Comparação entre Reciproc Blue e quatro instrumentos réplicas: aspectos metalúrgicos, geometria, comportamento em torção e flexão / Comparison between Reciproc Blue and four replicalike instruments: metallurgical aspects, geometry, and behavior in torsion and flexion

A introdução da liga NiTi na endodontia proporcionou a fabricação de instrumentos com excelentes propriedades mecânicas, e uma das principais características é a possibilidade de alteração das temperaturas de transformação da liga, o qual pode possibilitar a presença de martensita em temperatura ambiente e consequentemente um efeito memória de forma. Entretanto, alguns dos sistemas comercializados atualmente possuem pouca ou nenhuma informação científica relatando suas propriedades mecânicas, características de design e métodos de fabricação. O objetivo deste trabalho foi comparar características geométricas, metalúrgicas e propriedades mecânicas (resistência à torção e flexão) de instrumentos Reciproc Blue (VDW, Munique, Alemanha), e quatro sistemas reciprocantes réplicas. Um total de 39 instrumentos de cada um dos sistemas reciprocantes, Reciproc Blue (RB), Prodesign R (PDR), V File (VF), V+ File (V+) e Univy One (UO) foram utilizados na pesquisa. O programa de Image J foi utilizado para mensuração dos diâmetros a cada milímetro da parte ativa e da área da seção transversal a 3 mm da ponta dos instrumentos. Imagens de MEV da parte ativa foram realizados para avaliar o acabamento superficial dos instrumentos. A composição atômica, fases presentes e temperaturas de transformação foram verificadas através de EDS, DRX e DSC, respectivamente. A flexibilidade foi aferida através de ensaios de dobramento até 45º conforme a especificação ISO 3630-1, e os ensaios de resistência à torção foram realizados de acordo com a especificação Nº28 ANSI/ADA. Todos os instrumentos apresentaram uma quantidade aproximadamente equiatômica de níquel e titânio. A análise qualitativa das fases cristalinas realizada através de ensaios de DRX, demonstrou a predominância de Fase R em todos os grupos, com exceção do grupo UO que apresenta uma mistura de fase R e martensita B19'. Na avaliação da área da seção, o instrumento RB obteve valores intermediários, os instrumentos PDR e V+ possuem menores valores e os instrumentos VF e UO possuem maiores valores. Observou-se grande impacto da geometria sobre as propriedades mecânicas, sendo que aqueles sistemas que apresentavam menor área que RB (PDR, V+) mostraram-se mais flexíveis e menos resistentes à torção (p<0.05), e o instrumento VF que teve maior área apresentou, como esperado, menos flexibilidade (p<0.05) e resistência torcional semelhante (p>0.05). A única exceção se deu com o sistema UO, que embora apresentasse uma maior área de seção, mostrou-se mais flexível e menos resistente à torção, provavelmente por influência da maior quantidade de martensita presente à temperatura ambiente. Nenhum dos instrumentos réplicas avaliados apresentaram características e comportamento mecânico iguais ao sistema padrão RB. Sugere-se que mais estudos devem ser realizados para a comparação do comportamento clínico destes instrumentos.

The introduction of NiTi alloy in endodontics has allowed the manufacturing of instruments with excellent mechanical properties, and one of the main characteristics is the ability to change alloy's transformation temperature, which can enable the presence of martensite at room temperature and consequently favor a shape memory effect. However, some of the currently marketed systems have limited or no scientific information regarding their mechanical properties, design characteristics, and manufacturing methods. The aim of this study was to compare the geometric characteristics, metallurgical aspects, and mechanical properties (torsional and flexural strength) of Reciproc Blue instruments (VDW, Munich, Germany) with four replica-like reciprocating systems. A total amount of 39 instruments from each reciprocating system, namely Reciproc Blue (RB), Prodesign R (PDR), V File (VF), V+ File (V+), and Univy One (UO), were used in the study. The Image J program was used to measure the diameters at every millimeter along the instruments active portion and the cross-sectional area at 3 mm from the instrument tip. SEM images of the active portion were obtained to evaluate the surface finishing of the instruments. Atomic composition, phases present, and transformation temperatures were determined through EDS, XRD, and DSC analyses, respectively. Flexibility was assessed by bending tests up to 45° according to ISO 3630-1 specifications, and torsional strength tests were performed according with ANSI/ADA Specification No. 28. All instruments exhibited an approximately equiatomic composition of nickel and titanium. Qualitative analysis of the crystalline phases using XRD tests demonstrated the predominance of the R-phase in all groups, except for the UO group, which exhibited a mixture of Rphase and B19' martensite. In terms of diameter and cross-sectional area evaluation, the RB instrument obtained intermediate values, while the PDR and V+ instruments had smaller values, and the VF and UO instruments had larger values. A significant impact of geometry on mechanical properties was observed, with systems exhibiting a smaller area than RB (PDR, V+) being more flexible and less torsion-resistant (p<0.05), and the VF instrument with a larger area showed, as expected, less flexibility (p<0.05) and similar torsional resistance (p>0.05). The only exception was the UO system, which, despite having a larger geometric configuration, exhibited greater flexibility and less torsional resistance, likely due to the higher amount of martensite present at room temperature. None of the replica-like instruments evaluated showed identical characteristics and mechanical behavior to the standard RB system. Further studies are suggested to compare the clinical performance of these instruments.

Quiste torcido de ovario fetal: reporte de un caso / Fetal ovarian cyst torsion. A case report

Resumen Los quistes ováricos fetales son los tumores abdominales más frecuentemente diagnosticados, generalmente después de las 29 semanas de gestación, cuando el eje hipotálamo hipófisis gónada ha madurado, con una incidencia de 1/2 500 nacidos vivos y de predominio unilateral. Usualmente son pequeños y se resuelven solos sin significado clínico. Se recomienda seguimiento cada dos semanas, siendo los quistes mayores de 4 cm los que presentan mayor frecuencia de complicaciones. Si las características continúan siendo de un quiste simple, se recomienda la resolución a término. Se presenta el caso de una gestante en quien en su control prenatal se encontró una tumoración abdominal consistente con el diagnóstico de quiste fetal. Tuvo seguimiento semanal de los parámetros hemodinámicos fetales y cesárea a las 37 semanas. La laparotomía exploradora y salpingooforectomía izquierda de la neonata tuvo diagnóstico posquirúrgico histopatológico de torsión de quiste ovárico.

ABSTRACT Fetal ovarian cysts are the most frequent fetal abdominal tumors. With an incidence of 1 in 2 500 live births and unilateral predominance, these cysts are generally diagnosed after 29 weeks' gestation, when the hypothalamic-pituitary-gonadal axis has reached maturity. They are usually small, self-resolving and have limited clinical impact. Follow-up every two weeks is recommended; cysts larger than 4 cm have the highest complication rates. If it consistently presents the features of a simple cyst, it is recommended to wait until term for resection. We report the case of a fetus with an abdominal tumor diagnosed as fetal cyst, which prompted weekly monitoring of fetal hemodynamic parameters and cesarean section at 37 weeks. The newborn underwent laparotomy with left salpingo-oophorectomy. Fetal ovarian cyst torsion was diagnosed by histological examination.

CT-based study of vertebral and intravertebral rotation in right thoracic adolescent idiopathic scoliosis.

PURPOSE: To define the longitudinal rotation axis around which individual vertebrae rotate, and to establish the various extra- and intravertebral rotation patterns in thoracic adolescent idiopathic scoliosis (AIS) patients, for better understanding of the 3D development of the rotational deformity. METHODS: Seventy high-resolution CT scans from an existing database of thoracic AIS patients (Cobb angle: 46°-109°) were included to determine the vertebral axial rotation, rotation radius, intravertebral axial rotation, and local mechanical torsion for each spinal level, using previously validated image processing techniques. RESULTS: For all levels, the longitudinal rotation axis, from which the vertebrae rotate away from the midline, was localized posterior to the spine. The axis became closer to the spine at the apex: apex, r = 11.5 ± 5.1 cm versus two levels above (radius = 15.8 ± 8.5 cm; p < 0.001) and beneath (radius = 14.2 ± 8.2 cm; p < 0.001). The vertebral axial rotation, intravertebral axial rotation, and local mechanical torsion of the vertebral bodies were largest at the apex (21.9° ± 7.4°, 8.7° ± 13.5° and 3.0° ± 2.5°) and decreased toward the neutral, junctional zones (p < 0.001). CONCLUSION: In AIS, the vertebrae rotate away around an axis that is localized posterior to the spine. The distance between this axis and the spine is minimal at the apex and increases gradually to the neutral zones. The vertebral axial rotation is accompanied by smaller amounts of intravertebral rotation and local mechanical torsion, which increases toward the apical region. The altered morphology and alignment are important for a better understanding of the 3D pathoanatomical development of AIS and better therapeutic planning for bracing and surgical intervention. These slides can be retrieved under Electronic Supplementary Material.

Stability of L-shaped and inverted triangle fixation assemblies in treating Pauwels type II femoral neck fracture: a comparative mechanical study.

PURPOSE: The aim of our study is to compare the mechanical resistance of two screw configurations in fixating type II Pauwels femoral neck fractures. METHODS: Fifteen synthetic models of femur bones in young adults were divided into three equal groups: intact (G1), models with fixation of a 5.0-mm failure zone created in the posterior cortex of the femoral neck using an L-shaped screw arrangement (G2, n = 5), and models with an identical failure zone fixated using an inverted triangle assembly (G3, n = 5). Model strength (axial loading) and rotational deviation of the fragments were load-tested until a 5.0-mm displacement was reached (step 1) and then until failure, here considered as 10.0 mm displacement in G2 and G3 or femoral neck fracture in G1 (step 2). RESULTS: In step 1, the mean resistance in G1 was 1593 N (standard deviation [SD] of 62 N); this value in G2 was 1261 N (SD 49 N) and in G3 was 1074 N (SD 153 N). During step 2, the value for G1 was 2247 N (SD 84 N), for G2 was 1895 N (SD 69 N), and for G3 was 1523 N (SD 280 N). G3 (the inverted triangle assembly) showed a significantly lower maximum load than the group using the L-shaped assembly (G2) and the control group (G1), which was significant using Kruskal-Wallis analysis of variance (p = 0.002). CONCLUSION: Under test conditions in synthetic bone, fixation using a L-shaped screw assembly provides greater mechanical resistance than an inverted triangle assembly.

Influência da deformação cíclica em torção na resistência à fadiga flexura dos instrumentos rotatórios de NiTi Hyflex CM, Typhoon CM e Vortex Blue / The influence of cyclic torcional straining on the flexural fatigue resistance of Hyflex CM, Typhoon CM and Vortex Blue rotary NiTi instruments

Os instrumentos rotatórios de NiTi são submetidos simultaneamente a tensões cíclicas flexurais e torcionais durante preparo de canais radiculares. As propriedades mecânicas destes instrumentos são afetadas por fatores como geometria, microestrutura, composição química da liga e tratamentos termomecânicos. Neste estudo avaliou-se a influência da deformação cíclica por torção na resistência à fadiga flexural de instrumentos Hyflex CM (HF; Coltene/ Whaladent Inc.), Typhoon CM, (TYP; Clinician´sChoice Dental Products,) e Vortex Blue (VB; Dentsply Tulsa Dental), calibre e taper 30/.06. Dez instrumentos novos de cada sistema foram ensaiados em um dispositivo de bancada para a determinação do número médio de ciclos até a fratura por fadiga (Nf), e outro grupo (n=10) foi submetido a um carregamento cíclico torcional de 20 ciclos contínuos de 0° a 180°. Após o carregamento, os instrumentos foram ensaiados até a ruptura por fadiga flexural nas mesmas condições que o controle. As superfícies longitudinais, bem como as superfícies de fratura por fadiga foram examinadas em microscópio eletrônico de varredura. Os resultados foram analisados pelo teste ANOVA (¿ = .05). Os instrumentos HF novos mostraram-se mais resistentes à fratura por fadiga (P < .05) seguidos por VB e TYP. Durante a ciclagem em torção, os instrumentos apresentaram redução no torque após o primeiro ciclo, com tendência à estabilização nos ciclos subsequentes. A maior queda nos valores médios de torque foi observada nos instrumentos TYP. Após o carregamento em torção, houve redução de 20%, 39% e 45% nos valores médios de Nf dos instrumentos HF, VB e TYP, respectivamente. Trincas longitudinais, decorrentes da ciclagem torcional não foram visualizadas em instrumentos CM (HF e TYP), apenas em VB. A superfície de fratura dos instrumentos HF mostrou maiores áreas de nucleação e crescimento lento de trincas. Os instrumentos avaliados, que envolvem tratamentos térmicos em sua fabricação, apresentaram comportamentos e possivelmente microestruturas distintas. Houve uma redução da resistência à fadiga após a deformação cíclica em todos os instrumentos avaliados

The NiTi rotary instruments undergo simultaneous flexural and torcional stresses during the root canal shaping. The mechanical properties of these instruments are influenced by many factors such as geometry, microstructure, chemical composition of the alloy and thermomechanical treatments. In this study, the influence of cyclic torsional straining on the fatigue resistance of different thermal treated instruments was assessed. Hyflex CM (HF; Coltene/ Whaladent Inc.), Typhoon CM, (TYP;Clinician´sChoice Dental Products,) e Vortex Blue (VB; Dentsply Tulsa Dental), size and taper 30/.06 were the instruments chosen, based on their geometry and specific characteristics of their manufacturing process. Ten new instruments for each system were tested in a bench test device to determine the mean value of the number of cycles to failure (Nf) of new instruments (GC, Control Group); another group (of 10instruments was submitted to 20 cycles of torsional straining between 0° and 180°. After the cyclic straining, the instruments (EG, Experimental Group) were submitted to fatigue until rupture under the same conditions of the control group. The longitudinal area and the fatigue fracture surfaces were examined by scanning electron microscopy (SEM). The results were analyzed by one-way analysis of variance ANOVA ( = .05). The new HF instruments displayed a higher resistance to fatigue (P < .05), followed by VB and TYP. During the torsional preloads, theinstruments exhibited a decrease in the torque values after the first cycle, with a tendency of stabilization in the following cycles. The lowest mean torque value was observed for the TYP instruments. After the torsional preloads, there was reduction of 20%, 39% and 45% of the mean Nf values for the instruments HF, VB and TYP, respectively. Longitudinal cracks, generated during the torsional preload were not observed in the CM instruments (HF and TYP), but were present in VB files. The instruments evaluated that involve a thermal treatment during its manufacturing, presented different mechanical behavior and possible distinct microstructure. There was a reduction in fatigue resistance after cyclic deformation in all instruments evaluated.Key words: Mechanical Torsion, Fatigue, Alloy, Instrumentation, CM instruments, Thermomechanical Treatment, Cyclic Loading