  20. Effects of fluoride release from orthodontic bonding materials on nanomechanical properties of the enamel around orthodontic brackets

    Directory of Open Access Journals (Sweden)

    Seyed Hamid Raji

    2014-01-01

    Full Text Available Background: The aim of the present study is to evaluate the effects of a fluoride-releasing composite resin bonding material on reducing enamel demineralization underneath and around orthodontic brackets and compare that with a conventional adhesive system. Materials and Methods: Buccal surfaces of 10 intact extracted premolar teeth were divided into two parts with nail varnish and stainless steel brackets were randomly bonded by two resin composite systems: (Transbond XT and (Transbond XT plus Color Change (3M, Unitek, Monrovia, CA, USA on two sides of the teeth and then samples were placed in a demineralization solution. It is claimed that the second system has the ability of fluoride release. Elastic modulus and hardness of enamel were measured with nanoindentation test in 6 depths in 1-36 μm from the enamel surface and in 7 regions: Control (intact enamel surface, underneath the brackets and also 50 and 100 μm from the brackets edge. These nanomechanical features were evaluated in different regions and depths using analysis of variance and paired t-test (P < 0.05. Results: Considerable difference can be seen in different depths and regions in terms of hardness and elastic modulus. The region under the bracket with fluoridated adhesive shows similar results with intact enamel, whereas these parameters in fluoride less side show a significant reduction (P < 0.05. Conclusion: Results show that use of resin composite bonding system with the ability of fluoride release for bracket bonding, may reduce demineralization of enamel around brackets during orthodontic treatment.

  1. Symbolic algorithms for the computation of Moshinsky brackets and nuclear matrix elements

    Science.gov (United States)

    Ursescu, D.; Tomaselli, M.; Kuehl, T.; Fritzsche, S.

    2005-12-01

    To facilitate the use of the extended nuclear shell model (NSM), a FERMI module for calculating some of its basic quantities in the framework of MAPLE is provided. The Moshinsky brackets, the matrix elements for several central and non-central interactions between nuclear two-particle states as well as their expansion in terms of Talmi integrals are easily given within a symbolic formulation. All of these quantities are available for interactive work. Program summaryTitle of program:Fermi Catalogue identifier:ADVO Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVO Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing provisions:None Computer for which the program is designed and others on which is has been tested:All computers with a licence for the computer algebra package MAPLE [Maple is a registered trademark of Waterloo Maple Inc., produced by MapleSoft division of Waterloo Maple Inc.] Instalations:GSI-Darmstadt; University of Kassel (Germany) Operating systems or monitors under which the program has beentested: WindowsXP, Linux 2.4 Programming language used:MAPLE 8 and 9.5 from MapleSoft division of Waterloo Maple Inc. Memory required to execute with typical data:30 MB No. of lines in distributed program including test data etc.:5742 No. of bytes in distributed program including test data etc.:288 939 Distribution program:tar.gz Nature of the physical problem:In order to perform calculations within the nuclear shell model (NSM), a quick and reliable access to the nuclear matrix elements is required. These matrix elements, which arise from various types of forces among the nucleons, can be calculated using Moshinsky's transformation brackets between relative and center-of-mass coordinates [T.A. Brody, M. Moshinsky, Tables of Transformation Brackets, Monografias del Instituto de Fisica, Universidad Nacional Autonoma de Mexico, 1960] and by the proper use of the nuclear states in different coupling notations

  2. Effect of self-etching primer/adhesive and conventional bonding on the shear bond strength in metallic and ceramic brackets

    Science.gov (United States)

    Kimyai, Soodabeh; Hydari, Mahboubeh; Shahrbaf, Shirin; Mirzakouchaki-Boroujeni, Parvin

    2012-01-01

    Introduction: Bracket debonding from the tooth surface is a common problem in fixed orthodontics. The aims of the present study were to assess the bond strength and failure sites in two ways of bonding technique, with metallic and ceramic brackets. Material and Methods: One hundred premolars were assigned to 4 groups of 25 each: Group A, metallic brackets/ conventional procedure; Group B, metallic brackets/Transbond XT; Group C, ceramic brackets/conventional procedure; and Group D, ceramic brackets/Transbond XT. Transbond XT composite paste was used for bracket bonding and cured by conventional light-cure device. Specimens were subjected to thermocycling. One week after bonding shearing force was applied to the bracket-tooth interface. Bonding failure site optically examined using a stereomicroscope under 10 × magnifications and scoring was done using the adhesive remnant index (ARI). Data were subjected to analysis of One-way variance, Tukey post hoc, Chi-square and Spearman’s tests. Results: Mean bond strength (in MPa) were: group A=9.2, group B=8.5, group C=6.2 and group D=5.7. Bond strength differences between groups A and B, and between C and D were not significant, (pceramic ones and the selfetching primer produce fewer bonds than the conventional method (clinically acceptable). A positive correlation found between changes in shearing bond strength and ARI. Key words: Acid etching, adhesive remnant index, orthodontic brackets, self-etching primer, shearing bond strength. PMID:21743430

  3. The effect of herbal teas on the shear bond strength of orthodontic brackets.

    Science.gov (United States)

    Ulusoy, Cagri; Müjdeci, Arzu; Gökay, Osman

    2009-08-01

    The present study was conducted to evaluate the effects of some types of herbal tea on the shear bond strength (SBS) of orthodontic brackets to enamel surfaces. The brackets were bonded with Transbond XT to 90 extracted human premolar teeth and divided equally into six groups, that is, black, mint-mate herbal, mint-lemon herbal, and rosehip fruit tea and two control groups, Coca-Cola and distilled water. All groups were conditioned for three 5-minute sessions with equal intervening intervals for 90 days. The initial pH, SBS, and adhesive remnant index (ARI) of the groups were evaluated and the data were analysed statistically by Kruskal-Wallis and Mann-Whitney U-tests, one-way analysis of variance, and Duncan and Z-tests, respectively. Rosehip fruit tea (2.4 +/- 0.07) and Coca-Cola (2.5 +/- 0.05) had the lowest pH values. Coca-Cola (6.04 +/- 1.11 MPa) and rosehip fruit tea (7.26 +/- 1.11 MPa) significantly reduced the SBS to enamel (P 0.05). Except for the Coca-Cola group (ARI score = 0), fracture sites for all other groups were similar with the majority of bond failures at the enamel-adhesive interface (ARI score = 1). Although this experiment could not completely replicate the complex oral environment, it seems to confirm that Coca-Cola and rosehip fruit tea may be a causative factor in bracket-enamel bonding failure.

  4. CO2 laser as auxiliary in the debonding of ceramic brackets.

    Science.gov (United States)

    Macri, Rodrigo Teixeira; de Lima, Fabrício Augusto; Bachmann, Luciano; Galo, Rodrigo; Romano, Fábio Lourenço; Borsatto, Maria Cristina; Matsumoto, Mírian Aiko Nakane

    2015-09-01

    This study evaluated the temperature in the bonding composite and in the pulp chamber, the shear bond strength after the irradiation of CO2 lasers, and the Adhesive Remnant Index (ARI) after debonding of ceramic bracket. A hundred and five premolars were used: 30 to evaluate the temperature and 75 to test the resistance to shear and the ARI. To assess the temperature, different irradiation times (3 and 5 s), pulse duration (0.001 and 0.003 s), and output power (5, 8, and 10 W) were tested (total of 12 groups). During all the irradiation, specimens were immersed in thermal bath water at 37 °C. In the test and ARI evaluation, premolars were divided into five groups (n = 15) and were submitted to the following regimens of CO2 laser irradiation: I (5 W, pulse duration = 0.01 s, application time = 3 s), II (5 W, 0.03 s, 3 s), III (8 W, 0.01 s, 3 s), and IV (1 0 W, 0.01 s, 3 s). Group C (control) was not subjected to irradiation. ARI was measured after debonding of the bracket. Following irradiation of the lasers, the pulpal temperature was not higher than 5.5 °C in four of the study groups. Results were submitted to the ANOVA and Duncan's test. CO2 laser irradiation regimen IV was one in which the strength of debonding is 7.33 MPa. Therefore, CO2 laser may aid removal of ceramic brackets; it decreased the bond strength without increasing the excessive temperature excessively.

  5. Tensile Bond Strength of Metal Bracket Bonding to Glazed Ceramic Surfaces With Different Surface Conditionings

    Directory of Open Access Journals (Sweden)

    M. Imani

    2011-12-01

    Full Text Available Objective: The objective of this study was to compare the tensile bond strength of metal brackets bonding to glazed ceramic surfaces using three various surface treatments.Materials and Methods: Forty two glazed ceramic disks were assigned to three groups. In the first and second groups the specimens were etched with 9.5% hydrofluoric acid (HFA. Subsequently in first group, ceramic primer and adhesive were applied, but in second group a bonding agent alone was used. In third group, specimens were treated with 35% phosphoric acid followed by ceramic primerand adhesive application. Brackets were bonded with light cure composites. The specimens were stored in distilled water in the room temperature for 24 hours and thermocycled 500 times between 5°C and 55°C. The universal testing machine was used to test the tensile bond strength and the adhesive remenant index scores between three groups was evaluated. The data were subjected to one-way ANOVA, Tukey and Kruskal-Wallis tests respectively.Results: The tensile bond strength was 3.69±0.52 MPa forfirst group, 2.69±0.91 MPa for second group and 3.60±0.41 MPa for third group. Group II specimens showed tensile strength values significantly different from other groups (P<0.01.Conclusion: In spite of limitations in laboratory studies it may be concluded that in application of Scotch bond multipurpose plus adhesive, phosphoric acid can be used instead of HFA for bonding brackets to the glazed ceramic restorations with enough tensile bond strength.

  6. Enamel surface evaluation after bracket debonding and different resin removal methods

    Directory of Open Access Journals (Sweden)

    Michele Machado Vidor

    2015-04-01

    Full Text Available OBJECTIVE: To assess enamel surface under scanning electron microscopy (SEM after resin removal and enamel polishing procedures following brackets debonding, as well as compare the time required for these procedures. METHODS: A total of 180 deciduous bovine incisors were used. The enamel surface of each tooth was prepared and brackets were bonded with light cured Transbond XT composite resin. Brackets were removed in a testing machine. The samples were randomized and equally distributed into nine groups according to the resin removal and polishing technique: Group 1, 30-blade tungsten carbide bur in high speed; Group 2, 30-blade tungsten carbide bur in high speed followed by a sequence of 4 Sof-lex polishing discs (3M; Group 3, 30-blade tungsten carbide bur in high speed followed by Enhance tips (Dentsply. All groups were subdivided into (a unpolished; (b polished with aluminum oxide paste; and (c polished with water slurry of fine pumice. Subsequently, the enamel surface was assessed and statistical analysis was carried out. RESULTS: There were statistically significant differences in enamel roughness and removal time among all groups. Groups 3a, 3b and 3c appeared to be the most efficient methods of removing resin with low damages to enamel. Groups 2a, 2b and 2c were the most time consuming procedures, and Group 2a caused more damages to enamel. CONCLUSION: The suggested protocol for resin removal is the 30-blade tungsten carbide bur in high speed followed by Enhance tips and polishing with aluminum oxide paste. This procedure seems to produce less damages and is less time consuming.

  7. Effect of different methods of enamel conditioning on bond strength of orthodontic brackets

    Directory of Open Access Journals (Sweden)

    Davari AR

    2007-01-01

    Full Text Available Background and Aim: With the introduction of different bondable restorative materials in dentistry, various methods have been suggested to enhance the polymerization and shear bond strength of these materials. The aim of this study was to determine the effects of different methods of enamel conditioning on bond strength of orthodontic brackets and on the bracket/ adhesive failure mode. Materials and Methods: In this experimental in vitro study, brackets were bonded to thirty-six bovine incisor teeth with different protocols according to the manufacturer's instructions as follows: Group 1: conventional multistep adhesive (n=12; Group 2: self-etching primer system (n=12; Group 3: acid+self-etching primer system (n=12. Specimens were loaded in a universal testing machine (Instron, Canton and Mass and the mode of failure was recorded. Data were analyzed by ANOVA and Kruskall-Wallis tests with p<0.05 as the limit of significance. Results: The mean shear bond strength was 11.7 ± 4.2, 10.5 ± 4.4, and 10.9 ± 4.8 MPa for group 1, 2, and 3 respectively. There was no significant difference in bond strength among the three groups (P=0.800. No significant difference was observed among the three groups with respect to residual adhesive on the enamel surfaces (P=0.554. Conclusion: Based on the results of the present study, the use of self-etching primers may be an alternative to conventional phosphoric acid pre-treatment in orthodontic bonding.

  8. The Effect of Different Soft Drinks on the Shear Bond Strength of Orthodontic Brackets

    Directory of Open Access Journals (Sweden)

    M Omid Khoda

    2012-01-01

    Full Text Available Objective: It is proved that acidic soft drinks that are commonly used, have an adverse effect on dental structures, and may deteriorate oral heath of our patients and orthodontic appliances. The aim of this study was to compare the effect of yoghurt drink with other soft drinks on the shear bond strength of orthodontic brackets.Materials and Methods: Seventy-five first premolar teeth extracted for orthodontic purposes were selected and standard twin metal brackets were bonded on the center of buccal surface with No-Mix composite. The teeth were thermocycled for 625 cycles and randomly divided into five groups of artificial saliva, carbonated yoghurt drink with lactic acid base, non-carbonated yoghurt drink with lactic acid base, 7 up with citric acid base and Pepsi with phosphoric acid base. In all groups, the teeth were immersed in liquid for five-minute sessions three times with equal intervening intervals for 3 months. SBS was measured by a universal testing machine with a speed of 0.5mm/min. Data was analyzed statistically by one-way ANOVA.Results: The results showed that mean values for the shear bond strength of carbonated yoghurt drinks, non-carbonated yoghurt drinks, 7up and Pepsi groups were 12.98(+_2.95, 13.26(+_4.00, 16.11(+_4.89, 14.73(+_5.10, respectively. There was no statistically significant difference among the groups (P-value= 0.238Conclusion: Soft drinks used in this study did not decrease the bond strength of the brackets bonded with this specific type of composite.

  9. Fluoride-Releasing Materials to Prevent White Spot Lesions around Orthodontic Brackets: A Systematic Review.

    Science.gov (United States)

    Nascimento, Patrícia Layane de Menezes Macêdo; Fernandes, Micaelle Tenório Guedes; Figueiredo, Fabricio Eneas Diniz de; Faria-E-Silva, André Luis

    2016-01-01

    The relation between orthodontic fixed appliances use and enamel demineralization is well established. Different preventive approaches have been suggested to this problem, but controversy remains about which is the best. The aim of this study was to perform a systematic review of clinical trials that investigated the effectiveness of materials containing fluorides to lute brackets or cover the bonding interface in order to inhibit the development and progression of white spot lesions. The null hypothesis was that fluoride materials do not affect the incidence of white spot lesions around brackets. A MEDLINE search was conducted for randomized clinical trials evaluating the development of white spot lesions in patients using fixed orthodontic appliances, followed by meta-analysis comparing the results for patients for whom dental materials containing fluorides were used (experimental group) to those for whom these materials were not used (control group). The pooled relative risk of developing white spot lesions for the experimental group was 0.42 (95% confidence interval: 0.25 to 0.72); hence, when fluoride-releasing materials are used, the patient has 58% less risk of white spot lesion development. Regarding white spot lesion extent, the pooled mean difference between the experimental and control groups was not statistically significant (-0.12; 95% confidence interval: -0.29 to 0.04). In conclusion, the results of the present systematic review suggest that fluoride-releasing materials can reduce the risk of white spot lesions around brackets. However, when white spot lesions had already occurred, there is no evidence that fluoride-releasing materials reduce the extent of these lesions.

  10. Effectiveness of fluoride sealant in the prevention of carious lesions around orthodontic brackets: an OCT evaluation

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    Matheus Melo Pithon

    2015-12-01

    Full Text Available Abstract Objective: This article aimed to evaluate in vitro the efficiency of Pro Seal fluoride sealant application in the prevention of white spot lesions around orthodontic brackets. Material and Methods: Brackets were bonded to the buccal surface of bovine incisors, and five groups were formed (n = 15 according to the exposure of teeth to oral hygiene substances and the application of enamel sealant: G1 (control, only brushing was performed with 1.450 ppm fluoride; G2 (control brushing associated with the use of mouthwash with 225 ppm fluoride; G3, only Pro Seal sealant application was performed with 1.000 ppm fluoride; G4 Pro Seal associated with brushing; G5 Pro Seal associated with brushing and mouthwash. Experimental groups alternated between pH cycling and the procedures described. All specimens were kept at a temperature of 37 °C throughout the entire experiment. Both brushing and immersion in solutions were performed within a time interval of one minute, followed by washing in deionized water three times a day for 28 days. Afterwards, an evaluation by Optical Coherence Tomography (OCT of the spectral type was performed. In each group, a scanning exam of the white spot lesion area (around the sites where brackets were bonded and depth measurement of carious lesions were performed. Analysis of variance (ANOVA was applied to determine whether there were significant differences among groups. For post hoc analysis, Tukey test was used. Results: There was statistically significant difference between groups 1 and 2 (p = 0.003, 1 and 3 (p = 0.008, 1 and 4 (p = 0.000 and 1 and 5 (p = 0.000. The group in which only brushing was performed (Group 1 showed deeper enamel lesion. Conclusion: Pro Seal sealant alone or combined with brushing and/or brushing and the use of a mouthwash with fluoride was more effective in protecting enamel, in comparison to brushing alone.

  11. Photoelastic analysis of stress generated by wires when conventional and self-ligating brackets are used: A pilot study

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    Guilherme Caiado Sobral

    2014-10-01

    Full Text Available OBJECTIVE: By means of a photoelastic model, this study analyzed the stress caused on conventional and self-ligating brackets with expanded arch wires. METHOD: Standard brackets were adhered to artificial teeth and a photoelastic model was prepared using the Interlandi 19/12 diagram as base. Successive activations were made with 0.014-in and 0.018-in rounded cross section Nickel-Titanium wires (NiTi and 0.019 x 0.025-in rectangular stainless steel wires all of which made on 22/14 Interlandi diagram. The model was observed on a plane polariscope - in a dark field microscope configuration - and photographed at each exchange of wire. Then, they were replaced by self-ligating brackets and the process was repeated. Analysis was qualitative and observed stress location and pattern on both models analyzed. CONCLUSIONS: Results identified greater stress on the region of the apex of premolars in both analyzed models. Upon comparing the stress between models, a greater amount of stress was found in the model with conventional brackets in all of its wires. Therefore, the present pilot study revealed that alignment of wires in self-ligating brackets produced lower stress in periodontal tissues in expansive mechanics.

  12. The Brackets Design and Stress Analysis of a Refinery's Hot Water Pipeline

    Science.gov (United States)

    Zhou, San-Ping; He, Yan-Lin

    2016-05-01

    The reconstruction engineering which reconstructs the hot water pipeline from a power station to a heat exchange station requires the new hot water pipeline combine with old pipe racks. Taking the allowable span calculated based on GB50316 and the design philosophy of the pipeline supports into account, determine the types and locations of brackets. By analyzing the stresses of the pipeline in AutoPIPE, adjusting the supports at dangerous segments, recalculating in AutoPIPE, at last determine the types, locations and numbers of supports reasonably. Then the overall pipeline system will satisfy the requirement of the ASME B31.3.

  13. Sistemas de brackets de baja fricción en ortodoncia clínica

    OpenAIRE

    2011-01-01

    Los sistemas de brackets de baja fricción reducen la fricción en comparación con los convencionales. La fricción se define como la fuerza resistencia entre dos objetos en movimiento que entran en contacto. Junto con la fijación (binding) y la muesca (notching), la fricción es responsable de la resistencia de deslizamiento que se observa en ortodoncia en las etapas de alineado, nivelado y cierre de espacios. Se ha establecido que la a...

  14. Assessment of pain experience in adults and children after bracket bonding and initial archwire insertion

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    Marcio José da Silva Campos

    2013-10-01

    Full Text Available INTRODUCTION: Ninety five percent of orthodontic patients routinely report pain, due to alterations in the periodontal ligament and surrounding soft tissues, with intensity and prevalence varying according to age. OBJECTIVE: This study aimed to assess toothache and buccal mucosal pain in adults and children during two initial phases of the orthodontic treatment. METHODS: The intensity of toothache and buccal mucosal pain reported by 20 patients, 10 children (11-13 years and 10 adults (18-37 years was recorded with the aid of a Visual Analog Scale (VAS, during 14 days - 7 days with bonded brackets only and 7 days with the initial archwire inserted. RESULTS: There was no significant difference in pain intensity among adults and children. After bracket bonding, 50% of the children and 70% of the adults reported pain. 70% of both groups reported pain after initial archwire insertion. While adults reported constant, low intensity, buccal mucosal pain, the children showed great variation of pain intensity, but with a trend towards decreasing pain during the assessment period. After initial archwire insertion the peaks of toothache intensity and prevalence occurred 24 hours in children and 48 hours in adults. CONCLUSIONS: In general, children reported pain less frequently than adults did, though with greater intensity.

  15. Effect of adhesive remnant removal on enamel topography after bracket debonding

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    Larissa Adrian Meira Cardoso

    2014-12-01

    Full Text Available INTRODUCTION: At orthodontic treatment completion, knowledge about the effects of adhesive remnant removal on enamel is paramount.OBJECTIVE: This study aimed at assessing the effect of different adhesive remnant removal methods on enamel topography (ESI and surface roughness (Ra after bracket debonding and polishing.METHODS: A total of 50 human premolars were selected and divided into five groups according to the method used for adhesive remnant removal: high speed tungsten carbide bur (TCB, Sof-Lex discs (SL, adhesive removing plier (PL, ultrasound (US and Fiberglass burs (FB. Metal brackets were bonded with Transbond XT, stored at 37oC for 24 hours before debonding with adhesive removing plier. Subsequently, removal methods were carried out followed by polishing with pumice paste. Qualitative and quantitative analyses were conducted with pre-bonding, post-debonding and post-polishing analyses. Results were submitted to statistical analysis with F test (ANOVA and Tukey's (Ra as well as with Kruskal-Wallis and Bonferroni tests (ESI (P < 0.05.RESULTS: US Ra and ESI were significantly greater than TCB, SL, PL and FB. Polishing minimized Ra and ESI in the SL and FB groups.CONCLUSION: Adhesive remnant removal with SL and FB associated with polishing are recommended due to causing little damage to the enamel.

  16. CO2 laser conditioning of porcelain surfaces for bonding metal orthodontic brackets.

    Science.gov (United States)

    Ahrari, Farzaneh; Heravi, Farzin; Hosseini, Mohsen

    2013-07-01

    Bonding to porcelain remains to be a challenge in orthodontic treatments. The objective of this study was to evaluate the effect of CO2 laser conditioning of porcelain surfaces on shear bond strength (SBS) of orthodontic brackets. Eighty feldspathic porcelain specimens were divided into four groups of 20. In each group, half of the porcelain surfaces were deglazed, while the others remained glazed. The specimens in groups 1 to 3 were treated with a fractional CO2 laser for 10 s using 10 mJ of energy, frequency of 200 Hz and powers of 10 W (group 1), 15 W (group 2) and 20 W (group 3). In group 4, a 9.6 % hydrofluoric (HF) acid gel was used for 2 min. A silane coupling agent was applied before bracket bonding, and the SBS was measured with a universal testing machine after 24 h. Deglazing caused significant increase in SBS of laser treated porcelain surfaces (p porcelain.

  17. Effects of surface treatment of provisional crowns on the shear bond strength of brackets

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    Josiane Xavier de Almeida

    2013-08-01

    Full Text Available OBJECTIVE: To assess the adhesive resistance of metallic brackets bonded to temporary crowns made of acrylic resin after different surface treatments. METHODS: 180 specimens were made of Duralay and randomly divided into 6 groups (n = 30 according to surface treatment and bonding material: G1 - surface roughening with Soflex and bonding with Duralay; G2 - roughening with aluminum oxide blasting and bonding with Duralay; G3 - application of monomer and bonding with Duralay; G4 - roughening with Soflex and bonding with Transbond XT; G5 - roughening with aluminum oxide blasting and bonding with Transbond XT and G6: application of monomer and bonding with Transbond. The results were statistically assessed by ANOVA/Games-Howell. RESULTS: The means (MPa were: G1= 18.04, G2= 22.64, G3= 22.4, G4= 9.71, G5= 11.23, G6= 9.67. The Adhesive Remnant Index (ARI ranged between 2 and 3 on G1, G2 and G3 whereas in G4, G5 and G6 it ranged from 0 to 1, showing that only the material affects the pattern of adhesive flaw. CONCLUSION: The surface treatment and the material influenced adhesive resistance of brackets bonded to temporary crowns. Roughening by aluminum blasting increased bond strength when compared to Soflex, in the group bonded with Duralay. The bond strength of Duralay acrylic resin was superior to that of Transbond XT composite resin.

  18. Stretched graphene tented by polycaprolactone and polypyrrole net-bracket for neurotransmitter detection

    Science.gov (United States)

    Wang, Zhenzhen; Ying, Ye; Li, Li; Xu, Ting; Wu, Yiping; Guo, Xiaoyu; Wang, Feng; Shen, Haojie; Wen, Ying; Yang, Haifeng

    2017-02-01

    A net-bracket built out from the core@shell structure of chemically oxidized polypyrrole (PPy) coated electrospun polycaprolactone (PCL) nanofibers, and the following surface modification of a thin layer of positively charged poly(dimethyl diallyl ammonium chloride) (PDDA) has been applied for stretching the reduced graphene oxide (RGO) sheets to some extent with the electrochemical deposition method. The as-formed RGO/PDDA/PCL@PPy nanocomposites were investigated by using scanning electron microscopy, transmission electron microscope, X-ray diffraction and Raman spectroscopy. The graphene tented by the net-bracket showed remarkable electrocatalytic properties in detecting the neurotransmitter dopamine (DA). Low detection limit of 0.34 μM (S/N = 3) with the wide linear detection range from 4 μM to 690 μM was obtained. The successful determination of DA in real urine samples and DA injection were achieved. Such attractive fabrication strategy can be extended to make other graphene sheet-based sensors.

  19. MEDICION IN VITRO DE LA FUERZA DE FRICCIÓN EN DUPLAS ARCO-BRACKET CON ANGULACIÓN

    OpenAIRE

    Murillo Mora, Emmanuel

    2012-01-01

    En ortodoncia se utilizan técnicas que buscan un máximo control sobre el movimiento de los dientes. Uno de los múltiples factores a considerar en la selección del material, es optar uno que genere menor fuerza friccional.(23). La reducción de la fricción es una de las metas para la nueva generación de bracket. Se investigó la fuerza friccional de 3 tipos de bracket de diferentes marcas comerciales siendo uno de autoligado (Smart Clip) y los otros con eslastomero, en este cas...

  20. Report: Discussion on the development of nano Ag/TiO2 coating bracket and its antibacterial property and biocompatibility in orthodontic treatment.

    Science.gov (United States)

    Zhang, Ronghe; Zhang, Weiwei; Bai, Xueyan; Song, Xiaotong; Wang, Chunyan; Gao, Xinxin; Tian, Xubiao; Liu, Fengzhen

    2015-03-01

    This paper aims to explore the antibacterial property of nano Ag/TiO2 coating bracket for the common bacteria in oral cavity, and discuss its biocompatibility. Micro morphology in the surface of nano Ag/TiO2 coating bracket was detected by scanning electron microscope (SEM), and surface roughness of ordinary mental bracket, nano TiO2 coating bracket and nano Ag/TiO2 coating bracket were measured. First, antibacterial property of nano Ag/TiO2 coating bracket on the common bacteria in oral cavity was studied by sticking membrane method. Secondly, bonding strength of nano TiO2 coating and nano Ag/TiO2 coating bracket in groups were detected by scratching test. The result showed that, the synthetic nano Ag/TiO2 coating was nanogranular films with rigorous organizational structure, presenting as smooth and clean surface, and antibacterial rate of nano Ag/TiO2 coating for the common bacteria in oral cavity for 20 min was more than 79% in the dark. All the findings suggested that, nano Ag/TiO2 coating bracket not only has antibacterial effect but also has good biocompatibility, therefore, it can satisfy the clinical request of orthodontic treatment.

  1. Comparison of Self-Etch Primers with Conventional Acid Etching System on Orthodontic Brackets

    Science.gov (United States)

    Zope, Amit; Zope-Khalekar, Yogita; Chitko, Shrikant S.; Kerudi, Veerendra V.; Patil, Harshal Ashok; Jaltare, Pratik; Dolas, Siddhesh G

    2016-01-01

    Introduction The self-etching primer system consists of etchant and primer dispersed in a single unit. The etching and priming are merged as a single step leading to fewer stages in bonding procedure and reduction in the number of steps that also reduces the chance of introduction of error, resulting in saving time for the clinician. It also results in smaller extent of enamel decalcification. Aim To compare the Shear Bond Strength (SBS) of orthodontic bracket bonded with Self-Etch Primers (SEP) and conventional acid etching system and to study the surface appearance of teeth after debonding; etching with conventional acid etch and self-etch priming, using stereomicroscope. Materials and Methods Five Groups (n=20) were created randomly from a total of 100 extracted premolars. In a control Group A, etching of enamel was done with 37% phosphoric acid and bonding of stainless steel brackets with Transbond XT (3M Unitek, Monrovia, California). Enamel conditioning in left over four Groups was done with self-etching primers and adhesives as follows: Group B-Transbond Plus (3M Unitek), Group C Xeno V+ (Dentsply), Group D-G-Bond (GC), Group E-One-Coat (Coltene). The Adhesive Remnant Index (ARI) score was also evaluated. Additionally, the surface roughness using profilometer were observed. Results Mean SBS of Group A was 18.26±7.5MPa, Group B was 10.93±4.02MPa, Group C was 6.88±2.91MPa while of Group D was 7.78±4.13MPa and Group E was 10.39±5.22MPa respectively. In conventional group ARI scores shows that over half of the adhesive was remaining on the surface of tooth (score 1 to 3). In self-etching primer groups ARI scores show that there was no or minor amount of adhesive remaining on the surface of tooth (score 4 and 5). SEP produces a lesser surface roughness on the enamel than conventional etching. However, statistical analysis shows significant correlation (p<0.001) of bond strength with surface roughness of enamel. Conclusion All groups might show clinically

  2. SHEAR BOND STRENGTH OF BRACKETS BONDED TO PORCELAIN SURFACE: IN VITRO STUDY

    Directory of Open Access Journals (Sweden)

    Fidan Alakuş Sabuncuoğlu

    2016-01-01

    Full Text Available Purpose: To compare the effects of different porcelain surface treatment methods on the shear bond strength (SBS and fracture mode of orthodontic brackets. Materials and Methods: Seventy feldspathic porcelain disk samples mounted in acrylic resin blocks were divided into seven groups (n=10 according to type of surface treatment: I, Diamond bur; II, Orthosphoric acid (OPA; III, hydrofluoric acid (HFA; IV, sandblasted with aluminum oxide (SB; V, SB+HFA; VI, Neodymium:yttrium-aluminum-garnet (Nd:YAG laser; VII, Erbium:yttrium-aluminum-garnet (Er:YAG laser. Brackets were affixed to treated all-porcelain surfaces with a silane bonding agent and adhesive resin and subjected to SBS testing. Specimens were evaluated according to the adhesive remnant index (ARI, and failure modes were assessed quantitatively under a stereomicroscope and morphologically under a scanning electron microscope (SEM. Statistical analysis was performed using one-way analysis of variance and the post-hoc Tukey test, with the significance level set at 0.05. Results: The highest SBS values were observed for Group V, with no significant difference between Groups V and III. SBS values for Group I were significantly lower than those of all other groups tested. The porcelain/resin interface was the most common site of failure in Group V (40% and Group III (30%, whereas other groups showed various types of bond failure, with no specific location pre-dominating, but with some of the adhesive left on the porcelain surfaces (ARI scores 2 or 3 in most cases. Conclusion: The current findings indicate that a diamond bur alone is unable to sufficiently etch porcelain surfaces for bracket bonding. Moreover, SB and HFA etching used in combination results in a significantly higher shear-bond strength than HFA or SB alone. Finally, laser etching with either an Nd:YAG or Er:YAG laser was found to be more effective and less time-consuming than both HFA acid and SB for the treatment of deglazed

  3. Formulation of singular theories in a partial Hamiltonian formalism using a new bracket and multi-time dynamics

    Science.gov (United States)

    Duplij, Steven

    2015-09-01

    A formulation of singular classical theories (determined by degenerate Lagrangians) without constraints is presented. A partial Hamiltonian formalism in the phase space having an initially arbitrary number of momenta (which can be smaller than the number of velocities) is proposed. The equations of motion become first-order differential equations, and they coincide with those of multi-time dynamics, if a certain condition is imposed. In a singular theory, this condition is fulfilled in the case of the coincidence of the number of generalized momenta with the rank of the Hessian matrix. The noncanonical generalized velocities satisfy a system of linear algebraic equations, which allows an appropriate classification of singular theories (gauge and nongauge). A new antisymmetric bracket (similar to the Poisson bracket) is introduced, which describes the time evolution of physical quantities in a singular theory. The origin of constraints is shown to be a consequence of the (unneeded in our formulation) extension of the phase space, when the new bracket transforms into the Dirac bracket. Quantization is briefly discussed.

  4. The effects of two soft drinks on bond strength, bracket microleakage, and adhesive remnant on intact and sealed enamel.

    Science.gov (United States)

    Navarro, Raúl; Vicente, Ascensión; Ortiz, Antonio J; Bravo, Luis A

    2011-02-01

    The purpose of this study was to evaluate the effects of Coca-Cola and Schweppes Limón on bond strength, adhesive remnant, and microleakage beneath brackets. One hundred and twenty upper central incisor brackets were bonded to bovine incisors and divided into three groups: (1) Control, (2) Coca-Cola, and (3) Schweppes Limón. The teeth were submerged in the drinks three times a day for 15 minutes over a 15 day period. Shear bond strength (SBS) was measured with a universal testing machine, and adhesive remnant evaluated using image analysis equipment. Microleakage at the enamel-adhesive and adhesive-bracket interfaces was determined using methylene blue. One hundred and eight teeth were used for scanning electron microscopy to determine the effect of the drinks on intact and sealed enamel. SBS and adhesive remnant data were analysed using the Kruskal-Wallis test (P 0.05). Microleakage at the enamel-adhesive interface for groups 2 and 3 was significantly greater than for group 1 (P Coca-Cola and Schweppes Limón did not affect the SBS of brackets or the adhesive remnant.

  5. Influence of various surface-conditioning methods on the bond strength of metal brackets to ceramic surfaces

    NARCIS (Netherlands)

    Schmage, P; Nergiz, [No Value; Herrmann, W; Ozcan, M; Nergiz, Ibrahim; �zcan, Mutlu

    2003-01-01

    With the increase in adult orthodontic treatment comes the need to find a reliable method for bonding orthodontic brackets onto metal or ceramic crowns and fixed partial dentures. In this study, shear bond strength and surface roughness tests were used to examine the effect of 4 different surface co

  6. WELDING SEQUNCE KONSTRUKSI I-BRACKET PADA PEMBANGUNAN CREW BOAT PAN MARINE 10 DI PT JASA MARINA INDAH SEMARANG

    Directory of Open Access Journals (Sweden)

    Samuel Samuel

    2012-02-01

    Full Text Available This study aimed to determine the sequence of welding and the consequences that occur when the sequence of welding / welding sequence without a supported method of anticipating the occurrence of the pull of welding, the following ways to overcome it. All welding procedures have been implemented, but if not followed by the installation of equipment / tools that support the construction of certain sections, there will be pull welding of large, considering the construction of this very vulnerable Bracket I pull the weld. The position taken by the pull of welding, the center of I Bracket less to the left, less right, less rise, and less down. From the results of this study can be obtained data about the sequence of welding, welding method of the right to obtain maximum results for First Bracket construction welding jobs, find ways to overcome / cope in the event that lead to I pull welding Bracket less to the left, less right, less go up, less down, and get the alignment deviation according to the rule that conditioned. Results deviation below the alignment of the top 0.00 mm, bottom 0.15 mm, left 0.15 mm, right 0.17 mm.

  7. In vitro Effects of a Neutral Fluoride Agent on Shear Bond Strength and Microleakage of Orthodontic Brackets

    Directory of Open Access Journals (Sweden)

    Farzaneh Ahrari

    2014-06-01

    Full Text Available Introduction: This study aimed to evaluate the effect of pretreatment with a neutral fluoride agent on shear bond strength (SBS and microleakage of orthodontic brackets, and to investigate any significant relationship between SBS and microleakage. Methods: Forty intact premolars were selected and randomly divided into 2 groups. Group 1 served as the control, while group 2 underwent treatment with a 2% sodium fluoride (NaF gel, which was applied on the enamel surface for 4 minutes before etching. After bonding orthodontic brackets, the teeth were immersed for 12 hours in methylen blue dye, followed by mounting in acrylic resin. Shear bond strength was determined using an Instron Universal Testing Machine and the amount of microleakage and the adhesive remnant index (ARI were assessed under a stereomicroscope. Results: The mean SBS and microleakage beneath metal brackets were not significantly different among the control and NaF-treated groups (P>0.05. Furthermore, no significant correlation was found between SBS and microleakage (r=-0.04, P=0.796. The ARI scores revealed that in both groups, most of the adhesive remained on the enamel surface after debonding. Conclusions: It may be concluded that pretreatment of enamel with 2% NaF prior to the bonding procedure does not significantly affect microleakage and SBS of orthodontic brackets and thus, it can be recommended as a suitable approach to reduce the incidence of white spot lesions in orthodontically treated patients, especially those at high risk of caries formation.  

  8. Plaque accumulation and Streptococcus mutans levels around self-ligating bracket clips and elastomeric modules: A randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Dhaval Fadia

    2015-01-01

    Full Text Available Aim: To determine the effect of two different ligating systems that is, elastomeric modules and self-ligating (SL bracket systems (Smartclip - 3M Unitek with respect to harboring bacterial plaque in fixed orthodontic treatment. Objectives: To assess, evaluate, and compare the amount of plaque accumulation and Streptococcus mutans colonization around elastomeric ligation and SL clips in the smart clip appliance. Materials and Methods: A total of 111 orthodontic patients scheduled for fixed orthodontic treatments were selected for this split maxillary arch study. All the patients were bonded with smart-clip (3M Unitek SL brackets, and the wire was placed into the bracket slots, on the randomly selected hemi arch, elastomeric modules were placed for the study to be conducted. Microbial and periodontal plaque accumulation was recorded at 3-time intervals post ligation. Plaque index-by Silness and Loe, modified Quigely Hein index, bleeding on probing were evaluated, and biofilm was collected from the tooth surface after 30 days and placed in petri dishes containing Mitis Salivarius agar for bacterial culturing. Result: It was observed that the side where ligation was done with elastomeric modules accumulated more plaque and increase in S. mutans colony forming units as compared to the side without external ligation (P < 0.05. Conclusion: Reduced bacterial colonization and better plaque control was seen with SL orthodontic bracket appliance system as compared to conventional ligation method.

  9. CARIOSTATIC EFFECT AND FLUORIDE RELEASE FROM A VISIBLE LIGHT-CURING ADHESIVE FOR BONDING OF ORTHODONTIC BRACKETS

    NARCIS (Netherlands)

    OGAARD, B; REZKLEGA, F; RUBEN, J; ARENDS, J

    1992-01-01

    This study was designed to investigate the cariostatic potential in vivo of a visible light-curing adhesive for the bonding of orthodontic brackets. The fluoride release of the adhesive in water and saliva was also measured. Ten orthodontic patients with premolars to be extracted participated. One b

  10. Heat treatment following surface silanization in rebonded tribochemical silica-coated ceramic brackets: shear bond strength analysis

    Directory of Open Access Journals (Sweden)

    Emilia Adriane Silva

    2013-07-01

    Full Text Available OBJECTIVE: This study aimed to evaluate the effects of heat treatment on the tribochemical silica coating and silane surface conditioning and the bond strength of rebonded alumina monocrystalline brackets. MATERIAL AND METHODS: Sixty alumina monocrystalline brackets were randomly divided according to adhesive base surface treatments (n=20: Gc, no treatment (control; Gt, tribochemical silica coating + silane application; Gh, as per Gt + post-heat treatment (air flux at 100ºC for 60 s. Brackets were bonded to the enamel premolars surface with a light-polymerized resin and stored in distilled water at 37ºC for 100 days. Additionally, half the specimens of each group were thermocycled (6,000 cycles between 5-55ºC (TC. The specimens were submitted to the shear bond strength (SBS test using a universal testing machine (1 mm/min. Failure mode was assessed using optical and scanning electron microscopy (SEM, together with the surface roughness (Ra of the resin cement in the bracket using interference microscopy (IM. 2-way ANOVA and the Tukey test were used to compare the data (p>0.05. RESULTS: The strategies used to treat the bracket surface had an effect on the SBS results (p=0.0, but thermocycling did not (p=0.6974. Considering the SBS results (MPa, Gh-TC and Gc showed the highest values (27.59±6.4 and 27.18±2.9 and Gt-TC showed the lowest (8.45±6.7. For the Ra parameter, ANOVA revealed that the aging method had an effect (p=0.0157 but the surface treatments did not (p=0.458. For the thermocycled and non-thermocycled groups, Ra (µm was 0.69±0.16 and 1.12±0.52, respectively. The most frequent failure mode exhibited was mixed failure involving the enamel-resin-bracket interfaces. CONCLUSION: Regardless of the aging method, Gh promoted similar SBS results to Gc, suggesting that rebonded ceramic brackets are a more effective strategy.

  11. Esthetic dentistry for multiple gingival recession cases: Coronally advanced flap with bracket application

    Directory of Open Access Journals (Sweden)

    Minkle Gulati

    2016-01-01

    Full Text Available Treatment of gingival recession is essential to rectify the esthetic and functional deficiencies of the patient and to combat further periodontal destruction. However, treating multiple recession cases is quite challenging, and therefore requires constant modifications of the prevalent treatment strategies as per the severity of the condition. The objective of this case report was to evaluate the effectiveness of coronally advanced flap (CAF technique without vertical incisions using CAF brackets (CAF+B for treating a patient presenting with class II gingival recession defects in relation to maxillary anteriors. Complete root coverage was observed, and the results were consistent even after 6 months. The current case report demonstrates good outcomes of the CAF + B technique without the use of any additional soft tissue grafts or vertical incisions, therefore, endorsing the promising potential of the CAF + B technique in multiple gingival recession cases.

  12. Affine bracket algebra theory and algorithms and their applications in mechanical theorem proving

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper discusses two problems:one is some important theories and algorithms of affine bracket algebra;the other is about their applications in mechanical theorem proving.First we give some efficient algorithms including the boundary expanding algorithm which is a key feature in application.We analyze the characteristics of the boundary operator and this is the base for the implementation of the system.We also give some new theories or methods about the exact division,the representations and structure of affine geometry and so on.In practice,we implement the mechanical auto-proving system in Maple 10 based on the above algorithms and theories.Also we test about more than 100 examples and compare the results with the methods before.

  13. Affine bracket algebra theory and algorithms and their applications in mechanical theorem proving

    Institute of Scientific and Technical Information of China (English)

    Ning ZHANG; Hong-bo LI

    2007-01-01

    This paper discusses two problems: one is some important theories and algorithms of affine bracket algebra; the other is about their applications in mechanical theorem proving. First we give some efficient algorithms including the boundary expanding algorithm which is a key feature in application. We analyze the characteristics of the boundary operator and this is the base for the implementation of the system. We also give some new theories or methods about the exact division, the representations and structure of affine geometry and so on. In practice, we implement the mechanical auto-proving system in Maple 10 based on the above algorithms and theories. Also we test about more than 100 examples and compare the results with the methods before.

  14. Beatification: Flattening the Poisson Bracket for Two-Dimensional Fluid and Plasma Theories

    CERN Document Server

    Viscondi, Thiago F; Morrison, Philip J

    2016-01-01

    A perturbative method called beatification is presented for a class of two-dimensional fluid and plasma theories. The Hamiltonian systems considered, namely the Euler, Vlasov-Poisson, Hasegawa-Mima, and modified Hasegawa-Mima equations, are naturally described in terms of noncanonical variables. The beatification procedure amounts to finding the correct transformation that removes the explicit variable dependence from a noncanonical Poisson bracket and replaces it with a fixed dependence on a chosen state in phase space. As such, beatification is a major step toward casting the Hamiltonian system in its canonical form, thus enabling or facilitating the use of analytical and numerical techniques that require or favor a representation in terms of canonical, or beatified, Hamiltonian variables.

  15. The effect of APF-incorporated phosphoric acid etchant on shear bond strength of orthodontic brackets

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    Behnam Khosravanifard

    2011-01-01

    Full Text Available Background: The aim of this study was to evaluate the effect of adding acidulated phosphate fluoride (APF to phosphoric acid etchant on shear bond strength (SBS and adhesive remnant index (ARI of orthodontic brackets bonded to etched teeth. Methods: In this in vitro experimental study, 40 human premolars were etched with 37% phosphoric acid solution (Dentsply blended with 0, 25%, 50%, and 75% fractions of 1.23% APF (Dentsply. The brackets (Mini Dyna Lock, 3M were bonded (Transbond XT, 3M and were subjected to 96 hours of 37°C incubation and thermocycling procedures (2000 cycles, 5-55°C, dwell time = 30 s. Then, they were debonded at 1-mm crosshead speed to measure the SBS. The ARI was estimated at 10× magnification. The data were analyzed using the tests one-way analysis of variance (ANOVA, Tukey, chi-square, one-sample t-test, and Spearman correlation. Results: The SBS of the groups control, 25%, 50%, and 75% APF were 11.90±2.72, 8.01±3.13, 5.40±2.51, and 3.27±2.01 MPa, respectively. Mean ARI scores of these groups were 2.4 (control, 4.3, 4.7, and 4.8, respectively. According to the Tukey′s test, only the mean SBS of the second group (25% was not different from the control group (P=0.091. Conclusion: Adding about 20-25% of 1.23% APF to the phosphoric acid etchant might considerably reduce the amount of residual adhesive, without compromising the SBS.

  16. Influence of surface treatment on shear bond strength of orthodontic brackets

    Directory of Open Access Journals (Sweden)

    Ione Helena Vieira Portella Brunharo

    2013-06-01

    Full Text Available INTRODUCTION: The shear bond strength of orthodontic brackets bonded to micro-hybrid and micro-particulate resins under different surface treatment methods was assessed. METHODS: Two hundred and eighty test samples were divided into 28 groups (n = 10, where 140 specimens were filled with Durafill micro-particulate resin and 140 with Charisma composite. In 140 samples, a coupling agent (silane was applied. The surface treatment methods were: Phosphoric and hydrofluoric acid etching, sodium bicarbonate and aluminum oxide blasting, stone and burs. A Universal Instron Machine was used to apply an occlusal shear force directly to the resin composite bracket surface at a speed of 0.5 mm/min. The means were compared using analysis of variance and multivariate regression to assess the interaction between composites and surface treatment methods. RESULTS: Means and standard deviations for the groups were: Sodium bicarbonate jet 11.27±2.78; burs 9.26±3.01; stone 7.95±3.67; aluminum oxide blasting 7.04±3.21; phosphoric acid 5.82±1.90; hydrofluoric acid 4.54±2.87, and without treatment 2.75±1.49. An increase of 1.94 MPa in shear bond strength was seen in Charisma groups. Silane agent application reduced the Charisma shear bond strength by 0.68 Mpa, but increased Durafill means for bicarbonate blasting (0.83, burs (0.98 and stone drilling (0.46. CONCLUSION: The sodium bicarbonate blasting, burs and stone drilling methods produced adequate shear bond strength and may be suitable for clinical use. The Charisma micro hybrid resin composite showed higher shear bond means than Durafill micro particle composite.

  17. Timing considerations on the shear bond strength of orthodontic brackets after topical fluoride varnish applications

    Science.gov (United States)

    Cossellu, Gianguido; Lanteri, Valentina; Butera, Andrea; Laffi, Nicola; Merlini, Alberto; Farronato, Giampietro

    2017-01-01

    Objectives: To assess the best temporal association between the application of a fluoride varnish on enamel and bonding procedures. Materials and Methods: Eighty mandibular bovine incisors were used. Teeth were divided into 4 groups (20 per group); Groups 1–3 were treated with fluoride varnish (Fluor Protector, Ivoclar Vivadent, Schaan, Liechtenstein), and Group 4 served as control with no pretreatment. Tooth were stored in deionized water (37°C) and subjected to thermal cycling for 400 (Group 1), 800 (Group 2), and 2500 (Group 3) cycles corresponding, respectively, to 15, 30, and 90 days in order to simulate the three different timing of bracket bonding. Shear bond strength (SBS) was measured using an Instron Universal Testing machine. Tooth surfaces were examined under a stereomicroscope at 10× magnification to assess the amount of adhesive remnant index (ARI). One-way analysis of variance (ANOVA) and Tukey's honestly significant difference post-hoc test were used for the comparison of SBS values between groups (P < 0.05). The Chi-square test was used to examine differences among ARI scores. (P < 0.05). Results: One-way ANOVA and Tukey post-hoc test showed that the SBS of different groups were significantly different and was impacted by different timing of bonding (P < 0.05). The main differences were between the control group (17.02 ± 6.38 MPa) and Group 1 (6.93 ± 4.3 MPa). The ARI scores showed that there were no significant differences between the four tested groups. Conclusions: The SBS of the brackets bonded 15 days after the application of the fluoride was set back to an optimal value. PMID:28197397

  18. Enamel Surface Roughness after Debonding of Orthodontic Brackets and Various Clean-Up Techniques

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    Farzaneh Ahrari

    2013-01-01

    Full Text Available Objective: This study aimed to evaluate enamel roughness after adhesive removal using different burs and an Er:YAG laser.Materials and Methods: The buccal surfaces of forty human premolars were sealed by two layers of nail varnish, except for a circular area of 3 mm in diameter on the middle third. The enamel surfaces were initially subjected to profilometry analysis and four parameters of surface irregularity (Ra, Rq, Rt and Rz were recorded. Following bracket bonding and debonding, adhesive remnants were removed by tungsten carbide burs in low- or high- speed handpieces (group 1 and 2, respectively, an ultrafine diamond bur (group 3 or an Er:YAG laser (250 mJ, long pulse, 4 Hz (group 4, and surface roughness parameters were measured again. Then, the buccal surfaces were polished and the third profilometry measurements were performed.Results: The specimens that were cleaned with a low speed tungsten carbide bur showed no significant difference in surface irregularity between the different treatment stages (p>0.05. Surface roughness increased significantly after clean-up with the diamond bur and the Er:YAG laser (p<0.01. In comparison between groups, adhesive removal with tungsten carbide burs at slow- or high-speed handpieces produced the lowest, while enamel clean-up with the Er:YAG laser caused the highest values of roughness measurements (P<0.05.Conclusion: Under the study conditions, application of the ultrafine diamond bur or the Er:YAG laser caused irreversible enamel damage on tooth surface, and thus these methods could not be recommended for removing adhesive remnants after debonding of orthodontic brackets.

  19. Evaluation of the influence of dental bleaching with 35% hydrogen peroxide in orthodontic bracket shear bond strength

    Directory of Open Access Journals (Sweden)

    Marcus Vinicius Neiva Nunes do Rego

    2013-04-01

    Full Text Available OBJECTIVE: The purpose of this study was to evaluate, in vitro, the bond strength of brackets bonded to premolars previously subjected to bleaching with a 35% hydrogen peroxide. METHODS: Twenty one healthy premolars were selected and randomly divided into three groups (n = 7. Group I (G1 included teeth that were not submitted to bleaching. The enamel surfaces of Groups II (G2 and III (G3 were submitted to a bleaching process with 35% hydrogen peroxide (Whiteness HP Maxx. On Group II (G2, after bleaching, the teeth were stored for 24 hours in distilled water at 98.6 ºF, and then, premolar metallic brackets were bonded using Transbond XT (3M resin. Group III (G3 was submitted to the same procedure seven days after bleaching. After bonding, all teeth were stored in distilled water at 98.6 ºF for 24 hours. All groups were submitted to a traction test using an EMIC DL2000 universal testing machine at a speed of 0.5 mm/min. RESULTS AND CONCLUSION: The bracket resistance to debonding was compared between the groups by the Kruskal-Wallis nonparametric test (p < 0.05 and it was verified that the bleaching agent significantly reduced bracket adhesion when bonded 24 hours after bleaching. However, seven days after bleaching, there was no significant difference on the resistance to debonding among groups G1 (19,52 kgf and G3 (18,44 kgf, meaning that it is necessary to wait longer after bleaching to bond brackets.

  20. Evaluation of harmonic distortions using small scale computers; Avaliacao de distorcoes harmonicas utilizando-se computadores de pequeno porte

    Energy Technology Data Exchange (ETDEWEB)

    Paschoareli Junior, Dionizio

    1991-12-01

    The emergence more and more constant of non-linear loads in the power systems, with the consequent distortion in the voltage wave forms and of current, turns necessary complementary analyses in the planning of the systems, in way the if understands and to minimize the effects caused by the harmonic distortions. Among the methods used in this analysis are the computational programs that determine the flow of harmonic current and the voltages distorted in the buses. The objective of this work is the optimization of a program developed for large computers, turning possible its utilization in microcomputers. Besides, several models of components and two electric systems have its answers to the presence of multiple frequencies of the fundamental (harmonic frequency) evaluated and the results of the simulations will be presented. It also accomplishes simulations that make possible the visualization of the distortions in the voltage wave forms of the buses. Finally, the work offers a global and qualitative vision of this phenomenon that has been reason increasing preoccupation for mainly among the responsible for the quality of the supplied energy.

  1. Identificación de normalidad y anormalidad en la rodilla utilizando señales EMG

    OpenAIRE

    Herrera González, Marcelo; Martínez Herrera, Gustavo Adolfo; Aviles Sánchez, Oscar Fernando; Rodríguez Sotelo, José Luis

    2014-01-01

    En este trabajo se establecen algunos elementos importantes para estimar la relación entre la normalidad y la anormalidad en la rodilla humana, a través del análisis de las señales electromiográficas superficiales SEMG en cuatro músculos asociados a la articulación. Para ello, se debe construir una prueba básica estandarizada, para que a través de ella se puedan registrar las respuestas de los cuatro músculos medidos, y el conjunto de los ángulos de movimiento de la rodilla en flexión-extensi...

  2. Effect of fluoridated casein phospopeptide-amorphous-calcium phosphate complex, chlorhexidine fluoride mouthwash on shear bond strength of orthodontic brackets: A comparative in vitro study

    Directory of Open Access Journals (Sweden)

    C A Abdul Shahariyar

    2016-01-01

    Full Text Available Objective: The aim of the current study was to determine the effects of casein phosphopeptide amorphous calcium-phosphate (CPP-ACP complex, chlorhexidine fluoride mouthwash on shear bond strengths (SBSs of orthodontic brackets. Materials and Methods: About sixty extracted healthy human premolar teeth with intact buccal enamel were divided into two equal groups to which brackets were bonded using self-etching primers (SEPs and conventional means respectively. These were further equally divided into three subgroups - (1 control (2 CPP-ACP (3 chlorhexidine fluoride mouthwash. The SBSs were then measured using a universal testing machine. Results: SBS of the conventional group was significantly higher than the self-etching group. The intragroup differences were statistically insignificant. Conclusion: CPP-ACP, chlorhexidine fluoride mouthwash did not adversely affect SBS of orthodontic brackets irrespective of the method of conditioning. Brackets bonded with conventional technique showed greater bond strengths as compared to those bonded with SEP.

  3. Formulation of singular theories in a partial Hamiltonian formalism using a new bracket and multi-time dynamics

    CERN Document Server

    Duplij, Steven

    2013-01-01

    A formulation of singular classical theories (determined by degenerate Lagrangians) without constraints is presented. A partial Hamiltonian formalism in the phase space having an initially arbitrary number of momenta (which can be smaller than the number of velocities) is proposed. The equations of motion become first-order differential equations, and they coincide with those of multi-time dynamics, if a certain condition is imposed. In a singular theory, this condition is fulfilled in the case of the coincidence of the number of generalized momenta with the rank of the Hessian matrix. The noncanonical generalized velocities satisfy a system of linear algebraic equations, which allows an appropriate classification of singular theories (gauge and nongauge). A new antisymmetric bracket (similar to the Poisson bracket) is introduced, which describes the time evolution of physical quantities in a singular theory. The origin of constraints is shown to be a consequence of the (unneeded in our formulation) extension...

  4. Shear-bond-strength of orthodontic brackets to aged nano-hybrid composite-resin surfaces using different surface preparation.

    Science.gov (United States)

    Demirtas, Hatice Kubra; Akin, Mehmet; Ileri, Zehra; Basciftci, Faruk Ayhan

    2015-01-01

    The aim of this study was to evaluate the effects of different surface preparation methods on the shear bond strength (SBS) of orthodontic metal brackets to aged nano-hybrid resin composite surfaces in vitro. A total of 100 restorative composite resin discs, 6 mm in diameter and 3 mm thick, were obtained and treated with an ageing procedure. After ageing, the samples were randomly divided as follows according to surface preparation methods: (1)Control, (2)37% phosphoric acid gel, (3)Sandblasting, (4)Diamond bur, (5)Air-flow and 20 central incisor teeth were used for the control etched group. SBS test were applied on bonded metal brackets to all samples. SBS values and residual adhesives were evaluated. Analysis of variance showed a significant difference (phybrid composite resin surfaces.

  5. A combinatorial method for the vanishing of the Poisson brackets of an integrable Lotka-Volterra system

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Yoshiaki [Institute of Statistical Mathematics and the Graduate University for Advanced Studies, 4-6-7 Minami-Azabu Minatoku, Tokyo 106-8569 (Japan)], E-mail: itoh@ism.ac.jp

    2009-01-16

    The combinatorial method is useful to obtain conserved quantities for some nonlinear integrable systems, as an alternative to the Lax representation method. Here we extend the combinatorial method and introduce an elementary geometry to show the vanishing of the Poisson brackets of the Hamiltonian structure for a Lotka-Volterra system of competing species. We associate a set of points on a circle with a set of species of the Lotka-Volterra system, where the dominance relations between points are given by the dominance relations between the species. We associate each term of the conserved quantities with a subset of points on the circle, which simplifies to show the vanishing of the Poisson brackets.

  6. Assessment of clinical outcomes of Roth and MBT bracket prescription using the American Board of Orthodontics Objective Grading System

    Science.gov (United States)

    Jain, Mahesh; Varghese, Joseph; Mascarenhas, Rohan; Mogra, Subraya; Shetty, Siddarth; Dhakar, Nidhi

    2013-01-01

    Background: There is always a need to assess whether small changes in bracket prescription can lead to visually detectable differences in tooth positions. However, with little clinical evidence to show advantages of any of the popularly used bracket systems, orthodontists are forced to make clinical decisions with little scientific guidance. Aim: To compare the orthodontic cases finished with Roth and MBT prescription using American Board of Orthodontics-Objective Grading System (ABO-OGS). Settings and Design: Department of Orthodontics, Post-graduate dental college, retrospective cross-sectional study. Materials and Methods: Forty patients selected were divided into two groups of 20 patients each finished with straight wire appliance using Roth and MBT prescription, respectively. The examiner ability was assessed and calibrated by one of the ABO certified clinician to grade cases using the OGS. Statistical Analysis: Unpaired student t-test was used and P < 0.05 was accepted as significant. Results and Conclusions: MBT bracket group had a lower score of 2.60 points in buccolingual inclination and lower score of 1.10 points in occlusal contact category that was statistically significant when compared with Roth group. The difference in total ABO-OGS score was 2.65 points showing that the outcome for the MBT prescription was better than that of the Roth prescription, which is statistically significant, but with little or no clinical significance. It can be concluded that use of either one of the Roth and MBT bracket prescriptions have no impact to the overall clinical outcome and quality of treatment entirely depends on clinician judgment and experience. PMID:24124295

  7. Bond strength and durability of glass ionomer cements used as bonding agents in the placement of orthodontic brackets.

    Science.gov (United States)

    Klockowski, R; Davis, E L; Joynt, R B; Wieczkowski, G; MacDonald, A

    1989-07-01

    One potential risk of orthodontic treatment is the development of surface decalcification in association with use of brackets and bands. A bonding agent that could render tooth structure more resistant to the caries process clearly would reduce the negative iatrogenic outcomes of orthodontic therapy and thereby benefit the patient. Glass ionomer cement (GIC) bonds chemically to both enamel and dentin. In addition its high fluoride content makes enamel more resistant to caries. The purpose of this study was to evaluate the bond strength and durability of GIC when used as a bonding agent in the placement of orthodontic brackets. The materials tested were three GICs (Ketac-Fil, Ketac-Cem, and Chelon) and a standard bonding agent currently in widespread use (Rely-A-Bond). Brackets were attached to the facial surface of 96 premolar specimens and half the specimens for each bonding agent were thermocycled. Bond shear strength was determined with an Instron testing device by applying a load to the occlusal margin of each bracket to the point of failure. A two-way ANOVA indicated a significant bonding agent by thermocycling interaction (F = 4.78, p less than 0.01). Thermocycling decreased bond strength significantly for all materials, but had the greatest impact on Rely-A-Bond. However, Rely-A-Bond provided the strongest bond with and without thermocycling. Although bond strength for the standard orthodontic bonding agent deteriorates significantly under thermal stress, these results suggest that it is still greater than the bond strength provided by GIC materials.

  8. Assessment of clinical outcomes of Roth and MBT bracket prescription using the American Board of Orthodontics Objective Grading System

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    Mahesh Jain

    2013-01-01

    Full Text Available Background: There is always a need to assess whether small changes in bracket prescription can lead to visually detectable differences in tooth positions. However, with little clinical evidence to show advantages of any of the popularly used bracket systems, orthodontists are forced to make clinical decisions with little scientific guidance. Aim: To compare the orthodontic cases finished with Roth and MBT prescription using American Board of Orthodontics-Objective Grading System (ABO-OGS. Settings and Design: Department of Orthodontics, Post-graduate dental college, retrospective cross-sectional study. Materials and Methods: Forty patients selected were divided into two groups of 20 patients each finished with straight wire appliance using Roth and MBT prescription, respectively. The examiner ability was assessed and calibrated by one of the ABO certified clinician to grade cases using the OGS. Statistical Analysis: Unpaired student t-test was used and P < 0.05 was accepted as significant. Results and Conclusions: MBT bracket group had a lower score of 2.60 points in buccolingual inclination and lower score of 1.10 points in occlusal contact category that was statistically significant when compared with Roth group. The difference in total ABO-OGS score was 2.65 points showing that the outcome for the MBT prescription was better than that of the Roth prescription, which is statistically significant, but with little or no clinical significance. It can be concluded that use of either one of the Roth and MBT bracket prescriptions have no impact to the overall clinical outcome and quality of treatment entirely depends on clinician judgment and experience.

  9. Effect of laser-assisted bleaching with Nd:YAG and diode lasers on shear bond strength of orthodontic brackets.

    Science.gov (United States)

    Mirhashemi, Amirhossein; Emadian Razavi, Elham Sadat; Behboodi, Sara; Chiniforush, Nasim

    2015-12-01

    The aim of the present study was to assess the effect of laser-assisted bleaching with neodymium:yttrium-aluminum-garnet (Nd:YAG) and diode lasers on shear bond strength (SBS) of orthodontic brackets. One hundred and four extracted human premolars were randomly divided into four groups: group 1: No bleaching applied (control group); group 2: Teeth bleached with 40 % hydrogen peroxide; group 3: Teeth treated with 30 % hydrogen peroxide activated with Nd:YAG laser (1064 nm, 2.5 W, 25 Hz, pulse duration of 100 μs, 6 mm distance); and group 4: Teeth treated with 30 % hydrogen peroxide activated with diode laser (810 nm, 1 W, CW, 6 mm distance). Equal numbers of teeth in groups 2, 3, and 4 were bonded at start, 1 h, 24 h, and 1 week after bleaching. A universal testing machine measured the SBS of the samples 24 h after bonding. After bracket debonding, the amount of residual adhesive on the enamel surface was observed under a stereomicroscope to determine the adhesive remnant index (ARI) scores. The SBS in the unbleached group was significantly higher than that in the bleached groups bonded immediately and 1 h after laser-assisted bleaching (P laser-assisted bleaching, the SBS was found to be significantly lower than that in the control group. Significant differences in the ARI scores existed among groups as well. The SBS of brackets seems to increase quickly within an hour after laser-assisted bleaching and 24 h after conventional bleaching. Thus, this protocol can be recommended if it is necessary to bond the brackets on the same day of bleaching.

  10. Shear Bond Strength of Al2O3 Sandblasted Y-TZP Ceramic to the Orthodontic Metal Bracket

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    Seon Mi Byeon

    2017-02-01

    Full Text Available As the proportion of adult orthodontic treatment increases, mainly for aesthetic reasons, orthodontic brackets are directly attached to yttria-stabilized tetragonal zirconia polycrystal (Y-TZP restorations. This, study analyzed the shear bond strength (SBS between various surface treated Y-TZP and orthodontic metal brackets. The Y-TZP specimens were conditioned by 110 μm Al2O3 sandblasting, or sandblasting followed by coating with one of the primers (silane, MDP, or an MDP-containing silane primer. After surface treatment, the orthodontic metal bracket was bonded to the specimen using a resin cement, and then 24 h storage in water and thermal cycling (5000 cycles, 5–55 °C, SBS was measured. Surface roughness was analyzed for surface morphology, and X-ray photoelectron spectroscopy (XPS was employed for characterization of the chemical bond between the Y-TZP and the MDP-based primers (MDP, MDP containing silane primer. It was found that after surface treatment, the surface roughness of all groups increased. The groups treated with 110 μm Al2O3 sandblasting and MDP, or MDP-containing silane primer showed the highest SBS values, at 11.92 ± 1.51 MPa and 13.36 ± 2.31 MPa, respectively. The SBS values significantly decreased in all the groups after thermal cycling. Results from XPS analysis demonstrated the presence of chemical bonds between Y-TZP and MDP. Thus, the application of MDP-based primers after Al2O3 sandblasting enhances the resin bond strength between Y-TZP and the orthodontic metal bracket. However, bonding durability of all the surface-treated groups decreased after thermal cycling.

  11. A comparison between two lingual orthodontic brackets in terms of speech performance and patients' acceptance in correcting Class II, Division 1 malocclusion: a randomized controlled trial

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    Samiha Haj-Younis

    Full Text Available ABSTRACT Objective: To compare speech performance and levels of oral impairment between two types of lingual brackets. Methods: A parallel-group randomized controlled trial was carried out on patients with Class II, Division 1 malocclusion treated at the University of Hama School of Dentistry in Hama, Syria. A total of 46 participants (mean age: 22.3 ± 2.3 years with maxillary dentoalveolar protrusion were randomly distributed into two groups with 23 patients each (1:1 allocation ratio. Either STb (Ormco or 7th Generation (Ormco lingual brackets were applied. Fricative sound/s/ spectrograms were analyzed directly before intervention (T0, one week following premolar extraction prior to bracket placement (T1, within 24 hours of bracket bonding (T2, one month after (T3, and three months after (T4 bracket placement. Patients′ acceptance was assessed by means of standardized questionnaires. Results: After bracket placement, significant deterioration in articulation was recorded at all assessment times in the 7th Generation group, and up to T3 in the STb group. Significant intergroup differences were detected at T2 and T3. No statistically significant differences were found between the two groups in reported tongue irritation levels, whereas chewing difficulty was significantly higher in the 7th Generation group one month after bracket placement. Conclusions: 7th Generation brackets have more interaction with sound production than STb ones. Although patients in both groups complained of some degree of oral impairment, STb appliances appeared to be more comfortable than the 7th Generation ones, particularly within the first month of treatment.

  12. Effect of Saliva Contamination on Shear Bond Strength of Orthodontic Brackets When Using a Self-Etch Primer

    Institute of Scientific and Technical Information of China (English)

    MAO Jing; QI Juan

    2005-01-01

    The effect of saliva contamination on the shear bond strength of orthodontic brackets, at various stages of the bonding procedure using a new self-etch primer was studied. The samples were divided into 4 groups according to 4 different enamel surface conditions: Group A: dry; Group B: saliva contamination before priming; Group C: saliva contamination after priming, and Group D: saliva contamination before and after priming. Stainless steel brackets were bonded in each test group with a light-cured composite resin (TransbondXT 3M). The shear bond strength was determined in the first 30 min after bonding. The analysis of variance indicated that the shear bond strengths of the 4 groups were significantly different (F= 11.89, P<0.05). Tukey HSD tests indicated that contamination both before and after the application of the acid-etch primer resulted in a significantly lower (=4.6± 1.7 MPa) shear bond strength than either the control group (= 8.8±1.9 MPa) or the groups where contamination occurred either before ( = 7.9± 2.0 MPa) or after (=6.9±1.5 MPa) the application of the primer. It was concluded that the new acid-etch primer could maintain adequate shear bond strength if contamination occurred either before or after the application of the primer. On the other hand, contamination both before and after the application of the primer could significantly reduce the shear bond strength of orthodontic brackets.

  13. Comparative in vitro study of the shear bond strength of brackets bonded with restorative and orthodontic resins

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    Hassan Isber

    2011-02-01

    Full Text Available The aim of this study was to evaluate the shear bond strength of brackets bonded with different restorative systems and compare it with that afforded by an established orthodontic bonding system. Seventy human bicuspids were used, divided into five different groups with 14 teeth each. Whereas a specific orthodontic bonding resin (TransbondTM XT was used in the control group, the restorative systems Charisma, Tetric Ceram, TPH Spectrum and Z100 were used in the other four groups. Seven days after bonding the brackets to the samples, shear forces were applied under pressure in a universal testing machine. The data collected was evaluated using the ANOVA test and, when a difference was identified, the Tukey test was applied. A 5% level of significance was adopted. The mean results of the shear bond strength tests were as follows: Group 1 (Charisma, 14.98 MPa; Group 2 (Tetric Ceram, 15.16 MPa; Group 3 (TPH, 17.70 MPa; Group 4 (Z100, 13.91 MPa; and Group 5 or control group (TransbondTM XT, 17.15 MPa. No statistically significant difference was found among the groups. It was concluded that all tested resins have sufficient bond strength to be recommended for bonding orthodontic brackets.

  14. The Corbel Bracket Art in Zhang Clan Garden%张家花园斗拱艺术

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    张家花园斗拱构造区别于大式建筑的斗拱形态,斗、昂、拱等构件造型不同于传统的构件造型和做法,斗拱整体不承重,并采用雕刻、彩绘的构造手法装饰以吉祥瑞兽、植物花卉、法器静物,以中国传统文化为载体,体现吉祥和谐、富贵平安、安居乐业的建筑装饰文化寓意,呈现出其建筑视觉语言的独特性。%The structures of the corbel bracket in Zhang Clan Garden is different from the forms of the corbel bracket in Great-style architecture. Its corbel, rising and arch constructs are different from traditional ones in forms and making. The integration of corbel bracket isn’t weight-bearing and decorates with wood carvings and exquisite paintings showing auspicious animals, plants, religion objects and still objects, all of which reflects auspicious, harmonious, rich, safe and happy implications in architecture decoration by taking Chinese traditional cultures as the carrier and shows a unique visual language of Chinese architecture.

  15. Assessment of Bond Strength between Metal Brackets and Non-Glazed Ceramic in Different Surface Treatment Methods

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    I. Harririan

    2010-06-01

    Full Text Available Objective: The aim of this study was to evaluate the bond strength between metal brackets and non-glazed ceramic with three different surface treatment methods.Materials and Methods: Forty-two non-glazed ceramic disks were assigned into three groups. Group I and II specimens were etched with 9.5% hydrofluoric acid. Subsequently in group I, silane and adhesive were applied and in group II, bonding agent was used only.In group III, specimens were treated with 35% phosphoric acid and then silane and adhesive were applied. Brackets were bonded with light-cured composites. The specimens were stored in water in room temperature for 24 hours and then thermocycled 500 times between 5°C and 55°C.Results: The difference of tensile bond strength between groups I and III was not significant(P=0.999. However, the tensile bond strength of group II was significantly lower than groups I, and III (P<0.001. The adhesive remnant index scores between the threegroups had statistically significant differences (P<0.001.Conclusion: With the application of scotch bond multi-purpose plus adhesive, we can use phosphoric acid instead of hydrofluoric acid for bonding brackets to non-glazed ceramic restorations.

  16. Effectiveness of an Er:YAG laser in etching the enamel surface for orthodontic bracket retention.

    Science.gov (United States)

    Kim, Jung-Ho; Kwon, Oh-Won; Kim, Hyung-Il; Kwon, Yong Hoon

    2005-12-01

    The purpose of this study was to test the effectiveness of an Er:YAG laser in etching the enamel surface for orthodontic treatment. Bovine incisors were either acid-etched or laser-treated. An orthodontic bracket was attached on each treated surface using one-step dentin adhesive and self-curing resin. Tensile bond strength was then evaluated. In addition, the surface morphology of specimens treated with phosphoric acid/laser and self-etching primer, as well as the cross-section of enamel-primer-resin interfaces, were observed. One-Up Bond F-treated specimens after Er:YAG laser ablation showed statistically similar tensile bond strength (9.9 +/- 1.3 MPa) to that of phosphoric acid-etched specimens (11.8 +/- 1.7 MPa). Surface roughness and thickness of the enamel-primer-resin interfaces did not much affect the tensile bond strength of the tested specimens. In conclusion, Er:YAG laser ablation achieved clinically acceptable level of tensile bond strength when used with One-Up Bond F.

  17. 轿车备胎支架的设计%Design of Car Spare Tire Bracket

    Institute of Scientific and Technical Information of China (English)

    张旭忠; 王苗苗

    2016-01-01

    Tires are very important components in cars ,every car is equipped with a spare tire ,due to the structure of car itself ,the spare tire is mostly placed in the trunk ,and the space is narrow ,so it is difficult for a driver to replace a tire independently .In this paper ,a spare tire bracket installed in the trunk is designed ,which uses a gas spring ,to make the replacement of spare tire more easier .%轮胎是汽车使用过程中非常重要的安全部件,每辆轿车都安装有备胎,但由于轿车自身结构的限制,现有轿车备胎大都安放在后备箱中,空间狭小,更换时比较费力。因此,设计了一种轿车备胎安装支架,采用气弹簧支架,安装布置在后备箱中,此设计结构简单,同时能够减少更换备胎时的难度。

  18. Improving long time behavior of Poisson bracket mapping equation: a non-Hamiltonian approach.

    Science.gov (United States)

    Kim, Hyun Woo; Rhee, Young Min

    2014-05-14

    Understanding nonadiabatic dynamics in complex systems is a challenging subject. A series of semiclassical approaches have been proposed to tackle the problem in various settings. The Poisson bracket mapping equation (PBME) utilizes a partial Wigner transform and a mapping representation for its formulation, and has been developed to describe nonadiabatic processes in an efficient manner. Operationally, it is expressed as a set of Hamilton's equations of motion, similar to more conventional classical molecular dynamics. However, this original Hamiltonian PBME sometimes suffers from a large deviation in accuracy especially in the long time limit. Here, we propose a non-Hamiltonian variant of PBME to improve its behavior especially in that limit. As a benchmark, we simulate spin-boson and photosynthetic model systems and find that it consistently outperforms the original PBME and its Ehrenfest style variant. We explain the source of this improvement by decomposing the components of the mapping Hamiltonian and by assessing the energy flow between the system and the bath. We discuss strengths and weaknesses of our scheme with a viewpoint of offering future prospects.

  19. Transversal changes in dental arches from non-extraction treatment with self ligating brackets

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    Liliana Avila Maltagliati

    2013-06-01

    Full Text Available OBJECTIVE: The present study aimed at analyzing, with the use of dental casts, the transverse changes of the upper and lower dental arches, after non-extraction orthodontic treatment, with self-ligating brackets. METHODS: The sample comprised 29 patients, all presenting Class I malocclusion with upper and lower crowding of at least 4 mm and treated only with a fixed appliance, without stripping, extraction or distalization. The dental casts were obtained before and after leveling with 0.019 x 0.025-in stainless steel archwires. CONCLUSION: The results indicated that the majority of transverse changes occurred at the premolar areas, both the first and the second, as well as on the upper and lower dental arches. The intercanine distance increased 0.75 mm, on average, in the upper arch and 1.96 mm in the lower arch. The molars also demonstrated a tendency towards an increase in their transverse dimension, however, at a lower intensity comparing to premolars. All measurements presented statistically significant differences with the exception of the maxillary second molars.

  20. Influence of various surface-conditioning methods on the bond strength of metal brackets to ceramic surfaces.

    Science.gov (United States)

    Schmage, Petra; Nergiz, Ibrahim; Herrmann, Wolfram; Ozcan, Mutlu

    2003-05-01

    With the increase in adult orthodontic treatment comes the need to find a reliable method for bonding orthodontic brackets onto metal or ceramic crowns and fixed partial dentures. In this study, shear bond strength and surface roughness tests were used to examine the effect of 4 different surface conditioning methods: fine diamond bur, sandblasting, 5% hydrofluoric acid, and silica coating for bonding metal brackets to ceramic surfaces of feldspathic porcelain. Sandblasting and hydrofluoric acid were further tested after silane application. A total of 120 ceramic disc samples were produced, and 50 were used for surface roughness measurements. The glazed ceramic surfaces were used as controls. Metal brackets were bonded to the ceramic substrates with a self-curing composite. The samples were stored in 0.9% NaCl solution for 24 hours and then thermocycled (5000 times, 5 degrees C to 55 degrees C, 30 seconds). Shear bond tests were performed with a universal testing device, and the results were statistically analyzed. Chemical surface conditioning with either hydrofluoric acid (4.3 microm) or silicatization (4.4 microm) resulted in significantly lower surface roughness than mechanical conditioning (9.3 microm, diamond bur; 9.7 microm, sandblasting) (P <.001). The surface roughness values reflect the mean peak-and-valley distances. The bond strengths of the brackets bonded to the ceramic surfaces treated by hydrofluoric acid with and without silane (12.2 and 14.7 MPa, respectively), silicatization (14.9 MPa), and sandblasting with silane (15.8 MPa) were significantly higher (P <.001) than those treated by mechanical roughening with fine diamond burs (1.6 MPa) or sandblasting (2.8 MPa). The highest bond strength values were obtained with sandblasting and silicatization with silane or hydrofluoric acid without silane; these fulfilled the required threshold. The use of silane after hydrofluoric acid etching did not increase the bond strength. Diamond roughening and

  1. Evaluation of ionic degradation and slot corrosion of metallic brackets by the action of different dentifrices

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    Gustavo Antônio Martins Brandão

    2013-02-01

    Full Text Available OBJECTIVE: To evaluate the in vitro ionic degradation and slot base corrosion of metallic brackets subjected to brushing with dentifrices, through analysis of chemical composition by Energy Dispersive Spectroscopy (EDS and qualitative analysis by Scanning Electron Microscopy (SEM. METHODS: Thirty eight brackets were selected and randomly divided into four experimental groups (n = 7. Two groups (n = 5 worked as positive and negative controls. Simulated orthodontic braces were assembled using 0.019 x 0.025-in stainless steel wires and elastomeric rings. The groups were divided according to surface treatment: G1 (Máxima Proteção Anticáries®; G2 (Total 12®; G3 (Sensitive®; G4 (Branqueador®; Positive control (artificial saliva and Negative control (no treatment. Twenty eight brushing cycles were performed and evaluations were made before (T0 and after (T1 experiment. RESULTS: The Wilcoxon test showed no difference in ionic concentrations of titanium (Ti, chromium (Cr, iron (Fe and nickel (Ni between groups. G2 presented significant reduction (p OBJETIVO: avaliar in vitro a degradação iônica e corrosão do fundo do slot de braquetes metálicos submetidos à escovação com dentifrícios, realizando análises da composição química por Espectroscopia de Energia Dispersiva (EDS e qualitativa por Microscopia Eletrônica de Varredura (MEV. MÉTODOS: foram selecionados 38 braquetes divididos aleatoriamente em quatro grupos experimentais (n = 7. Dois grupos (n = 5 funcionaram como controles positivo e negativo. Aparelhos ortodônticos simulados foram confeccionados com fios de aço inoxidável 0,019" x 0,025" e anéis elastoméricos. Os grupos foram divididos de acordo com o tratamento de superfície: G1 (Máxima Proteção Anticáries®; G2 (Total 12®; G3 (Sensitive®; G4 (Branqueador®; Controle Positivo (saliva artificial e Controle Negativo (sem tratamento. Foram realizados 28 ciclos de escovação e avaliações antes (T0 e após (T1 o

  2. Efficiency of different protocols for enamel clean-up after bracket debonding: an in vitro study

    Science.gov (United States)

    Sigilião, Lara Carvalho Freitas; Marquezan, Mariana; Elias, Carlos Nelson; Ruellas, Antônio Carlos; Sant'Anna, Eduardo Franzotti

    2015-01-01

    Objective: This study aimed to assess the efficiency of six protocols for cleaning-up tooth enamel after bracket debonding. Methods: A total of 60 premolars were divided into six groups, according to the tools used for clean-up: 12-blade bur at low speed (G12L), 12-blade bur at high speed (G12H), 30-blade bur at low speed (G30L), DU10CO ORTHO polisher (GDU), Renew System (GR) and Diagloss polisher (GD). Mean roughness (Ra) and mean roughness depth (Rz) of enamel surface were analyzed with a profilometer. Paired t-test was used to assess Ra and Rz before and after enamel clean-up. ANOVA/Tukey tests were used for intergroup comparison. The duration of removal procedures was recorded. The association between time and variation in enamel roughness (∆Ra, ∆Rz) were evaluated by Pearson's correlation test. Enamel topography was assessed by scanning electron microscopy (SEM). Results: In Groups G12L and G12H, original enamel roughness did not change significantly. In Groups G30L, GDU, GR and GD, a smoother surface (p < 0.05) was found after clean-up. In Groups G30L and GD, the protocols used were more time-consuming than those used in the other groups. Negative and moderate correlation was observed between time and (∆Ra, ∆Rz); Ra and (∆Ra, ∆Rz); Rz (r = - 0.445, r = - 0.475, p < 0.01). Conclusion: All enamel clean-up protocols were efficient because they did not result in increased surface roughness. The longer the time spent performing the protocol, the lower the surface roughness. PMID:26560825

  3. Efficiency of different protocols for enamel clean-up after bracket debonding: an in vitro study

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    Lara Carvalho Freitas Sigilião

    2015-10-01

    Full Text Available Objective: This study aimed to assess the efficiency of six protocols for cleaning-up tooth enamel after bracket debonding.Methods:A total of 60 premolars were divided into six groups, according to the tools used for clean-up: 12-blade bur at low speed (G12L, 12-blade bur at high speed (G12H, 30-blade bur at low speed (G30L, DU10CO ORTHO polisher (GDU, Renew System (GR and Diagloss polisher (GD. Mean roughness (Ra and mean roughness depth (Rz of enamel surface were analyzed with a profilometer. Paired t-test was used to assess Ra and Rz before and after enamel clean-up. ANOVA/Tukey tests were used for intergroup comparison. The duration of removal procedures was recorded. The association between time and variation in enamel roughness (∆Ra, ∆Rz were evaluated by Pearson's correlation test. Enamel topography was assessed by scanning electron microscopy (SEM.Results:In Groups G12L and G12H, original enamel roughness did not change significantly. In Groups G30L, GDU, GR and GD, a smoother surface (p < 0.05 was found after clean-up. In Groups G30L and GD, the protocols used were more time-consuming than those used in the other groups. Negative and moderate correlation was observed between time and (∆Ra, ∆Rz; Ra and (∆Ra, ∆Rz; Rz (r = - 0.445, r = - 0.475, p < 0.01.Conclusion:All enamel clean-up protocols were efficient because they did not result in increased surface roughness. The longer the time spent performing the protocol, the lower the surface roughness.

  4. Volcanic rifts bracketing volcanoes: an analogue answer to an old unsolved problem

    Science.gov (United States)

    Mussetti, Giulio; van Wyk de Vries, Benjamin; Corti, Giacomo; Hagos, Miruts

    2015-04-01

    It has been observed in Central America that many volcanoes have volcanic alignments and faults at their east and west feet. A quick look at many rifts indicates that this also occurs elsewhere. While this feature has been noted for at least 30 years, no explanation has ever really been convincingly put forward. During analogue experiments on rifting volcanoes we have mixed the presence of a volcanic edifice with an underlying intrusive complex. The models use a rubber sheet that is extended and provides a broad area of extension (in contrast to many moving plate models that have one localised velocity discontinuity). This well suits the situation in many rifts and diffuse strike-slip zones (i.e. Central America and the East African Rift). We have noted the formation of localised extension bracketing the volcano, the location of which depends on the position of the analogue intrusion. Thus, we think we have found the answer to this long standing puzzle. We propose that diffuse extension of a volcano and intrusive complex generates two zones of faulting at the edge of the intrusion along the axis of greatest extensional strain. These serve to create surface faulting and preferential pathways for dykes. This positioning may also create craters aligned along the axis of extension, which is another notable feature of volcanoes in Central America. Paired volcanoes and volcanic uplifts in the Danakil region of Ethiopia may also be a consequence of such a process and lead us to draw some new preliminary cross sections of the Erta Ale volcanic range.

  5. In vitro corrosion of metallic orthodontic brackets: influence of artificial saliva with and without fluorides

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    Mônica Pereira Saporeti

    2012-12-01

    Full Text Available OBJECTIVE: This in vitro study verified the resistance to corrosion of metallic brackets, evaluating the superficial aspects in scanning electron microscopy (SEM and the residual components. METHODS: The sample consisted of 17 sets of brackets of four different metallic alloys: Titanium, Cobalt-Chromium, Stainless steel with low nickel concentration and with titanium nitride coating (NiTi. Twelve sets were submitted to corrosion by immersion in 50 ml of artificial saliva (pH 6.5 and four in saliva (pH 6.5 containing fluoride (2 g/l, all at a temperature of 37 ºC and analyzed after 7, 9 and 11 weeks. One was kept as control set. The analysis consisted in qualitative evaluation of the corrosion by the images obtained on the SEM, in semi-quantitative evaluation of chemical composition of the surface residue by SEM-EDS and the amount of ions released in saliva on evaluation of atomic absorption spectrophotometry. RESULTS: The results showed that the pure titanium brackets and the ones with low nickel concentration were superior regarding resistance to corrosion. The cobalt-chromium alloy showed the greatest corrosion. In the presence of fluoride, it was observed greater variation in all alloys, especially in the ones of NiTi coated steel and the ones of cobalt-chromium. CONCLUSION: Although observed corrosion on the SEM, the spectrophotometry showed low ions release in the artificial saliva, however, the presence of fluoride negatively affected the corrosion resistance.OBJETIVO: este estudo in vitro verificou a resistência à corrosão de braquetes metálicos, avaliando-se os aspectos superficiais em microscopia eletrônica de varredura (MEV e os componentes residuais formados. MÉTODOS: a amostra consistiu de 17 conjuntos de braquetes de quatro diferentes ligas metálicas: titânio, cobalto-cromo, aço inoxidável com baixa concentração de níquel e com cobertura de nitreto de titânio (TiN. Doze conjuntos foram submetidos à corrosão por

  6. The effect of a light-emitting diode on shear bond strength of ceramic brackets bonded to feldspathic porcelain with different curing times.

    Science.gov (United States)

    Elekdag-Turk, Selma; Sarac, Y Sinasi; Turk, Tamer; Sarac, Duygu

    2007-06-01

    The aim of this study was to evaluate different curing times of a light-emitting diode (LED) unit on shear bond strength (SBS) of ceramic brackets bonded to feldspathic porcelain. Ceramic brackets were bonded with a light-cured adhesive to 96 feldspathic porcelain facets. Air-borne particle abrasion was performed using 25 mum aluminium trioxide (Al(2)O(3)) with an air abrasion device from a distance of approximately 10 mm at a pressure of 2.5 bars for 4 seconds, then the porcelain surfaces were etched with 9.6 per cent hydrofluoric acid for 2 minutes. After surface preparation of the porcelain specimens, silane was applied. In groups 1 and 2, the adhesive was cured with a quartz-tungsten-halogen (QTH) unit for 10 and 20 seconds, respectively. The LED was used in the standard mode for 3, 5, and 10 seconds for groups 3, 4, and 5, respectively. For the other three groups, the LED was used in the fast mode for 3, 5, and 10 seconds, respectively. The SBS of the brackets was measured on a universal testing machine. The adhesive remnant index (ARI) scores, damage to the porcelain, and fracture of the ceramic bracket bases were determined. No significant differences were observed for SBS between the eight groups (P=0.087). There was no significant difference between the groups' ARI scores, porcelain damage, and bracket base fracture (P=0.340, P=0.985, and P=0.340, respectively). There was a greater frequency of ARI scores of 0 for all groups. Fifty per cent of the porcelain facets displayed damage. Nineteen ceramic bracket base fractures were observed. No significant difference was found for the SBS of the groups with QTH and LED units and curing times. It is reliable to use LED with a 3-second curing time since it provided adequate bond strength for ceramic brackets bonded to porcelain surfaces.

  7. Evaluation of frictional resistance and surface characteristics after immersion of orthodontic brackets and wire in different chemical solutions: A comparative in vitrostudy

    Directory of Open Access Journals (Sweden)

    Kavitha Nanjundan

    2016-01-01

    Full Text Available Aim: To evaluate the changes of static and kinetic frictional forces between the brackets and wires following exposure to a soft drink, acidic food ingredient, and acidulated fluoride prophylactic agents. Materials and Methods: Two types of Roth prescription mandibular incisor brackets were used: 3M Unitek Victory stainless steel (SS brackets (n = 40 and Transcend 6000 polycrystalline alumina (PCA brackets (n = 40 as well as eighty 0.019 × 0.025" dimension ortho technology SS wires of 50 mm length each. Subsequently, brackets tied with SS wires divided into eight subgroups (n = 10 and were immersed in vinegar (pH = 3.5 ± 0.5, Pepsi ® (pH = 2.46, Colgate Phos-Flur mouth rinse (pH = 5.1, and artificial saliva (control group pH = 7 for 24 h. Changes in surface morphology under scanning electron microscope ×1000, surface roughness (Ra with surface profilometer (single bracket and single wire from each subgroup, and frictional resistance using universal testing machine were evaluated. Results: Highest mean (standard deviation static frictional force of 2.65 (0.25 N was recorded in Pepsi ® followed by 2.57 (0.25 N, 2.40 (0.22 N, and 2.36 (0.17 N for Vinegar, Colgate Phos-Flur mouth rinse, and artificial saliva groups, respectively. In a similar order, lesser mean kinetic frictional forces obtained. PCA brackets revealed more surface deterioration and higher frictional force values than SS brackets. A significant positive correlation was observed between frictional forces and bracket slot roughness (r = 0.861 and 0.802, respectively, for static and kinetic frictional forces, p < 0.001 for both and wire roughness (r = 0.243 and 0.242, respectively, for static and kinetic frictional forces, p < 0.05 for both. Conclusions: Findings may have long-term implications when acidic food substances are used during fixed orthodontic treatment. Further, in vivo studies are required to analyze the clinical effect of acidic mediums in the oral environment during

  8. Effects of surface-conditioning methods on shear bond strength of brackets bonded to different all-ceramic materials.

    Science.gov (United States)

    Saraç, Y Şinasi; Külünk, Tolga; Elekdağ-Türk, Selma; Saraç, Duygu; Türk, Tamer

    2011-12-01

    The aims of this study were to investigate the effects of two surface-conditioning methods on the shear bond strength (SBS) of metal brackets bonded to three different all-ceramic materials, and to evaluate the mode of failure after debonding. Twenty feldspathic, 20 fluoro-apatite, and 20 leucite-reinforced ceramic specimens were examined following two surface-conditioning methods: air-particle abrasion (APA) with 25 μm Al(2)O(3) and silica coating with 30 μm Al(2)O(3) particles modified by silica. After silane application, metal brackets were bonded with light cure composite and then stored in distilled water for 1 week and thermocycled (×1000 at 5-55°C for 30 seconds). The SBS of the brackets was measured on a universal testing machine. The ceramic surfaces were examined with a stereomicroscope to determine the amount of composite resin remaining using the adhesive remnant index. Two-way analysis of variance, Tukey's multiple comparison test, and Weibull analysis were used for evaluation of SBS. The lowest SBS was with APA for the fluoro-apatite ceramic (11.82 MPa), which was not significantly different from APA for the feldspathic ceramic (13.58 MPa). The SBS for the fluoro-apatite ceramic was significantly lower than that of leucite-reinforced ceramic with APA (14.82 MPa). The highest SBS value was obtained with silica coating of the leucite-reinforced ceramic (24.17 MPa), but this was not significantly different from the SBS for feldspathic and fluoro-apatite ceramic (23.51 and 22.18 MPa, respectively). The SBS values with silica coating showed significant differences from those of APA. For all samples, the adhesive failures were between the ceramic and composite resin. No ceramic fractures or cracks were observed. Chairside tribochemical silica coating significantly increased the mean bond strength values.

  9. Effect of Fast Curing Lights, Argon Laser, and Plasma Arc on Bond Strengths of Orthodontic Brackets: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    M. Hashem-Hoseini

    2008-12-01

    Full Text Available Objective: Nowadays light-cured composites are used widely by orthodontists to bond brackets. As these composites require 20-40 seconds time per tooth to be light cured, more chair-time in needed compared to self-cured composites. In recent years, the argon laser and plasma arc lights have been introduced in dentistry to reduce this curing time. The purpose of this study was to compare bond strength of brackets bonded with the argon la-ser and plasma arc light with those bonded with the conventional halogen light.Materials and Methods: Fifty-one intact human premolars were randomly divided into three groups of 17 teeth each. Stainless steel twin premolar brackets (018- in Dyna lock, 3M Unitek were bonded to the teeth using one of these curing devices in each group: the halogen unit (Coltolux 75, Switzerland, the argon laser unit (Bo-5, Iran , and the plasma arc unit (Remecure 15, Belgium. The orthodontic adhesive was the same in the three groups (Transbond XT, 3M Unitek. After thermal cycling, the diametral tensilebond strength of specimens was measured using a debonding plier in a Zwick Universal Testing machine (Z/100, Germany.Results: The mean bond strengths was 17.344 MPa (SD=4.567 for halogen 19.172 MPa(SD=6.328 for laser and 19.322 MPa (SD=4.036 for plasma arc groups. No statistically significant difference existed in the mean bond strengths among three groups.Conclusion: Argon laser lights, significantly reducing the curing time of orthodonticbrackets without affecting bond strength, have the potential to be considered as advanta-geous alternatives to conventional halogen light.

  10. Efectos de las fuerzas ortodóncicas, producidas por brackets autoligantes activos y pasivos, sobre el cemento radicular.

    OpenAIRE

    Pavani Carillo, Jorge José

    2016-01-01

    Introducción: El objetivo de este trabajo, de carácter clínico experimental, fue observar in vitro, mediante la utilización de distintos tipos de microscopios y del estudio microanalítico, los posibles cambios estructurales y químicos del cemento radicular, producidos por el efecto de las fuerzas ortodóncicas generadas al emplear brackets autoligantes activos y pasivos, luego del período de alineación, nivelación y expresión inicial de torque del tratamiento ortodóncico. Materiales ...

  11. 滑槽支架成形模设计%Design of Forming Die for the Sliding Chute Bracket

    Institute of Scientific and Technical Information of China (English)

    杨智红

    2012-01-01

    以滑槽支架为例,进行了工艺分析、模具结构解析。介绍了模具设计要点,并更多的考虑了模具结构的可调整性、稳定性。%Taking the sliding chute bracket as an example, the forming process and die structure were analyzed. Introduced the design points of forming die, considered adjusted and stability of die structure.

  12. Finite element and experimental analysis of pinion bracket-assembly of three gorges project ship lift

    Institute of Scientific and Technical Information of China (English)

    石端伟; 汪勇波; 彭惠; 赵铁柱; 程术潇

    2015-01-01

    The pinion bracket-assembly (PBA) is a major part of three gorges project (TGP) ship lift drive system. The static strength, fatigue strength and stress distribution of hinge pin of PBA were analyzed by ANSYS, and the structure of PBA was optimized. The results show that after the optimization, the maximum comprehensive stress is 259.59 MPa, the maximum fatigue cumulative damage of weld joints is 0.94 and the maximum vertical deformation of hinge pin is 0.14 mm. The elastic deformation, hydropneumatic spring cylinder (HSC) load response and the vibration characteristics of PBA were studied by the bearing test when PBA bore the load caused by different water level errors. The results indicate that when the water level of ship chamber ranges from 3.4 m to 3.6 m, the vertical elastic deformation of the pinion shaft is between−8.58 and 10.50 mm. When upward outage-load(1580 kN) is imposed by the test-rack, the vertical elastic deformation of the pinion shaft is 13.42 and 14.07 mm and HSC load response is 795.80−800.80 kN. In the process of imposing load on the pinion by the test-rack, the maximum vibration amplitude and acceleration of PBA internal components are 0.37° and 2.67 rad/s2, respectively;the maximum impact on the pin caused by vibration is 19.89 kN; the pinion shaft vertical displacement and HSC load response do not fluctuate. There is a great difference between the frequency of meshing force of the pinion and the rack (1.06 Hz) and first-order natural frequency of PBA(8.41 Hz), thus PBA will not resonate. From all above, PBA meets the static strength and fatigue strength requirements. The vibration of PBA internal components has no effect on the vertical displacement of the pinion shaft, HSC load response and smooth operation of PBA. There is a liner relationship in the ratio of 2:1 between the thrust imposed by the test-rack and HSC load, thus HSC can limit the load imposed on the pinion.

  13. Vitalidade pulpar em dentes portadores de brackets ortodônticos: apresentação de uma técnica = Pulp vitality test on teeth having orthodontics brackets: technique presentation

    Directory of Open Access Journals (Sweden)

    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

  14. Comparison of two kinds of brackets on torque control%两种托槽对转矩控制影响的比较研究

    Institute of Scientific and Technical Information of China (English)

    田军; 柳忠豪; 刘利苹; 武传君; 张丁

    2009-01-01

    目的 研究在同一牙弓中牙齿相互作用条件下,0.56mm×0.71 mm(0.022英寸×0.028英寸)国产奥杰全程式托槽与日本OPA-K金属托槽在转矩控制方面是否有差异.方法 通过Typodont水浴实验,模拟临床矫治过程,测量结束弓丝为0.48 mm×0.64 mm(0.019英寸× 0.025英寸)SS方丝时使用两种品牌托槽的上颌5⊥5的唇舌向倾斜度,并通过数学编程计算转化为上颌5⊥5的转矩余隙角ψ,对其绝对值进行配对t检验.结果 结束弓丝为0.48 mm ×0.64 mm(0.019英寸×0.025英寸)SS方丝时,OPA-K金属托槽的转矩余隙角ψ的绝对值为(4.834±2.846)°,奥杰全程式金属托槽的转矩余隙角ψ的绝对值为(4.469±3.213)°,两种托槽间的差异无统计学意义(P=0.309).结论 0.56 mm×0.71 mm(0.022英寸× 0.028英寸)的OPA-K金属托槽和奥杰全程式托槽在转矩控制方面无差异,临床上使用这两种托槽均可达到满意的转矩控制.%Objective To compare the effect of two kinds of brackets (OPA-K and ORJ metal brackets)on torque con-trol when teeth are interacted in the same arch. Methods After the upper arch was aligned and leveled in Typodont study, the inclinations of upper teeth 5⊥5 were measured when 0.56 mm × 0.71 mm OPA-K metal brackets and 0.56 mm × 0.71 mm ORJ brackets were filled with 0.48 mm × 0.64 mm SS. The inclinatons of each tooth were transformed to the absolute values of the torque play angle ψ by computing program, and paired-t test was used. Results The two kinds of brackets had no statistical significance on torque control when the brackets were filled with 0.48 mm × 0.64 mm SS;the absolute values of the angle ψ in 0.56 mm × 0.71 mm OPA-K metal brackets and 0.56 mm × 0.71 mm ORJ metal brackets were 4.834°±2.846° and 4.469°±3.213° respectively. There was no statistical significance between the two kinds of brackets. Conclusion There is no difference between 0.56 mm × 0.71 mm OPA-K metal bracket and 0.56 mm × 0.71 mm ORJ

  15. Model analasis on front bracket of semi-trailer suspension%半挂车悬架前支架的模态分析

    Institute of Scientific and Technical Information of China (English)

    丁华; 商高高; 李辉

    2011-01-01

    A finite element model for the front bracket of semi-trailer suspension is biut by using the three-dime nsional graphics CATIA software ,and the stifftness and strength characteristics of front bracket is simulated with the model,and its stress and deformation under the load is got;Through the model analysis,the dynamic parameters of the front bracket of semi-trailer suspension are obtained%应用三维软件CATIA建立了半挂车悬架前支架的有限元模型,对前支架的刚度和强度特性进行了仿真模拟,获得了前支架的应力应变分布情况;找到了前支架应力集中的部位,在此基础上求得了前支架的固有振动特性.

  16. Normal torque of the buccal surface of mandibular teeth and its relationship with bracket positioning: a study in normal occlusion.

    Science.gov (United States)

    Mestriner, Marcelo Antonio; Enoki, Carla; Mucha, José Nelson

    2006-01-01

    This study evaluated the degree of buccolingual inclination of mandibular tooth crowns relative to torque. For such purpose, mandibular and maxillary stone casts from 31 Caucasian Brazilian adults with normal occlusion, pleasant facial aspect and no history of previous orthodontic treatment were examined. A custom device was developed for measuring the degree of inclination (torque) of bracket slots of orthodontic appliances relative to the occlusion plane, at three bonding height: standard (center of clinical crown), occlusal (0.5 mm occlusally from standard) and cervical (0.5 mm cervically from standard). Except for the mandibular incisors, which presented a small difference in torque from one another (lingual root torque for central incisors and buccal root torque for lateral incisors), the remaining average values are close to those found in the literature. Due to the convexity of the buccal surface, the 1-mm vertical shift of the brackets from occlusal to cervical affected the values corresponding to the normal torque, in approximately 2 degrees in central and lateral incisors, 3 degrees in canines and 8 degrees in premolars and molars.

  17. Dynamics Analysis of Underwater Vehicle Motor Bracket%某水下航行器电机支架的动力学分析

    Institute of Scientific and Technical Information of China (English)

    刘晓明; 迟毅林; 伍星; 柳小勤

    2012-01-01

    振动噪声是水下航行器的重要指标,水下航行器的电机支架是振动传递的关键,因此以某水下航行器电机支架为研究对象,采用CAD软件Solid Edge建模,用有限元软件ANSYS Workbench对其进行动力学分析,包括模态分析和谐响应分析.通过有限元计算得到电机支架的固有频率和对应的振型,进而计算出结构的频率响应曲线,分析峰值频率对应的应力与变形,找出电机机架的共振频率,最后评估水下航行器电机支架的动态性能,为支架进一步结构设计提供了理论依据.%Noise and vibration is an important indicator for underwater vehicle, motor bracket of underwater vehicle is the key to the vibration transmission, this paper takes motor bracket of some underwater vehicle for research object,model building by the CAD software Solid Edge,dynamic analysis \\which including modal analysis and harmonic response analysis by finite element software ANSYS Workbench. Through finite element analysis, the volun^e got natural frequency and mode shapes of the motor bracket, calculated response curve of the structure under different frequencies, analyzed the stress and deformation at the peak frequency as well as found the resonant frequency of the motor bracket,finally evaluated the dynamic performance of the underwater vehicle motor bracket. The result provides a theoretical basis of further structural design for the bracket.

  18. 一种尖牙控轴直丝托槽的结构设计%Structural design of the canine axis adjustable straight wire bracket

    Institute of Scientific and Technical Information of China (English)

    潘杰; 赵君; 姜宁; 陈骊

    2015-01-01

    Objective To design a new type of bracket: canine axis adjustable straight wire bracket, which is used to treat malocclusion, and analyse its structure and principle in this article. Methods The structure of axis adjustable bracket is consist of two sets of diagonal bracket wings, which can take a rotation around the axis between each other and be adapted to various archwire ligation methods. Results A new type of axis adjustable bracket was designed to have two sets of rotary diagonal bracket wings, and doctors can change the height and width of bracket slot by different ligation ways and choose different orthodontic correction systems. Conclusion When using the canine axis adjustable straight wire brackets, we can choose different orthodontic correction systems by different ligation ways.%目的:设计一种用于错畸形的正畸治疗的新型托槽——尖牙控轴直丝托槽,对其结构设计和应用原理进行探讨分析。方法定性设计矫治器的结构,托槽两个对角旋转翼与另两个对角翼可以通过旋转轴发生转动,能灵活选择放入弓丝前不锈钢丝结扎托槽与放入弓丝后弹性结扎托槽等结扎方式。结果设计出一种尖牙正畸控轴直丝托槽,其特征是两对角托槽翼与另两个对角翼可以通过旋转轴发生转动,从而改变托槽槽沟的高度及宽度。结论使用尖牙控轴托槽时,可以通过结扎尖牙控轴托槽的合龈翼来选择采取不同的矫治系统。

  19. A comparative study of shear bond strength of orthodontic bracket after acid-etched and Er:YAG treatment on enamel surface

    Science.gov (United States)

    Leão, Juliana C.; Mota, Cláudia C. B. O.; Cassimiro-silva, Patricia F.; Gomes, Anderson S. L.

    2016-02-01

    This study aimed to evaluate the shear bond strength (SBS) of teeth prepared for orthodontic bracket bonding with 37% phosphoric acid and Er:YAG laser. Forty bovine incisors were divided into two groups. In Group I, the teeth were conditioned with 37% phosphoric acid and brackets were bonded with Transbond XT; in Group II, the teeth were irradiated with Er:YAG and bonding with Transbond XT. After SBS test, the adhesive remnant index was determined. Adhesion to dental hard tissues after Er:YAG laser etching was inferior to that obtained after acid etching but exceeded what is believed to be clinically sufficient strength, and therefore can be used in patients.

  20. 3M自锁托槽与直丝弓托槽在正畸治疗过程中应用的比较%3M self-locking bracket versus straight wire bracket during orthodontic treatment

    Institute of Scientific and Technical Information of China (English)

    李庆祝

    2015-01-01

    BACKGROUND:Self-locking brackets changed the traditional ligation mode and obviously elevated the sliding mechanism of the teeth and the effect of its spreading during orthodontic treatment, and effectively decreased friction force. OBJECTIVE:To explore the differences of the application of 3M self-locking bracket and traditional straight wire bracket during orthodontic treatment. METHODS:A total of 796 patients receiving orthodontic correction of mild and moderate misaligned teeth, including 398 males and 400 females, at the age of 11-19 years old. 398 patients received 3M SmartClipTM self-ligating bracket braces as observation group. The remaining 398 patients received MBT straight wire appliance. The width of molars, intercanine width, superior anterior tooth convexity and correction were compared between the two groups. RESULTS AND CONCLUSION:The width of premolars and superior anterior tooth convexity were significantly better after correction than that before correction in both groups (P<0.05). Moreover, the correction outcomes were significantly better in the observation group than in the control group (P<0.05). No significant difference in the width of first molar and intercanine width was detected before and after treatment in either group, as wel as between the two groups. Aligned dentition time and the total therapeutic duration were shorter in the observation group than in the control group (P<0.05). These findings indicate that compared with the traditional MBT straight wire bracket braces, expansion arch effect of the 3M SmartClipTM self-ligating bracket braces is obvious;clinical treatment can reduce the rate of extraction cases, and shorten the course of correction.%背景:自锁托槽矫治器的出现改变了传统的结扎方式,显著提升了矫治过程中牙齿的滑动机制及扩弓效果,有效降低了摩擦力。目的:探讨3M自锁托槽和传统直丝弓托槽在正畸治疗过程中的应用效果差异。方法:纳入轻

  1. Streptococcus mutans counts in plaque adjacent to orthodontic brackets bonded with resin-modified glass ionomer cement or resin-based composite

    Directory of Open Access Journals (Sweden)

    Solange Machado Mota

    2008-03-01

    Full Text Available This study investigated the number of Streptococcus mutans CFU (colony forming units in the saliva and plaque adjacent to orthodontic brackets bonded with a glass ionomer cement - GIC (Fuji Ortho or a resin-based composite - RC (Concise. Twenty male and female patients, aged 12 to 20 years, participated in the study. Saliva was collected before and after placement of appliances. Plaque was collected from areas adjacent to brackets and saliva was again collected on the 15th, 30th, and 45th day after placement. On the 30th day, 0.4% stannous fluoride gel was applied for 4 minutes. No significant modification in the number of Streptococcus mutans CFU in saliva was observed after placement of the fixed orthodontic appliances. On the 15th day, the percentage of Streptococcus mutans CFU in plaque was statistically lower in sites adjacent to GIC-bonded brackets (mean = 0.365 than in those adjacent to RC-bonded brackets (mean = 0.935. No evidence was found of a contribution of GIC to the reduction of CFU in plaque after the 15th day. Topical application of stannous fluoride gel on the 30th day reduced the number of CFU in saliva, but not in plaque. This study suggests that the antimicrobial activity of GIC occurs only in the initial phase and is not responsible for a long-term anticariogenic property.

  2. Plaque retention by self-ligating vs elastomeric orthodontic brackets: quantitative comparison of oral bacteria and detection with adenosine triphosphate-driven bioluminescence.

    NARCIS (Netherlands)

    Pellegrini, P.; Sauerwein, R.W.; Finlayson, T.; McLeod, J.; Covell, D.A.; Maier, T.; Machida, C.A.

    2009-01-01

    INTRODUCTION: Enamel decalcification is a common problem in orthodontics. The objectives of this randomized clinical study were to enumerate and compare plaque bacteria surrounding 2 bracket types, self-ligating (SL) vs elastomeric ligating (E), and to determine whether adenosine triphosphate (ATP)-

  3. Influence of CO2 (10.6 μm) and Nd:YAG laser irradiation on the prevention of enamel caries around orthodontic brackets.

    Science.gov (United States)

    Seino, Priscila Yumi; Freitas, Patrícia Moreira; Marques, Márcia Martins; de Souza Almeida, Fernanda Campos; Botta, Sérgio Brossi; Moreira, Maria Stella Nunes Araújo

    2015-02-01

    One possible undesirable consequence of orthodontic therapy is the development of incipient caries lesions of enamel around brackets. The aim of this study was to compare the effects of CO2 (λ = 10.6 μm) and Nd:YAG (λ = 1,064 nm) lasers associated or not with topical fluoride application on the prevention of caries lesions around brackets. Brackets were bonded to the enamel of 65 premolars. The experimental groups (n = 13) were: G1--application of 1.23% acidulated fluoride phosphate gel (AFP, control); G2--Nd:YAG laser irradiation (0.6 W, 84.9 J/cm(2), 10 Hz, 110 μs, contact mode); G3--Nd:YAG laser irradiation associated with AFP; G4--CO2 laser irradiation (0.5 W, 28.6 J/cm(2), 50 Hz, 5 μs, and 10 mm focal distance); and G5--CO2 laser irradiation associated with AFP. Quantitative light-induced fluorescence was used to assess enamel demineralization. The data were statistically compared (α = 5%). The highest demineralization occurred in the Nd:YAG laser group (G2, 26.15% ± 1.94). The demineralization of all other groups was similar to that of the control group. In conclusion, CO2 laser alone was able to control enamel demineralization around brackets at the same level as that obtained with topical fluoride application.

  4. Perception of discomfort during initial orthodontic tooth alignment using a self-ligating or conventional bracket system: a randomized clinical trial.

    Science.gov (United States)

    Scott, Paul; Sherriff, Martyn; Dibiase, Andrew T; Cobourne, Martyn T

    2008-06-01

    The aim of this study was to compare the degree of discomfort experienced during the period of initial orthodontic tooth movement using Damon3 self-ligating and Synthesis conventional ligating pre-adjusted bracket systems. Sixty-two subjects were recruited from two centres (32 males and 30 females; mean age 16 years, 3 months) with lower incisor irregularity between 5 and 12 mm and a prescribed extraction pattern, including lower first premolar teeth. These subjects were randomly allocated for treatment with either bracket system. Fully ligated Damon3 0.014-inch Cu NiTi archwires were used for initial alignment in both groups. Following archwire insertion, the subjects were given a prepared discomfort diary to complete over the first week, recording discomfort by means of a 100 mm visual analogue scale at 4 hours, 24 hours, 3 days, and 1 week. The subjects also noted any self-prescribed analgesics that were taken during the period of observation. Data were analysed using repeated measures analysis of variance. There were no statistically significant differences in perceived discomfort levels between the two appliances; discomfort did not differ at the first time point and did not develop differently across subsequent measurement times. Overall, this investigation found no evidence to suggest that Damon3 self-ligating brackets are associated with less discomfort than conventional pre-adjusted brackets during initial tooth alignment, regardless of age or gender.

  5. Reliability analysis of a Shift Platform Bracket Based on ANSYS%基于ANSYS的移动平台支架可靠性分析

    Institute of Scientific and Technical Information of China (English)

    朱亚超; 程欣; 丁善婷; 何涛

    2012-01-01

    The ANSYS finite-element analysis software was adopted to analyze the displacement and deformation of solar energy testing shift platform bracket under weight of automatic tracker and solar panel during testing process.Form variable data was then compared with actual data.The results indicate that: adding one set of lock device and back-up unit at the end of shift platform bracket and reinforcing connection between platform bracket and back-up leg can improve safety and reliability of the whole platform bracket and testing device.%采用ANSYS有限元分析软件,对太阳能测试移动平台支架在测试过程中承受自动追踪器和太阳能集热板重量后发生的位移形变进行分析,比较计算形变量数据与实际数据,得出在移动平台支架尾部增加一组锁死装置和支撑装置,以加强移动平台与支撑腿连结,可提高整个平台支架和测试设备的安全性与可靠性的结论.

  6. High-dynamic-range microscope imaging based on exposure bracketing in full-field optical coherence tomography.

    Science.gov (United States)

    Leong-Hoi, Audrey; Montgomery, Paul C; Serio, Bruno; Twardowski, Patrice; Uhring, Wilfried

    2016-04-01

    By applying the proposed high-dynamic-range (HDR) technique based on exposure bracketing, we demonstrate a meaningful reduction in the spatial noise in image frames acquired with a CCD camera so as to improve the fringe contrast in full-field optical coherence tomography (FF-OCT). This new signal processing method thus allows improved probing within transparent or semitransparent samples. The proposed method is demonstrated on 3 μm thick transparent polymer films of Mylar, which, due to their transparency, produce low contrast fringe patterns in white-light interference microscopy. High-resolution tomographic analysis is performed using the technique. After performing appropriate signal processing, resulting XZ sections are observed. Submicrometer-sized defects can be lost in the noise that is present in the CCD images. With the proposed method, we show that by increasing the signal-to-noise ratio of the images, submicrometer-sized defect structures can thus be detected.

  7. 支架复合弯曲模的设计%Design of Composite Bending Die for the Bracket

    Institute of Scientific and Technical Information of China (English)

    文建平

    2012-01-01

    针对支架零件的结构特点与生产批量要求,对该支架零件进行了冲压成形工艺分析与计算,确定了合理的工艺方案,设计了一次弯曲成形复合模,介绍了模具结构特点及工作过程。经生产实践,该模具结构合理,支架零件质量好。%The structural characteristics of the bracket parts and production volume requirements,the product stamping process analysis and calculation to determine a reasonable process plan,design a bending and forming of the composite die,the die structure characteristics and working principle,production practices showed,the die structure is reasonable,and with good product quality.

  8. Modeling of Roller Bracket on SolidWorks%基于SolidWorks的上托辊架三维建模

    Institute of Scientific and Technical Information of China (English)

    邵娜

    2015-01-01

    介绍一种利用SolidWorks软件中的焊件设计模块对带式输送机托辊架进行建模的方法,该方法操作简单、快捷。通过对上托辊架的三维建模以及虚拟装配,可以很直观地检查出设计中的错误,提高设计效率。%Introduces a method of roller bracket model of belt conveyor by using weldment design module of SolidWorks software, the method is simple and fast. Through the roller frame 3D modeling and virtual assembly, can be very intuitive to check out the design errors and improve design efficiency.

  9. A single-aliquot OSL protocol using bracketing regenerative doses to accurately determine equivalent doses in quartz

    CERN Document Server

    Folz, E

    1999-01-01

    In most cases, sediments show inherent heterogeneity in their luminescence behaviours and bleaching histories, and identical aliquots are not available: single-aliquot determination of the equivalent dose (ED) is then the approach of choice and the advantages of using regenerative protocols are outlined. Experiments on five laboratory bleached and dosed quartz samples, following the protocol described by Murray and Roberts (1998. Measurement of the equivalent dose in quartz using a regenerative-dose single aliquot protocol. Radiation Measurements 27, 171-184), showed the hazards of using a single regeneration dose: a 10% variation in the regenerative dose yielded some equivalent dose estimates that differed from the expected value by more than 5%. A protocol is proposed that allows the use of different regenerative doses to bracket the estimated equivalent dose. The measured ED is found to be in excellent agreement with the known value when the main regeneration dose is within 10% of the true equivalent dose.

  10. Shape Optimization Design of the Automobile Seat Belt Bracket%汽车安全带固定支架的形貌优化设计

    Institute of Scientific and Technical Information of China (English)

    高志彬; 汪攀; 赵锴

    2016-01-01

    The finite element model of an automobile seat belt bracket was built by the HyperWorks software. The bracket of original design was carried out CAE analysis. The results show that the largest stress of the bracket of original design is 347MPa, which exceed 340MPa ,the yield strength of the material. So it need optimization. Using shape optimization technology determined the best distribution of reinforcement and optimize the design. The results showed that the maximum deformation of optimized automobile safety belts bracket was reduced by 36.7%, stress decreased by 17.6%, total strain energy decreased by 32.9%. The mechanical properties of car safety belts bracket was improved, which achieve the optimal effect.%利用hyperworks软件建立了某汽车安全带固定支架的有限元模型,对原设计支架进行了CAE分析,结果表明原设计的支架最大应力为347MPa,超过材料屈服强度340Mpa,需优化设计。用形貌优化技术确定了加强筋的最佳分布方案,进行了优化设计。结果表明,优化后的汽车安全带固定支架最大变形量减少36.7%,最大应力降低17.6%,总体应变能减小32.9%。改善了汽车安全带固定支架的力学性能,达到了优化效果。

  11. Comparison of the Load-Deflection Characteristics of Aesthetic and Conventional Super Elastic Ni-Ti Orthodontic Arch Wires in Conventional and Metal-Insert Ceramic Brackets

    Science.gov (United States)

    Aghili, Hosseinagha; Yassaei, Soghra; Joshan, Neda

    2016-01-01

    Introduction Coated arch wires and ceramic brackets have been introduced to improve aesthetics during orthodontic treatment. Aim The aim of this study was to determine the effects of coating on the physical properties of aesthetic orthodontic wires. Material and Methods Five round wires (0.016 inch) were obtained from each of three brands: conventional uncoated super elastic Nickel Titanium (Ni-Ti) (Rematitian Lite; Dentaurum, Ispringen, Germany), HUBIT (Teflon Coated, Korea), G&H (Epoxy Coated, Greenwood, Indiana, USA) which belonged to maxillary arch. Two types of standard ceramic brackets (conventional and metal-insert type, Ortho Technology, Tampa, Florida, USA) with the slot size of 0.022×0.028 inches were used. A simulation device was fabricated to resemble a model of human dental arch and each of the specimen was tested in three-point bending test. The test was conducted in the buccolingual plane with crosshead speed of 1mm/minute pressure from metal pole. Each sample was loaded until a deflection of 3.0 mm was produced. The mean values of maximum loading force, unloading force and clinical plateau length were recorded. One-way ANOVA and Tukey tests were used at p<0.05. Results Uncoated Ni-Ti arch wire showed higher mean values of maximum loading and unloading force than that of coated aesthetic wires similar to ceramic brackets while G&H wire and metal-insert ceramic brackets presented the lowest values. The longest clinical plateau length was observed in G&H wires and metal-insert ceramic bracket. Conclusion The coating processes for HUBIT (Teflon Coated, Korea), G&H (Epoxy Coated, Greenwood, Indiana, USA) wires might influence bending behaviour which can cause decrease in loading and unloading force. PMID:28208994

  12. Establishment of computer aided bracket positioning system%计算机辅助托槽定位系统的建立

    Institute of Scientific and Technical Information of China (English)

    兰泽栋; 周丽淑

    2014-01-01

    目的 建立基于3D扫描、打印架构下的计算机辅助托槽定位系统(computer aided bracket placement system,CABPS).方法 通过3D扫描获取3D数字化牙颌模型,利用正畸计算机辅助设计(orthodontics computer aided design,Ortho CAD)技术对数字化模型进行牙齿分离,按照正常咬合六项标准进行牙齿排列;基于临床冠中心法和托槽槽沟平直化原则做计算机辅助托槽定位,计算机对已附带托槽定位标尺的牙齿进行原态模型复位,3D打印,压制托槽定位模板,在模拟(牙合)架上进行托槽间接粘接后模拟矫治,验证矫治效果.结果 在3D扫描、打印架构下,基于Ortho CAD技术建立了CABPS.结论 CABPS可提高托槽定位精度,实现了矫治效果可预期、可视.%Objective The aim of this study was to present a computer aided orthodontic bracket positioning system,which was based on 3D scanning,3D printing and orthodontic computer aided design (Ortho CAD).Methods Digital dental model was obtained by 3D scanning.By the aid of Ortho CAD,digital teeth were separated from virtual model and realigned based on the rule of Andrew's Six Keys.The positions of orthodontic brackets were calculated on individual digital tooth in the center of clinical crown with the diriction according to slot straighthening principle.The virtual teeth were then aligned back to their original position,and created a new dental model with bracket positioning marker by 3D printer.Based on the new dental model,an individual stent was produced for indirect bonding.To test the accuracy of the system,a simulated orthodontic treatment was performed through Typodont procedures.Results the Computer Aided Bracket Positioning System (CABPS) was established based on Ortho CAD,3D scanning and 3D printing.Conclusions CABPS could increase the accuracy of bracket placement and predictability of orthodontic treatment.

  13. Delta Force托槽矫治错(牙合)畸形%Orthodontic Treatment with Delta Force Brackets

    Institute of Scientific and Technical Information of China (English)

    武玉海; 陈建民; 兰泽栋

    2013-01-01

    目的:探讨低摩擦力矫治器(Delta Force矫治器)矫治错(牙合)畸形特点.方法:选择25名患者(其中安氏Ⅰ类9名、安氏Ⅱ类11名、安氏Ⅲ类5名),使用Delta Force矫治器进行正畸治疗.矫治中选择不同类型的结扎方式以减小矫治器系统的摩擦阻力.结果:患者矫治结束后均获得正常覆(牙合)覆盖和后牙尖窝咬(牙合)关系,疗程平均26.2个月.托槽脱落率为6.9%.结论:临床应用Delta Force矫治器可根据牙齿移动和控制的需要选择不同的结扎方式,既有利于牙齿的移动,又可对牙齿移动进行有效控制.%Objective:To investigate the efficiency and effectiveness of orthodontic treatment with a low friction appliance (Delta Force appliance).Methods:Twenty-five patients were selected to participate into this study.Delta Force brackets were used during their orthodontic treatment.Different ligation methods were selected in the treatment to reduce the systematic friction.Results:All of the orthodontic treatments were completed.Normal overbite and overjet and good relationship of posterior teeth were obtained.The average treatment time was 26.2 months.The bracket loss rate was 6.9%.Conclusion:According to the tooth movement and control,different ligation methods may be used in orthodontic treatment with Delta Force appliance in order to enhance the tooth movement and obtain the effective tooth control.

  14. Shear bond strength of metal brackets to feldspathic porcelain treated by Nd:YAG laser and hydrofluoric acid.

    Science.gov (United States)

    Hosseini, Mohammad Hashem; Sobouti, Farhad; Etemadi, Ardavan; Chiniforush, Nasim; Shariati, Mahsa

    2015-02-01

    Adult orthodontic treatment requires bonding orthodontic attachment to dental restorations. Ceramics are commonly used as esthetic restorative materials for the crowns and bridges. The present study evaluated the shear bond strength of metal orthodontic brackets to the feldspathic porcelain surfaces following conditioning by different powers of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser and hydrofluoric acid as a conventional method. Seventy-two glazed porcelain samples were prepared and randomly attributed to six equal groups of 12. In the conventional hydrofluoric (HF) group, the specimens were etched by 9.6% hydrofluoric acid for 4 min. In laser groups, samples were conditioned by 0.75-, 1-, 1.25-, 1.5-, and 2-W Nd:YAG laser for 10 s. Metal brackets were bonded to porcelain samples and after being stored in distilled water for 24 h, they were subjected to thermocycling for 500 cycles. The debonding was carried out by a Zwick testing machine. The data were statistically analyzed by ANOVA and Tamhane multiple comparisons tests. The mean ± SD of the shear bond strength in the laser group 0.75, 1, 1.25, 1.5, and 2 W and HF group was 2.2 ± 0.9, 4.2 ± 1.1, 4.9 ± 2.4, 7 ± 1.7, 9.6 ± 2.7, and 9.4 ± 2.5, respectively. Together with the increased power of laser, the mean shear bond strength was increased continuously and no significant differences were found between the HF group and the laser groups with power of 1.5 or 2 W. Also, there was no significant difference between all test groups in ARI scores. There was no significant difference between bond strength of laser groups with power of 1.5 and 2 W and HF-etched group. So, Nd:YAG laser with appropriate parameters can be used as an alternative method for porcelain etching.

  15. Comparative evaluation of the shear bond strength of metal brackets bonded to porcelain using different porcelain surface treatments

    Directory of Open Access Journals (Sweden)

    Eslami Amirabadi GH

    2011-02-01

    Full Text Available "nBackground and Aims: The aim of this in vitro study was to compare shear bond strength of metal brackets bonded to dental porcelain on the basis of presence or absence of silane, type of acid [hydrofluoric acid (HF or phosphoric acid (H3PO4] and roughness of porcelain surface (glazed or deglazed within mouth-like environment."nMaterials and Methods: Eighty glazed ceramic disks were randomly divided into 8 groups of 10 disks: group 1 [HF+silane], group 2 [deglazed+HF+silane], group 3 [HF], group 4 [deglazed+HF], group 5 [H3PO4+silane], group 6 [deglazed+H3PO4+silane], group 7 [H3PO4], group 8 [deglazed+H3PO4]. Then the brackets were bonded and thermocycled. After that, shear bond strength test was done using the Zwick device and the type of bond failure was determined under stereomicroscope at 4X magnification. 3-way ANOVA and Kruskal-Wallis were used for statistical analyses."nResults: The shear bond strength for the test groups were as follows: group (1:13.05±7.7 MPa , group (2:25.16±10.66 MPa, group (3:6.7±5.86 MPa, group (4:15.39±8.97 MPa, group (5:12.76±7.91 MPa, group (6:13.57±7.85 MPa, group (7:0.54±0.67 MPa, group (8: 9.34±6.52 MPa. The type of bond failure in all groups was adhesive failure except for group 2. No significant difference in the interaction between (glazed or deglazed, (presence or absence of silane, and type of acid was found (P>0.05."nConclusion: Under the conditions of this study, the best clinical method was the use of 37% phosphoric acid and silane that resulted in the optimal clinical strength and adhesive bond failure.

  16. A new self-curing resin-modified glass-ionomer cement for the direct bonding of orthodontic brackets in vivo.

    Science.gov (United States)

    Fricker, J P

    1998-04-01

    A new self-curing (chemically cured) resin-modified glass-ionomer cement, Fuji Ortho (GC International), is based on the technology of hybrid glass-ionomer restorative materials and features chemical adhesion to tooth structure and long-term fluoride release. This article describes a 12-month clinical evaluation of Fuji Ortho for the direct bonding of orthodontic (metal) brackets with System 1+ (Ormco Corp.) as a control. Three failures of Fuji Ortho occurred from a sample of 60 (5%), with five failures of the composite resin from a sample of 60 (8.3%). No statistical significance was seen between these results. Fuji Ortho is a satisfactory adhesive for the direct bonding of orthodontic brackets where there are no occlusal interferences.

  17. International Conference on Harmonisation: guidance on Q1D bracketing and matrixing designs for stability testing of new drug substances and products; availability. Notice.

    Science.gov (United States)

    2003-01-16

    The Food and Drug Administration (FDA) is announcing the availability of a guidance entitled "Q1D Bracketing and Matrixing Designs for Stability Testing of New Drug Substances and Products." The guidance was prepared under the auspices of the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH). This guidance is an annex to an ICH guidance entitled "Q1A(R) Stability Testing of New Drug Substances and Products" (66 FR 56332, November 7, 2001). It is intended to provide guidance on the application of reduced designs (i.e., bracketing and matrixing) for stability studies conducted in accordance with the principles outlined in ICH Q1A(R).

  18. The Optimization Design of Door Connecting Rod Bracket Structure of Civil Aircraft%民用飞机舱门连杆支架优化研究

    Institute of Scientific and Technical Information of China (English)

    袁修起

    2014-01-01

    The cabin latch mechanism of civil aircraft is to prevent the door accidentally open parts. When a jam occurs forced operation, it will produce a greater internal force. The equipment door latch mechanism is all stem shape and load is small except the connecting rod bracket. Connecting rod bracket structure is complex and load is bigger. Based on analyzingresistance load ,using the finite element analysis software HyperMesh and Opti-Struct , three kinds of structure forms of connecting rod bracket are simulated. With comparison and analysis, connecting rod bracket structure satisfied equipment doors functional requirements and prototype test purpose, which provides reference for the follow-up of the real product design.%民用飞机舱门闩机构是防止舱门意外开启的机构部件。当机构发生卡阻且强制操作时,将产生较大的内力。在设备舱门闩机构中除连杆支架外都是杆形件且载荷较小,连杆支架结构形式复杂且载荷较大。在分析机构卡阻载荷的基础上使用有限元分析软件HyperMesh和Opti-Struct对三种结构形式的连杆支架进行了数值模拟。通过对比分析,得到了满足样机设备舱门功能要求和试验目的的连杆支架形式,为后续真实产品的设计提供参考。

  19. Corrosion Inhibitory Ability of Ocimum Sanctum Linn (Tulsi Rinse on Ion Release from Orthodontic Brack-ets in Some Mouthwashes: An Invitro Study

    Directory of Open Access Journals (Sweden)

    Roopal Patel, Sheron Bhanat, Dolly Patel, Bhadra Shah

    2014-01-01

    Full Text Available Introduction: In the oral environment, orthodontic appliances are exposed to potentially damaging physical and chemical agents which may cause metallic corrosion. Corrosion will occur continuously in mouth, due to release of irons with abrasion by food, liquids etc. The purpose of this study was to measure the amount of metal ion release from orthodontic brackets when kept in different mouthwashes and effect of tulsi rinse on ion release when combined with different mouthwashes. Methods: Three hundred and twenty stainless steel brackets (0.022” were divided randomly into 8 equal groups and immersed in Mouthwash-A and, Mouthwash-B and mouthwash-C and distilled deionized water. These mouthwashes and distilled deionized water were all sepa-rately mixed with tulsi rinse and incubated at 37°C for 45 days. Nickel, Chromium, iron, copper and manganese released from the orthodontic brackets were measured with an inductively coupled plasma spectrometer. Results: Ion release in deionized water was higher (p<0.05 than in the 3 mouthwashes. Higher ion release was also found with Mouthwash-B compared with other 2 mouthwashes. There is no difference (p>0.05 in nickel, chromium, iron and copper ion release in the Mouthwash-A and Mouthwash-C. Tulsi rinse showed significant reduction (p<0.05 in all ion release in 3 mouthwashes used along with distilled deionzed water group. Conclusion: If ion release is concerned, Mouthwash-C mixed with tulsi rinse might be better option than Mouthwash-A as well as Mouthwash-B for orthodontic patients with stainless steel brackets.

  20. Comparison of pain between application smartclipTM 3MXTM self-locking brackets and brackets of traditional MBTTM%应用SmartclipTM 3MXTM自锁托槽与传统MBTTM托槽疼痛程度的比较

    Institute of Scientific and Technical Information of China (English)

    李庆祝

    2013-01-01

    目的 探讨应用SmartclipTM 3MXTM自锁托槽与传统MBTTM托槽疼痛程度.方法 选取采用不拔牙正畸治疗的72例患者作为观察对象,并按数字表法随机分为两组,每组36例,一组采用自锁托槽,另一组采用传统托槽.通过问卷调查的方式了解患者在正畸治疗一周内的疼痛情况,包括正畸疼痛,软组织刺痛以及其强度对于患者正常生活带来的影响.结果 问卷表反馈率94.4%.自锁托槽组与传统托槽组疼痛程度相似.但与时间相关,其中正畸治疗3h后疼痛明显,1d时间疼痛最剧烈并一直持续到第3d,往后疼痛减轻,1周左右疼痛缓解.结论 自锁托槽与传统托槽在疼痛程度上差异不大,但与矫治力有关,临床上应注意轻力的使用.%Objective To study the self-locking brackets SmartclipTM 3MXTM MBTTM brackets and traditional pain comparison.Methods 72 patients with non-extraction orthodontic treatment were randomly divided into two groups,a group treated with self-locking brackets,the other group treated with traditional care slot.Patients in orthodontic treatment of pain within a week were inoestigated by way of a questionnaire survey,including orthodontic pain,soft tissue irritation,and the strength of a normal life for patients with the impact.Results Questionnaire response rate was 94.4%.The level of pain was similar in self-ligating bracket group and the traditional bracket group.However,time-related,including pain after orthodontic treatment was 3h,1 d time,the most intense pain and continued to 3d,back pain relief,1w about pain relief.Conclusion Self-locking brackets and brackets have noobvious pain intensity differences,but related with orthodontic force to the clinical use of force should pay attention to light.

  1. Finite Element Analysis on Rear Mounting Bracket of Hybrid Engine%混联式发动机后悬置支架有限元分析

    Institute of Scientific and Technical Information of China (English)

    刘善锷; 陈诗库; 张彦斌; 刘汨

    2015-01-01

    The engine rear mounting bracket is an important bearing member of powertrain,its strength must meet all requirements of all extreme conditions. The authors model and simulate the engine rear suspension bracket with the finite element analysis by use of Solidworks and Simulation softwares, as well as optimize the bracket structure. The results show that the optimize support can effectively reduce the stress of the key position,improve the safety performance of the engine mounting system.%发动机后悬置支架是动力总成的重要承载部件,其强度必须满足各种极限工况要求。本文利用Solidworks软件对发动机后悬置支架进行建模,利用Simulation软件进行有限元分析与结构优化。结果表明,优化后的支架有效地降低了关键部位的应力,提高了发动机悬置系统的安全性能。

  2. Effect of Dental Chair Light on Enamel Bonding of Orthodontic Brackets Using Light Cure Based Adhesive System: An In-Vitro Study

    Science.gov (United States)

    Tiwari, Anil; Shyagali, Tarulatha; Kohli, Sarvraj; Joshi, Rishi; Gupta, Abhishek; Tiwari, Rana

    2016-01-01

    Aim: The aim of this in vitro study was to evaluate the influence of the Dental chair light on the bond strength of light cured composite resin. Materials and Methods: Sixty therapeutically extracted human premolar teeth were randomly allocated to two groups of 30 specimens each. In both groups light cured composite resin (Transbond XT) and MBT premolar metal brackets (3M Unitek) was used to bond brackets. In group I and II light curing was done using Light-emitting diode light curing units without and with the dental chair light respectively. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested for shear bond strength and Adhesive Remnant Index (ARI) scores. Data was subjected to Mann Whitney U statistical test. Results: Results indicated that there was significantly higher shear bond strength (7.71 ± 1.90) for the Group II (composite cured with LED and dental chair light) compared with Group I (composite cured with LED LCU only) (5.74 ± 1.13).the obtained difference was statistically significant. There was no statistical significant difference between ARI scores in between the groups. Conclusions: light cure bonding with dental chair light switched on will produce greater bond strength than the conventional bonding. However, the ARI score were similar to both the groups. It is advised that the inexperienced orthodontist should always switch off the dental chair light while bonding for enough working time during the bracket placement. PMID:28077886

  3. IN VITRO Cr(VI SPECIATION IN SYNTHETIC SALIVA AFTER RELEASING FROM ORTHODONTIC BRACKETS USING SILICA-APTES SEPARATION AND GF AAS DETERMINATION

    Directory of Open Access Journals (Sweden)

    Maciel S. Luz

    Full Text Available A method for Cr(VI speciation in synthetic saliva after releasing from orthodontic brackets, using silica nanoparticles organofunctionalized with (3-aminopropyltriethoxysilane (APTES for Cr(III/Cr(VI separation and GF AAS determination is proposed. Under the optimized conditions, Cr(VI speciation was performed using 150 mg of silica organofunctionalized with 2.0% (v v-1 of APTES at pH 8. It was observed different sensitivity when calibrations of GF AAS were performed using Cr(III or Cr(VI as standard solutions. Consequently, calibrations using stoichiometric mixtures (Cr(III + Cr(VI were used for total Cr determination and calibration using Cr(VI was used only for the determination of this specie. The reliability of the proposed silica-APTES separation procedure and GF AAS determination was checked by addition of both species in synthetic saliva. Recoveries ranging from 97 to 110% were obtained. The repeatability, based on the relative standard deviation (RSD inter days was less than 6%. A corrosion test was carried out on 20 orthodontic brackets from two different models, after immersion in synthetic saliva (pH=6.0 at 37 °C with agitation (125 rpm for 24 h. It was observed that about 40% of the total chromium released from the analyzed orthodontic brackets was Cr(VI.

  4. The design of the motor bracket for reduction of structure-borne noise in package air-conditioner

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Hyoun Jin; Lee, Sung Jin; Oh, Jae Eung [Hanyang University, Seoul (Korea, Republic of); Kang, Tae Ho [WiniaMando, Asan (Korea, Republic of); Lee, Jung Yoon [Kyonggi University, Suwon (Korea, Republic of)

    2006-02-15

    As the economic power is improved and the customer's demand is hard to please, the noise and vibration is the most important yardstick that can determine the quality of the product. Especially, as the air-conditioner's demand increase suddenly, the product of quality and the noise is becoming a decisive factor of determining whether purchase the product or not. Therefore, every manufactory is investing a lot of money and research to cut down the unpleasantness induced from noise and vibration. And they are emphasizing their product's difference by advertising a silence very actively. With these reason, the demand of a silent indoor air-conditioner is the essential research filed when the product is developed. In this study, the noise and vibration is visualized in the space and frequency domain by using experimental methods such as Operational Deflection Shape (ODS), modal testing and sound intensity. Also the location of noise source and its characteristic is analyzed in an acoustical point of view to reduce the structure borne noise that come from the fan motor, and the pertinent control method is suggested. Furthermore, the most suitable shape of the motor bracket is suggested by applying FEM and DOE (Design of Experiments) in the noise and vibration point a view.

  5. Design of progressive die for spacer positioning bracket%定位支架级进模设计

    Institute of Scientific and Technical Information of China (English)

    李昌雪; 李捷

    2011-01-01

    对定位支架的成形工艺进行分析,制定了合理的冲压工艺,设计了生产定位支架的精密级进模,介绍了模具结构特点和零件端部圆弧与Z形弯曲结构,合理布置浮顶镶件控制成形.实践证明:模具结构合理、可靠,生产的零件合格,对类似零件的成形有一定的参考价值.%Based on analysis on the forming technique of a spacer bracket, a stamping process was determined and a precision progressive die was developed. The die structure features, the arc at the part end and the Z-shaped bend structure were presented. The die is characteristic with application of floating ejector pins in control of forming.

  6. Salt Spray Test to Determine Galvanic Corrosion Levels of Electroless Nickel Connectors Mounted on an Aluminum Bracket

    Science.gov (United States)

    Rolin, T. D.; Hodge, R. E.; Torres, P. D.; Jones, D. D.; Laird, K. R.

    2014-01-01

    During preliminary vehicle design reviews, requests were made to change flight termination systems from an electroless nickel (EN) connector coating to a zinc-nickel (ZN) plating. The reason for these changes was due to a new NASA-STD-6012 corrosion requirement where connectors must meet the performance requirement of 168 hr of exposure to salt spray. The specification for class F connectors, MIL-DTL-38999, certifies the EN coating will meet a 48-hr salt spray test, whereas the ZN is certified to meet a 168-hr salt spray test. The ZN finish is a concern because Marshall Space Flight Center has no flight experience with ZN-finished connectors, and MSFC-STD-3012 indicates that zinc and zinc alloys should not be used. The purpose of this test was to run a 168-hr salt spray test to verify the electrical and mechanical integrity of the EN connectors and officially document the results. The salt spray test was conducted per ASTM B117 on several MIL-DTL-38999 flight-like connectors mounted to an aluminum 6061-T6 bracket that was alodined. The configuration, mounting techniques, electrical checks, and materials used were typical of flight and ground support equipment.

  7. Design of the Injection Mold for Plastic Pipe Bracket%塑管支架注射模设计

    Institute of Scientific and Technical Information of China (English)

    陈焕东; 张兰英

    2012-01-01

    通过对塑料支架塑件结构的分析,介绍了该塑件注射模的成型工艺过程,提出了模具采用塑件侧面作为分型面的方案,使模具在采用斜导柱侧向抽芯机构脱模时,其结构简单实用,易于加工调试,解决了注射成型后塑件的脱模的问题。经大批量的生产检验,该模具结构合理,生产效率高,塑件质量好。%Based on the analysis of structure of product of plastic bracket, introduced the injection mold of the molding process, put forward by product as mold side parting surface scheme, the die in the inclined guide pillar side pulling-core mechanism of stripping, the structure is simple and practical, easy processing and debugging, solved after injection molding product release problemo The products in large quantities of production test, the die structure is reasonable, high production efficiency, good product quality.

  8. Control of White Spot Lesion Adjacent to Orthodontic Bracket with Use of Fluoride Varnish or Chlorhexidine Gel

    Directory of Open Access Journals (Sweden)

    Manuel Restrepo

    2015-01-01

    Full Text Available The aims of this study were to compare the effectiveness of fluoride varnish and chlorhexidine gel in controlling white spot lesions (WSLs adjacent to orthodontic brackets and to compare the ability of Quantitative Light-Induced Fluorescence (QLF to measure mineral uptake with that of transverse microradiography (TMR. Thirty premolars with artificially induced WSLs were randomly assigned to three groups: (1 two applications of 5% NaF-varnish (F, with one-week interval, (2 two applications of 2% chlorhexidine gel (CHX, with one-week interval, and (3 control (CO, no treatment. QLF was used to measure changes in fluorescence before and after caries induction, 1 week after each application and 1, 2, and 3 months after the last application of F or CHX. TMR was performed to quantify lesion depth and mineral content after caries induction to evaluate the effects of F, CHX, and CO 3 months after the last application of agents. The data were analyzed by repeated measures ANOVA and Tukey’s test. All treatments increased the mineral content during the experimental period; however, F induced faster remineralization than CHX. The correlation between QLF and TMR was significantly moderate. Two applications of fluoride varnish or 2% chlorhexidine gel at one-week intervals were effective in controlling WSLs.

  9. Control of white spot lesion adjacent to orthodontic bracket with use of fluoride varnish or chlorhexidine gel.

    Science.gov (United States)

    Restrepo, Manuel; Bussaneli, Diego G; Jeremias, Fabiano; Cordeiro, Rita C L; Magalhães, Ana C; Palomari Spolidorio, Denise M; Santos-Pinto, Lourdes

    2015-01-01

    The aims of this study were to compare the effectiveness of fluoride varnish and chlorhexidine gel in controlling white spot lesions (WSLs) adjacent to orthodontic brackets and to compare the ability of Quantitative Light-Induced Fluorescence (QLF) to measure mineral uptake with that of transverse microradiography (TMR). Thirty premolars with artificially induced WSLs were randomly assigned to three groups: (1) two applications of 5% NaF-varnish (F), with one-week interval, (2) two applications of 2% chlorhexidine gel (CHX), with one-week interval, and (3) control (CO), no treatment. QLF was used to measure changes in fluorescence before and after caries induction, 1 week after each application and 1, 2, and 3 months after the last application of F or CHX. TMR was performed to quantify lesion depth and mineral content after caries induction to evaluate the effects of F, CHX, and CO 3 months after the last application of agents. The data were analyzed by repeated measures ANOVA and Tukey's test. All treatments increased the mineral content during the experimental period; however, F induced faster remineralization than CHX. The correlation between QLF and TMR was significantly moderate. Two applications of fluoride varnish or 2% chlorhexidine gel at one-week intervals were effective in controlling WSLs.

  10. Effects of procedures of remineralization around orthodontics bracket bonded by self-etching primer on its shear bond strength

    Science.gov (United States)

    Al-Suleiman, Mahmoud; Silikas, Nick; Watts, David

    2012-01-01

    Aim: To evaluate the effect of the application of either fluoride varnish (FV) or amorphous calcium phosphate (ACP) as preventive method on shear bond strength (SBS) at the same time of their bonding in vitro using self-etching primer (SEP) as an agent for enamel pre-treatment FV. Materials and Methods: Sixty human bicuspids were randomly divided into five groups: G1 was rubbed by SEP for 5 s, G2 for 5 s by SEP and ACP, G3 for 10 s by SEP and ACP, G4 for 5 s by SEP and FV, and G5 for 10 s by SEP and FV. Stainless steel metal brackets were bonded. A Zwick/Roell Z020 Universal Testing Machine (Zwick GmbH and Co, Germany) with a 500 N load cell was used to test SBS. SBS values were analyzed using one-way analysis of variance (ANOVA) and Tukey's post hoc tests (P≤0.05). Differences in adhesive remnant index (ARI) values between groups were calculated. Results: The mean SBS values were 10.00±4.48 MPa, 5.71±4.3 MPa, 7.47±4.44 MPa, 4.4±2.39 MPa, and 3.98±0.83 MPa for groups 1–5, respectively. Significant differences in SBS values between all groups were found. The mean SBS values of groups 2, 4, and 5 were significantly lower than that of the G1. No significant difference was found between G3 and G1. Significant difference in ARI between the groups was found (P<0.001) and G1 had a significantly higher ARI. Conclusion: The results suggested that the application of ACP at the same time of using SEP for 10 s has no effect on SBS. PMID:24987629

  11. Comparison of shear bond strength of orthodontic brackets bonded using two different hydrophilic primers: An in vitro study

    Directory of Open Access Journals (Sweden)

    M Kumaraswamy Anand

    2014-01-01

    Full Text Available Context: Salivary control and maintenance of a dry operating field is a prime requisite of orthodontic bonding. Moisture insensitive primer (MIP with a clinical significant bond strength values have a better edge over the conventional hydrophobic bonding systems. Aim: The aim of this study is to investigate the effectiveness of two hydrophilic primers with respect to conventional hydrophobic primer by comparing their shear bond strength (SBS and adhesive-failure locations after contamination with saliva and saliva substitute. Materials and Methods: A total of 150 extracted human premolars were randomly divided into five group s ; Group A (Transbond MIP/saliva substitute, Group B (Opal Primo/saliva substitute, Group C (Transbond MIP/natural saliva, Group D (Opal Primo/natural saliva, control group - Group E (Transbond XT/dry, adhesive-Transbond XT used for all five groups and bonded using stainless steel brackets. Shear forces were applied to the samples with a universal testing machine. SBSs was measured in megapascals. The mode of bond failure was determined using the adhesive remnant index (ARI. Results: The mean SBS produced by Transbond MIP was higher than Opal Primo, which was statistically significant according to one-way analysis of variance. Both the tested groups showed lesser bond strength values than Transbond XT (the control. ARI scores revealed that there was no statistically significant difference in the site of bond failure between study groups. ARI scores were found to be lower for study groups suggesting adhesive failure, compared to higher ARI scores for the control group suggesting cohesive failure. Conclusion: Transbond XT adhesive with Transbond MIP or Opal Primo have clinically acceptable bond strength in wet fields. Opal Primo is a viable option to use as a hydrophilic primer clinically.

  12. Er:YAG pre-treatment for bonding of orthodontic bracket: 1 year of in vitro treatment

    Science.gov (United States)

    de Jesus Tavarez, Rudys Rodolfo; Lima Bezerra, Gisele; de Souza Penha, Karla Janilee; Torres, Carlos Rocha Gomes; Firoozmand, Leily Macedo

    2017-01-01

    Objective The aim of this study was to evaluate in vitro bond strength of metal brackets bonded with: total etch, total etch with erbium: yttrium aluminum garnet laser (Er:YAG) and self-etching adhesive systems, submitted to thermal-mechanical cycling, simulating 1 year of orthodontic treatment. Materials and methods For the study, 80 bovine incisors were randomly divided into 3 experimental groups (n=16 each): XT- acid etching + Transbond XT, XT/Er:YAG- Transbond XT associated with Er:YAG laser irradiation (λ=2.94 μm, 60 mJ, 10 Hz) and SEP- Transbond Plus Self Etching Primer. Samples were submitted to thermal-mechanical cycling, simulating 1 year of orthodontic treatment. Afterward, the shear bond strength test was performed in a universal test machine at a speed of 0.5mm/min. Samples were evaluated under a stereomicroscope and by scanning electron microscopy for analysis of enamel surface and adhesive remnant index. Data were analyzed using Kruskal–Wallis and Mann–Whitney (with Bonferroni correction) statistical tests. Results Statistically significant difference was observed between the groups studied (p<0.05). Groups XT and SEP showed the highest bond strength values, without statistical difference between them, while group XT/Er:YAG showed reduction in bond strength values. Higher frequency of adhesive failures between enamel and adhesive system was verified for groups XT and XT/Er:YAG. Conclusion The conventional (XT) and self-etching (SEP) adhesive systems showed mean bond strength values, similar between them, whereas the previous application of Er:YAG laser promoted the lowest bond strength values.

  13. Desempenho de um microtrator utilizando-se motores com diferentes alternativas energéticas = Performance of a microtractor using engines with different energetic alternatives

    Directory of Open Access Journals (Sweden)

    Denílson Eduardo Rodrigues

    2006-01-01

    Full Text Available Neste trabalho avaliou-se o desempenho de um microtrator equipado com três diferentes tipos de acionamento. Um mesmo chassi de um microtrator foi instalado, alternadamente, com um motor elétrico trifásico (MCA, um motor elétrico de corrente contínua (MCC e com um motor de combustão interna (MCI. Os ensaios do microtrator com cada um dos motores permitiram a determinação da força de tração máxima, da velocidade de deslocamento, do consumo de combustível e a patinagem dos rodados. O MCC desenvolveu maior força de tração, sendo 22% superior aos demais. O consumo específico de energia para os microtratores decresceu com o aumento da patinagem. This study evaluated the performance of a microtractor implemented in three different operational types. A microtractor chassis was alternately operated with a three-phase electric engine (MCA, a direct-current electric engine (MCC and an internal combustion engine (MCI. The rehearsals of the microtractor implemented in each one of the engines allowed determinations of the maximum tractive force, the forward speed and the fuel consumption in wheel skiddings. The MCC developed greater snatch force, being 22% superior to the others. The specific consumption on energy for the microtractors decreased as the skiddings increased.

  14. Processamento de nitreto de silício utilizando-se técnicas de filtração coloidal

    Directory of Open Access Journals (Sweden)

    Castanho S. Mello

    1998-01-01

    Full Text Available Apresentam-se os estudos relacionados ao processamento de pós de Si3N4, sistematizando-se cada etapa dos processos de conformação por colagem e colagem sob pressão. A avaliação das propriedades eletroforéticas e do comportamento reológico possibilitou a preparação de suspensões aquosas concentradas de Si3N4 estáveis e homogêneas. Os estudos cinéticos foram realizados em função da pressão aplicada e dos aditivos de sinterização. As análises de superfície dos pós (XPS demonstraram que com o controle dos parâmetros estudados é possível a obtenção de peças a verde de Si3N4 com baixa oxidação superficial. Produziu-se cerâmicas densas de Si3N4 (96%DT com boas propriedades mecânicas (E = 312 GPa, K IC = 6,2 MPa.m1/2 , tanto a temperatura ambiente como em altas temperaturas (1200 e 1300°C, compatíveis com os valores reportados na literatura.

  15. Produção e caracterização de aromas de frutas por microrganismos pectinoliticos utilizando-se residuos agroindustriais.

    OpenAIRE

    Mariana Uenojo

    2003-01-01

    Resumo: As pectinases foram algumas das primeiras enzimas a serem utilizadas comercialmente nas preparações de vinhos e sucos de frutas na década de 1930 e seu uso tem aumentado consideravelmente, especialmente nas indústrias de alimentos, bebidas e vinhos, têxtil e de papel e celulose. Atualmente essas enzimas correspondem à cerca de 20% do mercado mundial de enzimas e são produzidas naturalmente por plantas, fungos, leveduras e bactérias. Estes microrganismos podem ser inoculados em meios c...

  16. Evaluation of renal allografts using {sup 99m} Tc mononuclear leukocytes; Avaliacao de transplantes renais utilizando-se {sup 99m} Tc-leucocitos mononucleares

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Sergio Augusto Lopes de; Martins, Flavia Paiva Proenca; Carvalho, Antonio Carlos Pires; Gutfilen, Bianca [Universidade Federal, Rio de Janeiro, RJ (Brazil). Faculdade de Medicina. Dept. de Radiologia]. E-mail: sergioalsouza@ufrj.br; Goncalves, Renato Torres; Pontes, Daniela Salomao [Hospital Universitario Clementino Fraga Filho, Rio de Janeiro, RJ (Brazil). Servico de Nefrologia; Fonseca, Lea Mirian Barbosa da [Universidade Federal, Rio de Janeiro, RJ (Brazil). Faculdade de Medicina. Dept. de Medicina Nuclear

    2004-02-01

    Renal allograft acute rejection must be promptly diagnosed since its reversibility is related to the readiness in which treatment is initiated. The aim of this study was: to establish a quantitative method to evaluate kidney rejection and acute tubular necrosis (Attn); to assess the potential role of {sup 99m} Tc-mononuclear leukocytes scintigraphy in the diagnosis of renal rejection and differential diagnosis of Attn. One hundred and sixty studies were performed in 80 renal transplant patients at the first and fifth day after transplantation. Autologous cells were used for labeling. Images were obtained at 30 minutes, 3 hours and 24 hours after intravenous administration of 444 MBq (12 mCi) of labeled cells. There was abnormal labeled cells uptake in 27 of 31 cases of rejection and in 6 of 8 cases of Attn. The results of each patient were compared with clinical findings. Doppler scanning detected 18 of 31 cases of rejection. Rejection diagnosis sensitivity and specificity rates using scintigraphy were 87.1 per cent and 100 per cent, respectively, and 58.1 per cent and 100 per cent, respectively using ultrasound. Renal biopsy was performed in eight patients which demonstrated seven cases of rejection and one case of ATN. These results suggest that {sup 99m} Tc-mononuclear leukocytes imaging may be useful in the early diagnosis of rejection and in the differential diagnosis of ATN. (author)

  17. Reduções enantiosseletivas de cetonas utilizando-se fermento de pão Enantioselective reductions of ketones using baker's yeast

    Directory of Open Access Journals (Sweden)

    José Augusto R. Rodrigues

    2001-12-01

    Full Text Available Baker's yeast has been successful employed to reduce carbonyl compounds carrying appropriated substituents at distances under the electronic influence of the keto group. High yields and enantiomeric excess (ee were obtained with 1,2-alkanedione, 1,2-alkanedione (2-O-methyloxime and 1,3-alkanedione. Potential chiral building blocks were obtained and applied for stereoselective synthesis of valuable compounds. Evidence for a free radical chain process was obtained with baker's yeast reduction of a-iodoacetophenone using radical inhibitors.

  18. Tratamento de águas residuárias da suinocultura utilizando-se filtros orgânicos Treatment of swine wastewater using organic filters

    Directory of Open Access Journals (Sweden)

    Viviane dos Santos Brandão

    2000-12-01

    Full Text Available O tratamento primário da água residuária de suinocultura pode ser feito por filtragem; para isto, torna-se oportuno o estudo de materiais alternativos a serem utilizados como meio filtrante e, com este intuito, foram utilizados o bagaço de cana-de-açúcar, a casca de arroz, a casca de café, o fino de carvão vegetal, o sabugo de milho e a serragem de madeira, acondicionados em tubos de PVC de diâmetro de 100 mm, constituindo colunas de 500 mm de altura. O sistema de filtragem foi mantido sob escoamento permanente, com fluxo em meio saturado, e pequena ou nenhuma alteração foi detectada na concentração de N-total, Ca, Mg e Zn no efluente do filtro, enquanto que as concentrações de P-total, Na e K aumentaram no efluente obtido em filtros de casca de arroz, casca de café e sabugo de milho. Significativa redução na concentração de Cu foi constatada para todos os materiais utilizados como filtro, atingindo-se eficiência de remoção de até 43,6%. Eficiências de remoção superiores a 90% foram obtidas para sólidos sedimentáveis enquanto a remoção de sólidos totais ficou abaixo de 33,0%.The primary treatment of swine wastewater can be done by filtration. To this end, the study of alternative materials as a filter media is necessary. With this objective, rice husk, coffee straw, sugar-cane trash, triturated corncob, wood sawdust and fine vegetable coal were used as media, conditioned in PVC tubes of 100 mm in diameter and 500 mm in height. The filtering system was maintained under saturated flow conditions. Little or no change was detected in the concentration of N-total, Ca, Mg and Zn in the effluent of the filter, although the concentration of P-total and K increased in the effluents of the filters of rice husk, coffee straw, triturate corncob, reaching a maximum removal efficiency of 43.6%. Removal efficiencies of sedimentable solids higher than 90.0% were obtained in all materials employed as a filtration media, although total solids removal efficiency was less than 33.0%.

  19. DEGRADAÇÃO FOTOCATALÍTICA DE CORANTE UTILIZANDO-SE NANOCOMPÓSITO TiO2/ÓXIDO DE

    Directory of Open Access Journals (Sweden)

    Arlene B. S. Nossol

    2016-07-01

    Full Text Available In this work the sol-gel method was used to synthesize a nanocomposite containing TiO2 and graphene oxide (GO. The photocatalytic activity of the TiO2/GO nanocomposite was evaluated regarding the degradation of a reactive dye (reactive black 5 in aqueous solution using processes assisted by UV-A radiation. Under these conditions the nanocomposite showed higher degradation efficiency than the reference photocatalyst (Degussa P25 TiO2, mainly due to the high degradation capacity of the synthesized TiO2 nanoparticles. Although contradictory to several reports in the specialized literature, no synergistic effect was observed between the nanocomposite components.

  20. Controle de ferrugem asiática da soja utilizando-se diferentes pontas de pulverização em Maracaju-MS

    Directory of Open Access Journals (Sweden)

    Jackeline Matos do Nascimento

    2009-01-01

    Full Text Available En la presente investigación realizada en Maracaju, en el estado de Mato Grosso do Sul, Brasil, fue estudiado el efecto de puntas y horarios de aplicación para el control de la Roya asiática de la soya. Se evaluaron cuatro puntas de pulverización: chorro plano de uso ampliado, chorro plano doble, chorro plano deflector y chorro plano deflector doble. Las aplicaciones ocurrieron en los horarios de 14:00 y 17:30h con un pulverizador de espaldas a presión constante (CO2. El fungicida utilizado fue el epoxiconazole y piraclostrobina, en la dosis de 0,5 L·ha-1 del producto comercial. El delineamiento experimental fue el de bloques al azar, con cuatro repeticiones, en un esquema de parcelas subdivididas, donde la parcela fue el horario y las subparcelas las puntas. Fueron colectados 30 folíolos en los tercios superior, medio e inferior de la planta, para evaluar el número de lesiones, uredíneas, incidencia y severidad de la enfermedad. En la aplicación realizada en el horario de las 14:00h con la punta chorro plano deflector, las plantas presentaron mayor número de lesiones y uredíneas en el tercio medio, cuando fue comparada con las puntas chorro plano deflector doble y chorro plano doble. No fueron detectadas diferencias significativas en relación a la masa de mil granos y la producción.

  1. Sutura arterial com técnicas contínua e de pontos separados, utilizando-se os fios polipropilene e polidioxanone: estudo experimental em coelhos

    OpenAIRE

    Campos, Nelson Leonardo Kerdahi Leite de [UNESP; Ueda, Anete Kinumi; Moraes-Silva,Marcos Augusto de

    2003-01-01

    OBJETIVO: Observar o comportamento da sutura arterial em aortas abdominais de coelhos em crescimento, comparando-se as técnicas contínua e com pontos separados, empregando-se dois tipos de fios: Polipropilene 7-0 (inabsorvível) e Polidioxanone 7-0 (absorvível). MÉTODOS: Grupos: GI - Controle (sem sutura); GII - Polipropilene, Pontos Separados; GIII - Polipropilene, Contínua; GIV - Polidioxanone, Pontos Separados e GV - Polidioxanone, Contínua. Cada grupo foi subdividido em quatro Momentos de ...

  2. Desenvolvimento de um sistema integrado para genotipagem de protozoários patogênicos utilizando-se genes ortólogos universais

    OpenAIRE

    Tschoeke, Diogo Antônio

    2010-01-01

    Este trabalho teve com objetivo o desenvolvimento e a validação/aplicação de um sistema integrado de genotipagem de protozoários, utilizando uma abordagem multidisciplinar envolvendo, PCR multiplex e análise bioinformática envolvendo evolução e filogenia molecular. Para isso, trinta e seis genes ortólogos universal (UOG) foram identificados e usados como marcadores para genotipagem de protozoários parasitas, a nível inter-específico. Temos extraído os dados genéticos de gene...

  3. Determination of the biodiesel acidity index by potentiometric titration by using different methods; Determinacao do indice de acidez de biodiesel por titulacao potenciometrica utilizando-se diferentes metodos

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Mary Ane; Sobral, Sidney Pereira; Borges, Paulo Paschoal [Instituto Nacional de Metrologia, Normalizacao e Qualidade Industrial (DIMCI/INMETRO), Duque de Caxias, RJ (Brazil). Diretoria de Metrologia Cientifica e Industrial], E-mail: magoncalves@inmetro.gov.br

    2009-07-01

    This work determined the index of the soybean/fat bio diesel through the potentiometric titration. Four different methods were used with variation of solvent and electrodes. The results were compared by F and t (Student) and it was verified that they were agreed in a 95% confidence interval.

  4. Shear bond strength of recycled metal brackets%金属托槽重复利用的抗剪切强度

    Institute of Scientific and Technical Information of China (English)

    刘新强; 李正明; 马长柏; 张丁; 孙志辉

    2008-01-01

    BACKGROUND: Bracket dropping is often seen in clinic. Can these shed brackets be used again; what should be done to treat these brackets; is the bond strength of these recycled brackets different from those new ones, these questions are often concerned by orthodontists in their clinic and are the purpose of our study as well.OBJECTIVE: To evaluate the shear bond strength and compare two base-cure methods of recycled brackets. DESIGN: Grouping control study. SITTING: Department of Orthodontics, the Affiliated Hospital of Medical College, Qingdao University; Department of Materials, Dental School, Beijing University. MATERIALS: The teeth were collected from Oral Surgery, the Affiliated Hospital of Medical College, Qingdao University. The age was from 11 to 19 years. The gender was half male and half female. Intact enamel of the crown was required, but decayed, fracture, tetracycline pigmentation teeth or fluorosis teeth were excluded. Patients provided the confirmed consent for this experiment.METHODS: The experiment was carried out in Stomatology College of Peaking University in December 2005. Thirty ex vivo teeth were selected randomly from those prepared enamel surfaces, used as sample for rebounding. The edgewise brackets of swallow-tailed brackets were bonded on each tooth and rebonded after 24 hours. The teeth were cleaned and divided randomly into 3 groups. There were 10 teeth in each group. Group 1 was bonded with new brackets; group 2 with recycled brackets whose adhesive remnant were burned and got rid of; group 3 with recycled brackets whose adhesive remnant in the groove of the base were stored. Bracket was provided by Standard edgewise, Orsu Company, Hangzhou, China. After 24 hours, the shear bond strength was tested with material testing machine (Autogragh, Shimadzu, Japan). Adhesive remnant index (ARI) was added up. MAIN OUTCOME MEASURES: Shear strength of old metal bracket after rebonding and adhesive remnant.RESULTS: ① Shear bond strength: The

  5. A comparative assessment of torque capabilities between lingual and labial brackets using three-dimension finite element%唇舌侧托槽转矩控制性能的有限元对比分析

    Institute of Scientific and Technical Information of China (English)

    黄思源; 周吉; 黄跃

    2016-01-01

    目的:分析唇舌侧托槽转矩控制性能的差异,同时探讨不同材质不同尺寸的弓丝对舌侧托槽转矩控制的影响规律。方法:建立左上尖牙到右上尖牙的唇舌侧托槽三维有限元模型,在弓丝尺寸及材质不同的情况下,模拟临床左上中切牙转矩加载±20°。结果:随着转矩角度的增大,唇舌侧托槽转矩值逐渐增大,舌侧托槽转矩值为唇侧托槽的3~5倍;0.48 mm ×0.64 mm 弓丝的转矩值大于0.43 mm ×0.64 mm;弓丝尺寸相同时,不锈钢丝(SS),β-钛丝(TMA),镍钛丝(NiTi),转矩值依次减小。结论:唇舌侧托槽转矩均随着转矩角度和弓丝的弹性模量的增大而增大;在相同的转矩角度下,舌侧托槽产生的转矩值大于唇侧托槽;舌侧托槽的转矩值与弓丝尺寸及材质有关。%Objective:To analyse the difference of torque performance between lingual and labial brackets as well as the influence of the archwires of different materials with different dimension on the torque capability of lingual brackets.Methods:The 3D finite mo-del of lingual and labial brackets from the right upper canine to the left upper canine was established,all brackets were with 0.56 mm slot size.The center of the bracket slot of the left upper central incisor was used as the central point and the two brackets were rotated clockwise and counterclockwise with a rotation angle of ±20°along the horizontal axis of bracket slot.The torque load on the left up-per central incisors with different materials and dimensions of the archwires was simulated.Results:The torque force of both lingual and labial brackets increased with the increase of rotation angle and the elastic modulus of archwire.The lingual archwire generated torque force was nearly 3 -5 times more than the labial system under the same torque angle.The torque value generated with 0.48 mm ×0.64 mm archwires was greater than 0.43 mm ×0.64 mm

  6. Comparison of two methods of visual magnification for removal of adhesive flash during bracket placement using two types of orthodontic bonding agents

    Science.gov (United States)

    Alencar, Estefania Queiroga de Santana e; Nobrega, Maria de Lourdes Martins; Dametto, Fabio Roberto; dos Santos, Patrícia Bittencourt Dutra; Pinheiro, Fabio Henrique de Sá Leitão

    2016-01-01

    ABSTRACT Objective: This study aimed to evaluate the effectiveness of two methods of visual magnification (operating microscope and light head magnifying glass) for removal of composite flash around orthodontic metal brackets. Material and Methods: Brackets were bonded in the center of the clinical crown of sixty well-preserved human premolars. Half of the sample was bonded with conventional Transbond XT (3M Unitek TM, USA), whereas the other half was bonded with Transbond TM Plus Color Change (3M Unitek TM, USA). For each type of composite, the choice of method to remove the flash was determined by randomly distributing the teeth into the following subgroups: A (removal by naked eye, n = 10), B (removal with the aid of light head magnifying glass, under 4x magnification, n = 10), and C (removal with the aid of an operating microscope, under 40x magnification, n = 10). Brackets were debonded and teeth taken to a scanning electron microscope (SS-x-550, Shimadzu, Japan) for visualization of their buccal surface. Quantification of composite flash was performed with Image Pro Plus software, and values were compared by Kruskal-Wallis test and Dunn’s post-hoc test at 5% significance level. Results: Removal of pigmented orthodontic adhesive with the aid of light head magnifying glass proved, in general, to be advantageous in comparison to all other methods. Conclusion: There was no advantage in using Transbond TM Plus Color Change alone. Further studies are necessary to draw a more definitive conclusion in regards to the benefits of using an operating microscope. PMID:28125139

  7. Effect of moisture, saliva, and blood contamination on the shear bond strength of brackets bonded with a conventional bonding system and self-etched bonding system

    Science.gov (United States)

    Prasad, Mandava; Mohamed, Shamil; Nayak, Krishna; Shetty, Sharath Kumar; Talapaneni, Ashok Kumar

    2014-01-01

    Background: The success of bonding brackets to enamel with resin bonding systems is negatively affected by contamination with oral fluids such as blood and saliva. The new self-etch primer systems combine conditioning and priming agents into a single application, making the procedure more cost effective. Objective: The purpose of the study was to investigate the effect of moisture, saliva and blood contamination on shear bond strength of orthodontic brackets bonded with conventional bonding system and self-etch bonding system. Materials and Methods: Each system was examined under four enamel surface conditions (dry, water, saliva, and blood), and 80 human teeth were divided into two groups with four subgroups each of 10 according to enamel surface condition. Group 1 used conventional bonding system and Group 2 used self-etched bonding system. Subgroups 1a and 2a under dry enamel surface conditions; Subgroups 1b and 2b under moist enamel surface condition; Subgroups 3a and 3b under saliva enamel surface condition and Subgroup 4a and 4b under blood enamel surface condition. Brackets were bonded, and all the samples were then submitted to a shear bond test with a universal testing machine with a cross head speed of 1mm/sec. Results: The results showed that the contamination reduced the shear bond strength of all groups. In self-etch bonding system water and saliva had significantly higher bond strength when compared to other groups. Conclusion: It was concluded that the blood contamination showed lowest bond strength from both bonding systems. Self-etch bonding system resulted in higher bond strength than conventional bonding system under all conditions except the dry enamel surface. PMID:24678210

  8. A Comparison of the Shear Bond Strength of Orthodontic Brackets Bonded With Light-Emitting Diode and Halogen Light-Curing Units

    Directory of Open Access Journals (Sweden)

    SM. Abtahi

    2006-09-01

    Full Text Available Statement of the problem: Various methods such as light emitting diode (LED have been used to enhance the polymerization of resin-based orthodontic adhesives. There is a lack of information on the advantages and disadvantages of different light curing systems.Purpose: The aim of this study was to compare the effect of LED and halogen light curing systems on the shear bond strength of orthodontic brackets.Materials and Methods: Forty extracted human premolars were etched with 37% phosphoric acid and cleansed with water spray and air dried. The sealant was applied on the tooth surface and the brackets were bonded using Transbond adhesive (3M Unitek,Monrovia, Calif. Adhesives were cured for 40 and 20 seconds with halogen (Blue Light, APOZA, Taiwan and LED (Blue dent, Smart, Yugoslavia light-curing systems,respectively. Specimens were thermocycled 2500 times (from 5 to 55 °C and the shear bond strength of the adhesive system was evaluated with an Universal testing machine (Zwick GmbH, Ulm, Germany at a crosshead speed of 1 mm/min until the bracketswere detached from the tooth. Adhesive remnant index (ARI scores were determined after bracket failure. The data were submitted to statistical analysis, using Mann-Whitney analysis and t-test.Results: No significant difference was found in bond strength between the LED and halogen groups (P=0.12. A significant difference was not observed in the adhesive remnant index scores between the two groups (P=0.97.Conclusion: Within the limitations of this in vitro study, the shear bond strength of resin-based orthodontic adhesives cured with a LED was statistically equivalent to those cured with a conventional halogen-based unit. LED light-curing units can be suggested for the polymerization of orthodontic bonding adhesives.

  9. 偏心振捣搭设钢架平台的应用%Application of Eccentric Vibrating Erection of Steel Bracket Platform

    Institute of Scientific and Technical Information of China (English)

    方华美; 陈良

    2014-01-01

    Bored grouting pile , as basic treatment form , is widely used in water conservancy dike , coastal reclamation , inner river gate station and other engineering fields with rapid development of China ’ s water conservancy infrastructure construction .However , every aspect of construction process thereof must be strictly required since there are many factors affecting grouting pile construction .Steel bracket platform should be erected for replacing land construction especially aiming at some special locations incapable of direct land construction .Construction characteristics of water bored grouting pile are considered , and eccentric vibrating principle of eccentric vibrator is utilized .Using manual hoist assisting sinking to cooperate with the construction erection of steel bracket platform , thereby replacing previous construction of pressing steel pipes and erecting steel bracket platform by digging machine on the vessel , accelerating erection progress of steel bracket platform, saving cost, and reducing safety hidden danger .%随着我国水利基础设施建设的快速发展,钻孔灌注桩作为一种基础处理形式被广泛地应用于水利堤防、沿海围垦、内河闸站及其他工程领域。但由于影响灌注桩施工的因素很多,所以对其施工过程每一环节都必须严格要求,特别是针对某些无法直接陆地施工的特殊地段,需要搭设钢架平台代替陆地施工。结合水上钻孔灌注桩的施工特点,利用偏心振捣器的偏心振捣原理,用手动葫芦辅助下沉配合施工搭设钢架平台,代替了以往船上挖机压打钢管搭设钢架平台的施工,加快了钢架平台的搭设进度,节省了成本,减少了安全隐患。

  10. Formality in Brackets

    DEFF Research Database (Denmark)

    Garsten, Christina; Nyqvist, Anette

    suits’ (Nyqvist 2013), and of doing ‘ethnography by failure’ (Garsten 2013). In this paper, we explore the layers of informality and formality in our fieldwork experiences among financial investors and policy experts, and discuss how to ethnographically represent embodied fieldwork practices. How do we...

  11. Reconstructions of the axial muscle insertions in the occipital region of dinosaurs: evaluations of past hypotheses on marginocephalia and tyrannosauridae using the extant phylogenetic bracket approach.

    Science.gov (United States)

    Tsuihiji, Takanobu

    2010-08-01

    The insertions of the cervical axial musculature on the occiput in marginocephalian and tyrannosaurid dinosaurs have been reconstructed in several studies with a view to their functional implications. Most of the past reconstructions on marginocephalians, however, relied on the anatomy of just one clade of reptiles, Lepidosauria, and lack phylogenetic justification. In this study, these past reconstructions were evaluated using the Extant Phylogenetic Bracket approach based on the anatomy of various extant diapsids. Many muscle insertions reconstructed in this study were substantially different from those in the past studies, demonstrating the importance of phylogenetically justified inferences based on the conditions of Aves and Crocodylia for reconstructing the anatomy of non-avian dinosaurs. The present reconstructions show that axial muscle insertions were generally enlarged in derived marginocephalians, apparently correlated with expansion of their parietosquamosal shelf/frill. Several muscle insertions on the occiput in tyrannosaurids reconstructed in this study using the Extant Phylogenetic Bracket approach were also rather different from recent reconstructions based on the same, phylogenetic and parsimony-based method. Such differences are mainly due to differences in initial identifications of muscle insertion areas or different hypotheses on muscle homologies in extant diapsids. This result emphasizes the importance of accurate and detailed observations on the anatomy of extant animals as the basis for paleobiological inferences such as anatomical reconstructions and functional analyses.

  12. 电阻点焊电动机支架断裂失效分析%Fracture failure analysis of resistance spot welding motor bracket

    Institute of Scientific and Technical Information of China (English)

    王亚婷; 徐越兰; 刘敏; 李文健

    2011-01-01

    分析了电阻点焊电动机支架高频振动破坏试样的失效原因.通过焊材成分分析、断口形貌分析和微观金相组织分析,结果表明,固定电动机支架发生断裂的原因是由于焊接工艺不当所致.因此在焊接过程中应该适当改变焊接工艺参数,调整焊接规范.%Fracture failure analysis was made on resistance spot welding motor bracket test specimens which were destroyed by the high-frequency vibration.Component analysis of weld materials, macroscopic analysis of fracture morphology and microscopic analysis of the microstructure show that the reason why the fixed motor bracket was broken was due to improper welding.Therefore, during the welding process the welding parameters should be changed appropriately, and the welding conditions should be adjusted too.

  13. Dynamic Simulation of Torsion Beam Bracket%扭力梁安装支座动力学仿真分析

    Institute of Scientific and Technical Information of China (English)

    王亚南; 宋纪侠; 王彦

    2012-01-01

    In the paper,some torsion beam bracket is simulated with the help of dynamics software Adams/ride and Adams/car.According to contrast,we can conclude that the analysis result of torsion beam bracket in rear suspension assembly Adams/car is the same as that in whole vehicle Adams/ride.And then rear suspension assembly is simulated under different work conditions,and then the main cause of carling outrigger breakage is found out.%运用Adams/ride和Adams/car软件对某车型扭力梁安装支座进行动力学仿真分析。对比分析可知,运用Adams/car对后悬架系统进行扭力梁安装支座的受力分析基本能够模拟其在整车状态下Adams/ride的受力分析。进而对后悬架系统在不同工况下进行受力分析,找出纵梁舷外支架开裂的主要原因。

  14. Comparison of periodontal condition between conventional and self-ligating brackets%自锁托槽与传统托槽矫治器对牙周健康影响的比较研究

    Institute of Scientific and Technical Information of China (English)

    张丽雯; 徐宝华; 周于翔; 武冠英

    2010-01-01

    目的 对比戴用自锁托槽与传统托槽矫治器后牙周指数的变化.材料和方法选取12~18岁正畸患者80例,按矫治器类型分为两组:实验组,40例采用AO公司生产的T3自锁托槽矫正的患者;对照组,采用杭州西湖公司生产的徐氏托槽矫正的患者40例.由同一牙周专科医师分别检测80例患者治疗前和治疗6个月的各项牙周指数(GI,PLI,SBI,PD).结果 治疗6个月后两组间牙周指数(GI,PLI,SBI,PD)差异无显著性.结论 自锁托槽矫治器不会更有利于牙周组织的健康,牙周的健康状况取决于患者的口腔卫生状况.%Objective To compare the periodontal indices between the use of self-ligating brackets and conventional pre-adjusted brackets. Methods Eighty patients (12 to 18 years old) were divided into 2 groups (group A: 40 patients with self-ligating brackets and group B: 40 patients with conventional pre-adjusted brackets). Periodontal indices (GI, PLI, SBI and PD) were examined in both groups. Results No difference was found in the indices recorded between the two groups after 6months of treatment. Conclusions Self-ligating brackets did not have an advantage over conventional brackets with respect to the periodontal status.

  15. Clinical comparison between a resin-reinforced self-cured glass ionomer cement and a composite resin for direct bonding of orthodontic brackets. Part 2: Bonding on dry enamel and on enamel soaked with saliva.

    Science.gov (United States)

    Cacciafesta, V; Bosch, C; Melsen, B

    1999-11-01

    The purposes of this investigation were to compare the clinical performance of a resin-reinforced self-cured glass ionomer cement to a standard composite resin in the direct bonding of orthodontic brackets when bonded onto: a) dry teeth and b) teeth soaked with saliva. The two bonding agents were compared using a split-mouth design. In that, both systems were used for direct bonding of stainless steel brackets in every patient. Thirty-eight consecutive patients with fixed appliances were followed for a period of 12 months. The patients were randomly divided into two groups: group A (11 patients) and group B (27 patients). In group A, the performance of 220 stainless steel brackets was evaluated: 110 brackets were bonded with GC Fuji Ortho glass ionomer cement (GC Industrial Co., Tokyo, Japan) onto dry teeth, and 110 bonded with System 1+ composite resin (Ormco Corp., Glendora, CA). In group B, the performance of 540 stainless steel brackets was evaluated: 270 brackets were bonded with GC Fuji Ortho onto teeth soaked with saliva, and 270 bonded with System 1+. In group A, GC Fuji Ortho recorded an overall failure rate (34.5%) significantly higher (p 0.05) between the failure rates of the two bonding agents were found when GC Fuji Ortho was used on teeth soaked with saliva. It was concluded, therefore, that GC Fuji Ortho shows clinically acceptable bond strengths when bonded onto moist teeth, but not when used on dry enamel. Both bonding agents failed mostly at the enamel/adhesive interface, without causing any enamel damage.

  16. Estudo comparativo da resistência adesiva da interface resina/braquete, sob esforços de cisalhamento, empregando três resinas compostas e três tipos de tratamento na base do braquete Comparative study of the shear bond strength of the resin/bracket interface, using three different resin composites and three different treatments in the base of the bracket

    Directory of Open Access Journals (Sweden)

    Adriano Lia Mondelli

    2007-06-01

    , associado ou não ao jateamento com óxido de alumínio, houve uma queda dos valores de resistência ao cisalhamento. O tratamento com jateamento de óxido de alumínio na base dos braquetes melhorou todos os valores de adesividade para todos os materiais de colagem utilizados nesta pesquisa.AIM: Considering that the adhesion between the brackets and the resin is chemo-mechanical, the aim of this study was to investigate: 1 the efficacy of the method used to assess the bond strength at the resin/bracket interface; 2 the shear bond strength of the resin/bracket interface using three resin composites (Concise orthodontic, Transbond XT and Filtek Z-250; 3 the effect of sandblasting of the base of the metallic bracket with aluminum oxide, associated or not to the application of adhesive. METHODS: Shear bond strength was carried out at a universal testing machine. Data were submitted to analysis of variance and Tukey multiple comparison test. RESULS AND CONCLUSIONS: The occurrence of 12.5% of cohesive failures may be considered minimal, thus indicating that the method is appropriate to assess the bond strength at the resin/bracket interface. The different resin composites (Concise Orthodontic, Transbond XT and Filtek Z-250 used for bonding without any previous surface treatment of the bracket (control groups resulted in similar shear bond strength. The application of adhesive, with or without previous sandblasting of the base of the bracket, improved the shear bond strength for the Concise orthodontic resin composite, when compared to its control group. Sandblasting of the bracket, regardless of the combined use of adhesive, was statistically superior for the Transbond XT resin composite when compared to its control group. The application of the adhesive Single Bond in the base of the bracket, with or without previous sandblasting, promoted a decrease in the shear bond strength for the Filtek Z-250 resin composite. Sandblasting of the metallic bracket with aluminum oxide

  17. 城市客车油箱托架结构有限元分析与优化设计%Finite Element Analysis and Optimal Design on Fuel Tank Bracket Structure for City Bus

    Institute of Scientific and Technical Information of China (English)

    徐军; 管义群

    2014-01-01

    The authors use FEM to analyse the fuel tank bracket structure of JS6106GHA city bus, find the faults, optimize its structure, improve its reliability, and offer advice for the structure design of the bus fuel tank bracket.%对JS6106GHA城市客车的油箱托架结构进行有限元分析,找出缺陷,进行优化改进,以提高其可靠性,从而为合理地设计客车油箱托架结构提供参考。

  18. Shear strength of orthodontic bracket bonding with GIC bonding agent after the application of CPP-ACPF paste

    Directory of Open Access Journals (Sweden)

    Melisa Budipramana

    2013-03-01

    Full Text Available Background: White spot lesion is a major problem during fixed orthodontic treatment. This problem can be solved by minimizing white spot lesion before the treatment and using a fluoride-releasing bonding agent. The application of casein phosphopeptidesamorphous calcium phospate fluoride (CPP-ACPF paste as remineralization agent before treatment and GIC as orthodontic bonding agent is expected to overcome this problem as well as to strengthen GIC bonding. Purpose: To measure the shear strength of fix orthodontic appliance using GIC bonding with CPP-ACPF application prior treatment. Methods: In this study, 50 extracted premolars were randomly divided into 2 groups: group 1 as treatment group and group II as control group that was not given CPPACPF pretreatment. After having been cut and put into acrylic device, the samples in group I were given pretreatment with CPP-ACPF paste on enamel surface for 2 minutes twice a day as instructed in product label for 14 days. Orthodontic brackets were bonded with GIC bonding agent on all samples in both groups as instructed in product label. Then, the shear strength was measured by Autograph Shimatzu with crosshead speed 0.5 mm/minute. The data was analyzed with Independent t-test. Results: The mean shear bond strength in treatment group was 19.22 ± 4.04 MPa and in control group was 12.97 ± 3.97 MPa. Independent t-test analysis showed that there was a significant difference between treatment and control group (p<0.05. Conclusion: CPP-ACPF pretreatment could increase GIC orthodontic bonding shear strength.Latar belakang: Lesi putih karies merupakan masalah utama selama perawatan dengan peranti cekat ortodonti. Hal ini dapat diatasi dengan cara mengurangi lesi putih sebelum perawatan dengan menggunakan bahan bonding yang mengandung fluorida. Aplikasi pasta casein phosphopeptides-amorphous calcium phospate fluoride (CPP-ACPF sebagai bahan remineralisasi sebelum perawatan dan bahan bonding GIC diharapkan dapat

  19. Substitution of argon in the ladle metallurgy process; Analise da substituicao do argonio nos processos de metalurgia de panela

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Aldo H.A.; Ribeiro, Helber L.O.; Santos, Antonio G. dos [USIMINAS, Ipatinga, MG (Brazil). Centro de Pesquisas

    1990-12-31

    Industrial trials were carried out by bubbling nitrogen in place of argon into Al-killed and Al-Si killed steels in the ladle. Results confirmed the theoretical data based on kinetic studies that specified nitrogen levels can be obtained in the steel without impairing product quality. (author). 8 refs., 3 tabs., 6 figs.

  20. On the uniqueness of the (2,2-dimensional supertorus associated to a nontrivial representation of its underlying 2-torus, and having nontrivial odd brackets

    Directory of Open Access Journals (Sweden)

    R. Peniche

    2004-01-01

    Full Text Available It is proved that up to isomorphism there is only one (2,2-dimensional supertorus associated to a nontrivial representation of its underlying 2-torus, and that it has nontrivial odd brackets. This supertorus is obtained by finding out first a canonical form for its Lie superalgebra, and then using Lie's technique to represent it faithfully as supervector fields on a supermanifold. Those supervector fields can be integrated, and through their various integral flows the composition law for the supergroup is straightforwardly deduced. It turns out that this supertorus is precisely the supergroup described by Guhr (1993 following a formal analogy with the classical unitary group U(2 but with no further intrinsic characterization.

  1. Class III malocclusion with complex problems of lateral open bite and severe crowding successfully treated with miniscrew anchorage and lingual orthodontic brackets.

    Science.gov (United States)

    Yanagita, Takeshi; Kuroda, Shingo; Takano-Yamamoto, Teruko; Yamashiro, Takashi

    2011-05-01

    In this article, we report the successful use of miniscrews in a patient with an Angle Class III malocclusion, lateral open bite, midline deviation, and severe crowding. Simultaneously resolving such problems with conventional Class III treatment is difficult. In this case, the treatment procedure was even more challenging because the patient preferred to have lingual brackets on the maxillary teeth. As a result, miniscrews were used to facilitate significant asymmetric tooth movement in the posterior and downward directions; this contributed to the camouflage of the skeletal mandibular protrusion together with complete resolution of the severe crowding and lateral open bite. Analysis of the jaw motion showed that irregularities in chewing movement were also resolved, and a stable occlusion was achieved. Improvements in the facial profile and dental arches remained stable at the 18-month follow-up.

  2. Resistência ao cisalhamento de braquetes metálicos utilizando sistema adesivo autocondicionante Shear bond strength evaluation of metallic brackets using self-etching system

    Directory of Open Access Journals (Sweden)

    Camilo Aquino Melgaço

    2011-08-01

    Full Text Available OBJETIVO: avaliar a resistência ao cisalhamento de braquetes metálicos colados com sistema autocondicionante utilizado imediatamente e após 2, 5 e 9 dias depois da ativação e armazenagem. MÉTODOS: utilizaram-se 64 dentes bovinos divididos igualmente em quatro grupos e devidamente preparados para receber a colagem dos braquetes. Em T1, realizou-se a ativação de 7 blisters de adesivos autocondicionantes (de acordo com as normas do fabricante e procedeu-se à colagem imediata apenas dos braquetes do grupo I. Os adesivos ativados foram, então, armazenados à temperatura de 4ºC e reutilizados em períodos de 2 dias (T2, 5 dias (T3 e 9 dias (T4 para a colagem dos braquetes dos grupos II, III e IV, respectivamente. RESULTADOS: não se observou diferença estatística quando comparados os valores médios de tensão para resistência ao cisalhamento entre os grupos I, II e III. Entretanto, diferença estatística foi encontrada quando esses valores foram comparados aos do grupo IV. CONCLUSÃO: o armazenamento do adesivo autocondicionante depois de ativado, à temperatura média de 4ºC, por até 5 dias, parece não afetar os resultados quanto às tensões de resistência ao cisalhamento; novos estudos são necessários para avaliação das demais características do material quando de sua utilização por período de tempo prolongado após sua ativação.OBJECTIVE: To evaluate the shear bond strength of metallic brackets using the self-etching system after its activation and storage for 2, 5 and 9 day periods. METHODS: A total of 64 bovine teeth were divided in four groups and prepared to receive the brackets. Initially, seven self-etching primer blisters were activated and used to bond the brackets of group I. The blisters were store at a constant temperature of 4ºC for 2, 5 and 9 days and used to bond the brackets of groups II, III and IV, respectively. RESULTS: No statistic difference was found in shear bond strength comparing groups I, II

  3. A comparative study of self-ligating brackets frictional resistances during the orthodontic space closure%自锁托槽对关闭拔牙间隙阶段滑动阻力的影响

    Institute of Scientific and Technical Information of China (English)

    吴红; 曲虹

    2015-01-01

    Objective To compare the frictional resistance (FR) of two different self-ligating brackets and conventional brackets coupled with the stainless steel archwire during the space closure phase in the orthodontic treatment. Methods The patients with severe crowding malocclusion were treated by two different self-ligating brackets (Damon®,Tomy®) and conventional brackets ligating by elastometric modules and stainless steel ligating wires of size 0.019×0.025 inch.The static and kinetic frictional resistance of each bracket-archwire system was ex-amined in the dry state during the orthodontic space closure phase, and analyzed by ANOVA. Results During the space closure phase, there were significantly differences in these different bracket-archwire systems (P<0.01), and the frictional resistance was as follows:Damon® groupbrackets was significantly lower than that of the conventional bracket during the orthodontic space closure phase, and the frictional resistance of the passive self-ligating bracket was significantly lower than the active self-ligating bracket.%目的:比较在牙齿关闭拔牙间隙过程中不同自锁托槽和传统托槽与不锈钢丝组合所产生的滑动阻力。方法在干燥环境下,分别选择2种自锁托槽(被动Damon®和主动Tomy®)和传统托槽的2种结扎方式(橡皮结扎圈和结扎丝)与0.019×0.025英寸不锈钢丝组合,测量严重牙列拥挤患者在拔牙后排齐整平的下颌模型上关闭拔牙间隙阶段的滑动阻力。采用方差分析的方法对各项测量数据进行统计学处理。结果在关闭拔牙间隙阶段,不同托槽组合、组间的滑动阻力的差异均具有显著的统计学意义(P<0.01),最大静摩擦力和滑动摩擦力由小到大依次为被动Damon组<主动Tomy组<结扎丝结扎组<结扎圈结扎组。结论在关闭拔牙间

  4. Comparison of the effect of hydrogel and solution forms of sodium ascorbate on orthodontic bracket-enamel shear bond strength immediately after bleaching: An in vitro study

    Directory of Open Access Journals (Sweden)

    Kimyai Soodabeh

    2010-01-01

    Full Text Available Aim: This study compared the effects of hydrogel and solution forms of sodium ascorbate (SA with two different application times on bracket bond strength subsequent to bleaching. Materials and Methods: A total of 72 sound premolars were randomly divided into six groups (n = 12: An unbleached control group (group one and five experimental groups of carbamide peroxide. Specimens in group two were bonded immediately after bleaching; specimens in groups three and four were bleached, then treated with SA solution for ten minutes and three hours, respectively, and then bonded. In groups five and six, SA hydrogel was used and the specimens were prepared similar to groups three and four, respectively. Following debonding, bond strengths were recorded in MPa. To evaluate the amount of resin left on the enamel surfaces, adhesive remnant index (ARI scores were used. Statistical Analysis: The bond strength data were analyzed with ANOVA and pairwise comparisons were made by Tukey test. The ARI data were subjected to Kruskal-Wallis test and two-by-two comparisons were made by the Mann-Whitney U test. Results: There were significant differences in bond strengths between the groups ( P < 0.0005. However, the differences between groups three, four, five and six were not significant. Furthermore, there were no significant differences between group one and groups four and six, whereas the differences between the other groups were significant ( P < 0.05. Regarding ARI, there were significant differences among the groups ( P = 0.004. Conclusion: Bleaching significantly decreased the bracket bond strength. Compromised bonding was reversed with a three-hour application of both forms of SA.

  5. THE ANALYSIS OF THE INFLUENCE OF THE CHARACTERISTICS OF SUSPENSION BRACKET AND TIRES ON LOADING OF WHEELS OF THE CAR WHEN MOVING ON A MULCH BACKGROUND

    Directory of Open Access Journals (Sweden)

    Oberemok V. A.

    2015-05-01

    Full Text Available The existing settlement modes of loading of wheels of cars are defined for the conditions which are closest to road service conditions and are reflected in the existing standards. However these standards can't be applied to an assessment of functional qualities of systems of cushioning the cars which are operated in the conditions of agricultural production. The small step of roughnesses, change the cushioned characteristics under the influence of operational factors lead to emergence of the off-design modes of the movement. The purpose of the work was the research of loading of wheels of the car when moving on mulch of grains. For the purpose of obtaining characteristics of the roughnesses influencing car wheels we have recorded a smoothed microprofile of the field and got the statistics, rated autocorrelated function, spectral density of influence of a microprofile. For carrying out the researches the known mathematical model of a car road system was accepted. Influence of speed of the movement, normal rigidity of springs and tires, coefficients of damping of a suspension bracket and tires on vertical fluctuations and loading of wheels of forward and back axes of the car is investigated. The executed researches showed that the movement of the car is followed by fluctuations of indicators of loading of running system with obviously expressed periodic components. The change of the coefficient of damping of a passive suspension bracket and tires in possible limits has no essential impact on loading of wheels. Values of normal roughness of springs of forward and back axes of the car, normal rigidity of tires at which dynamic load of wheels of the car is minimum are established

  6. Comparison of Shear Bond Strength of Orthodontic Brackets Bonded to Enamel Prepared By Er:YAG Laser and Conven-tional Acid-Etching

    Directory of Open Access Journals (Sweden)

    M.H. Hosseini

    2012-01-01

    Full Text Available Introduction: The purpose of this study was to compare shear bond strength (SBS of orthodontic brackets bonded to enamel prepared by Er:YAG laser with two different powers and conventional acid-etching.Materials and Methods: Forty-five human premolars extracted for orthodontic purposes were randomly assigned to three groups based on conditioning method: Group 1- conventional etching with 37% phosphoric acid; Group 2- irradiation with Er:YAG laser at 1 W; and Group 3- irradiation with Er:YAG laser at 1.5 W. Metal brackets were bonded on prepared enamel using a light-cured composite. All groups were subjected to thermocycling process. Then, the specimens mounted in auto-cure acryle and shear bond strength were measured using a universal testing machine with a crosshead speed of 0.5 mm per second. After debonding, the amount of resin remaining on the teeth was determined using the adhesive remnant index (ARI scored 1 to 5. One-way analysis of variance was used to compare shear bond strengths and the Kruskal-Wallis test was performed to evaluate differences in the ARI for different etching types.Results: The mean and standard deviation of conventional acid-etch group, 1W laser group and 1.5W laser group was 3.82 ± 1.16, 6.97 ± 3.64 and 6.93 ± 4.87, respectively.Conclusion: The mean SBS obtained with an Er:YAG laser operated at 1W or 1.5W is approximately similar to that of conventional etching. However, the high variability of values in bond strength of irradiated enamel should be considered to find the appropriate parameters for applying Er:YAG laser as a favorable alternative for surface conditioning.

  7. Preparation of customized typodont model in labial and lingual brackets system%简易个性化唇舌侧矫治技术Typodont模型的制作

    Institute of Scientific and Technical Information of China (English)

    方志欣; 周嫣; 陈世稳; 黄敏方

    2015-01-01

    Objective To investigate a simpler method of preparation of customized typodont model in labial and lingual brackets system. Methods Explored a simpler and more precise method of preparation of customized typodont model in labial and lingual brackets system used in the further study of orthodontic mechanics through several test procedures,such as simulating set-up,bonding the labial and lingual brackets,preparing impression with silicon rubber and pouring the typodont models. ResuIts The negative forms suit for preparation of customized typodont model used in comparative research of orthodontic mechanics in labial and lingual brackets system were obtained and the typodont model were made repeatedly. ConcIusion The artificial teeth are very stable in the negative forms and the typodont models can be poured accurately and repeatedly,and be a platform for further comparative research of orthodontic mechanics in labial and lingual brackets system.%目的:探索一种简易个性化唇舌侧矫治技术Typodont模型的制作方法.方法:通过模拟排牙,粘结唇舌侧托槽,制备硅橡胶阴模,灌制Typodont模型等步骤的实验,探索简易且精确的适用于唇舌侧矫治技术矫治力学对比分析研究的Typodont模型的制作方法.结果:获得了适用于唇舌侧矫治技术矫治力学对比分析研究的Typodont模型阴模并多次灌制出其Typodont模型.结论:该方法人工牙在阴模中稳定性好,可多次精确灌制Typodont模型,为后续的力学研究打下了基础.

  8. Comparision of bracket transfer accuracy of indirect bonding methods%间接粘结中托槽转移精确度的比较

    Institute of Scientific and Technical Information of China (English)

    刘浩; 王鹏来; 王海岚; 张婷

    2016-01-01

    目的 比较间接粘结技术中使用两种不同转移托盘及不同牙列拥挤度时的托槽转移精确度.方法 收集30名患者的上颌或下颌硬石膏模型,各取2付,在之后的托槽转移步骤中根据用单层膜片和双层膜片制作间接粘结的转移托盘,分为A、B两组;根据其牙列拥挤度、1为轻度及以下拥挤,2为中度拥挤,再分为A1、A2、B1、B2组,每组中各有15付模型.模型上粘结托槽后经CBCT扫描并重建数字化三维模型,分别用单层膜片(A1、A2组)和双层膜片(B1、B2组)制作间接粘结的转移托盘,将转移托盘重新放回初始模型完成托槽粘结,再次经过CBCT扫描并重建数字化三维模型,通过Geomagic软件比对前后的数字模型,比较托槽位置在转移过程中的变化程度.结果 托槽转移前后的最大距离及平均距离各组之间无统计学差异(P>0.05),B组平均距离的标准差大于A组,且差异有统计学意义(P<0.05).B2组平均距离的标准差大于A1、A2、B1组,差异有统计学意义(P<0.05).结论 使用单层膜片和双层膜片的间接粘结技术托槽转移精确度无显著差异,单层膜片的稳定性更佳;牙列拥挤度增大会使托槽转移的稳定性下降.%Objective To compare bracket transfer accuracy of indirect bonding method using two different transfer trays with different dental crowding conditions.Methods Casts of 30 patients were collected.Each casts was impressed twice and the casts were grouped into A and B.According to crowding degrees,casts were grouped into A1,A2,B1 and B2 (n =15).A1 and B1 were mild crowding groups,while A2 and B2 were moderate crowding groups.Casts with brackets were scanned using CBCT and 3D reconstructed using Mimics software.Indirect bonding transfer trays for group A and B were made with one-layer film and bilayer films,separately.Transfer trays were put on to initial casts to complete bonding.Casts were scanned and 3D reconstructed again using CBCT and

  9. DESIGN AND REALISATION OF MODELLING AND FINITE ELEMENT DIVISION ON SHIP FLANGED BRACKET%船舶折边肘板建模与有限元划分的设计与实现

    Institute of Scientific and Technical Information of China (English)

    许一敏; 冷文浩; 周炜; 田志峰; 程成

    2013-01-01

    Bracket is a common component for connection in ship structure and other steel structures,and flanged bracket is frequently used in flanged docking for main ship components.In order to enhance the efficiency of modelling flanged bracket,we design the parametric 3D solid modelling process for flanged bracket.According to the modelling process,we discuss the methods of parametric bracket contour generation and flanges information storage,provide the algorithms for coordinate transformation and flange rotation,and study the objectoriented programming and finite element method.Moreover,we import MSC.Patran for mesh division,realise the transformation from CAD model to finite element analysis model,and present PDM integration.Taking AutoCAD as the development platform,VS.Net as the programming environment,and ObjectARX as the development tool,we implement the object-oriented parametric solid modelling system for flanged bracket.%肘板是船舶结构及其它钢结构中常用的连接构件,折边肘板经常用于船舶主构件的折边对接中.为了提高折边肘板建模的效率,设计折边肘板参数化三维实体造型过程;根据造型过程,探讨肘板轮廓参数化生成及折边信息存储方法;给出坐标转换及折边旋转算法;研究面向对象与有限元方法;并导入MSC.Patran进行网格划分,实现CAD模型到有限元分析模型的转化;给出PDM的集成:以AutoCAD为开发平台,VS.Net为编程环境,ObiectARX为开发工具,实现了面向对象的折边肘板参数化实体造型.

  10. Study on bonding strength of nitrogen-doped TiO2-xNx films to orthodontic brackets%掺氮TiO2-xNx薄膜托槽粘接强度的研究

    Institute of Scientific and Technical Information of China (English)

    王璞; 曹宝成; 王婧; 曹帅; 高静; 王育华

    2012-01-01

    目的 研究掺氮TiO2-xNx薄膜托槽的制备过程对粘接强度的影响.方法 应用磁控溅射法在普通金属托槽表面制备TiO2-xNx薄膜得到掺氮TiO2-xNx薄膜托槽,将掺氮TiO2-xNx薄膜托槽通入氮气后在450℃条件下退火处理2h得到退火后掺氮TiO2-xNx薄膜托槽.通过X射线衍射观察普通金属托槽及退火前、退火后掺氮TiO2-xNx薄膜托槽表面结构,通过扫描电镜(SEM)观察3种托槽网底形貌.将60颗因正畸需要已拔除的健康前磨牙按照3种托槽和2种储存条件(室温蒸馏水、冷热循环)随机分为6组,每组10颗,使用京津釉质粘合剂按要求粘接,用电子万能材料试验机测试并记录所有托槽的剪切强度,使用SPSS 17.0统计软件处理数据,并对实验结果进行单因素方差分析.结果 掺氮TiO2-xNx薄膜托槽表面为均一的锐钛矿相结构,晶粒粒径为30 nm.3种托槽的底板网格清晰,排列整齐,无明显不同.冷热循环条件下的3种托槽粘接强度均低于室温蒸馏水保存下的托槽粘接强度(P<0.01),同一处理条件下3种托槽的粘接强度差异无统计学意义(P>0.05).结论 掺氮TiO2-xNx薄膜托槽的粘接强度没有受到制备过程的影响,能够满足临床正畸治疗需要.%Objective To evaluate the effect of preparation process on the bonding strength of the nitrogen-doped TiO2-xNx films on brackets. Methods Radio frequency magnetron sputtering was used to prepare nitrogen-doped TiO2-xNx films on the surface of stainless steel brackets. Post annealing was performed on TiC>2-x Nx films at 450'C in nitrogen atmosphere for 2 h. The structures and surface morphologies of 3 types brackets, ordinary stainless steel brackets, nitrogen-doped TiO2-xNx films on brackets before annealing and the brackets after annealing, were evaluated by X-ray diffraction. The base plate of brackets was observed by scanning electron microscopy (SEM). The three types of brackets were also divided into 2 groups

  11. New Technology of Case Bracket Guide Rail Film Bonding Process%机箱托架导轨胶膜粘接新工艺技术

    Institute of Scientific and Technical Information of China (English)

    喻少英; 何燕春

    2014-01-01

    对机箱托架导轨的材料选用聚四氟乙烯软带,粘接采用胶膜粘接工艺进行了全面研究,确定了胶膜粘接热压工艺参数:热压温度130~140℃,时间15~20min,压力3~4kg/cm2。对胶膜粘接工艺(新工艺)和胶黏剂粘接工艺(老工艺)进行了比较,结果表明:选用的胶膜粘接工艺参数合理,在最佳工艺参数条件下,胶膜粘接的剥离强度是胶黏剂粘接强度的1.5倍以上,工艺周期同胶黏剂粘接周期相比,缩短了70%以上,满足机箱托架导轨粘接要求,因此胶膜粘接工艺是托架导轨粘接首选。%A comprehensive study on using PTFE soft belt as the material of case bracket guide rail and the adhesive film bonding process as the bonding technology is carried out. And the hot pressing process parameters of adhesive film bonding are confirmed as follows:the hot pressing temper-ature, time and pressure is 130~140℃, 15~20min and 3~4kg/cm2 respectively. The adhesive film bonding process (new technology) and adhesive bonding process (old technology) are compared, the results showed that under the optimum process parameters, the peel strength of adhesive film bonding process is at least 1.5 times than that of adhesive bonding, and its cycle time reduces more than 70%. The adhesive film bonding process can meet the requirements of case bracket guide rail bonding;therefore it is the preferred choice.

  12. 制备TiO2-xNx薄膜陶瓷托槽的抗菌性能%TiO2-xNx thin filmson ceramic bracket surfaces:preparation and antibiotic performance

    Institute of Scientific and Technical Information of China (English)

    王建卫; 王宇; 车远倩; 朱博武; 曹宝成

    2016-01-01

      结果与结论:①TiO2-xNx薄膜为锐钛矿型,结构均匀致密,随着薄膜厚度的增加,X射线衍射峰表现为增强趋势;②厚度最高薄膜最终附着力为18.37 N,说明薄膜与托槽具有较好的附着力,可承受在口腔应用中所受到的摩擦;③镀膜后,厚度最高薄膜托槽的色泽均有所变化,但变化较小,不至于影响陶瓷托槽原有的美观特性;④TiO2-xNx薄膜陶瓷托槽对白色念珠菌、变形链球菌均有一定的抗菌性能,且随着薄膜厚度的增加抗菌性能逐渐增强,对变形链球菌的抗菌效果更明显;⑤结果表明,TiO2-xNx薄膜陶瓷托槽在不影响美观的同时,对常见口腔致龋菌和条件致病菌具有较高的抗菌作用,且与托槽具有较好的附着力。%BACKGROUND:Enamel demineralization has been plaguing doctors and patients in the fixed orthodontic treatment, so we attempt to seek an effective method of reducingitsincidence. OBJECTIVE:To prepare TiO2-xNx thin filmsat different thicknesses on the ceramic bracket surface by sol-gel method folowed by detection of antibiotic performance. METHODS:TiO2-xNx thin films at different thicknesses were prepared on the ceramic bracket surface by sol-gel method. The crystal structure, surface morphology and attachment force of these thin films were analyzed by X-ray diffraction, scanning electron microscope and multi-function material surface tester, respectively. The color changes of ceramic brackets before and after coating were evaluated through German VITA Easyshade Advance 4.0 photoelectric color comparator. Antibiotic performance of the ceramic bracket coated with TiO2-xNx thin film forCandida albicansandStreptococcus mutanswas evaluated by the flat colony counting method. RESULTS AND CONCLUSION:The prepared TiO2-xNx thin film was anatase type, which had uniform and compact structure, and its X-ray diffraction peaks were elevated with the increase of film thickness. The

  13. 超高墩、跨河边跨支架设计与施工技术%Design and Construction Technology of Cross Bracket with Super High Pier and Cross the River

    Institute of Scientific and Technical Information of China (English)

    占波

    2014-01-01

    本文主要介绍了沈丹客运专线连续梁边跨现浇段的设计与施工技术。通过理论设计计算与现场实践考验,该支架使用效果较好,对高墩支架施工具有参考价值。%This paper mainly introduces the design and constr- uction technology of continuous beam side span cast-in-place section of Shenyang-Dandong passenger dedicated line. Thro- ugh theoretical calculation and field test of the design practice, the bracket has good using effect, which has reference value for the construction of high pier bracket.

  14. Design of the Spining Bracket with Electromagnetic Riveter based on Ergonomic Analysis%基于人机工程分析的手持式电磁铆枪旋转托架设计

    Institute of Scientific and Technical Information of China (English)

    张喆; 曹增强; 陈琦

    2013-01-01

    It analyzed the existing problem of the traditional gantry bracket with electromagnetic riveter which only can be used for plate-shaped product. For the purpose of solving the existing problem, a new spining bracket was introduced based on the gantry bracket. Structure design and the analysis of the kinetic characteristic was completed. The 3D modeling of the mechanical parts and the virtual assembly simulation was finished based on CATIA. Through the ergonomic analysis of DELMIA, it analyzed the operation space and verified the design parameters as well as the simulation of collision interference was done. The results indicate that the spining bracket can meet the design requirements and solve the riveting problem of the arc-shaped product%分析了传统悬挂铆枪的托架只适用于平板状结构产品铆接等问题.为解决此问题,在龙门式托架的基础上提出了新型旋转托架,进行了结构设计并分析了其运动特点,建立了基于CATIA的三维零件模型,进行了虚拟装配,并基于DELMIA分析了托架人机工程的近身作业空间,进行旋转托架的碰撞干涉检查,验证了其初始的设计参数.结果表明旋转托架满足了设计要求,并且可以实现圆弧形结构产品的铆接,基于人机工程的设计方法编短了开发周期,降低了设计成本.

  15. Variação da curvatura da base de braquetes "Straight-Wire": estudo comparativo entre quatro marcas comerciais Straight-wire base brackets curvature: analysis of four differents manufactures

    Directory of Open Access Journals (Sweden)

    Luciana de Paula Gontijo

    2004-06-01

    Full Text Available Este trabalho objetivou avaliar as qualidades arquiteturais das bases dos braquetes "Straight-Wire" de quatro marcas comerciais (Morelli, Abzil Lancer, Unitek e A-Company comparando as suas curvaturas médias no sentido oclusogengival e mesiodistal. As curvaturas das bases dos braquetes foram medidas por meio de uma máquina de medidas universais da Société Genevoise D' Instruments de Physique, marca CSIP, modelo MUL-300, e os dados encontrados foram transferidos para um software de desenho AutoCAD 2000, gerando superfícies em ambiente tridimensional, a partir das quais se mediu a curvatura e o raio das bases dos acessórios ortodônticos. Os resultados demonstraram que a curvatura da base de cada braquete variou em sua extensão e que para um mesmo elemento dentário, as curvaturas e seus respectivos raios variaram entre as marcas comerciais analisadas.The objective of this study was to determine the average occlusogingival and mesiodistal curvature of the bases of straight-wire brackets. Brackets from four different manufactures were utilized: Morelli, Abzil Lancer, Unitek and A-Company. The measurements of the curvature of the bases of the brackets were, initially, taken with a universal instrument of the Société Genevoise D'Instruments de Physique, known as CSIP, model MUL-300. The data obtained was transferred to an AUTOCAD 2000 software, which generated a three dimensional image, where the curvature and the radius of the bases were finally measured. The results demonstrated a great variability of these measurements among the four different brands for the same bracket.

  16. 脉冲激光辅助去除正畸金属托槽方法初探%Pulsed Nd:YAG laser-aided debonding for removing the metal brackets

    Institute of Scientific and Technical Information of China (English)

    赖仁发; 王海云; 陈铁; 刘湘宁

    2010-01-01

    Objective To explore the possibility of pulsed Nd:YAG laser-aided debonding for removing orthodontic metal brackets and to compare the method with the conventional mechanical debonding method.Methods Fifty healthy premolars extracted for orthodontic purpose were randomly divided into five groups (10 teeth in each group).There were four experimental groups and one control group.Every tooth was bonded with bracket.Laser was used to irradiate the teeth in experimental groups with different electric currents(13.0,13.5,14.0,14.5 A).During the irradiation,the brackets received 4.9 N of force until the brackets off.The time needed for debonding and the temperature change of the pulp cavity were recorded.The teeth in control group were debonded using mechanical method.The adhesive remnant index (ARI) was calculated using stereomicroscope and imagetool software.All samples were examined with a scanning electron microscope.Results The time taken between the four groups were (67.70±7.18),(35.90±4.28),(24.90±3.76),(6.90±2.33) s,highly statistical difference was found in the time needed for debonding(P0.05).扫描电镜下可见对照组釉面横纹已被破坏,釉质表面粗糙不平;实验组釉质表面清洁,未见划痕、弹坑样及蜂窝样改变.结论 脉冲Nd:YAG激光辅助去除正畸金属托槽是一种可行的方法;与机械法相比,脉冲Nd:YAG激光辅助去除托槽及粘接剂的过程不破坏釉质表面结构.

  17. Highly antibacterial activity of N-doped TiO2 thin films coated on stainless steel brackets under visible light irradiation

    Science.gov (United States)

    Cao, Shuai; Liu, Bo; Fan, Lingying; Yue, Ziqi; Liu, Bin; Cao, Baocheng

    2014-08-01

    In this study, the radio frequency (RF) magnetron sputtering method was used to prepare a TiO2 thin film on the surface of stainless steel brackets. Eighteen groups of samples were made according to the experimental parameters. The crystal structure and surface morphology were characterized by X-ray diffraction, and scanning electron microscopy, respectively. The photocatalytic properties under visible light irradiation were evaluated by measuring the degradation ratio of methylene blue. The sputtering temperature was set at 300 °C, and the time was set as 180 min, the ratio of Ar to N was 30:1, and annealing temperature was set at 450 °C. The thin films made under these parameters had the highest visible light photocatalytic activity of all the combinations of parameters tested. Antibacterial activities of the selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. The results demonstrated the thin film prepared under the parameters above showed the highest antibacterial activity.

  18. Highly antibacterial activity of N-doped TiO{sub 2} thin films coated on stainless steel brackets under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Shuai; Liu, Bo; Fan, Lingying; Yue, Ziqi [Department of Orthodontics, School of Stomatology, Lanzhou University, Lanzhou 730000 (China); Liu, Bin [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Cao, Baocheng, E-mail: caobch@lzu.edu.cn [Department of Orthodontics, School of Stomatology, Lanzhou University, Lanzhou 730000 (China)

    2014-08-01

    In this study, the radio frequency (RF) magnetron sputtering method was used to prepare a TiO{sub 2} thin film on the surface of stainless steel brackets. Eighteen groups of samples were made according to the experimental parameters. The crystal structure and surface morphology were characterized by X-ray diffraction, and scanning electron microscopy, respectively. The photocatalytic properties under visible light irradiation were evaluated by measuring the degradation ratio of methylene blue. The sputtering temperature was set at 300 °C, and the time was set as 180 min, the ratio of Ar to N was 30:1, and annealing temperature was set at 450 °C. The thin films made under these parameters had the highest visible light photocatalytic activity of all the combinations of parameters tested. Antibacterial activities of the selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. The results demonstrated the thin film prepared under the parameters above showed the highest antibacterial activity.

  19. The construction of the referent The place where I live in opinion articles: a dialogue between referential theory and objectivity in brackets

    Directory of Open Access Journals (Sweden)

    Filipe Fontenele Oliveira

    2016-12-01

    Full Text Available This paper aims to propose a discussion about the construction of the referent The place where I live in the V edition of the Portuguese Language Olympiad Writing the Future, while trying to hold a dialogue between the theory of referentiation and the concept of objectivity in brackets proposed by biologist Humberto Maturana. Part of this discussion includes the partial results of our master's research in the Postgraduate in Applied Linguistics Program, State University of Ceará. In this research, we analyze nine texts of opinion written by students of a state school in Fortaleza, produced and intended for this educational event. However, for the current work, we analyze just one text. We seek to achieve the approximation of the theories under discussion in the production of the texts, including the reference articulation that cover The place where I live in the analyzed text. From what we see, the construction of this reference exceeds relations between the words marked by direct expressions or predications attached to it. In fact, it occurs in relation to other related available in text and occurs before the mention by linguistic expressions, as already part of individual and collective buildings, marked by sociohistoric aspects and the intertextual relations with other sources.

  20. 氟牙症患者对托槽粘接效果影响的临床研究初探%Clinical studies the affect of bracket bonded on dental fluorosis patient

    Institute of Scientific and Technical Information of China (English)

    姜国有; 王晓红

    2010-01-01

    目的 探讨影响氟斑牙患者对托槽粘接效果.方法 选取氟斑牙为轻、中、重患者30例,分成A、B、C 3组,年龄在14~20岁的患者,观察托槽粘接效果及时间.结果 轻度氟斑牙A组中轻扫牙面组托槽脱落率明显小于牙面未磨除组;中度氟斑牙B组釉质磨除0.1 mm组托槽脱落率明显小于牙面轻磨除组;重度氟斑牙C组釉质磨除量在0.15 mm以上组托槽脱落率明显小于牙面磨除0.1 mm组.结论 氟斑牙表层釉质的磨除能改变了釉质裘面的物理性状,可提高了粘接效果.%Objective To exploring the effective of patient with the fluorosis to the bracket bonded.Methods Selected 30 cases of patient, age range from 14ys to 20ys old with the dental fluorosis. They were divided into three groups as of A,B,C based on the degrees of mild,sever,and very sever. Observe the time and effect of bracket bonded. Results In mild fluorosis patient ( A group) , the bracket off rate was less in gently grinding dental surface than in non-grinding dental surface patient. In group B, bracket off rate enamel surface grinding 0. 1 mm group was smaller than gently grinding dental surface group; In group C, grinding dental surface in > 0. 15 mm were better than grinding dental surface in 0. 1 mm patient in bracket off rate. Conclusion Grinding the enamel surface of dental fluorosis could be in changing the physical properties of the enamel surface, and enhance the adhesive effect.

  1. Evaluation of the rate of bond failure of Discovery and Smart-Clip self-ligating brackets%Discovery自锁托槽和Smart-Clip自锁托槽脱落率的分析研究

    Institute of Scientific and Technical Information of China (English)

    陈慧霞; 沈云娟; 秦燕军; 许晓聪; 李媛; 陈文静

    2012-01-01

    目的 分析Discovery自锁托槽和Smart - Clip自锁托槽光固化湿粘接后托槽的脱落率.方法 随机抽取2009-2011年临床应用Discovery自锁托槽及Smart - Clip自锁托槽进行矫治的正畸病例,分别采用3M公司生产的TransbondTM XT光固化粘接剂管装+ TransbondTM MIP耐湿性处理液和APCTMⅡ预置粘接剂托槽+ TransbondTM MIP耐湿性处理液严格按照粘接要求进行粘接,记录其脱落情况,计算脱落率,并分析脱落原冈及其与口腔卫生之间的关系.结果 口腔卫生情况对于托槽脱落率有一定的影响;下颌同名牙托槽脱落率明显高于上颌;托槽脱落再粘接后发生再次脱落者主要集中在下颌.结论 临床应重视自锁托槽的粘接,加强患者口腔卫生保健,以降低托槽脱落率.%Objective To evaluate the rate of bond failure of Discovery and Smart-Clip self-ligating brackets. Methods Patients treated with Discovery or Smart-Clip self-ligating brackets in the year of 2009-2011 were selected randomly. Discovery self-ligating brackets were bonded with Transbond? XT and Transbond? MIP; Smart-Clip self-ligating brackets were bonded with APC? II and Transbond? MIP. The rate of bond failure was calculated. Its causes and its relationship with oral hygiene were analyzed. Results Oral hygiene had an effect on the rate of bond failure;the failure rates of lower teeth were obviously higher than those of upper teeth;the failure of rebonding mainly happened to lower teeth. Conclusions It is of great importance to bond self-ligating brackets properly and improve oral hygiene of patients,so that we can reduce the rate of bond failure.

  2. COMPARISON OF PERIODONTAL CONDITION BETWEEN CONVENTIONAL AND SELF-LIGATING BRACKETS%自锁托槽与传统托槽对正畸患者牙周健康影响的比较

    Institute of Scientific and Technical Information of China (English)

    李永花

    2015-01-01

    Objective To compareto impacts of self‐ligating brackets and conventional brackets on the periondontal health of the patient .Methods 50 patients (12 to 18 years old)were divided into 2 groups(group A :25 patients with self‐ligating brackets and group B :25 patients with conventional pre‐adjusted brackets) . Periodontal indices(GI ,PLl ,SBI and PD)were examined in both groups .Results Before treatment ,there is no significant difference between Group A and Group B .During the process of treatment ,PLI is statistical‐ly different between Group A and Group B ,other periodontal indices (GI ,SBI and PD) are not statistically different .Conclusion Although self‐ligating brackets is more beneficial for keeping oral hygiene ,but no significant difference were discovered on the patient’s periodontal health .%目的:比较自锁托槽与传统托槽对患者牙周健康的影响。方法选取12~18岁正畸患者50例,按矫治器类型分为两组:A组,25例戴用传统托槽矫治的患者;B组,25例戴用自锁托槽矫治的患者。分别于治疗前和治疗中1个月、3个月、6个月时检测两组患者的各项牙周指数(G I , PLI ,SBI ,PD)。结果矫治前,两组患者各项牙周指数无显著性差异( P >0.05);矫治过程中,两组患者的菌斑指数(PLI)有显著性差异( P <0.05),其余牙周指数(GI ,SBI ,PD)无显著性差异( P>0.05)。结论自锁托槽与传统托槽相比,在口腔卫生的维护方面更有优势,但二者对患者其他牙周健康的影响无明显区别。

  3. Biodegradação de braquetes ortodônticos: avaliação da liberação iônica in vitro Biodegradation of orthodontic brackets: in vitro ion release

    Directory of Open Access Journals (Sweden)

    Gabriel Schmidt Dolci

    2008-06-01

    Full Text Available OBJETIVO: avaliar, in vitro, a biodegradação de aparelhos ortodônticos simulados constituídos de braquetes e fios de aço inoxidável. METODOLOGIA: a amostra foi dividida em 2 grupos, de acordo com a marca dos braquetes usados: grupo A - Dyna-Lock, 3M/Unitek (AISI 303; e grupo B - LG Edgewise Standard, American Orthodontics (AISI 316L. Os corpos-de-prova permaneceram incubados em solução salina (0,05% a 36ºC, sob agitação por um período de até 60 dias. A análise da liberação iônica foi realizada por meio de espectrofotometria de absorção atômica. O peso em massa dos braquetes também foi medido antes e após o experimento. RESULTADOS: os resultados indicaram que o grupo A apresentou maior liberação de íons ferro, níquel e cromo do que o grupo B. Além disso, os braquetes do grupo A também mostraram perda de massa, considerada outro indicativo de corrosão. CONCLUSÃO: concluiu-se que, nas condições deste experimento, os braquetes do grupo A apresentaram maior biodegradação que os acessórios do grupo B, o que pode estar associado à liga metálica e/ou ao processo de fabricação dos mesmos.OBJECTIVE: The purpose of this study was to evaluate, in vitro, the biodegradation of simulated orthodontic appliances consisting of stainless steel brackets and wires. MATERIALS AND METHODOS: The sample was divided in 2 groups, according to brackets brand: group A - Dyna-Lock, 3M/ Unitek (AISI 303; and group B - LG Edgewise Standard, American Orthodontics (AISI 316L. The specimens (simulated orthodontic appliances were incubated in saline solution (0.05%, in shake, at 36ºC, for 60 days. The ion release was detected by atomic absorption spectrophotometer. The weight of brackets was also measured before and after the test. RESULTS: The results indicated that group A released more ions iron, nickel and chromium than group B. Moreover, the brackets in group A also presented weight loss, which is considered an indicator of corrosion

  4. Investigation into the bond strength of metal brackets to ceramic restoration%瓷修复体与金属托槽粘接强度的实验研究

    Institute of Scientific and Technical Information of China (English)

    王春晔; 邵玶; 赵媛; 徐实谦; 宋冰

    2012-01-01

    Objective To investigate the influence of different bracket base surfaces ( swallow-tail-backed and mesh-backed ) on the bond strength of metal brackets to porcelain. Methods Methods 80 ceramics specimen were randomly and equally divided into 4 groups according to different conditioning techniques: (A)deglazing by grinding and bonding swallow-tail-backed metal brackets, (B)deglazing by grinding and bonding mesh-backed metal brackets.(C) etching with 9.6% hydrofluoric acid(HF) and bonding swallow-tail-backed metal brackets, (D) etching with 9.6% HF and bonding mesh-backed metal brackets. Each group was further divided into 2 groups randomly and equally: (1) all specimens were stored in artificial saliva at 37t: for 24 hours, (2) untreated. Silane coupling agents and Durafill BondTM adhesive were utilized to bond the bracket onto each sample. The shear bond strength and the Adhesive remnant index (ARI) were determined. Results After artificial saliva bath.the swallow-tail-backed groups resulted in a statistically significant higher bond strength. Deglazing specimens,mesh-backed group in which has a statistically significant higher adhesive remnant index (ARI). Conclusion The swallow-tail-backed groups resulted in a higher bond strength (SBS). The deglazing group had a higher SBS than the group of etching with 9.6% hydrofluoric acid(HF) for 3 min.%目的:研究两种不同形状的底板(燕尾状、网状)对正畸金属托槽与瓷修复体粘接强度的影响.方法:根据瓷面处理方式及所粘接托槽的不同,将80个瓷修复体随机平均分为4组:金刚砂车针打磨+燕尾状底板托槽;金刚砂车针打磨+网状底板托槽;9.6%氢氟酸(hydrofluoric acid,HF)酸蚀+燕尾状底板托槽;9.6% HF酸蚀+网状底板托槽.将粘接后的每组瓷修复体随机平均分为2组:组1用37℃人工唾液水浴24h;组2不予处理.用硅烷偶联剂、杜拉菲勒光固化复合树脂充填材料进行粘接.检测抗剪

  5. Preliminary study on direct manufacturing of customized lingual brackets by selective laser melting%选区激光熔化直接成型个性化舌侧托槽的研究

    Institute of Scientific and Technical Information of China (English)

    孔卫东; 王淑范; 王迪; 卢建斌; 杨永强

    2012-01-01

    In order to investigate the feasibility of direct manufacturing customized lingual brackets by selective laser melting, firstly, a 3-D scanner was used to acquire and reconstruct teeth model, which was based on the customized lingual brackets designing with 3-D software; then customized metal lingual brackets were directly manufactured with a self-developed selective laser melting apparatus; finally the slot width of the bracket on front teeth was measured. The analysis shows that the teeth model obtained from the three dimensional laser scanner can meet the requirements for customized lingual brackets designing, and customized metal lingual brackets that can well fitted with teeth model can be produced precisely by selective laser melting process. Compared with the designed value 0. 460mm on CAD model, the slot width of the front teeth was measured 0. 471mm ±0. 009mm. The research proves it is feasible to manufacture precise and well fitted customized metal lingual brackets by means of selective laser melting technique.%为了探讨应用选区激光熔化快速成型技术直接制造个性化金属舌侧托槽的可行性,采用3维激光扫描仪采集与重建牙颌模型数据,并以该数字模型为基础,应用3维软件进行了个性化舌侧托槽的CAD设计,再通过自主研发的选区激光熔化快速成型机直接制造出个性化金属舌侧托槽,并对托槽的直接成型质量进行了理论分析和实验验证.结果表明,3维激光扫描仪获得的牙颌模型数据可以满足个性化舌侧托槽设计要求;应用选区激光熔化技术能够制造出与实际牙颌模型相一致的个性化舌侧托槽,取得了个性化前牙槽沟宽度为0.471mm±0.009mm数据,前牙槽沟宽度CAD设计值为0.460mm,两者间没有统计学上的差异(p>0.05).这一结果对选区激光熔化技术直接制造个性化金属舌侧托槽的实际应用是有帮助的.

  6. 纳米银羟基磷灰石涂层正畸陶瓷托槽的抗菌与力学性能%Antibacterial and mechanical properties of ceramic orthodontic brackets with nano silver hydroxyapatite coating

    Institute of Scientific and Technical Information of China (English)

    周冠军; 杨大鹏; 刘新芳; 胡博

    2015-01-01

    背景:临床口腔正畸过程中,陶瓷托槽存在抗菌性能和力学性能不足的情况,容易导致各种不良事件的出现,影响正畸效果。目的:观察纳米银羟基磷灰石涂层陶瓷托槽的抗菌与力学性能。方法:制备纳米银羟基磷灰石涂层陶瓷托槽,采用扫描电镜观察涂层表面,并进行涂层表面定量抗菌实验。将50颗离体人上颌前磨牙随机分为2组,实验组(n=25)粘接纳米银羟基磷灰石涂层陶瓷托槽,对照组(n=25)粘接普通陶瓷托槽,检测两组抗剪切强度。结果与结论:纳米银羟基磷灰石涂层整体结构有序,均匀致密,羟基磷灰石具有多孔状结构,孔径属于微纳米级别,其中均匀分布大量纳米银颗粒。定量抗菌实验显示,纳米银羟基磷灰石涂层陶瓷托槽对大肠杆菌、白色葡萄球菌有较强的抑制作用,抗菌率均在95%以上。实验组抗剪切强度低于对照组(P <0.05)。表明纳米银羟基磷灰石涂层陶瓷托槽具有良好的抗菌和力学性能,满足临床正畸过程中力学变化的需求。%BACKGROUND:In the clinical orthodontics, ceramic brackets have deficiencies in the aspects of antibacterial and mechanical properties, which easily lead to the emergence of a variety of adverse events and influence the orthodontic effect. OBJECTIVE:To observe the antibacterial and mechanical properties of nano silver hydroxyapatite coating ceramic brackets. METHODS:The nano silver hydroxyapatite coating ceramic brackets were prepared. Scanning electron microscopy was used to observe the coating surface. Coating antibacterial experiment was conducted. Totaly 50 in vitro human maxilary premolars were randomly divided into two groups (n=25 per group): experimental and control groups. Premolars in the experimental group were bonded to nano silver coating hydroxyapatite ceramic brackets, and premolars in the control group were bonded to ordinary ceramic brackets. The

  7. Biodegradação de braquetes ortodônticos: análise por microscopia eletrônica de varredura Analysis of biodegradation of orthodontic brackets using scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    Luciane Macedo de Menezes

    2010-06-01

    Full Text Available OBJETIVO: analisar, por meio de microscopia eletrônica de varredura, as alterações químicas e estruturais de braquetes metálicos submetidos a um processo de biodegradação in vitro. MÉTODOS: a amostra foi dividida em dois grupos, de acordo com a marca comercial dos acessórios - Grupo A = Dyna-Lock, 3M/Unitek (AISI 303 e Grupo B = LG Edgewise Standard, American Orthodontics (AISI 316L. Os corpos de prova, aparelhos ortodônticos simulados, permaneceram imersos em solução salina (0,05% por um período de 60 dias, a 37ºC, sob agitação. As alterações decorrentes da exposição dos acessórios à solução salina foram investigadas através da observação com microscópio eletrônico de varredura (MEV e análise da composição química (EDX, realizadas antes e após o período de imersão (T0 e T5, respectivamente. RESULTADOS: em T5, houve formação de produtos de corrosão sobre a superfície dos braquetes, especialmente no Grupo A, além disso, houve alterações na composição da liga metálica dos braquetes de ambos os grupos, sendo que, no Grupo A, houve redução dos íons ferro e cromo e, no Grupo B, redução de íons cromo. CONCLUSÃO: os acessórios do Grupo A apresentaram-se menos resistentes à biodegradação in vitro, o que poderia estar associado ao tipo de aço utilizado em sua fabricação (AISI 303.OBJECTIVES: The purpose of this study was to analyze, with the aid of scanning electron microscopy (SEM, the chemical and structural changes in metal brackets subjected to an in vitro biodegradation process. METHODS: The sample was divided into three groups according to brackets commercial brand names, i.e., Group A = Dyna-Lock, 3M/Unitek (AISI 303 and Group B = LG standard edgewise, American Orthodontics (AISI 316L. The specimens were simulated orthodontic appliances, which remained immersed in saline solution (0.05% for a period of 60 days at 37°C under agitation. The changes resulting from exposure of the brackets

  8. Analysis Method of the Solar Equipment Bracket Based on Approximate Linear Elastic Theory%基于近似线性弹性理论的太阳能设备支架稳性分析方法

    Institute of Scientific and Technical Information of China (English)

    毛潭; 冯志彬; 尹宇鹤; 潘博

    2015-01-01

    This article presents an instability analysis method based on approximate linear elastic theory ,for solving the installing stability issues of solar panels bracket supporting by ground column. Firstly ,we determined the bracket installing angle according to the simulation results of illumination conditions in Beijing area based on shadow ratio method and spherical trigonometry. Secondly,we used static analysis and linear buckling analysis method to anlyze and compare three representative bracket structures by checking their respective force loads ,structural strength and stability. Finally ,we verified the accuracy and reliability of instability analysis method based on approximate linear elastic theory through experiments.%针对地面立柱式太阳能电池板支架安装稳定性问题,引入基于近似线性弹性理论的失稳分析的方法求解。首先基于影子倍率法和球形三角函数法模拟北京光照情况并确定太阳能设备的支架安装角度;其次利用静力学分析法和线性屈曲分析法,通过分析比较三种有代表性的支架系统方案,分别计算出受力载荷、结构强度和稳定性;最后通过实例验证近似线性弹性理论的失稳分析方法的准确性和可靠性。

  9. Application of Using Ultra-Low-Speed Die Casting the Support Bracket of Automobile Engine Transmission%汽车发动机变速箱支架类零件的超低速压铸工艺

    Institute of Scientific and Technical Information of China (English)

    刘春生; 苏建强; 罗金祺

    2013-01-01

    针对传统压铸工艺在生产超厚型产品时存在的气孔率高、强度低等问题,研究开发了某发动机支架零件的超低速压铸工艺,讨论了不同压射速度、内浇口厚度、浇注温度以及模具结构和模温控制等因素对压铸产品质量的影响.结果表明,当低速压射速度为0.25 m/s,高速压射速度为0.5 m/s,内浇口厚度为5.2 mm,浇注温度为680~690℃时,获得的铸件质量最好.通过对超低速压铸模具结构进行改进,并采用顺序凝固模温控制方法,满足了对铸件进行T6热处理的要求,使产品性能有较大提升.%aiming at problems existed in the traditional die casting super-thickness product, such as high porosity, low strength, the ultra-low-speed die casting engine support bracket was conducted, and effects of different injection speed, the thickness of ingate, pouring temperature of liquid metal, the mould structure and the control methods of the mould temperature on the quality of die casting support bracket were discussed. The results show that the support bracket exhibits acceptable quality with low injection speed of 0. 25 m/s and high injection speed of 0. 5 m/s, thickness of ingate of 5. 2 mm as well as pouring temperature of 680~690 ℃. Through modifying die casting die structure and adopting the sequential solidification mould temperature, the support bracket ca be treated by T6 heat treatment, improving greatly the performance of the die castings.

  10. 驻车制动底板支撑座断裂分析%Fracture analysis of parking brake bottom brackets

    Institute of Scientific and Technical Information of China (English)

    吴双; 黄平; 谭江; 罗敏

    2016-01-01

    Several fracture failure accidents of parking brake bottom brackets occurred in succession during the road test of cars .Reasons of the fracture were studied by means of macroscopic fracture analysis , microstructure analysis , chemical composition analysis and mechanical properties testing of the raw materials and the scene of the production process survey .And corresponding improvement measures were proposed.The results show that the breaking of the supporting seat occurs from the outer surface , and no obvious fatigue characteristics and plastic deformation features observed .The brittle fracture is caused by over high induction heating temperature and over long soaking time , which leads to the appearance of widmanstatten .Widmanstatten can be avoided by regulating hot heading induction heating process and normalizing treatment after heading , therefore , no longer any fracture occurs in the following-up road test .%驻车制动底板支撑座在路试中陆续发生几起断裂失效事故。通过宏观断口分析、金相组织分析、原材料化学成分及力学性能检测以及结合现场生产工艺等分析查找零件失效的原因,并提出了相应的改进措施。结果表明,支撑座断裂起裂点在外表面,无明显疲劳特征和塑性变形特征,属于脆性断裂。这是由于热镦工序感应加热温度过高,时间过长,出现魏氏组织,且后序工艺没有消除该组织造成。通过管控热镦感应加热工序及热镦后正火处理,可消除魏氏组织,经该工艺生产的支撑座在后续路试中均未再发生断裂现象。

  11. Influence of electric toothbrushes to bracket failure and gingival health in patients with fixed appliances%电动牙刷刷牙对正畸患者牙龈炎症和托槽脱落的影响

    Institute of Scientific and Technical Information of China (English)

    余新洲; 尹璐; 喻建; 高育德

    2011-01-01

    49 patients undergoing orthodontic treatment with fixed appliances were included in the study.The patients were required to brush teeth with electric toothbrushes on one side and manual toothbrushes on another side.The bracket failure on electric toothbrush brushed side was more than that on manual.Bracket failure in male was more than in female.%戴有固定矫治器的正畸患者分别使用电动牙刷和手动牙刷刷牙,以了解电动牙刷对托槽脱落和牙龈炎症的影响.结果显示电动牙刷刷牙的托槽脱落率高于手动牙刷,男性的托槽脱落率高于女性.对于固定矫治的正畸患者而言,电动牙刷刷牙在减少牙龈炎症方面并不优于手动牙刷,且使用电动牙刷更加容易造成托槽的脱落.

  12. Aseismic Test of Stationary Lead-acid Batteries and Brackets Based on Nuclear Safety Level%核安全级固定型铅酸蓄电池组及支架抗震试验研究

    Institute of Scientific and Technical Information of China (English)

    杨勇; 宫必宁; 张莹莹

    2011-01-01

    According to the aseismic test of stationary lead acid batteries and the brackets with nuclear safety level,the mathematical model is established to calculate the seismic response of the brackets by using finite element response spectrum method and equivalent static method. Compared with the experimental data, the results show that the response spectrum finite element method has better precision and reasonableness than the equivalent static method, which also has a conservative margin.%基于核安全级固定型铅酸蓄电池组及支架抗震试验,构建了相应数学分析模型,采用反应谱有限元法和等效静力法计算了支架地震响应,并与试验数据进行了对比.结果表明,反应谱有限元计算结果相对于等效静力计算结果相对精确、合理,且有一定保守裕度.

  13. Perioperative managements for patients with heart bracket who undergoing abdominal surgery%围腹部手术期患者伴有心脏支架的处理策略

    Institute of Scientific and Technical Information of China (English)

    胡祥; 曹亮

    2016-01-01

    美国心脏病学会联合美国心脏协会( ACC/AHA)和欧洲的心脏协会( ESC)相继发布了非心脏手术围手术期心血管评估与治疗指南推荐,对心脏支架患者非心脏手术围手术期的治疗提出指导意见,但是对非心脏手术的时机选择、围手术期抗凝治疗等问题仍有争议。掌握心脏支架患者腹部围手术期的处理相关策略,对减少围手术期心脏相关并发症至关重要。%The guidelines of perioperative cardiovascular evaluation and managements of patients undergoing noncardiac surgery have been published recently by ACC /AHA and European Society of Cardiology(ESC).Guideline proposed recommendations of the treatment of patients with heart bracket who undergoing non-cardiac surgery . However the optimal timing of non-cardiac surgery , perioperative anticoagulation and other issues remained to be controversial .Mastering the therapeutic strategies of patients with heart bracket would be essential to reduce perioperative cardiac complications .

  14. 某重卡下支架有限元分析及轻量化设计%Finite element analysis and Lightweight Design of A Heavy TruckLower bracket

    Institute of Scientific and Technical Information of China (English)

    张龙; 王晓磊; 张阳光; 冯江峰

    2014-01-01

    Finite element analysis was performed on the static strength properties under design conditions of a heavy truck lower bracket, and lightweight design was performed. Using topology optimization method, iterative calculations for optimization were performed, the maximum design space was taken as the base structure of optimization, the lightest weight was taken as the objective function, the structural static strength properties was taken as the constraints. After the lightweight design, the lower bracket weight was reduced, and the lightweight structure met strength requirements.%对某重卡下支架在设计工况下的静强度性能进行了有限元分析,并对该下支架结构进行了轻量化设计。采用拓扑优化方法,以最大设计空间为优化的基结构,以重量最轻为目标函数,以结构的静强度性能为约束条件,进行了优化迭代计算。轻量化设计后,减轻了下支架的重量,且轻量化结构满足强度要求。

  15. 独柱盖梁上、下双抱箍托架设计及施工%Design and Construction of Single - column Capping Beam Upper and Lower Double Embracing Hoop Brackets

    Institute of Scientific and Technical Information of China (English)

    夏龙

    2012-01-01

    根据独柱盖梁对称浇筑的施工特点,结合连续刚构(梁)0号块托架法现浇施工和双柱抱箍法盖梁施工的相关经验,设计了上、下双抱箍加设三角托架的独柱盖梁支撑结构;并对其主要构件设计、施工流程、质量安全方面注意事项进行了分析和总结,为类似工程提供参考和借鉴。%According to construction characteristics of single - column capping beam symmetric casting and in combination with relevant experience of cast construction through continuous rigid frame ( beam ) No. 0 block bracket method and capping beam construction through double - column embracing hoop method, single - column capping beam support structure of upper and lower double embracing hoop with triangle brackets is designed and the main component design, construction process, and matters needing attention in the aspect of quality safety are analyzed and summarized, providing reference for similar projects.

  16. Influence of bonding time on bond strength of metallic orthodontic bracket with etching base.%粘结时间对微蚀刻底托槽粘结强度的影响

    Institute of Scientific and Technical Information of China (English)

    杨瑞; 魏志民; 杨凯云; 张栋; 赵婧; 孙佩佩; 潘淑勤

    2012-01-01

    目的:对比微蚀刻底托槽粘结后不同时间的粘结强度,寻找合适的力的加载时机.方法:随机挑选对称性拔除上下颌第一前磨牙正畸患者30例,分为A、B、C三组进行全口微蚀刻底托槽粘结,分别在粘结后5 min,30 min,60min进行弓丝结扎,统计患者第一次复诊时托槽脱落率.将30例患者拔除的上颌第一前磨牙60颗,随机分成1~6组,每组10颗.1~6组离体牙粘结微蚀刻底直丝托槽,分别在粘结后5 min,10 min,15 min,30 min,60 min,24h进行抗剪切强度(SBS)测定,并统计粘结剂残留指数(ARI),扫描电镜观察托槽粘结前后底板形貌.结果:微蚀刻底托槽在体外粘结后24 h抗剪切强度达到最大.结论:微蚀刻底托槽的粘结强度能够满足临床需要,临床医师可在托槽粘结后5 min进行力的加载.%Objective: To measure the SBS of bracket with etching base at different time after bond and to find the appropriate time to load the bracket. Method: A total of 30 patients were randomly divided into 3 groups (10 per group) .480 bracket were bonded for them. They were loaded at 5 min,30 min,60 min seperately,and were observed for the first return visit.The failure of debond were recorded .Sixty youth maxillary first premolars extracted from the 30 patients above were randomly divided into 6 groups(10 per group). The shear bond test of group 1~6 was performed at different debond time of 5 min, 10 min, 15 min, 30 min, and 60 min and 24 hours. The chisquared test was used to determine signi? Cant differences for the ARI scores among the groups Ip < 0.05). Result: Highest shear bond strength was obtained with a debond time of 24 hours and the SBS was signi? Cantly different (P <0.001). Conclusion: Bracket with etching base is to meet the clinical requirement.lt is reliable to load the bracket 5 minutes after it is bonded.

  17. Interferência dos diferentes glazeamentos na colagem de bráquetes ortodônticos em superfícies cerâmicas Effects of the different glazed ceramic surfaces on the bond of orthodontic brackets

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    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

  18. Different bottom structure of dental brackets affect the adhesiveness——Three dimensional finite-element analysis%三维有限元模型分析不同牙齿托槽底板结构对粘接强度的影响

    Institute of Scientific and Technical Information of China (English)

    殷桢; 于渤; 曲虹

    2012-01-01

    The aim of the study is to establish different bottom structures of dental brackets model in FEM(finite element analysis) , and analyze the affect of different bottom structures on bond strength of dental brackets to enamel. [Methods] In the light of the size of standard edgewise brackets, tooth - cement - bracket models with different bottom structure were built on the computer and were loaded three types of force respectively. The stress and deformation distribution were analyzed. [ Results ] (1 ) The brackets generally show the best anti - destructibility under the shearing force, worst under the twisting force. (2)The brackets generally show the best anti 梔eformation under the tension, worst under the twisting force. ( 3 ) The triangle gridding bottom structure bracket we designed shows the relatively better retention capacity, and rhombus gridding one is just the reverse. [Conclusion] According to the force distribution and the deformation on the bottom structure, we conclude the triangle gridding bottom structure bracket we designed has relatively better retention capacity, and rhombus gridding one has poor retention capacity.%[目的]建立不同底板结构的牙齿托槽的三维有限元模型,分析不同托槽底板结构对粘接质量的影响.[方法]依据标准方丝弓托槽的尺寸,建立牙-粘接剂-托槽系统不同托槽底板的三维有限元模型.在模型上分别施加同样大小的三种外力,分析底板的应力分布和形变情况.[结果](1)剪切力作用下托槽的抗破坏力最强,扭转力最易产生界面的粘接破坏.(2)拉力作用下托槽的抗形变能力最强,扭转力作用下托槽的抗形变能力最差.(3)设计的三角形网底托槽的固位能力相对较好,菱形网底托槽相对较差.[结论]综合底板应力分布和形变情况,设计的三角形网底托槽的粘接效果相对较好,而菱形网底托槽的固位能力相对较差.

  19. Comparative study on inflammatory cytokine levels in gingival crevicular fluid during orthodontic tooth movement with Smart Clip self-ligating brackets and conventional brackets%Smart Clip 自锁托槽和传统托槽对正畸牙龈沟液中炎症因子水平的影响研究

    Institute of Scientific and Technical Information of China (English)

    韩骁; 刘昕; 张晏更; 葛宇

    2014-01-01

    Objective To investigate changes of the cytokine levels in the gingival crevicular fluid after applying force on the self-li-gating brackets and conventional brackets,and analyse the periodontal tissue remodeling.Methods Sixteen maxillary protruding pa-tients who needed removing bilateral maxillary first premolars were selected,self-ligating appliance being used on one side of the upper dentition as the experimental group,and using traditional straight wire appliance on the other side as the control group.IL-1 βand PGE2 levels of the gingival crevicular fluid taken at different time points in canine retraction were detected,and to analyze the relationship of their changes with periodontal tissue inflammatory response.Results After retruding the canines,levels of IL-1 βand PGE2 of the gin-gival crevicular fluid all increased and reached their top at 24 h.There were no significant differencesin IL-1 βand PGE2 levels of the gingival crevicular fluid between the experimental group and control group.Conclusions Self-ligating appliance did not differ signifi-cantly from traditional appliance in periodontal tissue remodeling in the early phase of the orthodontic tooth movement.%目的:探讨自锁矫治器和传统矫治器对牙齿加力后龈沟液中炎症因子水平变化从而比较两种类型托槽引起的牙周组织改建的情况。方法选择16例上颌前突需拔除上颌双侧第一前磨牙的患者,上牙列一侧使用自锁矫治器作为试验组,一侧使用传统直丝弓矫治器作为对照组,对两侧尖牙加力后取不同时间点的龈沟液,检测其中 IL -1β和 PGE2水平,分析其变化与牙周组织炎症反应的关系。结果在对尖牙加力后,龈沟液中 IL -1β和 PGE2水平均升高,均在加力后24 h 达到最高值,各检测时间点试验组和对照组龈沟液中 IL -1β和 PGE2含量差异无统计学意义(P>0.05)。结论2种矫治器在正畸牙移动的初期对牙周组织改建的影响无明显区别。

  20. Assessment of surface friction of self-ligating brackets under conditions of angulated traction Avaliação da fricção superficial apresentada por braquetes autoligáveis em condições de tracionamento sob angulação

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    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

  1. Diagnóstico de resistência do Mycobacterium tuberculosis à rifampicina utilizando-se da reação em cadeia da polimerase Diagnostic of rifampicin-resistance of Mycobacterium tuberculosis by polymerase chain reaction

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    Wânia da Silva Carvalho

    2007-03-01

    Full Text Available A resistência do Mycobacterium tuberculosis aos tuberculostáticos tem surgido como grande ameaça à Saúde Pública. A resistência à rifampicina pode ser considerada como um marcador para a multi-resistência a fármacos e tem sido atribuída a mudanças estruturais da RNA polimerase, produto de expressão do gene rpoB. Os pacientes portadores dessas cepas têm baixa perspectiva frente ao tratamento. Os testes convencionais de sensibilidade aos fármacos realizados em cultura do Mtb requerem várias semanas para o crescimento. Por este motivo, a Reação em Cadeia da Polimerase (PCR, método de baixo custo e que pode reduzir o tempo para o diagnóstico, representa alternativa viável e promissora. Neste artigo estão descritos os métodos mais comumente empregados na detecção de mutantes resistentes à rifampicina baseados na PCR, como análise de Polimorfismo Conformacional de Fita Simples (Single-Strand Conformation Polymorphism, SSCP, PCR Heteroduplex e INNO-LIPA. Recentemente, padronizou-se a técnica de PCR em baixa estringência, usando um único iniciador (Low Stringency Single Specific Primer, LSSP, que se mostrou um método rápido e sensível na detecção de mutações no gene rpoB.The resistance of Mycobacterium tuberculosis to tuberculostatic drugs has emerged as a major public health threat. The resistance to rifampicin which has been attributed to structural changes in RNA polymerase can be considered as a marker for multi-drug-resistance to tuberculosis (MDR-TB. Patients bearing rifampicin-resistant strains have poor diagnosis even with treatment. Conventional culture-based drug sensibility testing can require several weeks due to the growth. In this paper we describe the most common PCR-based methods for detection of mutations that lead to rifampicin resistance, such as Single-Strand Conformation Polymorphism (SSCP, PCR Heteroduplex and INNO-LIPA. Recently, by Low Stringency using a Single Specific Primer (LSSP assay, it was standardized a protocol that showed to be rapid and sensitive for the detection of mutations in the rpoB gene.

  2. Estimativa da evapotranspiração real diária utilizando-se imagens digitais TM - Landsat 5 Assessment of daily actual evapotranspiration using TM - Landsat 5 digital images

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    Bergson G. Bezerra

    2008-09-01

    Full Text Available A quantificação da evapotranspiração é de grande importância na modelagem hidrológica e meteorológica, sendo indispensável no manejo hídrico sustentável de cultivos irrigados. Neste sentido, o presente trabalho tem por objetivo estimar a evapotranspiração real diária - ETr, em escalas local e regional, através de imagens TM - Landsat 5 e dados complementares coletados em estação meteorológica, através da aplicação do SEBAL - Surface Energy Balance Algorithm for Land. A área estudada fica localizada no Cariri cearense, sendo composta por áreas irrigadas, vegetação nativa e parte da floresta da Chapada do Araripe. Foram utilizadas quatro imagens, obtidas em 29 de setembro, 15 e 31 de outubro e 16 de novembro de 2005. A ETr diária foi estimada a partir da densidade de fluxo de calor latente (LE, obtida como resíduo da equação do balanço de energia. O SEBAL é constituído de várias etapas, que incluem calibração radiométrica, cômputo da reflectância e albedo, índices de vegetação e emissividade, baseados nas bandas reflectivas de sensores orbitais, e neste caso o TM - Landsat 5, além da temperatura da superfície (banda termal. Os resultados obtidos foram validados com medições da ETr obtidas em dois campos irrigados com mamona (Ricinus communis L. e algodão (Gossypium hirsutum. A ETr diária média da área estudada apresentou valores de 3,8, 3,7, 4,6 e 3,4 mm.dia-1, para os dias 272, 288, 304 e 320, respectivamente. Quando comparados com medidas efetuadas nos campos irrigados de algodão e mamona os valores da ETr estimados pelo SEBAL apresentaram diferenças inferiores a 1,0 mm dia-1, evidenciando a sua importância e acurácia.Quantification of evapotranspiration is of great importance for hydrological and meteorological modeling and indispensable for water management of irrigated crops. In this sense the main objective of this study was the estimation of actual daily evapotranspiration (Etr, in local and regional scale, utilizing the SEBAL (Surface Energy Balance Algorithm for Land. The TM - Landsat 5 images and weather data were used in order to assess the energy balance components. The studied area is located in Cariri region, Ceará State, and is composed by irrigated areas, native vegetation and part of the Chapada do Araripe Reserve. Four TM - Landsat 5 images of September 29th, October 15th, October 31st and November 16th of 2005, were used. Daily ETr was estimated based on the density of latent heat flux, obtained as residue of the energy balance equation. The application of the SEBAL algorithm includes some steps as radiometric calibration, estimation of the reflectance and albedo, emissivity and vegetation index, based on the reflective bands of the orbital sensors and further on the surface temperature (thermal band for the TM - Ladsat 5. Two irrigated fields of castor bean and cotton were used do validated the ETr estimated values. The reference evapotranspiration was obtained by FAO-Penman-Monteith method. The mean daily ETr over the studied area presented values of 3.8, 3.7, 4.6 and 3.4 mm.dia-1 on 29/09, 15/10, 31/10 and 16/11, respectively. When compared to measured data in the castor bean (Ricinus communis L. and cotton (Gossypium hirsutum irrigated crops, the ETr values obtained with SEBAL present differences smaller than 1,0 mm day-1, showing its importance and accuracy.

  3. Cultivo hidropônico de tomate cereja utilizando-se efluente tratado de uma indústria de sorvete Hydroponic production of cherry tomatoes using treated effluent of ice cream industry

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    Samuel M. M. Malheiros

    2012-10-01

    Full Text Available O objetivo deste trabalho foi avaliar o uso de doses de efluente oriundo de indústria de sorvete, na cultura do tomate cereja em relação ao consumo hídrico e no desenvolvimento vegetativo em sistema hidropônico. O delineamento experimental foi o inteiramente casualizado, com seis tratamentos e quatro repetições. Os tratamentos foram compostos pelo uso de doses de efluente (0, 25, 50, 75 e 100% com complementação de nutrientes e com o uso de 100% de efluente sem complementação nutriente. O aumento das doses de efluente na solução nutritiva proporcionou redução linear no consumo hídrico. O efluente com 25% proporcionou a melhor produtividade. A adição de até 50% de efluente de sorvete à solução nutritiva permitiu o cultivo de tomate cereja sem redução na produtividade, com melhor eficiência do uso da água na produção de matéria seca da parte aérea, produção de frutos e máxima substituição de minerais solúveis na solução nutritiva.The objective of this study was to evaluate the effect of ice cream raw effluent doses on consumption and vegetative development of cherry tomato under hydroponic system. The experiment was conducted in completely randomized design with six treatments and four replications. Treatments consisted of 5 different levels of effluent (0, 25, 50, 75 and 100% complemented with the amount of nutrient recommended for growing tomatoes and 100% of effluent without nutrient complementation. Increasing doses of effluent provided linear reduction in water consumption.Addition of effluent in proportion of 25% provided best production results. Addition up to 50% ice cream effluent to nutrient solution allowed growth of cherry tomato without yield reduction providing better efficiency of water use in terms of dry weight of shoots and fruit production as well as maximum substitution of soluble mineral fertilizers in nutrient solution.

  4. Diagnóstico do estado nutricional de N em porta-enxertos de citros, utilizando-se de teores foliares de clorofila Diagnostic of nitrogen nutritional level in citrus rootstocks using foliar chlorophyll content

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    ANTÔNIO DECARLOS NETO

    2002-04-01

    Full Text Available Objetivou-se, neste trabalho, avaliar os teores foliares de clorofila total (a+b em porta-enxertos de citros cultivados em tubetes, como índices no diagnóstico do estado nutricional de N, de acordo com adição das doses de N (0; 400; 800; 1.600; 3.200 e 4.800 mg/dm³ de N no substrato. Os teores foliares de clorofila total apresentaram alta correlação positiva com a altura, diâmetro do caule, massa da matéria seca da parte aérea e raízes, área foliar e teor de N-NO3 da parte aérea dos porta-enxertos, indicando a possibilidade de serem utilizados como índices para o diagnóstico de N em porta-enxertos cultivados em tubetes. Aos 120 dias após a semeadura, os teores foliares máximos de clorofila total dos porta-enxertos 'Tangelo-Orlando', 'Cravo', 'Volkameriano', 'Cleópatra' e 'Sunki' ocorreram quando foram aplicadas as doses 1.461; 2.386; 2.494 1.444; e 2.284 mg/dm³ de N no substrato, respectivamente. Os teores foliares adequados de clorofila total do porta-enxerto 'Tangelo-Orlando' devem estar compreendidos na faixa de 1,80 a 3,00 mg de clorofila total/dm² de folha, aos 120 dias após a semeadura. Para o limoeiro-'Cravo' esta faixa deve ser de 2,46 a 3,94 mg de clorofila total/dm² de folha, sendo que, para o limoeiro-'Volkameriano', esta faixa deve ser de 2,27 a 4,23 mg de clorofila total/dm² de folha. Para a tangerineira 'Cleópatra', a faixa adequada dos teores foliares de clorofila total deve ser de 3,29 a 4,00 mg de clorofila total/dm² de folha, sendo que, para a tangerineira-'Sunki', esta faixa deve ser de 1,80 a 3,16 mg de clorofila total/dm² de folha.The objective of this work was to evaluate chlorophyll content (a+b on 'Cravo', 'Cleópatra', 'Sunki', 'Volkameriano' and 'Tângelo Orlando' rootstocks in tubes using as indicator on diagnosis by increasing N doses (0; 400; 800; 1,600; 3,200; 4,800 mg N/dm³ of substrate. The chlorophylls content presented righ positive correlation to height, diameter, aerial portion and roots dry matter mass, foliar area and NO3-N content for aerial portion, indicating that the total chlorophyll content can be used as indicator to diagnose N in citrus rootstocks cultivated in tubes. The maximum chlorophylls content estimated in rootstocks 'Tangelo-Orlando', 'Cravo', 'Volkameriano', 'Cleópatra' e 'Sunki' occurred in doses 1,461; 2,386; 2,494; 1,444; and 2,284 (mg N/dm³ of substrate, respectively. Total foliar chlorophyll content adequate for rootstocts of 'Tangelo Orlando' showed to be placed between 1.80 to 3.00 mg of total chlorophyll/dm² of leaf at 120 days after sowing, for lemon 'Cravo' between 2.46 to 3.94 while the 'Volkameriano' showed to be placed between 2.27 to 4.23 mg of total chlorophyll/dm² of leaf. Adequate values for foliar contents for total chlorophyll for Cleopatra tangerine showed to be 3.29 to 4.00 mg of total chlorophyll/dm² of leaf while for 'Sunki' tangerine the values showed to be 1.80 to 3.16 mg of total chlorophyll/dm² of leaf.

  5. Estimativa da entalpia reticular de adutos (DM Hm o utilizando-se formas modificadas da equação de Kapustinskii Estimating the value of lattice enthalpy (DM Hm o for adducts by using modified forms of Kapustinskii equation

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    Robson Fernandes de Farias

    1999-04-01

    Full Text Available In this work are presented two modified forms of Kapustinskii equation that could be used to estimate the values of the lattice enthalphies for adducts: DM Hm o=(-n.z+ .z- .10(2/D.(1-d*/D .K and DM Hm o=(-n.z+ .z-.10(2/d.(1-d*/d.K.d. Two new parameters related with steric effects and donor power of the ligands, J anddare introduced. The proposed equations were tested for 49 adducts (mainly from the zinc group halides. The difference between experimental (calorimetric and calculated values (using the proposed equations values are less than 5% for 41 of the tested adducts.

  6. INFLUÊNCIA DA REFRIGERAÇÃO NA PRESERVAÇÃO DO NÚMERO TOTAL DE HEMÓCITOS DE CAMARÕES MARINHOS Litopenaeus vannamei CULTIVADOS UTILIZANDO-SE CITRATO DE SÓDIO

    Directory of Open Access Journals (Sweden)

    Andréa Christianne Gomes Barretto

    2012-12-01

    Full Text Available For carrying out blood cell count, the use anti-coagulants is necessary, and in the specific case of the hemolymph in shrimp, there is still no standard solution to avoid its coagulation. Sodium citrate is frequently used as anti-coagulant, because it has been previously proven to be efficient in the preservation of the hemocytes of the sea shrimp Litopenaeus vannamei. In 140 samples of hemolymph with sodium citrate (10% in the ratio of 1:1, collected at 2 stages of cultivation, in dry and wet season, were examined for HTC immediately after collection and then again after storage in the refrigerator. All data were analyzed using modeling mathematics formulas (P < 0.05. After storage in the refrigerator, the number of cells decreased considerably. Therefore, the anticoagulant sodium citrate only preserved the hemolymph of the shrimp Litopenaeus vannamei for HTC when the count was done immediately after collection.

  7. Forecasting of harmonics distortions in electric power systems, using impedance matrix of harmonic bus; Previsao de distorcoes harmonicas em sistemas eletricos de potencia, utilizando-se matriz impedancia de barra harmonica

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Clider Adriane de Sousa

    1993-11-01

    The present work is a contribution to the study of harmonics in electric power systems. It presents a focus returned to the planning area, in the sense of evaluating in a qualitative way the possible situations of harmonic distortions of voltage that can occur when of the installation of electric loads with not-linear behaviors in a power system. Using the domain of the frequency, as well as a monophase treatment, it intends to present a computational method of simple and fast processing to be used for evaluation of these harmonic distortions of voltage in power systems. Its main characteristic is the methodology used for the treatment of the harmonic injections on the part of non-linear loads, that it allows to supply a previous diagnosis of the behavior of the system, before the presence of such loads, before even of its effective installation.

  8. Produção de pimenta tabasco com aplicação de CO2, utilizando-se irrigação por gotejamento = Tabasco pepper production with CO2 application using drip irrigation

    Directory of Open Access Journals (Sweden)

    Fabiana Luiza Matielo de Paula

    2011-01-01

    Full Text Available A aplicação de CO2 via água de irrigação produz o rebaixamento do pH da solução do solo, causando variações na mobilidade dos nutrientes e consequentes efeitos na absorção. O objetivo deste trabalho foi analisar os efeitos de doses de dióxido de carbono (CO2, aplicadas via irrigação por gotejamento, na produção da pimenta Tabasco. O delineamento experimental foi o de blocos casualizados com quatro tratamentos e oito repetições. Os tratamentos foram quatro doses de CO2: 0 (T1, 451,95 (T2; 677,93 (T3 e 903,92 (T4 kg ha-1. Os frutos foram pesados e contados; o comprimento e o diâmetro de frutos foram obtidos com a média de 20 frutos por planta. Ocorreu efeito quadrático (p Application of CO2 through water reduces the soil solution pH, causing variations in nutrient mobility and consequent effects on the absorption. The objective of this study was to analyze the effects of carbon dioxide rates supplied by drip irrigation in the production of Capsicum frutescens L. crop. A randomized block design with four treatments and eight replications was used. The treatments were four rates of CO2: 0 (T1, 451.95 (T2; 677.93 (T3 and 903.92 (T4 kg ha-1. The fruits were counted and weighed; the length and the diameter were obtained from an average of 20 fruits per plant, randomly taken, from each treatment in the plot. The quadratic effect (p < 0.01 occurred for CO2 on the yield and there was quadratic effect (p < 0.05 of the rates on the number of fruits. There were no effects of CO2 rates on the green matter, dry matter and fruit length and diameter. The T2 treatment provided greater yield and higher number of fruits per plant with an increase of 16 and 26%, respectively in relation to T1 (without CO2. CO2 application favored the increase in the yield because of the greater number of fruits per plant in the Tabasco pepper crop.

  9. Use of sewage treatment biogas for electric generation using an 30 kW (ISO); Uso do biogas de tratamento de esgoto, para geracao de energia eletrica, utilizando-se de uma microturbina de 30 kW (ISO)

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, Suani T.; Velazquez, Silvia M.S.G.; Martins, Osvaldo S.; Costa, David F. [Centro Nacional de Referencia em Biomassa (CENBIO), Sao Paulo, SP (Brazil); Bacic, Antonio C.K. [Companhia de Saneamento Basico do Estado de Sao Paulo (SABESP), SP (Brazil)

    2004-07-01

    This paper intends to present some considerations directed to electricity generation with 30 kW (ISO) micro turbines, using biogas generated by sewage treatment process in SABESP (Basic Sanitation Company of Sao Paulo State), located at Barueri, Brazil. This project, pioneer in Latin America, is being accomplished together with BUN - Biomass Users Network of Brazil (proponent), in association with CENBIO - The Brazilian Reference Center on Biomass (executer), with patronage of FINEP / CT-ENERG (financial backer), by means of ACCORD No: 23.01.0653.00, regarding to ENERG-BIOG Project - 'Installation and Tests of an Electric Energy Generation Demonstration Unit from Biogas Sewage Treatment'. Thus, the contribution of this paper will be in the presentation of the project results, related with the exploitation of sewer biogas for power generation, as well as bigger details about purification, compression and electricity generation systems (biogas micro turbine) used in the installation. (author)

  10. Estimativa da transpiração em cafeeiros utilizando-se sensores de dissipação térmica Estimation of transpiration in coffee crop using heat dissipation sensors

    OpenAIRE

    Jussálvia da S. Pimentel; Tonny J. A. Silva; João C. F. Borges Júnior; Marcos V. Folegatti; Montenegro, Abelardo A. A.

    2010-01-01

    Alguns métodos são capazes de determinar diretamente a quantidade de água consumida por uma planta, entre eles o "método de dissipação de calor" ou método de Granier. Neste trabalho se propôs, como objetivo, construir e calibrar sensores de dissipação térmica, avaliar a transpiração em função da posição de inserção do sensor na planta (Norte, Sul, Leste ou Oeste) e comparar os resultados com os elementos meteorológicos e a evapotranspiração de referência. Em 24 cafeeiros se instalaram sensore...

  11. Diagnóstico de sífilis em lesões orais. Estudo comparativo utilizando-se as técnicas histoquímica e imuno-histoquímica

    OpenAIRE

    Carla Silva Siqueira

    2012-01-01

    A sífilis é uma doença infecciosa, cujo agente etiológico é o Treponema pallidum. Pode ser transmitida sexualmente ou verticalmente, via placenta. Seus estágios variam entre sífilis primária, sífilis secundária, sífilis latente e sífilis congênita. Dentre os diagnósticos mais eficazes, encontram-se os testes sorológicos, porém os falsos positivos e falsos negativos no estágio primário levam à procura de uma forma mais eficaz de se determinar, precocemente, a doença. Além disso, por várias raz...

  12. Processamento de sementes de Moringa oleifera utilizando-se diferentes equipamentos para obtenção de solução coagulante Processing of Moringa oleifera seeds using different equipments to obtain coagulant solution

    Directory of Open Access Journals (Sweden)

    Camila C. Arantes

    2012-06-01

    Full Text Available Desenvolveu-se este trabalho para avaliar o uso de quatro equipamentos no processamento das sementes de Moringa oleifera, visando à produção de solução coagulante a ser empregada no tratamento de água com turbidez obtida sinteticamente. Seis soluções coagulantes com diferentes tipos de processamento foram utilizadas em ensaios de coagulação, floculação e sedimentação em equipamento Jar-Test. A dosagem da solução coagulante utilizada foi 500 mg L-1 e os parâmetros avaliados foram turbidez e cor aparente; verificou-se, após 30 min de sedimentação, que para redução de turbidez e cor aparente os melhores processamentos foram com pilão e máquina de moer, respectivamente, sendo que em ambos os casos o peneiramento do pó foi essencial para a redução dos parâmetros em questão. Através de liquidificador e mixer, os índices de redução de turbidez e cor aparente foram os menores encontrados e a trituração das sementes durante o processamento na máquina de moer e no pilão remove parte do óleo neles presente, o que não ocorre com o uso do liquidificador e mixer, evidenciando que a retirada do óleo presente nas sementes resulta em solução coagulante com maior eficiência.This work was condcted to assess four different equipments used in processing seeds of Moringa oleifera to produce a coagulant solution to be used in water treatment with the turbidity obtained synthetically. Six coagulant solutions with different types of processing were used in assays of coagulation, flocculation and sedimentation in Jar-Test equipment. The dose of coagulant solution was 500 mg L-1 and the evaluated parameters were turbidity and apparent color. After 30 min of sedimentation, it was clear that the best processes to reduce turbidity and apparent color were the pestle and grinder, respectively, however, in both cases the sieving of the powder was essential in reducing the parameters in question. Using a blender and a mixer the reduction rates of turbidity and apparent color were the lowest. The grinding of the seeds during processing in the grinder and the pestle remove part of the oil present in them, which does not occur when using the blender and mixer, stating that the removal of oil present in the seeds result in a more efficient coagulant solution.

  13. Fitorremediação de solos contaminados com tebuthiuron utilizando-se espécies cultivadas para adubação verde Phytoremediation of tebuthiuron-contaminated soils using species cultivated for green manure

    Directory of Open Access Journals (Sweden)

    F.R. Pires

    2005-12-01

    Full Text Available O emprego da fitorremediação na despoluição de solos contaminados com compostos orgânicos, inclusive herbicidas, vem sendo pesquisado ultimamente. Como o tebuthiuron pode causar sério impacto ambiental, por ser muito utilizado, apresentar longo efeito residual no solo e possibilidade de contaminação do lençol de água subterrâneo, desenvolveu-se este trabalho com o objetivo de avaliar a capacidade de sete espécies vegetais na despoluição de solos contaminados com esse herbicida. As espécies avaliadas neste experimento foram: Cajanus cajan, Canavalia ensiformes, Dolichos lablab, Pannisetum glaucum, Estizolobium deeringianum, Estizolobium aterrimum e Lupinus albus. Elas foram semeadas e cultivadas, por 60 dias, em vasos cujo solo recebeu quatro doses do tebuthiuron (0,0; 0,5; 1,0; e 1,5 kg ha-1. As testemunhas foram constituídas por vasos sem planta, aos quais foram aplicadas as mesmas doses de herbicidas. Aos 60 dias após a semeadura, colheu-se a parte aérea de todas as plantas, sendo semeada, nos mesmos vasos, Avena strigosa, utilizada como planta indicadora, para realização do bioensaio. Depois de 60 dias da semeadura da espécie bioindicadora, esta foi colhida, sendo avaliadas as seguintes características: altura de plantas, sintomas de toxicidade e biomassa seca da parte aérea das plantas. Até a dose de 0,5 kg ha-1 de tebuthiuron, a espécie que melhor fitorremediou esse herbicida no solo foi L. albus. Quando o solo foi tratado com 1,0 kg ha-1 de tebuthiuron, C. ensiformes foi a espécie que melhor fitorremediou o herbicida. Isso foi concluído com base na maior altura de plantas, biomassa seca da parte aérea e menor toxicidade de A. strigosa, quando foi cultivada em sucessão a essas plantas remediadoras. Nenhuma das espécies avaliadas cresceu em solo que recebeu a maior dose de tebuthiuron (1,5 kg ha-1.Phytoremediation of soil contaminated by organic compounds, including herbicides, is being widely investigated. The frequent use of tebuthiuron can cause serious environmental impacts such as long-term residual effect on soil and likely underground water contamination. Thus, this work aimed to evaluate the phytoremediation potential of seven plant species in soils treated with this herbicide. The experiment evaluated the following species: Cajanus cajan, Canavalia ensiformes, Dolichos lablab, Pannisetum glaucum, Estizolobium deeringianum, Estizolobium aterrimum and Lupinus albus, sown and cultivated for 60 days in vases treated with tebuthiuron at 0.0, 0.5, 1.0, and 1.5 kg ha-1. The control treatments were constituted by vases without plants, submitted to the same herbicide doses. Sixty days after sowing, the aerial part of all the plants was harvested and Avena strigosa was sown in the same vases for bioassay. Sixty days after it was sown, A. strigosa was harvested and the characteristics plant height, phytotoxicity symptoms and dry biomass of the aerial part of the plant were evaluated. Up to a tebuthiuron dose of 0.5 kg ha-1, L. albus presented the best phytoremediation results. When tebuthiuron was applied at 1.0 kg ha-1, C. ensiformes presented the best phytoremediation results. Such results were based on plant height, dry biomass of the aerial part and lower A. strigosa phytotoxicity when cultivated after these remediating plants. None of the species evaluated grew in soil receiving the highest dose of tebuthiuron (1.5 kg ha-1.

  14. Desenvolvimento de métodos voltamétricos para a quantificação de LSD utilizando-se o eletrodo de pasta de carbono modificado com complexo de base de Schiff

    OpenAIRE

    Maria Fernanda Muzetti Ribeiro

    2015-01-01

    Nos últimos anos, vários métodos eletroanalíticos foram desenvolvidos a fim de tornarem mais práticas e acessíveis às análises químicas de substâncias entorpecentes realizadas pela polícia científica. Com a sensibilidade e seletividade compatíveis com as dos métodos instrumentais convencionais, é a portabilidade da técnica eletroanalítica que se sobressai e tem apresentado grande potencial para tais aplicações. O uso de complexos metálicos com as bases de Schiff como modificadores do eletrodo...

  15. Estimativa da transpiração em cafeeiros utilizando-se sensores de dissipação térmica Estimation of transpiration in coffee crop using heat dissipation sensors

    Directory of Open Access Journals (Sweden)

    Jussálvia da S. Pimentel

    2010-02-01

    Full Text Available Alguns métodos são capazes de determinar diretamente a quantidade de água consumida por uma planta, entre eles o "método de dissipação de calor" ou método de Granier. Neste trabalho se propôs, como objetivo, construir e calibrar sensores de dissipação térmica, avaliar a transpiração em função da posição de inserção do sensor na planta (Norte, Sul, Leste ou Oeste e comparar os resultados com os elementos meteorológicos e a evapotranspiração de referência. Em 24 cafeeiros se instalaram sensores de dissipação térmica, adaptados de Granier (1985, em que o conjunto termopar e resistência foi inserido na agulha. Obteve-se a densidade de fluxo de seiva a partir da variação da diferença de temperatura entre as sondas e se acompanhou a transpiração, em função da transição entre os períodos diurno e noturno. O experimento foi avaliado em 3 períodos: antecedente à floração, na floração e no início da frutificação. Não houve diferença significativamente entre os ângulos de inserção para o fluxo de seiva. Quanto aos elementos meteorológicos, a radiação e a umidade relativa foram os fatores mais determinantes da transpiração obtendo-se, por análises de regressão coeficientes r² entre 0,84 e 0,80.Some methods are capable of directly determining the amount of water consumed by a plant, among them, the "heat dissipation method" or Granier method. This study aimed to: build and calibrate sensors of thermal dissipation; to evaluate the transpiration as a function of the position of insertion of the sensor in the plant (North, South, East or West and to compare the results with the meteorological elements and the evapotranspiration of reference. In 24 coffee plants, thermal dissipation sensors adapted from Granier (1985 were installed, where the whole thermocouple and resistance were inserted into the needle. Density of the sap flow was obtained from the variation of the difference in temperature between the probes and accompanied transpiration according to the transition between day and night periods. The experiment was evaluated during 3 periods: before flowering, during the flowering and at the beginning of fruiting. There was no significant difference between the angles of insertion to the sap flow. Regarding the meteorological elements, radiation and relative humidity were the most determinant factors in transpiration, obtained by analysis of regressions with, r² coefficients between 0.84 and 0.80.

  16. Avaliação de transplantes renais utilizando-se 99mTc-leucócitos mononucleares Evaluation of renal allografts using 99mTc-mononuclear leukocytes

    Directory of Open Access Journals (Sweden)

    Sergio Augusto Lopes de Souza

    2004-02-01

    Full Text Available A rejeição aguda do enxerto renal deve ser diagnosticada precocemente, uma vez que a reversibilidade da rejeição está relacionada com a rapidez na qual o tratamento é iniciado. Os objetivos deste estudo foram: 1 estabelecer um método quantitativo para avaliação da rejeição e necrose tubular aguda (NTA do rim transplantado; 2 determinar o papel em potencial da cintilografia com leucócitos mononucleares marcados com tecnécio-99m no diagnóstico precoce da rejeição do rim transplantado e no diagnóstico diferencial da NTA. Cento e sessenta estudos cintilográficos foram realizados no primeiro e no quinto dia pós-operatório em 80 pacientes transplantados. Células autólogas foram utilizadas para marcação. Imagens foram obtidas 30 minutos, 3 horas e 24 horas após injeção de 444 MBq (12 mCi das células marcadas. Houve captação anormal das células marcadas em 27 de 31 casos de rejeição e em seis de oito casos de NTA. Os resultados foram comparados com a clínica de cada paciente. Ultra-sonografias com Doppler detectaram 18 de 31 casos de rejeição. A sensibilidade e a especificidade para rejeição foram, respectivamente, de 87,1% e 100% para a cintilografia e 58,1% e 100% para a ultra-sonografia. Foram realizadas biópsias em oito pacientes, que mostraram sete rejeições e uma NTA. Os resultados sugerem que a cintilografia com leucócitos mononucleares marcados com tecnécio-99m pode ser útil no diagnóstico de rejeição e diagnóstico diferencial de NTA.Renal allograft acute rejection must be promptly diagnosed since its reversibility is related to the readiness in which treatment is initiated. The aim of this study was: 1 to establish a quantitative method to evaluate kidney rejection and acute tubular necrosis (ATN; 2 to assess the potential role of 99mTc-mononuclear leukocytes scintigraphy in the diagnosis of renal rejection and differential diagnosis of ATN. One hundred and sixty studies were performed in 80 renal transplant patients at the first and fifth day after transplantation. Autologous cells were used for labeling. Images were obtained at 30 minutes, 3 hours and 24 hours after intravenous administration of 444 MBq (12 mCi of labeled cells. There was abnormal labeled cells uptake in 27 of 31 cases of rejection and in 6 of 8 cases of ATN. The results of each patient were compared with clinical findings. Doppler scanning detected 18 of 31 cases of rejection. Rejection diagnosis sensitivity and specificity rates using scintigraphy were 87.1% and 100%, respectively, and 58.1% and 100%, respectively using ultrasound. Renal biopsy was performed in eight patients which demonstrated seven cases of rejection and one case of ATN. These results suggest that 99mTc-mononuclear leukocytes imaging may be useful in the early diagnosis of rejection and in the differential diagnosis of ATN.

  17. ANÁLISE MORFOLÓGICA E MICROBIOLÓGICA UTILIZANDO-SE DIFERENTES MÉTODOS DE PRESERVAÇÃO SOBRE A CAMADA MUSCULAR DO INTESTINO DELGADO DE CÃES

    Directory of Open Access Journals (Sweden)

    Luiz Antônio Franco da Silva

    2006-10-01

    Full Text Available Foram avaliadas 40 amostras da camada muscular do intestino delgado de cães, mantidas em diferentes soluções preservadoras, a saber – solução 1: glicerina a 98%;solução 2: tintura alcóolica de tiomersal 1:1000; solução 3:solução fisiológica 0,9% congelada a -16oC com antibiótico; solução 4: solução fisiológica 0,9% congelada a -16oC,solução 5: polivinilpirrolidona a 50%; solução 6: solução supersaturada de açúcar na concentração de 300%, e solução 7: solução supersaturada de açúcar na concentração de 300% com antibiótico. As amostras foram mantidas nos meios de preservação por 45 dias e após esse período submetidas à analise microbiológica e avaliadas pelos aspectos macroscópicos, histológico e pelo analisador de imagens HL Image 97++. Não houve crescimento de microorganismo em nenhum dos meios estudados. A glicerina a 98% e a solução de açúcar supersaturada na concentração de 300%,com e sem antibiótico, foram os melhores preservadores, por manterem a integridade celular. PALAVRAS-CHAVE: Integridade celular, preservação, análise microbiológica.

  18. A new approach for the programing of equipment and transmission lines shut-down, using probabilistic techniques; Um novo enfoque para a programacao de desligamento de linhas de transmissao e equipamentos, utilizando-se tecnicas probabilisticas

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Paulo; Haraguchi, Kazuo [ELETROBRAS, Rio de Janeiro, RJ (Brazil); Mello, Joao C. de [Centro de Pesquisas em Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil); Zani, Cesar Ribeiro [FURNAS Centrais Eletricas S.A., Rio de Janeiro, RJ (Brazil); Cafe, Fernando F. [Companhia Energetica de Minas Gerais (CEMIG), Belo Horizonte, MG (Brazil); Botelho, Manoel J.; Leite, Sergio R. [ELETROSUL, Curitiba, PR (Brazil)

    1995-12-31

    The maintenance of elements of an electric power transmission system such as: electric cables; transformers; etc, results in alterations of the electric power transmission line and may even cause operation restrictions which, in the worst situation, means shutting down the supply. In order to improve the shutting down programing a probabilistic methodology was developed. This work presents such methodology 2 tabs.; 8 refs.

  19. Identificação de pigmentos naturais de espécies vegetais utilizando-se cromatografia em papel Identification of natural pigments from vegetal species using paper chromatography

    Directory of Open Access Journals (Sweden)

    Fabiano Okumura

    2002-07-01

    Full Text Available The use of natural dyes to demonstrate principles of paper chromatography is proposed. Extraction of the coloring compounds were performed in order to obtain the aglycone form of the anthocyanins present in the crude extracts. Separations were carried out on chromatographic paper with BAW (butanol/acetic acid/water as mobile phase and the results compared with literature data. The crude extracts were obtained from Tibouchina granulosa, Rododhendron simsii, Impatiens walleriana flowers which are wildely found in Brazil and Phaseolus vulgaris L. grains skin which is the principal ingredient of the world famous "feijoada". Such species were chosen in order to attract the students attention since they are present in their quotidian, in agreement with the new proposals for Brazilian education.

  20. Optimization of the isotopic analysis of UF{sub 6} by quadrupole mass spectrometry technique; Otimizacao da analise isotopica de UF{sub 6} utilizando-se a tecnica de espectrometria de massas por quadrupolo

    Energy Technology Data Exchange (ETDEWEB)

    Porto, Peterson

    2006-07-01

    In the present work a procedure for determination of the isotopic ratio {sup 238}U/{sup 235}U in UF{sub 6} samples was established using a quadrupole mass spectrometer with ionization by electron impact and ion detection by Faraday cup or electron multiplier. For this, the following items were optimized in the spectrometer: the parameters in the ion source that provided the most intense peak, with good shape, for the corresponding mass of the most abundant isotope; the resolution that reduced the non linear effects and the number of analytic cycles that reduced the uncertainty in the results. The measurement process was characterized with respect to the effects of mass discrimination, linearity and memory effect. The mass discrimination showed to be linearly dependent of the sample pressure in the batch volume, for the pressure ranges from 0.15 to 0.30 mbar and from 0.30 to 0.40 mbar. The spectrometer was shown linear in the measurement of isotopic ratios between 0.005 and 0.045. The memory factor for the ion source and for the introduction system were, respectively, 1.000 {+-} 0.001 and 1.003 {+-} 0.003; the first one can be ignored, the second one can be eliminated by washing the batch volume with the new sample. A methodology for routine analysis of UF{sub 6} samples and the determination of the uncertainties were set up in details as well. (author)

  1. Thermal comfort in reduced models of broilers' houses, under different types of roofing materials Conforto térmico em modelos reduzidos de galpões para frangos de corte, utilizando-se de diferentes tipos de coberturas

    Directory of Open Access Journals (Sweden)

    Eduardo A. de Almeida

    2013-02-01

    Full Text Available The research was developed to evaluate the use of different types of roofing materials regularly used in poultry houses. Measurements of thermal comfort were made through the use of techniques such as the Black Globe and Humidity Index (BGHI, the Thermal Heat Load (THL and Enthalpy (H. Conducted in the State University of Goiás, during the months of April and May, 2011, the experiment was composed of five different treatments: AC - Asbestos cement tiles, BA -Bamboo tiles, BAP - Bamboo tiles painted in white, FB -Vegetable fiber tiles and bitumen, FBP -Vegetable fiber tiles and bitumen painted in white. The experiment consisted in 15 repetitions, which were considered the different days of measurements taken. Throughout the studied period, the time of the day considered the least comfortable was the one observed at 2:00pm, and the coverage of vegetable fiber and bitumen showed the highest value of BGHI (84.1 when compared to other types of coverage, characterizing a situation of lower thermal comfort, and no difference was found for THL and H on treatments in the studied region.Esta pesquisa foi conduzida com o objetivo de avaliar diferentes tipos de coberturas em instalações para aves, por meio do Índice de Temperatura de Globo Negro e Umidade (ITGU, Carga Térmica de Radiação (CTR e Entalpia (H. O experimento foi conduzido na Universidade Estadual de Goiás, entre os meses de abril e maio de 2011, sendo composto por cinco tratamentos (coberturas: CA -Telha de cimento-amianto; BA -Telha de bambu; BAP -Telha de bambu pintada de branco; FB -Telha de fibra vegetal e betume; FBP -Telha de fibra vegetal e betume pintada de branco, com 15 repetições, sendo as repetições os dias de medição. Dentre os horários estudados, o considerado menos confortável foi às 14h, sendo que a cobertura de fibra vegetal e betume foi a que apresentou maior valor de ITGU (84,1 quando comparada às demais coberturas, caracterizando uma situação de menor conforto térmico, não sendo observada diferença para CTR e H entre os tratamentos na região estudada.

  2. Avaliação do desempenho na pós-desmama para uma população bovina multirracial Aberdeen Angus x Nelore utilizando-se diferentes modelos genéticos

    Directory of Open Access Journals (Sweden)

    J.S Lopes

    2010-12-01

    Full Text Available Com o objetivo de testar modelos genéticos alternativos ao aditivo-dominante em populações multirraciais, foram utilizadas informações do peso ao sobreano (PS de 35.931 novilhos, filhos de 752 touros e 30.535 vacas das raças Aberdeen Angus (A e Nelore (N e de diversos grupos genéticos possíveis por meio do cruzamento entre elas. Foram testados cinco diferentes modelos (M genéticos: o M1 continha o efeito genético fixo aditivo direto (AD, heterozigótico direto (HD, epistático direto (ED e aditivo-conjunto direto (ACD; o M2, igual ao M1, menos o efeito ACD; o M3, igual ao M1, menos o efeito ED; o M4, igual ao M1, menos os efeitos ED e ACD; e o M5, igual ao M1, menos os efeitos HD, ED e ACD. Os modelos foram submetidos a três métodos de análise diferentes: método dos quadrados mínimos (MQM, regressão de cumeeira (RC e máxima verossimilhança restrita (REML. O método de RC produziu estimativas de coeficientes com magnitudes e sinais explicados biologicamente. As estimativas dos efeitos, das (covariâncias, dos parâmetros e dos valores genéticos diferiram entre os modelos, indicando a importância da correta escolha do modelo de análise, devendo-se ter conhecimento prévio do fenômeno estudado e sua interpretação biológica e sempre preceder à escolha de um modelo de análise genética multirracial o estudo da relação existente entre as variáveis independentes. Importantes efeitos adicionais ao efeito AD foram acrescentados pelas inclusões dos efeitos HD e ED aos modelos de análise. A notação matemática dos efeitos ACD, aplicada atualmente na literatura e testada neste estudo, não foi capaz de explicar a complementaridade entre raças como esperado, havendo problemas com casos de multicolinearidade entre os efeitos estudados

  3. Nefrectomia parcial laparoscópica em ratos : técnica e efeitos morfológicos utilizando-se bisturi elétrico e bisturi harmônico /

    OpenAIRE

    Meyer, Fernando

    2003-01-01

    Orientador: Sérgio Ossamu Ioshii Inclui apęndice Tese (doutorado) - Universidade Federal do Paraná, Setor de Cięncias da Saúde, Programa de Pós-Graduaçăo em Clínica Cirúrgica. Defesa: Curitiba, 2003 Inclui bibliografia e anexos

  4. 自锁托槽矫正器对正畸患者牙周健康影响的临床研究%Effects of self-locking orthodontic bracket on the periodontal health of orthodontic patients

    Institute of Scientific and Technical Information of China (English)

    陈栋梁

    2015-01-01

    Objective To investigate the effects of self-locking orthodontic bracket on the periodontal health of orthodontic patients.Methods Study group was given self-ligating bracket appliance therapy,control group received conventional treatment ligation style brackets.Periodontal health followup of malocclusion deformity patients before and after treatment was recorded.Results After treatment,GI,PLI,SBI scores were changed,but that of the study group was significantly lower than that of the control group ((P < 0.05).The patient satisfaction degree in study group was significantly higher than that of the control group(P < 0.05).Conclusions The use of self ligating appliance orthodontic treatment is conducive to the protection of patients with periodontal health,to obtain satisfactory outcome,guarantee the quality of life of patients,maintain good relationship between doctors and patients.%目的 探讨自锁托槽矫治器对正畸患者牙周健康的影响.方法 研究组给予自锁托槽矫治器治疗;对照组给予传统结扎式托槽治疗.记录两组错颌畸形患者治疗前后牙周健康随访情况.结果 两组患者治疗后GI、PLI、SBI评分均较治疗前有所变化,但研究组变化幅度明显低于对照组(P<0.05);研究组患者对治疗结果满意度显著高于对照组(P<0.05).结论 使用自锁托槽矫治器进行正畸治疗有利于保护患者牙周组织健康,使其获得满意预后,保障患者生活质量,维持良好的医患关系.

  5. Study of opening bite in treatment of straight wire bracket change%利用直丝弓托槽改换打开咬合方法初探

    Institute of Scientific and Technical Information of China (English)

    孙轲; 单国章

    2016-01-01

    目的:观察利用直丝弓托槽改换打开咬合患者的牙齿改变,探讨该技术特点。方法7例Ⅱ类错患者均拔除4颗前磨牙,按照改换技术进行矫治,矫治前及打开咬合后行牙齿及X线头影测量分析。结果与矫治前相比,患者覆减少6.00 mm,拔牙间隙减少24.14 mm,上颌支抗磨牙近中移动仅为0.86 mm,差异有统计学意义( P<0.05)。结论直丝弓托槽改换利用口内支抗,快速打开咬合、减少拔牙间隙,结合细丝弓和直丝弓技术优点,可有效矫治Ⅱ类错患者。%Objective To evaluate the patient occlusional changes treated with change of the straight wire bracket technolo -gy.Methods Seven Class Ⅱ patients with bimaxillary or maxillary protrusion were selected .All the patients were four premolar extraction cases and treated with change the straight wire bracket technology .Cephalometric analysis was performed to evaluate the changes before and after treatment.Results After treatment,patient occlusion opened 6.00 mm,tooth clearance decreased 24.14 mm,and upper molars moved forward slightly;all the differences were statistically significant ( P<0.05 ) .Conclusion The anchorage control in change the straight wire bracket technology is effective .Under very light force ,the crown of anterior teeth tips distally and lingually quickly ,and the extraction space closes quickly.In the final stage,it is possible to achieve both desired root uprighting and crown torque .

  6. Effects of two erbium-doped yttrium aluminum garnet lasers and conventional treatments as composite surface abrasives on the shear bond strength of metal brackets bonded to composite resins

    Science.gov (United States)

    Sobouti, Farhad; Dadgar, Sepideh; Sanikhaatam, Zahra; Nateghian, Nazanin; Saravi, Mahdi Gholamrezaei

    2016-01-01

    Background: Bonding brackets to dental surfaces restored with composites are increasing. No studies to date have assessed the efficacy of laser irradiation in roughening of composite and the resulted shear bond strength (SBS) of the bonded bracket. We assessed, for the 1st time, the efficacy of two laser beams compared with conventional methods. Materials and Methods: Sixty-five discs of light-cured composite resin were stored in deionized distilled water for 7 days. They were divided into five groups of 12 plus a group of five for scanning electron microscopy (SEM): Bur-abrasion followed by phosphoric acid etching (bur-PA), hydrofluoric acid conditioning (HF), sandblasting, 3 W and 2 W erbium-doped yttrium aluminum garnet laser irradiation for 12 s. After bracket bonding, specimens were water-stored (24 h) and thermocycled (500 cycles), respectively. SBS was tested at 0.5 mm/min crosshead speed. The adhesive remnant index (ARI) was scored under ×10 magnification. SEM was carried out as well. Data were analyzed using analysis of variance (ANOVA), Kruskal–Wallis, Tukey, Dunn, one-sample t-test/Wilcoxon tests, and Weibull analysis (α =0.05). Results: The SBS values (megapascal) were bur-PA (11.07 ± 1.95), HF (19.70 ± 1.91), sandblasting (7.75 ± 1.10), laser 2 W (15.38 ± 1.38), and laser 3 W (20.74 ± 1.73) (compared to SBS = 6, all P = 0.000). These differed significantly (ANOVA P = 0.000) except HF versus 3 W laser (Tukey P > 0.05). ARI scores differed significantly (Kruskal–Wallis P = 0.000), with sandblasting and 2 W lasers having scores inclined to the higher end (safest debonding). Weibull analysis implied successful clinical outcome for all groups, except for sandblasting with borderline results. Conclusion: Considering its high efficacy and the lack of adverse effects bound with other methods, the 3 W laser irradiation is recommended for clinical usage. PMID:26998473

  7. Avaliação da resistência ao cisalhamento de braquetes da técnica lingual colados sobre superfície cerâmica Evaluation of shear strength of lingual brackets bonded to ceramic surfaces

    Directory of Open Access Journals (Sweden)

    Michele Balestrin Imakami

    2011-06-01

    Full Text Available OBJETIVO: avaliar a resistência ao cisalhamento de braquetes metálicos (American Orthodontics utilizados na técnica lingual, colados em facetas de cerâmica. MÉTODOS: foram utilizados 40 corpos de prova divididos em quatro grupos de 10, de acordo com o material de colagem e do preparo da porcelana: Grupo I -resina Sondhi Rapid-Set e ácido fluorídrico; Grupo II -resina Sondhi Rapid-Set e óxido de alumínio; Grupo III -resina Transbond XT e ácido fluorídrico; e Grupo IV -resina Transbond XT e óxido de alumínio. Previamente à colagem, os braquetes foram preparados com base de resina de carga pesada (Z-250 e as facetas de cerâmica receberam aplicação de silano. O teste de cisalhamento foi realizado por uma máquina de ensaios Kratos à uma velocidade de 0,5mm/min. RESULTADOS: os resultados obtidos foram analisados estatisticamente através do teste de Tukey (pOBJECTIVE: The aim of this study was to evaluate the shear strength of lingual metal brackets (American Orthodontics bonded to ceramic veneers. METHODS: A total of 40 specimens were divided into four groups of 10, according to bonding material and ceramics preparation: Group I -Sondhi Rapid-Set resin and Hydrofluoric acid, Group II -Sondhi Rapid-Set resin and aluminum oxide, Group III -Transbond XT resin and Hydrofluoric acid, and Group IV -Transbond XT resin and aluminum oxide. Prior to bonding, the brackets were prepared with heavy-duty resin base (Z-250 and the ceramic veneers were treated with silane. The shear test was conducted with a Kratos testing machine at a speed of 0.5 mm/min. RESULTS: The results were statistically analyzed by the Tukey test (p<0.05 and showed a statistically significant difference between groups I (2.77 MPa and IV (6.00 MPa, and between groups III (3.33 MPa and IV. CONCLUSION: In conclusion, the bonding of lingual brackets to ceramic surfaces exhibited greater shear strength when aluminum oxide was used in association with the two resins utilized in

  8. 粘贴含氟正畸托槽后菌斑和唾液中氟离子的变化%Fluoride levels in dental plaque and saliva following the bonding of fluoride-releasing orthodontic brackets

    Institute of Scientific and Technical Information of China (English)

    余哲; 白玉兴; 厉松

    2011-01-01

    Objective To measure the fluoride levels in dental plaque and saliva following the bonding of fluoride-releasing orthodontic brackets. Methods Fluoride ion-specific electrode was used to determine the fluoride concentrations in dental plaque and saliva of 10 volunteers who used the fluoride-releasing orthodontic brackets. The fluoride concentrations were then compared with baseline. Results The fluoride concentrations in dental plaque and saliva were significantly higher compared with base line. The higher fluoride levels lasted for 3 days in saliva and for 18 days in dental plaque. Conclusion The fluoride levels in dental plaque and saliva increased after the bonding of fluoride-releasing orthodontic brackets,which may play a role in preventing decalcification of enamel.%目的 测定粘贴含氟正畸托槽后,口腔内菌斑及唾液氟离子浓度的变化,探讨采用含氟正畸托槽预防牙釉质脱矿的意义.方法 选择10名志愿者,口腔内粘贴含氟正畸托槽.用离子选择性氟电极测定口腔内菌斑及唾液氟离子浓度,并与粘贴托槽前的基线水平相比较.结果 粘贴含氟正畸托槽后,菌斑及唾液中氟浓度均升高,唾液氟浓度持续3天高于基线水平,差异有统计学意义(P<0.05);菌斑氟浓度持续18天高于基线水平,差异有统计学意义(P<0.01).结论 粘贴含氟正畸托槽后,口腔内菌斑和唾液中的高氟浓度能维持一段时间,有可能起到一定的预防牙釉质脱矿的作用.

  9. Parametrization for the simulation of the Argon injection system in a steel furnace; Parametrizacao para simulacao do sistema de injecao de argonio em panela de aco

    Energy Technology Data Exchange (ETDEWEB)

    Dellaretti Filho, Osmario; Lourenco, Paulo T. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Escola de Engenharia

    1987-12-31

    It was performed a selection of variables which may be used for simulating of Argon injection in liquid steel through a cold model. Those variables were set in dimensionless group defined by Dimensional Analysis. Based on the Principle of Similarity some of these dimensionless groups were used to set parameters of the model. The conditions for transposing the results from the cold model to the real one were also discussed. (author). 31 refs., 1 tab.

  10. Influence of different silane coupling agents on shear bond strength of metal brackets to porcelain surface%不同偶联剂对烤瓷瓷面与金属托槽抗剪切力的影响

    Institute of Scientific and Technical Information of China (English)

    丁宏

    2015-01-01

    Objective To investigate the influence of different silane coupling agents to the shear bond strength of metal brackets bonded to porcelain surface. Methods 30 porcelain specimens were deglazed by water sandpaper and etched,rinsed with distilled water and dried before applying the silane primer.All specimens were divided randomly into 3 groups according to different silane coupling agents application,every group had 10 porcelain facets.30 metal brackets were bonded to ceramic specimens.All specimens were stored in artificial saliva bath at 37℃ for 24 hours.after brackets bonded for 60min,then the specimens were underwent shear testing with Instron universal testing machine. Results The shear bond strength of the groups treated with silane primer were higher than that without silane primer(P0.05).The groups treated without silane coupling agent showed lower porcelain fracture than the groups treated with silane coupling agent. Conclusions Silane coupling agent can improve the shear bond strength between metal brackets and porcelain surface.There was not any statistically significant in the shear bond strength between the group of one-mix silane coupling agent and the group of two-mix silane coupling agent.%目的:研究不同类型硅烷偶联剂对烤瓷瓷面与金属托槽之间抗剪切力的影响。方法:将30个烤瓷瓷面行水砂纸打磨去釉,HF酸蚀处理,根据硅烷偶联剂的不同随机分3组,将30个金属托槽粘结于烤瓷瓷面,托槽粘结60min后经37℃恒温人工唾液水浴孵化24h,使用Instron万能材料力学试验机测定样本抗剪切力。结果:使用硅烷偶联剂组抗剪切力比未使用硅烷偶联剂组大,差异有统计学意义(P<0.05);单组份和双组份硅烷偶联剂组之间抗剪切力比较,差异无统计学意义(P>0.05);未使用硅烷偶联剂组瓷面破损指数明显小于使用硅烷偶联剂组,差异有统计学意义(P<0.05)。结论:硅烷偶联剂能有

  11. Evaluation of enamel surface after bracket debonding and polishing Avaliação da superfície do esmalte dentário após a remoção do braquete e polimento

    Directory of Open Access Journals (Sweden)

    Lilian Maria Brisque Pignatta

    2012-08-01

    Full Text Available INTRODUCTION: Preserving the dental enamel structure during removal of orthodontic accessories is a clinician's obligation. Hence the search for an evidence based debonding protocol. OBJECTIVE: to evaluate and compare, by means of scanning electron microscopy (SEM, the effects of four different protocols of bracket debonding and subsequent polishing on enamel surface, and to propose a protocol that minimizes damage to enamel surface. METHODS: Twelve bovine permanent incisors were divided into four groups according to the instrument used for debonding and removal of the adhesive remnant. In groups 1 and 2, brackets were debonded with a straight debonding plier (Ormco Corp., Glendora, California, USA, and in groups 3 and 4, debonding was performed with the instrument Lift-Off (3M Unitek, Monrovia, California, USA. In groups 1 and 3, the adhesive remnant was removed using a long adhesive removing plier (Ormco Corp., Glendora, California, USA and in groups 2 and 4, residual adhesive was removed with a tungsten carbide bur (Beavers Dental at high-speed. After each stage of debonding and polishing, enamel surfaces were replicated and electron micrographs were obtained with 50 and 200X magnification. RESULTS: All four protocols of debonding and polishing caused enamel irregularities. CONCLUSION: Debonding brackets with straight debonding plier, removal of adhesive remnant with a tungsten carbide bur and polishing with pumice and rubber cup was found to be the protocol that caused less damage to enamel surface, therefore this protocol is suggested for debonding brackets.INTRODUÇÃO: a preservação da estrutura de esmalte após a remoção dos acessórios ortodônticos é obrigação do clínico. Portanto, procura-se um protocolo de descolagem com bases científicas. OBJETIVO: objetivou-se avaliar por microscopia eletrônica de varredura (MEV a influência de quatro protocolos de remoção de braquetes e polimento da superfície do esmalte e propor um

  12. 汽车驾驶舱横梁支架成形工艺分析与模具设计%Analysis of forming process and design of die for crossbeam-bracket of automobile cockpit

    Institute of Scientific and Technical Information of China (English)

    李志红; 罗志伟; 赵军

    2011-01-01

    根据汽车驾驶舱中某横梁支架的结构特点,进行了成形工艺分析,采用2副复合模完成支架的成形,通过在工件弯曲处压成形边翼增加工件的刚度,减少弯曲回弹.生产实践表明:生产的支架尺寸、形状均合符设计要求.%The forming process for a crossbeam-bracket in a cockpit was analyzed based on the product's structural characteristics. Two sets of compound die were developed for the product in which the side wings of the part were formed at the bent position that can increase the rigidity and reduce the bending springback.

  13. 港机专用橡胶拖令移动软电缆研制与安装敷设%Manufacturing and Installation of the Moving Soft Cable with Rubber Towing Bracket for Port Crane

    Institute of Scientific and Technical Information of China (English)

    赵爱林; 李永江

    2011-01-01

    In order to raise the working life and safety performance of the cable for port crane, a new high performance moving soft cable with towing bracket dedicated for port crane has been developed. This paper introduces technical performance, product design, production technology and key points for trial-producing. Also it introduces the installation of the cable, which could enlighten the cable users.%为提高港口用电缆的使用寿命和安全性能,开发了新型的高性能港机专用橡胶拖令移动软电缆。介绍了该电缆的技术性能、产品设计、生产工艺和试制要点,并介绍了该电缆的安装敷设,对电缆用户有一定的启迪。

  14. Knoop hardness of enamel and shear bond strength of brackets bonded with composite resin with and without fluoride Dureza Knoop do esmalte e resistência ao cisalhamento de braquetes colados com resina composta com e sem flúor

    Directory of Open Access Journals (Sweden)

    Silvia Amélia Scudeler Vedovello

    2012-08-01

    Full Text Available OBJECTIVE: The aim of this study was to evaluate the Knoop hardness of enamel, shear bond strength and failure pattern (adhesive, bracket/resin interface or mixed after bonding and debonding brackets, using resin composite with fluoride (Ortho Lite Cure, Ortho Source® and without fluoride (Orthobond, Morelli®. METHODS: Fragments (6 mm x 6 mm of 40 bovine incisor crowns were embedded in acrylic self-polymerizing resin. The Knoop hardness measurements were performed before and after bonding metal brackets. The specimens were divided into two groups, according to composite resin: with fluoride (Ortho Lite Cure, Ortho Source® and without fluoride (Orthobond, Morelli®. After bonding, the specimens were submitted to demineralization and remineralization cycling for 14 days. Shear bond strength testing was performed in a universal test machine (EMIC, at 5 mm/min crosshead speed. RESULTS: There was no significant difference in shear bond strength between Groups I and II. After demineralization and remineralization procedures (DE/RE, the specimens bonded with Ortho Lite Cure showed higher Knoop hardness than Orthobond. For both groups there was predominance of failure at bracket/resin interface. CONCLUSION: specimens bonded with fluoride resin composite showed higher microhardness after DE/RE cycling than those bonded with resin composite without fluoride, although no difference in shear bond strength was found.OBJETIVO: o propósito deste estudo foi avaliar a dureza Knoop do esmalte, resistência ao cisalhamento e padrão de falha (adesiva; interface braquete/resina; e mista após a colagem e descolagem de braquetes, utilizando uma resina composta com flúor (Ortho Lite Cure, Ortho Source® e uma sem flúor (Orthobond, Morelli®. MÉTODOS: fragmentos (6mm x 6mm de 40 coroas de incisivos bovinos foram embutidos em resina acrílica autopolimerizável. A dureza Knoop foi avaliada antes e após a colagem dos braquetes metálicos. Os corpos de prova

  15. Estudo comparativo de seis tipos de braquetes ortodônticos quanto à força de adesão A comparative study of six types of orthodontic brackets with regard to bond strength

    Directory of Open Access Journals (Sweden)

    Leonardo de Aquino Fleischmann

    2008-08-01

    Full Text Available INTRODUÇÃO: a realização de um diagnóstico acurado, assim como a correta seleção de materiais, especificamente dos braquetes, são requisitos importantes para o êxito da terapia ortodôntica. OBJETIVOS: investigar a influência de variados tipos de desenho da base de braquetes na força de adesão. METODOLOGIA: seis modelos foram avaliados mediante ensaio de cisalhamento - Discovery (Dentaurum - metálico com retenções por laser e 13,12mm² de área da base; Monobloc (Morelli - metálico em corpo único com protuberâncias e 10,22mm² de área; Edgewise Standard (Ortho Organizers - metálico com base MIM (Metal Injection Molding e 12,02mm² de área; Illusion Plus (Ortho Organizers - porcelana com sulcos de retenção e 13,49mm² de área; Composite (Morelli - policarbonato com protuberâncias para retenção mecânica e 14,68mm² de área; e Edgewise Standard (Morelli - metálico com tela de retenção e 14,31mm² de área. Os braquetes foram colados em dentes bovinos (incisivos com o sistema adesivo Fill Magic Ortodôntico (Vigodent, para a realização do teste. O ensaio foi executado em uma máquina de ensaios universal (EMIC, e a força de adesão foi computada, no momento da cisão, pelo software TESC, versão 3.01, medida em Newtons (N e em Megapascal (Mpa. RESULTADOS E CONCLUSÕES: não houve diferença estatística entre os braquetes testados, sendo que o grupo que apresentou a maior média de força de adesão foi o Discovery com 10,12Mpa.INTRODUCTION: An accurate diagnosis as well as the correct selection of materials, brackets in particular, are important pre-requisites for success in orthodontic therapy. AIM: The aim of this study was to examine the influence of various brackets-base designs on bond strength. METHODS: Six models were evaluated by a test of sheer bond strength: Discovery (Dentaurum - metallic with laser grooves and 13.12mm² of base area; Monobloc (Morelli - metallic one-piece with raised bumps and 10.22mm

  16. Application of Bowl Bracket in TLEMECEN University Building Construction Project%探索研究碗扣支架在大学城房建项目中的应用

    Institute of Scientific and Technical Information of China (English)

    钱坤

    2014-01-01

    Scaffold bracket as Template support has the characteristics of safe, reliable, simple operation, high efficiency etc. In Algeria, large number of housing construction projects are rarely used this efficient support system. Since visited Zhejiang condominium project, the author inspired a lot, and found that there were a variety of ways to improve labor productivity of a project, in which how to look for breakthrough in technical fields was the key, and this way was the most powerful and most fundamental way to solve the problem. This article studied and explored the application of bowl bracket in TLEMCEN University City 5í1000 academic buildings construction project.%碗扣式脚手架用作模板支架具有安全可靠、操作简单、高功效等特点。而在阿尔及利亚众多的房屋建筑项目中却很少用到这种高效的支撑体系,自从参观了浙江城建公寓项目后深受启发,提高一个项目的劳动生产率有很多种途经,而如何在技术领域寻找突破口则是关键,而且这种途经也是解决问题的最有力最根本的办法。本文是就碗扣支架能否在TLEMCEN大学城5伊1000座教学楼房建项目中得以应用做一下探索研究。

  17. Bracket/wire play: what to expect from tipping prescription on pre-adjusted appliances Folga braquete/fio: o que esperar da prescrição para inclinação nos aparelhos pré-ajustados

    Directory of Open Access Journals (Sweden)

    Leopoldino Capelozza Filho

    2012-08-01

    Full Text Available INTRODUCTION: The opinion on the 'straight-wire' concept has been evolving since its origin, characterized by faithful followers or absolute skepticism. Currently, it seems reasonable to state that most professionals have a more realistic and critical viewpoint, with an attitude that reveals Orthodontics' maturity and greater knowledge on the technique. The most relevant criticisms refer to the impossibility of the both the Straight-Wire and the Standard systems to completely express the characteristics related to the brackets due to mechanical deficiencies, such as bracket/wire play. OBJECTIVES: A critical analysis of this relationship, which is unclear due to lack of studies, was the scope of this paper. METHODS: The compensatory treatment of two patients, using Capelozza's individualized brackets, works as the scenery for cephalometric evaluation of changes in incisor inclination produced by different dimensions of leveling archwires. RESULTS: The evaluation of these cases showed that, while the introduction of a 0.019 x 0.025-in stainless steel archwire in a 0.022 x 0.030-in slot did not produce significant changes in incisor inclination, the 0.021 x 0.025-in archwire was capable of changing it, mainly in mandibular incisors, and in the opposite direction to the compensation. CONCLUSION: Considering compensatory treatments, even when using an individualized prescription according to the malocclusion, the bracket/wire play seems to be a positive factor for malocclusion correction, without undesirable movements. Therefore, it seems reasonable to admit that, until a bracket system can have absolute individualization, the use of rectangular wires that still have a certain play with the bracket slot is advisable.INTRODUÇÃO: a opinião sobre o conceito Straight-Wire tem evoluído desde sua origem, caracterizada por seguidores fiéis ou ceticismo absoluto. Atualmente, parece razoável acreditar que a maioria dos profissionais tem uma visão mais

  18. Avaliação da superfície de braquetes de titânio após a aplicação de fluoreto de sódio Evaluation of titanium brackets surface after immersion in sodium fluoride

    Directory of Open Access Journals (Sweden)

    Luciane Macedo de Menezes

    2006-06-01

    Full Text Available OBJETIVO: avaliar o efeito da aplicação do fluoreto de sódio (NaF 1,23% sobre a superfície de braquetes de titânio e de aço inoxidável. METODOLOGIA: foram utilizados 15 braquetes de titânio, divididos em três grupos: A grupo controle, composto por braquetes não submetidos a qualquer tipo de tratamento; B braquetes imersos por 60 segundos em fluoreto de sódio e lavados com 20ml de água destilada por trinta segundos; C braquetes imersos por 60 segundos em fluoreto de sódio e posteriormente submetidos à escovação por 15 segundos, sendo então lavados com 20ml de água destilada por trinta segundos. Para efeito comparativo, foram utilizados 15 braquetes de aço inoxidável, divididos em três grupos (Grupos A1, B1, C1 e submetidos aos mesmos procedimentos descritos. Todos os braquetes, antes e após o experimento, foram avaliados por inspeção visual e analisados ao microscópio eletrônico de varredura (Philips, modelo XL 30. RESULTADOS: a inspeção visual revelou uma mudança da coloração dos braquetes de titânio submetidos ao fluoreto de sódio (grupos B e C, apresentando-se escurecidos quando comparados aos acessórios do grupo A. Os braquetes de aço inoxidável não sofreram alteração cromática em nenhum dos grupos. CONCLUSÃO: através da análise por microscópio eletrônico de varredura, não foram constatadas alterações topográficas e químicas na superfície dos braquetes de titânio, assim como nos braquetes de aço inoxidável.AIM: to assess and compare the effects of fluoride (NaF 1.23% on titanium and stainless steel brackets. METHODS: Fifteen titanium brackets, divided in 3 groups were used: A control group (no treatment on its surface, B brackets immersed in NaF (60 seconds and washed with distilled water (30 seconds, C brackets with similar treatment to group B and submitted to brushing (15 seconds. Fifteen stainless steel brackets were used for comparative effects, divided in 3 groups, and submitted to

  19. Influência da secção transversa de fios ortodônticos na fricção superficial de braquetes autoligados Influence of the cross-section of orthodontic wires on the surface friction of self-ligating brackets

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    Roberta Buzzoni

    2011-08-01

    Full Text Available OBJETIVO: o objetivo do presente trabalho foi determinar a força de atrito estático entre braquetes de aço inoxidável autoligados com sistema de fechamento resiliente e fios ortodônticos redondos e retangulares do mesmo material. MÉTODOS: empregaram-se 30 braquetes referentes aos caninos superiores divididos em 6 grupos formados por braquetes autoligados Smartclip, In-Ovation R e convencionais Gemini amarrados com ligaduras elásticas. A hipótese testada neste trabalho foi quanto à possibilidade dos braquetes autoligados ativos serem suscetíveis à elevação da força de atrito com o aumento e alteração da secção transversal dos fios ortodônticos. Os ensaios foram realizados com tração de 30s em fios de aço inoxidável 0,020" e 0,019"X0,025" na máquina de ensaios Emic DL 10000, com uma célula de carga de 20 newtons. Cada conjunto braquete/fio foi responsável pela geração de quatro corpos de prova, totalizando 120 leituras. As comparações entre as médias foram realizadas através da Análise de Variância (one way ANOVA com correções pelo coeficiente de Bonferroni. RESULTADOS E CONCLUSÃO: os braquetes autoligados apresentaram maior força de atrito do que os braquetes convencionais amarrados com ligaduras elásticas. O grupo Smartclip foi o mais efetivo no controle do atrito (pOBJECTIVES: The purpose of this study was to assess the surface friction produced by self-ligating stainless steel brackets equipped with a resilient closure system and compare the friction generated during traction of round and rectangular orthodontic wires made from the same material. METHODS: Thirty maxillary canine brackets were divided into six groups comprising SmartClip and In-Ovation R self-ligating brackets, and conventional Gemini brackets tied with elastomeric ligatures. This investigation tested the hypothesis that self-ligating brackets are susceptible to increases in friction that are commensurate with increases and changes in the

  20. 不同处理方法对树脂面与托槽粘接强度的影响%Effects of different surface treatments on shear bonding strength between brackets and resin veneers

    Institute of Scientific and Technical Information of China (English)

    陈湘涛; 朱红; 梁凤林; 陈琳

    2009-01-01

    背景:树脂表面不同处理方法对金属托槽和树脂面的粘接强度可能有直接影响.目的:观察不同表面处理方法对金属托槽与光固化复合树脂修复体粘接抗剪切强度的影响.设计、时间及地点:对比观察实验,于2006-05/2007-04佳木斯大学口腔生物材料实验室完成.材料:制作20个双面充光固化复合树脂的长方块,共计40个树脂面,随机分为乙醇组、打磨组、酸蚀组、酸蚀+硅烷组,每组10个树脂面.方法:乙醇组:用蘸有体积分数为75%乙醇溶液的棉球擦拭树脂面,自然晾干.打磨组:使用钨钢麻花钻打磨树脂面中央使粘接面粗糙,打磨面积稍大于托槽底面积,用无油水气枪冲洗15 s,吹干.酸蚀组:9.6%氢氟酸酸蚀树脂面2 min,酸蚀面积稍大于托槽底面积,蒸馏水冲洗20 s,吹干.酸蚀+硅烷组:9.6%氢氟酸酸蚀处理同上,再在酸蚀的树脂面上均匀涂布一层硅烷偶联剂.在处理过的树脂面上均匀涂布一薄层光固化复合树脂底胶光固化灯照射20 s,将适量复合树脂置于托槽底部,以均匀适当的压力将托槽就位去除托槽周围多余的树脂,用光固化灯从托槽的近远中方向分别照射40 s使其固化粘接.主要观察指标:所有样品储存在37℃水中24 h后,5~55℃冷热循500次.将样品置于电子万能试验机下进行抗剪切强度的测试.并在10倍放大镜下观察树脂面破坏情况.结果:打磨组、酸蚀+硅烷组的抗剪切强度明显高于乙醇组和酸蚀组(P0.05).结论:氢氟酸酸蚀+硅烷偶联剂联合使用可提高金属托槽与光固化复合树脂修复体粘接的抗剪切强度,硅烷偶联剂的使用增加了托槽与树脂面的粘接强度.%BACKGROUND: Surface preparation of resin can directly influence the shear strength of orthodontic brackets bonded to resin surface.OBJECJIME: To compare the effects of various surface treatments on the shear bonding strength between metal brackets and resin

  1. Avaliação do atrito em braquetes autoligáveis submetidos à mecânica de deslizamento: um estudo in vitro Evaluation of friction in self-ligating brackets subjected to sliding mechanics: an in vitro study

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    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

  2. CURATIVE EFFICACY OF NON-BRACKET ORTHODONTIC TECHNIQUE VERSUS FIXED ORTHODONTIC TECHNIQUE%无托槽隐形矫治技术与固定矫治技术的临床疗效分析

    Institute of Scientific and Technical Information of China (English)

    周沛玲; 杨永平; 蔡嘉喜; 周腾田; 黄丹丹; 温志新; 何志亮; 何剑玲

    2015-01-01

    目的:分析无托槽隐形矫治技术与固定矫治技术的临床疗效。方法随机选自2012年8月~2014年8月本院收治的牙齿正畸患者86例,随机分为两组,各43例,对照组予固定矫治技术,研究组予无托槽隐形矫治技术,分析两组的临床效果。结果研究组倾斜牙矫正、转位牙扭正与治疗完成时间均短于对照组,差异具有统计学意义(p<0.05)。对照组除龈沟探诊深度无明显变化外,其他各项指数均明显增加(p<0.05)。两组治疗前各项牙周指数无明显差异,治疗后研究组菌斑指数明显低于对照组(p<0.05),其他指数相比无明显差异。结论相较于固定矫治技术,无托槽隐形矫治技术具有较高正畸效率,且其对患者牙周健康影响较小,值得临床推广应用。%Objective To analyze the clinical efficacy of non -bracket orthodontic technique versus fixed orthodontic tech-nique.Methods 86 cases receiving orthodontics in our hospital from August 2012 to August 2014 were selected.They were random-ly divided into two groups, each with 43 cases.The control group was treated with fixed orthodontic technique , whereas the study group was treated with non-bracket technique.The clinical curative effects of the two groups were analyzed .Results The time of correction of inclined teeth and transpositioned teeth and completed treatment time in the study group were shorter than those in the control group, with significant difference (p<0.05).The gingival sulcus and probing depth in the control group showed no obvious changes, but other indexes were significantly increased (p<0.05).And each periodontal index showed no significant difference be-tween the two groups before treatment.But after treatment, the plaque index of the study group was significantly lower than that in the control group (p<0.05).There were no significant differences in the other indexes between the two groups

  3. 胫骨粉碎性骨折的微创内固定支架固定疗效分析%Tibial comminuted fracture of minimally invasive internal ifxation bracket curative effect analysis

    Institute of Scientific and Technical Information of China (English)

    智建勋

    2015-01-01

    ABSTRACT:Objective To observe the tibia comminuted fracture of minimally invasive internal fixation bracket of technology in the treatment of comminuted fracture curative effect, to explore the surgical technique and advantages. Methods From 2009 to 2013 treated 114 cases of tibial comminuted fracture patients were randomly divided into fixed stent technology of minimally invasive internal fixation treatment group (observation group) and traditional open reduction and internal fixation group (control group), each group of 57 cases, compared two groups of clinical curative effect. Results Follow-up for 3~12 months, an average of eight months, minimally invasive internal fixation bracket (observation group) technology treatment, fracture had 1 case to heal, the others all healing. the rate of good clinical curative effect was 96.3%. traditional open reduction and internal fixation treatment (control group), the healing of 51 patients, 6 cases were treated. 2 cases of patients with postoperative incision surrounding skin necrosis, osteomyelitis in 1 case , Clinical curative effect was 62.7%, the rate of good curative effect of two groups of patients and the difference between the average healing time was statistically significant (P <0.05). Conclusion Tibial comminuted fracture bracket technology of minimally invasive internal fixation treatment of fracture is a kind of safety, less injury, high fracture healing rate, fewer complications, and the minimally invasive treatment of fixed and reliable.%目的:观察胫骨粉碎性骨折的微创内固定支架固定技术治疗粉碎性骨折的临床疗效,探讨该手术的技巧、优点。方法将2009至2013年间收治的114例胫骨粉碎性骨折患者随机分为微创内固定支架固定技术治疗组(观察组)和传统切开复位内固定组(对照组),每组各57例,比较两组临床疗效。结果均获3~12个月随访,平均8个月,微创内固定支架固定技术

  4. O efeito do jateamento do esmalte na força de adesão na colagem de braquetes The effect of air abrasion in enamel adhesion of orthodontic bracket

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    Carla D'Agostini Derech

    2008-06-01

    Full Text Available OBJETIVO: o propósito deste estudo in vitro foi avaliar o efeito do jateamento com óxido de alumínio na adesão de braquetes ortodônticos e compará-lo à tradicional técnica de condicionamento ácido do esmalte. METODOLOGIA: foram utilizados 80 dentes bovinos distribuídos aleatoriamente entre quatro grupos, sendo que a superfície do esmalte foi tratada da seguinte maneira: grupo 1 (somente jateamento com óxido de alumínio, grupo 2 (profilaxia com pedra-pomes e condicionamento com ácido, grupo 3 (jateamento com óxido de alumínio e condicionamento ácido e grupo 4 (somente condicionamento ácido. Após, foi aplicado sistema adesivo e o braquete colado com resina. Os corpos-de-prova foram submetidos ao teste de cisalhamento e análise do IAR. Aos resultados foram aplicados o teste de variância múltipla (ANOVA e a comparação entre pares (Tukey. Para a análise do IAR foi aplicado o teste Qui-quadrado. RESULTADOS: o grupo 1 apresentou a menor resistência ao cisalhamento (3,6MPa e o 3 a maior (13,27MPa. A análise Qui-quadrado do IAR demonstrou que o tratamento da superfície do esmalte tem influência sobre a quantidade de remanescente de resina sobre o esmalte e os grupos 3 e 4 apresentaram a maior quantidade de resina aderida. CONCLUSÕES: o jateamento de óxido de alumínio não deve ser o único procedimento utilizado no preparo da superfície do esmalte na colagem de braquetes, porém, quando associado ao condicionamento ácido, mostrou-se eficaz no aumento da retenção entre esmalte e resina. Novos estudos são necessários visando menor dano do esmalte e adesão satisfatória.AIM: The purpose of this study in vitro was to evaluate the effect of the air abrasion with Al-oxide in the adhesion of orthodontic brackets and compare with traditional technique of acid conditioning of the enamel. METHODS: Eighty bovine teeth distributed randomly between four groups had been used and the surface of the enamel was prepared in the

  5. Avaliação da superfície da porcelana após a descolagem de braquetes ortodônticos Porcelain surface evaluation after debonding of orthodontic brackets

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    André Moreira Mattos

    2006-10-01

    Full Text Available OBJETIVO: o objetivo deste trabalho foi avaliar a influência do tempo de condicionamento ácido em superfície de porcelana e o estado desta após a descolagem de braquetes ortodônticos. METODOLOGIA: foram utilizadas 20 amostras de porcelana feldspática para esmalte (Duceram-LFC divididas em 2 grupos de acordo com o tempo de condicionamento com ácido fluorídico 10% (15 segundos e 1 minuto. Após o ataque ácido, foi aplicado silano (3M Scotchbond, adesivo resinoso (Optibond Solo Plus e resina (Fill Magic nestas superfícies. A descolagem foi realizada através de força de cisalhamento numa máquina universal de ensaios (DL 500 - EMIC calibrada com velocidade fixa de 0,5mm/minuto. O índice do adesivo remanescente (ARI nas superfícies cerâmicas e o estado destas após a remoção dos braquetes foram avaliados através de fotos digitais. RESULTADOS: no grupo 15 segundos, a força de adesão média foi de 3,63MPa, significantemente inferior à do grupo 1 minuto, que foi de 7,18MPa (pAIM: the aim of this study was to evaluate the influence of acid conditioning time in porcelain surface and its characteristics after debonding of orthodontic brackets. METHODS: twenty samples of feldspathic porcelain for enamel (Duceram-LFC were divided in 2 groups according with the amount of time of acid conditioning with hydrofluoric acid 10% (15 seconds and 1 minute. After acid etching, it was applied silane (3M Scotchbond, adhesive (Optibond Solo Plus and resin (Fill Magic in these surfaces. The debonding was done with shear strength through a universal testing machine (DL 500 - EMIC calibrated with a fixed speed of 0.5mm/minute. The adhesive remnant index (ARI in the porcelain surfaces and their characteristics after removal of the brackets were evaluated through digital pictures. RESULTS: in the 15 seconds group, the mean bond strength was 3.63Mpa, significantly lower than the 1 minute group, that was 7.18Mpa (p<0.0001. All fractures during debonding

  6. Analysis of Remote Weapon Station Bracket Stiffness,Strength and Fatigue Life Based on Virtual Prototype%基于虚拟样机的遥控武器站托架刚强度与疲劳寿命分析

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    毛保全; 梁博巍; 宋鹏

    2015-01-01

    Aiming at the practical problem that remote weapon station bracket which in fire system is under high load and measuring difficulties,based on remote weapon station virtual prototype,we explored analy-sis method of remote weapon station bracket stiffness,strength and fatigue life,and practiced it on a cer-tain type of remote controlled weapon station bracket,finally we got key problems of the analysis of remote weapon station bracket stiffness,strength and fatigue life. The analysis method could provide the theory reference on other core component.%针对遥控武器站火力系统中托架承受载荷较强与测量困难的实际问题,在遥控武器站虚拟样机的基础上,研究了遥控武器站托架的刚强度与疲劳寿命的分析方法,并实践于某型遥控武器站托架,最终得到了遥控武器站刚强度与疲劳寿命分析时应注意的重点问题。提出了适用于武器站托架的分析方法。分析方法可为其他关重件的刚强度校核与寿命分析提供理论参考与借鉴。

  7. 散货船底部纵骨防倾肘板节点疲劳优化研究%Fatigue Optimization Research of the Bottom Longitudinal Connection Detail with Tripping Bracket for Bulk Carrier

    Institute of Scientific and Technical Information of China (English)

    潘希颖

    2014-01-01

    A serial of connection details are researched for rising fatigue life of bottom longitudinal connection at tripping brackets under CSR ( BC) rule.The comparing of the stress concentration factors between them is applied by FEM analysis . Some of cutting details are proved to be very effective for rising fatigue life .The corresponding geometric stress concentration fac-tors are provided for these cuttings based on CSR ( BC) fatigue simplified calculation method .%为了提高CSR( BC)规范下散货船底部纵骨在防倾肘板连接处的疲劳寿命,采用有限元法比较几种不同切口形式在热点处的应力集中系数,确定其中有效的几种形式,使用共同规范的直接计算法予以证明,为便于使用,针对这些切口形式给出在CSR( BC)简化计算法中可以参照使用的系数。

  8. Treating tibia and fibula fracture in older children by Meng bracket combined with TEN%孟氏架结合TEN治疗大龄儿童胫腓骨骨折

    Institute of Scientific and Technical Information of China (English)

    陈王; 李铭雄; 吴天然; 叶若凡

    2014-01-01

    Objective:To evaluate the clinical efficacy of Meng bracket combined with TEN on treating tibia and fibula fracture in older children. Methods:Follow-up of 18 cases, Observed therapeutic effect. Results: After surgery, the use of Johner-Wruhs evaluation criteria, excellent in 16 cases, good in 2 cases, medium 0 cases, 0 poor. Conclusion:This therapy compliance with the biological fixation principles, simple operation, stable fixation, less trauma, fracture heal quickly good functional recovery, fewer complications, is an effective therapy for older children tibia and fibula fractures.%目的:评价孟氏架结合TEN治疗大龄儿童胫腓骨骨折的临床疗效。方法:随访该疗法治疗的胫腓骨骨折患者18例,观察其治疗效果。结果:术后采用Johner-Wruhs评价标准,优16例,良2例,中0例,差0例。结论:本疗法符合生物学固定原则,具有操作简单、固定牢靠、创伤小、骨折愈合快、功能恢复好、并发症少等优点,是治疗大龄儿童胫腓骨骨折的有效疗法之一。

  9. Comparative study on the apical root resorption between self-ligating and conventional brackets in extraction patients%自锁矫治与传统矫治对牙根吸收的影响

    Institute of Scientific and Technical Information of China (English)

    刘新强; 孙晓蕾; 杨茜; 范存晖; 陈秀娟

    2012-01-01

    PURPOSE: To explore whether orthodontic light force with self-ligating brackets.oan reduce the amount of external apical root resorption (EARR). METHODS: Thirty patients with Class Ⅰ or Ⅱ crowding malocclusion were selected. Four first premolars of all patients were extracted in orthodontic treatment. 15 patients were treated with self-ligating brackets (Damon 3MX) and 15 patients with conventional ligation brackets, respectively. Patients in two groups were comparable, in gender, age, crowded degree and malocclusion classification at the commencement of treatment. EARR of the maxillary and mandible incisors was evaluated on panoramic radiographs and models taken before and after treatment, and measured in millimeters. Student's t test was performed using SPSS19.0 software package. RESULTS: Overall, no difference was found in the amount of EARR between the two groups. The amount of EARR in maxillary central incisor was (2.05±1.51) mm in Damon group and (2.08 ±1.21) mm in conventional group (P=0.973>0.05); (1.77± 1.01) mm in maxillary lateral incisor in Damon group and (1.91±1.59) mm in conventional group(P=0.848>0.05); (2.06± 1.62) mm in mandibular central incisor in Damon group and (1.98±1.50) mm in conventional group (P=0.926>0.05); (1.94±1.45) mm in mandibular lateral incisor in Damon group and (1.84+1.17) mm in conventional group(P=0.888>0.05). CONCLUSION: No difference should be expected for root resorption between self-ligating and conventional brackets in orthodontic extraction treatment.%目的:探讨自锁托槽轻力矫治是否可以减轻对牙根的吸收.方法:选取临床治疗的安氏Ⅰ、Ⅱ类拥挤并拔除4颗第一前磨牙病例30例,分为2组.其中,15例使用Damon 3MX自锁托槽矫治(自锁组),15例使用传统结扎式直丝托槽矫治(结扎组).2组资料矫治前在性别、年龄、拥挤度及错(牙合)类型等指标上具有可比性.通过矫治前、后的模型及全口曲面体层片,测量计算2组矫治

  10. Lightweight Design of Balancing Suspension Bracket Based on Casting Defects and Structure Strength CAE%基于铸造缺陷和结构强度CAE的平衡悬架支架轻量化设计

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    张建振; 吴晓涛; 刘兆英; 常连霞; 朱明

    2014-01-01

    以节能减排为目的,以平衡悬架支架为研究对象进行轻量化设计。运用面向制造与装配的方法,借助铸造模拟MAGMA和结构优化及分析工具(OPTISTRUCT、ABAQUS)进行设计,使产品质量减轻40%,安全系数提高25%,成本降低5%。经台架试验验证了该轻量化方法的可行性,同时产品质量得到改善,开发周期也相应缩短。%For the purpose of energy saving and emission reduction, lightweight design is carried out for balanced suspension bracket. Using the method named DFMA ( Design for Manufacturing and Assembly), with the aid of casting simulation tool MAGMA, structure optimization tool OPTISTRUCT and topology optimization tool ABAQUS, the final product is lightened by 40%, safety factor of which is increased by 25%, and cost is reduced by 5%. Data from bench test of proves feasibility of the lightweight design plan, meanwhile the product quality is improved and development time is shortened.

  11. 高硅钼涡轮壳支架的凝固模拟和铸造工艺研究%Research on Solidification Simulation and Casting Process for Turbine Housing Bracket of High-Si-Mo Ductile Iron

    Institute of Scientific and Technical Information of China (English)

    袁海; 王今胜; 高顺

    2012-01-01

    高硅钼涡轮壳支架结构类似于排气管.根据高硅钼球铁的技术要求,制定了合理的熔炼工艺参数,但在AMF造型线生产时,缩松导致的报废率很高.为了消除缩松缺陷实现大批量生产,提出了4种工艺改进方案,并用MAGMA软件对凝固过程进行模拟,最终确定的方案不但能解决缩松缺陷,还能简化工艺流程,提高生产效率.%The structure of turhine housing bracket was similar to an exhaust. According to the technical requirements of high silicon molybdenum ductile iron, the reasonable melting process parameters were drafted, but the shrinkage led to a low qualified rate when produced in AMF moulding line. In order to eliminate the shrinkage defects to achieve massive production, four kinds of process improvement program was presented, and their solidification processes were simulated by MAGMA software and the position of shrinkage was predicted. Finally the chosen scheme can eliminate the shrinkage defect, simplify process and improve production efficiency.

  12. Empower自锁托槽治疗安氏Ⅱ1拔牙病例的疗效评价%Clinical study of extraction treatment of Class H division Ⅰ malocclusion with Empower self-ligating brackets

    Institute of Scientific and Technical Information of China (English)

    陈析华; 华咏梅; 谢兴潜; 俞晓佳; 王健; 刘李明

    2013-01-01

    PURPOSE:To evaluate and compare the treatment efficiency of Empower interactive self-ligating brackets and traditional brackets in Class Ⅱ division Ⅰ extraction patients.METHODS:Forty patients with Class Ⅱ division Ⅰ malocclusion were randomly divided into 2 groups.Twenty patients received Empower self-ligating technique (group A) and the other 20 patients received MBT technique (group B).Four first premolars were extracted and without any other anchorage devices added in both groups.The duration of treatment,the number of visits and chair-side time were recorded.Cephalometric analysis was performed before and after treatment.The data was analyzed with SPSS 13.0 software package for paired t test.RESULTS:Treatment time and number of visits in group A were more than in group B,but there was no significant difference between the 2 groups.Chair-side time in group A reduced 151.15s on average compared with group B.Significant changes were observed in both groups after treatment.Upper and lower anterior teeth retracted and convex profile improved.U1-SN,U1-NA,L1-MP,L1-NB,UI-PTV,LI-PTV,UL-EP,LL-EP decreased.Significant differences were found in UM-PTV between the 2 groups (P<0.05).CONCLUSIONS:Compared with traditional brackets,Empower self-ligating brackets can save chair-side time,control anterior teeth torque and posterior teeth anchorage effectively,but can not reduce the treatment time or number of visits.Supported by Youth Research Project of Shanghai Municipal Health Bureau(2010Y155).%目的:初步评价并比较Empower互动式自锁托槽和传统托槽矫治安氏Ⅱ1拔牙病例的疗效.方法:选择40例安氏Ⅱ类Ⅰ分类错(牙合)畸形患者,随机分为A、B2组.A组20例,使用Empower自锁托槽矫治技术;B组20例,使用MBT矫治技术.2组均减数4颗第一前磨牙,未使用任何增强支抗装置,分别记录其矫治时间,有效复诊次数及椅旁操作时间,并在治疗前(T0)和治疗后(T口1)拍摄X线头

  13. 发电机上机架千斤顶套筒拔出专用工具研制%Study and Manufacturing of Special Tool for Pulling Jack Sleeve of Upper Bracket of Generator

    Institute of Scientific and Technical Information of China (English)

    李军

    2016-01-01

    针对发电机组上机架支承(套筒式)安全销剪断更换,提出了一种新的方法。将原拆卸吊出更换方式,通过研制的专用工具革新为就地更换方式,简化了更换过程,节约了人力,提高了工作效率。重点介绍了新方法的使用原理、操作步骤,专用工具的研制过程和进一步的改进思路。%A new method for replacement of the safety pin sheared for the (sleeve type) bearing of the upper bracket of generator is pro-posed. Application of the newly studied and manufactured special tool , instead of dismantling and lifting for replacement, simplifies the re-placing process, reduces manpower and improves work efficiency. In the paper, application principle and operational step of the new method are focused as well as the studying&manufacturing process and further improving concept are described.

  14. 基于 CAE 支架的浇注系统与冷却系统的优化设计%CAE-based optimal design of feed system and cooling system in mould for bracket

    Institute of Scientific and Technical Information of China (English)

    谢金林; 盛希龙; 王小新

    2014-01-01

    CAE analysis was made to accurately predict the distribution of melting line of a coffee machine bracket formed in a mould with different feed system design in order to prevent the appearance of melting line on the high gloss surface of the product. Through CAE verification analysis on the mould cooling system, the heat collector zone was found out and optimized to meet the requirements for the product quality and production cycle.%以咖啡机支架为研究对象,通过CAE分析,准确预测了不同浇注系统的熔接痕分布情况,避免熔接痕在塑件的高亮外观面上产生,通过对模具冷却系统的CAE验证分析,发现了塑件的集热区域,并对冷却系统进行优化以满足塑件质量和生产周期的要求。

  15. A PCR-free cloning method for the targeted φ80 Int-mediated integration of any long DNA fragment, bracketed with meganuclease recognition sites, into the Escherichia coli chromosome.

    Science.gov (United States)

    Ublinskaya, Anna A; Samsonov, Valeriy V; Mashko, Sergey V; Stoynova, Nataliya V

    2012-06-01

    The genetic manipulation of cells is the most promising strategy for designing microorganisms with desired traits. The most widely used approaches for integrating specific DNA-fragments into the Escherichia coli genome are based on bacteriophage site-specific and Red/ET-mediated homologous recombination systems. Specifically, the recently developed Dual In/Out integration strategy enables the integration of DNA fragments directly into specific chromosomal loci (Minaeva et al., 2008). To develop this strategy further, we designed a method for the precise cloning of any long DNA fragments from the E. coli chromosome and their targeted insertion into the genome that does not require PCR. In this method, the region of interest is flanked by I-SceI rare-cutting restriction sites, and the I-SceI-bracketed region is cloned into the unique I-SceI site of an integrative plasmid vector that then enables its targeted insertion into the E. coli chromosome via bacteriophage φ80 Int-mediated specialized recombination. This approach allows any long specific DNA fragment from the E. coli genome to be cloned without a PCR amplification step and reproducibly inserted into any chosen chromosomal locus. The developed method could be particularly useful for the construction of marker-less and plasmid-less recombinant strains in the biotechnology industry.

  16. 磨除后酸蚀对氟斑牙正畸托槽脱落率的影响%Effects of bonding after microabrasion with normal acid etching time on losing ratio of orthodontic brackets to dental fluorosis

    Institute of Scientific and Technical Information of China (English)

    董晶; 张哲湛

    2016-01-01

    越高.对于中、重度氟斑牙的临床矫治,磨除后酸蚀法治疗效果优于延长酸蚀时间法.%Objective To investigate the effects of losing ratio of orthodontic brackets bonding after prolonged etching time (prolonged etching time method) and microabrasion with normal acid etching time (etching after microabrasion method) to different degree of dental fluorosis.Methods A total of 30 patients with dental fluorosis were selected from the cases treated in the Department of Stomatology,Lianyungang Hospital of Traditional Chinese Medicine.They were classified as 3 groups from mild to severe degree according to Dean's criteria,10 people per group.Patients within each group were randomly assigned to 2 subgroups,5 people per subgroup;prolonged etching time method and etching after microabrasion method were used,respectively,in each subgroup.The total and first losing ratios of brackets at five time points (1,2,4,12 and 24 weeks) were observed.The losing ratio differences of orthodontic brackets between the two disposing measures bonding to different degree of dental fluorosis were analyzed.Resuts The total bracket loss rates were 38.3% (46/120) and 21.4% (25/117),respectively,in severe dental fluorosis disposed by prolonged etching time method and etching after microabrasion method.It was significantly higher than that of the same processing method of mild and moderate dental fluorosis groups,in which the total bracket loss rates were 12.5% (15/120),18.1% (21/116),7.6% (9/118) and 5.8% (7/120),respectively,and the differences were statistically significant (x2 =21.12,11.87,8.96,12.24,all P < 0.01).The total loss rate of etching after microabrasion method was lower than that of prolonged etching time method in mild dental fluorosis group,the difference was not statistically significant (x2 =1.56,P > 0.05).The total loss rates of etching after microabrasion method were lower than that of prolonged etching time method in moderate and severe

  17. Avaliação do Índice de Remanescente Adesivo utilizando braquetes com e sem tratamento na base e a interação com três sistemas de colagem Evaluation of Adhesive Remnant Index using conventional mesh bases and sandblasted orthodontic bracket bases and three bonding systems

    Directory of Open Access Journals (Sweden)

    Lilian Maria Brisque Pignatta

    2009-02-01

    Full Text Available OBJETIVO: avaliar o Índice de Remanescente Adesivo (IRA em dentes bovinos após a descolagem de braquetes com e sem tratamento na base. METODOLOGIA: foram utilizados três sistemas de colagem ortodôntica para os dois padrões de base. Os dentes bovinos foram divididos em seis grupos de 40, de acordo com a base do braquete e o sistema de colagem. Vinte e quatro horas após a colagem foram realizados os testes de compressão em uma máquina de ensaios. A avaliação do IRA foi realizada em um estereomicroscópio por três examinadores calibrados. Foi utilizado o teste não paramétrico de Kruskal-Wallis, seguido do método de Dunn, para fazer as comparações múltiplas entre todos os grupos. RESULTADOS E CONCLUSÕES: observou-se que o tratamento das bases dos braquetes com óxido de alumínio não foi determinante para o aumento da adesividade entre o braquete e o adesivo. O grupo em que se utilizou braquetes com tratamento na base e adesivo TXT (3M-Unitek + Transbond Plus SEP (3M-Unitek apresentou a maior parte das fraturas na interface dente-adesivo (escore 4.AIM: To assess the Adhesive Remnant Index (ARI in bovine teeth after debonding mesh bases and sandblasted orthodontic bracket bases. METHODS: Were used three bonding systems for the two standards of base. The bovine teeth were divided into 6 groups of 40, according to the bracket base and to the bonding system. Twenty four hours after bonding they had been carried through shear bond strength tests in a universal testing machine. The assessment of ARI was performed in a stereomicroscopy by three calibrated examiners. It was used the non-parametric Kruskall-Wallis test, followed by Dunn's method, to do the multiple comparisons among all groups. RESULTS AND CONCLUSIONS: It was observed that the aluminum oxide sandblasting bracket bases was not determinative to the increase of the adhesiveness between bracket and adhesive. The group where it was used sandblasted orthodontic bracket bases and

  18. 后支点反吊三角托架挂篮技术研究%Study of Form Traveler with Rear Supports and Reversedly-Hung Triangular Brackets

    Institute of Scientific and Technical Information of China (English)

    胡若邻; 陈鸣

    2014-01-01

    The Second Penang Bridge is a three-span two-pylon cable-stayed bridge with a main span of 240 m and with double cable planes .The main girder belongs to the type of concrete edge beam and the bridge deck is 34 .6 m wide .To realize the asynchronous construction of the adjacent main girder sections ,avoid the condition that the prestress in the main girder will be shared by the bridge deck and weakened ,and overcome the problem of the need of reserving concrete post-cast-ing zone in the construction of using guyed form traveler with front supports ,a new type of form traveler with rear supports and reversedly-hung triangular brackets were developed .This type of form traveler has small self-weight and its reversedly-hung triangular brackets has rational load bearing performance ,therefore ,the stay force system transformation problem of the form traveler with front supports will be avoided .The overall stability and deformation resistance of the form traveler was advanced and optimized by optimizing the overall stability of the form traveler struc -ture and improving the load bearing capacity of hangers and the workmanship of the staggering of the construction joints .The form traveler was successfully used in the construction of the Second Penang Bridge in Malaysia .%马来西亚槟城二桥是一座主跨240 m 的三跨双塔双索面斜拉桥,采用混凝土边主梁形式,桥面宽34.6 m 。为实现相邻主梁节段异步施工,避免边主梁预应力被桥面板分摊削弱,同时克服前支点牵索挂篮施工中需预留后浇带混凝土的问题,开发了一种新型后支点反吊三角托架挂篮。该挂篮自重轻,反吊三角托架受力合理明确,可避免前支点挂篮斜拉索力系转换等问题。通过对该挂篮结构整体稳定性的优化、吊杆受力和施工接缝错台的工艺改进等措施,提升和优化了挂篮整体稳定性和抵抗变形能力,成功应用于马来西亚槟城二桥施工中。

  19. Effect of self-etching prime/adhesive on bond strength of ceramic orthodontic brackets%自酸蚀黏接剂对陶瓷托槽黏接强度的影响

    Institute of Scientific and Technical Information of China (English)

    崔占琴; 单丽华; 怀海丽

    2008-01-01

    背景:陶瓷托槽与牙齿间的黏接力较大,不容易安全去除,应用白酸蚀黏接剂能否降低其黏接强度,减少对牙釉质的损伤,一直是正畸医师关心的问题.目的:评估应用自酸蚀黏接系统黏接陶瓷托槽的黏接强度,并与国内临床最为常用的京津釉质黏接剂作比较.设计、时间及地点:对比观察实验,于2006-03在河北科技大学完成.材料:收集20个因正畸治疗拔除的完整前磨牙,要求所选牙齿表面釉质完好,有光泽、无裂纹、无龋坏、未曾接受任何化学治疗.陶瓷托槽采用美国3M公司的0.022系统标准方丝弓前磨牙陶瓷托槽,托槽底板面积12.61mm2;自酸蚀封闭剂和TransbondTM光固化黏接剂均为美国3M公司产品;传统酸蚀用京津釉质粘合剂由天津市合成材料研究所提供.方法:随机将20颗牙分为自酸蚀组和京津釉质组,每组10个牙齿,分别应用自酸蚀封闭剂+TransbondTM光固化黏接剂或京津釉质粘合剂黏接陶瓷托槽.主要观察指标:黏接托槽24 h后,应用抗剪切测试仪分别测定两组的抗剪切强度,并对每一牙面上的黏接剂残留量进行统计.结果:自酸蚀组平均抗剪切强度低于京津釉质组,但差异无显著性意义(P>0.05),均在临床可接受范围内.自酸蚀组黏接剂残留量低于京津釉质组,差异有显著性意义(P 0.05). The mean shear bond strength in the two groups was clinically acceptable. The residual adhesive remaining on the teeth was significantly less in the self-etching prime/adhesive group than in the Jingjin enamel adhesive group (P < 0.01).CONCLUSION: Self-etching prime/adhesive system used for bonding ceramic orthodontic brackets can satisfy clinical requirements. Moreover, its bond strength can be appropriately decreased and ceramic brackets are easily removed, thereby,injuries to enamel can be reduced.

  20. Application Analysis of No Bracket Invisible Orthodontic Technology in Orthodontics%无托槽隐形矫治技术在口腔正畸中的应用分析

    Institute of Scientific and Technical Information of China (English)

    沈强

    2015-01-01

    Objective To explore the application effect of invisible bracketless technique in orthodontics. Methods Selected 15 cases of adopt bracketless invisible orthodontic technique in treatment of dental exist clearance patients clinical date were retrospective analysis, compared patients’ mandible, changes in alveolar tissue and soft tissue changes before and after. Results Before and after receiving treatment in patients with upper and lower jaw, no changes of alveolar tissue, P>0.05, had no difference statistically significance, compared the soft tissue changes, P<0.05, had difference statistically significance. Conclusion Applications without brackets stealth technology in orthodontic treatment process can obtain a more ideal treatment effect.%目的:探讨无托槽隐形矫治技术在口腔正畸中的应用效果。方法选取采用无托槽隐形矫治技术治疗的15例牙齿间存在间隙患者的临床资料进行回顾性分析,比较矫治前后患者上下颌骨、牙槽组织变化情况及软组织变化情况。结果接受矫治前后患者上下颌骨、牙槽组织变化情况比较,P>0.05,差异不具有统计学意义,软组织变化情况对比,P<0.05,差异具有统计学意义。结论在口腔正畸过程中应用无托槽隐形矫治技术可获取更为理想的矫治效果。

  1. A repeated-measures analysis of the effects of soft tissues on wrist range of motion in the extant phylogenetic bracket of dinosaurs: Implications for the functional origins of an automatic wrist folding mechanism in Crocodilia.

    Science.gov (United States)

    Hutson, Joel David; Hutson, Kelda Nadine

    2014-07-01

    A recent study hypothesized that avian-like wrist folding in quadrupedal dinosaurs could have aided their distinctive style of locomotion with semi-pronated and therefore medially facing palms. However, soft tissues that automatically guide avian wrist folding rarely fossilize, and automatic wrist folding of unknown function in extant crocodilians has not been used to test this hypothesis. Therefore, an investigation of the relative contributions of soft tissues to wrist range of motion (ROM) in the extant phylogenetic bracket of dinosaurs, and the quadrupedal function of crocodilian wrist folding, could inform these questions. Here, we repeatedly measured wrist ROM in degrees through fully fleshed, skinned, minus muscles/tendons, minus ligaments, and skeletonized stages in the American alligator Alligator mississippiensis and the ostrich Struthio camelus. The effects of dissection treatment and observer were statistically significant for alligator wrist folding and ostrich wrist flexion, but not ostrich wrist folding. Final skeletonized wrist folding ROM was higher than (ostrich) or equivalent to (alligator) initial fully fleshed ROM, while final ROM was lower than initial ROM for ostrich wrist flexion. These findings suggest that, unlike the hinge/ball and socket-type elbow and shoulder joints in these archosaurs, ROM within gliding/planar diarthrotic joints is more restricted to the extent of articular surfaces. The alligator data indicate that the crocodilian wrist mechanism functions to automatically lock their semi-pronated palms into a rigid column, which supports the hypothesis that this palmar orientation necessitated soft tissue stiffening mechanisms in certain dinosaurs, although ROM-restricted articulations argue against the presence of an extensive automatic mechanism. Anat Rec, 297:1228-1249, 2014. © 2014 Wiley Periodicals, Inc.

  2. Invisible orthodontic correction without bracket for anterior tooth space caused by periodontal disease%无托槽隐形矫治牙周病致前牙间隙的临床研究

    Institute of Scientific and Technical Information of China (English)

    李尚峰

    2014-01-01

    Objective To explore the clinical efficacy of invisible orthodontic correction without bracket for anterior tooth space caused by periodontal disease.Methods 80 patients with anterior tooth space caused by periodontal disease were selected from our hospital from January,2012 to June,2013 and then were divided into a treatment group and a control group according to different treatments,40 cases for each group.The treatment group were treated with invisible orthodontic correction without bracket,while the control group with routine fixed orthodontic correction.The clinical efficacies,probing depths,plaque indexes,times for closing front tooth gap,and the changes of other parameters in the two groups were compared.Results After the treatment,the anterior tooth gap,tooth looseness,1-NA distance,and 1-NA angle were significantly improved in both groups,but the clinical indicators of the treatment group were significantly better than that of the control group (P < 0.05); the probing depth was significantly improved in both groups,but the lifting amplitude of the probing depth were significantly higher in the treatment group ([1.69 ± 0.26] mm) than in the control group ([1.56-± 0.18] mm) (P < 0.05) ; the plaque index (9.8%),time for closing front tooth gap ([2.0 ± 0.9] months),and appliance looseness (0) were significantly better in the treatment group than in the control group (P < 0.05).Conclusions Invisible orthodontic correction without bracket for anterior tooth space caused by periodontal disease doesn' t injury periodontal tissue in short term and is effective,suitable for the mild to moderate patients,and is worth being clinically generalized.%目的 探讨牙周病致前牙间隙进行无托槽隐形矫治的临床效果.方法 选择2012年1月至2013年6月我院收治的牙周病致前牙间隙患者80例,按治疗方法分为治疗组和对照组,各40例.治疗组采用无托槽隐形矫治疗法,对照组采用常规固定矫治疗法.比较两

  3. Compare of apical root resorption after orthodontic treatment with two sets of brackets%使用主动自锁托槽和被动自锁托槽正畸治疗后牙根吸收的比较

    Institute of Scientific and Technical Information of China (English)

    闫晓亮; 许国敏; 武斌; 孟秋菊; 郑学汜

    2016-01-01

    Objective: To compare the root resorption of incisors between active self-ligating brackets and passive self-ligation brackets in extraction patients. Methods: 30 extraction patients were divided into two groups: group 1(n=15, active self-ligating brackets) and group 2(n=15, passive self-ligation brackets). The cone bean computed tomography(CBCT) scans were obtained before/after orthodontic treatment to evaluate the magnitude of external apical root resortion(EARR). Resorption was evaluated as no, mild, moderate, severe, and extreme. Results: EARR was found for both groups. But, no differences in the degree of EARR were detected between the groups. Conclusions: No differences in the degree of EARR between active self-ligating brackets and passive self-ligation brackets.%目的:本研究旨在比较主动自锁托槽和被动自锁托槽用于拔牙病例治疗后的切牙牙根吸收情况,深入了解使用不同类型矫治器时牙根吸收有无差异,为正畸临床治疗提供参考。方法:筛选2012—2014年在龙华新区人民医院口腔科就诊的12—22岁矫治完成的患者30例,分为主动自锁托槽组(n=15)和被动自锁托槽组(n=15)。矫治技术均采用MBT直丝弓矫治技术,术前、术后拍摄锥束CT,观察上下切牙的牙根吸收情况,按照牙根吸收的严重程度分级为无吸收,轻度吸收,中度吸收,重度吸收,极重度吸收。全部数据以SPSS16.0软件进行统计学分析。结果:两组病例在治疗后均出现了牙根吸收,主动组与被动组相比较略有加重,但是差异无统计学意义(P>0.05)。结论:运用不同类型的自锁托槽进行正畸治疗均会造成牙根吸收,牙根吸收程度无明显差异。

  4. 亚历山大托槽与传统托槽矫治器矫治初期对牙周健康影响的比较研究%Comparison of perioldontal condition between conventional and Alexander brackets during the early alignment

    Institute of Scientific and Technical Information of China (English)

    王碧娟

    2015-01-01

    Objective To compare the periodontal indices and the proportion of Porphyromonas gingivalis(P.gingivalis)between conventional pre-adjusted brackets and Alexander brackets during the early alignment. Methods Forty patients(10 to 18 years old)were divided into 2 groups(group A:20 patients with Alexander brackets and group B:20 patients with conventional pre- adjusted brackets).Periodontal indices (GI,PLI,SBI and PD)and the proportion of P.gingivalis in the total bacteria in subgingival plagues were examined in both groups,using the polymerase chain reaction (PCR) method. Results No significant difference was found in the indices recorded and the proportion of P.gingivalis between Groups A and B after 3 months of treatment. Conclusion Alexander brackets P.gingivalis did not have an advantage over conventional bracket with respect to the periodontal status during the early alignment.%目的:对比亚历山大托槽与传统托槽矫治器排齐阶段牙周指数及龈下菌斑中牙龈卟啉单胞菌(P. gingivalis)的发展变化。方法:选取10~18周岁接受正畸治疗的患者40例,按矫治器类型分两组。实验组20例,采用ORMCO公司生产的ALEXANDER托槽;对照组20例,采用杭州新亚生产的直丝托槽。由同一医生分别检测40例患者在矫治器戴入前,戴入后3个月检查牙周临床指标(包括牙龈指数、菌斑指数、龈沟出血指数、探诊深度),同时采集龈下菌斑样本,利用荧光实时定量聚合酶链反应检测样本P.gingivalis和总细菌的数量,计算P.gingivalis在总细菌的构成比。分析牙周临床指标和P.gingivalis的构成比在矫治前后的变化情况。结果:治疗3个月后两组间牙周指数(GI、PLI、SBI、PD)及P.gingivalis在总细菌的构成比差异无显著性。结论:ALEXANDER托槽不会更有利于牙周组织的健康,牙周的健康状况取决于口腔卫生状况。

  5. On distributive laws in derived bracket construction

    CERN Document Server

    Uchino, K

    2011-01-01

    In this short note we will introduce a new type of binary quadratic algebra, which is called a Lie-Leibniz algebra (also-called Lie-Loday algebra), and prove that the operad of Lie-Leibniz algebras is Koszul. The Koszul dual operad is studied.

  6. To explore the clinical value of Smart Clip self-ligating bracket in patients with Angle ClassⅠ malocclusion by the non-ex- traction orthodontic treatment%Smart Clip自锁托槽在非拔牙矫治安氏Ⅰ类错牙合中的临床价值分析鄢

    Institute of Scientific and Technical Information of China (English)

    韩红娟; 吴浩; 任小华; 黄飞; 牟雁东

    2016-01-01

    Objective:To explore the clinical value of smart Clip self-ligating bracket in patients with mild/moderate crowding angle classⅠmalocclusion by the non-extraction orthodontic treatment. Method: Selected 86 cases with mild /moderate crowding angle classⅠmalocclusion in my hospital oral section for orthodontic treatment during march 2012 to January 2014, according to different treatment, were divided into self-ligating group (used smart Clip self-ligating bracket, 40 cases) and traditional group (used MBT straight-wire bracket, 46 cases), and compared the correct effect between two groups. Result: First premolares space, first molares space, UI-NA space and UI-SN angle increased in two groups after treatment,and the change value before and after treatment in self-ligating group were obviously greater than those in tradi-tional group (P<0.05);total correction time and chair operation time in self-ligating group were obviously shortened, com-pared traditional group(P<0.05);the score of Zung's depression-anxiety assessment in self-ligating group were obviously de-clined, compared traditional group (P<0.05). Conclusion:The correct effect of smart Clip self-ligating bracket is superior to traditional MBT straight-wire bracket in patients with mild/moderate crowding angle classⅠmalocclusion, helps to improve the dentist efficiency, and it is worth spreading.%目的:探讨Smart Clip自锁托槽对轻中度拥挤安氏Ⅰ类错牙合畸形患者进行非拔牙矫治的临床应用价值。方法:选择2012年3月~2014年1月收治的轻中度拥挤安氏Ⅰ类错牙合患者86例,根据所采用矫治技术的不同,分为自锁组(采用Smart Clip自锁托槽矫治器治疗,共40例)和非自锁组(采用MBT直丝弓托槽矫治器治疗,共46例),并对两组间的治疗效果作对比分析。结果:两组患者经矫治后的第一前磨牙间距、第一磨牙间距、UI-NA距以及UI-SN角均较治疗前增大,自锁组患者治疗前

  7. Estudo comparativo de diferentes prescrições de braquetes pré-ajustados em modelos virtuais pelo Método de Elementos Finitos Comparative study of different pre-adjusted brackets prescriptions on virtual models, by Finite Elements Method

    Directory of Open Access Journals (Sweden)

    Murilo Fernando Neuppmann Feres

    2009-08-01

    comprised of an upper left central and lateral incisors, and a upper left cuspid. These elements were subjected to force vectors which simulated tip and torque pre-adjustments of Alexander, Andrews, Capelozza, MBT, Ricketts, and Roth brackets. After the referred simulation, data concerning the spatial displacement of the incisal and apical points were registered in order to determine the position newly assumed by the teeth long axis, as well as its constituent points. RESULTS: Most of the prescriptions reacted similarly to the simulation, regarding to the evaluated parameters. However, significant differences were found. Ricketts' lateral incisor presented the smallest buccal inclination of its long axis. Moreover, Ricketts' upper left cuspid presented the greatest mesial and buccal inclination of its long axis. A qualitative analysis performed with the upper central incisor indicated that there was a larger distal movement of the apical points for the prescriptions whose authors advocated the greatest tip values (Andrews, Capelozza, Roth and Alexander. Furthermore, it was observed pronounced crown buccal displacements for the prescriptions whose authors indicated greatest torque values (Ricketts, MBT, Alexander and Roth.

  8. Avaliação da resistência ao cisalhamento de braquetes colados com resinas ortodônticas fluoretadas Evaluation of shear bond strength of brackets bonded with orthodontic fluoride-releasing composite resins

    Directory of Open Access Journals (Sweden)

    Marcia Cristina Rastelli

    2010-06-01

    Full Text Available OBJETIVO: avaliar a resistência ao cisalhamento de braquetes metálicos colados com resinas que contêm flúor, comparando-as a uma resina convencional; e analisar a quantidade de adesivo remanescente na superfície do esmalte. MÉTODOS: sessenta pré-molares foram divididos aleatoriamente em 3 grupos: Grupo I - Concise (3M, Grupo II - Ultrabond (Aditek do Brasil e Grupo III - Rely-a-Bond (Reliance. Após a colagem dos braquetes, as amostras foram termocicladas (500 ciclos nas temperaturas de 5°C e 55°C. Após 48 horas, foram submetidas aos ensaios mecânicos de cisalhamento na direção oclusocervical, com velocidade de carga de 0,5mm/min, em uma máquina MTS 810. RESULTADOS: foram observadas resistências médias ao cisalhamento de 24,54±6,98MPa para o Grupo I, de 11,53±6,20MPa para o Grupo II e de 16,46±5,72MPa para o Grupo III. A Análise de Variância determinou diferença estatística entre as médias de resistência ao cisalhamento entre os grupos (p OBJECTIVE: To evaluate the shear bond strength of stainless steel brackets bonded with fluoride releasing composite resins, comparing them with a conventional resin and to analyze the amount of resin left on the enamel surface. METHODS: Sixty premolars were randomly divided into three groups: Group I - Concise (3M, Group II - Ultrabond (Aditek do Brasil and Group III - Rely-a-Bond (Reliance. After bonding, the samples were thermocycled (500 cycles at 5ºC and 55ºC temperatures. After 48 hours they were subjected to shear bond strength testing, in the occluso-gingival direction, using an MTS 810 Universal Testing Machine with load speed of 0.5 mm/min. RESULTS: The results demonstrated a mean shear bond strength of 24.54 ± 6.98 MPa for Group I, 11.53 ± 6.20 MPa for Group II, and 16.46 ± 5.72 MPa for Group III. Analysis of Variance (ANOVA determined a statistical difference in the mean shear bond strengths between groups (p < 0.001. The Tukey test evidenced that the averages of the

  9. Prediction of crack growth of surface crack at bracket toe of ship under random wave loading condition%肘板趾端表面裂纹在随机波浪载荷作用下的疲劳扩展预报

    Institute of Scientific and Technical Information of China (English)

    武锐锋; 黄小平

    2012-01-01

    The bracket toe is one of the fatigue hot spots in ship and ocean structures. In this paper, the SIFs of surface cracks at bracket toe are analyzed by 3D FEA and compared with the results of SIF magnification factors of the same size surface crack at T joints calculated by equations recommended in BS7910. Results show that the SIF magnification factor of surface crack at bracket toe at deepest point is close to that of T-butt joints, while the results at surface point are quite different when the crack length is larger than the bracket thickness. The fatigue crack growth of a surface crack at bracket toe in bottom plate of a Ro-Ro passenger ship was predicted by generating series stress amplitude with zero mean stress which the long-term stress range distribution obey Weibull distribution, the stress intensity factors were calculated by FEA results and the T-joint formula in BS7910 respectively, the unique crack growth rate curve model is employed. The welded residual stress effect is considered in the equivalent stress intensity factor amplitude. It shows thai the predicted fatigue lives of the SIF of surface crack at bracket toe calculated by FEA and by the T-joint formula are very close. The formula for calculating the SIF of surface crack at weld toe of T joint are recommended to the SIF calculation of the surface crack at bracket toe. The unique crack growth rate curve model is recommended in prediction of the fatigue crack propagation life of weld toe of ship hull under random wave loads.%肘板趾端是船舶与海洋结构的疲劳热点.文章用三维有限元分析了趾端表面裂纹应力强度因子修正系数的变化规律,并与BS7910推荐的典型节点表面裂纹应力强度因子公式计算结果作了对比,结果表明趾端表面裂纹应力强度因子沿深度方向的放大系数和T型节点相差很小,而表面端点应力强度因子修正系数则当裂纹长度在肘板厚度范围内时和T型节点相差很小,超出后