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  • 1
    In: Materials, MDPI AG, Vol. 12, No. 20 ( 2019-10-09), p. 3279-
    Abstract: Many advantages have been described surrounding self-ligating (SL) brackets compared to metallic conventional ligating (CL) brackets, such as: Less total treatment time, alignment efficiency, patient comfort, plaque retention, and low friction. The objective of this in vitro simulation was to know the variables that affect arch displacement in CL and SL brackets—active (ASL) and passive (PSL)—and analyze if static friction values are affected by bracket design, arch wire section, kind of ligature, and use of a friction reducer agent (FRA) in a wet state. Larger values of static friction were found in CL with metallic ligature (ML) (8.01 ± 1.08 N/mm) and elastic ligature (EL) (6.96 ± 0.48 N/mm). Lower values were found in PSL brackets combined with FRA (0.58 ± 0.21 N/mm). The study was carried out using different stereographical models of a maxillary upper right quadrant with canine, first and second premolar, and first molar bonded brackets. A section of 25 mm of 0.019 × 0.025” stainless steel arch with a rectangular section (SS) and hybrid section (HY) was inserted into the different bracket models. Static friction values were collected using a universal test machine in wet conditions and testing the effect of a friction reducer agent (FRA). To assure the reliability of the study, different wire combinations were repeated after two weeks by the same operator and a linear analysis of regression was done. Each bracket model analysis—with the different wires, use of the FRA, and comparison among brackets in similar conditions—was done using an ANOVA test with a confidence interval of 95% and comparative Post-Hoc tests (LSD). In this in vitro simulation we found higher static friction values in CL compared to ASL and PSL. In PSL, lower values were achieved. CL brackets using ML showed the highest static friction values with a great variability. In this setting, the use of HY wires did not reduce static friction values in ASL and PSL, while in CL brackets with EL friction the values were reduced significantly. An FRA combined with ASL reduced significantly static friction values but not with PSL. In the case of CL, the FRA effect was higher with SS and better than with HY wires. ML values were similar to ASL static friction. The direct extrapolation of the results might be inaccurate, since all these findings should be tested clinically to be validated.
    Type of Medium: Online Resource
    ISSN: 1996-1944
    Language: English
    Publisher: MDPI AG
    Publication Date: 2019
    detail.hit.zdb_id: 2487261-1
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  • 2
    In: Metals, MDPI AG, Vol. 10, No. 6 ( 2020-05-26), p. 702-
    Abstract: A potential new bactericide treatment for NiTi orthodontic archwires based in the electrodeposition of silver nanoparticles on the surface was studied. Twenty-five archwires were treated by electrodeposition, obtaining nanoparticles of silver embedded on the archwire surface. These were evaluated in order to investigate the possible changes on the superelastic characteristics (critical temperatures and stresses), the nickel ion release, and the bacteria culture behavior. The chemical composition was analyzed by Energy Dispersive X-Ray Spectroscopy-microanalysis; the singular temperatures of the martensitic transformation were obtained by a flow calorimeter. Induced martensitic transformation stresses were obtained by mechanical testing apparatus. Nickel ion release was analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) equipment using artificial saliva solution at 37 °C. Bacterial tests were studied with the most used oral bacterial strains: Streptococcus sanguinis and Lactobacillus salivarius. NiTi samples were immersed in bacterial suspensions for 2 h at 37 °C. Adhered bacteria were separated and seeded on agar plates: Tood-Hewitt (TH) and Man-Rogosa-Sharpe (MRS) for S. sanguinis and for L.salivarius, respectively. These were then incubated at 37 °C for 1 day and the colonies were analyzed. The results showed that the transformation temperatures and the critical stresses have not statistically significant differences. Likewise, nickel ion release at different immersion times in saliva at 37 °C does not present changes between the original and treated with silver nanoparticles archwires. Bacteria culture results showed that the reduction of the bacteria due to the presence to the nanoparticles of silver is higher than 90%. Consequently, the new treatment with nanoparticles of silver could be a good candidate as bactericidic orthodontic archwire.
    Type of Medium: Online Resource
    ISSN: 2075-4701
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2662252-X
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  • 3
    In: Dental Press Journal of Orthodontics, FapUNIFESP (SciELO), Vol. 25, No. 1 ( 2020-01), p. 47-55
    Abstract: RESUMO Introdução: Já foram enumeradas diversas vantagens quanto à eficiência dos braquetes autoligáveis (BAL). Apesar das controvérsias na literatura, resultados clínicos confirmam que o “desenvolvimento da arcada” demanda menos extrações. Objetivo: O objetivo deste estudo foi comparar as mudanças nos planos transversal e sagital em pacientes tratados com braquetes convencionais (BC) e pacientes tratados com BAL e arcos superdimensionados. Métodos: A amostra foi selecionada de um grupo de 300 pacientes tratados consecutivamente por um mesmo ortodontista: 51 pacientes com BAL e arcos superdimensionados, e 55 com BC. Esses dois grupos foram comparados a um grupo controle (GC) de 20 pacientes. Todos os modelos de gesso foram escaneados e pontos de referência dentários foram mensurados, para se identificar as mudanças entre o início (T0) e o fim do tratamento (T1). Radiografias cefalométricas laterais foram analisadas para identificar mudanças nos incisivos inferiores (IMPA) e na angulação distal dos primeiros molares inferiores (MAng). A confiabilidade intraexaminador foi testada por meio de uma análise de regressão linear. Para garantir que os grupos fossem comparáveis em T0, realizou-se o teste ANOVA com intervalo de confiança (IC) de 95% para todos os valores. Para avaliar as mudanças entre T0 e T1 em todos os grupos, foi utilizado o teste t de Student com IC de 95%. Por fim, os resultados dos três grupos foram comparados utilizando-se o teste ANOVA (IC 95%) e um teste post-hoc. Resultados: Foram registrados aumentos em todas as variáveis transversais nos dois grupos tratados (BC e BAL), com exceção da distância intercaninos inferiores no grupo BAL. As maiores diferenças de T0 para T1 ocorreram no IMPA do grupo BC e na angulação distal de molares (MAng) do grupo BAL. Conclusões: Ambos os grupos, BAL com arcos superdimensionados e BC, apresentaram aumento em todas as variáveis no plano transversal, com exceção da distância intercaninos inferiores no grupo BAL. Em comparação ao grupo BC, menores diferenças nos valores de IMPA foram observadas no grupo BAL, no qual aconteceu angulação distal de molares.
    Type of Medium: Online Resource
    ISSN: 2177-6709 , 2176-9451
    Language: English
    Publisher: FapUNIFESP (SciELO)
    Publication Date: 2020
    detail.hit.zdb_id: 2721511-8
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