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El uso de la Tomografía Computarizada de Haz Cónico (CBCT) ha sido ampliamente relevante en el campo de la Endodoncia, pues además de que permite la visualización en los diferentes cortes (axial, coronal y sagital), facilita la emisión de diagnósticos más precisos como fracturas radiculares y/o coronales, reabsorciones radiculares, periodontitis apical en estadios iniciales, perforaciones, planificación de cirugías endodónticas, entre otros. Objetivo: Determinar la sensibilidad y especificidad de la CBCT en la detección de fractura vertical mediante la revisión sistemática. Métodos: Se realizó una revisión sistemática, en la cual se tuvieron en cuenta estudios realizados entre los años 2012 a 2022. Se utilizaron las bases de datos Pubmed y Springer, incluyendo artículos en inglés y español disponibles en forma completa. Se utilizaron artículos relacionados con Efectividad y sensibilidad de la CBCT en los hallazgos de fractura vertical. Resultados: En esta revisión se identificaron 176 documentos. Luego de revisar los títulos, resúmenes y palabras clave, se descartaron 78, pues no trataban sobre Efectividad y Sensibilidad de la CBCT o estaban duplicados. De estos se descargaron 108 artículos para ser examinados con mayor profundidad por medio de la lectura del texto completo, de los cuales se descartaron 87 debido a que no eran estudios in vivo, in vitro o por no estar dentro del rango de año de publicación establecido. Finalmente, el número de artículos de texto completo evaluados para su elegibilidad fueron 21. Conclusiones: El uso de CBCT en el diagnóstico de fractura vertical es una herramienta útil, pero se debe tener conocimiento de la configuración del equipo para poder ser lo más preciso posible, utilizar tamaños de voxel menores a 2 micras, para evitar la pérdida de sensibilidad y especificidad. The use of Cone Beam Computed Tomography (CBCT) has been very relevant in the field of Endodontics, since in addition to allowing visualization in different cuts (axial, coronal and sagittal), it facilitates the issuance of more precise diagnoses such as root and/or crown fractures, root resorptions, apical periodontitis in early stages, perforations, endodontic surgery planning, among others. Objective: To determine the sensitivity and specificity of CBCT in the detection of vertical fracture through systematic review. Methods: A systematic review was carried out, in which studies carried out between the years 2012 and 2022 were taken into account. The Pubmed and Springer databases were used, including articles in English and Spanish available in full. Articles related to the Effectiveness and Sensitivity of CBCT in the findings of vertical fracture were used. Results: In this review, 176 documents were identified. After reviewing the titles, abstracts and keywords, 78 were discarded, since they were not analyzed on the Effectiveness and Sensitivity of the CBCT or they were duplicated. Of these articles, 108 were downloaded to be examined in greater depth by reading the full text, of which 87 were discarded because they were not in vivo or in vitro studies or because they were not within the established publication year range. . Finally, the number of full-text articles evaluated for eligibility was 21. Conclusions: The use of CBCT in the diagnosis of vertical fracture is a useful tool, but knowledge of the equipment configuration must be known in order to be as accurate as possible. , use a voxel size smaller than 2 microns, to avoid loss of sensitivity and specificity. Especialista en Endodoncia http://www.ustabuca.edu.co/ustabmanga/presentacion Especialización

We have studied by classic anatomical methods the presumed cranium of Sampiero Corso (1498-1567), who was the first Corsican nationalist. This cranium corresponds to that of a male individual, aged at least of 50 years ; there are many similarities between the cranium face and the one that corresponds to his portrait. The vertical fracture, observed on the cranium left side of the forehead, corresponds probably to the stab sword that caused Sampiero Corso’s death. The 14C radiodating of a bone fragment located at the cranium basis gives a calendar 1450-1510 years interval (at 95% of probability) of age.

Hydraulic fracturing, as a key technology of deep energy exploitation, accelerates the rapid development of the modern petroleum industry. To study the mechanisms of hydraulic fracture propagation and rock failure mode of the vertical well hydraulic fracturing, the true triaxial hydraulic fracturing test and numerical simulation are carried out, and the influence of the principal stress difference, water injection displacement, perforation angle and natural fracture on fracture propagation is analyzed. The results show that the fracture propagation mode of limestone is mainly divided into two types: the single vertical fracture and the transverse-longitudinal crossed complex fracture. Under high displacement, the fracturing pressure is larger, and the secondary fracture is more likely to occur, while variable displacement loading is more likely to induce fracture network. Meanwhile, the amplitude of acoustic emission (AE) waveform of limestone during fracturing is between 0.01 and 0.02 mV, and the main frequency is maintained in the range of 230–300 kHz. When perforation angle θ=45°, it is easy to produce the T-type fracture that connects with the natural fracture, while X-type cracks are generated when 0=30°. The results can be used as a reference for further study on the mechanism of limestone hydraulic fracturing.

Gravity displacement often occurs when drilling a vertical fractured formation, causing a downhole complexity with risk of blowout and reservoir damage, well control difficulty, drilling cycle prolongation, and increased costs. Based on an experimental device created for simulating the gravity displacement, various factors affecting the displacement quantity were quantitatively evaluated by simulating the fracture width, asphalt viscosity, drilling fluid density, and viscosity under different working conditions, and a liquid–liquid displacement law was obtained. Using the theories of rock mechanics, fluid mechanics, and seepage mechanics, based on conformal mapping, as well as a fracture-pore double substrate fluid flow model, we established a steady-state mathematical model of fractured formation liquid–liquid gravity displacement by optimizing the shape factors and using a combination of gravity displacement experiments to verify the feasibility of the mathematical model. We analyzed the influence of drilling fluid density, fracture height and length, and asphalt viscosity on displacement rate, and obtained the corresponding laws. The results show that when the oil–fluid interface is stable, the fracture width is the most important factor affecting the gravity displacement, and plugging is the most effective means of managing gravity displacement.

Objectives: Condyle fractures constitute 17.5–52% of all mandibular fractures. Our first aim was to investigate whether panoramic radiography or LSP images with lower radiation dose can be used instead of CBCT in the diagnosis of vertical condylar fractures. The second aim of the study was to compare observers' capabilities in diagnosing these fractures. Materials and Methods: A sample consisting of 15 fresh cadaver mandibles with 30 condyles frozen within 24 hours post-mortem was randomly selected. Vertical fractures from the lateral 2/3 of the condyle head with 0.5 (10 condyles) and 1mm (10 condyles) thickness were created using a fret saw. After creating condyle fractures, digital panoramic, LSP, and CBCT images were acquired. Two dentomaxillofacial radiologists with 15 years of experience, two dentomaxillofacial radiologists with five and seven years of experience, and two newly graduated dentists have evaluated the images. The success of the observers in diagnosing the vertical condyle fracture in each imaging method, intra-observer and inter-observer agreement was evaluated. Results: The success of all dentists in determining the condyle fractures using LSP images was higher than the success they achieved using panoramic images, but it was not sufficient. Using different imaging options with CBCT, all diagnoses made by new graduates and dentomaxillofacial radiologists with five and 15 years’ experience were 100% compatible with the gold standard (AC1: 1 (1–1)). Conclusions: For the diagnosis of vertical condyle fractures, conventional techniques (panoramic and lateral jaw imaging methods) were found to be insufficient.

The purpose of this paper is to provide scientific basis for the stability evaluation of overburden rock of repeated mining goaf under the expressway. The objectives of the present study are to reveal the development of overburden rock fractures under repeated mining and to identify the fractal characteristics of the overburden rock fractures. The results show that (1) the separation fracture and vertical fracture fissure are developed in the overburden rock under repeated mining; (2) after the mining of the lower coal seam, the fractures developed in the overburden rock of the goaf are obviously retained in general. The number of fractures on both sides of the goaf is relatively large, while in the central part, it is relatively small and the fractures in most areas are basically closed; (3) under the same advancing length of working face in the lower coal seam, the fractal dimension in the caving zone is larger than that of the fractured zone; (4) with the increase of the advancing length of working face in the lower coal seam, the variation trend of the fractal dimension appears from small to large and then to small and stable; (5) when the repeated mining is over and the overburden rock movement is basically stable, the ratio of the fractal dimension in the caving zone and the fractured zone is 1.067:1. The results have an important reference value for ensuring the safety of the expressways above the repeated mining goaf in Shanxi region and similar areas.

Solute transport in a single vertical fracture (SVF) cannot be reliably described by the classical advection-dispersion equation (ADE) model, due to the heterogeneity nature of fracture. This study conducted a group of experiments to investigate chloride ion transport in the SVFs under different rough-walled conditions, and then applied a time fractional advection-dispersion equation (F-ADE) model to offer an accurate description. A comparison between F-ADE model and a classical ADE model in describing experimental data, was also carried out. Results show that the FADE model is better than the ADE model in describing the breakthrough curve and heavy-tail phenomenon of solute transport in the fracture. Especially in the experiments with lower flow rate and higher roughness fracture, the FADE model can offer a better description for non-Fickian transport, indicating that it is a promising tool for characterizing solute transport heterogeneous vertical fracture.

This paper evaluates the axial compressive behaviour of concrete stub columns confined by steel tubes (CSC-CSTs) at low temperatures of 30 ~ −80 °C relevant to cold regions. Experiments including ten circular and ten square CSC-CSTs subjected to axial compression at four low temperatures were carried out. The studied parameters included low temperature (T), different grades of NWC (fc), wall-thickness of the steel tube (t), and height of the CSC-CSTs (L). The test results revealed that bulge of steel tubes, concrete crushing, and vertical fracture in steel tube (only in square CSC-CSTs) occurred to CSC-CSTs. The load-shortening (P S) behaviour of CSC-CSTs exhibits similar manner in the first elastic and nonlinear working stage, but varies at their recession stages due to different confinement ratio by steel tube. Low temperatures improved axial compressive behaviours of CSC-CSTs. Increasing concrete strength improved the compressive strength of CSC-CSTs at low temperatures, but reduced their ductility. Thicker steel tube improved the P S behaviour of CSCCSTs at low temperatures whilst the height of CSC-CSTs exhibited marginal influences on their low-temperature compressive behaviours. Theoretical models were developed to estimate P S behaviours of CSC-CSTs, and validations against 20 test results confirmed their accuracy.

The instability of polymeric membranes with nano- and micro-sized apertures has been regarded as one of the main reasons behind realizing ultra-thin membranes with apertures. As is well known, when the thickness of the membrane gets thinner or the aperture size gets smaller, the possibility of geometrical deformation or structural damage by collapse or fracture increases. Herein, we suggest the design rules for the stability of polymeric membranes possessing 1D nano-line patterns monolithically constructed on micro-aperture supporting layers. The proposed theoretical model, which has been thoroughly demonstrated and analyzed based on both theoretical and experimental approaches, provides stability criteria for lateral collapse and vertical fracture of ultra-thin membranes with apertures.

Objectives: The aim of this study was to evaluate the forces required to fracture roots obturated with different calcium silicate – based materials, after applying a fractured instrument removal simulation. Material and Methods: Seventy-five mandibular premolars were selected and decoronated. Then, all root canals were instrumented using Reciproc system. To mimic the root canal anatomy after the removal of a fractured instrument, each canal was enlarged with a size-3 Peeso reamer. The specimens were distributed into experimental groups according to the materials used for the root fortification: G1: Negative control, G2: ProRoot MTA, G3: Ortho MTA, G4: Biodentine, G5: Endocem MTA. Then, the teeth were embedded into acrylic blocks. A vertical fracture test was applied, and the fracture loads were recorded. Statistical interpretations were made (α=0.05). Results: G2, G3, G4, and G5 showed greater fracture resistances than G1 (P0.05). Conclusions: Any of the tested materials could be chosen to reinforce the root after the removal of a fractured instrument.

The two proposed conceptual models explaining partially saturated flow from soil into fractured rock in the intermediate fractured vadose zone have not been confirmed due to the difficulty involved in observing the soil–rock interface in situ. To address that challenge, this paper presents a series of newly developed physical experiments using a geotechnical centrifuge model of sand overlying a single dry clean smooth vertical fracture. The model shows the development of a perched water system and a saturated wetting front that progresses transversely along the interface, while breaching through the interface occurs via multiple point sources. The dominant flow mechanisms within the fracture comprise droplets, discontinuous rivulets with droplet formation, and continuous rivulets. A maximum drainage area of 30% of the width of the fracture contributes to the flow in the model, and this drainage area decreases with depth due to the merging of oscillating rivulets in the upper regions of the fracture. The presence of evidence supporting both conceptual models shows that a combined conceptual model is required to accurately explain partially saturated flow at the soil–rock interface.

The aim of the present study was to determine the vertical root fracture (VRF) resistance of roots obturated with TotalFill BC Sealer and AH Plus sealer using lateral condensation and single cone techniques in comparison to untreated controls. Sixty single rooted mandibular premolars were sectioned and divided into six groups. Ten teeth were left untreated (positive control-Gp 1) and fifty teeth were cleaned and shaped. Ten root specimens were left unfilled (negative control-Gp 2) and the remaining roots were divided into 4 groups. Gp 3, GP and AH Plus sealer (AH Plus) using the cold lateral compaction (LC) technique, Gp 4, GP and AH Plus using the Single Cone (SC) technique, Gp 5: TotalFill GP and TotalFill BC sealer using the LC technique, Gp 6: TotalFill GP and TotalFill BC sealer with SC. VRF was performed for all specimens using a universal testing machine. Analysis of variance (ANOVA) and Tukeys post-hoc multiple comparison test was used to compare the means among tested study groups. Group 1 (positive control) displayed the highest fracture resistance (946.61 ± 166.465 N), however, the lowest fracture strength was demonstrated by the specimens in group 2 (negative control) (433.31 ± 129.350 N). Specimens treated with AH plus using different obturation techniques (group 3 and 4) showed comparable outcomes (p &gt, 0.05). Similarly, specimens treated with TotalFill BC sealer with different obturation techniques showed statistically similar outcomes (p &gt, 0.05). It was also observed that specimens in groups 3, 4, 5 and 6 demonstrated comparable outcomes of fracture strength (p &gt, 0.05). The use of TotalFill-BC sealer showed similar vertical root fracture resistance as AH plus sealer in root canal treated teeth. Use of total fill-BC and AH Plus sealer in root canal treatment showed vertical root fracture resistance comparable to untreated natural teeth (positive controls).

Osteoporotic spinal fractures are seen above previous spinal instrumentation and also found in patients with diffuse idiopathic spondylotic hyperostosis (DISH). In both situations, there is marked spinal rigidity with a limited mobile spinal section that is vulnerable to motion and subsequent fracture with no or minimal trauma especially when there is concurrent osteoporosis. This is an unusual case where the patient developed a vertical anterior avulsion type fracture of T12 through a large bridging spondylotic ventral spur of bone, resulting in severe positional pain above a previous lumbar instrumented fusion. While being managed conservatively with bracing, sequential follow-up magnetic resonance imaging (MRI) and computed tomography (CT) scans showed progressive development of vacuum changes, both in the linear fracture and the adjacent intra-discal space. Vacuum changes are a strong radiologic sign of spinal instability. Because of age and not wanting to undergo further extensive fusion, he was treated with intra-discal and transpedicular placement of bone cement with the resolution of his pain.

In fractured reservoirs characterized by low matrix permeability, fracture networks control the main fluid flow paths. However, in layered reservoirs, the vertical extension of fractures is often restricted to single layers. In this study, we explored the effect of changing marl/shale thickness on fracture extension using comprehensive field data and numerical modeling.The field data were sampled from coastal exposures of Liassic limestone-marl/shale alternations in Wales and Somerset (Bristol Channel Basin, UK). The vertical fracture traces of more than 4000 fractures were mapped in detail. Six sections were selected to represent a variety of layer thicknesses. Besides the field data also thin sections were analyzed. Numerical models of fracture extension in a two-layer limestone-marl system were based on field data and laboratory measurements of Young's moduli. The modeled principal stress magnitude σ3 along the lithological contact was used as an indication for fracture extension through marls. Field data exhibit good correlation (R2 = 0.76) between fracture extension and marl thickness, the thicker the marl layer the fewer fractures propagate through. The model results show that almost no tensile stress reaches the top of the marl layer when the marls are thicker than 30 cm. For marls that are less than 20 cm, the propagation of stress is more dependent on the stiffness of the marls. The higher the contrast between limestone and marl stiffness the lower the stress that is transmitted into the marl layer. In both model experiments and field data the critical marl thickness for fracture extension is ca. 15–20 cm.This quantification of critical marl thicknesses can be used to improve predictions of fracture networks and permeability in layered rocks. Up- or downsampling methods often ignore spatially continuous impermeable layers with thicknesses that are under the detection limit of seismic data. However, ignoring these layers can lead to overestimates of the overall permeability. Therefore, the understanding of how fractures propagate and terminate through impermeable layers will help to improve the characterization of conventional reservoirs. Keywords: Boundary element modelling, Marl/limestone multilayer, Layer thickness and stiffness control, Permeability, Fractured reservoirs

The pressure records of an interference test on a huge hydraulic fracture in a layered sedimentary rock formation of the Northwest German Basin were analysed in order to determine fracture transmissivity and fracture storage coefficient. The fracture had been created by injecting some 20,000 m3 of freshwater at 3800 m depth in borehole Horstberg Z1 of the geothermal research project GeneSys. Its main purpose is to study the hydraulic properties and mechanical behaviour of artificial fractures kept open by the so called self-propping effect which results from the misfit of the opposite fracture surfaces being sheared during fracture propagation. A diagnosis of the pressure records of the interference test showed that the flow geometry is parallel (vertical linear fracture flow) rather than radial or bilinear. This is explained by assuming a highly conductive flow channel within the fracture resulting from a turn of tensile to mixed-mode fracture propagation. Based on this observation an analytical 1D-model was developed that describes transient fluid-flow in a vertical fracture that is imbedded in impermeable rock and is vertically confined by permeable rock layers. This model was verified by a corresponding 1D-numerical model and was then used to fit the observed pressure records of the constant rate interference test. The fitting procedure yielded a transmissivity of the self-propped fracture in claystone that is more than ten times lower than the transmissivity of self-propped fractures in granite as observed in HDR/EGS systems (Hot-Dry-Rock/Enhanced Geothermal Systems). At the same time it is more than ten times higher than the transmissivity of propped fractures in shale gas reservoirs. The injectivity index of the studied fracture resulting from transmissivity and the high length to height ratio of the fracture enables to circulate water or brine through the fracture at flow rates up to about 0.005 m3/s. For the given temperature of about 150°C this would satisfy the heat demand of small to medium size building complexes. Higher flow rates and heat production could be achieved with multiple fractures of this kind. The results obtained in borehole Horstberg Z1 are promising but more in-situ experiments in various rock formations and different stress regimes are necessary to generalize the results.

Characterizing subsurface fractures is a key to developing hydrocarbon and geothermal fields, as well as providing fundamental information on fracture system relevant to regional seismotectonics. Seismic characterization of fractures has generally been based on the effective medium theory, which considers seismically invisible small fractures. Therefore, there is a considerable scale gap between the fracture properties obtained by seismic methods and those from borehole logging. Recent studies of single-well reflection imaging using acoustic borehole logging data show the potential of filling the scale gap by providing fracture properties around the borehole up to a few tens of meter away from the borehole location. In the context of reflection imaging of individual fractures, in this study, we develop least-squares migration (LSM) coupled with linear-slip model. LSM solves the linearized waveform inversion to provide high-resolution quantitative images. Linear-slip model can describe wave reflection at a fracture accurately. We show numerical modelling examples of the proposed approach considering a vertical fracture with coupling compliances, and acoustic dipole measurements of a dipping fracture embedded in a background random velocity distribution. The results show that the proposed LSM provides higher resolution images than reverse-time migration, and more accurate images than the conventional LSM without linear-slip model.

This paper first describes a mathematical model of a vertical fracture with constant conductivity in three crossflow rectangular layers. Then, three forms of vertical fracture (linear, logarithmic, and exponential variations) with varying conductivity are introduced to this mathematical model. A novel mathematical model and its semi-analytical solution of a vertical fracture with varying conductivity intercepting a three-separate-layered crossflow reservoir is developed and executed. Results show that the transient pressures are divided into three stages: the linear-flow phase, the medium unsteady-flow stage, and the later pseudo-steady-flow phase. The parameters of the fracture, reservoir, and the multi-permeability medium directly influence the direction, transition, and shape of the transient pressure. Meanwhile, the fracture conductivity is higher near the well bottom and is smaller at the tip of the fracture for the varying conductivity. Therefore, there are many more differences between varying conductivity and constant conductivity. Varying conductivity can correctly reflect the flow characteristics of a vertical fractured well during well-test analysis.

The roughness of fractures may play an important role in affecting the migration and placement of proppants during hydraulic fracturing operations. A series of proppant flow experiments were conducted in attempt to compare the proppant transport mechanisms in rough fractures against those in smooth fractures. We examine the migration of proppants in rough and vertical fractures and then quantitatively reveal the effect of roughness on the instantaneous proppants transport and final proppants placement. The proppants-transport behavior in the rough and vertical fractures was observed to be totally different from that in the smooth and vertical fractures. The proppants in a rough vertical fracture do not progress like the regular sand bank that commonly occurs in the smooth fracture, but rather as an irregular-shape sand cluster with fractal characteristics. In the rough and vertical fracture, the phenomenon of proppants bridging is visually observed. The roughness of the fracture model not only affects how much of the fracture area is being occupied by the proppants, but also affects how tightly the proppants fill up the fracture.

Injection of cold water into fracture zones in Enhanced Geothermal Systems (EGS) induces contractive thermo-elastic strains in the host rock, locally altering the stress state of the reservoir. Building on previous studies with horizontal fractures we examined how such thermo-elastic effects act during injection and production from a doublet intersecting a vertically extensive fracture zone embedded in impermeable host rock with a vertical geothermal gradient and with vertical aperture variations in response to stress increase with depth. As in horizontal fracture zones, contractive strains propagate outward from point of injection of cold water and are surrounded, due to stress re-distribution, by a ring zone with increased effective normal stress and, therefore, reduced aperture. The reduced aperture ring affects production temperature evolution to different degrees: for fracture zones with initially homogeneous transmissivity the effect on temperature decline is most pronounced for injection in the deeper well while it is small to negligible for injection in the shallower well. Fractures zones with initially heterogeneous transmissivity distribution experience highly channelized flow and the enhanced normal stresses develop preferentially at the sides of the channels, having little effect on flow along the channel and temperature decline. The effects show systematic variation with the rock's Young's modulus as does the tendency to induce shear failure by thermo-elastic effects. The simulated temperature evolutions deviate significantly from previous models that assessed the economics of EGS with sub-horizontal wells intersecting vertically extensive fractures in which the geothermal gradient and thermo-mechanical were not included.

Mechanical testing based on ISO 14801 standard is generally used to evaluate the performance of the dental implant system according to material and design changes. However, the test method is difficult to reflect on the clinical environment because the ISO 14801 standard does not take into account the various loads from different directions during chewing motion. In addition, the fracture pattern of the implant system can occur both in the horizontal and the vertical directions. Therefore, the purpose of this study was to compare fatigue characteristics and fracture patterns between single directional loading conditions based on the ISO 14801 standard and multi-directional loading condition. Firstly, the static test was performed on five specimens to derive the fatigue load, and the fatigue load was chosen as 40% of the maximum load measured in the static test. Subsequently, the fatigue test was performed considering the single axial/occlusal (AO), AO with facial/lingual (AOFL) and AO with mesial/distal (AOMD) directions, and five specimens were used for each fatigue loading modes. In order to analyze the fatigue characteristics, the fatigue cycle at the time of specimen fracture and displacement change of the specimen every 500 cycles were measured. Field emission scanning electron microscopy (FE-SEM) was used to analyze the fracture patterns and the fracture surface. Compared to the AO group, the fatigue cycle of the AOFL and AOMD groups showed lower about five times, while the displacement gradually increased with every 500 cycles. From FE-SEM results, there were no different surface morphology characteristics among three groups. However, the AOMD group showed a vertical slip band. Therefore, our results suggest that the multi-directional loading mode under the worst-case environment can reproduce the vertical fracture pattern in the clinical situation and may be essential to reflect on the dental implant design including connection types and surface treatments.

Special T-type fractures can be formed when coal is hydraulically fractured and there is currently no relevant theoretical model to calculate and describe them. This paper first establishes the height calculation model of vertical fractures in multi-layered formations and deduces the stress intensity factor (SIF) at the upper and lower sides of the fracture in the process of vertical fracture extension. Combined with the fracture tip stress analysis method of fracture mechanics theory, the horizontal bedding is taken into account for tensile and shear failure, and the critical mechanical conditions for the formation of horizontal fracture in coal are obtained. Finally, the model of T-type fracture in coal fracturing is established, and it is verified by fracturing simulation experiments. The model calculation result shows that the increase of vertical fracture height facilitates the increase of horizontal fracture length. The fracture toughness of coal has a significant influence on the length of horizontal fracture and there is a threshold. When the fracture toughness is less than the threshold, the length of horizontal fracture remains unchanged, otherwise, the length of horizontal fracture increases rapidly with the increase of fracture toughness. When the shear strength of the interface between the coalbed and the interlayer increases, the length of the horizontal fracture of the T-type fracture rapidly decreases.

Specialists in the dental field often get habituated to having a partial or biased assessment of clinical findings or disorders by virtue of practicing a niche speciality over long periods of time. This can lead to a disadvantage to the patient in terms of prognosis unless a wider and all encompassing prespective is inculcated and maintained. Often in the field of endodontics, a patient presents with a finding which leads to a terminal conclusion of extraction. However, with an aim of preserving the tooth, if various principles of treatment modalities of other branches of dentistry are employed, the prognosis can take a 360° turn for successful preservation of the tooth in the arch in complete functional state. We present one such case of an incomplete vertical fracture in the furcation area of a mandibular molar, destined for extraction, but conserved with concomitant orthodontic banding followed by intentional surgical bicuspidisation and full coverage restoration.

Despite timely and appropriate management, displaced femoral neck fractures are often devastating injuries for the young patient. The risk of negative sequelae is further amplified with increasing displacement and vertical fracture patterns. Open anatomic reduction with rigid internal fixation is essential to maximize the healing potential in displaced fractures of the femoral neck. Successful primary osteosynthesis of significantly displaced femoral neck fractures in the young patient has been reported in the literature. We present a unique case of open reduction and internal fixation of a high-energy femoral neck fracture with extrusion of the head through the obturator foramen into the pelvis without associated acetabular or pelvic injury.

The aim of this study was to report two cases of orthodontic extrusion performed prior to dental implant placement. The first one reports the case of a 57 year-old-female who presented internal root resorption in the left central incisor, and orthodontic extrusion of this element was indicated. The treatment lasted 24 weeks. At the end of this period, the dental implant was placed. The second clinical event refers to a patient of 66 years of age who had vertical fracture in the left central incisor. In this case, the orthodontic extrusion was conducted in 12 weeks. At the end of this period, the dental implant was placed and also the temporary crown, but without occlusal contact. Both cases reported consisted of the involvement of the left central incisor in the aesthetic area and low bone density. The cases reported demonstrated that orthodontic extrusion is a viable alternative to the aesthetic and functional reconstruction with prosthesis over dental implants.

Cap-rock integrity is of paramount importance during injection and subsequent long-term storage of CO2 in the subsurface. Preexisting (natural) and man-induced fractures in the cap rock represent potential flow paths out of the storage formation. In this study, a first-order semi-analytical model of flow through a vertical fracture penetrating cap rock is constructed taking the stressdependent fracture permeability into account. The model is then applied to study the effects of in-situ stress normal to fracture on the flow rate through the fracture. The flow rate increases nonlinearly with the reservoir pressure, which is due to a combined effect of nonlinear fracture deformation law and the cubic law governing the flow rate.

In this paper we study the pressure drop in a hydraulic fracture after shut-in of a water injection well. The pressure transient behavior depends on fracture closure, lateral stress, rock elasticity and fracture fluid leak-off. Under the assumption that horizontal cross-sections of a vertical fracture do not depend on the vertical variable, we formulate a mathematical model which allows for determination of both pore pressure and elastic rock displacements jointly with the fracture aperture and fracture fluid pressure. An analytical consideration is performed for the case of an ideal very long fracture with the same aperture along its full length. In the general case, fracture closure is analyzed numerically.

Las fracturas del atlas son infrecuentes y representan entre el 1 al 2% de todas las fracturas vertebrales. Anatómicamente el atlas está protegido por el occipucio y las estructuras ligamentosas. Por presentar una forma en anillo, es inusual observar una fractura unilateral. Presentamos el caso de un paciente de 25 años quien presento politraumatismo y a quien se le realizo el diagnostico de fractura vertical de atlas recibiendo manejo conservador. Hacemos una revisión de la literatura de los casos publicados hasta la fecha.

Objective: The objective is to compare the vertical fracture resistance of teeth obturated with four different obturating techniques using universal testing machine (UTM). Materials and Methods: One hundred single-rooted mandibular premolars were instrumented with ProTaper Universal rotary files up to size F3. Samples were obturated using four different methods of obturation (Lateral compaction, continuous wave condensation (CWC), GuttaFlow 2, and GuttaCore). UTM was used for the evaluation of fracture resistance. Data were analyzed by one-way ANOVA and student t- test. Results: The highest tolerated mean load, in the decreasing order, was observed with GuttaCore (346.3 ± 45.0), GuttaFlow 2 (211.0 ± 29.8), lateral compaction (169.8 ± 23.6), and continuous-wave condensation obturation (167.6 ± 19.3). Conclusion: The GuttaCore system showed superior fracture resistance when compared to GuttaFlow 2, continuous-wave condensation and lateral compaction obturation method.

Fractures appear predominantly in brittle rocks; hence in consolidated formations they are usually sub-vertical and perpendicular to the plane of group of more or less parallel fractures. Vertical fractures refer to the high-angle events (parallel to the borehole) while the horizontal ones indicate the truly horizontal or sub-horizontal events. The unfractured parts of the block matrix in hard rocks are slightly affected by invasion. Added, fracture aperture was estimated using the Dual Laterolog (DLL), which includes the deep (LLD) and the shallow (LLS) resistivities. The area of study is Rudeis-Sidri area, Gulf of Suez, Egypt. Nine Wells were selected for applying the present technique to determine the reservoir performance of Nubia Sandstone Formation in the considered area. The technique depends on the separation between deep and shallow laterolog in case of vertical fracture and the sharp reduction of LLS log in case of horizontal fractures. In high-contrast formation the calculation of fracture aperture can be done if mud conductivity is also known. Also the dipping of the detected fracture is calculated to ensure the type of fracture. The obtained results show that the detected fractures are generally short vertical fractures with a few numbers in the Nubia Sandstone Formation which cannot be the main factor in production (if present) of this formation.

A 30-year-old female patient was reported with pain and swelling in the region of 21. On clinical examination, a swelling was found close to the cervical margin of 21. The suggested treatment plan was periapical surgery of 21. On elevation of flap there was a vertical fracture in cervical region of 21, showing poor prognosis. Extraction of 21 was done and an interdisciplinary approach was carried out with laser-assisted root canal treatment of 12. Also laser troughing in 12 and 22 regions to serve as abutments and an ovate pontic preparation in 11 and 21 regions was carried out. Lasers can be used as an adjunct and/or alternative in the management of multiple dental procedures in the esthetic zone ensuring promising dental outcome.

Study Design Survey study. Objective To determine the global perspective on controversial aspects of sacral fracture classifications. Methods While developing the AOSpine Sacral Injury Classification System, a survey was sent to all members of AOSpine and AOTrauma. The survey asked four yes-or-no questions to help determine the best way to handle controversial aspects of sacral fractures in future classifications. Chi-square tests were initially used to compare surgeons’ answers to the four key questions of the survey, and then the data was modeled through multivariable logistic regression analysis. Results A total of 474 surgeons answered all questions in the survey. Overall 86.9% of respondents felt that the proposed hierarchical nature of injuries was appropriate, and 77.8% of respondents agreed that that the risk of neurologic injury is highest in a vertical fracture through the foramen. Almost 80% of respondents felt that the separation of injuries based on the integrity of L5–S1 facet was appropriate, and 83.8% of surgeons agreed that a nondisplaced sacral U fracture is a clinically relevant entity. Conclusion This study determines the global perspective on controversial areas in the injury patterns of sacral fractures and demonstrates that the development of a comprehensive and universally accepted sacral classification is possible.

The T-shaped pelvic fracture represents from 3%-12% 1 of all acetabulum fractures. It is defined as a transverse acetabulum fracture in combination with a vertical fracture that divides the posterior column from the anterior column (Figure 1). Although the T-type fracture affects both columns, it differs by definition from a fracture of both columns in that part of the acetabulum articular surface still remains stably attached to the iliac pelvic ring.