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)

ASSESSMENT OF TORSION RESISTANCE OF GLIDE PATH ROTARY INSTRUMENTS

NiTi endodontic instruments for glide path are the most susceptible to fractures inside the root canal, mainly as a result of high torsional stress. Objective: The present study investigated the resistance to torsion and angular deflection of instruments destined for the glide path: ProGlider #16.02; T-File #17.02 and the MK Life #16.02. Materials and methods: Thirty rotating NiTi glide path instruments (n=10) with 25mm lengths were selected. The torsion test was performed based on ISO 3630-01 (1992). Three millimeters from the tip of the instruments, it was attached to a small load cell by a lever arm connected to the torsion shaft. Torsional strength and angular deflection were evaluated. Fracture surfaces were examined by scanning electron microscopy with magnifications of 1000x and 5000x in the cross section, and 50x in the lateral section. Statistical analysis was performed using the Kruskal-Wallis H test, followed by the Down's post hoc test. Results: The ProGlider instrument showed greater torsional strength (p<0.05) compared to the T-File (p<0.05) and MK Life (p<0.05), respectively. However, the T-File showed greater angular deflection (p<0.05) than the other groups tested. Conclusion: It can be concluded that the ProGlider instrument presented greater torque for the fracture, while the T-File instrument presented greater angular deflection.

CYCLIC AND TORSIONAL FATIGUE RESISTANCE OF THREE DIFFERENT THERMALLY TREATED NICKEL-TITANIUM ROTARY INSTRUMENTS

Background: The aim of this study was to evaluate the cyclic fatigue and torsional fatigue resistance of three thermally treated rotary instruments, such as: Logic 2 25.05 (LOG 25.05), Edge Taper Platinum 25.06 (EDT 25.06) and ProTaper Gold 25.08 (PTG 25.08).Methods: A total of 60 rotary instruments of LOG 25.05, EDT 25.06 and PTG 25.08 were used (n=20). Cyclic fatigue tests were performed at 36°C using an artificial stainless steel canal with a 60ºangle and a 5-mm radius of curvature. The time (in seconds) and number of cycles to fracture (NCF) was recorded. The torsional test evaluated the torque and angle of rotation to failure at 3 mm from the tip according to ISO 3630-1. The fractured surface of each fragment was observed by using scanning electron microscopy (SEM). Data were analyzed using one-way ANOVA and Holm-Sidak's tests for multiple comparison, the level of significance was set at 5%.Results: EDT 25.06 had highest cyclic fatigue resistance (time and NFC), followed by LOG 25.05 and PTG 25.08 (P<0.05). There were no significantly difference between LOG 25.05 and ETP 25.06 regarding the NCF (P>0.05). In relation the torsional test, the LOG 25.05 and ETP 25.06 presented similar torque (P>0.05). The PTG presented greater torque than the other groups (P<0.05). The PTG 25.08 presented the lowest angular rotation to fracture than the other groups (P<0.05). The SEM images demonstrated typical features of cyclic and torsional fracture.Conclusion: In conclusion, the LOG 25.05 and ETP 25.06 presented similar cyclic and torsional properties. The PTG 25.08 showed greater torsional strength.

Efeito da sequência de processamento durante a fabricação de instrumentos endodônticos Niti em suas propriedades mecânicas / Effect of the processing sequence during the manufacture of niti endodontic instruments on their mechanical properties

As características geométricas e técnicas de fabricação das limas endodônticas afetam o desempenho clínico e sua resistência à fratura, flexibilidade e outras propriedades. Um parâmetro muito explorado na Endodontia é a utilização de tratamentos térmicos, que promovem um aumento na resistência à fadiga e flexibilidade destes materiais. Neste estudo pretendeu-se avaliar o efeito de diferentes processos de tratamento térmico/usinagem nas propriedades físicas, flexibilidade, resistência torcional e à fadiga flexural dos instrumentos Prodesign Logic (PDL), verificando se a sequência de processamento dos instrumentos levaria a comportamentos mecânicos diferentes. Este sistema é fabricado a partir de um método inovador que envolve a realização do tratamento térmico para obtenção de memória de forma no fio NiTi anteriormente à usinagem. A hipótese nula a ser testada é que o momento de aplicação dos procedimentos de tratamento térmico e usinagem não afetariam as propriedades físicas e mecânicas de instrumentos endodônticos de NiTi. Para grupos de comparação, foram utilizados protótipos de instrumentos com as mesmas características geométricas e dimensionais, sendo um grupo de instrumentos sem tratamento térmico aplicado (SEP) e outro com o tratamento térmico realizado de forma convencional, após a usinagem do instrumento (HTP). Foram realizadas caracterização física e microestrutural com ensaios de calorimetria exploratória diferencial (DSC) e testes de difratometria de Raios-X (DRX), além de ensaios mecânicos divididos em testes de torção, dobramento em 45 e resistência à fadiga flexural. Os resultados mostraram que macroscopicamente não houve nenhuma alteração importante nas características dos três grupos de instrumentos, exceto mudanças de cor devido a diferentes sequências de processamento. Os resultados de DSC mostraram que à temperatura ambiente a liga é principalmente austenítica no grupo SEP e que após o tratamento térmico realizado nos grupos PDL e HTP, houve uma mudança nas temperaturas de transformação, com um aumento da temperatura de Af e predominância da liga NiTi em fase R. Os resultados de XDR confirmaram os achados do DSC. As diferenças nos parâmetros medidos entre diferentes tipos de instrumentos nos ensaios de resistência torcional, dobramento a 45º e fadiga flexural foi sempre considerada com um nível de significância de 95%. Os resultados para os ensaios de flexão mostraram que o grupo HTP mostrou-se o mais flexível, com os mais baixos valores de momento de dobramento, seguido por PDL e SEP. Nos resultados dos ensaios de torção foi possível observar que SEP apresentou valores mais altos de torque seguido por PDL e HTP (p<.05). Os ensaios de resistência à fadiga mostraram valores médios de NCF maiores para HTP, seguido por PDL e SEP. Entretanto, um pior comportamento do PDL só seria evidenciado clinicamente se os instrumentos fossem usados um número de vezes maior do que o recomendado pelo fabricante. Pode-se concluir que alterar o processo de fabricação dos instrumentos endodônticos, invertendo-se as etapas de usinagem e tratamento térmico, levou, de fato, a uma mudança no comportamento mecânico de instrumentos Prodesign Logic em relação aos prótótipos.

The geometric characteristics and manufacturing techniques of endodontic instruments affect clinical performance, fracture resistance, flexibility and other properties. A parameter widely explored in Endodontics is the use of heat treatments, which promote an increase in the resistance to fatigue and flexibility of these materials. This study aimed to evaluate the effect of different heat treatment / machining processes on the physical properties, flexibility, torsional strength and flexural fatigue of Prodesign Logic (PDL) instruments, verifying whether the processing sequence of the instruments would lead to different mechanical behaviors. This system is manufactured using an innovative method that involves performing thermal treatment to obtain shape memory in the NiTi wire prior to machining. The null hypothesis to be tested is that the moment of application of the heat treatment and machining procedures would not affect the physical and mechanical properties of NiTi endodontic instruments. For comparison groups, instrument prototypes with the same geometric and dimensional characteristics were used, being one group of instruments without thermal treatment applied (SEP) and another with thermal treatment carried out in a conventional manner, after machining the instrument (HTP). Physical and microstructural characterization were performed with differential scanning calorimetry (DSC) tests and X-ray diffractometry (XRD) tests, in addition to mechanical tests divided into torsion tests, 45° bending and resistance to flexural fatigue. The results showed that macroscopically there were no major change in the characteristics of the three groups of instruments, except for color changes due to different processing sequences. The DSC results showed that at room temperature the alloy is mainly austenitic in the SEP group and that after the heat treatment carried out in the PDL and HTP groups, there was a change in the transformation temperatures, with an increase in the Af temperature and predominance of the NiTi alloy in phase R. The XRD results confirmed the DSC findings. Differences in the parameters measured between different types of instruments in the tests of torsional resistance, bending at 45º and flexural fatigue were always considered with a significance level of 95%. The results for the flexibility tests showed that the HTP group proved to be the most flexible, with the lowest values, followed by PDL and SEP. In the results of the torsion tests it was possible to observe that SEP presented higher values of torque followed by PDL and HTP (p <.05). Fatigue resistance tests showed higher mean NCF values for HTP, followed by PDL and SEP. However, a worse behavior of the PDL would only be evidenced clinically if the instruments were used several times greater than that recommended by the manufacturer. It can be concluded that changing the manufacturing process of endodontic instruments, inverting the machining and heat treatment steps, led, in fact, to a change in the mechanical behavior of Prodesign Logic instruments in relation to the prototypes.

Sistema rotatorio protaper: un modelo educativo en la enseñanza de grado / Protaper rotary system: an educational model in predoctoral teaching

Objetivos: El objetivo del presente trabajo fue analizar el nivel de eventos (estiramiento/fractura) en el instumental rotatorio endodonticode niquel- titanio después del uso en Practicas Preclínicas de Grado en dientes ex vivos y tacos de acrílico Materiales y métodos: Seseleccionaron alumnos de grado de la materia Endodoncia de cuatro comisiones (n= 60) que en las pruebas de apropiación deconocimientos y destrezas, superaron el valor de 7/10. A cada alumno se le entregó un kit de ProTaper Universal, nuevo para larealización de dos prácticas: 1° en tacos de acrílicos simuladores de piezas dentarias y 2° en una pieza unirradicular extraída de bajacomplejidad. Se evaluaron las series de limas S1, S2, F1, F2 y F3 en cada población. Se realizó una lectura macro de cada instrumentocon lupa 4X, efectuada por un operador entrenado. Previamente, se realizó en el unaevaluación de los instrumentos sin uso y luego de los estirados o fracturados. Para el análisis de eventos producidos en cada serie de limas seutilizó el Test de Chi cuadrado de homogeneidad con niveles de significación de p= 0,05 (sofware estadístico Infostat) Resultados: No seencontraron diferencias significativas entre las distribuciones de los eventos en dientes y en taco. (Test de Chi2 p=0.0957). En el primeruso, de un total de 300 instrumentos utilizados, 6 sufrieron un evento, siendo en el segundo uso de 270, 12 sufrieron un evento. Para cadainstrumento, las diferencias no resultaron estadísticamente significativas (p valor de Irwin Fisher) S1 p=0.29, S2 p=0.10, F1 p=0.33,F2 p=0.81, F3 p=0.81. Observamos la frecuencia de eventos por instrumento, surgiendo que son más frecuentes los eventos con F1 y F2que con los restantes instrumentos...

Objective: The aim of this study was to analyze the behavior (events: stretching/fracture) of Ni-Ti rotatory Endodontic instruments afterthe utilization in preclinical practice, either ex vivo teeth or acrilic dowels. Materials and methods: undergraduate Endodontic studentsbelonging to four different courses with higher califications (more than 7/10) have been selected (n = 60). Each student has been deliveredwith a brand new ProTaper Universal Kit with the purpose of carrying out two endodontic practices, 1° in acrilics dowels, simulating ateeth and, 2° in a natural low complexity single rooted teeth. The series of files S1, S2, F1, F2 y F3 were assessed in each population. Amacro observation with a 4x magnified lens was performed by a qualified operator. Previously, a MEB observation had been performed onthe brand new instruments and in the post-use stretched or fractured instruments. The Chi square test of homogenity with significancelevels of p = 0.05 have been utilized for the analysis of the events (Infostat Estatistical Software). Results: No significant differences hasbeen found between the event distributions (Teeth/Acrilics dowels) (Test Chi2 p = 0,0957). A total of 300 files used for first time, 6suffered some kind of event, while in the second, a total of 270 files, 12 suffered some kind of event (stretching/fracture). The differenceswere not statistically significant on each file (p = Irwin Fisher value) S1 p=0.29, S2 p=0.10, F1 p=0.33, F2 p=0.81, F3 p=0.81.The event for each instrument has been detected to be more frequent with files F1 and F2 than with other files...

Information regarding use of rotary nickel- titanium endodontic instruments among general dental practitioners: a questionnaire survey

Aim: A cross-sectional questionnaire survey was conducted to obtain information on the use of rotary nickel ­titanium endodontic instruments was conducted among General Dental Practioner A two sectioned questionnaire was mailed to 200 randomly general practioners to obtain information on usage of Nickel ­Titanium endodontic instrument and data was collected. Results: Forty-six percent of the general practioners had used rotary NiTi instruments. 76% dentists use NiTi files for five or more times a week. Most of the dentist used NiTi file coronally &apically. General dentists experienced more file fracture at size 20 and 25 with 0.02 and 0.04 taper. Conclusions: Dentists are familiar with limitations of NiTi instruments and techniques. Current study showed the awareness of dentists about benefits of NiTi rotary instruments application comparing to traditional techniques and also the high percent usage of these instruments among general dentists.

Influência de diferentes instrumentos de exploração no comportamento em torção dos instrumentos MTWO após uso clínico múltiplo / influence of Nickel-Titanium rotary glide path on the torsional resistance of Mtwo shaping instruments after multiple clinical use

As propriedades mecânicas, especialmente a resistência dos instrumentos endodônticos de NiTi são influênciadas pelas suas características geométricas, físicas e químicas, somadas ainda à influência da anatomia dos canais radiculares. A exploração e negociação do canal radicular seguido de dilatação prévia ao processo de formatação (Glide Path) reduz consideravelmente as chances de fratura dos instrumentos. Essa manobra elimina as interferências em toda a extensão do canal, possibilitando aos instrumentos seguintes agirem livremente na formação e limpeza minimizando assim, a sobrecarga sobre o mesmo. O objetivo desse trabalho foi avaliar a resitência torcional após uso clínico múltiplo dos instrumentos de Niti PathFile e Scout RaCe e a influência de três diferentes sequências de glide path (K-File, PathFile e Scout RaCe) no comportamento em torção dos instrumentos de formatação MtWo...

The mechanical properties, mainly the resistance of endodontic instruments are affected by factors such as diameter, design, chemical composition, physical properties and canal anatomy. Instrument failure can be controlled by creating a manual or mechanical glide path. The aim of this study was to evaluate the torsional resistance of PathFile and Scout RaCe NiTi rotary instruments with the purpose of "glide path” after multiple clinical use and the influence of three different preflaring (K-File, PathFile and Scout RaCe) on the torsional resistance of shaping Mtwo files after multiple clinical use. The mechanical behavior was evaluated by torsion tests, in accordance with specification ISO 3630-1. All instruments showed geometric features within the tolerance limits and no significant difference concerned about the torsional resistance. Despite of one subtle increase in torsional resistance is noted, it is suggested as an effect of simultaneous sterilization methods or by the work hardening of the NiTi alloy. The present study highlights the importance of preparing the glide path before introducing the shaping files and concludes if sterilization does not render rotary NiTi endodontic instruments stronger, it does not result in deleterious effects that could reducetheir mechanical resistance.

Application of cotton rolls as protective sleeves of endodontic files / 实用口腔医学杂志

The effects of cotton roll and the traditional gauze wrapper in the protection of endodontic files were observed.Cotton roll showed firm protection and feasible operation advantages,it was more effective than gauze wrapper in the protection of endodontic files(P<0.01).

Theoretical evaluation of nickel-titanium MTWO series rotary files

Las limas rotatorias de níquel-titanio son un avance tecnológico que permite al odontólogo llevar a cabo tratamientos en conductos con morfologías irregulares Lamentablemente, estos instrumentos pueden fracturarse sin presentar señales visibles que permitan prevenir este accidente. Por lo tantoel objetivo del presente estudio fue evaluar teóricamente el comportamientomecánico de las limas rotatorias de Níquel-Titanio para uso en endodoncia Mtwo® para determinar cuál de losinstrumentos de la serie básica es el que presenta mayor probabilidad de fractura. Con este fin se realizó un análisis por medio del método de los elementos finitos utilizando modelos matemáticos de los instrumentos de la serie básica de las limas Mtwo®. Aestos instrumentos se les aplicaron cargas de flexión y torsión en condiciones normales y en condiciones extremas, para determinar cuáles presentaban los esfuerzos de Von Mises más altos. En una aproximación similar al uso normal, ninguno de los modelosde las limas alcanzó el limite máximo de falla por fractura. Ante un uso inadecuado, los modelos de las limas 10/0.04 y 25/0.06 mostraron los esfuerzos de Von Mises más altos tanto a flexión como a torsión respectivamente, por lo tanto se recomienda dar un solo uso a la lima 10/0.04 y a la lima 25/0.06 de Mtwo® para prevenir la fractura de estos instrumentos.

Nickel-Titanium rotary files are a technological development thatenables dentists to prepare irregularly shaped root canals withoutaltering them. Unfortunately, these files may fracture without anyprior visible warning signs. The aim of this study was to perform atheoretical evaluation of the mechanical behaviour of Mtwo®Nick-el-Titanium rotary files for endodontics, in order to determinewhich of the files in the basic series are most likely to fracture.Mathematical models of the Mtwo®basic file series were analyzedusing the finite elements method. Bending and torsion loads wereapplied to the files both under normal conditions and under extremeconditions, to determine which of them had the highest Von Misesstresses. When the approximation was similar to normal use, noneof the file models reached the maximum limit of failure by fracture.When used inadequately, file models 10/0.04 and 25/0.06 had thehighest Von Mises stresses for bending and torsion, respectively.Thus, it is recommended that Mtwo®files10/0.04 and 25/0.06should be used once only, to prevent fractures.

Apical and cervical displacement produced by hand and engine-driven stainless steel and nickel-titanium instruments in simulated curved root canal

The purpose of this study was evaluate the occurrence of displacement on the apical and cervical thirds of artificial curved root canals with 30° of curvature, comparing the use of stainless steel hand and oscillatory files with nickel-titanium (NI-TI) hand, rotary and oscillatory files. Methods: Seventy artificial curved root canals were divided into 7 groups (n=10). All canals were prepared with sizes 15to 40 instruments at the working length according to a crown-down technique. The amount of material removed in the curved portion of the simulated canals at2 mm level outside and 11 mm inside was measured. Data were analyzed statistically by ANOVA and Tukey’s test (p<0.05). Results: There was statistically significant differences (p<0.05) at 2 mm level between NI-TI and steel stainless groups. At 11 mm, statistically significant differences (p<0.05) were observed between the groups that used rotary systems (5 and 6) and the remaining groups. Conclusions: The most centered preparations were those belonging to groups 5 and 6, at both levels. Root canal preparation with NI-TI files yielded better results than the stainless steel files especially when mechanically activated.

Resistência à fadiga flexural de instrumentos rotatórios de níquel-titânio de diferentes características geométricas antes e após o uso / Flexural fatigue resistance of nickel-titanium rotary instruments of different geometric characteristics before and after use

Este estudo avaliou a resistência à fadiga flexural de instrumentos rotatórios de níquel-titânio de diferentes características geométricas, antes e após o uso em canais artificiais. Foram selecionados instrumentos rotatórios dos sistemas Race (FKG Dentaire) e K3 (SybronEndo) com diâmetro de ponta de 0,25 mm, conicidade 0,04 e 25 mm de comprimento. Os instrumentos foram divididos em quatro grupos (n = 12 cada grupo), totalizando 48 instrumentos, como segue: Grupo Controle 01 (GC 01), instrumentos Race sem uso; Grupo Controle 02 (GC 02), instrumentos K3 sem uso; Grupo Experimental 01 (GE 01), instrumentos Race de cinco usos, e Grupo Experimental 02 (GE 02), instrumentos K3 de cinco usos. A simulação de uso foi realizada em canais artificiais de resina, com ângulo de curvatura de 40° e raio de 5 mm, utilizando-se um motor elétrico com velocidade de 350 rpm e torque de 1 N.cm-1.Todos os grupos foram submetidos a ensaios de fadiga flexural em um dispositivo que permitia ao instrumento girar livremente, reproduzindo a instrumentação rotatória em canal curvo. O tempo despendido até a fratura foi aferido por um cronômetro. O teste ANOVA mostrou diferença estatisticamente significante entre as amostras (p < 0,05). O uso e a característica geométrica dos instrumentos influenciam na sua resistência à fadiga flexural (p < 0,05). Os instrumentos do GC 01 (K3 sem uso) apresentaram maior resistência à fadiga, quando comparados aos instrumentos dos demais grupos, independentemente do número de usos.

This study evaluated the flexural fatigue resistance of rotary instruments of nickel-titanium with different geometrical characteristics before and after use in artificial root canals. Systems Race (FKG Dentaire) and K3 (SybronEndo) with tip diameter of 0.25 mm, 0.04 taper and 25 mm of length were the rotary instruments selected. The instruments were divided into four groups (n = 12 each group), totaling forty-eight instruments, as follows: 01 Control Group (CG 01), new instruments unused Race; 02 Control Group (CG 02), new instruments unused K3 instruments ; Experimental Group 01 (SG 01), five uses Race instruments and Experimental Group 02 (SG 02), five instruments K3 uses. The simulation was carried out using artificial canals in resin, angle of curvature of 40 and a radius of 5 mm, using an electric motor with a speed of 350 rpm and 1 N.cm-1 of torque. All groups were tested for flexural fatigue in a device that allowed the instrument to rotate freely, reproducing the rotary movement in curved canals. The time spent until the fracture was measured by a chronometer. The ANOVA test showed significant difference between samples (p < 0.05). The use and feature geometric instruments influence the resistance to flexural fatigue (p < 0.05). The instruments of GC 01 (K3 unused) showed greater resistance to fatigue when compared to other groups of instruments, regardless of the number of use.

Geometric and dimensional characteristics of simulated curved canals prepared with proTaper instruments

OBJECTIVE: This study identified which regions of ProTaper instruments work during curved root canal instrumentation. MATERIAL AND METHODS: Twelve ProTaper instruments of each type, S1, S2, F1, and F2, were assessed morphometrically by measuring tip angle, tip length, tip diameter, length of each pitch along the cutting blades, and instrument diameter at each millimeter from the tip. Curved canals in resin blocks were explored with manual stainless steel files and prepared with ProTaper instruments until the apical end following four distinct sequences of instrumentation: S1; S1 and S2; S1, S2, and F1; S1, S2, F1, and F2. Image analysis was employed for measuring canal diameters. The diameters of the canals and diameters of the instruments were compared. Data were analyzed by one-way ANOVA and Tukey's test. RESULTS: No statistically significant difference was found between the canals and instrument diameters (p>0.05). The largest diameters in the end-point of the instrumented canals were obtained with F1 and F2 instruments and in the initial and middle thirds with S1 and S2 instruments. CONCLUSIONS: All instruments worked at the tip and along their cutting blades, being susceptible to fail by torsion, fatigue, or the combination of these two mechanisms.

Resistência à flexocompressão de instrumentos endodônticos indicados para canais atresiados e sua correlação com as características morfométricas / Buckling resistance of pathfinders and its geometry

O objetivo deste estudo foi avaliar a resistência à flexocompressão (flambagem) de instrumentos endodônticos empregados no cateterismo de canais radiculares atresiados e se esta varia conforme o comprimento. Flambagem é a deformação lateral apresentada por um instrumento quando submetido a uma força compressiva na direção de seu longo eixo. Foram utilizados instrumentos endodônticos C+File nº 10, K-File nº 10 (Dentsply-Maillefer, Suíça); CC+ nº 10 e C-Pilot nº 10 (VDW, Alemanha), HI-5 nº 10 (Miltex, EUA), Pathfinder CS K2 e Pathfinder SS (SybronEndo, EUA), sendo dez amostras de cada marca comercial em diferentes comprimentos. As dimensões dos instrumentos, tais como diâmetros, comprimento útil, comprimento da parte de trabalho, conicidades, ângulos de inclinação das hélices, ângulo da ponta, forma de seu vértice e presença de ângulo de transição foram determinadas por meio de um microscópio óptico com dispositivo micrométrico acoplado a um computador (Pantec, Panambra, Brasil). Detalhes da forma das pontas e forma das seções retas transversais foram obtidas por meio de um microscópio eletrônico de varredura (MEV - JEOL, JSM-5800, Tókio, Japão). O ensaio de flambagem foi realizado empregando-se uma máquina de ensaio universal (EMIC, DL 10.000, Paraná) e consistiu na aplicação de uma força crescente na direção axial dos instrumentos avaliados, sendo registrada por um software até o deslocamento de 1 mm. A análise dos resultados pelo ANOVA e Tukey revelou que a força máxima para flambar os instrumentos foi maior para os da marca comercial C+File tendo os instrumentos Pathfinder SS apresentado os resultados menos favoráveis. Provavelmente a geometria, que se mostrou completamente distinta para cada grupo de instrumentos, influenciou no comportamento dos mesmos, embora o comprimento não tenha interferido na resistência à flexocompressão.

The aim of this study was to evaluate the buckling resistance of endodontic intruments during the pathfinding of constricted root canals and its lenght influence. Buckling is the elastic deformation of an instrument due to the compressive strenght in its axial direction. The instruments surveyed and tested were: C+File #10, K-File #10 (Maillefer, Switerzland), CC+#10, C-Pilot #10 (VDW, Germany), HI-5 #10 (Miltex, USA) and Pathfinder CS K2 and SS (SybronEndo, USA). Ten instruments from different brands with different lenghts were measured through a optical microscope (Pantec, Panambra, Brazil) aiming to register the diameters, total and useful lenght, taper, helical angles and tip angle, whereas tip details and cross sections were obtained through an electronic microscope MEV (JEOL, JSM-5800). The buckling test was performed at an universal testing machine (EMIC, DL 10.000, Brazil). The maximum load during the elastic deformation was measured by a software while applying increasingly pressure in the axial direction of each instrument till a 1mm deformation. The ANOVA e Tukey test analized the results and revealed that the C+File presented the highest buckling resistance while Pathfinder SS presented the worst results. Different designs might interfere with the results but, in general, the lenght did not have statistical influence.

Influência da conicidade de instrumentos endodônticos de NiTi na flexibilidade e no número de ciclos à fadiga / Influence of NiTi endodontic instrument taper on flexibility and fatigue resistance

O objetivo deste trabalho foi avaliar a influência da conicidade de instrumentos endodônticos de NiTi mecanizados na flexibilidade, no número de ciclos para ocorrer a fratura por fadiga e no comprimentodo segmento fraturado. Foram utilizados 30 instrumentos K3 (Sybron Dental Specialyties, Kerr, México) denúmero 25, comprimento de 25 mm e conicidade de 0,02 - 0,04 e 0,06 mm/mm. A flexibilidade dos instrumentosfoi avaliada em ensaio de flexão em cantilever. O número de ciclos para ocorrer a fratura por fadigafoi determinada em ensaio de flexão rotativo. Os resultados obtidos indicaram que a flexibilidade e a vidaem fadiga diminuiu com o aumento da conicidade e o comprimento do segmento fraturado aumentou com oaumento da conicidade dos instrumentos.

The aim of this study was evaluate the influence of engine-driven instrument taper on flexibility, cyclesto fracture occur and length of the fractured segment. Thirty K3 (Sybron Dental Specialties, Kerr, Mexico) instruments size 25 taper .02, - .04 e .06 with 25mm in length were used. The flexibility was evaluated in cantileverbending test and the cycles to fracture occur was obtained in rotating-bending test. The results indicatedthat the flexibility and the fatigue resistance decreased in the instruments with more taper, in the other hand,the length of the fractured segment increased in the instrument with more taper.

Surface finishing of unused rotary endodontic instruments: a SEM study

During endodontic therapy, cleaning of root canals is performed using endodontic files and auxiliary chemical substances, and it is important that the endodontist be familiar with the instruments used in daily practice. This study evaluated, under scanning electron microscopy (SEM), the quality of the surface finishing of unused rotary endodontic instruments. Fifty sizes 20, 25 and 30 rotary files from different commercial brands (ProFile, Protaper, Race, Hero and K3 Endo) were removed directly from their packages and had their final 3 mm examined with a scanning electron microscope at x190 magnification with no previous preparation. The images were evaluated by 3 skillful, calibrated, blinded observers according to the following criteria: cutting edge, debris, grooves, microcavities, tip shape, tip position, scraping and transition angle. Data were recorded in worksheets designed for the study. Irregular edges were observed in 50-100 percent of the files. Except for ProFile, all commercial brands presented surface debris in 100 percent of samples. Only Race files showed no grooves or microcavities. K3 Endo files presented the best tip centralization. Excetp for ProTaper files, all commercial brands presented blunt-cutting edges in 100 percent of samples. All types of files presented surface scraping. K3 Endo files and Protaper had a high percentage of transition angle. Based on the evaluation criteria used in the present study, most samples presented a minimum of 2 alterations and a maximum of 7 alterations per instrument. Under the tested conditions, the quality of the surface finishing of the examined instruments was not as expected, given that no instrument was free of imperfections and most of them presented at least 2 and up to 7 types of surface defects. These results suggest that the manufacturing process and the packaging conditions of rotary endodontic instruments are far from ideal.

Durante a terapia endodôntica, a ação de limpeza é realizada com os instrumentos endodônticos auxiliada por substâncias químicas. Sendo assim, é importante que o endodontista conheça como são os instrumentos. Este trabalho visou avaliar a qualidade do acabamento de superfície de instrumentos endodônticos rotatórios por meio de microscopia eletrônica de varredura. Foram selecionados, 50 instrumentos endodônticos rotatórios nos números de 20, 25 e 30, das marcas Profile, Protaper, Race, Hero e K3 Endo, da forma como são encontradas no mercado e sem nenhum preparo prévio. Os instrumentos tiveram seus 3 milímetros finais fotomicrografados em microscópio eletrônico de varredura com ampliação de x190. As imagens foram avaliadas por três profissionais especialistas, e os resultados anotados em planilhas. A metodologia aplicada permitiu concluir que todos os instrumentos das marcas comerciais avaliadas apresentaram inadequações no acabamento da superfície. Cabe aclarar que, observando os critérios selecionados utilizados para avaliação a maioria das amostras apresentaram o mínimo de duas alterações e o máximo de sete por instrumento avaliado.

Endodontic file in an appendix / 대한내과학회지

Once ingested foreign bodies pass through the stomach, 80 to 90 percent of them will exit via the gastrointestinal tract and they are excreted naturally in 7-10 days; surgical treatment is not required in most case. But once foreign bodies permeate the appendix, it is difficult for them to be excreted again to the cecum; therefore, this can possibly cause appendicitis or perforation. Especially in case of long, pointed, thin, stiff, sharp and/or metalic objects, the risk of perforation will increase. We attempted to remove an endodontic file in the appendix by colonoscopy. This was done in a patient who came to hospital because he swallowed an endodontic file during endodontic therapy. But we failed to retrieve it, and so we got rid of the foreign body by performing elective surgery before the occurrence of complications. We report here on surgical removal of an apppendiceal foreign body along with a review of the literature.