Friction, binding and notching are the factors that contribute to resistance to sliding during orthodontic tooth movement. However, most attempts at reducing resistance aim only to reduce the archwire/ligature friction. In this study, a novel bracket with a unique design aimed to reduce all three components of resistance to sliding. Four types of brackets (passive and active self-ligating, traditionally ligated and the novel bracket, (n=5, each) were tested at 0, 2, 4, 6, and 8ᵒ of tip on a 0.019 x 0.025”archwire. The resistance to sliding values were recorded. At 0ᵒ, the passive self-ligating and novel bracket showed reduced resistance when compared to the traditionally ligated bracket (P< 0.05). At the other angles of tip, no differences were observed among the brackets. These data suggest that the novel bracket could potentially decrease the resistance to sliding during orthodontic treatment and further studies are indicated to test the improved bracket design.

Magister Scientiae Dentium - MSc(Dent) / Background: A close marginal adaptation between the tooth and the bracket base is important since it provides the space for the adhesive. In order to withstand and resist the orthodontic forces exerted as well as everyday forces like mastication and oral hygiene practices, the adhesive material to the bracket must have sufficient sheer bond strength. This means that no deformations, cracks, or fractures should occur within the bracket material and adhesive (Keizer et al., 1976). Aim: The aim of this study was to determine the accuracy of the marginal adaptation of the bracket bases of seven different brands of orthodontic brackets to the tooth surface of a right upper first premolar (ie. Abzil, Forestadent, GAC, Gemini, IMD, Ormco and Victory LP). Method: This research was an in vitro, descriptive comparison study. Fifteen caries and crack free intact human first premolars were used. The teeth were obtained from patients requiring extractions for orthodontic purposes and collected from Tygerberg Oral Health Centre. A convenience sample method was used, where whenever an upper caries free premolar was extracted, the parent was asked if the tooth could be used for this study and consent was obtained. The crowns of the 15 teeth were cleaned and polished with pumice and rubber cups for 10 seconds (as the clinician would do prior to bracket cementation). The same 15 teeth were used with the seven different brands of brackets in order to establish a comparison of the adaptability of the brackets. The brackets were placed at a set orthodontic prescription of 4mm (measured from the slot area of the bracket to the tip of the buccal cusp of the tooth) on the upper first premolars. After bracket placement, the dontrix gauge was applied to the bracket to engage the slot area. The brackets were held in place with a constant force of 0.70 Newton (N) by the dontrix gauge. This allowed for reproducibility for the seven brackets with all fifteen teeth. In order to assess the space between the brackets and the teeth no adhesive was used. The space between the margins of the bracket and tooth interface was viewed under the Stereomicroscope (Carl Zeiss microscope, Zeiss Stemi508) at 50 times magnification. A two way mixed measures ANOVA was run to determine whether there were differences between the seven brackets placed at six points on the tooth surface. Results: GAC had the smallest overall mean measurement between bracket base and tooth surface followed by Ormco and Gemini respectively. Abzil had the largest overall mean measurement for the six points around the bracket

No description available.

Made available in DSpace on 2014-06-11T19:27:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-08-05Bitstream added on 2014-06-13T18:30:59Z : No. of bitstreams: 1 guimaraes_acm_me_guara.pdf: 1463910 bytes, checksum: 86d009497e85e3bccfe639908d568618 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Braquetes ortodônticos são feitos de diversos tipos de materiais, tais como, metais, cerâmicas e polímeros. Entre todos os materiais metálicos, o aço inoxidável é o mais empregado devido ao seu baixo custo associado a sua resistência à corrosão. No ambiente oral, eles estão sujeitos a fluídos agressivos e variações de pH, levando a liberação de íons nos tecidos e fluídos. Modificações na superfície destas ligas foram realizados utilizando tratamentos mecânicos, eletroquímicos, químicos e físicos. O carbono amorfo hidrogenado (a-C: H) preparado para técnicas de deposição apresentam muitas propriedades atraentes como alta dureza, serem químicamente inertes e biocompatíveis. Neste estudo in vitro, filmes de a-C:H foram depositados em braquetes ortodônticos pela técnica de deposição química por plasma de radiofreqüência (PECVD) e inibiu a liberação de íons níquel. Após o tratamento de superfície, os braquetes foram colados em incisivos bovinos com uma resina composta e as amostras foram imersas em soro fisiológico por 30 dias à 37 º C. Durante o tempo de imersão as amostras foram lavadas e imersas em flúor diariamente. Antes da imersão, o arranjo estrutural dos filmes foi analisado por espectroscopia de Raman e medidas do ângulo de contato foram realizadas, a fim de avaliar a molhabilidade da superfície. Espectrometria de absorção atômica foi usada para medir a liberação de elementos a partir de amostras e a análise superficial foi realizada em microscópio eletrônico de varredura (MEV). Os resultados mostraram que o revestimento previne a liberação de Ni dos braquetes nos testes estatísticos e o níquel foi liberado de outros grupos sem tratamento de superfície . A análise de variância não indicou diferença significativa entre os grupos depois do ensaio de cisalhamento. / Orthodontics brackets have been made from a variety of materials such as metals, ceramics and polymers. Among all the metallic materials, stainless steel are the most popular due low cost associated with reasonable corrosion resistance. In oral environment, they are subject aggressive fluids and pH variation can be leave nickel ions release to body tissues and fluids. Surface modifications of these alloys have been realized using mechanical, electrochemical, chemical and physical treatments. Hydrogenated amorphous carbon (a-C:H) prepared by deposition techniques have very attractive properties such as high hardness, chemical inertness and biocompatibility. In this in vitro study, a-C:H films were deposited on orthodontics brackets by r.f. plasmaenhanced chemical vapour deposition (PECVD) from inhibited nickel ions release. After treatment, brackets were bonded to bovine incisors with a composite resin and samples were immersed in physiological serum for 30 days at 37 ºC. During immersion time samples were brushed and/or immersed in mouthwashes daily. Prior immersion, the structural arrangement of films was probed by Raman spectroscopy and contact angle measurements were carried out in order to evaluate the wettability of surface. Atomic absorption spectrophotometry was used to measure the release of elements from the samples and SEM for surface analysis. Results showed that the coating prevents Ni release of brackets for statistic test and nickel was released for others groups. Analysis of variance no indicated significance different among groups after shear testing.

Resumo: Braquetes ortodônticos são feitos de diversos tipos de materiais, tais como, metais, cerâmicas e polímeros. Entre todos os materiais metálicos, o aço inoxidável é o mais empregado devido ao seu baixo custo associado a sua resistência à corrosão. No ambiente oral, eles estão sujeitos a fluídos agressivos e variações de pH, levando a liberação de íons nos tecidos e fluídos. Modificações na superfície destas ligas foram realizados utilizando tratamentos mecânicos, eletroquímicos, químicos e físicos. O carbono amorfo hidrogenado (a-C: H) preparado para técnicas de deposição apresentam muitas propriedades atraentes como alta dureza, serem químicamente inertes e biocompatíveis. Neste estudo in vitro, filmes de a-C:H foram depositados em braquetes ortodônticos pela técnica de deposição química por plasma de radiofreqüência (PECVD) e inibiu a liberação de íons níquel. Após o tratamento de superfície, os braquetes foram colados em incisivos bovinos com uma resina composta e as amostras foram imersas em soro fisiológico por 30 dias à 37 º C. Durante o tempo de imersão as amostras foram lavadas e imersas em flúor diariamente. Antes da imersão, o arranjo estrutural dos filmes foi analisado por espectroscopia de Raman e medidas do ângulo de contato foram realizadas, a fim de avaliar a molhabilidade da superfície. Espectrometria de absorção atômica foi usada para medir a liberação de elementos a partir de amostras e a análise superficial foi realizada em microscópio eletrônico de varredura (MEV). Os resultados mostraram que o revestimento previne a liberação de Ni dos braquetes nos testes estatísticos e o níquel foi liberado de outros grupos sem tratamento de superfície . A análise de variância não indicou diferença significativa entre os grupos depois do ensaio de cisalhamento. / Abstract: Orthodontics brackets have been made from a variety of materials such as metals, ceramics and polymers. Among all the metallic materials, stainless steel are the most popular due low cost associated with reasonable corrosion resistance. In oral environment, they are subject aggressive fluids and pH variation can be leave nickel ions release to body tissues and fluids. Surface modifications of these alloys have been realized using mechanical, electrochemical, chemical and physical treatments. Hydrogenated amorphous carbon (a-C:H) prepared by deposition techniques have very attractive properties such as high hardness, chemical inertness and biocompatibility. In this in vitro study, a-C:H films were deposited on orthodontics brackets by r.f. plasmaenhanced chemical vapour deposition (PECVD) from inhibited nickel ions release. After treatment, brackets were bonded to bovine incisors with a composite resin and samples were immersed in physiological serum for 30 days at 37 ºC. During immersion time samples were brushed and/or immersed in mouthwashes daily. Prior immersion, the structural arrangement of films was probed by Raman spectroscopy and contact angle measurements were carried out in order to evaluate the wettability of surface. Atomic absorption spectrophotometry was used to measure the release of elements from the samples and SEM for surface analysis. Results showed that the coating prevents Ni release of brackets for statistic test and nickel was released for others groups. Analysis of variance no indicated significance different among groups after shear testing. / Orientadora: Ana Paula Rosifini Alves Claro / Coorientador: Maria Cristina Rosifini Alves Resende / Banca: Sandra Giacomi Scheneider / Banca: Maria da Glória Chiarello Mattos / Mestre

Submitted by Angela Maria de Oliveira (amolivei@uepg.br) on 2018-03-01T13:44:47Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Andrés Fernando Montenegro.pdf: 11976346 bytes, checksum: fa909dec838336e8c5a4ed73180bb65b (MD5) / Made available in DSpace on 2018-03-01T13:44:47Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Andrés Fernando Montenegro.pdf: 11976346 bytes, checksum: fa909dec838336e8c5a4ed73180bb65b (MD5) Previous issue date: 2017-10-16 / O objetivo deste estudo foi verificar o efeito da densidade de energia e o tempo de exposição de fotopolimerizadores LED de terceira geração em uma resina ortodôntica disponível comercialmente nos valores de microdureza, cisalhamento, índice de remanescente de resina e grau de conversão. Para tanto, foram realizados 3 experimentos: Experimento 1, o objetivo foi avaliar o grau de conversão (DC) e microdureza vickers (MHV) da resina ortodôntica utilizando dois LEDs de terceira geração, assim como, protocolos de fotoativação diferentes. Foram necessários 80 brackets cerâmicos e 80 brackets metálicos, sendo divididos em 16 grupos experimentais (n=10) tendo os seguintes grupos para cada LED: um grupo controle, diminuição da metade do tempo de exposição do grupo controle, um quarto do tempo do grupo controle, função turbo ou plasma para os LEDs Bluephase e Valo, respetivamente. Imediatamente após a polimerização, foram realizados os ensaios de DC e MHV. O experimento 2, objetivou verificar a influência de diferentes densidades de energia emitidas por dois fotoativadores LED de alta potência nas propriedades físicas e mecânicas de uma resina ortodôntica em brackets metálicos. Foram necessários 80 pré-molares superiores, sendo usadas as superfícies vestibulares dos dentes para a colagem dos 80 brackets metálicos. Os dentes foram divididos aleatoriamente em 8 grupos experimentais (n=10), sendo: um grupo controle, redução da metade do tempo de exposição do grupo controle, um quarto do tempo do grupo controle, função plasma ou turbo para cada LED estudado, sendo Valo e Bluephase. Após 24 horas da polimerização, foram realizados os testes de cisalhamento (SBS), índice remanescente de resina (ARI) e MHV. O objetivo do experimento 3 foi verificar a influência de diferentes densidades de energia depositadas por dois fotoativadores LED diferentes de alta potência nas propriedades físicas e mecânicas de uma resina ortodôntica em brackets cerâmicos. Foram necessários 80 dentes pré-molares superiores hígidos, sendo utilizadas as superfícies linguais ou palatinas dos dentes para colagem dos 80 brackets cerâmicos. Os dentes foram divididos aleatoriamente em 8 grupos experimentais (n=10), foram formados grupos iguais para cada LED Valo e Bluephase: um grupo controle, diminuição da metade do tempo de exposição do grupo controle, um quarto do tempo do grupo controle, função turbo do LED Bluephase ou plasma do LED Valo. Após 24 horas da polimerização, foram realizados os testes de SBS, ARI e MHV. Os resultados de cada experimento foram analisados através de testes estatísticos específicos, para determinar se houve ou não diferença estatisticamente significativa. Para o experimento 1 foram realizados ANOVA de duas vias e teste de Tukey (α=0,05), para o experimento 2 e 3 foram realizados Anova de duas vias com testes de Tukey (α=0,05). O experimento 1 mostrou que os grupos dos brackets cerâmicos tem baixa variação, porém pequenas mudanças no aumento dos valores da energia aplicada em Joules totais aumentam os valores de DC e MHV, nos brackets metálicos pelo fato de impedir a passagem da luz o DC e HVK diminuem significativamente, permanecendo dentro dos parâmetros considerados normais. O experimento 2 mostrou que ambos LED utilizados foram efetivos tanto na função standard como na turbo ou plasma, sendo que as funções turbo ou plasma ofereceram resultados similares aos do controle, efetivando mesmo com a redução do tempo para a polimerização dos brackets metálicos. No experimento 3 não houve diferença estatisticamente significativa nos grupos analisados. Os LEDs estudados proporcionaram valores suficientes de Joules em alguns grupos experimentais sendo este suficiente para atingir bons valores no DC, SBS e MHV. O uso de LEDs com uma potência adequada, sendo o mínimo de 1200 mW/cm2, ou o uso de uma potência elevada de entre 2400 a 3200 mW/cm2 e um curto período de tempo de exposição entre 3 a 6 segundos, são efetivos para a colagem de acessórios ortodônticos. / The objective of this study was to verify the effect of energy density and the time of exposure of third generation LED light curing agents on a commercially available orthodontic resin in the values of microhardness, shear, resin remaining index and degree of conversion. Three experiments were carried out: Experiment 1, the objective was to evaluate the degree of conversion (DC) and microhardness vickers (MHV) of the orthodontic resin using two third generation LEDs, as well as different photoactivation protocols. 80 ceramic brackets and 80 metallic brackets were required and divided into 16 experimental groups (n=10), with the following groups for each LED: control group, one half, one quarter of the control group time, turbo or plasma function for the Bluephase and Valo LEDs, respectively. Immediately after the polymerization, the DC and MHV assays of the specimens were performed. The experiment 2, aimed to verify the influence of different energy densities emitted by two high power LED photoactivators on the physical and mechanical properties of an orthodontic resin in metallic brackets. For this experiment, 80 carious cavity-free, superior human premolar teeth were used, and the buccal surfaces of the teeth were used for the bonding of the 80 metal brackets. The teeth were randomly divided into 8 experimental groups (n=10), with the following groups being a control group, half the time of exposure of the control group, one quarter of the time in the control group, plasma or turbo function for each LED studied, being Valo and Bluephase. After polymerization, the teeth and specimens were stored 24h at 37°C to perform the shear tests (SBS), resin remaining index (ARI) and MHV. The objective of experiment 3 was to verify the influence of different energy densities deposited by two different LED light-curing on the physical and mechanical properties of an orthodontic resin in ceramic brackets. For this experiment, it was necessary to have 80 carious free upper premolar human teeth, using the lingual or palatine surfaces of the teeth for bonding the 80 ceramic brackets. The teeth were randomly divided into 8 experimental groups (n=10), equal groups were formed for each Valo and Bluephase LEDs: one control group, one half-time control group exposure time, one-fourth time control group, function LED Bluephase turbo or LED Valo Plasma. After polymerization, the teeth and specimens were stored 24 hours at 37°C to perform the SBS, ARI and MHV tests. The results of each experiment were analyzed by specific statistical tests to determine whether or not there was a statistically significant difference. For experiment 1, 2 and two-way ANOVA and Tukey's test (α=0.05) were performed. Experiment 1 showed that the groups of ceramic brackets have low variation, but small changes in the increase of the values of the applied energy in total Joules increase the values of DC and MHV in the metallic brackets because it prevents the passage of light the DC and HVK decrease significantly, remaining within the parameters considered normal. Experiment 2 showed that both LEDs were effective both in the standard function and in the turbo or plasma, and the turbo or plasma functions gave similar results to the control, even effecting with the reduction of the time for the polymerization of the metal brackets. In the experiment 3 there was no statistically significant difference in the analyzed groups. The studied LEDs provided sufficient values of Joules in some experimental groups being sufficient to reach good values in DC, SBS and HVK. The use of LEDs with adequate power, being at least 1000 mW/cm2, or the use of a high power of between 2400 and 3200 mW/cm2 and a short period of exposure of between 3 to 6 seconds, are sufficient for the bonding of orthodontic accessories.