Abstract
OBJETIVO: o processo de solda envolve íons metálicos capazes de provocar lise celular. Diante disso, o objetivo deste estudo foi testar a hipótese de que existe citotoxicidade entre diferentes tipos de ligas (CrNi, TMA, NiTi) utilizadas em Ortodontia, submetidas à solda elétrica a ponto. MÉTODOS: três tipos de ligas foram avaliados neste estudo. Foram confeccionados 36 corpos de prova, 6 para cada combinação entre os fios, divididos em 6 grupos - grupo AA (aço com aço), grupo AT (aço com TMA), grupo AN (aço com NiTi), grupo TT (TMA com TMA), grupo TN (TMA com NiTi) e grupo NN (NiTi com NiTi) - que foram submetidos à solda a ponto para avaliação quanto ao possível efeito citotóxico nos tecidos bucais. Previamente, os corpos de prova foram limpos com álcool isopropílico e esterilizados em luz ultravioleta. O ensaio de citotoxicidade foi realizado utilizando-se cultura de células (linhagem L929, fibroblastos de camundongos), submetida ao teste para células viáveis em vermelho neutro ("dye-uptake") no tempo de 24h. A análise de variância e comparação múltipla (ANOVA) e teste de Tukey foram utilizados (p< 0,05). RESULTADOS: os resultados demonstraram que não houve diferença estatisticamente significativa entre os grupos experimentais (P> 0,05). Foi observada maior viabilidade celular no grupo TT, seguido dos grupos AT, TN, AA, NA e NN. CONCLUSÃO: pôde-se evidenciar que solda em fios de liga de NiTi causaram maior quantidade de lise celular. Soldas elétricas a ponto demonstraram pequena capacidade de causar lise celular.
Highlights
The test specimens were fabricated with rectangular wires (0.019x0.025-in), cut into segments of 25 mm, which were welded using combinations between stainless steel (CrNi), nickel-titanium (NiTi) and molybdenum-titanium (TMA) wires (Morelli, Sorocaba, Brazil)
Data were compared by analysis of variance (ANOVA) and Tukey’s test for assessment between groups, with reliability set at 5% significance level
Attempts have been made to replace it with other welding methods27,28 — such as electric spot welding — that are free from the metal ions present in silver solder.[13,22,26,17,27,28]
Summary
This study used a culture of L929 cells (mouse fibroblasts) obtained from the American Type Culture Collection (ATCC, Rockville, MD, USA), maintained in Eagle minimum essential medium (MEM-Eagle) (Cultilab, Campinas, Brazil) plus 0.03 mg/ml glutamine After 24 hours of incubation, 100 μl of neutral red at 0.01% were added (Sigma, St. Louis, Missouri, USA), in a culture medium, to the microplate wells and these were incubated at 37°C for 3 hours to allow penetration of vital dye into the living cells. Missouri, USA), in a culture medium, to the microplate wells and these were incubated at 37°C for 3 hours to allow penetration of vital dye into the living cells After this period and after disposal of the dye, 100 μl of formaldehyde solution (Reagen) at 4% were added in PBS (NaCl 130 mM; KCl 2 mM; Na2HPO4 2H2O 6 mM; K2HPO4 1mM, pH 7.2) for 5 minutes to promote cell attachment to the plates. Data were compared by analysis of variance (ANOVA) and Tukey’s test for assessment between groups, with reliability set at 5% significance level
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