Nickel and Chromium Ion Levels in Hair and Gingival Crevicular Fluid with the Corrosion of Brackets in Orthodontic Patients: A Longitudinal Study

Objective: To assess the levels of nickel and chromium ions in hair and Gingival Crevicular Fluid (GCF) of orthodontic patients and to evaluate the corrosion of orthodontic bracket surfaces. Material and Methods: Nickel and chromium ion concentrations were measured in hair and GCF of 15 patients (9 females and 6 males, aged 16-28 years old) who had fixed orthodontic treatment using atomic absorption spectroscopy. The samples were taken before treatment (baseline), 4, 8, and 16 months later during treatment. Along with ionic sampling, microscopic sampling was done. One of each patient brackets was removed to get 15 brackets per group. Five brackets were taken randomly from each group to be examined under scanning electron microscope (SEM). Data obtained were analyzed using paired t-tests. Results: After 16 months, compared with the baseline, average hair nickel level changed from 0.125 µg/g to 0.956 µg/g with statistically significant difference (p=0.00); average chromium level changed from 0.090 µg/g to 0.295 µg/g but no significant difference (p>0.05); average GCF nickel level changed from 3.335 µg/g to 10.410 µg/g; average chromium level changed from 1.859 µg/g to 9.818 µg/g. Both of these increases were significant (p=0.000). SEM examinations showed that the corrosion on brackets was seen in the fourth month, and more severely visible after 8 and 16 months of uses. Conclusion: After 16 months of treatment, compared with the baseline, the hair nickel level was increased by 7.7 times; while for chromium was by 3.3 times. Gingival crevicular fluid nickel level was increased by 3.1 times and chromium level was by 5.3 times. The longer time of treatment, the more ions released and the more corrosion of brackets will be.

Corrosion Resistance of Stainless Steel Brackets After Thermal Recycling by Direct Flaming

Objective: To determine and compare the corrosion resistance (based on the release of nickel and chromium in artificial saliva) of various brands of stainless steel brackets after thermal recycling by direct flaming. Material and Methods: This research study employed 40 stainlesssteel maxillary premolar brackets from different brands (Ormco, GAC, Versadent, S-Ortho, and Protect), which were divided into 5 groups consisting of 8 brackets. The nickel and chromium content of the metal brackets were analyzed by inductively coupled plasma mass spectrometry (ICP-MS), conducted before immersion. For the first treatment, each group was immersed in artificial saliva without direct flaming (recycling); for the second treatment, each group was immersed in artificial saliva with direct flaming (recycling) for 30 days in a pH-neutral (pH=7) solution. ICP-MS was employed to analyze the nickel and chromium released in saliva. The mean differences were measured with Wilcoxon, Kruskal Wallis test, and Post-Hoc Mann Whitney test. Differences were considered statistically significant when p-value<0.05. Results: The mean corrosion resistance based on the nickel content released by the new brackets was 99.95%, 99.87%, 87.09%, 90.58%, and 90.26% for groups A, B, C, D, and E, respectively. The mean corrosion resistance based on the nickel content released by the recycled brackets was 99.90%, 99.80%, 98.19%, 89.76%, and 72.82%, respectively. There was a significant difference in corrosion resistance among the 5 groups after recycling by direct flaming and between new and recycled brackets in each group. Conclusion: The corrosion resistance of the brackets in groups A (Ormco), B (GAC), D (S-Ortho), and E (Protect) decreased after thermal recycling by direct flaming. The Ormco brackets had the highest corrosion resistance after thermal recycling by direct faming.

Comparison Between Nickel and Chromium Levels in Serum and Urine in Patients Treated with Fixed Orthodontic Appliances: A Longitudinal Study

Objective: To compare levels of nickel and chromium in serum and urine in orthodontic patients treated with fixed orthodontic appliances. Material and Methods: Nickel and chromium ion concentration were measured in serum and urine of twenty patients (12 females and 8 males, aged 17-28 years old) who had fixed orthodontic treatment using Coupled Plasma-Atomic Emission Spectroscopy. The samples were taken before treatment (Baseline), two months, and six months later during treatment. Data were analyzed using repeated ANOVA, Bonferroni post-hoc test, and paired t-tests. The level of significance was set at 5%. Results: Average serum nickel level changed from 6.420 ppb to 6.855 ppb. Average serum chromium level changed from 5.305 ppb to 5.505 ppb in 6 months. Average urinary nickel level changed from 5.320 ppb to 5.610 ppb. Average urinary chromium level changed from 5.370 ppb to 5.520 ppb in 6 months. There was a statistically significant difference in serum (p<0.001) and urinary chromium (p=0.007) levels between observation times. Conclusion: Orthodontic treatment might raise both urinary and serum nickel levels, but the differences were not statistically significant; the alterations in chromium levels were not consistent; nickel levels were higher in serum than in urine; chromium levels were higher in urine than in serum.

Avaliação comparativa dos níveis de desajustes marginais de pilares UCLAS calcináveis assentados sobre a plataforma de implantes e sobre pilar cônico em próteses fixas implantosuportadas / Comparative assessment of the levels of marginal misfits UCLAS calcinable pillars seated on the platform and on implant abutment conical

Este trabalho objetivou avaliar os níveis de desajustes marginais de infraestruturas metálicas em próteses fixas assentadas sobre pilar cônico pré-fabricado (estheticone) e diretamente sobre o hexagonal do implante. Foram obtidas quatro amostras de infraestruturas de próteses fixas fundidas em liga de Níquel-Cromo assentadas sobre análogos de implantes regulares e sobre análogos do pilar cônico. As infraestruturas foram distribuídas em dois grupos (n=2) experimentais. Os desajustes marginais verticais (µm) foram avaliados com o emprego de um microscópio mensurador digital. Cada amostra recebeu quatro marcações diametralmente opostas (mesial, distal, vestibular e lingual) e foram avaliadas três vezes em cada uma dessas superfícies com o parafuso de fixação devidamente adaptado. Para a análise estatística foi utilizado o teste de U Mann Whitney na correlação dos valores das quatro faces diametralmente opostas (mesial, distal, vestibular e lingual) de ambos os grupos. Ainda, utilizou-se o teste Kruskal-Wallis para correlacionar os valores obtidos entre os pilares empregados. Os resultados mostraram que não houve diferença estatisticamente significante no desajuste marginal entre os grupos comparados. Concluiu-se que não houve diferença no desajuste marginal de infraestruturas metálicas de próteses sobre implantes fundidas com ligas de Ni-Cr com UCLA assentados sobre pilar estheticone ou diretamente sobre o hexágono de um implante de plataforma regular (AU).

The objective of this work was to evaluate the levels of marginal mismatches of metallic infrastructures on fixed prostheses seated on the following types of platforms: pre-fabricated conical pillar (estheticone), pillar UCLA, and directly on the hexagonal of the implant. Samples of infrastructures of fixed prostheses made of nickel-chrome alloy and seated on similar regular implants and on similar conical pillar were used. The infrastructures were distributed in two experimental groups (pillar estheticone and direct pillar on the platform). For the evaluation of vertical marginal mismatches (µm), each sample was seated on its platform and observed with the aid of a digital measuring microscope. Each sample received four marks, diametrically opposite to each other (mesial, distal, vestibular, and lingual) and all samples were evaluated three times in each surface with the fixation screw properly adapted. The averages of these evaluations were obtained using U Mann Whitney and Kruskal-Wallis statistical tests. The result of the U Mann Whitney test,did not show significant statistical difference while Kruskal-Wallis test showed difference between the estheticone pillar and the UCLA pillar. The estheticone pillar showed lower mismatches averages than the UCLA pillar and, no significant statistical difference was observed in the comparison with the hexagonal platform of the implant (AU).

Estudo comparativo das forças geradas por alças ortodônticas / Comparative study of forces devivered by orthodontic loops

O objetivo desta pesquisa foi determinar as forças liberadas por arcos com alças produzidos industrialmente e, ainda, compará-los agrupando-os de forma a isolar uma única variável (geometria, liga metálica e fabricante). Foram utilizados 19 tipos diferentes de arcos, submetidos a testes de tração. Os resultados demonstraram diferenças estatísticas significativas entre todosos grupos comparados. A combinação destas variáveis pode determinar incrementos ou decréscimos nas forças liberadas, julgando-se útil fornecer ao ortodontista um guia de orientação para a escolha do arco adequado.

This research’s objective was to determine forces delivered by arches with industrially manufactured loops and to compare them in groups, changing one variable at a time (geometry, metal alloy and manufacturer). Nineteen different types of arches were submitted to tension tests. Results showed significant statistical differences between groups compared. The combination of these variables may determine increases or decreases in forces delivered and can be a useful guide for orthodontists when choosing proper arches.

Reaçöes aos metais utilizados em ortodontia / Hypersensibility to orthodontic metals appliance

Estudo clínico e experimental da incidência de hipersensibilidade a metais dos aparelhos ortodônticos e das consequências morfológicas da absorçäo do níquel. Realizaram-se testes de contato, antes e dois meses após a colocaçäo de aparelhos, em 38 pacientes, utilizando-se como antígenos o cloreto e cobalto, sulfato de cobre, bicromato de potássio, sulfato de ferro, cloreto de manganês, sal de molibdênio, sulfato de níquel e óxido de titânio. Concluiu-se que: manganês, cromo e níquel apresentaram positividade, estatisticamente significativa, com prevalência de 21,1 por cento para os dois últimos matais. Näo houve diferença estatisticamente significativa no resultado do teste de contato em relaçäo ao sexo e ao aparelho (antes ou depois). Avaliou-se, através de espectroscopia de absorçäo atômica, a quantidade de níquel na urina de 21 pacientes, nestes dois momentos, constatando-se aumento da mesma após a montagem do aparelho, näo havendo diferença estatística entre os sexos. A avaliaçäo experimental foi realizada em 26 camundongos (Swiss webster), divididos em dois grupos controle (C14 e C45) e dois grupos níquel (N14 e N15), que receberam aplicaçäo subcutânea de sulfato de níquel, sendo sacrificados após 15 e 46 dias. Constatou-se, no grupo experimental, aumento de peso total e de alguns órgäos, lesäo microscópica em órgäos hematopoiéticos, coraçäo, fígado e rins, mais evidente em N45. Nefrotoxicidade foi evidenciada por modificaçäo no padräo de ligaçäo às lectinas. No fígado, a análise estereológica demonstrou aumento do volume dos hepatócitos e de seus núcleos. Näo se dectou quantidades mensuráveis de níquel ao micrscópio eletrônico de varredura com raios X por energia dispersa (EDS)

Corrosäo em limas endodônticas de aço inoxidável / Corrosion of inoxidable endodontical files

Seis marcas comerciais de limas endodônticas foram utilizadas neste trabalho. As amostras foram analisadas no microscópio eletrônico de varredura (MEV), marca JEOL, modelo JSM U-3, para a avaliaçäo qualitativa da corrosäo após a imersäo em soluçäo esterilizadora (Germekil) e em soluçäo de hipoclorito de sódio com concentraçäo de 4 a 6 por cento. Fez-se a análise química semi-quantitativa das amostras utilizando-se uma micro-sonda acoplada ao MEV. Os resultados revelaram que as limas endodônticas säo fabricadas com aço austenítico do tipo 18-8, apresentam corrosäo por pites quando imersas em hipoclorito de sódio e resistência ao ataque por Germekil

Ligas ortodônticas correntemente em uso: revisão (Parte I) / Alloys currently used in Orthodontics: a review (Part I)

Revisão sobre as ligas ortodônticas corretamente em uso, em duas partes. Nesta primeira parte são abordados os tipos de testes de laboratório com os fios, salientando as propriedades de relevância clínica. As ligas consideradas são as de aço inoxidável, cromo-cobalto, níquel-titânio e beta-titânio

Ligas ortodônticas correntemente em uso: revisão (Parte II) / Alloys currently used in Orthodontics: a review (Part II)

Os princípios de seleção dos fios ortodônticos são revistos à luz das propriedades únicas dos materiais. A seguir é enfatizado o conceito de módulo variável em Ortodontia