Mechanical Properties of Mini-Implants Used in Extra-Radicular Anchorage

ABSTRACT Objective: To evaluate the mechanical properties of mini-implants (MIs) manufactured from stainless steel and compare them with conventional titanium-aluminum-vanadium alloy MIs. Material and Methods: The following groups were formed: G1 (n=24), 8×1.5 mm steel MIs; G2 (n=24), 12×2.0 mm steel MIs; and G3 (n=24), 10×1.5 mm titanium MIs. The 72 MIs were inserted in the infra zygomatic crest region of the maxilla and retromolar trigone in the jaw of 10 pigs. Pull-out, insertion torque, fracture and percussion tests were performed in order to measure the tensile strength, primary stability and fracture strength of MIs. A digital torque gauge was used to measure insertion and fracture torque, a universal mechanical testing machine was used for pull-out testing and a periotest device was used to measure the micromovement of MIs. For morphological and MI component evaluation, scanning electron microscopy (SEM) was performed. D'Agostino & Pearson, Kruskal-Wallis, and Dunn post-hoc and normality tests were used. Results: G2 insertion and fracture torques were significantly higher than G1 and G3 insertion and fracture torques (p<0.05). The pull-out and percussion tests presented similar values among the groups. SEM revealed that the fracture point was predominantly on the fourth thread for steel MIs (G1 and G2) and on the seventh thread for titanium-aluminum-vanadium MIs (G3). Conclusion: The mechanical properties of stainless steel MIs are superior to those of titanium-aluminum-vanadium alloy MIs.

Mechanical properties of anatomic finishing files: xp-endo finisher and xp-clean

Abstract The aim of the present study was to evaluate the cyclic fatigue of two anatomic finishing files: XP-Endo Finisher and XP-Clean. Roughness pattern and the micro-hardness of the files were also assessed. Instruments were subjected to cyclic fatigue resistance measuring the time to fracture in an artificial stainless-steel canal with a 60° angle and a 5-mm radius of curvature. The fracture surface of all fragments was examined with a scanning electron microscope. The roughness of the working parts was quantified by using a profilometer and the micro-hardness test was carried out using a Vickers hardness tester. Results were statistically analyzed using a student´s t-test at a significance level of P < 0.05. Weibull analysis was also performed. XP-Endo Finisher presented significantly longer cyclic fatigue life than XP-Clean instruments (P<0.05). XP-Endo Finisher was able to withstand 1000% more cycles to fracture when compared to XP-Clean instruments. SEM visual inspection of the fracture surfaces revealed fractographic characteristics of ductile fracture in all tested instruments; wide-ranging forms of dimples were identified and no plastic deformation in the helical shaft of the fractured instruments was observed. When mean life was compared XP-Endo Finisher lasted longer than XP-Clean with a probability of 99.9%. XP-Endo Finisher instruments also exhibited significantly lower roughness than XP-Clean instruments (P<0.05). No differences in the micro-hardness was observed between the files (P>0.05). It can be concluded that XP-Endo Finisher instruments showed improved performance when compared with XP-Clean instruments, demonstrating higher cyclic fatigue resistance and lower roughness.

Resumo O objetivo do presente estudo foi avaliar a fadiga cíclica de dois instrumentos finalizadores anatômicos: XP-Endo Finisher e XP-Clean. O padrão de rugosidade e a micro dureza dos instrumentos também foram avaliados. Os instrumentos foram submetidos à resistência à fadiga cíclica, medindo o tempo de fratura em um canal artificial de aço inoxidável com um ângulo de 60 ° e um raio de curvatura de 5 mm. A superfície de fratura de todos os fragmentos foi examinada com um microscópio eletrônico de varredura. A rugosidade dos instrumentos foi quantificada usando um perfilômetro e o teste de micro dureza foi realizado usando um testador de dureza Vickers. Os resultados foram analisados ​​estatisticamente usando o teste t de student em um nível de significância de p<0,05. A análise Weibull também foi realizada. XP-Endo Finisher apresentou vida de fadiga cíclica significativamente mais longa do que os instrumentos XP-Clean (p<0,05). XP-Endo Finisher foi capaz de suportar 1000% mais ciclos para fratura quando comparado aos instrumentos XP-Clean. A inspeção visual em microscópio eletrônico de varredura das superfícies de fratura revelou características fractográficas da fratura dúctil em todos os instrumentos testados. Não foi observada deformação plástica no eixo helicoidal dos instrumentos fraturados. Quando o tempo para a fratura foi comparado entre os instrumentos, o XP-Endo Finisher durou mais do que o XP-Clean com uma probabilidade de 99,9%. Os instrumentos XP-Endo Finisher também exibiram uma rugosidade significativamente menor do que os instrumentos XP-Clean (p<0,05). Não foram observadas diferenças na micro dureza entre os arquivos (p>0,05). Pode-se concluir que os instrumentos XP-Endo Finisher apresentaram desempenho melhorado em comparação com os instrumentos XP-Clean, demonstrando maior resistência à fadiga cíclica e menor rugosidade.

Influence of biomaterials on scintigraphic diagnosis of periprosthetic infections. Ceftizoxime-99m technetium model

Abstract Purpose: To compare the influence of two metallic implants in the diagnosis of periprosthetic infection using 99m technetium-labeled ceftizoxime. Methods: Twenty rats were randomly divided into four groups, which received sterile and contaminated titanium and stainless steel implants. After 3 weeks, scintilographic images were obtained using a gamma chamber. Radioactivity counts were obtained for the region of interest (ROI) on the operated and non-operated paws. Results: Groups A, B, and C showed homogenous distribution of the radiopharmaceutical. Hyper uptake was observed in the operated paw from group D. The ROI target count was higher in the two groups with stainless steel implants. Among the control groups, the count was higher in the stainless steel group. Furthermore, among the contaminated groups, the uptake was higher in the stainless steel group, with a significant difference. The target: non-target ratio was significantly lower in the control and contaminated groups with both titanium and stainless steel, but the comparison between control groups and contaminated groups was only significant in the former. The cpm/g observed after a decay of 48h showed statistically significant differences between groups. Conclusion: Different biomaterials used in implants have an influence on the results of scintigraphy with 99mTc-CFT.

Growth, viability and architecture of biofilms of Listeria monocytogenes formed on abiotic surfaces

Abstract The pathogenic bacterium Listeria monocytogenes can persist in food processing plants for many years, even when appropriate hygienic measures are in place, with potential for contaminating ready-to-eat products and, its ability to form biofilms on abiotic surfaces certainly contributes for the environmental persistence. In this research, L. monocytogenes was grown in biofilms up 8 days attached to stainless steel and glass surfaces, contributing for advancing the knowledge on architecture of mature biofilms, since many literature studies carried out on this topic considered only early stages of cell adhesion. In this study, biofilm populations of two strains of L. monocytogenes (serotypes 1/2a and 4b) on stainless steel coupons and glass were examined using regular fluorescence microscopy, confocal laser scanning microscopy and classic culture method. The biofilms formed were not very dense and microscopic observations revealed uneven biofilm structures, with presence of exopolymeric matrix surrounding single cells, small aggregates and microcolonies, in a honeycomb-like arrangement. Moreover, planktonic population of L. monocytogenes (present in broth media covering the abiotic surface) remained stable throughout the incubation time, which indicates an efficient dispersal mechanism, since the culture medium was replaced daily. In conclusion, even if these strains of L. monocytogenes were not able to form thick multilayer biofilms, it was noticeable their high persistence on abiotic surfaces, reinforcing the need to focus on measures to avoid biofilm formation, instead of trying to eradicate mature biofilms.

Effect of nanotechnology in self-etch bonding systems on the shear bond strength of stainless steel orthodontic brackets

ABSTRACT Objective: To evaluate the effect of silica dioxide (SiO2) nanofillers in different bonding systems on shear bond strength (SBS) and mode of failure of orthodontic brackets at two experimental times. Methods: Ninety-six intact premolars were divided into four groups: A) Conventional acid-etch and primer Transbond XT; B) Transbond Plus self-etch primer; and two self-etch bonding systems reinforced with silica dioxide nanofiller at different concentrations: C) Futurabond DC at 1%; D) Optibond All-in-One at 7%. Each group was allocated into two subgroups (n = 12) according to experimental time (12 and 24 hours). SBS test was performed using a universal testing machine. ARI scores were determined under a stereomicroscope. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to determine the size and distribution of nanofillers. One-way ANOVA was used to compare SBS followed by the post-hoc Tukey test. The chi-square test was used to evaluate ARI scores. Results: Mean SBS of Futurabond DC and Optibond All-in-One were significantly lower than conventional system, and there were no significant differences between means SBS obtained with all self-etch bonding systems used in the study. Lower ARI scores were found for Futurabond DC and Optibond All-in-One. There was no significant difference of SBS and ARI obtained at either time points for all bonding systems. Relative homogeneous distribution of the fillers was observed with the bonding systems. Conclusion: Two nanofilled systems revealed the lowest bond strengths, but still clinically acceptable and less adhesive was left on enamel. It is advisable not to load the brackets immediately to the maximum.

RESUMO Objetivo: avaliar o efeito das nanopartículas de dióxido de silício (SiO2), presentes em diferentes sistemas adesivos, na resistência ao cisalhamento da colagem (RAC) e no modo de fratura de braquetes ortodônticos avaliados em dois momentos. Métodos: noventa e seis pré-molares intactos foram divididos em quatro grupos: A) condicionador ácido convencional e primer Transbond XT; B) primer autocondicionador Transbond Plus; e dois sistemas adesivos autocondicionantes reforçados com nanopartículas de dióxido de silício em diferentes concentrações, C) DC Futurabond a 1%; D) Optibond All-In-One a 7%. Cada grupo foi dividido em dois subgrupos (n = 12), de acordo com o tempo para realização do teste (12 e 24 horas). O teste da RAC foi realizado em uma máquina universal de ensaios. Os resultados do índice de adesivo remanescente foram determinados com um estereomicroscópio. Para determinar o tamanho e a distribuição das nanopartículas, utilizou-se microscopia eletrônica de varredura (MEV) e microscopia eletrônica de transmissão (MET). O ANOVA a um critério foi usado para comparar a RAC, seguido pelo teste post-hoc de Tukey. O teste qui-quadrado foi usado para avaliar os índices de adesivo remanescente. Resultados: a RAC média do Futurabond DC e do Optibond All-In-One foi menor do que a do sistema convencional, de forma estatisticamente significativa; e não houve diferença estatisticamente significativa entre os níveis médios de RAC obtidos nos sistemas adesivos autocondicionantes avaliados nesse estudo. Os menores índices de adesivo remanescente foram observados com o Futurabond DC e o Optibond All-In-One. Não houve, entre os sistemas adesivos, diferença significativa na RAC e nos índices de adesivo remanescente obtidos nos dois tempos de aplicação. Foi observada uma distribuição relativamente homogênea das partículas nos sistemas adesivos. Conclusão: os dois sistemas com nanopartículas demonstraram menor RAC, mas ainda aceitável e com o menor índice de adesivo remanescente no esmalte. É, assim, aconselhável não submeter os braquetes à carga máxima logo após a colagem.

Evaluation of deflection forces of orthodontic wires with different ligation types

Abstract The aim of this study was to evaluate deflection forces of orthodontic wires of different alloys engaged into conventional brackets using several ligation types. Stainless steel, conventional superelastic nickel-titanium and thermally activated nickel-titanium archwires tied into conventional brackets by a ring-shaped elastomeric ligature (RSEL), a 8-shaped elastomeric ligature (8SEL) and a metal ligature (ML) were tested. A clinical simulation device was created especially for this study and forces were measured with an Instron Universal Testing Machine. For the testing procedure, the block representing the maxillary right central incisor was moved 0.5 and 1 mm bucco-lingually at a constant speed of 2 mm/min, and the forces released by the wires were recorded, in accordance with the ISO 15841 guidelines. In general, the RSEL showed lighter forces, while 8SEL and ML showed higher values. At the 0.5 mm deflection, the 8SEL presented the greatest force, but at the 1.0 mm deflection the ML had a statistically similar force. Based on our evaluations, to obtain lighter forces, the thermally activated nickel-titanium wire with the RSEL are recommended, while the steel wire with the 8SEL or the ML are recommended when larger forces are desired. The ML exhibited the highest force increase with increased deflections, compared with the elastomeric ligatures.

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

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.

OBJETIVO: o objetivo deste estudo foi avaliar se a abertura e o fechamento repetitivo do clipe de braquetes autoligáveis podem causar deformação plástica do clipe.MÉTODOS: três tipos de braquetes autoligáveis ativos/interativos estéticos (n = 20) foram testados: In-Ovation C, Quicklear e WOW. Um dispositivo realizou, de forma controlada e padronizada, 500 ciclos de abertura e de fechamento do clipe, com instrumentos e técnicas adequadas, tal como recomendado pelo fabricante de cada tipo de braquete. Dois ensaios de tração, um antes e um depois dos ciclos repetitivos, foram realizados para se avaliar a rigidez dos clipes. Para o ensaio de tração, um fio de 0,40 x 0,40mm de aço inoxidável foi inserido no slot do braquete e adaptado em uma máquina universal de ensaios (EMIC DL2000), sendo as medições registradas. Na porção retilínea da curva de carregamento dos clipes, a inclinação é definida por uma equação de primeiro grau, determinando o coeficiente de elasticidade (rigidez) do clipe.RESULTADOS: os resultados quanto à deformação plástica não mostraram nenhuma diferença significativa entre os tipos de braquetes, antes e depois dos 500 ciclos de abertura e de fechamento (p = 0,811). Foram encontradas diferenças significativas na rigidez entre os três tipos de braquetes (p = 0,005): o braquete WOW demonstrou valores médios mais elevados, e o braquete Quicklear demonstrou valores mais baixos, independentemente do ciclo de abertura e fechamento.CONCLUSÃO: movimentos repetitivos controlados de abertura e de fechamento do clipe não alteraram a rigidez ou causaram deformação plástica.

Study of novel coating strategy for coronary stents: simutaneous coating of VEGF and anti- CD34 antibody / Estudo da nova estratégia de revestimento para stents coronários: revestimento simultâneo de VEGF e anticorpo anti-CD34

Abstract Introduction: Intravascular coronary stenting has been used in the treatment of coronary artery disease (CAD), with a major limitation of in-stent restenosis (ISR). The 316 stainless steel has been widely used for coronary stents. In this study, we developed a novel coating method to reduce ISR by simultaneously coating vascular endothelial growth factor (VEGF) and anti-CD34 antibody on 316L stainless steel. Methods: Round 316L stainless steel sheets in the D-H group were polymerized with compounds generated from condensation reaction of dopamine and heparin using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS). Sixteen sheets from the D-H group were further immersed into 1ug/ml VEGF165 and 3mg/ml heparin sodium one after another for 10 times, and named as the D-(H-V)10 group. Eight sheets from the D-(H-V)10 group were coated with anti-CD34 antibody and termed as the D-(H-V)10-A group. Immunofluorescence assay and ELISA were used to evaluate whether the 316L stainless steel disks were successfully coated with VEGF and anti-CD34 antibody. Results: The results of immunofluorescence assay and ELISA showed that VEGF could be detected in the D-(H-V)10 and D-(H-V)10-A group, suggesting the steel sheets were successfully covered with VEGF. Anti-CD34 antibody could only be observed in the D-(H-V)10-A group, which was the only group coated with CD34 antibody. Both results suggested that the 316L stainless steel sheets were successfully coated with VEGF and anti-CD34 antibody. Conclusion: Our study developed a method to simultaneously coat VEGF and anti-CD34 antibody to stainless metal steel. This research serves as a fundamental role for a novel coating strategy. .

Resumo Introdução: O stent coronário intravascular tem sido utilizado no tratamento de doença arterial coronária, com uma maior limitação de restenose intra-stent (RIS). O aço inoxidável 316 tem sido amplamente utilizado para stents. Neste estudo, foi desenvolvido um novo método de revestimento para reduzir a RIS para revestir simultaneamente o fator de crescimento endotelial vascular (VEGF) e anti-CD34 em aço inoxidável 316L. Métodos: Placas de aço inoxidável 316L redondas no grupo DH foram polimerizadas com compostos gerados a partir da reacção de condensação de dopamina e heparina utilizando N- (3-dimetilaminopropil) -N'-etilcarbodiimida (EDC) e N-hidroxissuccinimida (NHS). Dezesseis folhas a partir do grupo DH foram ainda imersas em 1 ug/ml de VEGF 165 e 3 mg/ml de heparina sódica, um após outro por 10 vezes, sendo denominado como o grupo D-(HV)10. Oito folhas de D-(HV)10 foram revestidas com anticorpo anti-CD34 e denominado como grupo D-(HV)10-A. Testes de imunofluorescência e ELISA foram usados para avaliar se os discos de aço inoxidável 316L foram revestidos com sucesso com VEGF e anticorpo anti-CD34. Resultados: Os resultados dos testes de imunofluorescência e ELISA mostraram que o VEGF pôde ser detectado nos grupos D-(HV)10 e D-(HV)10-A, evidenciando que as chapas de aço foram cobertas com VEGF com sucesso. O anticorpo anti-CD34 podia apenas ser observado no grupo D-(HV)10-A, o único grupo revestido com anticorpo CD34. Ambos os resultados sugerem que as chapas de aço inoxidável 316L foram revestidas com sucesso com VEGF e anticorpo anti-CD34. Conclusão: Nosso estudo desenvolveu um método para revestir simultaneamente VEGF e anti-CD34 de aço inoxidável. Esta pesquisa tem um papel fundamental para a nova estratégia de revestimento. .

Stability of antimicrobial activity of peracetic acid solutions used in the final disinfection process

The instruments and materials used in health establishments are frequently exposed to microorganism contamination, and chemical products are used before sterilization to reduce occupational infection. We evaluated the antimicrobial effectiveness, physical stability, and corrosiveness of two commercial formulations of peracetic acid on experimentally contaminated specimens. Stainless steel specimens were contaminated with Staphylococcus aureus, Escherichia coli, Candida albicans, blood, and saliva and then immersed in a ready peracetic acid solution: 2% Sekusept Aktiv (SA) or 0.25% Proxitane Alpha (PA), for different times. Then, washes of these instruments were plated in culture medium and colony-forming units counted. This procedure was repeated six times per day over 24 non-consecutive days. The corrosion capacity was assessed with the mass loss test, and the concentration of peracetic acid and pH of the solutions were measured with indicator tapes. Both SA and PA significantly eliminated microorganisms; however, the SA solution was stable for only 4 days, whereas PA remained stable throughout the experiment. The concentration of peracetic acid in the SA solutions decreased over time until the chemical was undetectable, although the pH remained at 5. The PA solution had a concentration of 500-400 mg/L and a pH of 2-3. Neither formulation induced corrosion and both reduced the number of microorganisms (p = 0.0001). However, the differences observed in the performance of each product highlight the necessity of establishing a protocol for optimizing the use of each one.

Comparative study of friction between metallic and conventional interactive self-ligating brackets in different alignment conditions

OBJECTIVE: The aim of this study was to compare the friction between three bracket models: conventional stainless steel (Ovation, Dentsply GAC), self-ligating ceramic (In-Ovation, Denstply GAC) and self-ligating stainless steel brackets (In-Ovation R, Dentsply GAC). METHODS: Five brackets were used for each model. They were bonded to an aluminum prototype that allowed the simulation of four misalignment situations (n = 10). Three of these situations occurred at the initial phase (in which a 0.016-in nickel-titanium wire was used): 1. horizontal; 2. vertical; and 3. simultaneous horizontal/vertical. One of the situations occurred at the final treatment phase: 4. no misalignment (in which a 0.019 x 0.025-inch stainless steel rectangular wire was used). The wires slipped through the brackets and friction was measured by a Universal Testing Machine. RESULTS: Analysis of variance followed by Tukey's Test for multiple comparisons (α = 0.05) were applied to assess the results. Significant interaction (p < 0.01) among groups was found. For the tests that simulated initial alignment, Ovation(r) bracket produced the highest friction. The two self-ligating models resulted in lower and similar values, except for the horizontal situation, in which In-Ovation C(r) showed lower friction, which was similar to the In-Ovation R(r) metallic model. For the no misalignment situation, the same results were observed. CONCLUSION: The self-ligating system was superior to the conventional one due to producing less friction. With regard to the material used for manufacturing the brackets, the In-Ovation C(r) ceramic model showed less friction than the metallic ones. .

OBJETIVO: o objetivo desse trabalho in vitro foi comparar o atrito entre três modelos de braquetes: Ovation (convencional, aço inoxidável); In-Ovation C (autoligável, cerâmico) e In-Ovation R (autoligável, aço inoxidável), todos do mesmo fabricante (Dentsply GAC). MÉTODOS: para cada modelo, foram utilizados cinco braquetes, colados a um protótipo de alumínio, que permitiu a simulação de quatro situações (n = 10), sendo uma delas sem desalinhamento (com utilização de fio retangular de aço inoxidável, com espessuras de 0,019" x 0,025") e outras três com desalinhamento, sendo um horizontal, um vertical e outro simultaneamente combinando ambos (com utilização de fio de níquel-titânio com espessura de 0,016"). O atrito foi mensurado por uma máquina universal de ensaios. RESULTADOS: os resultados obtidos foram submetidos ao teste de Análise de Variância, complementado pelo teste de comparações múltiplas de Tukey (α = 0,05). Foi observada interação significativa entre os grupos (p < 0,01). Para os ensaios que simularam a fase inicial de alinhamento, realizada com fios de NiTi, o braquete Ovation foi o que produziu o maior atrito, e os dois modelos autoligáveis produziram resultados menores e semelhantes, exceto para o ensaio de desalinhamento horizontal, onde o In-Ovation C apresentou atrito menor do que o similar metálico In-Ovation R. Na fase em que o fechamento de espaço foi simulado, os mesmos resultados foram observados. CONCLUSÃO: pode-se concluir que o sistema de autoligável mostrou-se superior ao convencional, com elastômeros, por produzir menor atrito. Quanto ao material utilizado na confecção dos braquetes, o modelo cerâmico In-Ovation C apresentou menor atrito que os metálicos. .

Comparison of frictional resistance between self-ligating and conventional brackets tied with elastomeric and metal ligature in orthodontic archwires

OBJECTIVE: To compare the frictional resistance between self-ligating and conventional brackets tied to different types of wire. MATERIAL AND METHODS : Abzil Kirium Capelozza (Pattern I) and Easy Clip (Roth prescription) incisor brackets were used. An elastomeric ligature or a ligating wire 0.10-in was used to ligate the wire to the Abzil bracket. Three types of orthodontic archwire alloys were assessed: 0.016-in NiTi wire, 0.016 x 0.021-in NiTi wire and 0.019 x 0.025-in steel wire. Ten observations were carried out for each bracket-archwire angulation combination. Brackets were mounted in a special appliance, positioned at 90 degrees in relation to the wire and tested in two angulations. Frictional test was performed in a Universal Testing Machine at 5 mm/min and 10 mm of displacement. The means (MPa) were submitted to ANOVA and Tukey's test set at 5% of significance. The surfaces of wires and brackets were observed at SEM. RESULTS: Steel-tied brackets (16.48 ± 8.31) showed higher means of frictional resistance than elastomeric-tied brackets (4.29 ± 2.16 ) and self-ligating brackets (1.66 ± 1.57) (P < 0.05), which also differed from each other (P < 0.05). As for the type of wire, 0.019 x 0.025-in steel wire (5.67 ± 3.97) showed lower means (P < 0.05) than 0.16-in NiTi wire (8.26 ± 10.92) and 0.016 x 0.021-in NiTi wire (8.51 ± 7.95), which did not differ from each other (P > 0.05). No statistical differences (P > 0.05) were found between zero (7.76 ± 8.46) and five-degree (7.19 ± 7.93) angulations. CONCLUSIONS: Friction was influenced not only by the type of bracket, but also by the ligating systems. Different morphological aspects were observed for the brackets and wires studied .

OBJETIVO: comparar a resistência ao atrito entre braquetes autoligáveis e braquetes convencionais, variando o tipo de fio. MÉTODOS: foram usados braquetes incisivos Abzil Kirium Capelozza e Easy Clip. Uma ligadura elastomérica ou um fio ligável de 0,010" foi usado para ligação do fio no braquete Abzil. Três tipos de ligas de fio ortodôntico foram avaliadas: fio de NiTi de 0,016"; fio de NiTi de 0,016" x 0,022"; e fio de aço de 0,019" x 0,025". Dez observações foram feitas para cada combinação "braquete-fio-inclinação". Os braquetes foram montados em um aparelho especial, posicionados a 90° em relação ao fio, e testados em duas inclinações. O teste de atrito foi realizado na máquina universal de ensaios, a 5mm/min e com 10mm de deslocamento. As médias (em MPa) foram submetidas aos testes ANOVA e de Tukey, a 5% de significância. As superfícies dos fios e dos braquetes foram observadas no MEV. RESULTADOS: o braquete com amarrilhos metálicos (16,48 ± 8,31MPa) apresentou médias mais altas que o braquete com ligaduras elastoméricas (4,29 ± 2,16MPa) e o braquete autoligável (1,66 ± 1,57) (p < 0,05), os quais também diferiram entre si (p < 0,05). Quanto ao tipo do fio, o fio de aço de 0,019" x 0,025" (5,67 ± 3,97MPa) apresentou médias mais baixas (p < 0,05) que os fios de NiTi de 0,016" (8,26 ± 10,92MPa) e de 0,016" x 0,022" (8,51 ± 7,95), os quais não diferiram entre si (p > 0,05). Nenhuma diferença estatística (p > 0,05) foi encontrada entre inclinações de zero (7,76 ± 8,46) e cinco (7,19 ± 7,93) graus. Concluão: o atrito foi influenciado pelo tipo de braquete e sistemas de ligaduras. Diferentes aspectos morfológicos foram observados para os braquetes e fios estudados. .

Physical and chemical properties of orthodontic brackets after 12 and 24 months: in situ study

Objective: The aim of this article was to assess how intraoral biodegradation influenced the surface characteristics and friction levels of metallic brackets used during 12 and 24 months of orthodontic treatment and also to compare the static friction generated in these brackets with four different methods of the ligation of orthodontic wires. Material and Methods: Seventy premolar brackets as received from the manufacturer and 224 brackets that were used in previous orthodontic treatments were evaluated in this experiment. The surface morphology and the composition of the deposits found in the brackets were evaluated with rugosimetry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Friction was analyzed by applying tensile tests simulating sliding mechanics with a 0.019x0.025" steel wire. The static friction levels produced by the following ligation methods were evaluated: loosely attached steel ligature around all four bracket wings, steel ligature attached to only two wings, conventional elastomeric ligation around all 4 bracket wings, and non-conventional Slide® elastomeric ligature. Results: The results demonstrated the presence of biodegradation effects such as corrosion pits, plastic deformation, cracks, and material deposits. The main chemical elements found on these deposits were Carbon and Oxygen. The maximum friction produced by each ligation method changed according to the time of intraoral use. The steel ligature loosely attached to all four bracket wings produced the lowest friction levels in the new brackets. The conventional elastic ligatures generated the highest friction levels. The metallic brackets underwent significant degradation during orthodontic treatment, showing an increase in surface roughness and the deposit of chemical elements on the surface. Conclusion: The levels of static friction decreased with use. The non-conventional elastic ligatures were the best alternative to ...

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

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. .

Corrosion behavior of self-ligating and conventional metal brackets

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. .

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. .

Comparison of friction produced by two types of orthodontic bracket protectors

INTRODUCTION: Fixed orthodontic appliances have been regarded as a common causative factor of oral lesions. To manage soft tissue discomfort, most orthodontists recommend using a small amount of utility wax over the brackets in order to alleviate trauma. This in vitro study aimed at evaluating friction generated by two types of bracket protectors (customized acetate protector [CAP] and temporary resin protector [TRP]) during the initial stages of orthodontic treatment. METHODS: An experimental model (test unit) was used to assess friction. In order to measure the friction produced in each test, the model was attached to a mechanical testing machine which simulated maxillary canines alignment. Intergroup comparison was carried out by one-way ANOVA with level of significance set at 5%. RESULTS: The friction presented by the TRP group was statistically higher than that of the control group at 6 mm. It was also higher than in the control and CAP groups in terms of maximum friction. CONCLUSION: The customized acetate protector (CAP) demonstrated not to interfere in friction between the wire and the orthodontic bracket slot. .

INTRODUÇÃO: o aparelho ortodôntico fixo é considerado um fator causador de traumas na mucosa bucal. Com o intuito de controlar o desconforto no tecido mole, diversos ortodontistas recomendam a utilização de uma pequena quantidade de cera utilidade sobre os braquetes como forma de proteção. Esse estudo teve como objetivo avaliar, in vitro, o atrito gerado por dois tipos de protetores de braquetes (protetor de acetato e de resina - PPA e PRT) durante os estágios iniciais do tratamento ortodôntico. MÉTODOS: o atrito gerado pelos protetores no fio ortodôntico foi avaliado em unidades de teste de modelos experimentais. Esses modelos foram ligados a uma máquina de ensaios mecânicos que simulava o alinhamento do canino superior. A comparação intergrupos foi realizada pela ANOVA, com nível de significância de 5%. RESULTADOS: a fricção apresentada pelo grupo PRT foi estatisticamente maior do que a do grupo controle ao nível de 6mm. Para o atrito máximo, a média do grupo PRT foi estatisticamente maior do que a dos grupos controle e PPA. CONCLUSÃO: o protetor de acetato demonstrou não interferir no atrito entre o fio e a ranhura do braquete ortodôntico. .

Clinical evaluation of dental alignment and leveling with three different types of orthodontic wires

INTRODUCTION: A wide variety of orthodontic wires made of different alloys is available to be used in orthodontic practice and may produce different clinical responses during tooth movement. OBJECTIVE: This research evaluated the alignment and leveling of lower dental arches after the use of three types of orthodontic wires. METHODS: A sample of 36 patients was randomly divided into 3 groups: stainless steel, multistranded steel and superelastic nickel-titanium, according to the first leveling arches used. In order to observe differences in tooth position and axial inclination of the lower incisors, all patients had lateral cephalometric radiographs taken before the insertion of the first arches and 2 months later. The irregularity index and the curve of Spee were measured, compared between groups and considered influential on the proclination of incisors during the initial phase of alignment and leveling. The Reflex microscope was used to measure the irregularity index, whereas the ANOVA analysis of variance was used to verify differences between groups with regard to the degree of dental alignment and leveling. RESULTS: There were significant differences between groups only at T2 for the irregularity index. CONCLUSION: The NiTi and multistranded steel wires showed greater aligning capacity when compared with stainless steel wires.

INTRODUÇÃO: uma grande variedade de fios ortodônticos, compostos por diferentes ligas, está disponível para utilização ortodôntica, podendo gerar respostas clínicas diversas, durante a movimentação dentária. OBJETIVO: este trabalho visa a avaliar o alinhamento e nivelamento das arcadas dentárias inferiores, após a utilização de três tipos de fios ortodônticos. MÉTODOS: uma amostra de 36 pacientes foi aleatoriamente dividida em três grupos, de acordo com os primeiros arcos utilizados para o alinhamento e nivelamento: aço inoxidável convencional, aço multifilamentado e de níquel-titânio superelástico. Para se avaliar as diferenças relacionadas ao posicionamento dentário e inclinação axial dos incisivos inferiores, foram obtidas radiografias cefalométricas de perfil, de todos os pacientes, em duas fases do tratamento: antes da inserção dos primeiros arcos e dois meses após a inserção dos mesmos. O índice de irregularidade dentária (IID) e a profundidade inicial de curva de Spee, fatores influentes sobre a projeção de incisivos durante a fase inicial de alinhamento e nivelamento, foram avaliados e comparados intra- e intergrupos. Para a medição do IID, foi utilizado o Reflex Microscope, possibilitando a mensuração do grau de alinhamento e nivelamento dentário em terceira dimensão. A análise de variância (ANOVA) foi utilizada para se avaliar as diferenças intergrupos em relação ao grau de alinhamento e nivelamento dentário. RESULTADOS: diferenças estatisticamente significativas intergrupos somente foram encontradas em T2, em relação ao índice de irregularidade dentária, já que os fios de NiTi e aço multifilamentado apresentaram maior capacidade de alinhamento do que os fios de aço inoxidável convencionais.

Pain, masticatory performance and swallowing threshold in orthodontic patients

OBJECTIVE: The aim of this study was to assess pain, masticatory performance and swallowing threshold of patients undergoing orthodontic treatment. METHODS: Ten patients of both genders (mean age of 17.25 ± 5.21 years), with complete permanent dentition, who underwent orthodontic treatment with fixed appliances were evaluated. The masticatory performance and the swallowing threshold were assessed by patient's individual capacity of fragmenting an artificial test food (Optocal) which was chewed and had the resulting particles processed by a standardized sieving method, presenting the median particle size (MPS) of crushed units. The intensity of pain / discomfort during chewing was evaluated by means of a visual analog scale. All tests were performed at the following times: T0 - before activating the orthodontic appliance; T1 - 24 hours after activation, and T2 - 30 days after activation. RESULTS: The results showed a significant increase in pain at T1 (T0 - 0.60 ± 0.70 mm; T1 - 66.2 ± 34.5 mm), returning to baseline values at T2 (3.20 ± 3.82 mm). Masticatory performance was also reduced in T1 (MPS 10.15 ± 1.1 mm²) in comparison to T0 (MPS 7.01 ± 2.9 mm²) and T2 (MPS 6.76 ± 1.3 mm²). However, particle size was not affected in the swallowing threshold test (T0 - 5.47 ± 2.37 mm²; T1 - 6.19 ± 2.05 mm²; T2 - 5.94 ± 2.36 mm²). CONCLUSION: The orthodontic appliances did not interfere in the size of the particles that would be swallowed, even in the presence of pain.

OBJETIVO: o objetivo desse estudo foi avaliar a dor, a performance mastigatória e o limiar de deglutição em pacientes submetidos ao tratamento ortodôntico. MÉTODOS: foram avaliados dez pacientes de ambos os sexos (idade média 17,25 ± 5,21 anos), com dentição permanente completa, submetidos ao tratamento ortodôntico com aparelhos fixos. A performance mastigatória e o limiar de deglutição foram avaliados pela capacidade individual de fragmentação de um alimento teste artificial (Optocal), o qual foi mastigado e as partículas resultantes processadas por um método padronizado com peneiras, apresentando o tamanho mediano das partículas (TMP) das unidades trituradas. A intensidade da dor/desconforto foi avaliada com o uso de uma escala analógica visual. Todos os testes foram realizados nos seguintes momentos: T0: antes da ativação do aparelho ortodôntico; T1: 24 após a ativação, e T2: 30 dias após a ativação. RESULTADOS: os resultados demonstraram um aumento significativo na dor em T1 (T0: 0,60 ± 0,70mm; T1: 66,2 ± 34,5mm), retornando aos valores basais em T2 (3,20 ± 3,82mm). A performance mastigatória também foi reduzida em T1 (TMP: 10,15 ± 1,1mm²) comparada a T0 (TMP: 7,01 ± 2,9mm²) e T2 (TMP = 6,76 ± 1,3 mm²). Entretanto, o tamanho das partículas não foi afetado no teste do limiar de deglutição (T0: 5,47 ± 2,37mm²; T1: 6,19 ± 2,05mm²; T2: 5,94 ± 2,36mm²). CONCLUSÃO: os aparelhos ortodônticos não interferiram no tamanho das partículas que seriam deglutidas, mesmo na presença da dor.

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

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. .

Mechanical evaluation of quad-helix appliance made of low-nickel stainless steel wire

OBJECTIVE: The objective of this study was to test the hypothesis that there is no difference between stainless steel and low-nickel stainless steel wires as regards mechanical behavior. Force, resilience, and elastic modulus produced by Quad-helix appliances made of 0.032-inch and 0.036-inch wires were evaluated. METHODS: Sixty Quad-helix appliances were made, thirty for each type of alloy, being fifteen for each wire thickness, 0.032-in and 0.036-in. All the archwires were submitted to mechanical compression test using an EMIC DL-10000 machine simulating activations of 4, 6, 9, and 12 mm. Analysis of variance (ANOVA) with multiple comparisons and Tukey's test were used (p < 0.05) to assess force, resilience, and elastic modulus. RESULTS: Statistically significant difference in the forces generated, resilience and elastic modulus were found between the 0.032-in 0.036-in thicknesses (p < 0.05). CONCLUSIONS: Appliances made of low-nickel stainless steel alloy had force, resilience, and elastic modulus similar to those made of stainless steel alloy.

OBJETIVO: o objetivo do presente estudo foi testar a hipótese de não haver diferença no desempenho mecânico entre fios de aço inoxidável e fios de aço inoxidável com baixo teor de níquel. Avaliar, também, a força, a resiliência e o módulo de elasticidade produzidos pelos aparelhos quadri-hélice confeccionados com fio de 0,032" e 0,036". MÉTODOS: foram confeccionados 60 aparelhos quadri-hélice. Desses, 30 para cada tipo de liga, sendo 15 confeccionados com fio de 0,032" e 15 com fio 0,036". Todos os arcos foram submetidos a teste de compressão mecânica em máquina EMIC DL-10000, simulando 4, 6, 9, e 12mm de ativação. A análise de variância e comparação múltipla (ANOVA) e o teste de Tukey foram utilizados (p < 0,05) para avaliação da força, resiliência e módulo de elasticidade. RESULTADOS: observou-se diferença estatisticamente significativa entre forças produzidas, resiliência e módulo de elasticidade entre as espessuras 0,032" e 0,036" (p < 0,05). CONCLUSÃO: os aparelhos confeccionados com liga de aço inoxidável com baixo teor de níquel apresentaram liberação de força, resiliência e módulo de elasticidade semelhantes aos aparelhos que utilizaram a liga de aço inoxidável.