Bypass de instrumento endodôntico fraturado: relato de caso / Bypass of a fractured endodontic instrument: case report

Introdução: Mesmo com toda evolução tecnológica desses instrumentos, com o desenvolvimento das limas de liga de níquel-titanio (NiTi) e sistemas mecanizados, as fraturas podem ocorrer durante o preparo químico/mecânico. Existem três abordagens mais regulamente aplicadas para solucionar essa intercorrencia: tentativa de remoção do instrumento com ultrassom, tentativa de ultrapassálo (bypass) ou a obturação do segmento. Objetivo: Relatar um caso da técnica de bypass em instrumento fraturado no canal radicular. Descrição do caso: Paciente, sexo feminino, 47 anos, brasileira, sem condições sistêmicas associadas, foi encaminhada à clínica do Curso de Odontologia da UNIFENAS, Divinópolis, Minas Gerais, Brasil, para resolução de fratura de instrumento no canal mésio- vestibular do primeiro molar superior direito (16). Optou-se pelo tratamento pela técnica de bypass, que envolveu as seguintes etapas: anestesia, abertura, utilização de lima C-Pilot #08 para ultrapassar o instrumento fraturado, odontometria, escalonamento regressivo a partir da lima k#20, desinfecção com hipoclorito de sódio 5%, medicação com hidróxido de cálcio por 21 dias, agitação da substância irrigadora e obturação dos canais radiculares. Conclusão: O bypass ao instrumento é uma técnica conservadora, eficaz e uma solução adequada em casos de fratura de limas endodônticas dentro dos canais radiculares. Essa técnica visa preservar o máximo possível da estrutura dental original, evitando procedimentos mais invasivos.(AU)

Introduction: Even with all technological evolution of these instruments, with the development of nickel-titanium alloy (NiTi) files and mechanized systems, fractures can occur during chemical/mechanical preparation. There are three most commonly applie to resolve this complication: attempting to remove the instrument with ultrasound, attempting to bypass it, or obturating the segment. Objective: To report a case of bypass technique in fractured instrument in the root canal. Case description: A 47-year-old female patient from Brazil, with no associated systemic conditions, was referred to the clinic of the Dentistry Course at UNIFENAS, Divinópolis, Minas Gerais, Brazil, for resolution of an instrument fracture in the mesio-vestibular canal of the right upper first molar (16). Treatment was performed using the bypass technique, which involved the following steps: anesthesia, opening, use of a C-Pilot #08 file to bypass the fractured instrument, odontometry, regressive scaling from the k#20 file, disinfection with 5% sodium hypochlorite, medication with calcium hydroxide for 21 days, agitation of the irrigating substance and root canal filling. Conclusion: Instrument bypass is a conservative, effective technique and an adequate solution in cases of endodontic file fracture within root canals. This technique aims to preserve as much of the original tooth structure as possible, avoiding more invasive procedures.(AU)

Câncer nasal e dos seios paranasais relacionados à saúde ocupacional / Nasal and paranasal sinus cancer related to occupational health

Resumo: Esta pesquisa, apresentada no formato de artigo, está inserida na linha de pesquisa Processo de Cuidar em Saúde e Enfermagem, do Programa de Pós-Graduação em Enfermagem, e integra o Grupo de Pesquisa Multiprofissional em Saúde do Adulto da Universidade Federal do Paraná. Introdução: o câncer nasal e dos seios paranasais corresponde a menos de 1% dos demais tipos de câncer, com fatores etiológicos decorrentes do meio ambiente, das atividades ocupacionais e dos hábitos de vida, com período de latência que pode variar até 20 anos para o aparecimento dos sintomas neoplásicos. Objetivos: caracterizar o perfil sociodemográfico, clínico e ocupacional dos brasileiros com câncer nasossinusal; traduzir, adaptar culturalmente e validar o Questionario Sulla Storia di Lavoro e Sulle Abitudini di Vita utilizado pelo Registro Tumori Seni Nasali e Paranasali da Lombardia, Itália, para o contexto cultural brasileiro; examinar o perfil sociodemográfico, clínico e ocupacional dos pacientes com câncer nasossinusal e relacionar a ocupação com a exposição ao pó de couro, lenha, cromo e níquel. Artigo 1: é um estudo observacional, descritivo e retrospectivo, utilizando os dados secundários do Integrador de Registro Hospitalar de Câncer no período de 2007 a 2019, com os CIDs: C30.0 e C31.0 a C31.9. Foram analisados 1.803 registros e destacou-se que 1.161 (64%) eram do sexo masculino, com faixa etária predominante entre 50 e 59 anos (26%; n=298), da raça/cor branca (46%; n=535), solteiros (55%; n=640) e com ensino fundamental incompleto (40%; n=461), que tinham incidência da neoplasia no seio maxilar (52%; n=943), com estadiamento clínico grau IV (32%; n=575). A ocupação foi registrada nos brasileiros com câncer nasossinusal no Grupo 6 (64,7%; n=701) - trabalhadores agropecuários, florestais e da pesca, e no Grupo 8 (26,7%; n=289) - trabalhadores da produção de bens e serviços industriais, principalmente no Estado da Bahia (11%; n=206) e Minas Gerais (18%; n=327). Artigo 2: descreve um estudo metodológico com as etapas de tradução, síntese, retrotradução, relatório de retrotradução, revisão, teste piloto e tradução final proposto pelo European Organisation for Research and Treatment of Cancer. O instrumento foi dividido em 11 domínios conforme a característica das perguntas do instrumento original. O pré-teste foi realizado num hospital de referência em oncologia do Estado do Paraná, Brasil, com 15 participantes que foram os pacientes com câncer nasal e dos seios paranasais e cinco familiares, entre julho e setembro de 2021. O instrumento obteve um índice de 94% de concordância entre os juízes, que fizeram sugestões de inclusão, manutenção semântica e substituição em 11 domínios. No pré-teste os participantes fizeram confirmação do entendimento sobre as perguntas e os domínios de 100% (n=15), entretanto, todos tiveram dificuldade de interpretação da palavra "popper", e 53% (n= 8) fizeram proposições de melhoria no questionário. Um participante solicitou a inclusão do narguilé nos hábitos de fumo. Artigo 3: consiste num relato de séries de casos de um hospital de oncologia do Estado do Paraná, no Sul do Brasil, no período de 2005 a 2021. Foram incluídos pacientes com idade acima de 18 anos, de ambos os sexos, com CID C30 e o grupo C31, que estavam em acompanhamento de saúde nos últimos 12 meses na instituição hospitalar, ou familiares (no caso de óbito do paciente) com idade superior ou igual a 18 anos. Os participantes foram entrevistados com o Questionário sobre o Histórico de Trabalho e os Hábitos de Vida, com os dados obtidos analisados por frequência simples e absoluta Resultados: O Artigo 3 teve 52 participantes eram do sexo masculino (56%; n= 29), casados (31%; n= 16), com ensino fundamental completo (23%; n= 12) e sem histórico de tabagismo (27%; n= 14), onde a localização prevalente foi C30.0 em homens (33%; n=17) com carcinoma de células escamosas (40,3%; n= 21). A exposição carcinogênica com poeira da madeira (29,8%; n=17), cromo e níquel (17,5%; n=10) e com couro e derivados (14%; n=8). Conclusão: a frequência do câncer nasal e dos seios paranasais foi maior no sexo masculino, com ensino fundamental, nos trabalhadores agropecuários e da indústria de transformação e tiveram exposição ao agente carcinogênico; o estudo poderá motivar as reflexões acerca do acometimento do câncer nasal e dos seios paranasais no contexto brasileiro, principalmente de origem ocupacional, conforme as monografias do International Agency for Research on Cancer, que enfatiza a importância de utilizar um instrumento de investigação com informações complexas e essenciais do histórico ocupacional e dos hábitos de vida direcionado para o câncer nasal e dos seios paranasais.

Abstract: This study, presented in the form of an article, is part of the Care Process in Health and Nursing research line of the Postgraduate Program in Nursing, and the Multiprofessional Research Group in Adult Health at the Universidade Federal do Paraná. Introduction: nasal and paranasal sinus cancer corresponds to less than 1% of other types of cancer, has etiological factors resulting from the environment, occupational activities and lifestyle, and a latency period varying up to 20 years for the onset of neoplastic symptoms. Objectives: to characterize the sociodemographic, clinical and occupational profile of Brazilians with sinonasal cancer; translate, culturally adapt and validate the Questionario Sulla Storia di Lavoro e Sulle Abitudini di Vita used by the Registro Tumori Seni Nasali e Paranasali from Lombardy, Italy, for the Brazilian cultural context; to examine the sociodemographic, clinical and occupational profile of patients with sinonasal cancer, and relate the occupation to exposure to leather dust,wood dust, chromium and nickel. Article 1: is an observational, descriptive, retrospective study using secondary data from the Hospital Cancer Registry Integrator from 2007 to 2019 with ICDs: C30.0 and C31.0 to C31.9. Analysis of 1,803 records was performed, highlighting that 1,161 (64%) were male, predominant age group of 50-59 years (26%; n=298), white race/color (46%; n=535) , single (55%; n=640), incomplete primary education (40%; n=461), with incidence of neoplasia in the maxillary sinus (52%; n=943), and clinical staging grade IV (32%; n=575). The occupations registered in Brazilians with sinonasal cancer were in Group 6 (64.7%; n=701) - agricultural, forestry and fishing workers, and in Group 8 (26.7%; n=289) - workers in the production of industrial goods and services, mainly in the states of Bahia (11%; n=206) and Minas Gerais (18%; n=327). Article 2: describes a methodological study with the steps of translation, synthesis, back-translation, back-translation report, review, pilot test and final translation proposed by the European Organization for Research and Treatment of Cancer. The instrument was divided into 11 domains according to characteristics of the questions in the original instrument. The pre-test was carried out between July and September 2021 in a reference hospital in oncology in the state of Paraná, Brazil, with 15 participants that were patients with nasal and paranasal sinus cancer, and five family members. The instrument obtained an index of 94% agreement among judges, who made suggestions for inclusion, semantic maintenance and replacement in 11 domains. In the pre-test, although participants confirmed their 100% (n=15) understanding of questions and domains, all had difficulty interpreting the word "popper", and 53% (n=8) made suggestions for improvements in the questionnaire. One participant requested the inclusion of hookah in smoking habits. Article 3: consists of a case series report from an oncology hospital in the state of Paraná, southern Brazil, from 2005 to 2021. Patients of both sexes aged over 18 years, with ICD C30 and group C31, under healthcare in the last 12 months at the hospital, or family members (in the case of patient's death) aged 18 years or older were included. Participants were interviewed using the Work History and Lifestyle Questionnaire. The data obtained were analyzed by simple and absolute frequency. Results: Article 3 had 52 participants that were male (56%; n= 29), married (31%; n= 16), with complete primary education (23%; n= 12) and no history of smoking (27 %; n=14), and the prevalent location was C30.0 in men (33%; n=17) with squamous cell carcinoma (40.3%; n=21). Carcinogenic exposure to wood dust (29.8%; n=17), chromium and nickel (17.5%; n=10), and leather and leather products (14%; n=8). Conclusion: the frequency of nasal and paranasal sinus cancer was higher in males with primary education, in agricultural workers and in the manufacturing industry who were exposed to the carcinogenic agent; the study may motivate reflections on the involvement of nasal and paranasal sinus cancer in the Brazilian context, mainly of occupational origin, according to monographs of the International Agency for Research on Cancer, which emphasizes the importance of using a research instrument with complex and essential information of occupational history and lifestyle habits directed to nasal and paranasal sinus cancer.

Assessments of some trace metals in water samples of nursery pond of Grass Carp (Ctenopharyngodon idella, Valenciennes, 1844) in Bannu Fish Hatchery of Khyber Pakhtunkhwa, Pakistan / Avaliações de alguns vestígios de metais em amostras de água de viveiro de carpa capim (Ctenopharyngodon idella, Valenciennes, 1844) em Bannu Fish Hatchery de Khyber Pakhtunkhwa, Paquistão

The present investigation was aimed to examine the concentrations of trace metals including e.g copper (Cu), manganese (Mn), nickel (Ni), and zinc (Zn) in water samples collected from nursery pond of grass carp (Ctenopharyngodon idella) in Bannu Hatchery of Khyber Pakhtunkhwa during the period from April 2018 to January 2019. The temperature and pH of each water sample were measured for the whole study duration. The concentration of Copper (Cu), Manganese (Mn), Nickel (Ni), and Zinc (Zn) in collected water samples were measured in mg/liter by using Atomic Absorption Spectrophotometer. The blank and standard solutions for device calibration Standard solutions i.e., 2.0 mg, 4.0 mg, and 6.0 were used to measure the concentration of these metals in water samples to verify the measurements. The data was statistically analyzed on descriptive statistics (estimation of proportions and standard deviation) used to summarize mean concentration. The results obtained of both temperature and pH of water samples were found in ranged 10 to 36 0C and 7.0 to 8.44; whereas the size of fry stages was ranged from 4.0 to 56.0 mm in total length. The results of investigated metals found in pond water samples are in order of Zn>Mn>Ni>Cu, respectively. As optimum temperature and pH for grass carp were mostly between 15 0C and 30 0C and pH 6.5 to 8.0. It was concluded from obtained results that temperature, pH, and trace metals were found appropriate for the growth of Ctenopharyngodon idella from fry to fingerling stages, but the highest amount of zinc can cause its mortality. It is a preliminary study on grass carp culturing in Bannu fish hatchery so, it would provide useful information for model fish seed production unit in a hatchery.

A presente investigação teve como objetivo examinar as concentrações de metais traço, incluindo cobre (Cu), manganês (Mn), níquel (Ni) e zinco (Zn) em amostras de água coletadas de viveiro de carpa-capim (Ctenopharyngodon idella) em Incubatório de Bannu de Khyber Pakhtunkhwa durante o período de abril de 2018 a janeiro de 2019. A temperatura e o pH de cada amostra de água foram medidos durante todo o período do estudo. A concentração de cobre (Cu), manganês (Mn), níquel (Ni) e zinco (Zn) nas amostras de água coletadas foi medida em mg / litro usando espectrofotômetro de absorção atômica. As soluções em branco e padrão para as soluções padrão de calibração do dispositivo, ou seja, 2,0 mg, 4,0 mg e 6,0, foram usadas para medir a concentração desses metais em amostras de água para verificar as medições. Os dados foram analisados estatisticamente em estatística descritiva (estimativa de proporções e desvio padrão) usada para resumir a concentração média. Os resultados obtidos tanto de temperatura quanto de pH das amostras de água variaram de 10 a 36 0C e 7,0 a 8,44, enquanto o tamanho dos estágios de alevinos variou de 4,0 a 56,0 mm no comprimento total. Os resultados dos metais investigados encontrados em amostras de água de lagoas são da ordem de Zn > Mn > Ni > Cu, respectivamente. A temperatura e o pH ótimos para a carpa-capim foram principalmente entre 15 0C e 30 0C e pH 6,5 a 8,0. Concluiu-se, a partir dos resultados obtidos, que temperatura, pH e traços de metais foram considerados adequados para o crescimento de Ctenopharyngodon idella desde os estágios de alevinos até alevinos, mas a maior quantidade de zinco pode causar sua mortalidade. É um estudo preliminar sobre a cultura da carpa-capim em incubatório de peixes Bannu, portanto forneceria informações úteis para modelo de unidade de produção de sementes de peixes em um incubatório.

Application of mixture analysis methods in association between metals mixture exposure and DNA oxidative damage / 中华预防医学杂志

Objectives: To study the association between metals mixture exposure and DNA oxidative damage using mixture analysis methods, and to explore the most significant exposure factors that cause DNA oxidative damage. Methods: Workers from steel enterprises were recruited in Shandong Province. Urinary metals were measured by using the inductively coupled plasma mass spectrometry method. The level of urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) was determined by using the ultra-high performance liquid chromatography-mass spectrometry method. Bayesian kernel machine regression (BKMR), elastic net regression and quantile g-computation regression were used to analyze the association between urinary metals and urinary 8-OHdG. Results: A total of 768 subjects aged (36.15±7.40) years old were included in the study. BKMR, elastic net regression and quantile g-computation all revealed an overall positive association between the mixture concentration and increased urinary 8-OHdG. The quantile g-computation results showed that with a 25% increase in metal mixtures, the urinary 8-OHdG level increased by 77.60%. The elastic net regression showed that with a 25% increase in exposure risk score, the urinary 8-OHdG level increased by 26%. The BKMR summarized the contribution of individual exposures to the response, and selenium, zinc, and nickel were significant contributors to the urinary 8-OHdG elevation. Conclusion: Exposure to mixed metals causes elevated levels of DNA oxidative damage, and selenium, zinc, and nickel are significant exposure factors.

Role of selenoprotein M knockdown in the melatonin antagonism of nickel-induced apoptosis and endoplasmic reticulum stress in mouse heart / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

The aim of this study was to investigate the role of selenoprotein M (SelM) in endoplasmic reticulum stress and apoptosis in nickel-exposed mouse hearts and to explore the detoxifying effects of melatonin. At 21 d after intraperitoneal injection of nickel chloride (NiCl2) and/or melatonin into male wild-type (WT) and SelM knockout (KO) C57BL/6J mice, NiCl2 was found to induce changes in the microstructure and ultrastructure of the hearts of both WT and SelM KO mice, which were caused by oxidative stress, endoplasmic reticulum stress, and apoptosis, as evidenced by decreases in malondialdehyde (MDA) content and total antioxidant capacity (T-AOC) activity. Changes in the messenger RNA (mRNA) and protein expression of genes related to endoplasmic reticulum stress (activating transcription factor 4 (ATF4), inositol-requiring protein 1 (IRE1), c-Jun N-terminal kinase (JNK), and C/EBP homologous protein (CHOP)) and apoptosis (B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), Caspase-3, Caspase-9, and Caspase-12) were also observed. Notably, the observed damage was worse in SelM KO mice. Furthermore, melatonin alleviated the heart injury caused by NiCl2 in WT mice but could not exert a good protective effect in the heart of SelM KO mice. Overall, the findings suggested that the antioxidant capacity of SelM, as well as its modulation of endoplasmic reticulum stress and apoptosis, plays important roles in nickel-induced heart injury.

Fatigue failure of NiTi endodontic files: scoping review / Falla por fatiga de limas NiTi para endodoncia: revisión exploratoria de cobertura temática

Abstract Introduction: Nickel-Titanium (NiTi) endodontic files are made of hyperelastic material with shape memory. However, these files suffer a sudden fracture during the endodontic treatment, which is considered an unfavorable prognosis. Many studies have been conducted to establish fatigue resistance focused on file brands and determine which is better. Although the most common failure mechanisms have been established for motorized endodontic files, the information is scattered, making it difficult to develop clear research trends. Methods: a scoping review was carried out using Scopus, Dimensions.ai, Web of Science, and Science Direct databases to answer screening questions related to the predominant fracture mechanism in NiTi files, test types, and equipment used for experimentation and to identify the most active authors. Results: using the general search terms, 432 research papers were found, of which 75 were finally selected after eliminating duplicates and applying exclusion criteria. Conclusions: typical failure mechanisms for rotatory and reciprocating files were identified based on the panoramic review and bibliometric indicators. Also, the standard mechanical tests for endodontic files and the characteristics of their assemblies were summarized. The most active authors in the area and their nationality were tagged. Finally, gaps for future research are proposed to generate a comprehensive knowledge of NiTi file failure.

Resumen Introducción: las limas de Níquel-Titanio (NiTi) utilizadas en endodoncia están hechas de un material hiperelástico con memoria de forma. Sin embargo, estas limas sufren fractura repentina durante el tratamiento, lo cual se considera un pronóstico desfavorable. Se han realizado diversos estudios para establecer la resistencia a la fatiga de limas, y determinar cuál marca es mejor. Aunque se han establecido los mecanismos de falla más comunes para las limas de endodoncia motorizadas, la información se encuentra dispersa, dificultando la definición de tendencias claras de investigación. Métodos: se realizó una revisión de cobertura temática utilizando las bases de datos Scopus, Dimensions.ai, Web of Science y Science Direct, para responder a preguntas orientadoras relacionadas con el mecanismo de fractura predominante en las limas NiTi, tipos de pruebas y equipos utilizados para la experimentación e identificar los autores más activos en el área. Resultados: utilizando términos generales de búsqueda, se encontraron 435 trabajos de investigación. Finalmente se seleccionaron 75, tras eliminar duplicados y aplicar criterios de exclusión. Conclusiones: a partir de la revisión panorámica de literatura y empleando algunos indicadores bibliométricos, se identificaron los mecanismos de falla más comunes para las limas rotatorias y reciprocantes. Se obtuvo información sobre ensayos mecánicos y los montajes más utilizados para las limas de endodoncia. Se identificaron los autores más activos en el área y su nacionalidad. Por último, se sugieren oportunidades de investigación para generar un conocimiento exhaustivo sobre la falla de las limas NiTi.

Evolution and development: engine-driven endodontic rotary nickel-titanium instruments / 国际口腔科学杂志·英文版

Various engine-driven NiTi endodontic files have been indispensable and efficient tools in cleaning and shaping of root canals for practitioners. In this review, we introduce the relative terms and conceptions of NiTi file, including crystal phase composition, the design of the cutting part, types of separation. This review also analysis the main improvement and evolution of different generations of engine-driven nickel-titanium instruments in the past 20 years in the geometric design, manufacturing surface treatment such as electropolishing, thermal treatment, metallurgy. And the variety of motion modes of NiTi files to improve resistance to torsional failure were also discussed. Continuous advancements by the designers, provide better balance between shaping efficiency and resistance to of NiTi systems. In clinical practice an appropriate system should be selected based on the anatomy of the root canal, instrument characteristics, and operators' experience.

Bioaccumulation of heavy metals in the tissues of Schizothorax plagiostomus at River Swat / Bioacumulação de metais pesados nos tecidos de Plagiostomo esquizotórax em River Swat

Snow trout (Schizothorax plagiostomus) is an economically important freshwater fish, mostly found in northern areas of water reservoirs of Pakistan. The current study was conducted in River Swat to analyze the bioaccumulation of heavy metals (Pb, Cr, Ni, and Zn) in tissues of Schizothorax plagiostomus. Tissues were extracted and dissolved in perchloric acid (HClO4) and nitric acid (HNO3) along with hotplate. The heavy metals, zinc (Zn), lead (Pb), chromium (Cr), and Nickel (Ni) were determined using Perkin Elmer 2380 atomic absorption spectrophotometer. Results shows great variation in the content of the metal related to tissue type and sampling sites. A high concentration of bioaccumulation was reported at Charbagh, whereas lowest at Odigram: Charbagh>Landakai>Odigram. In the same way, Cr was the most accumulated heavy metal followed by lead, nickel, and Zinc.

A truta das neves (Schizothorax plagiostomus) é um peixe de água doce economicamente importante, encontrado principalmente nas áreas ao norte de reservatórios de água do Paquistão. O presente estudo foi realizado em River Swat para analisar a bioacumulação de metais pesados (Pb, Cr, Ni e Zn) em tecidos de Schizothorax plagiostomus. Os tecidos foram extraídos e dissolvidos em ácido perclórico (HClO4) e ácido nítrico (HNO3) com placa de aquecimento. Os metais pesados zinco (Zn), chumbo (Pb), cromo (Cr) e níquel (Ni) foram determinados usando espectrofotômetro de absorção atômica Perkin Elmer 2380. Os resultados mostram grande variação no conteúdo do metal relacionado ao tipo de tecido e locais de amostragem. Uma alta concentração de bioacumulação foi relatada em Charbagh, enquanto a mais baixa, em Odigram: Charbagh > Landakai > Odigram. Da mesma forma, Cr foi o metal pesado mais acumulado, seguido por Pb, Ni e Zn.

Cyclic Fatigue Resistance and Surface Roughness of Rotary NiTi Instruments after Simulated Clinical Use in Curved Root Canals - An Atomic Force Microscopy Study

Abstract Objective: To examine the cyclic fatigue resistance and surface topography of TruNatomy and ProTaper Gold nickel-titanium rotary files and evaluate the presence of alterations to surface topography following instrumentation in simulated curved canals. Material and Methods: Twenty-four nickel-titanium instruments, twelve each of TN and PTG file systems, were evaluated for cyclic fatigue resistance. The rotary files were rotated in a simulated root canal with standardized diameter, angle of curvature, and radius of curvature in a custom-made cyclic fatigue testing device until the instrument fracture occurred. The time to fracture for each instrument was recorded with a stopwatch; in seconds in each group. Fractured instruments were subjected to atomic force microscopy analysis measuring the average roughness and the root mean square values to investigate surface features of endodontic files. Mean values and standard deviation were calculated. Data were analyzed using the Mann-Whitney U test. Results: Time to fracture was marginally higher in PTG instruments than in the TN file systems. PTG files exhibited higher surface roughness when compared with TN files (p<0.05). Conclusion: TN file system had a higher cyclic fatigue resistance than PTG. Cyclic fatigue causing file breakage did affect the surface topography of the files. PTG files showed a higher surface porosity value than the TN files (AU).

Influência do hipoclorito de sódio na resistência à fadiga cíclica em instrumentos rotatórios endodônticos de memória controlada de NiTi: uma avaliação experimental / Influence of sodium hypochlorite on cyclic fatigue resistance in niti controlled memory endodontics rotary instruments: an experimental evaluation

Introdução: É importante saber se o hipoclorito de sódio (NaOCl) influencia a resistência à fadiga cíclica das limas de níquel-titânio (NiTi). Objetivo: Avaliar a influência de NaOCl 2,5% na resistência à fadiga cíclica de dois sistemas de NiTi. Material e método: 40 instrumentos rotatórios - 20 TruNatomy® (TRU, Dentsply Sirona, Maillefer, Ballaigues, Suíça) e 20 Prodesing Logic2® (PDL2, Bassi, Belo Horizonte, Minas Gerais, Brasil) - foram aleatoriamente distribuídos em 4 grupos experimentais (n = 10) imersos em água destilada (H2O) e NaOCl 2,5% em temperatura a 37°C. Foram submetidos a testes de fadiga cíclica mensurando o número de ciclos para fratura (NCF) e análise dessas superfícies pós-teste em microscópio eletrônico por varredura. Para a análise estatística entre os grupos, foi aplicada a análise de variância (ANOVA), complementada com o pós-teste de Tukey. Resultado: Houve diferença estatística em todos os grupos (P<0.05). Os instrumentos PDL2 obtiveram maior resistência à fratura nas condições em H2O e em NaOCl 2,5% comparados aos instrumentos TRU. Na análise de grupos de instrumentos nas soluções de NaOCl e H2O, foi observado que o NaOCl 2,5% diminuiu o NCF. Conclusão: A resistência à fadiga cíclica dos instrumentos TRU e PDL2 diminuiu com NaOCl 2,5%. Os instrumentos PDL2 foram mais resistentes à fratura em relação aos instrumentos TRU.

Introduction: It is important to know whether sodium hypochlorite (NaOCl) influences the cyclic fatigue resistance of nickel-titanium (NiTi) files. Objective: To evaluate the influence of NaOCl 2.5% on the cyclic fatigue resistance of two NiTi systems. Material and method: Forty rotary instruments - 20 TruNatomy® (TRU, Dentsply Sirona, Maillefer, Ballaigues, Switzerland) and 20 Prodesign Logic2® (PDL2, Bassi, Belo Horizonte, Minas Gerais, Brazil) - were distributed randomly across four experimental groups (n=10) and submerged in distilled water (H2O) or 2.5% NaOCl at 37°C according to allocation. Cyclic fatigue testing was then performed, measuring the number of cycles to fracture (NCF), and post-test surfaces were analysed by scanning electron microscopy (SEM). Statistical Analysis: Analysis of variance (ANOVA) was applied for between-group analysis, followed by Tukey's post-hoc test. Result: A significant difference was observed in all groups (P<0.05). PDL2 instruments showed higher fracture resistance under H2O and 2.5% NaOCl conditions compared to TRU. Analysis of all instrument groups showed that exposure to 2.5% NaOCl decreased the NCF compared to H2O. Conclusion: Cyclic fatigue resistance of the TRU and PDL2 instruments was decreased by exposure to 2.5% NaOCl. PDL2 instruments were more resistant to fracture than TRU instruments.

Avaliação de risco à saúde humana associada a exposição inalatória de arsênio, níquel e chumbo no MP10 de fonte veicular, na cidade de São Paulo, SP / Assessment of human health risks associated with airborne arsenic, nickel and lead exposure in PM10 from vehicular sources in Sao Paulo city

Introdução. O material particulado (MP) emitido pela queima de combustíveis fósseis de origem veicular é a principal fonte de exposição ambiental à elementos potencialmente tóxicos (EPTs) presentes no ar atmosférico dos centros urbanos, entre eles arsênio, níquel e chumbo. Objetivos. Este estudo avaliou os riscos à saúde humana de efeitos não carcinogênicos e efeitos carcinogênicos associados a exposição inalatória de arsênio, níquel e chumbo no MP10 de origem veicular, coletado em uma das estações de monitoramento da qualidade do ar, na cidade de São Paulo, ao longo dos anos 2002, 2006, 2009 e 2012. Métodos. Os dados de concentração dos EPTs foram obtidos pela Companhia Ambiental do Estado de São Paulo (CETESB) e estão disponíveis no website da agência. As amostras semanais foram coletadas em todas as estações do ano, durante 2002, 2006, 2009 e 2012 na estação de monitoramento Cerqueira César, localizada próximo a uma via de intenso tráfego veicular. A análise estatística foi realizada utilizando o Software R (versão 4.0.5) e RStudio (versão 1.2). O software ProUCL foi usado para estimar os valores UCL95%. A avaliação de risco à saúde humana foi realizada de acordo com os métodos da United States Environmental Protection Agency (USEPA). Resultados. As concentrações de arsênio e chumbo no ar apresentaram médias mais elevadas durante o inverno do que nas outras estações (p <0,05). O chumbo apresentou o maior risco de efeitos não carcinogênicos (HQ> 1,0). Arsênio e níquel apresentaram o maior risco de efeitos carcinogênicos, inclusive acima de 1E-06. O risco para ambos os efeitos foi maior no inverno. Conclusão. Esses achados destacam a importância da poluição do ar como fator de risco para a saúde da população, principalmente em centros urbanos com intenso tráfego veicular. Ações para reduzir a exposição à poluição do ar ambiente devem ser priorizadas nas agendas de políticas ambientais e de saúde.

Background. Particulate matter (PM) emitted from the burning of fuels by vehicles is the main source of environmental exposure to potentially toxic elements (PTEs) present in atmospheric air in urban centers, between them arsenic, nickel and lead. Objective. This study evaluated the risk to human health from non-carcinogenic effects and carcinogenic effects associated with airborne arsenic, nickel and lead in PM10 exposure of the vehicular source collected at one of the air quality monitoring stations in the city of Sao Paulo over the years 2002, 2006, 2009 and 2012. Methods. The concentration data of the PTEs were obtained by the Sao Paulo State Environmental Protection Agency (CETESB) and are available on the agency's website. The statistical analysis was performed using the Software R (version 4.0.5) and RStudio (version 1.2). ProUCL software was used to estimate UCL95% values. The risk assessment for human health was carried out according to the methods of the United States Environmental Protection Agency (USEPA). Results. Airborne arsenic and lead concentrations showed higher means during the winter than in other seasons (p<0.05). Lead had the greatest risk of non-carcinogenic effects (HQ>1.0). Arsenic and nickel had the highest risk of carcinogenic effects, including above 1E-06. The risk for both effects was greatest in winter. Conclusion. These findings highlight the importance of air pollution as a risk factor for population health, especially in urban centers with high vehicular traffic. Actions to reduce air pollution exposure should be prioritized in environmental and health policies agendas.

Correção da deficiência transversal maxilar utilizando o expansor de níquel-titânio LEAF Expander® com o protocolo para expansão lenta: relato de caso clínico / Correction of maxillary transverse deficiency using the LEAF Expander® nickel-titanium expander with the protocol for slow expansion: a case report

Este trabalho teve como objetivo o relato do caso clínico de uma paciente que compareceu à Faculdade de Odontologia de Araçatuba com características de classe I de Angle e deficiência maxilar transversal, no tratamento foi utilizado o expansor de níquel-titânio LEAF Expander®, fabricado pela Leone, na Itália. Trata-se aparelho que possui inúmeras vantagens por aumentar a adesão do paciente ao tratamento já que não necessita da ativação em domicílio, facilitar o andamento clínico, tendo em vista que o tratamento é menos doloroso e mais fácil que os outros expansores, aumentar a previsibilidade do tratamento, pois as forças contidas nas molas são constantes e pré-determinadas em laboratório (450g de força). Mediante a análise de modelos, documentações fotográficas e do estudo do caso clínico, concluiu-se que o tratamento realizado utilizando o protocolo padrão de expansão lenta da maxila apresentou-se como uma ferramenta inovadora e eficiente no tratamento da deficiência maxilar transversal(AU)

This study aimed to report the clinical case of a patient who attended the Faculty of Dentistry of Araçatuba with Angle class I characteristics and transverse maxillary deficiency. Leon, Italy. It is a device that has numerous advantages for increasing patient adherence to treatment since it does not require activation at home, facilitating clinical progress, given that the treatment is less painful and easier than other expanders, increasing predictability treatment, as the forces contained in the springs are constant and predetermined in the laboratory (450g of force). Through the analysis of models, photographic documentation and the study of the clinical case, it was concluded that the treatment performed using the standard protocol of slow maxillary expansion presented itself as an innovative and efficient tool in the treatment of transverse maxillary deficiency(AU)

Avaliação da resistência à fadiga cíclica e torcional de quatro instrumentos rotatórios de NiTi com secções transversais semelhantes e diferentes tratamentos térmicos / Cyclic and torsional fatigue resistance of four rotary NiTi instruments with similar cross-sectional design and different thermal treatments

Objetivo: O objetivo do presente trabalho foi avaliar a resistência à fadiga cíclica e torcional de instrumentos rotatórios de níquel-titânio com secções transversais semelhantes e confeccionados com diferentes tipos de tratamentos térmicos: Hyflex CM (HCM 25/.06), Vortex Blue (VB 25/.06), Sequence Rotary File (SRF 25/.06) e EdgeSequel (EDF 25/.06) (n=20). Métodos: O teste de fadiga cíclica avaliou o tempo e o número de ciclos para a fratura (NCF) dos instrumentos em canal artificial com 60° de curvatura e 5mm de raio (n=10). O teste de torção avaliou o torque máximo e a deflexão angular para a fratura dos 3mm da ponta dos instrumentos (n=10). Após o teste de torção e de fadiga cíclica, os instrumentos foram avaliados em microscopia eletrônica de varredura (MEV) (n=10). Os dados foram analisados empregando-se os testes ANOVA e de Tukey, sendo selecionado um nível de significância de 5%. Resultados: HCM apresentou o maior tempo e NCF entre todos os instrumentos avaliados (p<0,05). O SRF apresentou um tempo semelhante (p>0,05) e menor NCF (p<0,05) do que o VB. Em relação ao teste torcional, o HCM apresentou menor valor de torque e maior deflexão angular entre os grupos avaliados (p<0,05). Não houve diferenças significativas entre VB, SRF e EDF em relação à deflexão angular (p>0,05). Conclusão: O HCM apresentou maior resistência à fadiga cíclica e deflexão angular. Entretanto, o VB apresentou maior resistência torcional para a fratura (AU).

Objective: The aim of this study was to evaluate the cyclic and torsional fatigue resistance of Nickel-Titanium rotary instruments with similar cross-sectional design and manufactured by different thermal treatments: Hyflex CM (HCM 25/.06) Vortex Blue (VB 25/.06), Sequence Rotary File (SRF 25/.06) and EdgeSequel (EDF 25/.06) (n=20). Material and Methods: Cyclic fatigue test evaluated the time and number of cycles to failure (NCF) in an artificial stainless steel canal with 60° and 5-mm radius of curvature (n=10). The torsional test (ISO 3630-1) evaluated he maximum torque and distortion angle to failure at 3 mm from the tip (n=10). After the torsional and cyclic fatigue test the instruments were evaluated by scanning electron microscope (SEM). Data were analyzed using one-way ANOVA and Tukey tests, and the level of significance was set at 5%. Results: The HCM presented the longest time and highest NCF to fatigue than all the groups (P<0.05). The SRF presented similar time (P>0.05) and lower NCF (P<0.05) to fatigue than VB. Regarding to the torsional test, HCM presented the lowest torque load and the highest distortion angle of all the groups (P<0.05). No significant difference was found among VB, SRF and EDF regarding the distortion angle (P>0.05). Conclusion: The HCM presented the highest cyclic fatigue resistance and distortion angle to failure. However, the VB showed higher torsional load to failure. (AU).

Effect of fluoride on mechanical properties of NiTi and CuNiTi orthodontic archwires: an in vitro study

ABSTRACT Introduction: After debonding, white spot may appear on the area below the bracket, which is the early clinical sign of carious lesion. There is increased caries risk underneath and adjacent to orthodontic bands and brackets, which call for maximum use of caries preventive procedures using various fluoride application methods. Objective: The aim of the study was to evaluate alterations in the mechanical properties (modulus of elasticity and yield strength) in loading and unloading phases for different orthodontic archwires (nickel-titanium [NiTi] and copper-nickel-titanium [CuNiTi]) when exposed routinely to fluoride prophylactic agents for a predetermined period of time. Methods: Preformed rectangular NiTi and CuNiTi wires were immersed in fluoride solution and artificial saliva (control) for 90 minutes at 37ºC. After immersion, specimens were tested using a 3-point bend test on a universal testing machine. Results: There is a significant reduction in the unloading yield strength when the NiTi and CuNiTi wires were exposed to APF gel. Conclusion: The result suggests that use of topical fluoride agents affect the mechanical properties of the wires, leading to increase in treatment duration. Fluoride prophylactic agents must be used with caution in patients undergoing orthodontic treatment. Injudicious use of these agents may cause corrosive effects on the orthodontic wire surfaces, with alteration in their mechanical properties.

RESUMO Introdução: Após a remoção dos braquetes, manchas brancas podem aparecer na área embaixo deles, as quais são o sinal clínico inicial da lesão cariosa. Existe um maior risco de cáries embaixo e ao redor das bandas e braquetes ortodônticos, o que exige a máxima utilização de procedimentos preventivos de cárie, usando diferentes métodos com aplicação de flúor. Objetivo: O objetivo do presente estudo foi avaliar alterações nas propriedades mecânicas (módulo de elasticidade e resistência ao escoamento), nas fases de carregamento e descarregamento de diferentes fios ortodônticos (níquel-titânio [NiTi] e níquel-titânio com adição de cobre [CuNiTi]), quando expostos rotineiramente a agentes profiláticos fluoretados, utilizados durante um período de tempo predeterminado. Métodos: Os fios pré-contornados retangulares de NiTi e CuNiTi foram imersos em solução fluoretada e saliva artificial (controle) durante 90 minutos a 37°C. Após a imersão, as amostras foram testadas utilizando-se um teste de flexão em três pontos, em uma máquina universal de testes. Resultados: Houve uma redução significativa na resistência ao escoamento na fase de descarregamento quando os fios de NiTi e CuNiTi foram expostos ao gel fluoretado. Conclusão: O resultado sugere que o uso tópico de agentes fluoretados afeta as propriedades mecânicas dos fios, levando a um aumento na duração do tratamento. Os agentes profiláticos fluoretados devem ser utilizados com cautela em pacientes submetidos a tratamento ortodôntico. O uso indiscriminado desses agentes pode causar efeitos corrosivos na superfície dos fios ortodônticos e consequente alteração das suas propriedades mecânicas.

Effect of Sprue Design in Nickel-Chromium Cast Crown Margin

ABSTRACT Objective: To determine the effect of sprue design on the marginal accuracy of the casting. Material and Methods: It was an experimental in-vitro study. There are forty-four crowns of single sprue group with a forty-four double sprue group that was compared in 6 different locations of the margin. The sections were inspected under a microscope at 50X magnification and took a micrograph. The radius from an actual casting edge to a possibly excellent margin was then documented as marginal discrepancy (d), in µm. The marginal discrepancy was documented for each of the six sections per casting. Thus 264 sections were measured for each group. Data were analysed using (ANOVA) for analysis of variance. For bivariate analyses, Chi-square and Student t test were used. The significance level was set at < 0.05. Results: The marginal discrepancy was greater in the single sprue group of cast crown (43.1 ± 4.74 µm) and in double sprue group of cast crown was less (25.7 ± 4.25 µm). This difference is statistically significant (p<0.05). The correlation between single sprue group of casting with a double sprue group of casting by student's t-test where determination height was 95%. Conclusion: Double sprue design produces a higher accurate margin than single sprue design in the nickel-chromium alloy cast crown.

Comparación de la precisión de la longitud de trabajo de cuatro localizadores apicales electrónicos con limas de acero inoxidable y níquel-titanio en conductos mesiovestibulares de primeras molares inferiores / Comparison of the precision of the working length of four electronic apical locators with stainless steel files and titanium nickel in mesiovestibular ducts of first lower molars

Objetivo: El propósito del estudio in vitro fue comparar la precisión de la longitud de trabajo de Root ZX mini, Proper Pixi, Woodpex III y Raypex 6 utilizando limas de acero inoxidable VDW C-Pilot n.º 15 y de níquel-titanio Maillefer n.º15. Materiales y métodos: Este estudio fue experimental in vitro. La muestra fue de treinta y cinco conductos mesiovestibulares de primeras molares inferiores, con cuatro localizadores apicales electrónicos Root ZX mini, Proper Pixi, Woodpex III y Raypex6. La longitud real se determinó con un calibrador Vernier digital y la medición electrónica se realizó utilizando limas de acero inoxidable y de níquel-titanio. Resultados: Al comparar la longitud real y longitud electrónica, no se encontró diferencias estadísticamente significativas (p < 0,05). Conclusiones: Se halló diferencias estadísticamente significativas al comparar la precisión de Root ZX mini, Proper Pixi, Woodpex III y Raypex 6 con limas de acero inoxidable; mientras que la precisión con limas de níquel-titanio no se vio afectada. (AU)

Objective: The purpose of this study was to compare the precision of the working length of Root ZX mini, Proper Pixi, Woodpex III and Raypex 6 using VDW C-Pilot No. 15 with Maillefer nickel titanium No. 15 and stainless steel files in mesiovestibular ducts of first lower molars. Materials and methods: This was an experimental in vitro study, including 35 mesiobuccal canals of lower first molars. The real length of 4 electronic apical locators, Root ZX mini, Proper Pixi, Woodpex III and Raypex6, was determined with a digital Vernier caliper, and electronic measurements were recorded using stainless steel and nickel titanium files. Results: There were no statistically significant differences between the real and the electronic lengths of the different tools studied (p <0.05). Conclusions: Statistically significant differences were obtained when comparing the precision of Root ZX mini, Proper Pixi, Woodpex III and Raypex 6 with stainless steel files, while the precision of nickel titanium files was not affected. (AU)

Evaluation of Apical Transportation by Three Rotary Systems in Extracted Teeth with Curved Canals / Evaluación de la transportación apical con tres sistemas rotatorios en dientes extraídos con conductos curvos

Abstract The aim of this study was to compare the apical transportation in extracted teeth using three different rotary nickel-titanium systems (Mtwo, Hyflex CM, and Typhoon). Sixty extracted first molars were randomly divided into three groups (n=20 in each group) with similar root canal curvatures (25-52 degrees). All root canals were prepared to size 30 using a crown-down preparation technique for each rotary system. Loss of working length and apical transportation were determined by X-ray evaluation. Comparisons between the groups were performed using one-way analysis of variance (ANOVA) or Kruskal-Wallis tests, and the post hoc analyses employed were Dunn´s or Tukey´s multiple comparison tests. No significant differences were detected between the different rotary systems in the loss of working length and apical transportation. This in vitro study showed that the use of these three rotary systems are safe and useful for instrumentation in curved canals; however, further in vivo research is essential to compare the effectiveness and safety of these systems for use in curved canals.

Resumen El objetivo del presente estudio fue comparar la transportación apical en dientes extraídos utilizando tres sistemas rotatorios de níquel-titanio (Mtwo, Hyflex CM y Typhoon). Sesenta primeros molares extraídos se dividieron aleatoriamente en tres grupos (n=20 en cada grupo) con curvaturas del conducto radicular similares (25-52 grados). Todos los conductos radiculares se prepararon usando una técnica corono apical para cada sistema rotatorio. La pérdida de la longitud de trabajo y la transportación apical se determinaron mediante evaluación radiográfica. Las comparaciones entre los grupos se realizaron utilizando análisis de varianza de una vía (ANOVA) o Kruskal-Wallis, y los análisis post hoc empleados fueron las pruebas de comparación múltiple de Dunn o Tukey. No se detectaron diferencias significativas entre los diferentes sistemas rotatorios en la pérdida de la longitud de trabajo y transportación apical. Este estudio demostró que el uso de estos tres sistemas es seguro y útil para su instrumentación en conductos curvos; sin embargo, investigación in vivo es necesaria para comparar la efectividad y seguridad de estos sistemas para su uso en conductos curvos.

Endodontic retreatment using a single instrument from four nickel-titanium systems - a micro-ct study

Abstract This study evaluated the efficiency of using a single instrument from three different rotary multi-file systems and compared them with that of a reciprocating single-file for endodontic retreatment by means of micro-CT. Sixty extracted canines were prepared using a size F2 ProTaper Universal file and obturated. After 30 days of storage at 37ºC and 100% humidity, the teeth were randomly divided into four groups (n=15) based on the type of instrument used to retreatment: ProTaper Next (PTN), ProTaper Gold (PTG), TRUShape 3D (TS), and WaveOne (WO). The canals were retreated using only the size 40 instrument from each system according to the manufacturer's recommendations for torque and speed. The time required to remove the filling material was recorded in seconds. The amount of initial and residual filling material and the quantity of dentin removed were assessed by means of micro-CT. Data were statistically analyzed (ANOVA and Kruskal-Wallis) at a 5% significance level. TS instruments required the highest (p<0.05) amount of time (mean, 384.80 ±144.92) compared with the WO (229.67±68.16) and PTG (248.67±64.22) and not so different from PTN instruments (327.67±133.3). No differences in the amount of dentin removed, initial and residual filling volume, and percentages of filling material were observed among the groups. The use of a single rotary instrument from the PTG, TS, and PTN systems was as effective as that of the single-file reciprocating WO system. However, none of the instruments was able to remove the filling materials completely.

Resumo Este estudo laboratorial avaliou por meio de micro-CT a eficiência do uso de um único instrumento de três sistemas rotatórios em retratamentos endodônticos, comparados a um instrumento único reciprocante. Sessenta caninos extraídos foram preparados usando o sistema ProTaper Universal (F2) e obturados. Após 30 dias de armazenamento a 37 ºC e 100% de umidade, os dentes foram divididos aleatoriamente em quatro grupos (n = 15), de acordo com o instrumento utilizado para remover as obturações endodônticas: ProTaper NEXT (PTN), ProTaper Gold (PTG), TRUShape 3D (TS) e WaveOne (WO). Os canais foram retratados usando apenas o instrumento tamanho 40 de cada sistema, seguindo as recomendações do fabricante para torque e velocidade. O tempo necessário para remover a obturação foi registrado em segundos. A quantidade de material remanescente e o volume de dentina removida foram avaliadas por meio de micro-CT. Análise estatística foi realizada (ANOVA e Kruskal-Wallis), com nível de significância de 5%. O tempo de trabalho no grupo TS foi significativamente maior (p<0.05) (média, 384,80 ± 144,92) comparado a WO (229,67 ± 68,16) e PTG (248,67 ± 64,22), e similar a PTN (327,67 ± 133,3). Não houve diferenças entre os grupos na quantidade de dentina removida e nas porcentagens de material obturador residual. O uso de apenas um instrumento rotatório dos sistemas PTG, TS e PTN foi tão eficaz quanto o do sistema WO reciprocante na remoção do material obturador. No entanto, nenhum dos instrumentos conseguiu remover completamente os materiais obturadores.

Evaluation of zinc-oxide nanocoating on the characteristics and antibacterial behavior of nickel-titanium alloy

ABSTRACT Objective: To investigate the effect of ZnO nanocoating on mechanical properties of NiTi orthodontic wires and antibacterial activity. Methods: 0.016 x 0.022-in NiTi orthodontic wires were coated with ZnO nanoparticles using an electrochemical deposition method with three electrodes system in 0.1M Zn(NO3)2. Mechanical properties and frictional resistance of the coated wires were investigated using an universal testing machine. Antibacterial effect of ZnO coating was also investigated. Results: A stable adhered ZnO nanocoating on NiTi wires was obtained. The coated wires have a significant antibacterial activity against S. aureus, S. pyogens and E. coli, and a reduction of frictional forces by 34%. Conclusion: ZnO nanocoating may improve the antibacterial effects of NiTi wires and reduce the frictional resistance. Coating may be implanted in orthodontic practice for faster and safer treatment.

RESUMO Objetivos: Avaliar o efeito do nanorrevestimento de óxido de zinco (ZnO) sobre as propriedades mecânicas e propriedades antibacterianas de fios ortodônticos de NiTi. Métodos: Fios 0,016" x 0,022" de NiTi foram revestidos com nanopartículas de ZnO por meio de um método de deposição eletroquímica com um sistema de três eletrodos a 0,1M Zn(NO3)2. Uma máquina universal de testes foi utilizada para avaliar as propriedades mecânicas e a resistência friccional dos fios revestidos. Além disso, também foram analisadas as propriedades antibacterianas do revestimento de ZnO. Resultados: Obteve-se uma aderência estável das nanopartículas de ZnO sobre os fios NiTi. Os fios revestidos apresentaram atividade antibacteriana significativa contra S. aureus, S. pyogens e E. coli, e apresentaram uma redução de 34% na força de atrito. Conclusão: O revestimento com nanopartículas de óxido de zinco pode melhorar as propriedades antibacterianas e reduzir a resistência friccional dos fios de NiTi. Assim, o revestimento dos fios pode ser utilizado na Ortodontia visando tratamentos mais rápidos e seguros.

Evaluación de la resistencia a la flexión de limas rotatorias Protaper Gold, 2Shape, V-Taper Fanta Gold / Evaluation of flexion resistance of Protaper Gold rotary limes, 2Shape, V-Tapert Fanta Gold

Antecedentes: Las limas rotatorias de níquel-titanio con tratamiento termomecánico se desarrollaron para permitir una mayor flexibilidad al instrumentar los conductos radiculares. Los instrumentos permitieron a los operadores tratar las curvaturas de los conductos con mayor facilidad. Los fabricantes están tratando de producir limas que funcionen de manera más eficiente y segura. Conocer las propiedades de las limas comercializadas es especialmente importante porque ayuda a elegir un sistema de lima apropiado. El objetivo de este estudio fue evaluar la flexibilidad de tres limas diferentes de níquel-titanio (NiTi) con tratamiento termomecánico en dos puntos diferentes. Materiales y métodos: Se midió la flexibilidad de tres limas NiTi con tratamiento termomecánico (ProTaper Gold, 2Shape y V-Taper Fanta Gold). Cada lima fue sujetada a 3 mm y 7 mm (n = 10/longitud/lima) y se utilizó una máquina de ensayo universal para doblarla a una fuerza máxima. Todos los datos fueron analizados estadísticamente por análisis de varianza de una vía y prueba de Tukey post hoc (p = 0,05) para determinar cualquier diferencia significativa. Resultados: Se halló diferencias estadísticamente significativas (p < 0,05). En general, V-Taper Fanta Gold fue la más rígida, ProTaper Gold mostró los mayores valores de fuerza y su deformación fue significativamente más flexible. Conclusión: Las limas ProTaper Gold mostraron una mayor flexibilidad en comparación con las otras limas estudiadas. (AU)

Background: Nickel-titanium rotary files with thermomechanical treatment were developed to allow greater flexibility when instrumenting the root canals. The instruments allowed operators to deal with duct curvatures more easily. Manufacturers are trying to produce files that work better efficiently and safely. Knowing the properties of marketed files is especially important in helping you choose an appropriate file system. The objective of this study was to evaluate the flexibility of three different nickel-titanium (NiTi) files with thermomechanical treatment at two different points along the file. Materials and methods: The flexibility of three NiTi files with thermomechanical treatment (Protaper Gold, 2Shape and V-Taper Fanta Gold) was measured. Each file was clamped at 3 mm and 7 mm (n = 10 / length / file) and a universal testing machine was used to bend the files to a maximum strength. All data were statistically analyzed by one-way analysis of variance and post-hoc Tukey test (P = 0.05) to determine any significant differences. Results: There were statistically significant differences (P <0.05). In general, V-Taper Fanta Gold was the most rigid, Protaper Gold showed the highest values of force and deformation was significantly more flexible. Conclusión: Protaper Gold files showed greater flexibility compared to the other files studied. (AU)