O objetivo deste estudo in vivo foi investigar as imagens obtidas por microtomografia computadorizada (micro-TC) no estudo da anatomia apical de dentes humanos portadores de polpa viva e mortificada. Trinta e cinco dentes humanos unirradiculares ou multirradiculares que tiveram suas raízes separadas totalizando quarenta e uma raízes foram rigorosamente pré-selecionadas e divididas em dois grupos: com polpa viva (PV) n = 21 e com polpa mortificada (PM) n = 20. Os dentes de ambos os grupos foram escaneados pelo sistema de microtomografia computadorizada (SkyScan 1172) com resolução de 6,7m e suas imagens reconstruídas para a análise da região apical nos cortes sagital e coronal. O diâmetro do forame apical (FA) e da junção cemento-dentina (JCD) foram medidos bem como suas distâncias (extensão do cemento) em ambos os lados da raiz. Posteriormente a coroa dos dentes foi cortada no seu colo anatômico e suas raízes foram medidas com paquímetro eletrônico e a odontometria realizada com localizador eletrônico apical (RomiApex A15). A subtração desses dois dados foi correlacionada com as medidas obtidas pela micro-TC na avaliação da posição da JCD. As raízes foram preparadas para avaliação histológica em cortes longitudinais de 6m de espessura e corados com HE. Os cortes que apresentaram a emergência do FA foram fotografados digitalmente e as imagens correspondentes de micro-TC foram sobrepostas com o intuito de ilustrar a metodologia utilizada. As medidas da micro-TC foram realizadas por dois examinadores devidamente instruídos. A concordância inter-examinadores foi confirmada pelo coeficiente de correlação intraclasse (ICC) e as medidas foram comparadas pelo teste de Mann-Whitney (teste de Wilcoxon rank sum - p0,05). Os resultados indicaram que não houve diferença estatisticamente significante quanto à extensão do cemento intrarradicular nos grupos quer de polpa viva como mortificada com distâncias de 0,32±0,1mm e 0,36±0,16mm respectivamente. As medidas realizadas pelo localizador apical, a 1,0mm aquém, garantiu o estabelecimento do limite dentro do canal dentinário. Os resultados encontrados para o diâmetro do forame apical foi 619,32±32 m para o grupo PV e 630,542±140,99m para o grupo PM sem diferença estatisticamente significante. O diâmetro do canal radicular na junção cemento-dentina não apresentou diferença estatisticamente significante entre PV com 330,37±126,62m e PM com 357,62±996,14m. O posicionamento da JCD em relação ao FM não foi influenciado pelo estado de vitalidade pulpar. / This ex vivo study aimed to investigate the apical anatomy of vital and necrotic human roots by microcomputed tomography (micro-CT). Thirty-five single or multirooted human teeth that had their roots separated totaling forty-one roots were carefully pre-selected and divided into two groups: vital pulp (VP) n = 21 and necrotic pulp (NP) n = 20. Both groups were scanned by microcomputed tomography system (SkyScan 1172) with 6.7m resolution and the apical region was analyzed by reconstructed images in sagittal and coronal sections. The diameters of the apical foramen (AF) and root canal at the cemento-dentino canal junction (CDJ) were measured. The cementum extension into the root canal was measured on both sides of the root canal. Thereafter the teeth crown was cut at the cemento-enamel junction, the length of roots was measured with a caliper and the working length was performed by an electronic apex locator (RomiApex A15). The result of the subtraction of these two data was correlated with measures obtained by micro-CT in the evaluation of CDJ position. The roots were sectioned in longitudinal histological sections of 6m thickness and stained with HE. The sections that showed the emergence of the FA were digitally photographed and the corresponding micro-CT sections were correlated by superimposition in order to illustrate the methodology. Measures of micro-CT scans were performed by two calibrated examiners. The interexaminers agreement was confirmed by intraclass correlation coefficient (ICC) and measurements were compared by Mann-Whitney test (Wilcoxon rank sum test - p0.05). The results indicated that there was no statistically significant difference in relation to the extension of cementum into the root canal in both goups VP or NP with average distances of 0.32±0.1mm and 0.36±0.16mm respectively. The measurements taken by the apex locator 1 mm from the apex were within the limits of dentinal canal. The diameter of the apical foramen corresponded to the NP group was 619.32±201.61m and 619.32±140.99m on average, not statistically significant. The average diameter of the root at the CDJ was 330.37±126.62m for VP and 357.62 ±96.14m for NP groups presenting no statistically significant difference. The distance of the CDJ in relation to AF was not influenced by the pulp vitality.

Este estudo objetivou avaliar a influência do diâmetro do forame e do instrumento endodôntico na leitura odontométrica de dois aparelhos localizadores apicais eletrônicos. Foram utilizados 40 dentes incisivos inferiores, divididos em 4 grupos, de acordo com o diâmetro do forame apical (100, 200, 300 e 400 µm). Após a abertura coronária desses dentes e o acesso aos canais radiculares, realizou-se a medição do comprimento dos mesmos com auxílio de um microscópio clínico com ampliação de 7,8X, da incisal até que a ponta da lima surgisse no forame apical. Os dentes foram colocados em potes individuais contendo solução de ágar a 1% em solução salina de fosfato tamponado, mantendo-se cerca de 2/3 de suas raízes imersas na solução para que pudesse ser feita a leitura com o Root ZX® (J.Morita, Japão) e o NovApex® (Fórum, Israel). Os mesmos foram medidos com limas nº10 até que a distância de 0,5 mm do ápice fosse acusada no display dos aparelhos. Uma outra medida foi realizada nos dentes utilizando-se lima nº10 e limas com diâmetros correspondentes ao diâmetro dos forames (200µm, 300µm e 400µm). Para a análise estatística foi empregado o teste de Análise de Variância a dois critérios para o confronto global entre os aparelhos e o emprego da lima nº10 em todos os dentes e teste de Tukey para as comparações individuais. Os resultados demonstraram diferença estatística na precisão dos dois aparelhos com um resultado mais preciso para o Root ZX® (p<0,05). Dentes com forame, de menor diâmetro, apresentaram uma medida mais precisa com o localizador apical e dentes com forame de maior diâmetro apresentaram uma maior discrepância na medida. O emprego de limas tipo K nº10 nos dentes com forames de diâmetros maiores apresentaram maior precisão na medição quando comparadas às limas coincidentes aos diâmetros dos forames para o aparelho Root ZX®. Para o NovApex® esta correlação só passou a ocorrer a partir da lima nº40. / This study evaluated the influence of foramen diameter and endodontic instrument size on the odontometry reading of two electronic apical measuring devices. Forty mandibular incisors were used, which were divided into four groups according to the apical foramen diameter (100, 200, 300 and 400µm). After coronal opening of these teeth and access to the root canals, the root canal length was measured with aid of a clinical microscope with 7.8x magnification, from the incisal edge until the file tip reached the apical foramen. Ten teeth with 100-µm diameter were placed in individual jars containing 1% agar solution in phosphate-buffered saline, maintaining around 2/3 of their roots immersed in the solution to allow measurement with Root ZX (J. Morita, Japan) and NovApex (Forum, Israel). Teeth were measured with files n. 10 until the distance of 0.5mm from the apex was indicated by the device. Another measurement was performed on the other thirty teeth with files n. 10 and files with diameters corresponding to the foramen diameters (200µm, 300µm and 400µm). Statistical analysis was performed by two-way analysis of variance for overall comparison between the devices and employment of file n. 10 in all teeth, and Tukey test for individual comparisons. The results demonstrated statistical difference in the precision of both devices, with a more accurate result for Root ZX (p<0.05). Teeth with narrower foramina presented a more accurate measurement with the apical measuring device, and teeth with wider foramina presented larger discrepancy in the measurement. Utilization of K file n. 10 in teeth with wider foramina showed more accurate measurements compared to files with size corresponding to the foramen diameters with the Root ZX® device. With the NovApex® device, this correlation was only observed with file n. 40.

This thesis aimed to model agricultural outcomes that are important to Vermont dairy farms and their surrounding communities -- runoff, erosion, nitrogen and phosphorus losses, crop yields, and timeliness of farm operations -- under a set of possible future climates. The Agricultural Policy/Environmental eXtender (APEX) model was used for this work, and the models were calibrated using data from a project that measured most of these outcomes on a set of local farms. The model setup and calibration methodology is thoroughly documented and may be a useful starting point for others who are new to agricultural modeling. Applied to two farms growing continuous corn, the future climate simulations showed that increasing temperatures by 2 C, combined with raising total precipitation or changing the seasonality of precipitation, had little effect on any outcome. Intense rainfall has increased greatly in recent decades, so a combination of higher temperatures and more intense precipitation was also simulated. This led to more runoff, more soil loss, and more nutrient losses. While median values were only modestly increased, the 95%-ile and total losses over the simulation period increased by a larger amount (as much as 53%, depending on the site). Management practices that can reduce runoff and soil/nutrient loss exist, but their effectiveness when a higher fraction of losses occur in large events is not well known. Crop yields changed by <10% in all simulations, and in some cases increased slightly. Other studies have warned of decreases in yields because of high summer temperatures and droughts. The pilot simulations in this thesis probed only a limited range of climate parameter space, so running the models for a wider range of scenarios may illuminate the circumstances in which particularly harmful and beneficial outcomes occur. Finally, APEX can in principle calculate the delays to corn planting that are expected if climate change leads to wetter conditions in the spring. However, the models consistently predicted that only harvest operations will be delayed. The reasons for this are not well understood, and it may be a useful avenue for future work. The present work is limited in a number of ways. Chief among these are somewhat mediocre model performance, and the narrow range of farming systems and climate scenarios investigated. Statistics describing the performance of the calibrated models were poorer than anticipated, and satisfactory results could not be obtained for some nutrient loss pathways. Only two farms were modeled, in just four hypothetical future climates; results for other relevant farming systems and climates may be quite different. Nonetheless, it is hoped that this thesis serves as a useful illustration of the potential and limitations of utilizing the APEX model in this context, and that it lays the groundwork for a more extensive investigation of agricultural outcomes under climate change in Vermont.

The aim of this study was to determine the change in working length (∆WL) before and after coronal flaring and after complete rotary instrumentation as a function of canal curvature. One mesiobuccal or mesiolingual canal from each of 43 extracted molars had coronal standardization and access performed. Once the access was completed, canal preparation was accomplished using Gates Glidden drills for coronal flaring and EndoSequence files for rotary instrumentation. WLs were obtained at 3 time points: pre-instrumentation (unflared), mid-instrumentation (flared) and post-instrumentation (concluded). Measurements were made via direct visualization (DV) and the CanalPro apex locator (EM) in triplicate by a single operator with blinding across the time points. Root curvature was measured using Schneider’s technique. The change in working length was assessed using repeated-measures ANCOVA. The direct visualization measurements were statistically larger than the electronic measurements (paired t-test difference = 0.20 mm, SE = 0.037, P < .0001), although a difference this large may not be clinically important. Overall, a greater change in working length was observed in straight canals than in curved canals. This unexpected finding was attributed to the limitations of the study, specifically the confounding factor of root length. This trend was more pronounced when measured electronically than via direct visualization, especially after complete instrumentation than after coronal flaring. The overall change in working length after complete instrumentation was found to be clinically insignificant in this study. A limited amount of change in working length may be expected prior to obturation.

<p>A vast range of theoretical and empirical studies now suggests that MPAs can conserve marine biodiversity and, under some circumstances, increase fishery yields. However, despite the importance of pelagic apex predators to ecosystem function, the effectiveness of spatial management for the conservation of pelagic apex predator species is still unknown. I used fishery-dependent logbook and observer datasets to assess fishing effort and both the catch and size of pelagic apex predator species around five different MPAs. The US Hawaii-based deep-set or Atlantic pelagic longline fisheries fish the waters around these MPAs; both of these fisheries have experienced multiple management measures over time to protect species and maximize fishery yield. The MPAs selected for this study range in size, age, level of protection, and reason for establishment. I found that only two MPAs of the five appeared to be benefitting the pelagic apex predator species that I selected: the DeSoto Canyon and East Florida Coast MPAs, both in the Atlantic Ocean. The size of yellowfin tuna around the DeSoto Canyon MPA borders has increased over time, as has fishing effort. In contrast, the size of swordfish has decreased near the boundary of the East Florida Coast MPA, although the catch of swordfish has increased. The increase in catch of smaller swordfish was not a surprise because the East Florida Coast MPA was established around an area that is a nursery habitat for swordfish. These results are promising for the use of static MPAs for the conservation of pelagic apex predators, but three of the MPAs in my study did not show any indication of increased fishing effort, increased catch, or changes in pelagic apex predator size near their boundaries over time. Therefore, the characteristics of the DeSoto Canyon and East Florida Coast MPAs may provide a template for how to best design new MPAs for pelagic apex predators. Both of these MPAs were established with the specific intent of reducing pelagic apex predator bycatch, in areas where there were historically high catch rates. Both areas are relatively large (> 85,000 km2) and are also closed year-round. In combination, these characteristics may provide protection for pelagic apex predators.</p> / Dissertation

The main purpose of this thesis is the development of a new methodology of contact angle measurement called ADSA-NA (Axisymmetric Drop Shape Analysis - No Apex) that analyzes drop shape configurations with no apex. Thus ADSA-NA facilitates contact angle measurements on drops with a capillary protruding into the drop. This development is desirable because the original ADSA has some limitations for contact angle measurement, and there is a need for the improvement of the accuracy of contact angle measurement. To develop ADSA-NA, a new reference point other than the apex and a new set of optimization parameters different from those of ADSA had to be defined. The three main modules of ADSA had also to be modified; the image analysis, the numerical integration of the Laplace equation for generating theoretical curves, and the optimization procedure. It was shown that ADSA-NA significantly enhances the precision of contact angle and surface tension measurements (by at least a factor of 5) compared to those obtained from sessile drops using ADSA. Computational as well as design aspects of ADSA-NA were scrutinized in depth, well beyond the level of scrutiny in the original ADSA. On the computational side, the results obtained from one and the same drop image were compared using different gradient and non-gradient edge detection strategies and different gradient and non-gradient optimization methods. It was found that the difference between the results of different edge detection strategies is minimal. It was also found that all the optimization methods yield the same answer with eight significant figures for one and the same image. The determination of the location of the solid surface in the drop image was also further refined. On the design side, the effect of controllable experimental factors such as drop height and drop volume on the accuracy of surface tension measurement was studied. It was shown that drop height is the dominant experimental factor, and larger drop heights yield lower surface tension errors.

The main purpose of this thesis is the development of a new methodology of contact angle measurement called ADSA-NA (Axisymmetric Drop Shape Analysis - No Apex) that analyzes drop shape configurations with no apex. Thus ADSA-NA facilitates contact angle measurements on drops with a capillary protruding into the drop. This development is desirable because the original ADSA has some limitations for contact angle measurement, and there is a need for the improvement of the accuracy of contact angle measurement. To develop ADSA-NA, a new reference point other than the apex and a new set of optimization parameters different from those of ADSA had to be defined. The three main modules of ADSA had also to be modified; the image analysis, the numerical integration of the Laplace equation for generating theoretical curves, and the optimization procedure. It was shown that ADSA-NA significantly enhances the precision of contact angle and surface tension measurements (by at least a factor of 5) compared to those obtained from sessile drops using ADSA. Computational as well as design aspects of ADSA-NA were scrutinized in depth, well beyond the level of scrutiny in the original ADSA. On the computational side, the results obtained from one and the same drop image were compared using different gradient and non-gradient edge detection strategies and different gradient and non-gradient optimization methods. It was found that the difference between the results of different edge detection strategies is minimal. It was also found that all the optimization methods yield the same answer with eight significant figures for one and the same image. The determination of the location of the solid surface in the drop image was also further refined. On the design side, the effect of controllable experimental factors such as drop height and drop volume on the accuracy of surface tension measurement was studied. It was shown that drop height is the dominant experimental factor, and larger drop heights yield lower surface tension errors.

Este estudo objetivou avaliar a influência do diâmetro do forame e do instrumento endodôntico na leitura odontométrica de dois aparelhos localizadores apicais eletrônicos. Foram utilizados 40 dentes incisivos inferiores, divididos em 4 grupos, de acordo com o diâmetro do forame apical (100, 200, 300 e 400 µm). Após a abertura coronária desses dentes e o acesso aos canais radiculares, realizou-se a medição do comprimento dos mesmos com auxílio de um microscópio clínico com ampliação de 7,8X, da incisal até que a ponta da lima surgisse no forame apical. Os dentes foram colocados em potes individuais contendo solução de ágar a 1% em solução salina de fosfato tamponado, mantendo-se cerca de 2/3 de suas raízes imersas na solução para que pudesse ser feita a leitura com o Root ZX® (J.Morita, Japão) e o NovApex® (Fórum, Israel). Os mesmos foram medidos com limas nº10 até que a distância de 0,5 mm do ápice fosse acusada no display dos aparelhos. Uma outra medida foi realizada nos dentes utilizando-se lima nº10 e limas com diâmetros correspondentes ao diâmetro dos forames (200µm, 300µm e 400µm). Para a análise estatística foi empregado o teste de Análise de Variância a dois critérios para o confronto global entre os aparelhos e o emprego da lima nº10 em todos os dentes e teste de Tukey para as comparações individuais. Os resultados demonstraram diferença estatística na precisão dos dois aparelhos com um resultado mais preciso para o Root ZX® (p<0,05). Dentes com forame, de menor diâmetro, apresentaram uma medida mais precisa com o localizador apical e dentes com forame de maior diâmetro apresentaram uma maior discrepância na medida. O emprego de limas tipo K nº10 nos dentes com forames de diâmetros maiores apresentaram maior precisão na medição quando comparadas às limas coincidentes aos diâmetros dos forames para o aparelho Root ZX®. Para o NovApex® esta correlação só passou a ocorrer a partir da lima nº40. / This study evaluated the influence of foramen diameter and endodontic instrument size on the odontometry reading of two electronic apical measuring devices. Forty mandibular incisors were used, which were divided into four groups according to the apical foramen diameter (100, 200, 300 and 400µm). After coronal opening of these teeth and access to the root canals, the root canal length was measured with aid of a clinical microscope with 7.8x magnification, from the incisal edge until the file tip reached the apical foramen. Ten teeth with 100-µm diameter were placed in individual jars containing 1% agar solution in phosphate-buffered saline, maintaining around 2/3 of their roots immersed in the solution to allow measurement with Root ZX (J. Morita, Japan) and NovApex (Forum, Israel). Teeth were measured with files n. 10 until the distance of 0.5mm from the apex was indicated by the device. Another measurement was performed on the other thirty teeth with files n. 10 and files with diameters corresponding to the foramen diameters (200µm, 300µm and 400µm). Statistical analysis was performed by two-way analysis of variance for overall comparison between the devices and employment of file n. 10 in all teeth, and Tukey test for individual comparisons. The results demonstrated statistical difference in the precision of both devices, with a more accurate result for Root ZX (p<0.05). Teeth with narrower foramina presented a more accurate measurement with the apical measuring device, and teeth with wider foramina presented larger discrepancy in the measurement. Utilization of K file n. 10 in teeth with wider foramina showed more accurate measurements compared to files with size corresponding to the foramen diameters with the Root ZX® device. With the NovApex® device, this correlation was only observed with file n. 40.

Orientador: Alexandre Augusto Zaia / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-18T05:18:38Z (GMT). No. of bitstreams: 1 Silva_JulianaMeloda_D.pdf: 2719063 bytes, checksum: a82216915a2d1b38d760f9da83078fa0 (MD5) Previous issue date: 2011 / Resumo: Introdução: O objetivo desta pesquisa foi avaliar a influência do alargamento foraminal e limite de instrumentação na alteração da anatomia apical, e na capacidade de selamento após obturação. Métodos: Foram selecionadas cinquenta e cinco raízes palatinas de molares superiores de dentes humanos extraídos. Posteriormente, as amostras foram divididas em três grupos (n=15) de acordo com o comprimento de trabalho, no qual o grupo 1 foi instrumentado a 1mm aquém do forame; o grupo 2 foi instrumentado no limite do forame apical; e o grupo 3 instrumentado a 1mm além do forame. Em todos os grupos foram utilizados instrumentos rotatórios de níquel-titânio, através da utilização de três limas de calibre subsequente ao do primeiro instrumento que se ajustou no comprimento de trabalho, e a obturação foi realizada com cimento AH Plus e guta-percha. Fotomicrografias foram realizadas em microscopia eletrônica de varredura (MEV), para registro da anatomia foraminal antes da instrumentação, após a utilização de cada instrumento, após instrumentação final e após obturação. Além disso, em todos os grupos foi realizada análise pelo teste de infiltração coronária por Enterococcus faecalis, incluindo os controles positivos (n=5) e controles negativos (n=5). Resultados: Os resultados deste estudo mostraram o canal cementário preservado quando a instrumentação é realizada 1mm aquém do forame apical. No que se refere à qualidade da ampliação foraminal não houve diferença estatística entre a ampliação realizada no limite do forame e a ampliação efetuada 1mm além do forame. Quando esta ampliação foi conduzida além do forame apical, maiores foram às ocorrências de desvio foraminal, porém esses desvios não interferiram na qualidade de selamento ou infiltração bacteriana. Conclusões: A análise em microscópio eletrônico de varredura mostrou uma melhor qualidade de selamento apical para os grupos que o alargamento foraminal foi realizado. No entanto o modelo experimental de infiltração bacteriana utilizando Enterococcus faecalis não revelou diferenças entre os grupos experimentais / Abstract: Introduction: The aim of this study was to evaluate the influence of the working length and apical foramen widening on the anatomy of the apical foramen and on the sealing ability after root canal filling. Methods: Fifty-five palatal roots of maxillary molars were selected. The samples were randomly divided into three groups (n=15) according to the different working lengths. Group 1, instrumentation 1 mm short of the major foramen; group 2, instrumentation in the limit of the apical foramen; and group 3, instrumentation 1 mm beyond the foramen. All groups were prepared using nickel-titanium rotary files, the instrumentation was made by enlarging the root canal to at least three times the size of the first file that bound at the working length, and the canals were obturated with AH Plus and gutta-percha. Photomicrographs were taken using a scanning electron microscopy (SEM) before instrumentation, after instrumentation of the apical foramen with each file, and after root canal filling. Moreover, coronal bacterial microleakage with Enterococcus faecalis was performed, including positive controls (n=5) and negative controls (n=5). Results: The cemental canal was uninstrumented when the instrumentation was made 1 mm short of the major foramen. The quality of the apical foramen widening at the limit of the apical foramen and 1 mm beyond the foramen showed no statistical differences. However, instrumentation 1 mm beyond the apical foramen promoted more deviations from the original foramen anatomy, but these deviations do not affect the quality of sealing or bacterial infiltration. Conclusions: Microscopic analysis showed that both widening groups (G2 and G3) resulted in good quality apical foramen obturation. However, statistical analysis of the bacterial leakage showed no statistically significant differences between all of the groups tested / Doutorado / Endodontia / Doutor em Clínica Odontológica

nÃo hà / Os localizadores eletrÃnicos foraminais (LEFs) disponÃveis atualmente utilizam diversos mÃtodos de determinaÃÃo eletrÃnica da posiÃÃo foraminal, qual seja a medida entre o forame apical e uma referÃncia incisal/oclusal, definindo consequentemente o comprimento do canal radicular. Cada um desses mÃtodos procura oferecer maior precisÃo e menor sensibilidade a possÃveis interferÃncias no sistema de canais radiculares. Desta forma, procurou-se avaliar a precisÃo de alguns destes LEFs ex vivo e in vivo na realizaÃÃo de odontometrias eletrÃnicas em diferentes posiÃÃes (0,0 mm e -1,0 mm) e em condiÃÃes de uso clÃnico, respectivamente. No estudo ex vivo, 42 prÃ-molares inferiores tiveram seus comprimentos reais comparados a odontometrias eletrÃnicas realizadas com os LEFs Root ZX, Mini Apex Locator, Propex II, iPex e RomiApex A-15. Inicialmente, em funÃÃo dos displays dos aparelhos, determinaram-se mediÃÃes 1,0 mm aquÃm do forame apical (FA), e posteriormente as mediÃÃes no FA. Para o estudo in vivo, dez pacientes que apresentavam prÃ-molares com indicaÃÃo de exodontia como parte de seus planejamentos clÃnicos ortodÃnticos tiveram odontometrias eletrÃnicas realizadas com os LEFs Propex II e Root ZX previamente a exodontia. Os Ãltimos instrumentos utilizados foram fixados aos dentes que foram entÃo extraÃdos e tiveram 4,0 mm apicais de suas raÃzes expostos e analisados quanto à distÃncia entre as pontas dos instrumentos e os FA. No estudo ex vivo, considerando as mediÃÃes realizadas por cada um dos aparelhos a 0,0 mm e a -1,0 mm, a precisÃo dos LEFs foi: 70,6% e 47,1% (Root ZX), 61,8% e 52,9% (Mini Apex Locator), e 67,6% e 38,2% (Propex II), 61,8% e 38,2% (iPex), e 73,5% e 38,2% (RomiApex A-15), respectivamente (Â0,5 mm). DiferenÃas estatÃsticas foram encontradas para o Propex II, iPex e RomiApex A-15, quando comparadas suas leituras nas duas posiÃÃes (0,0mm X -1,0 mm). NÃo foram encontradas diferenÃas entre os LEFs a 0,0 mm, porÃm, a -1,0 mm o iPex foi estatisticamente inferior aos demais. Jà no estudo in vivo, o FA foi localizado em 75% (Root ZX) e 66,7% (Propex II), considerando margem de Â0,5 mm, tendo sido encontrada diferenÃa estatisticamente significante entre os LEFs. Diante do exposto, nas condiÃÃes do estudo, pode-se concluir que os LEFs sÃo ferramentas confiÃveis na determinaÃÃo de comprimentos reais, todavia, nÃo sÃo infalÃveis; que em condiÃÃes ex vivo, quando mantidos aquÃm do FA, todos os LEFs reduziram sua precisÃo, tendo o Propex II, iPex e RomiApex A-15 apresentado diferenÃas significantes; e que em condiÃÃes de uso clÃnico, o Root ZX apresentou maior confiabilidade do que o Propex II. / The electronic foramen locators (EFLs) currently available are based on different methods for determination of the distance between the apical foramen and a coronal reference, consequently presenting the real root canal length. Each of these methods aim to offer greater precision while presenting lower sensitivity to potential interferences found in the root canal system. With this in mind, the goal of this work was to evaluate the precision of some of these EFLs ex vivo and in vivo for electronic measurement of the root canal length at two different positions (0.0 mm and -1.0 mm) and under clinical conditions, respectively. In the ex vivo study, 42 mandibular bicuspids had their actual lengths compared to electronic measurements performed by the following EFLs: Root ZX, Mini Apex Locator, Propex II, iPex, and RomiApex A-15. Initial measurements were performed to positions identified by the devices as 1.0 mm short of the apical foramen (AF), and subsequent measurements were at the AF (0.0 mm). For the in vivo study, ten patients with bicuspids referred for extraction as part of their orthodontic clinical planning had electronic root length measurements using two EFLs, Propex II and Root ZX, prior to extraction. The last files used were fixated to the teeth, which were then extracted. Then, the apical 4 mm of the canals were exposed to allow assessment of the distance between the tip of the file and the AF. The percentages of precision from the ex vivo electronic measurements at 0.0 mm and -1.0 mm considering each device were: 70.6% and 47.1% (Root ZX); 61.8% and 52.9% (Mini Apex Locator); 67.6% and 38.2% (Propex II); 61.8% and 38.2% (iPex); and 73.5% and 38.2% (RomiApex A-15), respectively (Â0.5 mm). Statistical differences were observed for Propex II, iPex, and RomiApex A-15 when measurements at both positions were compared (0.0 mm X -1.0 mm). No significant differences between the EFLs were observed at 0. 0 mm. However, at -1.0 mm, the precision of iPex was statistically lower compared with the other devices. Regarding the in vivo study, the AF was located in 75% (Root ZX) and 66.7% of the teeth (Propex II), under a tolerance margin of Â0.5 mm. Statistically significant differences were observed between the two EFLs. Based on the results obtained and considering the conditions of this work, it was concluded that EFLs are reliable tools for determining the real length of the canal, but are not infallible. It was also observed in the ex vivo experiments that all EFLs had decreased precision in measurements with the instruments short of the AF, with significant differences observed between Propex II, iPex, and RomiApex A-15. Moreover, it was concluded that under clinical conditions, Root ZX was more reliable than Propex II.