RESUMO Objetivo: Avaliar a cor de diferentes resinas ortodônticas expostas a três enxaguantes bucais, por um intervalo de tempo prolongado (simulação de 10 anos de envelhecimento). Métodos: 160 espécimes foram distribuídos em quatro grupos, de acordo com a resina de colagem ortodôntica (Concise, Transbond XT, Transbond Plus Color Change e Natural Ortho). Cada grupo foi exposto a diferentes tipos de enxaguantes bucais: à base de álcool (Listerine®), isento de álcool (Oral-B®), clorexidina (Periogard®) ou água destilada, como controle. Os espécimes foram submetidos a dois ciclos de manchamento e envelhecimento artificial. A cor foi avaliada por meio de um espectrofotômetro digital no início do experimento e após cada ciclo. O sistema utilizado para avaliar as alterações de cor foi o CIE L*a*b*. Os dados foram analisados utilizando-se o teste ANOVA e o teste post-hoc de Tukey. Resultados: Após a simulação de 10 anos de envelhecimento, as resinas Transbond XT e Natural Ortho não apresentaram diferenças estatisticamente significativas no ∆E, quando expostas a diferentes enxaguantes bucais. Os espécimes do grupo Concise expostos ao enxaguante bucal sem álcool apresentaram diferença significativa quando comparados aos espécimes do mesmo grupo expostos aos outros enxaguantes bucais. Os espécimes do grupo Transbond Plus Color Change expostos à clorexidina e ao enxaguante bucal à base de álcool apresentaram diferença significativa quando comparados aos espécimes dos grupos expostos à água e ao enxaguante bucal sem álcool. Conclusão: Todas as resinas ortodônticas avaliadas apresentaram alterações de cor clinicamente perceptíveis quando expostas a pelo menos um dos enxaguantes bucais, com exceção da resina ortodôntica Natural Ortho. A resina Concise exposta à solução isenta de álcool foi a que apresentou os maiores valores de alteração de cor.

ABSTRACT Objective: To assess the color of different orthodontic resin bonding agents exposed to three antiseptic mouthrinses for a prolonged time interval (10-year aging simulation). Methods: 160 specimens were distributed into four groups, according to the orthodontic resin bond agent (Concise, Transbond XT, Transbond Plus Color Change, and Natural Ortho). Each group was exposed to different antiseptic mouthrinses: alcohol-based (Listerine®), alcohol-free (Oral-B®), chlorhexidine (Periogard®) and distilled water as the control. Specimens were submitted to two cycles of staining and artificial aging. Color was evaluated by means of a digital spectrophotometer at the beginning of the experiment and after every cycle. The system used to assess color changes was the CIE L*a*b*. Data was analyzed using the ANOVA and Tukey post-hoc test. Results: After simulation of 10 years of aging, Transbond XT and Natural Ortho composites presented no statistically significant differences in ∆E when exposed to different mouthrinses. The Concise composite specimens exposed to alcohol-free mouthrinse presented a significant difference when compared with specimens from the same group exposed to other antiseptic mouthrinses. Transbond Plus Color Change specimens exposed to chlorhexidine mouthrinse and to alcohol-containing mouthrinse presented a significant difference when compared with the specimens from the group exposed to water and alcohol-free antiseptic. Conclusion: All orthodontic resin bonding agents tested presented clinically perceptible color changes when exposed to at least one of the mouthrinses, except for the Natural Ortho composite. The Concise composite exposed to the alcohol-free solution was the resin that presented the highest color change values.

RESUMO Objetivo: Realizar simulação pelo método de elementos finitos (MEF) para determinar a tensão e o deslocamento dos mini-implantes e do aparelho expansor durante a expansão rápida da maxila, variando a quantidade e localização dos mini-implantes. Métodos: Para realização da simulação computacional, foi utilizada uma malha tridimensional para a maxila, mini-implantes e aparelho expansor. As comparações foram feitas em seis configurações de MARPE (Mini-implant Assisted Rapid Palatal Expander), com quantidades e localização diferentes dos mini-implantes. Foram modeladas uma sutura fechada, que recebeu duas ativações de 0,25 mm, e outra sutura com abertura de 0,5 mm, que recebeu 20 ativações, também de 0,25 mm. Resultados: Para a sutura fechada, os valores máximos de deslocamento nos mini-implantes foram entre 0,253 e 0,280 mm, e as tensões, entre 1348,9 e 2948,2 MPa; e no aparelho expansor, os valores de deslocamento foram entre 0,256 e 0,281 mm, e as tensões, entre 738,52 e 1207,6 MPa. Para a sutura aberta, os valores máximos de deslocamento nos mini-implantes foram entre 2,57 e 2,79 mm, e as tensões, entre 5.765,3 e 10.366 MPa; e no aparelho os deslocamentos máximos foram entre 2,53 e 2,89 mm, e as tensões, entre 4.859,7 e 9.157,4 MPa. Conclusões: Ocorreram maiores concentrações de tensão no mini-implante do que no braço do aparelho expansor. Nas simulações com configuração de três mini-implantes, foi observada sobrecarga de tensão no mini-implante isolado. Os deslocamentos dos mini-implantes e braços do aparelho foram semelhantes em todas as simulações.

ABSTRACT Objective: In this study, simulations were performed by the finite element method (FEM) to determine the tension and displacement in mini-implants and in expander appliance during rapid maxillary expansion, by varying the number and location of the mini-implants. Methods: For the computational simulation, a three-dimensional mesh was used for the maxilla, mini-implants and expander appliance. Comparisons were made on six different Mini-implant Assisted Rapid Palatal Expander (MARPE) configurations, by varying the amount and location of mini-implants. A closed suture was design and received two activations of 0.25 mm, and an open suture had a 0.5-mm aperture that received 20 activations, also of 0.25 mm. Results: For the closed suture, the maximum displacement values in the mini-implants were between 0.253 and 0.280 mm, and stress was between 1,348.9 and 2,948.2 MPa; in the expander appliance, the displacement values were between 0.256 and 0.281 mm, and stress was between 738.52 and 1,207.6 MPa. For the open suture, the maximum displacement values in the mini-implants were between 2.57 and 2.79 mm, and stress was between 5,765.3 and 10,366 MPa; in the appliance, the maximum displacements was between 2.53 and 2.89 mm, and stress was between 4,859.7 and 9,157.4 MPa. Conclusions: There were higher stress concentrations in the mini-implant than in the expander arm. In the simulations with a configuration of three mini-implants, stress overload was observed in the isolated mini-implant. Displacements of the mini-implants and arms of the appliance were similar in all simulations.

RESUMO Objetivo: avaliar o volume e a morfologia da porção média da faringe (PMF) em adolescentes com diferentes padrões esqueléticos no sentido anteroposterior. Método: para esse estudo transversal, foram selecionados cento e vinte e seis pacientes (56 homens e 70 mulheres) que tinham tomografia computadorizada de feixe cônico (TCFC) em seus registros. Os participantes foram classificados de acordo com o valor do ângulo ANB, em Classe I (1o ≥ ANB ≤ 3o), Classe II (ANB > 3o) e Classe III (ANB < 1o). O volume total (Vt), a área axial mínima (AxMin) e a morfologia da PMF e de suas subdivisões - velofaringe (VF) e orofaringe (OF) - foram avaliados na TCFC e em software de reconstrução tridimensional (3D) de imagens. As comparações intergrupos foram realizadas por meio dos testes ANOVA e post-hoc de Tukey. As correlações entre os valores de Vt e Axmin das vias aéreas com os valores do ângulo ANB foram testadas por meio de análise de regressão linear, considerando-se o sexo como uma covariável. Resultados: diferença estatisticamente significativa entre os grupos foi observada apenas no Vt da VF; indivíduos Classe II apresentaram Vt significativamente menor (6.863,75 ± 2.627,20 mm3) do que indivíduos Classe III (9.011,62 ± 3.442,56 mm3) (p< 0,05). Não foram observadas diferenças significativas entre os grupos em nenhuma outra variável avaliada, nem na PMF, nem na OF (p> 0,05). Foi evidenciada uma correlação negativa significativa entre Vt e Axmin e os valores do ângulo ANB; dimorfismo sexual foi observado para algumas variáveis. Conclusões: indivíduos Classe II apresentam o menor Vt da VF. O Vt e a Axmin tenderam a diminuir quando os valores do ângulo ANB aumentaram, em todas as regiões avaliadas.

ABSTRACT Objective: To assess the volume and morphology of the middle region of the pharynx (MRP) in adolescents with different anteroposterior craniofacial skeletal patterns. Methods: One hundred twenty-six patients (56 male and 70 female), who had cone-beam computed tomography (CBCT) within their records, were selected for this cross-sectional study. Participants were classified, according to their ANB angle value, in Class I (1o ≤ ANB ≤ 3o), Class II (ANB > 3o) and Class III (ANB < 1o). The total volume (tV), minimum axial area (AxMin) and morphology of the MRP and its subdivisions - velopharynx (VP) and oropharynx (OP) - were characterized by CBCT and 3-dimensional image reconstruction software. Intergroup comparisons were performed by ANOVA and Tukey post-hoc tests. Correlations between tV and Axmin with the ANB angle values were tested using linear regression analysis, considering sex as covariable. Results: Statistically significant difference between groups were observed in tV only for the VP region; Class II individuals presented significantly lower tV (6863.75 ± 2627.20 mm3) than Class III subjects (9011.62 ± 3442.56 mm3) (p< 0.05). No significant differences were observed between groups for any other variable assessed, neither in MRP nor in the OP region (p> 0.05). A significant negative correlation was evidenced between tV and Axmin and the ANB angle values; sexual dimorphism was observed for some variables. Conclusions: Class II subjects have smaller tV in the VP region. tV and Axmin tend to decrease in all evaluated regions when the ANB angle values increase.

ABSTRACT Introduction: In dental practice, low-level laser therapy (LLLT) and high-intensity laser therapy (HILT) are mainly used for dental surgery and biostimulation therapy. Within the Orthodontic specialty, while LLLT has been widely used to treat pain associated with orthodontic movement, accelerate bone regeneration after rapid maxillary expansion, and enhance orthodontic tooth movement, HILT, in turn, has been seen as an alternative for addressing soft tissue complications associated to orthodontic treatment. Objective: The aim of this study is to discuss HILT applications in orthodontic treatment. Methods: This study describes the use of HILT in surgical treatments such as gingivectomy, ulotomy, ulectomy, fiberotomy, labial and lingual frenectomies, as well as hard tissue and other dental restorative materials applications. Conclusion: Despite the many applications for lasers in Orthodontics, they are still underused by Brazilian practitioners. However, it is quite likely that this demand will increase over the next years - following the trend in the USA, where laser therapies are more widely used.

Objetivo: testar a hipótese nula de que o processo de envelhecimento em braquetes autoligáveis não é superior ao de braquetes convencionais. Métodos: Vinte e cinco braquetes metálicos convencionais (GN, 3M/Unitek; GE, GAC; VE, Aditek) e 25 autoligáveis (SCs, 3M/Unitek; INs, GAC; ECs, Aditek) de três fabricantes (n = 150) foram submetidos ao envelhecimento em solução de NaCl à temperatura constante de 37 ± 1ºC, durante 21 dias. O conteúdo de íons níquel, cromo e ferro na solução coletada com 7, 14 e 21 dias foi quantificado por meio de espectrofotometria de absorção atômica. Depois de completado o processo de envelhecimento, os braquetes foram analisados com microscópio eletrônico de varredura (MEV), em magnificações de 22x e de 1.000x. Resultados: comparando-se a liberação de metais por braquetes autoligáveis e convencionais do mesmo fabricante, observou-se que o grupo SCs liberou mais níquel (p < 0,05) que o grupo GN após 7 e 14 dias, mas menos cromo (p < 0,05) após 14 dias e menos ferro (p < 0,05) nos três períodos experimentais. O grupo INs liberou menos ferro (p < 0,05) que o grupo GE após 7 dias, e menos níquel, cromo e ferro (p < 0,05) após 14 e 21 dias. O grupo ECs liberou mais níquel, cromo e ferro (p < 0,05) que o grupo VE após 14 dias; entretanto, liberou menos níquel e cromo (p < 0,05) após 7 dias e menos cromo e ferro (p < 0,05) após 21 dias. A análise no MEV demonstrou alterações na topografia da superfície de braquetes convencionais e autoligáveis. Conclusões: o processo de envelhecimento em braquetes autoligáveis não foi superior ao de braquetes convencionais do mesmo fabricante. A hipótese nula está aceita.

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.

INTRODUÇÃO: diferentes protocolos de irradiação por laser de baixa potência (LBP) têm sido testados para potencializar o movimento ortodôntico; entretanto, há resultados divergentes. Foi sugerido que seu efeito bioestimulador ocorre nas fases de proliferação e diferenciação celular, não agindo em estágios tardios. OBJETIVO: avaliar o efeito de dois protocolos de irradiação do LBP na movimentação ortodôntica: um com irradiações diárias e outro em que irradiações foram realizadas apenas nos períodos iniciais. MÉTODOS: trinta e seis ratos Wistar foram divididos em grupos controles (GC1, GC2 e GC3) e irradiados (GIr1, GIr2 e GIr3), de acordo com a presença de dispositivo ortodôntico, a presença de irradiação, o tipo de protocolo de irradiação e a data de eutanásia (3º ou 8º dia de experimento). Ao final dos períodos experimentais, foram realizadas mensurações da movimentação dentária, análise qualitativa das reações celulares e teciduais do periodonto e contagem de vasos sanguíneos no ligamento periodontal. RESULTADOS: a quantidade de movimentação não diferiu entre os grupos num mesmo tempo experimental (p < 0,05). A análise qualitativa revelou maior atividade absortiva nos grupos irradiados ao final de 7 dias, especialmente quando as irradiações foram diárias. Nos grupos irradiados diariamente, a contagem de vasos foi aumentada em relação aos animais isentos de dispositivo ortodôntico e de aplicações de LBP (p < 0,05). CONCLUSÃO: apesar de verificada angiogênese em certos grupos irradiados, os protocolos de irradiação testados não foram capazes de acelerar a movimentação dentária, e foi possível verificarem-se absorções radiculares.

INTRODUCTION: Different low-level laser (LLL) irradiation protocols have been tested to accelerate orthodontic tooth movement (OTM). Nevertheless, divergent results have been obtained. It was suggested that the stimulatory action of low level laser irradiation occurs during the proliferation and differentiation stages of bone cellular precursors, but not during later stages. OBJECTIVE: The purpose of this study was to determine the effect of two protocols of LLL irradiation on experimental tooth movement: One with daily irradiations and another with irradiations during the early stages. METHODS: Thirty-six rats were divided into control groups (CG1, CG2, CG3) and irradiated groups (IrG1, IrG2, IrG3) according to the presence of: experimental tooth movement, laser irradiation, type of laser irradiation protocol and date of euthanasia (3th or 8th day of experiment). At the end of experimental periods, a quantitative evaluation of the amount of OTM was made and the reactions of the periodontium were analyzed by describing cellular and tissue reactions and by counting blood vessels. RESULTS: The amount of OTM revealed no significant differences between groups in the same experimental period (p < 0.05). Qualitative analysis revealed the strongest resorption activity in irradiated groups after seven days, especially when using the daily irradiation protocol. There was a higher number of blood vessels in irradiated animals than in animals without orthodontic devices and without laser irradiation (p < 0.05). CONCLUSION: Moreover, angiogenesis was verified in some of the irradiated groups. The irradiation protocols tested were not able to accelerate OTM and root resorption was observed while they were applied.

The aim of this study was to test the hypothesis that there is a direct relationship between surface structure and tensile strength of orthodontic alloys submitted to different levels of welding current. Three types of alloys were assessed. One hundred and eight cross-sectional test specimens ("X") were made, 18 for each wire combination, and divided into 6 groups: SS (steel-steel); SN (steel-NiTi); SB (steel-Beta-Ti); NN (NiTi-NiTi); NB (NiTi-Beta-Ti) and BB (Beta-Ti-Beta-Ti), submitted to 6 spot-welding procedures at different levels of current (Super Micro Ponto 3000). Student-Newman-Keuls, Wilcoxon signed-rank, and Kruskal-Wallis tests were used (p < .05). Statistical difference was found between SN group and all the other alloy combinations (p < .05). Initial roughness of alloys ranged from .04 to .55 Ra, with statistical difference between groups (p < .001). The hypothesis was rejected and the tensile strength of Ti-alloys combinations Steel × Beta-Ti was significantly affected by the current level at P50, which changed the properties and structure of the wires.

OBJECTIVE: To assess and compare the number of Streptococcus mutans and Candida albicans colonies in patients with Haas and Hyrax appliances before and after insertion. METHODS: The sample consisted of 84 patients requiring orthodontic treatment. For all patients a midpalatal suture expansion was indicated. Patients were randomly divided into Group HA, who used the Haas appliance (n = 42) and Group HY, who used the Hyrax appliance (n = 42). Initially and thirty days after appliance insertion all patients were submitted to saliva collections. The saliva was diluted followed by seeding in Mitis Salivarius and CHROMagar media, for growth of S. mutans and C. albicans respectively. RESULTS: Results showed statistically significant difference between groups HA and HY for Streptococcus mutans and Candida albicans (p <0.05). Haas appliance promoted greater S. mutans and C. albicans proliferation when compared to Hyrax appliance. CONCLUSION: The Haas appliance favored greater proliferation of S. mutans and C. albicans when compared with the Hyrax appliance. Insertion of the appliances resulted in greater buildup of microorganisms.

INTRODUCTION: Extraction decisions are extremely important in during treatment planning. In addition to the extraction decision orthodontists have to choose what tooth should be extracted for the best solution of the problem and the esthetic/functional benefit of the patient. OBJECTIVE: This article aims at reviewing the literature relating the advantages, disadvantages and clinical implications of asymmetric extractions to orthodontics. METHODS: Keywords were selected in English and Portuguese and the EndNote 9 program was used for data base search in PubMed, Web of Science (WSc) and LILACS. The selected articles were case reports, original articles and prospective or retrospective case-control studies concerning asymmetrical extractions of permanent teeth for the treatment of malocclusions. CONCLUSION: According to the literature reviewed asymmetric extractions can make some specific treatment mechanics easier. Cases finished with first permanent molars in Class II or III relationship in one or both sides seem not to cause esthetic or functional problems. However, diagnosis knowledge and mechanics control are essential for treatment success.

The aim of this study was to measure the thickness of the hard palate and its overlying mucosa using cone-beam computed tomography (CBCT), for purposes of miniscrew placement. The sample comprised 36 CBCT scans of patients aged 12 to 52 years from a database of the Orthodontics Department of the Federal University of Rio de Janeiro. Paracoronal views of the palatal region were reconstructed at 4, 8, 16 and 24 mm posterior to the incisive foramen. In each reconstruction measurements were taken at the suture, 3 mm and 6 mm bilaterally to it. Wilcoxon's test verified the differences between the selected regions. Total bone height decreased from the anterior to the posterior region. In cross sections 4, 16 and 24, bone height decreased from the suture laterally to the 3 mm region and then increased in the 6 mm region. The cortical thickness does not seem to be a concern because it presented a mean thickness of at least 1 mm at all sites evaluated. The measurements of the mucosa thickness decreased from lateral to median and from anterior to posterior regions. The most suitable areas for miniscrew placement in the palate are located 4 mm posterior to the incisive foramen, in the median or paramedian regions 3 mm adjacent to the suture.

Primary stability is absence of mobility in the bone bed after mini-implant placement and depends on bone quality among other factors. Bone quality is a subjective term frequently considered as bone density. The aim of this preliminary study was to evaluate bone density in two bovine pelvic regions and verify the primary stability of miniscrews inserted into them. Forty bone blocks were extracted from bovine pelvic bones, 20 from iliac and 20 from pubic bone, all of them containing cortical bone about 1 mm thick. Half of the sections extracted from each bone were designated for histological evaluation of bone density (trabecular bone area - TBA) and the other half for bone mineral density (BMD) evaluation by means of central dual-energy X-ray absorptiometry (DEXA). Then, twenty self-drilling miniscrews (INPÒ, São Paulo, Brazil) 1.4 mm in diameter and 6 mm long were inserted into the bone blocks used for BMD evaluation. Peak implant insertion torque (IT) and pull-out strength (PS) were used for primary stability evaluation. It was found that iliac and pubic bones present different bone densities, iliac bone being less dense considering BMD and TBA values (P > 0.05). However, the miniscrew primary stability was not different when varying the bone type (P < 0.05). IT and PS were not influenced by these differences in bone density when cortical thickness was about 1 mm thick.

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 and III. However, a significant difference was found in group IV. CONCLUSION: The shear bond strength seems not to be affected by activation and storage of the self-etching primer for a 5 day period. More studies are necessary to evaluate other characteristics of the material after its activation and storage for long periods of time.

OBJETIVO: o objetivo dos autores desse estudo foi comparar o método de análise de dentição mista que utiliza tomografia computadorizada de feixe cônico para avaliar os diâmetros dos dentes intraósseos com os métodos de Moyers, Tanaka-Johnston e radiografias oblíquas em 45º. MÉTODOS: foram realizadas medidas, na arcada inferior, dos diâmetros mesiodistais dos incisivos permanentes irrompidos, nos modelos de gesso com auxílio de paquímetro digital e estimativa do tamanho de pré-molares e caninos permanentes ainda não irrompidos utilizando-se a tabela de Moyers e a fórmula de predição de Tanaka-Johnston. Nas radiografias oblíquas em 45º, caninos e pré-molares foram medidos utilizando-se o mesmo instrumento. Nas tomografias, as mesmas unidades dentárias foram aferidas por meio de ferramentas do programa Dolphin. RESULTADOS: a análise estatística revelou elevada concordância entre o método tomográfico e o radiográfico, e baixa concordância entre o tomográfico e os demais avaliados. CONCLUSÃO: a tomografia computadorizada de feixe cônico mostrou-se confiável para análise da dentição mista e apresenta algumas vantagens em relação aos métodos comparados: a observação e mensuração dos dentes intraósseos individualmente, com a possibilidade, contudo, de visualizá-los sob diferentes perspectivas e sem superposição de estruturas anatômicas.

OBJECTIVE: The aim of this study was to evaluate the method for mixed-dentition analysis using Cone-Beam Computed Tomography for assessing the diameter of intra-osseous teeth and compare the results with those obtained by Moyers, Tanaka-Johnston, and 45-degree oblique radiographs. METHODS: Measurements of mesial-distal diameters of erupted lower permanent incisors were made on plaster cast models by using a digital calliper, whereas assessment of the size of non-erupted permanent pre-molars and canines was performed by using Moyer's table and Tanaka-Johnston's prediction formula. For 45-degree oblique radiographs, both canines and pre-molars were measured by using the same instrument. For tomographs, the same dental units were gauged by means of Dolphin software resources. RESULTS: Statistic analysis revealed high agreement between tomographic and radiographic methods, and low agreement between tomographs and other methods being evaluated. CONCLUSION: Cone-Beam Computed Tomography was accurate for mixed-dentition analysis in addition to presenting some advantages over compared measurement methods: observation and measurement of intra-osseous teeth individually with the possibility, however, to view them from different prospects and without superimposition of anatomical structures.

OBJETIVO: analisar pelo método dos elementos finitos o deslocamento dos molares superiores frente a três diferentes inclinações do arco externo do aparelho extrabucal na tração do tipo cervical. MÉTODOS: maxila, dentes montados em má oclusão de Classe II e aparelho foram modelados através de formulação variacional e seus valores reproduzidos em coordenadas X, Y e Z. Foram realizadas simulações em microcomputador tipo PC, utilizando o programa ANSYS versão 8.1. Cada modelo de arco externo reproduziu linhas de força que passaram (1) acima (AcCR), (2) abaixo (AbCR) e (3) no centro de resistência (CR) do molar permanente superior de um mesmo modelo portador de má oclusão de Classe II. A avaliação restringiu-se ao movimento inicial dos molares frente à força extrabucal de 4 Newtons. RESULTADOS: o movimento distal inicial dos molares, tendo como ponto de referência a mesial do tubo, foi maior na coroa do modelo AbCR (0,47x10-6), e maior na raiz do modelo AcCR (0,32x10-6), provocando inclinações da coroa para distal e mesial, respectivamente. No modelo CR, os pontos na coroa (0,15x10-6) e raiz (0,12x10-6) deslocaram-se para distal equilibradamente, resultando em movimento de translação. Em todos os modelos, numa vista oclusal, houve tendência de rotação distal inicial da coroa, porém no modelo CR esse movimento foi muito pequeno. No sentido vertical (Z), todos os modelos revelaram movimento extrusivo (AbCR= 0,18x10-6; CR= 0,62x10-6; AcCR= 0,72x10-6). CONCLUSÃO: a simulação computacional do uso de aparelho extrabucal com tração cervical revelou a ocorrência de movimento extrusivo e distal, podendo ser por inclinação distal de coroa, de raiz ou movimento de translação.

OBJECTIVE: To analyze maxillary molar displacement by applying three different angulations to the outer bow of cervical-pull headgear, using the finite element method (FEM). METHODS: Maxilla, teeth set up in Class II malocclusion and equipment were modeled through variational formulation and their values represented in X, Y, Z coordinates. Simulations were performed using a PC computer and ANSYS software version 8.1. Each outer bow model reproduced force lines that ran above (ACR) (1), below (BCR) (2) and through the center of resistance (CR) (3) of the maxillary permanent molars of each Class II model. Evaluation was limited to the initial movement of molars submitted to an extraoral force of 4 Newtons. RESULTS: The initial distal movement of the molars, using as reference the mesial surface of the tube, was higher in the crown of the BCR model (0.47x10-6) as well as in the root of the ACR (0.32x10-6) model, causing the crown to tip distally and mesially, respectively. On the CR model, the points on the crown (0.15 x10-6) and root (0.12 x10-6) moved distally in a balanced manner, which resulted in bodily movement. In occlusal view, the crowns on all models showed a tendency towards initial distal rotation, but on the CR model this movement was very small. In the vertical direction (Z), all models displayed extrusive movement (BCR 0.18 x10-6; CR 0.62 x10-6; ACR 0.72x10-6). CONCLUSIONS: Computer simulations of cervical-pull headgear use disclosed the presence of extrusive and distal movement, distal crown and root tipping, or bodily movement.

As new orthodontic resin adhesives continue to be marketed, rapid and sensitive tests for examining their toxic effects at the ' cell and tissue level ' are needed because patient safety has been identifi ed as a legal concept. The objective of the present study was to evaluate the cytotoxicity and degree of monomer conversion of orthodontic adhesives over different time periods. Seven adhesives: Transbond® XT, Transbond® Color Change, Quick Cure, EagleBond, Orthobond®, Fill Mágic® and Biofix® were evaluated for their cytotoxicity in L929 fibroblastic cells and for their degree of monomer conversion over different time periods. Three control groups were also analysed: Positive control (C+), consisting of Tween 80 cell detergent; Negative control (C-), consisting of PBS; and cell control (CC), consisting of cells exposed to any material. The dye-uptake technique that involves the absorption of a neutral red dye in viable cells was used for the cytotoxicity evaluation and the degree of conversion was evaluated using spectroscopy with infrared. The results showed the cytotoxicity of the adhesives at 24, 48, 72 and 168 hours. At these times, the viability values presented for these materials were statistically different from the groups CC and C- (p < 0.05). At 168 hours, all the groups showed low cytotoxicity with high cell viability and with no statistical difference with the groups CC and C- (P > 0.05). In the monomer conversions there was a percentage increase of monomer conversion from 24 to 72 hours. A direct correlation could be observed between cytotoxicity and monomer conversions. From this work it can be concluded that all adhesives evaluated are cytotoxic at the times of 24, 48 and 72 hours. Monomers continued conversion even after photopolymerization had stopped.