Role of the flat-designed surface in improving the cyclic fatigue resistance of endodontic NiTi rotary instruments

The aim of this study was to investigate the role of the flat-designed surface in improving the resistance to cyclic fatigue by comparing heat-treated F-One (Fanta Dental, Shanghai, China) nickel-titanium (NiTi) rotary instruments and similar prototypes, differing only by the absence of the flat side. The null hypothesis was that there were no differences between the two tested instruments in terms of cyclic fatigue lifespan. A total of 40 new NiTi instruments (20 F-One and 20 prototypes) were tested in the present study. The instruments were rotated with the same speed (500 rpm) and torque (2 N) using an endodontic motor (Elements Motor, Kerr, Orange, CA, USA) in the same stainless steel, artificial canal (90° angle of curvature and 5 mm radius). A Wilcoxon-Mann-Whitney test was performed to assess the differences in terms of time to fracture and the length of the fractured segment between the flat- and non-flat-sided instruments. Significance was set at p = 0.05. The differences in terms of time to fracture between non-flat and flat were statistically significant (p < 0.001). In addition, the differences in terms of fractured segment length were statistically significant (p = 0.034). The results of this study highlight the importance of flat-sided design in increasing the cyclic fatigue lifespan of NiTi rotary instruments

Differential Scanning Calorimetric (DSC) Study of New and Sterilized Nickel-Titanium Rotary Endodontic Instruments

Introduction: Nickel-Titanium (NiTi) files have become popular in endodontic procedures compared to traditional stainless steel hand files owing to their increased flexibility which is especially advantageous in curved canals. Due to the associated costs, endodontic instruments are frequently re-used, which requires sterilization between uses. With the application of temperature NiTi has the ability to undergo phase transformations, altering the properties of the instruments. The purpose of this study was to investigate phase transformations of four brands of NiTi rotary endodontic instruments in the as-received condition and after multiple sterilization cycles under steam sterilization, using differential scanning calorimetry. Materials and Methods: Four brands of nickel-titanium endodontic rotary files size 35, .04 taper were evaluated in this study: ProFile (Dentsply Tulsa Dental Specialties, Tulsa, OK), ProFile Vortex (Dentsply), Vortex Blue (Dentsply), and HyFlex CM (Coltène/Whaledent, Cuyahoga Falls, OH). The transformation temperatures and phase transformations of these files were determined in the as-received condition and after 1, 3, and 5 cycles of steam sterilization by differential scanning calorimetry. Measurements were analyzed using a two-way ANOVA. Results: There were significant differences between file brands in austenite finish temperature (p \u3c 0.05) but the only statistical significant differences in thermal properties when comparing files before and after 1, 3, and 5 cycles of steam sterilization were found with onset heating (p \u3c 0.05). Conclusion: Repeated cycles of steam sterilization do not appear to influence the phase transformations of NiTi endodontic instruments

La importancia de la mística en la filosofía de Plotino

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Mística, Linguagem e Silêncio na Filosofia de Plotino

Este artigo tem como objetivo destacar alguns aspectos importantes da experiência mística plotiniana, evidenciando, sobretudo, o problema da linguagem que aparece na Filosofia de Plotino como um termo limítrofe entre a necessidade de comunicar a respeito do Uno e entre a impossibilidade de fazê-lo.This article tries to highlight some important aspects of mystical experience in Plotinus, pointing out, above all, the problem of language that appears in the Plotinian Philosophy as a mediating term between the need to communicate the One and the impossibility of doing so

Ser lo que quieras: la libertad ontológica en Plotino y Gregorio de Nisa

A mediados del siglo XX, Jérome Gaïth señalaba la posible influencia de Enéadas VI 8 (39) de Plotino sobre la teoría de la voluntad divina de Gregorio de Nisa. En ese tratado, a pesar de ser consciente de la impropiedad de todo lenguaje para describir lo Uno, Plotino le atribuye los clásicos distintivos del obrar humano: voluntad, libertad, autodeterminación, aunque elevados al grado absoluto. En el presente estudio analizaremos la recepción y transformación de esta teoría en el Niseno y sus corolarios antropológicos, en los que extiende la virtualidad de la libertad humana al plano ontológico.In the mid-twentieth century, Jérome Gaïth drew attention to the possible influence of Plotinus’ Enneads VI 8 (39) on Gregory of Nyssa's theory of Divine will. In this treatise, despite being aware of the inappropriateness of all language to describe the One, Plotinus ascribes to it the classical traits of human action: will, freedom, self-determination, though raised to an absolute degree. In the present study we will analyse the reception and transformation of this theory in Nyssen and its anthropological corollaries, in which he extends the virtuality of human freedom to an ontological level.Fil: Bastitta Harriet, Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Centro de Estudios de Filosofía Medieval; Argentin

Comparison of Different Temperatures on Bending Properties of Six Niti Endodontic File Systems

Introduction: Manufacturers claim that modern NiTi files with proprietary heat treatment transform at higher temperatures, thus staying more martensite and being more resistant to cyclic fatigue and more flexible. There are some studies comparing the effect of body temperature and room temperature on cyclic fatigue of these newer NiTi files. However, there is not yet a study published for evaluating the relationship between bending properties of NiTi instruments and temperature following the ISO 3630-1 guideline. The objective of this study was to evaluate how temperature affects the bending properties of six different brands of NiTi rotary instruments with different transformation temperature ranges. Methods: Six commercially available NiTi files were selected for this experiment. The tested files included K3 40/.04 (Sybron Endo, Orange, CA), ProFile Series 29 Green Size 6 (Dentsply Tulsa Dental Specialties), K3XF 40/.04 (Sybron Endo, Orange, CA), Vortex Blue 40/.04 (Dentsply Tulsa Dental Specialties), ProFile Vortex 40/.04 (Dentsply Tulsa Dental Specialties), and HyFlex CM™ 40/.04 (Coltène/Whaledent Inc., Cuyahoga Falls, OH). The Austenite finish temperatures of the files were 9.6 ± 0.5, 17.6 ± 0.6, 24.9 ± 1.1, 35.4 ± 1.2, 45.7 ± 0.9, and 60.3 ± 3.1, respectively. The bending properties of the files were measured using a torsiometer (Sa bri Dental Enterprises, Inc. Downers Grove IL) following ISO 3630-1 guidelines. Twelve of each file type were grouped into 3 groups based on temperatures. Each temperature group had a total of 72 files. Group 1 measured the bending moment (g.cm) at 9±2°C, group 2 at 23±2°C, and group 3 at 35±2°C. The data was statistically analyzed by ANOVA and post hoc HSD (P\u3c0.05) Results: For all tested files, the bending moment of the files increased as the temperature rose from 9to 23 to 35°C. At all temperatures, HyFlex CM was significantly more flexible than other files. ProFile Vortex, K3XF, and Vortex Blue showed similar flexibility with each other. They were significantly more flexible than ProFile Series 29, which was significantly more flexible than K3. Conclusion: Testing temperature and brand of the files were significant independent variables affecting the flexibility of the files

Aspectos de la exégesis plotiniana de la tradición metafísica del platonismo

La tensión entre fidelidad a la tradición e innovación presente en el pensamiento plotiniano se manifiesta de modo patente en su propuesta metafísica. La ontología expuesta en las Enéadas, en efecto, es un claro ejemplo de la labor exegética mediante la cual Plotino toma las concepciones metafísicas platónico-pitagóricas precedentes y las sintetiza infundiendo nueva vitalidad en ideas antiguas. Para llevar a cabo su exégesis utiliza, incluso, conceptos aristotélicos que integra de un modo peculiar a su pensamiento platonizante. En el presente trabajo, pues, nos proponemos esclarecer el procedimiento interpretativo que Plotino lleva a cabo en la formulación de su doctrina de lo Uno y de la relación entre esta hipóstasis y la Inteligencia. En nuestro análisis examinamos las nociones metafísicas que nuestro filósofo toma como punto de partida y brindamos una interpretación de la transformación que opera sobre ellas para arribar al sistema que dio origen a una nueva corriente de pensamiento platónico.The tension between innovation and fidelity to tradition present in the thought of Plotinus manifests itself clearly in his metaphysical conception. The ontology put forward in the Enneads, in fact, is a fine example of the exegetical work by which our thinker takes the preceding platonic-pythagorean metaphysics and synthesizes it, bringing new vitality into ancient ideas. To accomplish his exegesis he even employs Aristotelian concepts incorporating them in a peculiar way to his Platonizing thought. In the present paper, hence, we intend to elucidate the interpretive procedure that Plotinus carries out to arrive at his conceptions of the One and of the relationship between this hypostasis and Intelligence. In our analysis, we examine the metaphysical notions that our philosopher takes as starting points and we offer an interpretation of the transformation he operates upon them to reach the system that gave birth to a new current of Platonic thought.Fil: Martino, Gabriel. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Mysticism, Language and Silence in Plotinus's Philosophy

This article tries to highlight some important aspects of mystical experience in Plotinus, pointing out, above all, the problem of language that appears in the Plotinian Philosophy as a mediating term between the need to communicate the One and the impossibility of doing so

Derveni theogony and Plotinian genealogy

La teogonía de Derveni construye un relato complejo sobre la organización del mundo y el poder divino desde el comienzo de los tiempos. El último rey divino, el dios supremo del universo, Zeus, que también es su demiurgo, devora el falo de su padre, Urano, para poder así regresar él mismo a una generación anterior a la primera, dando inicio bajo su reinado a un nuevo ciclo cósmico. Para Plotino, la castración de Urano representa la transcendencia del Uno-Bien respecto a la Inteligencia, simbolizada por Crono; y el Alma, Zeus, que escapa a la voracidad de su padre, constituye el primer dios demiurgo, cuya función es la de servir de mediador entre lo inteligible y el mundo sensibleDerveni theogony constructs a complex narrative about the organization of the world and the divine power from the beginning of time. The last divine king, the supreme god of the universe, Zeus, who is also his demiurge, devours the phallus of his father, Uranus, in order to return himself to a generation before the first, giving birth under his reign to the beginning of a new cosmic cycle. For Plotinus, the castration of Uranus represents the transcendence of the One-Good with regard to Intelligence, symbolized by Kronos; and the Soul, Zeus, who escapes from the voracity of his father, is the first demiurge god, whose function is to serve as mediator between the intelligible and the sensible worl