Aim: The aim of this study was to evaluate the accuracy of the Wirele-X (Forum Tec, Ashkelon, Israel), a new Bluetooth-enabled electronic apex locator (EAL). The accuracy of the Wirele-X and the Root ZX II (J. Morita, Tokyo, Japan) was compared in vitro using an alginate model. Materials/Methods: Thirty-one extracted single-rooted human teeth with mature apices were decoronated at the CEJ. Under 10X magnification, actual canal lengths (ACL) were determined. The teeth were embedded in alginate and electronic canal length measurements were obtained using the Root ZX II and Wirele-X EALs. Each tooth was measured three times with both EALs. A blinded examiner measured each file with a digital micrometer to the nearest 0.01 mm. Differences between ACLs and the average measurements from the EALs were compared with Student's t test for related samples. Results: The average distance from the file tip to the apical foramen (AF) was -0.11 mm (±0.16) and -0.07 mm (±0.21) for the Root ZX II and Wirele-X systems, respectively. There were no statistically significant differences between the two apex locators in their ability to locate the AF (p > 0.05). Conclusions: Both the Wirele-X and the Root ZX II provided a high level of accuracy and reliability in locating the AF.

Since its commercialization, the Internet has grown exponentially. A large variety of devices can communicate creating advanced services for a diverse ecosystem of applications. However, as the number of Internet hosts has grown, the size of routing tables required to correctly route data between them has also increased exponentially. This growth rate necessitates increasingly frequent upgrades to routing device hardware, providing them with additional memory for fast-access storage of route information. These upgrades are both physically and fiscally untenable, and a new Internet routing solution is necessary for future growth. This research focuses around an incrementally deployable, reactive routing system that is scalable to projected Internet growth. It requires no hardware or software updates to Internet routers, and offoads processing to end hosts and the network's edge. Within this framework, routers can make accurate decisions about optimal data paths; incurring no increase in path length over the current routing system. A new architecture for IP Mobility is considered as a case study within this routing system, and compared with existing standards and implementations. The new architecture eliminates the triangle routing problem, while providing legacy hosts with connectivity to mobile devices. This mobility solution can integrate with a variety of hierarchical reactive routing systems with little overhead.

Automatic vehicle locator (AVL) systems, utilizing military's global positioning system, may impact response time to law enforcement calls for service. In order to evaluate the impacts of AVL on response time to calls for service at the Altamonte Springs Police Department (ASPD), computer aided dispatch (CAD) data from years 1999 to 2003 were analyzed. The analysis of each of the data sets consisted of an initial sequence chart, an analysis of variance (ANOVA), a means plot and a linear regression. Interviews of ASPD personnel were conducted to understand user perceptions of AVL. Based on the ANOVA results, trends indicate that weekly response time was significantly lower during the AVL partial implementation period than during the pre or post AVL stages across all categories of data analyzed. Based on the regression results, trends indicate that the overall impact of AVL on response time for all categories analyzed is flat and show AVL as having no overall impact on response time across all calls for service analyzed. An exception to this is the findings related to Priority 3 calls for service; however this exception can be attributed to performance during the pre AVL implementation stage. These results do not suggest a capability for AVL to reduce response time to calls for service in a meaningful comprehensive way. Thus, the study's hypotheses are not supported.

Incorporating geophysical technologies into forensic investigations has become a growing practice. Oftentimes, forensic professionals rely on basic metal detectors to assist their efforts during buried weapons searches, perhaps being used by someone with negligible or limited training, in turn slowing down investigation time and destroying the scene. This has created a need for research in the area of weapons searches, specifically to formulate guidelines for advanced geophysical methods that may be appropriate for locating weapons that have been discarded or buried by criminals attempting to conceal their involvement in a crime. This research project was the first to demonstrate the utility of geophysical technologies at a crime scene or a suspected weapon burial site by detecting and identifying specific types of buried metal targets, including an array of firearms. Controlled testing of 32 buried targets (including sixteen decommissioned street-level firearms, six pieces of assorted scrap metals, and ten blunt or bladed weapons) was conducted using a basic all-metal detector, an advanced metal detector, and a magnetic locator. Overall, a number of important conclusions were drawn from the research project. All forensic targets included in the project were detected with the basic all-metal detector, but only down to the shallower depths. The magnetic locator provided the deepest detection for the largest firearms, scrap metals, and miscellaneous weapons. However, not all forensic targets included in the project were detected due to the detection capabilities inherent to the magnetic locator (i.e. only detecting ferromagnetic items). The advanced metal detector was best suited for detecting the handguns and was able to detect most of the targets, excluding a number of items comprised of iron, down to deeper depths using the factory presets.

The aims of this study were to determine the efficacy of the KontrolFlexTM AccufileTM compared to the READY•STEEL™ Flexofile® using an electronic apex locator and to evaluate the instrument’s design via scanning electron microscopy. Actual canal lengths of thirty extracted teeth were determined under magnification. An alginate model was used to determine experimental canal lengths with the Root ZX II apex locator and size #10 Accufiles and Flexofiles. Differences between actual lengths and experimental lengths were compared with Student’s t test. The average experimental lengths were short of the actual length by -0.10 mm (±0.34) and -0.12 mm (±0.16) for the Accufile and Flexofile, respectively with no statistical difference (p > 0.05). SEM images revealed similar non-cutting “batt” tips and a square cross-section for the Accufile and triangular for the Flexofile. Both files provided similarly high levels of reliability when used with the Root ZX II electronic apex locator.

Multihoming allows nodes to be multiply connected to the network. It forms the basis of features which can improve network responsiveness and robustness; e.g. load balancing and fail-over, which can be considered as a choice between network locations. However, IP today assumes that IP addresses specify both network location and node identity. Therefore, these features must be implemented at routers. This dissertation considers an alternative based on the multihoming approach of the Identifier Locator Network Protocol (ILNP). ILNP is one of many proposals for a split between network location and node identity. However, unlike other proposals, ILNP removes the use of IP addresses as they are used today. To date, ILNP has not been implemented within an operating system stack. I produce the first implementation of ILNP in FreeBSD, based on a superset of IPv6 – ILNPv6 – and demonstrate a key feature of ILNP: multihoming as a first class function of the operating system, rather than being implemented as a routing function as it is today. To evaluate the multihoming capability, I demonstrate one important application of multihoming – load distribution – at three levels of network hierarchy including individual hosts, a singleton Site Border Router (SBR), and a novel, dynamically instantiated, distributed SBR (dSBR). For each level, I present empirical results from a hardware testbed; metrics include latency, throughput, loss and reordering. I compare performance with unmodified IPv6 and NPTv6. Finally, I evaluate the feasibility of dSBR-ILNPv6 as an alternative to existing multihoming approaches, based on measurements of the dSBR's responsiveness to changes in site connectivity. We find that multihoming can be implemented by individual hosts and/or SBRs, without requiring additional routing state as is the case today, and without any significant additional load or overhead compared to unicast IPv6.

Vasiliki Katrinaki Objektive Beurteilung diagnostischer Anästhesien von Hufgelenk, Bursa podotrochlearis und Palmarnerven bei Pferden mit Vorderhandlahmheiten und deren Ursprung in der Hufregion. Klinik für Pferde, Veterinärmedizinische Fakultät, Universität Leipzig Eingereicht Dezember 2023 Einleitung: Orthopädische Erkrankungen weisen eine hohe Prävalenz bei Pferden auf und können das Wohlbefinden sowie ihre sportliche Nutzung stark beeinträchtigen. Erkrankungen des Hufrollen-Apparates sind für etwa ein Drittel aller chronischen Lahmheiten der Vordergliedmaße beim Pferd verantwortlich. Perineurale Anästhesien (Leitungsanästhesien) werden genutzt, um den Ursprung der Lahmheit am Pferdebein zu lokalisieren. Um die Lahmheitsursache genauer eingrenzen zu können, werden intra-synoviale Strukturen innerhalb des Hufes (Hufgelenk und/oder Bursa Podotrochlearis) anästhesiert. Die subjektive Beurteilung von Bewegungsstörungen sowie die Interpretation von diagnostischen Anästhesien führt oft zu Unstimmigkeiten zwischen unterschiedlichen Beobachtern. In den letzten Jahren wurden verschiedene Systeme entwickelt, welche eine Quantifizierung der Bewegungsstörung ermöglichen. Hiermit kann die prozentuale Verbesserung der Lahmheit nach der Durchführung diagnostischer Anästhesien über die Zeit erfasst und dokumentiert werden. Eine Anwendung solcher Systeme zur objektiven Beurteilung von Hufgelenkanästhesie (HG-A) und Bursa Podotrochlearis Analgesia (BP-A) wurde bei Pferden mit Vorderhandlahmheit bis heute nicht beschrieben. Ziel: Ziel dieser Arbeit war es: I) Die zeitabhängige Verbesserung natürlich vorkommender Vorderhandlahmheiten mit Ursprung in der Hufregion, nach erfolgter HG-A und BP-A bei Pferden zu beschreiben und II) zu prüfen, ob Schmerzen, die vom Hufgelenk bzw. dem Strahlbeinapparat ausgehen, mittels Leitungsanästhesien (Tiefe Palmarnervenanästhesie (TPA) und Mittlere Palmarnervenanästhesie (MPA)) unterschieden werden können. Unter Anwendung eines auf nicht-invasiven Beschleunigungssensoren basierenden Systems (BMISS, body-mounted inertial sensor system), sollten die Veränderungen des Bewegungsmusters vor und nach Einfluss der oben genannten diagnostischen Anästhesien quantitativ und objektiv erfasst werden. Tiere, Material und Methoden: Es handelt sich um eine prospektive klinische Studie an Patienten, die aufgrund einer Vorderhandlahmeit an der Pferdeklinik, Freie Universität Berlin, zwischen 2012 und 2016 vorstellig wurden. Alle Patienten wurden an drei aufeinander folgenden Tagen subjektiv und objektiv (BMISS) anhand eines standardisierten Protokolls von derselben Person orthopädisch untersucht. Am ersten Tag wurde der Ursprung der Lahmheit mittels Leitungsanästhesie lokalisiert. Bei positiver TPA oder MPA erfolgte anschließend eine HG-A (Tag 2) sowie eine BP-A (Tag 3). Das Gangbild wurde jeweils 10 Minuten (perineurale Anästhesie) bzw. 2, 5 und 10 Minuten (intra-synoviale Anästhesie) nach Injektion des Lokalanästhetikums beurteilt. Entsprechend wurden ausschließlich Pferde in die Studie eingeschlossen, bei denen mindesten eine der perineuralen und eine der intra-synovialen Anästhesien als “deutlich positiv” gewertet wurde. Die diagnostischen Anästhesien wurden als „deutlich positiv“ gewertet, wenn mittels BMISS eine Reduzierung der Lahmheit um mindestens 70% vom Ausgangswert gemessen wurde. Ergebnisse: Das Patientenkollektiv bestand aus 23 Pferden im Alter zwischen 4 und 16 Jahren. Anhand der Ergebnisse der Leitungsanästhesien wurden die Pferde den Gruppen „TPA“ (TPA positiv, n = 16) und „MPA“ (MPA positiv, n = 7) zugeordnet. Es konnte kein signifikanter Zusammengang zwischen einer Verbesserung der Lahmheit nach perineuraler Anästhesie und HG-A bzw. BP-A festgestellt werden (p > 0,05). Innerhalb der Gruppe „TPA“ war 2 Minuten nach intra-synovialer Injektion die Anzahl der Pferde, bei denen sich eine BP-A im Vergleich zur HG-A verbesserte, signifikant höher (p = 0,02). Bei den restlichen Messzeitpunkten konnten keine signifikanten Unterschiede zwischen BP-A und HG-A innerhalb der Gruppe „TPA“ festgestellt werden (5 Minuten: p = 0,07; 10 Minuten: p = 0,1). Aufgrund der sehr kleinen Stichprobe wurden die Daten innerhalb der Gruppe „MPA“ ausschließlich deskriptiv analysiert. Bei Betrachtung der intra-synovialen Anästhesien (unabhängig von der Leitungsanästhesie), war 2 Minuten (p < 0,001) sowie 5 Minuten (p = 0,04) nach Injektion ein signifikanter Unterschied im durchschnittlichen Grad der Verbesserung der Lahmheit zwischen HG-A und BP-A deutlich. Zehn Minuten nach Injektion wurde für beide intra-synovialen Anästhesien kein bedeutender Unterschied im Bewegungsmuster gemessen (p = 0,06). Bezüglich der zeitabhängigen Verbesserung der Lahmheit unter Einfluss der verschiedenen intra-synovialen Anästhesien zeigten die Pferde nach BP-A eine signifikante Verbesserung der Lahmheit 2 Minuten nach Injektion, welche über die Zeit konstant blieb. Bei Pferden mit positiver HG-A wurde eher eine progressive Reduktion der Lahmheit beobachtet. Der Unterschied in der Verbesserung zwischen den Messzeitpunkten 2 und 10 Minuten (p = 0,04) war signifikant. Schlussfolgerungen: Perineurale Anästhesien der distalen Vordergliedmaße ermöglichen keine Differenzierung der genauen Schmerzlokalisation in der Hufregion. Intra-synoviale Anästhesien sollten in diesem Bereich sowohl 2 als auch 5 Minuten nach Injektion des Lokalanästhetikums evaluiert werden. Während nach PB-A eine schnelle und über den Zeitverlauf konstante Verbesserung der Lahmheit eintritt, ist bei der HG-A mit einer progressiven Verbesserung der Lahmheit über 10 min nach Injektion zu rechnen.:Table of contents I List of illustrations II Abbreviations III 1. Introduction..................................................................................................................1 2. Literature......................................................................................................................3 2.1. Anatomy...................................................................................................................3 2.2. Forelimb lameness...................................................................................................5 2.3. Necessity for objective gait analysis…………………………………………………....6 2.4. Objective lameness evaluation.................................................................................7 2.5. Body-mounted inertial sensor system, Lameness Locator……………………….….8 2.6. Diagnostic analgesia of the distal limb……………….…………………………….…..9 2.7. Diagnostic imaging.................................................................................................11 2.8. Therapy....................................................................................................................12 2.9. Hypotheses.............................................................................................................13 3. Publication.................................................................................................................14 4. Declaration of own portion of work in publication.....................................................23 5. Discussion..................................................................................................................24 6. Zusammenfassung.....................................................................................................34 7. Summary………………………………………………………......…………………..…....36 8. Literature....................................................................................................................38 9. Acknowledgements....................................................................................................46 / Vasiliki Katrinaki Title: Objective evaluation for analgesia of the distal interphalangeal joint, the navicular bursa and perineural analgesia in horses with naturally occurring forelimb lameness localised to the foot Department for Horses, Faculty of Veterinary Medicine, Leipzig University Submitted in December 2023 Introduction: Lameness is a very common problem in horses, and pathologies of the navicular apparatus constitute up to one-third of all chronic forelimb lameness. Despite its high occurrence, and the fact that it can severely impair the horse’s sporting career and affect their welfare, contradictory results of diagnostic analgesia are documented. The interpretation of perineural analgesia remains confusing regarding the ability of the palmar digital nerve block (PDNB) to differentiate pain coming from pathologies of the distal interphalangeal joint (DIPJ) or the navicular syndrome. Thus, the outcome and interpretation of intra-synovial diagnostic analgesia of the distal interphalangeal joint and the navicular bursa remain controversial, and no objective live over ground studies have been performed so far to establish the percentage of improvement over time from these two analgesia techniques. Aim of the study: The aim of the study was to objectively evaluate with the use of an inertial-sensor based system the qualitative and time-dependent outcome of distal interphalangeal joint analgesia (DIPJ-A) and navicular bursa analgesia (NB-A) in naturally occurring forelimb lameness and to assess if perineural analgesia of the distal limb can differentiate pain coming from the DIPJ or the navicular apparatus. Study design: Prospective clinical trial. Methods: Clinical cases with forelimb lameness were evaluated objectively using a body- mounted inertial sensor system (BMISS) at the Equine Hospital of Freie Universität Berlin, Germany between 2012 and 2016. The ages of the animals varied between four and 16 years. A three-day lameness examination was performed subjectively and objectively. The subjective evaluation was always performed by the same veterinarian during the 3 days and the objective examination was performed using the BMISS. The horses were hospitalised for the three-day lameness examination. Lameness was localised to the foot with a palmar digital nerve block and/or an abaxial sesamoidean nerve block (ASNB) at day 1, and analgesia of the DIPJ (DIPJ-A) and NB (NB-A) were performed at day 2 and 3. Improvement following perineural analgesia was measured after 10 min and intra-synovial blocks after 2, 5 and 10 min, respectively. Horses with at least 70% improvement measured objectively after diagnostic analgesia were included in the study. Results: A total of 23 cases of forelimb lameness were included in this study. The age of the horses varied between four and 16 years. The side and degree of baseline lameness remained stable during the 3 days of lameness examination. The PDNB group included horses with a positive PDNB (n=16) and the ASNB group included horses with a negative PDNB and a positive ASNB (n=7). The majority of the horses had a positive response to PDNB compared with ASNB but there was no significant association between improvement following perineural analgesia and the DIPJ-A and NB-A in the number of horses that improved after DIPJ and NB analgesia (p>0.05). Comparison between the PDNB group and intra-synovial analgesia showed that in 2 min assessments there was a statistically significant difference in the number of horses that improved with an NB-A compared to DIPJ-A (p=0.02). In 5 min and 10 min evaluations, such a result was no longer observed (p=0.07 in 5 min, p=0.1 in 10 min). Comparison of the ASNB group to intra-synovial analgesia was descriptive because the number of horses included in this group was small. The mean improvement in the lameness was different between DIPJ-A and NB-A at 2 min (p<0.001) and at 5 min (p=0.04); however, this difference was no longer observed after 10 min (p=0.06). Evaluation of intra-synovial analgesia over time showed that a positive NB-A revealed a high degree of improvement already after 2 min that remained stable, whereas the DIPJ-A improved over time showing a significant difference in mean improvement between 2 min and 10 min measurements (p=0.04). Conclusions: Our results suggest that perineural analgesia is not reliable enough to differentiate pain originating from DIPJ and NB. The DIPJ-A and the NB-A should be evaluated at 2 and 5 min, since a significant difference of lameness improvement was measured for these points of time, pointing out the necessity to perform both blocks to identify the painful region. An early evaluation of the DIPJ-A and NB-A can determine the origin of the pain. An improvement in NB-A was constant over time, whereas a progressive improvement in lameness over the 10 min after injection is to be excepted in DIPJ-A.:Table of contents I List of illustrations II Abbreviations III 1. Introduction..................................................................................................................1 2. Literature......................................................................................................................3 2.1. Anatomy...................................................................................................................3 2.2. Forelimb lameness...................................................................................................5 2.3. Necessity for objective gait analysis…………………………………………………....6 2.4. Objective lameness evaluation.................................................................................7 2.5. Body-mounted inertial sensor system, Lameness Locator……………………….….8 2.6. Diagnostic analgesia of the distal limb……………….…………………………….…..9 2.7. Diagnostic imaging.................................................................................................11 2.8. Therapy....................................................................................................................12 2.9. Hypotheses.............................................................................................................13 3. Publication.................................................................................................................14 4. Declaration of own portion of work in publication.....................................................23 5. Discussion..................................................................................................................24 6. Zusammenfassung.....................................................................................................34 7. Summary………………………………………………………......…………………..…....36 8. Literature....................................................................................................................38 9. Acknowledgements....................................................................................................46

In this bachelor thesis, cable fault locators are studied for use on the overhead electrode lines in the HVDC (High Voltage Direct Current) Light project Caprivi Link. The cable fault locators studied operates with the principle of travelling waves, where a pulse is sent in the tested conductor. The time difference is measured from the injection moment to the reflection is received. If the propagation speed of the pulse is known the distance to the fault can be calculated. This type of unit is typically referred to as a TDR (Time Domain Reflectometer). The study is performed as a computer simulation where a simplified model of a TDR unit is created and applied to an electrode line model by using PSCAD/EMTDC. Staged faults of open circuit and ground fault types are placed at three distances on the electrode line model, different parameters of the TDR units such as pulse width and pulse amplitude along with its connection to the electrode line are then studied and evaluated. The results of the simulations show that it is possible to detect faults of both open circuit and ground fault types with a suitable TDR unit. Ground faults with high resistance occurring at long distances can be hard to detect due to low reflection amplitudes from the injections. This problem can somewhat be resolved with a function that lets the user compare an old trace of a “healthy” line with the new trace. The study shows that most of the faults can be detected and a distance to the fault can be calculated within an accuracy of ± 250 m. The pulse width of the TDR needs to be at least 10 μs, preferable 20 μs to deliver high enough energy to the fault to create a detectable reflection. The pulse amplitude seams to be of less significance in this simulation, although higher pulse amplitude is likely to be more suitable in a real measurement due to the higher energy delivered to the fault. The Hipotronics TDR 1150 is a unit that fulfil these requirements and should therefore be able to work as a line fault locator on the electrode line.

Over the last few years the ASA determined KM as a priority to assist with reducing knowledge loss, realising information assets and reducing work duplication by attempting to implement IKM tools and strategies. This research employed a pragmatic viewpoint, using a mix of both quantitative and qualitative methods to check reliability, to ensure validity while undertaking the task of implementing the IKM tools. Using a case study strategy and action research was justified, as to be pragmatic the researcher needed to understand the extent of the problem within a specified context. The research discussed in this thesis, provides a new framework for implementing KM tools; focusing on the NSO category, which the case study organisation falls into. The literature agrees enlisting influential members onto the project is vital for success; however, the findings suggested that success was not only tied to this buy-in alone, but also to the organisation s ability to retain these members for the duration of the project. The research proposed the use of a newly developed tool within the new framework, as an approach to reduce the time it takes to undertake traditional social network analysis of the organisation, as it became clear that there was a need for a method of producing updated results of the SNA, which would span the length of long projects within organisations with significantly high staff turn-over rates. Privacy was given as a factor to consider the in literature; however, the findings from this study indicated that a majority of the participants were comfortable with the system. Email knowledge extraction, and email social network systems are not new concepts, however this research presents EKESNA; a novel tool that combines both concepts in a way that allows for the continuous discovery, visualisation, and analysis of knowledge networks around specified topics of interest within an organisation; linking conversations to specific expert knowledge. EKESNA s continuous discovery of the organisation s knowledge network affords members up-to-date data to inform business process reengineering. This is a potentially ground breaking new tool that has the possibility of transforming the KM landscape in NSOs as well as a whole range of other kinds of enterprises.

Este trabalho teve como objetivo avaliar a influência da espessura de dentina radicular apical, da constrição apical e do diâmetro do forame apical na precisão de leituras realizadas com os localizadores foraminais eletrônicos Mini Apex Locator e Root ZX II®. Foram utilizados 30 incisivos inferiores permanentes unirradiculados de humanos, extraídos, com raízes íntegras e ápices completamente formados e portadores de um único canal. Por meio de um paquímetro, as espessuras radiculares dos dentes foram medidas, no sentido mésio-distal a 1,0 e a 4,0mm aquém do forame apical. Após a abertura coronária, uma lima tipo K no 10, munida de limitador de penetração, foi introduzida no canal radicular até que sua extremidade pudesse ser visualizada na altura do forame, com o auxílio de um microscópio óptico com aumento de 7,8X. Dessa medida, subtraiu-se 1,0mm, estabelecendo-se o comprimento de trabalho. A dilatação do canal radicular foi feita, inicialmente, com brocas de Gates Glidden, em ordem numérica decrescente, da número 5 até a número1, até 4,0mm aquém do forame apical. Os dentes foram fixados em um modelo experimental especialmente desenvolvido para permitir a medição com os localizadores foraminais eletrônicos. Tal modelo era constituído por dois segmentos de PVC: um de menor calibre, com diâmetro correspondente a meia polegada por 2,0cm de comprimento, com as duas extremidades abertas e outro, de maior calibre, com uma das extremidades fechada e com diâmetro interno equivalente ao diâmetro externo do primeiro segmento (3/4 de polegada). No segmento de maior diâmetro, foi feito um orifício lateral que permitiu o posicionamento do eletrodo labial do localizador foraminal eletrônico e, para a medição, no seu interior, foi colocado alginato e, então, encaixado o componente de menor diâmetro, fazendo com que o ápice radicular ficasse imerso no alginato. Foram realizadas as leituras com os localizadores, iniciando-se com a lima tipo K no 10 e seguindo-se a seqüência de instrumentação e medida até a lima tipo K no 130; a lima tipo K no 10 foi utilizada em todos os diâmetros. Terminada essa fase, os dentes tiveram os canais sobreinstrumentados, isto é, a ponta da lima ultrapassou o forame apical em 1,0mm, a partir da lima tipo K no 25 e seguindo até a lima tipo K no 130; novas medidas foram obtidas com cada lima que sobreinstrumentou o forame e a lima no 10 foi utilizada em todos os diâmetros. Em todos os casos o canal radicular estava preenchido com hipoclorito de sódio a 1%. Para a análise estatística foram empregados os testes de Análise de Variância a dois critérios e de Tukey. Os resultados indicaram que as variáveis capazes de influenciar a recisão das leituras com os localizadores foraminais eletrônicos foram a eliminação da constrição apical com o consequente aumento do diâmetro do forame apical, ao contrário da espessura da parede dentinária do canal radicular, que não interferiu significativamente na precisão das leituras. / This study evaluated the influence of the apical root dentin thickness, apical constriction and diameter of the apical foramen in the accuracy of readings obtained using the electronic apex locators Mini Apex Locator and Root ZX II ®. The study was conducted on 30 extracted human single-rooted permanent mandibular incisors, with intact and completely formed roots and presenting a single canal. The root thickness of the teeth was measured with a pachymeter in mesiodistal direction, at 1.0 and 4.0mm from the apical foramen. After coronal opening, a 10 K file with a stop was introduced in the root canal until its end could be observed at the level of the apical foramen, with aid of a light microscope with 7.8X magnification. One millimeter was subtracted from this measurement for establishment of the working length. Enlargement of the root canal was initially performed using Gates Glidden burs, in decreasing order, from number 5 to number 1, up to 4.0mm beyond the apical foramen. The teeth were fixated in an experimental model especially designed to allow the measurement with the electronic apex locators. This model was composed of two PVC segments: one smaller, with diameter corresponding to half inch with 2.0cm length, with both ends open; and the other, with larger diameter, with one end closed and internal diameter similar to the external diameter of the first segment (3/4 inch). In the segment with greater diameter, a lateral orifice was made to allow positioning of the lip electrode of the electronic apex locator. For the measurement, alginate was poured and the component with smaller diameter was fitted, so as the root apex was immersed in alginate. Readings were performed using the electronic apex locators, initiating with a 10 K file and following the sequence of instrumentation and measurement up to 130 K file. The 10 K file was used in all diameters. After this stage, the root canals were overinstrumented, i.e. the file tip was introduced until 1.0mm beyond the apical foramen, beginning with 25 K file up to 130 K file; new measurements were obtained with each file overinstrumenting the apical foramen, and the 10 K file was used in all diameters. In all cases, the root canal was irrigated with 1% sodium hypochlorite. Statistical analysis was performed by two-way analysis of variance and the Tukey test. The results indicated that the variables that may influence the accuracy of readings with the electronic apex locators were the elimination of apical constriction with consequent increase in the diameter of the apical foramen, different from the thickness of the root canal dentinal wall, which did not significantly influence the accuracy of readings.