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Studies related to the prevalence of leptospirosis in the semiarid region showed that even during long periods of drought, the disease has a remarkable frequency in herds in the region. It is a neglected disease and the extent of its effects in the Brazilian semiarid region is not known. The dynamics of this agent is well studied in the urinary tract, however, there are not many studies regarding the genital tract in female goats. Observing this scenario, the present work aimed to diagnose Leptospira spp. in female goats kept in the Brazilian semiarid region by means of serological, molecular and isolation techniques. Blood samples, vaginal fluid, urine and fragments of organs from the genitourinary tract were collected from 40 goats destined for slaughter. Microscopic agglutination test (MAT) was used as a serological technique, with a battery of 24 serovars. The Polymerase Chain Reaction (PCR) of the vaginal fluid, urine and organ fragments was performed, as well as the bacterial growth of these same products in a selective medium. Isolation positive samples were subjected to PCR. It was observed that two (5%) animals were serologically positive for the Pyrogenes serogroup. A total of 29 (72.5%) animals were PCR positive, with DNA present in 51/160 (31.8%) samples from the genital tract and 34/120 (28.3%) from the urinary tract, with no statistical difference. For bacterial growth, 22/40 (55%) animals were positive for growth, with morphology being observed in 19/160 (11.8%) for the genital tract and 16/120 (13.3%) for the urinary tract, with no statistical difference. Two uterus samples showed 99% similarity with L. interrogans after sequencing. Thus, female goats kept under semiarid conditions were positive for Leptospira spp, with positive samples from both the urinary and genital tracts, which possible is an alternative way of adapting and maintaining the agent for severe and adverse conditions.

Caprine arthritis encephalitis and Maedi-Visnaare lentiviruses affecting goats and sheep, respectively. Despite the literature having studies about these diseases, there is a constant demand and the need to study the health status of flocks that exploit economically. Therefore, this study aimed to assess the frequency of small ruminant lentiviruses explored in regional locations of Chapadinha and Itapecuru Mirim, that compose the microregion of Low Parnaíba, Maranhão, Brazil, as well as analyze the spatial distribution of outbreaks in the studied regions. Therefore, 241 properties were visited, where blood was collected in 1150 sheep and 1260 goats and tested by agar gel immunodiffusion (AGID). Epidemiological questionnaire was applied and collected the geographic coordinates. There was a low frequencyfor lentivirus, with 0.39% (5/1260) of goats and 0.08% (1/1150) of sheep. Regarding the spatial analysis, the reagent flocks were distributed in strategic cities for commercialization throughout the microregion. There was a low occurrence of lentiviruses.The municipalities of Cantanhede and Pirapemas of the regional of Itapecuru Mirimand Brejo and Magalhães de Almeida had reagent flocks for CAE. Whereas the municipality of Matões do Norte presented flock reagent to Maedi-Visna, this belonging to the regional of Chapadinha.

The objective of this work was to evaluate the efficiency technique of fixation of the caudal curvature of the sigmoid flexure with myectomy of the penis retractor muscle and the performance of teaser bulls after surgery, through the detection of females in estrus, without performing the copulation. 12 teaser buffaloes were used without defined breed, with an average age of 20 months, weighing on average 200 kg. The animals were subjected to food and water fasting for 12 hours to provide tranquilization in advance. The surgical procedure consisted of the exteriorization of the sigmoid flexure, myectomy of penis retractor muscle and fixation of the caudal curvature of the penis sigmoid flexure. Of the 12 evaluated teaser buffaloes in the libido test, 100% performed the flehmen reflex, mount attempt, incomplete and complete jump with total inability of the penis exposure. It was concluded that this technique can be used safely, having simplicity in its execution, effective results and mainly low cost, not interfering in the animals’ libido. The animals when tested as teaser buffaloes kept the libido during the experimental period with total inability of exposure of the penis.

Bovine leptospirosis causes economic losses and raises public health concerns. It is possible that there are peculiarities in the epidemiology of leptospirosis in regions with a semiarid climate, such as the Caatinga biome in Brazil, where the climate is hot and dry, and the etiological agent require alternative routes of transmission. This study aimed to close knowledge gaps to the diagnosis and epidemiology of Leptospira spp. infection in cows from the Caatinga biome, Brazil. Samples of the blood, urinary tract (urine, bladder and kidney) and reproductive tract (vaginal fluid, uterus, uterine tube, ovary and placenta) were collected from 42 slaughtered cows. Diagnostic tests included were the microscopic agglutination test (MAT), polymerase chain reaction (PCR) and bacterial isolation. Anti-Leptospira spp. antibodies were found in 27 (64.3%) of the animals analyzed using MAT at a 1:50 dilution (cut-off 50), while 31 (73.8%) animals had at least one organ/fluid where the presence of Leptospira spp. DNA was identified, and 29 animals (69%) were positive at bacteriological culture. The highest sensitivity values for MAT were obtained at the cut-off point of 50. In conclusion, even under hot and dry climate conditions, it is possible that Leptospira spp. can spread through alternative routes such as venereal transmission; moreover, a cut-off of 50 is recommended for the serological diagnosis of cattle from the Caatinga biome.

Made available in DSpace on 2021-06-25T11:07:48Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Even in the adverse environmental conditions of the semiarid region, leptospires can survive and spread by alternative routes of transmission, such as sexual in ewes, however, there is no data on rams. Thus, the present study aimed to evaluate the use of serological, molecular and microbial tools applied to diagnosis of Leptospira sp. Infection in rams maintained in semiarid conditions. Biological samples of urinary (urine, kidney and bladder) and genital (vas deferens, epididymis tail and vesicular gland) tracts were collected from 40 slaughtered rams for polymerase chain reaction (PCR) and bacterial isolation, as well as blood samples for antibody detection through microscopic serum agglutination test (MAT). Anti-Leptospira antibodies were found in five (12.5%) animals with antibody titer of 50 and 2 (5%) for the titer 100 for serogroups Pyrogenes, Ballum, Icterohaemorrhagiae and Australis. Leptospira sp. DNA was found in PCR of organs and urine of 30 (75%) animals. Overall, 240 fragments of organs from the urinary and genital tracts and urine were evaluated, with 93 (38.7%) positive samples, being 48/120 (40%) for the urinary tract and 45/120 (37.5%) for the genital. There was no statistically significant difference between the tracts. A bladder sample was sent for sequencing and showed 99% similarity with L. interrogans. Of the 240 cultures evaluated, 59 (24.5%) had leptospire growth, being that 23 (39%) were confirmed in PCR. Considering the PCR of organs and urine and bacterial growth as gold standards, the cut-off 50 in MAT showed greater sensitivity when compared to cut-off 100, regardless of the material used. The great proportion of leptospiral DNA in organs, urine and culture and bacterial growth from the genital tracts reinforce its importance as an extra-renal site and highlights the possible role of rams in venereal transmission, as well as the sensitivity of the cut-off 50 suggested its adoption in the serology of rams maintained in semiarid conditions. Universidade Federal de Campina Grande (UFCG) Centro de Saúde e Tecnologia Rural (CSTR), Av. Universitária, s/n, Santa Cecília Universidade de São Paulo (USP), Av. Prof. Almeida Prado, 1280 Universidade Estadual Paulista (Unesp), Av. Prof. Mário Rubens Guimarães Montenegro, s/n, campus de Botucatu Universidade Federal da Paraíba (UFPB) Centro de Ciências Agrárias (CCA), Rodovia BR 079, Km 02 Universidade Estadual Paulista (Unesp), Av. Prof. Mário Rubens Guimarães Montenegro, s/n, campus de Botucatu

Paratuberculosis is an incurable infectious disease that affects several species, including goat (Capra hircus). The etiologic agent is Mycobacterium avium subspecies paratuberculosis (MAP) that has tropism for the intestine, causing anorexia, progressive weight loss and death. In goats, the main transmission route is the ingestion of water and food contaminated by infected feces. Affected animals also eliminate the agent through milk, with a potential biological risk to public health. Thus, the aim of this study was to conduct a research of the literature available in electronic media for a systematic review, followed by a meta-analysis of the results found on prevalence and diagnostic tests adopted in the detection of MAP antibodies and DNA in goat milk. The following search parameters were used: “Mycobacterium avium subsp. paratuberculosis” AND (goat OR small ruminant) AND (milk OR pasteurized milk). Strictly obeying pre-established criteria, 437 articles were selected from the respective electronic databases of scientific content: ScienceDirect (285), PubMed (68), Web of Science (60) and Scopus (24), of which nine papers were elected to the construction of the systematic review and meta-analysis. The prevalence of MAP antibodies in milk detected by milk-ELISA ranged from 1.1 to 67.7% and the prevalence of MAP DNA in goat milk detected by MAP-specific polymerase chain reaction (PCR) ranged from 1.94 to 37.74%. A meta-analysis indicated a combined MAP infection prevalence of 8.24%, but with high heterogeneity among study findings (I2 = 98.7%). The identification of the MAP in goat milk implies the need for surveillance of the agent in order to prevent economic losses and impact on public health.

The objective of this research was to estimate the frequency, risk factors and mapping of outbreaks in ovine flocks in the State of Maranhao, Brazil, related to Leptospira spp. A total of 575 samples of blood serum from sheep were collected, from 116 flocks, and 20 municipalities. An epidemiological questionnaire was applied to verify the association of risk factors. Microscopic Agglutination Test (MAT) was used for 24 serovars of Leptospira spp. 100% of the flocks (116) and 94.43% of animals (543/575) were reagents for at least one of the 24 serovars tested. The most frequent serovars were Sentot (236, 41.04%), Hadjo (197, 34.26%), Adamana (178; 30.95%), Pomona (158, 27.47%) and Autumnallis (148, 25.73%). The presence of rodents, felines, goats, pigs and wild animals had a statistically significant association (p < 0.05) with the occurrence of Leptospira spp. It was concluded that the frequency of Leptospiraspp was high in sheep from the State of Maranhao. However, all municipalities had infected animals, therefore, it is considered necessary to implement sanitary measures for the control and prevention of this disease in ovine flocks in the state of Maranhao.

Leishmaniases are a group of diseases of zoonotic importance caused by over 20 species of protozoa of the genus Leishmania, in which domestic dogs are considered to be the main reservoir for the disease. However, the involvement of other vertebrates as reservoirs for these parasites has also been investigated. Therefore, the objective of the present study was to carry out a systematic review with meta-analysis on occurrences of leishmaniasis in equids. The case reports described animals with cutaneous symptoms of leishmaniasis (papules, nodules, ulcers or crusts) that regressed spontaneously, located mainly on the head and limbs, from which three species of protozoa were identified in the lesions: Leishmania braziliensis, Leishmania infantum and Leishmania siamensis. In turn, the meta-analysis showed a combined prevalence of 25%, although with high heterogeneity among the studies, which was attributed to the use of different methods for diagnosing the disease. Leishmaniasis in equids is a benign disease but it should be included in the differential diagnosis of cutaneous diseases among these species. Seroepidemiological studies are important in investigating and monitoring suspected exposure of these hosts to the parasite, especially in endemic areas. However, there is also a need to standardize diagnostic methods. Resumo As leishmanioses são um grupo de doenças de importância zoonótica causadas por mais de 20 espécies de protozoários do gênero Leishmania, sendo o cão doméstico considerado o principal reservatório da doença. No entanto, diversas pesquisas têm investigado o envolvimento de outros vertebrados como reservatórios do parasita. Portanto, o objetivo do presente estudo foi realizar uma revisão sistemática com meta-análise da ocorrência de leishmaniose em equídeos. Os relatos de caso descreviam animais com sintomas cutâneos de leishmaniose (pápulas, nódulos, úlceras, crostas) que regrediam espontaneamente, localizadas principalmente na cabeça e membros, sendo identificadas três espécies do protozoário nas lesões: Leishmania braziliensis, Leishmania infantum e Leishmania siamensis. Por sua vez, a meta-análise evidenciou uma prevalência combinada de 25%, porém com alta heterogeneidade entre os estudos, atribuída às diferenças nos métodos utilizados no diagnóstico da doença. A leishmaniose em equídeos é uma doença benigna, porém deve ser incluída no diagnóstico diferencial de doenças cutâneas nessas espécies. Os estudos soroepidemiológicos são importantes para investigar e monitorar a suspeita de exposição desses hospedeiros ao parasita, principalmente em áreas endêmicas, porém há necessidade de padronização dos métodos de diagnóstico.

Torsional overload is a fracture representative parameter for instruments in single-file techniques. Objective The aim of this study was to assess the influence of clinical use, in vivo, on the torsional behavior of Reciproc and WaveOne instruments considering the possibility that they degraded with use. Material and Methods Diameter at each millimeter, pitch length, and area at 3 mm from the tip were determined for both types of instruments. Twenty-four instruments, size 25, 0.08 taper, of each system were divided into two groups (n=12 each): Control Group (CG), in which new Reciproc (RC) and WaveOne Primary (WO) instruments were tested in torsion until rupture based on ISO 3630-1; and Experimental Group (EG), in which each new instrument was clinically used to clean and shape the root canals of one molar. After clinical use, the instruments were analyzed using optical and scanning electron microscopy and subsequently tested in torsion until fracture. Data were analyzed using one-way analysis of variance at a=.05. Results WO instruments showed significantly higher mean values of cross-sectional area A3 (P=0.000) and smaller pitch lengths than RC instruments with no statistically significant differences in the diameter at D3 (P=0.521). No significant differences in torsional resistance between the RC and WO new instruments (P=0.134) were found. The clinical use resulted in a tendency of reduction in the maximum torque of the analyzed instruments but no statistically significant difference was observed between them (P=0.327). During the preparation of the root canals, two fractured RC instruments and longitudinal and transversal cracks in RC and WO instruments were observed through SEM analysis. Conclusion After clinical use, no statistically significant reduction in the torsional resistance was observed.

As propriedades mecânicas dos instrumentos endodônticos são afetadas por fatores como diâmetro, design, composição química, e tratamentos termomecânicos aplicados durante o processo de fabricação. O objetivo deste trabalho foi avaliar a flexibilidade e a resistência torcional de instrumentos de NiTi Reciproc (RC), Wave One (WO) e ProTaper Universal (PTU), novos e após o uso clínico. A composição química dos instrumentos foi analisada por espectroscopia de energia de raios X (EDS), as fases presentes identificadas por difração de raios X (DRX) e as temperaturas de transformação determinadas por calorimetria exploratória diferencial (DSC). Imagens das seções longitudinal e transversal foram empregadas para determinar o diâmetro e a área a 3 mm da ponta (D3 e A3), posição onde as solicitações mecânicas se concentram durante o uso clínico e os instrumentos são apreendidos nos testes. O comportamento mecânico foi avaliado através de ensaios de flexão e torção até a ruptura, de acordo com a especificação ISO 3630-1. Os instrumentos RC, WO e PTU apresentaram composição química semelhante e fase como principal constituinte à temperatura ambiente. No entanto, os instrumentos Reciproc e WaveOne apresentaram um aumento relevante nas temperaturas de transformação, sugerindo a presença da fase B19, coexistindo com a fase austenítica. Apesar de apresentarem D3 semelhantes, a análise estatística dos valores de A3 entre os pares de instrumentos analisados mostrou diferença significativamente menor para os instrumentos RC. Os instrumentos RC foram significativamente mais flexíveis, possivelmente devido ao tratamento termomecânico a que foram submetidos os fios utilizados na fabricação dos mesmos (MWire), além da morfologia de sua sessão tranversal, seguidos por WO, que também são fabricados a partir do fio M-Wire, e PTU, nesta ordem. Dentre os instrumentos novos, os PTU apresentaram valores de torque máximo, quando ensaiados em torção, significativamente menores. Os instrumentos PTU apresentaram os maiores valores de deflexão angular, seguidos pelos instrumentos RC e WO, nesta ordem. Todos os sistemas após serem utilizados na prática clínica apresentaram redução da resistência torcional. Entretanto, a comparação estatística entre os valores de torque máximo para os instrumentos novos e após uso clínico, não apresentou diferença estatisticamente significativa para nenhum dos sistemas avaliados. Com relação à deflexão angular, a comparação entre instrumentos novos e após uso clínico, mostra uma redução dos valores desse parâmetro após o uso clínico, com exceção dos instrumentos RC. Entretanto, as análises estatísticas mostraram não haver diferenças significativas entre os pares de instrumentos analisados. The mechanical properties of the endodontic instruments are affected by factors such as diameter, design, chemical composition and thermo-mechanical treatments applied during the manufacturing process. The main goal of this study was to assess the flexibility and torsional resistance of the NiTi Reciproc (RC), Wave One (WO) and ProTaper Universal (PTU) instruments, new and after clinical use. The instruments chemical composition was analyzed with X-Ray energy spectroscopy (EDS), the present phases were determined by X-Ray Diffractions (DRX) and the transformation temperatures were obtained with differential scanning calorimeter (DSC). Images from the longitudinal and transversal sections were used for determining the diameter and the area at 3mm from the tip (D3 and A3), the position where the mechanical requests are focused in clinical use and where the instruments are apprehended during the tests. The mechanical behavior has been evaluated through simulation of bending and torsion until rupture according to ISO 3630-1. The RC, WO and PTU instruments have presented a similar chemical composition with the predominance of phase at room temperature. However, Reciproc and Waveone instruments showed a significant increase in transformation temperatures, suggesting the presence of B19 phase, coexisting with the austenitic phase Despite showing similar D3, statistical analysis of the values of A3 between pairs of instruments analyzed showed significantly lower difference for RC instruments. The RC instruments were significantly more flexible, possibly due to the thermomechanical treatment applied to the wire (M-Wire) used in their manufacture process in addition to their cross section design, followed by WO instruments, which are also made of M-Wire, and PTU instruments, in that order. Among the new instruments, PTU showed significantly lower maximum torque values in torsion tests. PTU instruments presented the highest angular deflection values, followed by RC and WO instruments, in that order. All systems reduced their torsional strength after clinical use. However, statistical comparison between the maximum torque values for new and after clinical use instruments, showed no statistically significant difference for any of the evaluated systems. Regarding the angular deflection, the comparison between new and after clinical use instruments demonstrated a reduction of the values of this parameter after clinical use, with the exception of RC instruments. However, statistical analysis showed no significant differences between the pairs of instruments analyzed. Key-words: NiTi instruments, Flexibility, Torsional resistance, Reciproc

Este trabalho teve como objetivo a avaliação das características geométricas, das propriedades estruturais, físicas, químicas e mecânicas dos instrumentos endodônticos de NiTi Twisted File (SybronEndo, Orange, CA) e RaCe (FKG, La Chaux-de-Fonds, Switzerland). A composição química da liga NiTi foi analisada semi-quantitativamente por espectroscopia de energia de raios-X (EDS), as fases presentes foram identificadas através de análises por difratometria de raios-X (DRX), as temperaturas de transformação foram determinadas por calorimetria exploratória diferencial (DSC) e o acabamento superficial foi avaliado por microscopia eletrônica de varredura (MEV). As características geométricas e dimensionais dos instrumentos foram analisadas através do software ImagePro Plus 6.0 (Media Cybernetics, Silver Spring, MD, EUA). A resistência à fadiga foi determinada utilizando um dispositivo de bancada para testes em fadiga. Os dados foram analisados pelo teste ANOVA com um nível de confiança de 95%. Observou-se que os instrumentos RaCe apresentaram padronização geométrica e características superficiais compatíveis com as descritas pelo fabricante. Já os instrumentos Twisted File não apresentaram uniformidade em todos os parâmetros dimensionais analisados. As ligas utilizadas na confecção dos dois Sistemas apresentaram composições químicas semelhantes, correspondendo às fornecidas pelos fabricantes. A análise por difração de raios X (DRX) confirmou que à temperatura ambiente os instrumentos TF e RaCe apresentaram como principal constituinte a austenita. Embora o fabricante do Sistema TF relate que seus instrumentos são compostos por Fase R, sua presença não foi detectada nas análises realizadas. Os valores médios das temperaturas de transformação dos dois sistemas confirmam que a liga é austenítica à temperatura ambiente. Na análise por MEV, a regularidade superficial dos instrumentos RaCe, submetidos ao polimento eletrolítico não pôde ser observada nos instrumentos TF. Nos ensaios de fadiga, os instrumentos TF apresentaram uma vida em fadiga maior que os instrumentos RaCe de diâmetros semelhantes. Pode ser sugerido que os processos termomecânicos empregados na fabricação dos mesmos influenciaram o comportamento mecânico, aumentando a resistência à fadiga destes instrumentos. This work was a study of structural characteristics, physical and mechanical properties of NiTi endodontic instruments Twisted File 25/.06 and .08, RaCe 25/.04 and .06. The geometric and dimensional characteristics of the instruments were analyzed and measured by the software ImagePro Plus 6.0 (Media Cybernetics, Silver Spring, MD, USA). The topographic features were evaluated by scanning electron microscopy (SEM), chemical composition was analyzed semi-quantitatively by proton energy X-ray (EDS), the crystalline structure of the alloy identified by X-ray diffraction (XRD) while the transformation temperatures were determined by differential scanning calorimetry (DSC). Fatigue strength was evaluated in a bench device using an artificial canal with a radius of curvature of 5mm and 45° angle. RaCe instruments were standardized geometric and surface characteristics consistent with those described by the manufacturer (FKG, La Chaux-de-Fonds, Switzerland). Already instruments Twisted File not presented the geometric characteristics and surface suggested by the manufacturer (SybronEndo, Orange, CA). The instruments of the two systems were in satisfactory stoichiometric and transformation temperatures favor the occurrence of superelasticity. Although the manufacturer Twisted File System report that their instruments are composed of R-Phase, the presence of this phase was not detected in tests carried out. The diffraction patterns obtained with instruments and Twisted File RaCe demonstrated the presence of peaks of higher intensity of -Phase. In fatigue tests, the resistance of the instruments decreased with increasing size. The results obtained and analyzed by ANOVA, with a coefficient of reliability of 95%, indicated that the TF 25/.06 instruments showed a fatigue life 16,0% higher when compared to RaCe 25/.04 instruments and tools TF 25/.08 fatigue life showed a 18,0% increase compared to RaCe 25./06 instruments.

A capacidade e eficiência de corte dos instrumentos endodônticos de Níquel-Titânio (NiTi) são complexas e relacionadas a diversos fatores, como a técnica de instrumentação utilizada e as características geométricas e dimensionais dos instrumentos. Neste trabalho, o objetivo foi avaliar a ação de corte através do torque exercido durante o preparo de canais radiculares por instrumentos BioRaCe, (FKG Dentaire Swiss Endo La Chaux-de-Fonds, Suíça) BR0 25/.08, BR1 15/.05, BR2 25/.04, BR3 25/.06, BR4 35/.04 e BT-RaCe (FKG Dentaire Swiss Endo La Chaux-de-Fonds, Suíça) BTR1 10/.06, BTR2 35/.00 e BTR3 35/.04. Inicialmente, os instrumentos foram caracterizados com relação ao diâmetro a cada milímetro da parte ativa e comprimento de pitch. Os instrumentos foram fotografados e a análise das imagens foi realizada com o software ImageJ. Os ensaios de eficiência de corte foram realizados em 20 pré-molares com duas raízes distintas com curvatura gradual e discreta entre 10º e 25º (classe I) e comprimento total dos canais entre 19 e 23mm, selecionados do banco de dentes da FOUFMG. Após radiografia digital inicial, foi realizado acesso coronário e odontometria com limas manuais de aço inoxidável K#10 e K#15. Dez dentes foram instrumentados seguindo a técnica preconizada pelo fabricante para cada sistema. Um multímetro, acoplado ao motor endodôntico, registrou o torque requerido por cada instrumento durante o preparo dos canais. A ação de corte e o comportamento dos instrumentos durante o preparo dos canais foram avaliados através das curvas torque versus tempo. Os resultados da caracterização geométrica e dimensional dos instrumentos indicaram que a medida dos mesmos é compatível com os valores preconizados pelo fabricante. Na análise do comprimento de pitch, as limas mostraram arestas de corte alternadas e progressivas, exceção apenas para a BTR2, cujo pitch foi constante. Quanto ao tempo de utilização dos instrumentos, os resultados indicaram que os sistemas BioRaCe e BT-RaCe demonstraram diferenças nos tempos dos ensaios de eficiência de corte, devido, principalmente, à diferença do número de instrumentos utilizados em cada sequência. Por fim, não houve diferença estatística entre a ação de corte dos instrumentos que demandaram maior torque médio durante a instrumentação, BR3 para o sistema BioRaCe e BTR3 para o sistema BT-RaCe. A diminuição do número de instrumentos para o preparo de canais mostrou, nas limitações deste estudo e nas sequencias avaliadas, um torque máximo seguro para o uso clínico, bem como a diminuição do tempo clínico. The cutting ability and efficiency of Niquel Titanium (NiTi) endodontic instruments are complex and related to many different factors such as the instrumentation technique and the geometric and dimensional characteristics of the instruments. The goal of the present work was to assess the cutting action through the torque exerted during the preparation of root canals with BioRaCe instruments, (FKG Dentaire Swiss Endo La Chaux-de-Fonds, Suíça) BR0 25/.08, BR115/.05, BR2 25/.04, BR3 25/.06, BR4 35/.04 e BT-RaCe (FKG Dentaire Swiss Endo La Chaux-de-Fonds, Suíça) BTR1 10/.06, BTR2 35/.00 e BTR3 35/.04. Initially, the instruments were characterized according to the diameter of each millimeter of the active part and pitch length. Instruments were photographed and images were analized by the ImageJsoftware. Cutting efficiency assays were performed with 20 upper premolares with two separate roots with a gradual curvature ranging from 10º e 25º (class I) and total canal length between 19 and 23mm, selected from the FOUFMG tooth bank. After the initial digital radiograph the coronal access was performed, follow by the working length determination with manual stailess steel K#10 and K#15 files. Ten teeth were instrumented according to the manufacturers recommendation for each system. A multimeter, coupled to the endodontic motor, recorded the torque required by each instrument during root canal preparation. The cutting efficiency and the behaviour of the instruments during the preparation were assessed by the torque versus time curves. Results indicate that the geometrical and dimensional characterization of the instruments are compatible to the values advocated by the manufacturer. In the pitch length analysis, files showed alternate progressive cutting flutes, only exception being, that had a constant pitch. As for the cutting time required by the instruments, results revealed that BioRaCe and BT-RaCe systems showed differences in the cutting efficiency time assays, mostly due to the difference in the number of instruments used for each sequence. Last but not least, there were no statistical differences in the cutting assays of instruments that demanded higher average torque during the instrumentation, BR3 for the BioRaCe system and BTR3 for the BT-RaCe system. The reduced number of instruments for root canal preparation, within the constraints imposed by this study and by the sequences evaluated, showed a safe maximum torque for clinical use and a decreased treatment time.

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 nasmesmas 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 torquefoi 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 defratura 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.