In vitro evaluation of the presence of apical deviation with employment of automated handpieces with continuous and alternate motion for root canal preparation

O presente trabalho avaliou, in vitro, a presença de desvio apical no preparo de canais radiculares em raízes mésio-vestibulares de molares superiores humanos utilizando-se de peças automatizadas de giro contínuo, sistema Pow R (Moyco Union Broach) e giro alternado, sistema M4 (Kerr - USA). A análise da presença de desvios apicais foi realizada por meio de radiografias obtidas na plataforma radiográfica confeccionada para o experimento. Os resultados mostraram não haver diferença estatisticamente significante quanto à avaliação da presença de desvio entre os dois sistemas. Não houve correlação entre o grau de curvatura das raízes e o grau de desvio apical, no sistema de giro contínuo. No entanto, o sistema de giro alternado apresentou diferença estatística de correlação direta e grau médio.The present study conducted an in vitro evaluation of the presence of apical deviation on the root canal preparation of the mesiobuccal roots of human maxillary molars employing automated handpieces with continuous motion, the Pow R system (Moyco Union Broach), and alternate motion, the M4 system (Kerr). Analysis of the presence of apical deviation was carried out by means of radiographs obtained on a radiographic desk fabricated for the study. The results demonstrated the lack of statistically significant differences between the two systems as to the evaluation of the presence of apical deviation. There was no correlation between the degree of curvature of the roots and the degree of apical deviation for the continuous motion system. However, there was a statistic difference for the alternate motion system, with a direct correlation of moderate degree

Wear analysis promoted in simulated canals apical third after endodontic preparation with K3 Taper .04 System

The authors analyzed the wear in apical third after K3 .04 System preparation. 12 sets of instruments were used and 12 simulated canals in transparent epoxy resin blocks with angles of curvature 20 and 40 degrees. Canals were photographed before preparation and after the utilization of instruments which prepared the apical stop: 30, 35, 40 e 45. The images were overposed in Adobe Photoshop program and the wear was measured in millimeters, in two points, 1 (A) and 5 (B) millimeters from the working length. By Variance Analysis the interaction existence was studied among these three factors: canal curvature, instrument caliber and curve location. In canals of 20 degrees, in both analyzed points, the wear mean promoted by instrument 40 and instrument 35 there was not statistically significant. In canals of 40 degrees, in location A, there was not statistically significant difference in the wear mean promoted by four different instruments. There was a deviation from the original trajectory to the outside the curve, in both analyzed points

Wear promoted in the apical third of simulated canals after instrumentation with protaper universal system

OBJECTIVE: This study evaluated the wear in the apical third of simulate canals after preparation with ProTaper Universal Rotary System. MATERIAL AND METHODS: 24 sets of instruments were used in 24 simulated canals in transparent epoxy resin blocks with degree of curvature of either 20°or 40°. The canals were photographed preoperatively and after preparation of the apical stop with ProTaper F3, F4 and F5 instruments. The initial and final images were exported to Adobe Photoshop® software and superimposed to detect the root canal wall differences (in mm) between them, in two points located 1 (A) and 5 (B) mm from the point where the working length was established. Data were subjected to analysis of variance to verify the existence of interaction among the factors: canal curvature, instrument size and curve location. Significant level was set at 5%. RESULTS: Regardless of the location and the canal curvature, F4 and F5 instruments produced the greatest wear (

Fabrication of biocompatible free-standing nanopatterned films for primary neuronal cultures

Devising and constructing biocompatible devices for nervous system regeneration is an extremely challenging task. Besides tackling the issue of biocompatibility, biomaterials for neuroscience applications should mimic the complex environment of the extracellular matrix, which in vivo provides neurons with a series of cues and signals to guide cells towards their appropriate targets. In this work, a novel nanopatterned biocompatible poly-ε-caprolactone (PCL) film is realized to assist the attachment and growth of primary hippocampal neurons. Costly and time-consuming processes can be avoided using plasma-surface nanotexturing obtained by a mixed gas SF6/Ar at -5 °C. The intrinsic composition and line topography of nanopatterned PCL ensure healthy development of the neuronal network, as shown by confocal microscopy, by analysing the expression of a range of neuronal markers typical of mature cultures, as well as by scanning electron microscopy. In addition, we show that surface nanopatterning improves differentiation of neurons compared to flat PCL films, while no neural growth was observed on either flat or nanopatterned substrates in the absence of a poly-d-lysine coating. Thus, we successfully optimized a nanofabrication protocol to obtain nanostructured PCL layers endowed with several mechanical and structural characteristics that make them a promising, versatile tool for future tissue engineering studies aimed at neural tissue regeneration

Deslocamento apical produzido por instrumentos de níquel-titânio acionados a motor e limas de aço inoxidável

The aim of this study was to evaluate the apical displacement produced by different rotary nickel-titanium instruments, testing the hypothesis that rotary systems with nickel-titanium instruments produce lower mean values of apical displacement than stainless steel hand instruments. A total of 100 maxillary permanent first molars were selected for the study. The mesiobuccal roots were sectioned at the top cervical third and embedded in blocks of self-curing resin. The specimens were randomly divided into 5 groups and the root canals were prepared using the following nickel-titanium instruments: Group 1 - Quantec system 2000 (Analytic Endodontics, Mexico); Group 2 - Pro-File T.0.04 (Dentsply/Maillefer, Switzerland); Group 3 - Pro-File Series 29 T.0.04 (Dentsply Tulsa, Switzerland); Group 4 - Pow-R T.0.02 (Moyco-Union Broach, USA). Specimens in Group 5 were prepared using stainless steel hand instruments Flexofile (Dentsply/Maillefer, Switzerland). All root canals were previously submitted to cervical preparation using Orifice Shaper instruments #1, 2, 3 and 4 (Dentsply/Maillefer, Switzerland). After odontometry, the remaining root canal was shaped employing increasingly larger instruments, so that the final instrument corresponded to Quantec #9, Pro-File Series 29 #6, and #35 for the other groups. Specimens in Groups 1 to 4 were prepared using an electric handpiece with 16:1 reduction at 350 rpm. The specimens in Group 5 were manually prepared. Apical displacement was measured and recorded by means of radiographic superimposition on a specific desk. Statistical analysis (ANOVA) of the results revealed that all groups presented apical displacements. Considering only the nickel-titanium instruments, Group 4 showed the lowest mean value while Groups 2 and 3 produced the highest mean apical displacement values (pO objetivo deste trabalho foi avaliar o deslocamento apical produzido por diferentes instrumentos de níquel-titânio acionadas a motor testando a hipótese de que os sistemas rotatórios que usam instrumentos de níquel-titânio produzem valores médios de deslocamento apical menores que as limas manuais de aço inox. Foram utilizados 100 primeiros molares permanentes superiores, cujas raízes mesiovestibulares foram separadas e incluídas em blocos de resina autopolimerizável. Os corpos de prova foram divididos aleatoriamente em 5 grupos e os canais radiculares preparados com instrumentos de níquel-titânio: Grupo 1 - sistema Quantec 2000 (Analytic Endodontics, México); Grupo 2 - Pro-File T.0.04 (Dentsply/Maillefer, Suíça); Grupo 3 - Pro-File Série 29 T.0.04 (Dentsply Tulsa, Suíça); Grupo 4 - Pow-R T.0.02 (Moyco-Union Broach, EUA); e Grupo 5 (limas manuais) - limas manuais de aço inox Flexofile (Dentsply/Maillefer, Suíça). Todos os canais mesiovestibulares foram submetidos a um preparo cervical prévio utilizando-se instrumentos Orifice Shaper números 1, 2, 3 e 4 (Dentsply/Maillefer, Suíça). Realizada a odontometria, o restante do canal radicular foi modelado a partir dos instrumentos do menor para o maior calibre de tal ordem que o instrumento final de preparo correspondeu ao número 9 para o Quantec, número 06 para o Pro-File Série 29 e o número 35 para os demais grupos. Nos grupos de 1 a 4 foi utilizado motor elétrico com contra-ângulo de redução de 16:1 numa velocidade de 350 rpm. No grupo 5 o preparo foi realizado manualmente. A análise dos resultados (ANOVA), obtidos pela sobreposição radiográfica numa plataforma especifica, demonstraram que todos os grupos apresentaram deslocamentos apicais, sendo que o menor valor médio foi verificado no grupo 4 e os maiores valores médios foram observados nos grupos 2 e 3 (

Dentistry Specialties Center: A qualitative evaluation in the perspective of the participant students

This study aimed to evaluate of qualitative form the expectation and the training that the CEO has proportionate to the student of graduation in Dentistry of the ULBRA. For this, a questionnaire with six open questions to the academics was carried out to students who were registered in this curricular discipline. Of the 43 enrolled students 29 (67%) had answered the questions. By means of the analysis of the gotten answers it can be observed that this curricular period of training was very important for the development critic and professional of the participant students

Análise Comparativa In Vitro do Desgaste Promovido nos Terços Cervical e Medio dos Canais Radiculares Mésio-vestibulares de Molares Superiores pelo Sistema K3 e Limas Manuais Associadas a Brocas Gates Glidden

Root canal instrumentation is one of the most important part in endodontic practice. The purpose of this study was to make an analysis of dental thickness in mesial and distal surfaces of maxillary mesiobuccal molar root canals after instrumentation with Gates Glidden drills and stainless steel hand files versus nickel titanium K3 rotary files. Twenty roots were cross-sectioned at 1mm apically to the canal root canal orifice and 1mm coronally to the curvature. Ten root canals had a coronal flaring with Gates Glidden 1 and Gates Glidden 2 and instrumentation with stainless steel hand files. Another ten roots, were shaped using K3 rotary files. The dental thickness was measured before and after the instrumentation in a stereomicroscope. The results were analysed by Student t Test (pA instrumentação dos canais radiculares é uma das etapas mais importantes da terapia endodôntica. Este estudo realizou uma análise comparativa do desgaste promovido nas paredes mesial e distal do canal mésio-vestibular de molares superiores, terços cervical e médio, pela associação das brocas Gates Glidden (Dentsply Maillefer, Ballaigues, Switzerland)) com limas manuais e pelo sistema automatizado K3 (SybronEndo, CA, USA). A amostra consistiu em vinte raízes que foram, primeiramente, incluídas em uma modificação da mufla proposta por Bramante et al (1987). Após a inclusão, as mesmas foram seccionadas transversalmente em duas superfícies de observação, 1 mm além do orifício de entrada do canal e 1mm aquém do início dacurvatura. O preparo cervical de dez raízes foi realizado com as brocas Gates Glidden números 1 e 2, sendo a instrumentação concluída com limas manuais. As outras dez raízes tiveram seus condutos preparados pelo sistema K3. As espessuras de dentina das paredes analisadas foram medidas antes e após os preparos através do uso de um microscópio metalográfico (Union), com ocular graduada, no aumento de 50x. Os resultados demonstraram valores médios de desgaste nas paredes analisadas maiores nos preparos realizados com a associação das brocas Gates Glidden e limas manuais. Somente na parede distal 1mm da entrada do canal o sistema K3 apresentou o valor médio pouco superior. Os dados foram submetidos ao Teste t de Student para amostras não pareadas, não apresentando diferenças estatisticamente significantes. Concluiu-se através deste trabalho, que as técnicas de preparo apresentam um desempenho semelhante quanto ao desgaste radicular dos terços cervical e médio

Modeling the remnants of core-collapse supernovae from luminous blue variable stars

Context. Luminous blue variable stars (LBVs) are massive evolved stars that suffer sporadic and violent mass-loss events. They have been proposed as the progenitors of some core-collapse supernovae (SNe), but this idea is still debated because of a lack of strong evidence. As supernova remnants (SNRs) can carry in their morphology the fingerprints of the progenitor stars as well as of the inhomogeneous circumstellar medium (CSM) sculpted by the progenitors, the study of SNRs from LBVs could help to place core-collapse SNe in context with the evolution of massive stars. Aims. We investigate the physical, chemical, and morphological properties of the remnants of SNe originating from LBVs in order to search for signatures in the ejecta distribution and morphology of the remnants that could reveal the nature of the progenitors. Methods. As a template of LBVs, we considered the LBV candidate Gal 026.47+0.02. We selected a grid of models that describe the evolution of a massive star with properties consistent with those of Gal 026.47+0.02 and its final fate as a core-collapse SN. We developed a three-dimensional hydrodynamic model that follows the post-explosion evolution of the ejecta from the breakout of the shock wave at the stellar surface to the interaction of the SNR with a CSM characterized by two dense nested toroidal shells, parametrized in agreement with multi-wavelength observations of Gal 026.47+0.02. Results. Our models show a strong interaction of the blast wave with the CSM which determines an important slowdown of the expansion of the ejecta in the equatorial plane where the two shells lay, determining a high degree of asymmetry in the remnant. After ≈10 000 yr of evolution, the ejecta show an elongated shape forming a broad jet-like structure caused by the interaction with the shells and oriented along the axis of the toroidal shells. Models with high explosion energy show Fe-rich internal ejecta distributions surrounded by an elongated Si-rich structure with a more diffuse O-rich ejecta all around. Models with low explosion energy instead show a more homogeneous distribution of chemical elements with a very low presence of Fe-group elements. Conclusions. The geometry and density distribution of the CSM where a LBV star goes SN are fundamental in determining the properties of the resulting SNR. For all the LBV-like progenitors explored here, we found that the remnants show a common morphology, namely elongated ejecta with an internal jet-like structure, which reflects the inhomogeneous and dense pre-SN CSM surrounding the star