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Sample records for simulated curved canals

  1. [Shaping ability of multi-taper nickel-titanium files in simulated resin curved root canal].

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    Luo, Hong-Xia; Huang, Ding-Ming; Jia, Liu-He; Luo, Shi-Gao; Gao, Xiao-Jie; Tan, Hong; Zhou, Xue-Dong

    2006-08-01

    To compare the shaping ability of ISO standard stainless steel K files and multi-taper ProTaper nickel-titanium files in simulated resin curved root canals. METHODS Thirty simulated resin root canals were randomly divided into three groups and prepared by stainless steel K files, hand ProTaper, rotary ProTaper, respectively. The amount of material removed from inner and outer wall and canal width after canal preparation was measured, while the canal curvature before and after canal preparation and canals aberrations were recorded. The stainless steel K files removed more material than hand ProTaper and rotary ProTaper at the outer side of apex and inner side of curvature (P ProTaper group (P ProTaper had no evident aberration. The shaping ability of ProTaper is better than stainless steel K files.

  2. A comparison of the shaping ability of reciprocating NiTi instruments in simulated curved canals

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    Young-Sil Yoo

    2011-11-01

    Full Text Available Objectives The study was to compare the shaping ability of Reciproc (VDW and WaveOne (Dentsply Maillefer instruments compared with ProTaper, Profile and hand instrument during the preparation of simulated root canals. Materials and Methods Five groups (n = 5 were established. Reciproc, WaveOne, ProTaper, Profile and K file (K-flexo file were used to prepare the resin simulated canals. A series of preoperative and postoperative images were taken by a microscope and superimposed in 2 different layers. The amount of resin removed from both the inner and the outer sides of the canal was measured to the level of 10 mm from the apical tip, with a 1 mm increment. Results The mean of resin removal from the inner canal wall was not different from the outer canal wall for Reciproc and WaveOne groups at apical third (1 - 3 mm level. There was no difference in the change of working length and maintenance of canal curvature. NiTi instruments are superior to stainless-steel K file in their shaping ability. Conclusions Within the limitation of this present study, Reciproc and WaveOne instruments maintained the original canal curvature in curved canals better than ProTaper and Profile, which tend to transport towards the outer canal wall of the curve in the apical part of the canal.

  3. Preparation of severely curved simulated root canals using engine-driven rotary and conventional hand instruments.

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    Szep, S; Gerhardt, T; Leitzbach, C; Lüder, W; Heidemann, D

    2001-03-01

    This in vitro study evaluated the efficacy and safety of six different nickel-titanium engine-driven instruments used with a torque-controlled engine device and nickel-titanium hand and stainless steel hand instruments in preparation of curved canals. A total of 80 curved (36 degrees) simulated root canals were prepared. Images before and after were superimposed, and instrumentation areas were observed. Time of instrumentation, instrument failure, change in working length and weight loss were also recorded. Results show that stainless steel hand instruments cause significantly less transportation towards the inner wall of the canal than do nickel-titanium hand instruments. No instrument fracture occurred with hand instruments, but 30-60% breakage of instruments was recorded during instrumentation with the engine-driven devices. The working length was maintained by all types of instruments. Newly developed nickel-titanium rotary files were not able to prevent straightening of the severely curved canals when a torque-controlled engine-driven device was used.

  4. Shaping ability of several nickel–titanium systems in double-curved simulated canals

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    Mothanna Alrahabi

    2017-06-01

    Conclusion: The iRaCe, ProTaper Next, Wave One, and TF systems preserved the original shape of the double-curved (S-shaped canal with minimum root canal transportation. These systems produced satisfactory root canal instrumentation in S-shaped canals.

  5. Mechanical response of nickel-titanium instruments with different cross-sectional designs during shaping of simulated curved canals.

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    Kim, H C; Kim, H J; Lee, C J; Kim, B M; Park, J K; Versluis, A

    2009-07-01

    To evaluate how different cross-sectional designs affect stress distribution in nickel-titanium (NiTi) instruments during bending, torsion and simulated shaping of a curved canal. Four NiTi rotary instruments with different cross-sectional geometries were selected: ProFile and HeroShaper systems with a common triangle-based cross section, Mtwo with an S-shaped rectangle-based design and NRT with a modified rectangle-based design. The geometries of the selected files were scanned in a micro-CT and three-dimensional finite-element models were created for each system. Stiffness characteristics for each file system were determined in a series of bending and torsional conditions. Canal shaping was simulated by inserting models of the rotating file into a 45 degrees curved canal model. Stress distribution in the instruments was recorded during simulated shaping. After the instruments were retracted from the canal, residual stresses and permanent bending of their tips due to plastic deformation were determined. The greatest bending and torsional stiffness occurred in the NRT file. During simulated shaping, the instruments with triangle-based cross-sectional geometry had more even stress distributions along their length and had lower stress concentrations than the instruments with rectangle-based cross sections. Higher residual stresses and plastic deformations were found in the Mtwo and NRT with rectangle-based cross-sectional geometries. Nickel-titanium instruments with rectangle-based cross-sectional designs created higher stress differentials during simulated canal shaping and may encounter higher residual stress and plastic deformation than instruments with triangle-based cross sections.

  6. Curved canals: Ancestral files revisited

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    Jain Nidhi

    2008-01-01

    Full Text Available The aim of this article is to provide an insight into different techniques of cleaning and shaping of curved root canals with hand instruments. Although a plethora of root canal instruments like ProFile, ProTaper, LightSpeed ® etc dominate the current scenario, the inexpensive conventional root canal hand files such as K-files and flexible files can be used to get optimum results when handled meticulously. Special emphasis has been put on the modifications in biomechanical canal preparation in a variety of curved canal cases. This article compiles a series of clinical cases of root canals with curvatures in the middle and apical third and with S-shaped curvatures that were successfully completed by employing only conventional root canal hand instruments.

  7. An evaluation of .06 tapered gutta-percha cones for filling of .06 taper prepared curved root canals.

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    Gordon, M P J; Love, R M; Chandler, N P

    2005-02-01

    To compare the area occupied by gutta-percha, sealer, or void in standardized .06 tapered prepared simulated curved canals and in mesio-buccal canals of extracted maxillary first molars filled with a single .06 gutta-percha point and sealer or lateral condensation of multiple .02 gutta-percha points and sealer. Simulated canals in resin blocks with either a 30 degrees curve and radius of 10.5 mm (n = 20) or a 58 degrees curve and 4.7 mm radius (n = 20) and curved mesio-buccal canals of extracted maxillary first molars (n = 20) were prepared using .06 ProFiles in a variable tip crown-down sequence to an apical size 35 at 0.5 mm from the canal terminus or apical foramen. Ten 30 degrees and 58 degrees curved resin canals and 10 canals in the extracted teeth group were obturated with .02 taper gutta-percha cones and AH 26 sealer using lateral condensation. The time required to obturate was recorded. The remaining canals were obturated with a single .06 taper gutta-percha cone and AH 26 sealer. Excess gutta-percha was removed from the specimens using heat and the warm mass vertically condensed. Horizontal sections were cut at 0.5, 1.5, 2.5, 4.5, 7.5 and 11.5 mm from the canal terminus or apical foramen. Colour photographs were taken using an Olympus 35 mm camera attached to a stereomicroscope set at x40 magnification, and then digitized using a flatbed scanner. The cross-sectional area of the canal contents was analysed using Adobe PhotoShop. The percentage of gutta-percha, sealer or voids to the total root canal area were derived and data analysed using unpaired Student's t-test and the Mann-Whitney U-test. In the 30 degrees curved canals the levels had between 94 and 100% of the area filled with gutta-percha with no significant difference (P > 0.05) between the lateral condensation and single cone techniques. In the 58 degrees curved canals the levels had 92-99% of the area filled with gutta-percha, with the single cone technique having significantly (P 0.05) between

  8. [Evaluation of preparation of curved root canals using hand-used ProTaper].

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    Nie, Min; Zhao, Xin-Chen; Peng, Bin; Fan, Ming-Wen; Bian, Zhuan

    2009-05-01

    To evaluate the shaping ability of hand-used ProTaper on curved canals using Endodontic Cube. Fifty-four curved root canals in vitro were selected and divided into three groups according to the curved degree (alpha), group A: 0 degrees hand-used ProTaper. Before and after shaping, photograph of all the sections were taken under a stereomicroscope. Statistical analyses were performed. The dentin cutting quantity of the whole canal prepared with ProTaper in group B and C was larger than that of group A. The deviation distance of the whole canal prepared by ProTaper in group C was significantly larger than that in group A, and the deviation distance in middle portion larger than that in group B. The maintaining ability in the middle portion of group C by ProTaper was worse than that of group A and B. The curvature of root canal may increase the cutting quantity of the -dentin and reduce the ability of remaining original canal shape prepared by ProTaper.

  9. Wear promoted in the apical third of simulated canals after instrumentation with protaper universal system

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    Kathrein Tapia da Silva

    2009-10-01

    Full Text Available OBJECTIVE: This study evaluated the wear in the apical third of simulate canals after preparation with ProTaper Universal Rotary System. MATERIAL AND METHODS: 24 sets of instruments were used in 24 simulated canals in transparent epoxy resin blocks with degree of curvature of either 20°or 40°. The canals were photographed preoperatively and after preparation of the apical stop with ProTaper F3, F4 and F5 instruments. The initial and final images were exported to Adobe Photoshop® software and superimposed to detect the root canal wall differences (in mm between them, in two points located 1 (A and 5 (B mm from the point where the working length was established. Data were subjected to analysis of variance to verify the existence of interaction among the factors: canal curvature, instrument size and curve location. Significant level was set at 5%. RESULTS: Regardless of the location and the canal curvature, F4 and F5 instruments produced the greatest wear (p<0.05. CONCLUSIONS: There was a deviation from the original pathway towards the outside of the root curvature in both analyzed points. All instruments produced canal transportation, but the F4 and F5 instruments produced more than the other instruments, and should thus be used with care in curved canals.

  10. Influence of a glide path on apical extrusion of debris during canal preparation using single-file systems in curved canals.

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    Topçuoğlu, H S; Düzgün, S; Akpek, F; Topçuoğlu, G; Aktı, A

    2016-06-01

    To evaluate the effect of a glide path on the amount of apically extruded debris during canal preparation using single-file systems in curved canals. Ninety extracted mandibular molar teeth were randomly assigned to six groups (n = 15 for each group) for canal instrumentation. Endodontic access cavities were prepared in each tooth. In three of the six groups, a glide path was not created whereas a glide path was created using PathFile instruments on the mesial canals of all teeth in the remaining three groups. The mesial canals of the teeth were then instrumented with the following single-file instrument systems: WaveOne, Reciproc and OneShape. Debris extruded apically during instrumentation was collected into pre-weighed Eppendorf tubes. The tubes were then stored in an incubator at 70 °C for 5 days. The weight of the dry extruded debris was established by subtracting the pre-instrumentation and post-instrumentation weight of the Eppendorf tubes for each group. The data obtained were analysed using one-way analysis of variance (anova) and Tukey's post hoc tests. The OneShape file was associated with less debris extrusion than the Reciproc and WaveOne files when canal instrumentation was performed without a glide path (P files (P > 0.05). There was no significant difference amongst the OneShape, Reciproc and WaveOne files when a glide path was created before canal preparation in curved root canals (P > 0.05). All systems extruded significantly less debris in groups with a glide path than in groups without a glide path (P < 0.05). All instruments were associated with apical extrusion of debris. Creating a glide path prior to canal instrumentation reduced the amount of apically extruded debris in curved canals. © 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  11. Shaping ability of nickel-titanium rotary instruments in curved root canals.

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    Talati, Ali; Moradi, Saeed; Forghani, Maryam; Monajemzadeh, Ali

    2013-01-01

    Disinfection and subsequent obturation of the root canal space require adequate mechanical enlargement of the canals. The purpose of this in vitro study was to compare the shaping ability of Mtwo, RaCe and Medin rotary instruments during the preparation of curved root canals. Sixty mesiobuccal root canals of mandibular molars with severe curvatures between 25-35(°) and radius of 4-9 mm were randomly divided into three groups of 20 canals each. Using pre- and post-instrumentation radiographs, straightening of the canal and the apical transportation were determined with AutoCAD software. The data were analyzed using Chi square, analysis of variance, and post-hoc tests and the significance level was set at P0.05). Under the conditions of this in vitro study, Mtwo instruments seemed superior to the two other rotary instruments.

  12. Maxillary lateral incisors with two canals and two separate curved roots

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    Ajit George Mohan

    2012-01-01

    Full Text Available Variation in the roots and root canal anatomy seems to be the norm rather than an exception. For a successful endodontic treatment, a clinician should have a thorough knowledge of the internal and external dental anatomy and its variations. Maxillary lateral incisors usually exhibit single canal with a single root. In this case, clinical examination and radiographs clearly demonstrates the presence of two root canals with two separate curved roots. This case report emphasizes the need for attention during endodontic management of maxillary lateral incisors.

  13. Shaping ability of NT Engine and McXim rotary nickel-titanium instruments in simulated root canals. Part 2.

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    Thompson, S A; Dummer, P M

    1997-07-01

    The aim of this laboratory-based study was to determine the shaping ability of NT Engine and McXim nickel-titanium rotary instruments in simulated root canals. A total of 40 canals with four different shapes in terms of angle and position of curve were prepared with NT Engine and McXim instruments, using the technique recommended by the manufacturer. Part 2 of this report describes the efficacy of the instruments in terms of prevalence of canal aberrations, the amount and direction of canal transportation and overall postoperative shape. Pre- and postoperative images of the canals were taken using a video camera attached to a computer with image analysis software. The pre- and postoperative views were superimposed to highlight the amount and position of material removed during preparation. No zips, elbows, perforations or danger zones were created during preparation. Forty-two per cent of canals had ledges on the outer aspect of the curve, the majority of which (16 out of 17) occurred in canals with short acute curves. There were significant differences (P Engine and McXim rotary nickel-titanium instruments created no aberrations other than ledges and produced only minimal transportation. The overall shape of canals was good.

  14. Efficacy of Reciproc(®) and Profile(®) Instruments in the Removal of Gutta-Percha from Straight and Curved Root Canals ex Vivo.

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    Marfisi, Karem; Mercadé, Montserrat; Plotino, Gianluca; Clavel, Tatiana; Duran-Sindreu, Fernando; Roig, Miguel

    2015-01-01

    To compare the efficacy of Reciproc(®) (VDW GmbH) and ProFile(®) (Dentsply Maillefer) instruments at removing gutta-percha from straight and curved root canals ex vivo filled using the cold lateral condensation and GuttaMaster(®) (VDW GmbH) techniques. Forty mesial roots of mandibular molars with two curved canals and 80 single-rooted teeth with straight root canals, a total of 160 root canals, were randomly assigned to eight groups (canals per group = 20) according to filling technique, retreatment instrument and root canal curvature as follows: Group I, cold lateral condensation/ProFile(®)/straight; Group II, cold lateral condensation/ProFile(®)/curved; Group III, cold lateral condensation/Reciproc(®)/straight; Group IV, cold lateral condensation/Reciproc(®)/curved; Group V, GuttaMaster(®)/ProFile(®)/straight; Group VI, GuttaMaster(®)/ProFile(®)/curved; Group VII, GuttaMaster(®)/Reciproc(®)/straight; and Group VIII, GuttaMaster(®)/Reciproc(®)/curved. The following data were recorded: procedural errors, retreatment duration and canal wall cleanliness. Means and standard deviations were calculated and analysed using the Kruskal-Wallis test, one-way analysis of variance and Tukey's test (P straight (P = 0.0001) and curved (P = 0.0003) root canals. Reciproc(®) were statistically more effective than ProFile(®) instruments in removing GuttaMaster(®) from straight root canals (P = 0.021). Regardless of filling technique or retreatment instrument, gutta-percha was removed more rapidly from curved than from straight root canals (P = 0.0001). Neither system completely removed filling material from the root canals. Compared with ProFile(®) instruments, Reciproc(®) instruments removed GuttaMaster(®) filling material from straight and curved root canals more rapidly.

  15. Cleaning and shaping curved root canals: Mtwo® vs ProTaper® instruments, a lab comparison

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    Kuzekanani Maryam

    2009-01-01

    Full Text Available Objectives: The purpose of this study was to compare root canal preparation in curved canals in molar teeth with the rotary NiTi Mtwo and ProTaper systems in terms of canal shape and smear layer. Materials and Methods: Mesiobuccal canals of 60 molar teeth with angles of curvature between 25 and 35 degrees were prepared with a torque controlled low speed engine; 30 canals for each system. Each individual instrument was used to prepare four root canals and the time required for preparation was recorded. Standardized radiographs were taken before and following instrumentation and used to determine changes in canal curvature. Results: There was no significant difference in preparation time between the two systems. No instruments separated during use. The Mtwo system gave a statistically smaller change in canal curvature and thus was better for maintaining the original shape of the root canal, with less transportation (P less than 0.05. The greatest difference was seen for maxillary molar teeth. When prepared root canals were examined by SEM there was no difference between the two systems at the coronal, middle or apical thirds. Conclusion: Overall, the results of this study suggest that Mtwo instruments are preferable for situations where canals are curved, particularly for maxillary molars.

  16. Management of curved root canals in endodontics: clinical case of retreatment

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    Meneses Guzman, Jose Pablo

    2005-01-01

    The management of curved root canals in endodontics therapy has required time, patience and skill of the operator, and lots collaboration by the patient. Proper cleaning, disinfection, conformation and root canal filling, in most cases, has prevented the appearance of lesions of bacterial origin to apical or maintenance of these lesions in teeth that are portrayed level. A clinical case is described of retreatment of a first mandibular molar by conventional endodontic treatment with their respective steps, to achieve signs of tissue repair at the apical level. (author) [es

  17. Effect of Patency File on Transportation and Curve Straightening in Canal Preparation with ProTaper System.

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    Hasheminia, Seyed Mohsen; Farhadi, Nastaran; Shokraneh, Ali

    2013-01-01

    The aim of this ex vivo study was to evaluate the effect of using a patency file on apical transportation and curve straightening during canal instrumentation with the ProTaper rotary system. Seventy permanent mandibular first molars with mesiobuccal canals, measuring 18-23 mm in length and with a 25-40° curvature (according to the Schneider method), were selected. The working lengths were determined and the teeth were mounted and divided into two experimental groups: (A) prepared by the ProTaper system without using a patency file (n = 35) and (B) prepared by the ProTaper system using a patency file (n = 35). Radiographs taken before and after the preparation were imported into Photoshop software and the apical transportation, and curve straightening were measured. Data were analyzed using independent t-test. Partial correlation analysis was performed to evaluate the relationship between the initial curvature, transportation, and curve straightening (α = 0.05). Using a patency file during canal preparation significantly decreased both apical transportation and curve straightening (P system.

  18. Hand-operated and rotary ProTaper instruments: a comparison of working time and number of rotations in simulated root canals.

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    Pasqualini, Damiano; Scotti, Nicola; Tamagnone, Lorenzo; Ellena, Federica; Berutti, Elio

    2008-03-01

    The aim of this study was to compare the effective shaping time and number of rotations required by an endodontist working with hand and rotary ProTaper instruments to completely shape simulated root canals. Eighty Endo Training Blocks (curved canal shape) were used. Manual preflaring was performed with K-Flexofiles #08-10-12-15-17 and #20 Nitiflex at a working length of 18 mm. Specimens were then randomly assigned to 2 different groups (n = 40); group 1 was shaped by using hand ProTaper and group 2 with ProTaper rotary. The number of rotations made in the canal and the effective time required to achieve complete canal shaping were recorded for each instrument. Differences between groups were analyzed with the nonparametric Mann-Whitney U test (P Hand ProTaper required significantly fewer rotations (P ProTaper, whereas the effective working time to fully shape the simulated canal was significantly higher (P hand ProTaper.

  19. Comparative evaluation of fracture and defect in reciproc and rotary files in severe curved root canals

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    Mahdis Bagherian

    2015-03-01

    Full Text Available Introduction: Root canal instrumentation is an important phase in root canal therapy. Since success in endodontic treatment depends on file defect and fracture, the aim of this study was to compare the evaluation of defect and fracture in rotary and reciproc files in severe curved root canals. Materials & Methods: In this experimental study, 60 mesial canals of human closed apex molars with more than 30° canal curvature were randomly divided into two groups. In first group M-two rotary files number# 15, 20, and 25 and in second group R25 reciproc file were used for filing, respectively. A ×8 magnifier was applied to evaluate the defect or fracture presence in each side and if it were observed, a new file would be replaced. Therefore, the number of prepared canals with each file and fractured or defective files and the place of fracture in root canal were recorded. Kaplan Meier curve and log rank test were done by using SPSS v.22. Results: In rotary group, seven and two files were fractured and defected, respectively and four files were fractured and no defect was observed in reciproc group. Although the mean of the number of prepared canals until fracture or defect in rotary and reciproc groups was 3.3 and 7.06, respectively, there were no significant differences between two systems. All file’s fractures occurred in apical regions . Conclusion: The results showed that there was no significant difference in defects or fractures of rotary and reciproc systems. Reciproc instruments can be more effective than rotary ones because the root canal preparation in rotary instruments is longer than in reciproc system.

  20. Cone-beam computed tomography analysis of curved root canals after mechanical preparation with three nickel-titanium rotary instruments

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    Elsherief, Samia M.; Zayet, Mohamed K.; Hamouda, Ibrahim M.

    2013-01-01

    Cone beam computed tomography is a 3-dimensional high resolution imaging method. The purpose of this study was to compare the effects of 3 different NiTi rotary instruments used to prepare curved root canals on the final shape of the curved canals and total amount of root canal transportation by using cone-beam computed tomography. A total of 81 mesial root canals from 42 extracted human mandibular molars, with a curvature ranging from 15 to 45 degrees, were selected. Canals were randomly divided into 3 groups of 27 each. After preparation with Protaper, Revo-S and Hero Shaper, the amount of transportation and centering ability that occurred were assessed by using cone beam computed tomography. Utilizing pre- and post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. Canals were metrically assessed for changes (surface area, changes in curvature and transportation) during canal preparation by using software SimPlant; instrument failures were also recorded. Mean total widths and outer and inner width measurements were determined on each central canal path and differences were statistically analyzed. The results showed that all instruments maintained the original canal curvature well with no significant differences between the different files (P = 0.226). During preparation there was failure of only one file (the protaper group). In conclusion, under the conditions of this study, all instruments maintained the original canal curvature well and were safe to use. Areas of uninstrumented root canal wall were left in all regions using the various systems. PMID:23885273

  1. Canal shaping of different single-file systems in curved root canals

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    Maurizio D'Amario

    2017-12-01

    Full Text Available Background/Purpose: This study compared maintenance of canal anatomy, occurrence of apical transportation, and working time observed after instrumentation with One Shape New Generation rotary system (Micro-Mega, with those observed after instrumentation with Reciproc (VDW and WaveOne (Dentsply-Maillefer reciprocating systems. Materials and methods: The mesial canals of 45 mandibular molars (curvature angles between 35° and 45° were selected. Specimens were randomly divided into three groups, and canal preparations were performed using One Shape, Reciproc, or WaveOne systems (size #25. A digital double radiographic technique was used to determine apical transportation and change in angle of curvature. Also, working time and instrument failures were recorded. Data were statistically analyzed. Results: During preparation, no file fractured. No statistically significant differences were found among groups. No system showed a significantly faster preparation time than others (P>0.05. All instruments maintained the original canal curvature well and were safe to use. Conclusion: Both continuous rotary instrument and reciprocating systems did not have any influence on the presence of apical transportation or caused an alteration in angle of canal curvature. Keywords: canal curvature, canal straightening, endodontics, reciprocating motion, single file instrumentation

  2. Real-time evaluation of two light delivery systems for photodynamic disinfection of Candida albicans biofilm in curved root canals.

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    Sabino, C P; Garcez, A S; Núñez, S C; Ribeiro, M S; Hamblin, M R

    2015-08-01

    Antimicrobial photodynamic therapy (APDT) combined with endodontic treatment has been recognized as an alternative approach to complement conventional root canal disinfection methods on bacterial biofilms. We developed an in  vitro model of bioluminescent Candida albicans biofilm inside curved dental root canals and investigated the microbial reduction produced when different light delivery methods are employed. Each light delivery method was evaluated in respect to the light distribution provided inside curved root canals. After conventional endodontic preparation, teeth were sterilized before canals were contaminated by a bioluminescent strain of C. albicans (CEC789). Methylene blue (90 μM) was introduced into the canals and then irradiated (λ = 660 nm, P = 100 mW, beam diameter = 2 mm) with laser tip either in contact with pulp chamber or within the canal using an optical diffuser fiber. Light distribution was evaluated by CCD camera, and microbial reduction was monitored through bioluminescence imaging. Our findings demonstrated that the bioluminescent C. albicans biofilm model had good reproducibility and uniformity. Light distribution in dental tissue was markedly dependent on the light delivery system, and this strategy was directly related to microbial destruction. Both light delivery systems performed significant fungal inactivation. However, when irradiation was performed with optical diffuser fiber, microbial burden reduction was nearly 100 times more effective. Bioluminescence is an interesting real-time analysis to endodontic C. albicans biofilm inactivation. APDT showed to be an effective way to inactivate C. albicans biofilms. Diffuser fibers provided optimized light distribution inside curved root canals and significantly increased APDT efficiency.

  3. Working length changes in curved canals after coronal flaring by using rotary files and hand file: An in vitro study.

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    Kumar, Rahul; Khambete, Neha; Patil, Suvarna; Hoshing, Upendra; Medha, Ashish; Shetty, Roshan

    2013-09-01

    This in vitro investigation examined the effect of early coronal flaring (CF) and late CF on the working length (WL) in curved root canals. The objective of this study was to determine if canal length is altered as a result of CF in curved canals of molar roots. The conditions compared were combinations of (a) stainless steel hand files using Gates Glidden (G. G.) drills (SS) versus nickel-titanium rotary files (Ni-Ti); and (b) early CF (flaring completed before WL determination) versus late CF (flaring completed after WL determination). Selected were 90 canals of extracted maxillary or mandibular first molars (mesial root of mandibular molars and the mesiobuccal root of the maxillary molars) from three groups. CF was accomplished for the SS group using G. G. drills and for the Ni-Ti group using rotary ProTaper and Hero Shaper files. WL was determined by a digital vernier caliper before CF, immediately after CF, and again after canal preparation. A repeated measures analysis of variance (ANOVA) test and a Tukey's multiple prosthoc test were used for this study. Results indicated that WL decreased for all canals as a result of canal preparation. The mean decrease in WL was significantly greater for the SS group (-0.77 ± 0.42 mm) than for the Ni-Ti groups (-0.33 mm ± 0.44). Less change in WL occurred in all groups when initial WL was determined after CF. WL in curved canals consistently decreases during the course of instrumentation. Clinician should keep this in mind for better treatment outcome.

  4. Evaluation of deformation and fracture of three single-file NiTi rotary instruments: ProTaper F2, WaveOne Primary and OneShape in simulated curved canals

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    Mina A. Shenouda

    2018-06-01

    Full Text Available Purpose. The aim of the current study was to compare the incidence of deformation and fracture in three single-file NiTi instruments: ProTaper F2, WaveOne Primary and OneShape. Methods. Fifteen instruments were equally divided into three groups: ProTaper F2 in reciprocation, WaveOne Primary in reciprocation and OneShape in continuous rotation. Each instrument was used to prepare standardized simulated curved canals in resin blocks until fracture had occurred. Following each canal preparation, the instruments were examined for deformation both by naked eye inspection and stereomicroscopic examination. The average number of canals prepared until the first incidence of cracks and the average lifespan of the instruments were calculated. Data were analysed using one-way ANOVA and two-sample t-test. Results. There was no statistically significant difference between ProTaper and WaveOne instruments in both the incidence of cracks and the average lifespan (P > 0.05. OneShape instruments had a significantly delayed incidence of cracks and a longer lifespan than both ProTaper and WaveOne instruments (P < 0.05; however, OneShape instruments showed a noticeable early plastic deformation. Conclusion: PT F2 instrument was comparable to WO Primary instrument in terms of fracture resistance, while OS instrument had more fracture resistance than both PT F2 and WO Primary instruments.

  5. Fitness of gutta-percha cones in curved root canals prepared with reciprocating files correlated with tug-back sensation.

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    Yoon, Heeyoung; Baek, Seung-Ho; Kum, Kee-Yeon; Kim, Hyeon-Cheol; Moon, Young-Mi; Fang, Denny Y; Lee, WooCheol

    2015-01-01

    The purpose of this study was to evaluate the gutta-percha-occupied area (GPOA) and the relationship between GPOA and tug-back sensations in canals instrumented with reciprocating files. Twenty curved canals were instrumented using Reciproc R25 (VDW, Munich, Germany) (group R) and WaveOne Primary (Dentsply Maillefer, Ballaigues, Switzerland) (group W), respectively (n = 10 each). The presence or absence of a tug-back sensation was decided for both of #25/.08 and #30/.06 cones in every canal. The percentage of GPOA at 1-, 2-, and 3-mm levels from the working length was calculated using micro-computed tomographic imaging. The correlation between the sum of the GPOA and the presence of a tug-back sensation was also investigated. The data were analyzed statistically at P = .05. A tug-back sensation was present in 45% and 100% canals for #25/.08 and #30/.06 cones, respectively, with a significant difference (P sensation (P .05). Under the conditions of this study, the tug-back sensation can be a definitive determinant for indicating higher cone fitness in the curved canal regardless of the cone type. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  6. Influence of the geometry of curved artificial canals on the fracture of rotary nickel-titanium instruments subjected to cyclic fatigue tests.

    Science.gov (United States)

    Lopes, Hélio P; Vieira, Márcia V B; Elias, Carlos N; Gonçalves, Lucio S; Siqueira, José F; Moreira, Edson J L; Vieira, Victor T L; Souza, Letícia C

    2013-05-01

    This study evaluated the influence of different features of canal curvature geometry on the number of cycles to fracture of a rotary nickel-titanium endodontic instrument subjected to a cyclic fatigue test. BioRaCe BR4C instruments (FKG Dentaire, La Chaux-de Fonds, Switzerland) were tested in 4 grooves simulating curved metallic artificial canals, each one measuring 1.5 mm in width, 20 mm in total length, and 3.5 mm in depth with a U-shaped bottom. The parameters of curvature including the radius and arc lengths and the position of the arc differed in the 4 canal designs. Fractured surfaces and helical shafts of the separated instruments were analyzed by scanning electron microscopy. The Student's t test showed that a significantly lower number of cycles to fracture values were observed for instruments tested in canals with the smallest radius, the longest arc, and the arc located in the middle portion of the canal. Scanning electron microscopic analysis of the fracture surfaces revealed morphologic characteristics of ductile fracture. Plastic deformation was not observed in the helical shaft of the fractured instruments. Curvature geometry including the radius and arc lengths and the position of the arc along the root canal influence the number of cycles to fracture of rotary nickel-titanium instruments subjected to flexural load. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  7. Comparison among manual instruments and PathFile and Mtwo rotary instruments to create a glide path in the root canal preparation of curved canals.

    Science.gov (United States)

    Alves, Vanessa de Oliveira; Bueno, Carlos Eduardo da Silveira; Cunha, Rodrigo Sanches; Pinheiro, Sérgio Luiz; Fontana, Carlos Eduardo; de Martin, Alexandre Sigrist

    2012-01-01

    Nickel-titanium rotary instruments reduce procedural errors and the time required to finish root canal preparation. The goal of this study was to evaluate the occurrences of apical transportation and canal aberrations produced with different instruments used to create a glide path in the preparation of curved root canals, namely manual K-files (Dentsply Maillefer, Ballaigues, Switzerland) and PathFile (Dentsply Maillefer) and Mtwo (Sweden and Martina, Padua, Italy) nickel-titanium rotary files. The mesial canals of 45 mandibular first and second molars (with curvature angles between 25° and 35°) were selected for this study. The specimens were divided randomly into 3 groups with 15 canals each, and canal preparation was performed by an endodontist using #10-15-20 K-type stainless steel manual files (group M), #13-16-19 PathFile rotary instruments (group PF), and #10-15-20 Mtwo rotary instruments (group MT). The double digital radiograph technique was used, pre- and postinstrumentation, to assess whether apical transportation and/or aberration in root canal morphology occurred. The initial and final images of the central axis of the canals were compared by superimposition through computerized analysis and with the aid of magnification. The specimens were analyzed by 3 evaluators, whose calibration was checked using the Kendall agreement test. No apical transportation or aberration in root canal morphology occurred in any of the teeth; therefore, no statistical analysis was conducted. Neither the manual instruments nor the PathFile or Mtwo rotary instruments used to create a glide path had any influence on the occurrence of apical transportation or produced any canal aberration. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  8. [Shaping ability of two nickel-titanium rotary systems in simulated S-shaped canals].

    Science.gov (United States)

    Luo, Hong-xia; Huang, Ding-ming; Zhang, Fu-hua; Tan, Hong; Zhou, Xue-dong

    2008-01-01

    To evaluate the shaping ability of two nickel-titanium rotary systems (ProTaper and Hero642) in simulated S-shaped canals. Thirty simulated S-shaped canals were randomly divided into three groups and prepared by ProTaper, Hero642, ProTaper combined with Hero642 respectively. All the canals were scanned before and after instrumentation, and the amount of material removed in the inner and outer wall and the canal width after instrumentation were measured with a computer image analysis program. There was significant difference in the amount of material removed at the inner side of apical curvature and outer side of apex between ProTaper combined with Hero642 and ProTaper files (P Hero642, and the taper of canals were better than those prepared by Hero642. ProTaper combined with Hero 642 had better shaping ability to maintain the original shape and could create good taper canals in the simulated S-shaped canal model.

  9. Clinical and Radiographic Evaluation of Procedural Errors during Preparation of Curved Root Canals with Hand and Rotary Instruments: A Randomized Clinical Study

    Science.gov (United States)

    Khanna, Rajesh; Handa, Aashish; Virk, Rupam Kaur; Ghai, Deepika; Handa, Rajni Sharma; Goel, Asim

    2017-01-01

    Background: The process of cleaning and shaping the canal is not an easy goal to obtain, as canal curvature played a significant role during the instrumentation of the curved canals. Aim: The present in vivo study was conducted to evaluate procedural errors during the preparation of curved root canals using hand Nitiflex and rotary K3XF instruments. Materials and Methods: Procedural errors such as ledge formation, instrument separation, and perforation (apical, furcal, strip) were determined in sixty patients, divided into two groups. In Group I, thirty teeth in thirty patients were prepared using hand Nitiflex system, and in Group II, thirty teeth in thirty patients were prepared using K3XF rotary system. The evaluation was done clinically as well as radiographically. The results recorded from both groups were compiled and put to statistical analysis. Statistical Analysis: Chi-square test was used to compare the procedural errors (instrument separation, ledge formation, and perforation). Results: In the present study, both hand Nitiflex and rotary K3XF showed ledge formation and instrument separation. Although ledge formation and instrument separation by rotary K3XF file system was less as compared to hand Nitiflex. No perforation was seen in both the instrument groups. Conclusion: Canal curvature played a significant role during the instrumentation of the curved canals. Procedural errors such as ledge formation and instrument separation by rotary K3XF file system were less as compared to hand Nitiflex. PMID:29042727

  10. [Continuous observation of canal aberrations in S-shaped simulated root canal prepared by hand-used ProTaper files].

    Science.gov (United States)

    Xia, Ling-yun; Leng, Wei-dong; Mao, Min; Yang, Guo-biao; Xiang, Yong-gang; Chen, Xin-mei

    2009-08-01

    To observe the formation of canal aberrations in S-shaped root canals prepared by every file of hand-used ProTaper. Fifteen S-shaped simulated resin root canals were selected. Each root canal was prepared by every file of hand-used ProTaper following the manufacturer instruction. The images of canals prepared by S1, S2, F1, F2 and F3 were taken and stored, which were divided into group S1, S2, F1, F2 and F3. One image of canal unprepared was superposed with the images of the same root canal in these five groups respectively to observe the types and number of canal aberrations, which included unprepared area, danger zone, ledge, elbow, zip and perforation. SPSS12.0 software pakage was used for Fisher's exact probabilities in 2x2 table. Unprepared area decreased following preparation by every file of ProTaper, but it still existed when the canal preparation was finished. The incidence of danger zone, elbow and zip in group F1 was 15/15, 11/15, 4/15, respectively, which was significantly higher than that in group S2(2/15,0,0) (PProTaper.The presence of unprepared area suggests that it is essential to rinse canal abundantly during complicated canal preparation and canal antisepsis after preparation.

  11. Simulating Supernova Light Curves

    Energy Technology Data Exchange (ETDEWEB)

    Even, Wesley Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dolence, Joshua C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-05

    This report discusses supernova light simulations. A brief review of supernovae, basics of supernova light curves, simulation tools used at LANL, and supernova results are included. Further, it happens that many of the same methods used to generate simulated supernova light curves can also be used to model the emission from fireballs generated by explosions in the earth’s atmosphere.

  12. Simulating Supernova Light Curves

    International Nuclear Information System (INIS)

    Even, Wesley Paul; Dolence, Joshua C.

    2016-01-01

    This report discusses supernova light simulations. A brief review of supernovae, basics of supernova light curves, simulation tools used at LANL, and supernova results are included. Further, it happens that many of the same methods used to generate simulated supernova light curves can also be used to model the emission from fireballs generated by explosions in the earth's atmosphere.

  13. Assessing apical transportation in curved canals: comparison between cross-sections and micro-computed tomography

    Directory of Open Access Journals (Sweden)

    Laila Gonzales Freire

    2012-06-01

    Full Text Available The aim of this study was to compare two methods of assessing apical transportation in curved canals after rotary instrumentation, namely, cross-sections and micro-computed tomography (µCT. Thirty mandibular molars were divided into two groups and prepared according to the requirements of each method. In G1 (cross-sections, teeth were embedded in resin blocks and sectioned at 2.0, 3.5, and 5.0 mm from the anatomic apex. Pre- and postoperative sections were photographed and analyzed. In G2 (µCT, teeth were embedded in a rubber-base impression material and scanned before and after instrumentation. Mesiobuccal canals were instrumented with the Twisted File (TF system (SybronEndo, Orange, USA, and mesiolingual canals, with the EndoSequence (ES system (Brasseler, Savannah, USA. Images were reconstructed, and sections corresponding to distances 2.0, 3.5, and 5.0 mm from the anatomic apex were selected for comparison. Data were analyzed using Mann-Whitney's test at a 5% significance level. The TF and ES instruments produced little deviation from the root canal center, with no statistical difference between them (P > 0.05. The canal transportation results were significantly lower (0.056 mm in G2 than in G1 (0.089 mm (p = 0.0012. The µCT method was superior to the cross-section method, especially in view of its ability to preserve specimens and provide results that are more closely related to clinical situations.

  14. Effectiveness of different irrigation systems on filling of simulated lateral canals

    Directory of Open Access Journals (Sweden)

    sehnaz Yilmaz

    2016-09-01

    Conclusions: Sonically or ultrasonically irrigation showed significant differences on the filling of the simulated lateral canals at the middle third of the root canals. Ultrasonic activation of the irrigants represented better results in radiographic and cleared specimen evaluation. [Cukurova Med J 2016; 41(3.000: 515-520

  15. Canal Centring Ability of ProTaper and Mtwo Rotary Systems in Curved Canals

    Directory of Open Access Journals (Sweden)

    Turkaydin Dilek Erbay

    2014-07-01

    Full Text Available The purpose of this investigation was to compare centring ratio of ProTaper and Mtwo rotary systems. 60 mandibular molar teeth which had 25, 30 and 35 degree curvature in mesio-buccal root canal were used. Group 1 had 25°, Group 2 had 30°, and Group 3 had 35° curvatures. The roots were sectioned horizontally at 2 mm away from the apex. The apical region was then observed under a stereo-microscope. In each group, teeth were instrumented using ProTaper and Mtwo systems. After canal preparation, digital images of apical part of canals were taken. These images were then superimposed by using Adobe Photoshop CS2 programme. The data were analyzed using ANOVA and Student’s t-test.

  16. In-vitro evaluation of the effect of canal curvature on adaptation of gutta-percha in canals obturated with HEROfill system by CBCT

    International Nuclear Information System (INIS)

    Zarei, M.; Talati, A.; Mortazavi, M.; Zarch, H.H.; Javidi, M.; Bidokhty, H.A.

    2011-01-01

    A hermetic seal of the root canal space following canal preparation is important in endodontics. This study evaluated the effect of canal curve on adaptation of gutta-percha to dentinal walls of canals obturated using the Herofill system. For this in vitro study, 80 mesial roots of mature human first molars with length of 16 mm, curve between 5 deg and 45 deg, and no caries or resorption of the root surface were selected. A cone beam computed tomography system was used to evaluate the presence or absence of a gap in the samples. Photographs were taken in three sections: 2 mm above the curve, at the curve and 2 mm below the curve. The gap area was identified using Photoshop and AutoCAD software. Kruskal Wallis and Mann-Whitney tests were used to analyze the data mounted in a castcurve. There were significant differences between the two lateral condensation groups with various curves; roots with more curve had more gaps. When the Herofill and lateral condensation groups were compared without considering the sections and curve, there was a significant difference between these groups and the Herofill group had less gaps. The Herofill system is an alternative to the lateral condensation technique in severely curved canals. (author)

  17. Comparison of Curved Root Canals Prepared with Various Chelating Agents

    Science.gov (United States)

    2012-06-01

    aqueous base (11). According to Bramante and Betti, instrumentation with NiTi hand files using EDTA caused greater deviation of the root canal from...15. Peters OA, Peters CI, Schonenberger K, Barbakow F. ProTaper rotary root canal preparation: effects of canal anatomy on final shape analysed by

  18. Flowing equation gradually varied in rectangles channels on depth curve; Ecuacion del flujo gradualmente variado en canales rectangulares de fondo curvo

    Energy Technology Data Exchange (ETDEWEB)

    Sotelo-Avila, G.; Gallegos-Silva, J. [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)

    2002-03-01

    The study of channel flow usually have its basis in the hydrostatic distribution of pressure and the rectilinear flow hypotheses. It is from this hypothesis that the main flow equations are obtained. However, this is not applicable to a vertically curved flow that is present in a curved bed channel. This kind of channel is used to join two different slopes or in ski jumps. This kind of flow presents several changes from the rectilinear flow as in the velocity and pressure distributions and even in the energy loses. The authors of this article propose an equation of gradually varied flow for vertically-curved bed rectangular channels that adds a coefficient to modify the velocity in the calculus of the local friction gradient. With these results is possible now to analyze flow profiles in vertically-curved bed channels where before were used the methods for straight channels and therefore, increase accuracy. [Spanish] Las hipotesis del movimiento rectilineo y de distribucion hidrostatica de la presion son ciertamente las mas importantes en la hidraulica de canales, y de ellas se derivan los principales modelos de flujo que usualmente emplean. Sin embargo, no es valido aplicar la misma hipotesis y metodos de analisis al flujo curvilineo, que ocurre cuando el canal adopta curvaturas verticales en el fondo, las cuales inducen cambios importantes en la distribucion de la velocidad, presion y hasta en la perdida d energia. Tal es el caso de canales que contienen curvas verticales para unir tramos de distintas pendientes y producir el cambio en la direccion del flujo en cubetas deflectoras y vertedores en tunel. Los autores de este articulo proponen una ecuacion de flujo gradualmente variado en canales rectangulares de fondo curvo, esta es de gran utilidad en la determinacion del perfil del flujo con dichas caracteristicas, donde se plantea la adicion de un factor de amplificacion de la velocidad en el calculo del gradiente local de friccion, para tomar en cuenta el

  19. Efficacy of protaper next and protaper universal retreatment systems in removing gutta-percha in curved root canals during root canal retreatment.

    Science.gov (United States)

    Ozyurek, Taha; Ozsezer-Demiryurek, Ebru

    2017-01-01

    The aim of this study was to compare the cleanliness of root canal walls after retreatment using ProTaper Next (PTN), ProTaper Universal Retreatment (PTR) nickel-titanium (NiTi) systems and Hedström hand files in curved mesial canals of mandibular molar teeth and the time required for gutta-percha and sealer removal. Ninety mandibular molar teeth with curved mesial roots were instrumented up to #35.04 with Mtwo NiTi rotary instruments and obturated using the continuous wave of condensation technique. Removal of gutta-percha and sealer was performed using one of the following: PTN and PTR NiTi systems and Hedström hand files. Samples were placed on the VistaScan phosphor plates in the mesio-distal direction and the radiographs were taken. The digital radiographs were analyzed using AutoCAD software. Also, the total time required for gutta-percha removal was calculated by a chronometer. The total retreatment time was significantly shorter in the PTN and PTR groups compared with the manual group (p<0.05). There was a significant difference between the groups according to the total residual gutta-percha and sealer (p<0.05). The PTN and PTR groups left significantly less gutta-percha and sealer remnant than the manual group (p<0.001). Within the limitations of this study, the PTN and PTR groups showed less residual gutta-percha and sealer than the manual group. The NiTi rotary systems were significantly faster than the manual group in the time required for gutta-percha and sealer removal.

  20. Measurement and visualization of file-to-wall contact during ultrasonically activated irrigation in simulated canals

    NARCIS (Netherlands)

    Boutsioukis, C.; Verhaagen, B.; Walmsley, A.D.; Versluis, Michel; van der Sluis, L.W.M.

    2013-01-01

    Aim (i) To quantify in a simulated root canal model the file-to-wall contact during ultrasonic activation of an irrigant and to evaluate the effect of root canal size, file insertion depth, ultrasonic power, root canal level and previous training, (ii) To investigate the effect of file-to-wall

  1. Measurement and visualization of file-to-wall contact during ultrasonically activated irrigation in simulated canals

    NARCIS (Netherlands)

    Boutsioukis, C.; Verhaagen, B.; Walmsley, A. D.; Versluis, M.; van der Sluis, L. W. M.

    2013-01-01

    Aim(i) To quantify in a simulated root canal model the file-to-wall contact during ultrasonic activation of an irrigant and to evaluate the effect of root canal size, file insertion depth, ultrasonic power, root canal level and previous training, (ii) To investigate the effect of file-to-wall

  2. A Comparison of Apical Transportation in Severely Curved Canals Induced by Reciproc and BioRaCe Systems.

    Science.gov (United States)

    Nabavizadeh, Mohammadreza; Abbaszadegan, Abbas; Khojastepour, Leila; Amirhosseini, Mohsen; Kiani, Ebrahim

    2014-01-01

    Preserving the apical root structure during cleaning and shaping of the canal has always been a challenge in endodontics particularly when the root canals are curved. The purpose of this in vitro study was to compare the apical transportation induced by the Reciproc and BioRaCe rotary systems in preparing the mesiobuccal root canal of the human maxillary molars. The mesiobuccal canals of sixty extracted maxillary molars with curvature angle of 25˚-35˚ were selected and randomly assigned into two groups. Each canal was prepared by either Reciproc or BioRaCe rotary systems. A double-digital radiographic technique and AutoCAD software were used to compare the apical transportation at 0.5, 1, 2, 3, 4 and 5 mm distances from the working length (WL). The distance between the master apical rotary file and the initial K-file in the superimposed radiographs determined the amount of apical transportation. An independent t-test was used to compare the groups. The statistical significant level was set at 0.05. Apical transportation of the Reciproc group was significantly greater than the BioRaCe group in all distances (P<0.001). The maximum apical transportation occurred in the Reciproc group at 0.5 mm from the WL (0.048±0.0028 mm) and the minimum occurred for BioRaCe at 5 mm from the WL (0.010±0.0005 mm). The Reciproc system produced significantly more apical transportation than the BioRaCe, but this fact does not seem to negatively alter the clinical success or quality of root canal treatment.

  3. Interoceanic canal excavation scheduling via computer simulation

    Energy Technology Data Exchange (ETDEWEB)

    Baldonado, Orlino C [Holmes and Narver, Inc., Los Angeles, CA (United States)

    1970-05-15

    The computer simulation language GPSS/360 was used to simulate the schedule of several nuclear detonation programs for the interoceanic canal project. The effects of using different weather restriction categories due to air blast and fallout were investigated. The effect of increasing the number of emplacement and stemming crews and the effect of varying the reentry period after detonating a row charge or salvo were also studied. Detonation programs were simulated for the proposed Routes 17A and 25E. The study demonstrates the method of using computer simulation so that a schedule and its associated constraints can be assessed for feasibility. Since many simulation runs can be made for a given set of detonation program constraints, one readily obtains an average schedule for a range of conditions. This provides a method for analyzing time-sensitive operations so that time and cost-effective operational schedules can be established. A comparison of the simulated schedules with those that were published shows them to be similar. (author)

  4. Interoceanic canal excavation scheduling via computer simulation

    International Nuclear Information System (INIS)

    Baldonado, Orlino C.

    1970-01-01

    The computer simulation language GPSS/360 was used to simulate the schedule of several nuclear detonation programs for the interoceanic canal project. The effects of using different weather restriction categories due to air blast and fallout were investigated. The effect of increasing the number of emplacement and stemming crews and the effect of varying the reentry period after detonating a row charge or salvo were also studied. Detonation programs were simulated for the proposed Routes 17A and 25E. The study demonstrates the method of using computer simulation so that a schedule and its associated constraints can be assessed for feasibility. Since many simulation runs can be made for a given set of detonation program constraints, one readily obtains an average schedule for a range of conditions. This provides a method for analyzing time-sensitive operations so that time and cost-effective operational schedules can be established. A comparison of the simulated schedules with those that were published shows them to be similar. (author)

  5. EFFICACY OF PROTAPER NEXT AND PROTAPER UNIVERSAL RETREATMENT SYSTEMS IN REMOVING GUTTA-PERCHA IN CURVED ROOT CANALS DURING ROOT CANAL RETREATMENT

    Directory of Open Access Journals (Sweden)

    Taha ÖZYÜREK

    2017-04-01

    Full Text Available Purpose: The aim of this study was to compare the cleanliness of root canal walls after retreatment using ProTaper Next (PTN, ProTaper Universal Retreatment (PTR nickel-titanium (NiTi systems and Hedström hand files in curved mesial canals of mandibular molar teeth and the time required for gutta-percha and sealer removal. Materials and Methods: Ninety mandibular molar teeth with curved mesial roots were instrumented up to #35.04 with Mtwo NiTi rotary instruments and obturated using the continuous wave of condensation technique. Removal of gutta-percha and sealer was performed using one of the following: PTN and PTR NiTi systems and Hedström hand files. Samples were placed on the VistaScan phosphor plates in the mesio-distal direction and the radiographs were taken. The digital radiographs were analyzed using AutoCAD software. Also, the total time required for gutta-percha removal was calculated by a chronometer. Results: The total retreatment time was significantly shorter in the PTN and PTR groups compared with the manual group (p<0.05. There was a significant difference between the groups according to the total residual gutta-percha and sealer (p<0.05. The PTN and PTR groups left significantly less gutta-percha and sealer remnant than the manual group (p<0.001. Conclusion: Within the limitations of this study, the PTN and PTR groups showed less residual gutta-percha and sealer than the manual group. The NiTi rotary systems were significantly faster than the manual group in the time required for gutta-percha and sealer removal.

  6. Micro-Computed Tomography Evaluation of ProTaper Next and BioRace Shaping Outcomes in Maxillary First Molar Curved Canals.

    Science.gov (United States)

    Pasqualini, Damiano; Alovisi, Mario; Cemenasco, Andrea; Mancini, Lucia; Paolino, Davide Salvatore; Bianchi, Caterina Chiara; Roggia, Andrea; Scotti, Nicola; Berutti, Elio

    2015-10-01

    The aim of this micro-computed tomography study was to describe the shaping properties of ProGlider/ProTaper Next (PG/PTN) and ScoutRace/BioRace (SR/BR) nickel-titanium rotary systems. Thirty maxillary first permanent molars were selected. Mesiobuccal canals were randomly assigned (n = 15) to PG/PTN or SR/BR groups. Irrigation was performed with 5% NaOCl and 10% EDTA. Specimens were scanned (voxel size, 9.1 μm) for matching volumes and surface areas and post-treatment analyses. Root canal centering ability, canal geometry enlargement, and thickness of dentinal wall at inner curvature were assessed at apical level and point of maximum curvature. Results were analyzed with 4 one-way analyses of variance. Canal centering ability was superior in PG/PTN (P = .006 at apical level, P = .025 at point of maximum curvature). PG/PTN demonstrated a more conservative increase of canal areas (P = .027 at apical level, P = .038 at point of maximum curvature). Centrifugal increase in canal diameters did not significantly differ between groups (P = .65 at apical level, P = .61 at point of maximum curvature). Inner dentinal wall thickness was less reduced with PG/PTN compared with SR/BR, with no statistical differences (P = .23 at point of maximum curvature, P = .89 at apical level). PG/PTN shaping taper ranged between 6% and 7%. Neither system produced significant shaping errors in curved canals. PG/PTN system showed better preservation of canal anatomy. PTN offset section did not influence final preparation taper. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  7. Effectiveness of four different final irrigation activation techniques on smear layer removal in curved root canals : a scanning electron microscopy study.

    Directory of Open Access Journals (Sweden)

    Puneet Ahuja

    2014-02-01

    Full Text Available The aim of this study was to assess the efficacy of apical negative pressure (ANP, manual dynamic agitation (MDA, passive ultrasonic irrigation (PUI and needle irrigation (NI as final irrigation activation techniques for smear layer removal in curved root canals.Mesiobuccal root canals of 80 freshly extracted maxillary first molars with curvatures ranging between 25° and 35° were used. A glide path with #08-15 K files was established before cleaning and shaping with Mtwo rotary instruments (VDW, Munich, Germany up to size 35/0.04 taper. During instrumentation, 1 ml of 2.5% NaOCl was used at each change of file. Samples were divided into 4 equal groups (n=20 according to the final irrigation activation technique: group 1, apical negative pressure (ANP (EndoVac; group 2, manual dynamic agitation (MDA; group 3, passive ultrasonic irrigation (PUI; and group 4, needle irrigation (NI. Root canals were split longitudinally and subjected to scanning electron microscopy. The presence of smear layer at coronal, middle and apical levels was evaluated by superimposing 300-μm square grid over the obtained photomicrographs using a four-score scale with X1,000 magnification.Amongst all the groups tested, ANP showed the overall best smear layer removal efficacy (p < 0.05. Removal of smear layer was least effective with the NI technique.ANP (EndoVac system can be used as the final irrigation activation technique for effective smear layer removal in curved root canals.

  8. Vertical Root Fracture initiation in curved roots after root canal preparation: A dentinal micro-crack analysis with LED transillumination.

    Science.gov (United States)

    Miguéns-Vila, Ramón; Martín-Biedma, Benjamín; Varela-Patiño, Purificación; Ruíz-Piñón, Manuel; Castelo-Baz, Pablo

    2017-10-01

    One of the causative factors of root defects is the increased friction produced by rotary instrumentation. A high canal curvature may increase stress, making the tooth more susceptible to dentinal cracks. The purpose of this study was to evaluate dentinal micro-crack formation with the ProTaper NEXT and ProTaper Universal systems using LED transillumination, and to analyze the micro-crack generated at the point of maximum canal curvature. 60 human mandibular premolars with curvatures between 30-49° and radii between 2-4 mm were used. The root canals were instrumented using the Protaper Universal® and Protaper NEXT® systems, with the aid of the Proglider® system. The obtained samples were sectioned transversely before subsequent analysis with LED transillumination at 2 mm and 8 mm from the apex and at the point of maximum canal curvature. Defects were scored: 0 for no defects; and 1 for micro-cracks. Root defects were not observed in the control group. The ProTaper NEXT system caused fewer defects (16.7%) than the ProTaper Universal system (40%) ( P Universal system caused significantly more micro-cracks at the point of maximum canal curvature than the ProTaper NEXT system ( P Universal system. A higher prevalence of defects was found at the point of maximum curvature in the ProTaper Universal group. Key words: Curved root, Micro-crack, point of maximum canal curvature, ProTaper NEXT, ProTaper Universal, Vertical root fracture.

  9. Comparative evaluation of cyclic fatigue resistance of D-RaCe and ProTaper retreatment instruments in curved artificial canals.

    Science.gov (United States)

    Topçuoğlu, H S; Topçuoğlu, G; Aktı, A

    2016-06-01

    To compare the cyclic fatigue resistance of D-RaCe and ProTaper rotary nickel-titanium (NiTi) retreatment files when used in curved artificial canals. A total of 120 new D-RaCe DR2 and ProTaper D3 retreatment files were tested in stainless steel artificial canals having 45° and 60° angles of curvature. Thirty instruments of each of the file systems were tested in both angles of curvature (n = 30). The retreatment instruments were rotated until fracture to calculate the number of cycles to failure. The length of each fractured fragment was recorded. Data were analysed by independent sample t-test. Fractured surfaces of the instruments were analysed by scanning electron microscopy. In the canal with 45° angle of curvature, no significant difference was observed between the retreatment systems (P > 0.05); on the other hand, in the canal with 60° angle of curvature, D-RaCe DR2 instruments had greater cyclic fatigue resistance than ProTaper D3 (P  0.05). The fracture surfaces of the instruments had morphologic characteristics of ductile fracture. D-RaCe DR2 instrument exhibited greater cyclic fatigue resistance than ProTaper D3 only in root canals with 60° angle of curvature. © 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  10. Efficacy of reciprocating and rotary NiTi instruments for retreatment of curved root canals assessed by micro-CT.

    Science.gov (United States)

    Rödig, T; Reicherts, P; Konietschke, F; Dullin, C; Hahn, W; Hülsmann, M

    2014-10-01

    To compare the efficacy of reciprocating and rotary NiTi-instruments in removing filling material from curved root canals using micro-computed tomography. Sixty curved root canals were prepared and filled with gutta-percha and sealer. After determination of root canal curvatures and radii in two directions as well as volumes of filling material, the teeth were assigned to three comparable groups (n = 20). Retreatment was performed using Reciproc, ProTaper Universal Retreatment or Hedström files. Percentages of residual filling material and dentine removal were assessed using micro-CT imaging. Working time and procedural errors were recorded. Statistical analysis was performed by variance procedures. No significant differences amongst the three retreatment techniques concerning residual filling material were detected (P > 0.05). Hedström files removed significantly more dentine than ProTaper Universal Retreatment (P  0.05). Reciproc and ProTaper Universal Retreatment were significantly faster than Hedström files (P = 0.0001). No procedural errors such as instrument fracture, blockage, ledging or perforation were detected for Hedström files. Three perforations were recorded for ProTaper Universal Retreatment, and in both NiTi groups, one instrument fracture occured. Remnants of filling material were observed in all samples with no significant differences between the three techniques. Hedström files removed significantly more dentine than ProTaper Universal Retreatment, but no significant differences between both NiTi systems were detected. Procedural errors were observed with ProTaper Universal Retreatment and Reciproc. © 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  11. Radiographic evaluation of the course and visibility of the mandibular canal

    International Nuclear Information System (INIS)

    Jung, Yun Hoa; Cho, Bong Hae

    2014-01-01

    This study was performed to investigate the course of the mandibular canal on panoramic radiography and the visibility of this canal on both panoramic radiography and cone-beam computed tomography (CBCT). The study consisted of panoramic radiographs and CBCT images from 262 patients. The course of the mandibular canal, as seen in panoramic radiographs, was classified into four types: linear, elliptical, spoon-shaped, and turning curves. The visibility of this canal from the first to the third molar region was evaluated by visually determining whether the mandibular canal was clearly visible, probably visible, or invisible. The visibility of the canal on panoramic radiographs was compared with that on CBCT images. Elliptical curves were most frequently observed along the course of the mandibular canal. The percentage of clearly visible mandibular canals was the highest among the spoon-shaped curves and the lowest among the linear curves. On panoramic radiographs, invisible mandibular canals were found in 22.7% of the examined sites in the first molar region, 11.8% in the second molar region, and 1.3% in the third molar region. On CBCT cross-sectional images, the mandibular canal was invisible in 8.2% of the examined sites in the first molar region, 5.7% in the second molar region, and 0.2% in the third molar region. The visibility of this canal was lower in the first molar region than in the third molar region. The mandibular canal presented better visibility on CBCT images than on panoramic radiographs.

  12. Measurement and visualization of file-to-wall contact during ultrasonically activated irrigation in simulated canals.

    Science.gov (United States)

    Boutsioukis, C; Verhaagen, B; Walmsley, A D; Versluis, M; van der Sluis, L W M

    2013-11-01

    (i) To quantify in a simulated root canal model the file-to-wall contact during ultrasonic activation of an irrigant and to evaluate the effect of root canal size, file insertion depth, ultrasonic power, root canal level and previous training, (ii) To investigate the effect of file-to-wall contact on file oscillation. File-to-wall contact was measured during ultrasonic activation of the irrigant performed by 15 trained and 15 untrained participants in two metal root canal models. Results were analyzed by two 5-way mixed-design anovas. The level of significance was set at P root canal (P root canal (P irrigant activation. Therefore, the term 'Passive Ultrasonic Irrigation' should be amended to 'Ultrasonically Activated Irrigation'. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  13. Histological evaluation of the cleaning effectiveness of two reciprocating single-file systems in severely curved root canals: Reciproc versus WaveOne.

    Science.gov (United States)

    Carvalho, Maira de Souza; Junior, Emílio Carlos Sponchiado; Bitencourt Garrido, Angela Delfina; Roberti Garcia, Lucas da Fonseca; Franco Marques, André Augusto

    2015-01-01

    The aim of this study was to evaluate the cleaning effectiveness achieved with two reciprocating single-file systems in severely curved root canals: Reciproc and WaveOne. Twenty-five mesial roots of mandibular molars were randomly separated into two groups, according to the instrumentation system used. The negative control group consisted of five specimens that were not instrumented. The mesial canals (buccal and lingual) in Reciproc Group were instrumented with file R25 and the WaveOne group with the Primary file. The samples were submitted to histological processing and analyzed under a digital microscope. The WaveOne group presented a larger amount of debris than the Reciproc Group, however, without statistically significant difference (P > 0.05). A larger amount of debris in the control group was observed, with statistically significant difference to Reciproc and WaveOne groups (P file instrumentation systems presented similar effectiveness for root canal cleaning.

  14. A comparative evaluation of the increase in root canal surface area and canal transportation in curved root canals by three rotary systems: A cone-beam computed tomographic study

    Science.gov (United States)

    Prasanthi, Nalam NVD; Rambabu, Tanikonda; Sajjan, Girija S; Varma, K Madhu; Satish, R Kalyan; Padmaja, M

    2016-01-01

    Aim: The aim of this study was to measure the increase in root canal surface area and canal transportation after biomechanical preparation at 1, 3, and 5 mm short of the apex with three different rotary systems in both continuous rotary and reciprocating rotary motions. Materials and Methods: Sixty freshly extracted human mandibular molars with mesial root canal curvatures between 20° and 30° were included in the study. Teeth were randomly distributed into three groups (n = 20). Biomechanical preparations were done in all the mesial canals. In Group 1, instrumentation was done with ProTaper universal rotary files, Group 2, with K3XF rotary files, and Group 3, with LSX rotary files. Each group was further subdivided into subgroups A and B (n = 10) where instrumentation was done by continuous rotary and reciprocating rotary techniques, respectively. Increase in root canal surface area and canal transportation was measured using the preoperative and postoperative cone-beam computed tomography scans. Statistical Analysis: The data were analyzed by one-way ANOVA followed by Tukey pairwise multiple comparison tests. Results: Increase in root canal surface area was significantly more (P 0.05) in increase of root canal surface area and canal transportation between continuous rotary and reciprocating rotary techniques for ProTaper Universal, K3XF and LSX groups. Conclusion: LSX rotary system showed minimal increase of root canal surface area and minimal canal transportation when compared to ProTaper and K3XF rotary systems. PMID:27656062

  15. Shaping ability of 4 different single-file systems in simulated S-shaped canals.

    Science.gov (United States)

    Saleh, Abdulrahman Mohammed; Vakili Gilani, Pouyan; Tavanafar, Saeid; Schäfer, Edgar

    2015-04-01

    The aim of this study was to compare the shaping ability of 4 different single-file systems in simulated S-shaped canals. Sixty-four S-shaped canals in resin blocks were prepared to an apical size of 25 using Reciproc (VDW, Munich, Germany), WaveOne (Dentsply Maillefer, Ballaigues, Switzerland), OneShape (Micro Méga, Besançon, France), and F360 (Komet Brasseler, Lemgo, Germany) (n = 16 canals/group) systems. Composite images were made from the superimposition of pre- and postinstrumentation images. The amount of resin removed by each system was measured by using a digital template and image analysis software. Canal aberrations and the preparation time were also recorded. The data were statistically analyzed by using analysis of variance, Tukey, and chi-square tests. Canals prepared with the F360 and OneShape systems were better centered compared with the Reciproc and WaveOne systems. Reciproc and WaveOne files removed significantly greater amounts of resin from the inner side of both curvatures (P files was significantly faster compared with WaveOne and F360 files (P file instruments were safe to use and were able to prepare the canals efficiently. However, single-file systems that are less tapered seem to be more favorable when preparing S-shaped canals. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  16. Shaping ability of NT Engine and McXim rotary nickel-titanium instruments in simulated root canals. Part 1.

    Science.gov (United States)

    Thompson, S A; Dummer, P M

    1997-07-01

    The aim of this study was to determine the shaping ability of NT Engine and McXim nickel-titanium rotary instruments in simulated root canals. In all, 40 canals consisting of four different shapes in terms of angle and position of curvature were prepared by a combination of NT Engine and McXim instruments using the technique recommended by the manufacturer. Part 1 of this two-part report describes the efficacy of the instruments in terms of preparation time, instrument failure, canal blockages, loss of canal length and three-dimensional canal form. Overall, the mean preparation time for all canals was 6.01 min, with canal shape having a significant effect (P Engine and McXim instruments prepared canals rapidly, with few deformations, no canal blockages and with minimal change in working length. The three-dimensional form of the canals demonstrated good flow and taper characteristics.

  17. Using residual tritiated water from Cernavoda NPP to study Danube - Black Sea Canal hydrodynamics

    International Nuclear Information System (INIS)

    Varlam, C.; Stefanescu, I.; Lazar, R.; Varlam, M.; Patrascu, V.; Bucur, C.; Bobric, E.

    2003-01-01

    By benefiting of Cernavoda NPP's location in the neighbourhood of Danube - Black Sea Canal one suggests extending the area of interest along this canal particularly to use the residual tritiated water from this CANDU type reactor as tracing means in the study of canal's hydrodynamics. This canal appears to be ideal for such a study because releases in normal operation of NPP are occasional. The tritiated water can be used for simulating the transport and dispersion of soluble pollutants because it has the same physical characteristics as the usual water. By measuring response curves produced at injecting a known amount of tracer one can developed an efficient method for estimating: the soluble pollutant velocity along the canal; attenuation rate of concentration peak as a function of time as well as the time required by the propagation front of the soluble pollutant to reach a given point along the canal. In this work the calculation of the mixture length as a function of the particular characteristics of the canal is presented as well as different experimental formulas. Also the reference level of tritium concentration in the investigated area is established for future experiments

  18. Using commercial simulators for determining flash distillation curves for petroleum fractions

    Directory of Open Access Journals (Sweden)

    Eleonora Erdmann

    2008-01-01

    Full Text Available This work describes a new method for estimating the equilibrium flash vaporisation (EFV distillation curve for petro-leum fractions by using commercial simulators. A commercial simulator was used for implementing a stationary mo-del for flash distillation; this model was adjusted by using a distillation curve obtained from standard laboratory ana-lytical assays. Such curve can be one of many types (eg ASTM D86, D1160 or D2887 and involves an experimental procedure simpler than that required for obtaining an EFV curve. Any commercial simulator able to model petroleum can be used for the simulation (HYSYS and CHEMCAD simulators were used here. Several types of petroleum and fractions were experimentally analysed for evaluating the proposed method; this data was then put into a process si-mulator (according to the proposed method to estimate the corresponding EFV curves. HYSYS- and CHEMCAD-estimated curves were compared to those produced by two traditional estimation methods (Edmister’s and Maswell’s methods. Simulation-estimated curves were close to average Edmister and Maxwell curves in all cases. The propo-sed method has several advantages; it avoids the need for experimentally obtaining an EFV curve, it does not de-pend on the type of experimental curve used to fit the model and it enables estimating several pressures by using just one experimental curve as data.

  19. [Glide path management of rotary nickel-titanium instruments in simulated root canals].

    Science.gov (United States)

    Han, Y; Bai, Y H; Hou, X M

    2018-02-18

    To compare the shaping ability of ProGlider, HyFlex EDM Glidepath File and RaCe ISO 10 with that of PathFile and stainless steel K-file hand instruments in simulated root canals. A total of 60 simulated resin blocks were divided randomly into five groups (n=12), each group prepared with each instrument, respectively. Preparation time was recorded. Pre- and post-operative images were obtained using a scanner and superimposed using Photoshop. The material removal from the inner and outer canal walls beginning from 0 mm at the end point of the canal were measured using ImageJ. Centering ability was determined, accordingly. The data were analyzed using the One-Way ANOVA at a significance level of P0.05). The removal of resin from the outer wall at the apical portion was significantly lower for HyFlex EDM Glidepath File than for ProGlider (PEDM Glidepath File the second most, and the other 3 groups among the same levels. As far as the centering ability was concerned, at the apical portion, HyFlex EDM Glidepath File was the best, ProGlider the second best, no significant difference identified among the other 3 groups. At the curvature portion, ProGlider and HyFlex EDM Glidepath File were the best, PathFile the second, RaCe ISO 10 the third, the worst was the SS K-file. At the straight portion, the difference amongt the 5 groups was not significant. The shaping abilities of ProGlider, HyFlex EDM Glidepath File and RaCe ISO 10 were better or comparable to that of PathFile, while the preparation time for ProGlider reduced significantly, and HyFlex EDM Glidepath File and RaCe ISO 10 removed significantly more resin at the straight portion of the canal.

  20. Root canal shaping using rotary nickel-titanium files in preclinical dental education in Turkey.

    Science.gov (United States)

    Ünal, Gül Çelik; Maden, Murat; Orhan, Ekim Onur; Sarıtekin, Erdal; Teke, Anıl

    2012-04-01

    The purposes of this study were to evaluate the ability of a group of third-year dental students without any endodontic clinical experience to use the ProTaper Instruments (Dentsply Maillefer) to decrease the amount of straightening of curved canals on human molar teeth and to determine the incidence of instrument fractures and instrumentation time. Thirty-one undergraduate dental students in Turkey received a training session. The students prepared a total of 144 root canals in human mandibular or maxillary molar teeth with ProTaper. Fifty-six teeth were excluded due to unreadable image, misinformation, or straight or severe curve. Using pre- and post-preparation digital radiographs, the straightening of curved root canals was investigated. Loss of working length and incidence of fracture were also noted. A total of eighty-eight curved root canals were selected. Mesiobuccal or mesiolingual roots with curvatures of between 20° and 43° as assessed by Schneider's method and working length of between 15 mm and 22.5 mm were included in the study. The means of the curved root canals before and after the instrumentation were 29.5° ± 6° and 27° ± 6.3°, respectively. The means of the working length before and after the instrumentation were 19 mm ± 2.1 mm and 18.3 mm ± 1.9 mm, respectively. A statistically significant difference between straightening of curved root canals and loss of working length was found between before and after instrumentation (psession.

  1. Scanning Electron Microscopic Evaluation of Residual Smear Layer Following Preparation of Curved Root Canals Using Hand Instrumentation or Two Engine-Driven Systems.

    Science.gov (United States)

    Khademi, Abbasali; Saatchi, Masoud; Shokouhi, Mohammad Mehdi; Baghaei, Badri

    2015-01-01

    In this experimental study, the amount of smear layer (SL) remnants in curved root canals after chemomechanical instrumentation with two engine-driven systems or hand instrumentation was evaluated. Forty-eight mesiobuccal roots of mandibular first molars with curvatures ranging between 25 and 35 degrees (according to Schneider's method) were divided into three groups (n=16) which were prepared by either the ProTaper Universal file series, Reciproc single file system or hand instrumentation. The canals were intermittently irrigated with 5.25% NaOCl and 17% (ethylenediaminetetraacetic acid) EDTA, followed by distilled water as the final rinse. The roots were split longitudinally and the apical third of the specimens were evaluated under 2500× magnification with a scanning electron microscope (SEM). The mean scores of the SL were calculated and analyzed using the non-parametric Kruskal-Wallis and Mann-Whitney U tests. The mean scores of the SL were 2.00±0.73, 1.94±0.68 and 1.44±0.63 µm for the ProTaper Universal, Reciproc and hand instrumentation, respectively. Mean score of SL was significantly less in the hand instrumentation group than the ProTaper (P=0.027) and Reciproc (P=0.035) groups. The difference between the two engine-driven systems, however, was not significant (P=0.803). The amount of smear layer in the apical third of curved root canals prepared with both engine-driven systems was similar and greater than the hand instrumentation technique. Complete cleanliness was not attained.

  2. Applying tracer techniques to NPP liquid effluents for estimating the maximum concentration of soluble pollutants in a man-made canal

    International Nuclear Information System (INIS)

    Varlam, Carmen; Stefanescu, Ioan; Varlam, Mihai; Raceanu, Mircea; Enache, Adrian; Faurescu, Ionut; Patrascu, Vasile; Bucur, Cristina

    2006-01-01

    Full text: The possibility of a contamination agent being accidentally or intentionally spilled upstream from a water supply is a constant concern to those diverting and using water from a channel. A method of rapidly estimating the travel-time or dispersion is needed for pollution control or warning system on channels where data are scarce. Travel-time and mixing of water within a stream are basic streamflow characteristics needed in order to predict the rate of movement and dilution of pollutants that could be introduced in the stream. In this study we propose using tritiated liquid effluents from CANDU type nuclear power plant as a tracer, to study hydrodynamics on Danube-Black Sea Canal. This canal is ideal for this kind of study, because wastewater evacuations occur occasionally due to technical operations of nuclear power plant. Tritiated water can be used to simulate the transport and dispersion of solutes in Danube-Black Sea Canal because they have the same physical characteristics as the water. Measured tracer-response curves produced from injection of a known amount of soluble tracer provide an efficient method of obtaining the necessary data. This method can estimate: (1) the rate of movement of a solute through the canal reach: (2) the rate of peak attenuation concentration of a conservative solute in time; and (3) the length of time required for the solute plume to pass a point in the canal. This paper presents the mixing length calculation for particular conditions (lateral branch of the canal, and lateral injection of wastewater from the nuclear power plant). A study of published experimentally-obtained formulas was used to determine proper mixing length. Simultaneous measurements in different locations of the canal confirm the beginning of the experiment. Another result used in a further experiment concerns the tritium level along the Danube-Black Sea Canal. We measured tritium activity concentration in water sampled along the Canal between July

  3. 3D Analysis of D-RaCe and Self-Adjusting File in Removing Filling Materials from Curved Root Canals Instrumented and Filled with Different Techniques

    Directory of Open Access Journals (Sweden)

    Neslihan Simsek

    2014-01-01

    Full Text Available The aim of this study was to compare the efficacy of D-RaCe files and a self-adjusting file (SAF system in removing filling material from curved root canals instrumented and filled with different techniques by using microcomputed tomography (micro-CT. The mesial roots of 20 extracted mandibular first molars were used. Root canals (mesiobuccal and mesiolingual were instrumented with SAF or Revo-S. The canals were then filled with gutta-percha and AH Plus sealer using cold lateral compaction or thermoplasticized injectable techniques. The root fillings were first removed with D-RaCe (Step 1, followed by Step 2, in which a SAF system was used to remove the residual fillings in all groups. Micro-CT scans were used to measure the volume of residual filling after root canal filling, reinstrumentation with D-RaCe (Step 1, and reinstrumentation with SAF (Step 2. Data were analyzed using Wilcoxon and Kruskal-Wallis tests. There were no statistically significant differences between filling techniques in the canals instrumented with SAF (P=0.292 and Revo-S (P=0.306. The amount of remaining filling material was similar in all groups (P=0.363; all of the instrumentation techniques left filling residue inside the canals. However, the additional use of SAF was more effective than using D-RaCe alone.

  4. The Predictive Value of Ultrasound Learning Curves Across Simulated and Clinical Settings

    DEFF Research Database (Denmark)

    Madsen, Mette E; Nørgaard, Lone N; Tabor, Ann

    2017-01-01

    OBJECTIVES: The aim of the study was to explore whether learning curves on a virtual-reality (VR) sonographic simulator can be used to predict subsequent learning curves on a physical mannequin and learning curves during clinical training. METHODS: Twenty midwives completed a simulation-based tra......OBJECTIVES: The aim of the study was to explore whether learning curves on a virtual-reality (VR) sonographic simulator can be used to predict subsequent learning curves on a physical mannequin and learning curves during clinical training. METHODS: Twenty midwives completed a simulation......-based training program in transvaginal sonography. The training was conducted on a VR simulator as well as on a physical mannequin. A subgroup of 6 participants underwent subsequent clinical training. During each of the 3 steps, the participants' performance was assessed using instruments with established...... settings. RESULTS: A good correlation was found between time needed to achieve predefined performance levels on the VR simulator and the physical mannequin (Pearson correlation coefficient .78; P VR simulator correlated well to the clinical performance scores (Pearson...

  5. CANAL code

    International Nuclear Information System (INIS)

    Gara, P.; Martin, E.

    1983-01-01

    The CANAL code presented here optimizes a realistic iron free extraction channel which has to provide a given transversal magnetic field law in the median plane: the current bars may be curved, have finite lengths and cooling ducts and move in a restricted transversal area; terminal connectors may be added, images of the bars in pole pieces may be included. A special option optimizes a real set of circular coils [fr

  6. Comparison of the shaping ability of Twisted Files with ProTaper and RevoS nickel-titanium instruments in simulated canals

    Directory of Open Access Journals (Sweden)

    Cumhur Aydin

    2012-09-01

    Conclusion: According to the results of this study, TFs respected the original canal curvature better than did ProTaper and RevoS rotary NiTi instruments. TF instruments also provided a more-centered apical preparation of the simulated canals at the apical third.

  7. Removal of Gutta-Percha/Zinc-Oxide-Eugenol Sealer or Gutta-Percha/Epoxy Resin Sealer from Severely Curved Canals: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    Santhoshini Reddy

    2011-01-01

    Full Text Available The aim of this study was to compare the cleanliness of root canal walls after retreatment using two rotary retreatment files to hand instruments in severely curved canals obturated with gutta-percha and two different sealers. Single rooted mandibular premolars (n=90 with root curvatures were instrumented and obturated with gutta-percha and an epoxy resin (Group 1, n=45 or zinc oxide eugenol sealer (Group 2, n=45. Following retreatment of the specimens (n=15 ProTaper Universal Retreatment Files (Subgroup B or R-Endo retreatment files (Subgroup C after 1 month, split specimens were examined under a stereomicroscope and the percentage of remaining root filling material was statistically compared using one way ANOVA with Bonferroni adjustment for multiple comparisons (P=0.05. The R-Endo system performed significantly better than the other two file systems (P<0.05. None of the systems used in this study cleaned root canals thoroughly. The R-Endo system did provide cleaner walls when compared to the other instruments used. The type of root filling materials had an impact on the outcomes with all techniques.

  8. Wear of K3 and ProTaper files after simulated clinical use in curved canals

    Directory of Open Access Journals (Sweden)

    Patrícia de Almeida Rodrigues Silva e Souza

    2009-01-01

    Full Text Available Objective: To assess wear, after simulated clinical use of K3 (SybronEndo, Orange, CA, EUA and ProTaper files (Dentsply-Maillefer, Tulsa, Oklahoma, EUA in 46 mesiovestibular roots of human maxillary first molars, recently extracted and with mean angulation of 40°.Methods: The teeth were divided as follows: a K3 (SybronEndo, Orange, CA, EUA (with radial bands and b ProTaper (Dentsply-Maillefer, Tulsa, Oklahoma, EUA (without radial bands. The files were assessed by scanning electronic microscopy before first use to visualize fabrication defects, and after 7 and 13 cycles of debridement in the canals. Debridement with files K3 (SybronEndo, Orange, CA, EUA and ProTaper (Dentsply-Maillefer, Tulsa, Oklahoma, EUA was performed in accordance with the manufacturers’ recommendations. The criteria for wear assessment were: defects (stretching, shortening/spiral inversion, presence of craters, oblique cracks and fracture. After assessment by SEM and before they were used, metal barbs on the crest of the spirals and oblique scratches due to the machining process were found in all the files.Results: In the K3 system (SybronEndo, Orange, CA, USA, after being used seven times, all the instruments showed cutting angle defects,and 25/08 and 25/10 had oblique cracks in the body of the active part leading to ductile fracture after being used for the eighth time. In the ProTaper system (Dentsply-Maillefer, Tulsa, Oklahoma, USA, after being used seven times, in addition to cutting angle defects, the files also presented cracks, and ruptile fracture occurred in F3 during use for the thirteenth time. At the end of preparation, craters were seen along the active part of the files.Conclusion: In the final analysis, it was seen that the system are equivalent with regard to the defects found, irrespective of the active part design,being proportional to the number of cycles of use, and these defects could act as points of greater fragility, favoring fracture.

  9. Comparative study of 6 rotary nickel-titanium systems and hand instrumentation for root canal preparation in severely curved root canals of extracted teeth.

    Science.gov (United States)

    Celik, Davut; Taşdemir, Tamer; Er, Kürşat

    2013-02-01

    Some improvements have been developed with new generations of nickel-titanium (NiTi) rotary instruments that led to their successful and extensive application in clinical practice. The purpose of this in vitro study was to compare the root canal preparations performed by using GT Series X and Twisted File systems produced by innovative manufacturing process with Revo-S, RaCe, Mtwo, and ProTaper Universal systems manufactured directly from conventional nitinol and with stainless steel K-Flexofile instruments. The mesiobuccal root canals of 140 maxillary first permanent molars that had between 30°-40° curvature angle and 4- to 9-mm curvature radius of the root canal were used. After root canal preparations made by using GT Series X, Twisted File, Revo-S, RaCe, Mtwo, and ProTaper Universal NiTi rotary systems and stainless steel K-Flexofile instruments, transportation occurred in the root canal, and alteration of working length (WL) was assessed by using a modified double-digital radiographic technique. The data were compared by the post hoc Tukey honestly significant difference test. NiTi rotary systems caused less canal transportation and alteration of WL than K-Flexofile instruments (P .05) except 2.5 mm from the WL. At this level ProTaper Universal system caused significant canal transportation (P ProTaper Universal rotary systems manufactured by traditional methods. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  10. Some History and Hydrology of the Panama Canal

    National Research Council Canada - National Science Library

    Pabst, Arthur

    2000-01-01

    At the request of the Panama Canal Commission (now Panama Canal Authority), the Hydrologic Engineering Center participated in the development of a model to simulate the existing operation of the Panama Canal System...

  11. Using commercial simulators for determining flash distillation curves for petroleum fractions

    OpenAIRE

    Eleonora Erdmann; Demetrio Humana; Samuel Franco Domínguez; Lorgio Mercado Fuentes

    2010-01-01

    This work describes a new method for estimating the equilibrium flash vaporisation (EFV) distillation curve for petro-leum fractions by using commercial simulators. A commercial simulator was used for implementing a stationary mo-del for flash distillation; this model was adjusted by using a distillation curve obtained from standard laboratory ana-lytical assays. Such curve can be one of many types (eg ASTM D86, D1160 or D2887) and involves an experimental procedure simpler than that required...

  12. Experimental simulation of closed timelike curves.

    Science.gov (United States)

    Ringbauer, Martin; Broome, Matthew A; Myers, Casey R; White, Andrew G; Ralph, Timothy C

    2014-06-19

    Closed timelike curves are among the most controversial features of modern physics. As legitimate solutions to Einstein's field equations, they allow for time travel, which instinctively seems paradoxical. However, in the quantum regime these paradoxes can be resolved, leaving closed timelike curves consistent with relativity. The study of these systems therefore provides valuable insight into nonlinearities and the emergence of causal structures in quantum mechanics--essential for any formulation of a quantum theory of gravity. Here we experimentally simulate the nonlinear behaviour of a qubit interacting unitarily with an older version of itself, addressing some of the fascinating effects that arise in systems traversing a closed timelike curve. These include perfect discrimination of non-orthogonal states and, most intriguingly, the ability to distinguish nominally equivalent ways of preparing pure quantum states. Finally, we examine the dependence of these effects on the initial qubit state, the form of the unitary interaction and the influence of decoherence.

  13. Land Use Management in the Panama Canal Watershed to Maximize Hydrologic Ecosystem Services Benefits: Explicit Simulation of Preferential Flow Paths in an HPC Environment

    Science.gov (United States)

    Regina, J. A.; Ogden, F. L.; Steinke, R. C.; Frazier, N.; Cheng, Y.; Zhu, J.

    2017-12-01

    Preferential flow paths (PFP) resulting from biotic and abiotic factors contribute significantly to the generation of runoff in moist lowland tropical watersheds. Flow through PFPs represents the dominant mechanism by which land use choices affect hydrological behavior. The relative influence of PFP varies depending upon land-use management practices. Assessing the possible effects of land-use and landcover change on flows, and other ecosystem services, in the humid tropics partially depends on adequate simulation of PFP across different land-uses. Currently, 5% of global trade passes through the Panama Canal, which is supplied with fresh water from the Panama Canal Watershed. A third set of locks, recently constructed, are expected to double the capacity of the Canal. We incorporated explicit simulation of PFPs in to the ADHydro HPC distributed hydrological model to simulate the effects of land-use and landcover change due to land management incentives on water resources availability in the Panama Canal Watershed. These simulations help to test hypotheses related to the effectiveness of various proposed payments for ecosystem services schemes. This presentation will focus on hydrological model formulation and performance in an HPC environment.

  14. Simulation of the effects of proposed tide gates on circulation, flushing, and water quality in residential canals, Cape Coral Florida

    Science.gov (United States)

    Goodwin, Carl R.

    1991-01-01

    Decades of dredging and filling of Florida's low-lying coastal wetlands have produced thousands of miles of residential tidal canals and adjacent waterfront property. Typically, these canals are poorly flushed, and over time, accumulated organic-rich bottom materials, contribute to an increasingly severe degraded water quality. One-dimensional hydrodynamic and constituent-transport models were applied to two dead-end canal systems to determine the effects of canal system interconnection using tide gates on water circulation and constituent flushing. The model simulates existing and possible future circulation and flushing conditions in about 29 miles of the approximately 130 miles of tidally influenced canals in Cape Coral, located on the central west coast of peninsular Florida. Model results indicate that tidal water-level differences between the two canal systems can be converted to kinetic energy, in the form of increased water circulation, but the use of one-way tide gate interconnections. Computations show that construction of from one to four tide gates will cause replacement of a volume of water equivalent to the total volume of canals in both systems in 15 to 9 days, respectively. Because some canals flush faster than others, 47 and 21 percent of the original canal water will remain in both systems 50 days after start of operation of one and four tide gates, respectively. Some of the effects that such increased flushing are expected to have include reduced density stratification and associated dissolved-oxygen depletion in canal bottom waters, increased localized reaeration, and more efficient discharge of stormwater runoff entering the canals.

  15. Efficacy of CM-Wire, M-Wire, and Nickel-Titanium Instruments for Removing Filling Material from Curved Root Canals: A Micro-Computed Tomography Study.

    Science.gov (United States)

    Rodrigues, Clarissa Teles; Duarte, Marco Antonio Hungaro; de Almeida, Marcela Milanezi; de Andrade, Flaviana Bombarda; Bernardineli, Norberti

    2016-11-01

    The aim of this ex vivo study was to evaluate the removal of filling material after using CM-wire, M-wire, and nickel-titanium instruments in both reciprocating and rotary motions in curved canals. Thirty maxillary lateral incisors were divided into 9 groups according to retreatment procedures: Reciproc R25 followed by Mtwo 40/.04 and ProDesign Logic 50/.01 files; ProDesign R 25/.06 followed by ProDesign Logic 40/.05 and ProDesign Logic 50/.01 files; and Gates-Glidden drills, Hedström files, and K-files up to apical size 30 followed by K-file 40 and K-file 50 up to the working length. Micro-computed tomography scans were performed before and after each reinstrumentation procedure to evaluate root canal filling removal. Statistical analysis was performed with Kruskal-Wallis, Friedman, and Wilcoxon tests (P < .05). No significant differences in filling material removal were found in the 3 groups of teeth. The use of Mtwo and ProDesign Logic 40/.05 rotary files did not enhance filling material removal after the use of reciprocating files. The use of ProDesign Logic 50/.01 files significantly reduced the amount of filling material at the apical levels compared with the use of reciprocating files. Association of reciprocating and rotary files was capable of removing a large amount of filling material in the retreatment of curved canals, irrespective of the type of alloy of the instruments. The use of a ProDesign Logic 50/.01 file for apical preparation significantly reduced the amount of remnant material in the apical portion when compared with reciprocating instruments. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  16. Efficacy of D-RaCe and ProTaper Universal Retreatment NiTi instruments and hand files in removing gutta-percha from curved root canals - a micro-computed tomography study.

    Science.gov (United States)

    Rödig, T; Hausdörfer, T; Konietschke, F; Dullin, C; Hahn, W; Hülsmann, M

    2012-06-01

    To compare the efficacy of two rotary NiTi retreatment systems and Hedström files in removing filling material from curved root canals. Curved root canals of 57 extracted teeth were prepared using FlexMaster instruments and filled with gutta-percha and AH Plus. After determination of root canal curvatures and radii in two directions, the teeth were assigned to three identical groups (n = 19). The root fillings were removed with D-RaCe instruments, ProTaper Universal Retreatment instruments or Hedström files. Pre- and postoperative micro-CT imaging was used to assess the percentage of residual filling material as well as the amount of dentine removal. Working time and procedural errors were recorded. Data were analysed using analysis of covariance and analysis of variance procedures. D-RaCe instruments were significantly more effective than ProTaper Universal Retreatment instruments and Hedström files (P ProTaper group, four instrument fractures and one lateral perforation were observed. Five instrument fractures were recorded for D-RaCe. D-RaCe instruments were associated with significantly less residual filling material than ProTaper Universal Retreatment instruments and hand files. Hedström files removed significantly less dentine than both rotary NiTi systems. Retreatment with rotary NiTi systems resulted in a high incidence of procedural errors. © 2012 International Endodontic Journal.

  17. Shaping Ability of Reciproc, WaveOne GOLD, and HyFlex EDM Single-file Systems in Simulated S-shaped Canals.

    Science.gov (United States)

    Özyürek, Taha; Yılmaz, Koray; Uslu, Gülşah

    2017-05-01

    The aim of the present study was to compare the shaping ability of Reciproc (RPC; VDW, Munich, Germany), HyFlex EDM (HEDM; Coltene/Whaledent AG, Altstätten, Switzerland), and WaveOne GOLD (WOG; Dentsply Maillefer, Ballaigues, Switzerland) nickel-titanium (NiTi) files made of different NiTi alloys in S-shaped simulated canals. Sixty S-shaped canals in resin blocks were prepared to an apical size of 0.25 mm using RPC R25, WOG Primary, and HEDM OneFile (n = 20 canal/per group) systems. Composite images were made from the superimposition of pre- and postinstrumentation images. The amount of resin removed by each system was measured using a digital template and image analysis software in 22 different points. Canal aberrations were also recorded. Data were statistically analyzed using the Kruskal-Wallis and post hoc Dunn tests at the 5% level. NiTi file fracture was not observed during shaping of the simulated canals although a danger zone formation in 1 sample and a ledge in 1 sample were observed in the RPC group. There was no statistically significant difference between the WOG and HEDM groups' apical, medial, and coronal regions (P > .05). However, it was determined that the RPC group removed a statistically significantly higher amount of resin from all the canal regions when compared with the WOG and HEDM groups (P < .05). Within the limitation of the present study, it was determined that all of the tested NiTi files caused various levels of resin removal. However, WOG and HEDM NiTi files were found to cause a lower level of resin removal than RPC NiTi files. Copyright © 2017 American Association of Endodontists. All rights reserved.

  18. Computed tomography evaluation of rotary systems on the root canal transportation and centering ability

    Directory of Open Access Journals (Sweden)

    André PAGLIOSA

    2015-01-01

    Full Text Available Abstract : The endodontic preparation of curved and narrow root canals is challenging, with a tendency for the prepared canal to deviate away from its natural axis. The aim of this study was to evaluate, by cone-beam computed tomography, the transportation and centering ability of curved mesiobuccal canals in maxillary molars after biomechanical preparation with different nickel-titanium (NiTi rotary systems. Forty teeth with angles of curvature ranging from 20° to 40° and radii between 5.0 mm and 10.0 mm were selected and assigned into four groups (n = 10, according to the biomechanical preparative system used: Hero 642 (HR, Liberator (LB, ProTaper (PT, and Twisted File (TF. The specimens were inserted into an acrylic device and scanned with computed tomography prior to, and following, instrumentation at 3, 6 and 9 mm from the root apex. The canal degree of transportation and centering ability were calculated and analyzed using one-way ANOVA and Tukey’s tests (α = 0.05. The results demonstrated no significant difference (p > 0.05 in shaping ability among the rotary systems. The mean canal transportation was: -0.049 ± 0.083 mm (HR; -0.004 ± 0.044 mm (LB; -0.003 ± 0.064 mm (PT; -0.021 ± 0.064 mm (TF. The mean canal centering ability was: -0.093 ± 0.147 mm (HR; -0.001 ± 0.100 mm (LB; -0.002 ± 0.134 mm (PT; -0.033 ± 0.133 mm (TF. Also, there was no significant difference among the root segments (p > 0.05. It was concluded that the Hero 642, Liberator, ProTaper, and Twisted File rotary systems could be safely used in curved canal instrumentation, resulting in satisfactory preservation of the original canal shape.

  19. Computed tomography evaluation of rotary systems on the root canal transportation and centering ability

    International Nuclear Information System (INIS)

    Pagliosa, Andre; Raucci-Neto, Walter; Silva-Souza, Yara Teresinha Correa; Alfredo, Edson; Sousa-Neto, Manoel Damiao; Versiani, Marco Aurelio

    2015-01-01

    The endodontic preparation of curved and narrow root canals is challenging, with a tendency for the prepared canal to deviate away from its natural axis. The aim of this study was to evaluate, by cone-beam computed tomography, the transportation and centering ability of curved mesiobuccal canals in maxillary molars after biomechanical preparation with different nickel-titanium (NiTi) rotary systems. Forty teeth with angles of curvature ranging from 20° to 40° and radii between 5.0 mm and 10.0 mm were selected and assigned into four groups (n = 10), according to the biomechanical preparative system used: Hero 642 (HR), Liberator (LB), ProTaper (PT), and Twisted File (TF). The specimens were inserted into an acrylic device and scanned with computed tomography prior to, and following, instrumentation at 3, 6 and 9 mm from the root apex. The canal degree of transportation and centering ability were calculated and analyzed using one-way ANOVA and Tukey’s tests (α = 0.05). The results demonstrated no significant difference (p > 0.05) in shaping ability among the rotary systems. The mean canal transportation was: -0.049 ± 0.083 mm (HR); -0.004 ± 0.044 mm (LB); -0.003 ± 0.064 mm (PT); -0.021 ± 0.064 mm (TF). The mean canal centering ability was: -0.093 ± 0.147 mm (HR); -0.001 ± 0.100 mm (LB); -0.002 ± 0.134 mm (PT); -0.033 ± 0.133 mm (TF). Also, there was no significant difference among the root segments (p > 0.05). It was concluded that the Hero 642, Liberator, ProTaper, and Twisted File rotary systems could be safely used in curved canal instrumentation, resulting in satisfactory preservation of the original canal shape. (author)

  20. Computed tomography evaluation of rotary systems on the root canal transportation and centering ability

    Energy Technology Data Exchange (ETDEWEB)

    Pagliosa, Andre; Raucci-Neto, Walter; Silva-Souza, Yara Teresinha Correa; Alfredo, Edson, E-mail: ysousa@unaerp.br [Universidade de Ribeirao Preto (UNAERP), SP (Brazil). Fac. de Odontologia; Sousa-Neto, Manoel Damiao; Versiani, Marco Aurelio [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Fac. de Odoentologia

    2015-03-01

    The endodontic preparation of curved and narrow root canals is challenging, with a tendency for the prepared canal to deviate away from its natural axis. The aim of this study was to evaluate, by cone-beam computed tomography, the transportation and centering ability of curved mesiobuccal canals in maxillary molars after biomechanical preparation with different nickel-titanium (NiTi) rotary systems. Forty teeth with angles of curvature ranging from 20° to 40° and radii between 5.0 mm and 10.0 mm were selected and assigned into four groups (n = 10), according to the biomechanical preparative system used: Hero 642 (HR), Liberator (LB), ProTaper (PT), and Twisted File (TF). The specimens were inserted into an acrylic device and scanned with computed tomography prior to, and following, instrumentation at 3, 6 and 9 mm from the root apex. The canal degree of transportation and centering ability were calculated and analyzed using one-way ANOVA and Tukey’s tests (α = 0.05). The results demonstrated no significant difference (p > 0.05) in shaping ability among the rotary systems. The mean canal transportation was: -0.049 ± 0.083 mm (HR); -0.004 ± 0.044 mm (LB); -0.003 ± 0.064 mm (PT); -0.021 ± 0.064 mm (TF). The mean canal centering ability was: -0.093 ± 0.147 mm (HR); -0.001 ± 0.100 mm (LB); -0.002 ± 0.134 mm (PT); -0.033 ± 0.133 mm (TF). Also, there was no significant difference among the root segments (p > 0.05). It was concluded that the Hero 642, Liberator, ProTaper, and Twisted File rotary systems could be safely used in curved canal instrumentation, resulting in satisfactory preservation of the original canal shape. (author)

  1. Study on the algorithm for Newton-Rapson iteration interpolation of NURBS curve and simulation

    Science.gov (United States)

    Zhang, Wanjun; Gao, Shanping; Cheng, Xiyan; Zhang, Feng

    2017-04-01

    In order to solve the problems of Newton-Rapson iteration interpolation method of NURBS Curve, Such as interpolation time bigger, calculation more complicated, and NURBS curve step error are not easy changed and so on. This paper proposed a study on the algorithm for Newton-Rapson iteration interpolation method of NURBS curve and simulation. We can use Newton-Rapson iterative that calculate (xi, yi, zi). Simulation results show that the proposed NURBS curve interpolator meet the high-speed and high-accuracy interpolation requirements of CNC systems. The interpolation of NURBS curve should be finished. The simulation results show that the algorithm is correct; it is consistent with a NURBS curve interpolation requirements.

  2. Quantitative three-dimensional analysis of root canal curvature in maxillary first molars using micro-computed tomography.

    Science.gov (United States)

    Lee, Jong-Ki; Ha, Byung-Hyun; Choi, Jeong-Ho; Heo, Seok-Mo; Perinpanayagam, Hiran

    2006-10-01

    In endodontic therapy, access and instrumentation are strongly affected by root canal curvature. However, the few studies that have actually measured curvature are mostly from two-dimensional radiographs. The purpose of this study was to measure the three-dimensional (3D) canal curvature in maxillary first molars using micro-computed tomography (microCT) and mathematical modeling. Extracted maxillary first molars (46) were scanned by microCT (502 image slices/tooth, 1024 X 1024 pixels, voxel size of 19.5 x 19.5 x 39.0 microm) and their canals reconstructed by 3D modeling software. The intersection of major and minor axes in the canal space of each image slice were connected to create an imaginary central axis for each canal. The radius of curvature of the tangential circle was measured and inverted as a measure of curvature using custom-made mathematical modeling software. Root canal curvature was greatest in the apical third and least in the middle third for all canals. The greatest curvatures were in the mesiobuccal (MB) canal (0.76 +/- 0.48 mm(-1)) with abrupt curves, and the least curvatures were in the palatal (P) canal (0.38 +/- 0.34 mm(-1)) with a gradual curve. This study has measured the 3D curvature of root canals in maxillary first molars and reinforced the value of microCT with mathematical modeling.

  3. In vitro comparison of the cyclic fatigue resistance of HyFlex EDM, One G, and ProGlider nickel titanium glide path instruments in single and double curvature canals.

    Science.gov (United States)

    Yılmaz, Koray; Uslu, Gülşah; Özyürek, Taha

    2017-11-01

    It was aimed to compare the cyclic fatigue resistances of ProGlider (PG), One G (OG), and HyFlex EDM (HEDM) nickel titanium glide path files in single- and double-curved artificial canals. 40 PG (16/0.02), 40 OG (14/0.03), and 40 HEDM (10/0.05) single-file glide path files were used in the present study. Sixty files were subjected to cyclic fatigue test by using double-curved canals and 60 files by using single-curved canal ( n = 20). The number of cycles to fracture (NCF) was calculated and the length of the fractured fragment (FL) was determined by a digital micro-caliper. Twelve pieces of fractured files were examined with scanning electron microscope to determine fracture types of the files ( n = 2). The NCF and the FL data were analyzed using one-way analysis of variance and post hoc Tukey test using SPSS 21 software ( p < 0.05). In all of the groups, NCF values were significantly lower in double-curved canals when compared to single-curved canals ( p < 0.05). For both of single- and double-curved canals, NCF values of HEDM group in apical and coronal curvatures were found to be significantly higher than NCF values of PG and OG groups ( p < 0.05). In both of single- and double-curved canals, NCF value of PG group was found significantly higher than OG group ( p < 0.05). Within the limitations of this study, HEDM glide path files were found to have the highest cyclic fatigue resistance in both of single- and double-curved canals.

  4. Hysteroscopic sterilization using a virtual reality simulator: assessment of learning curve.

    Science.gov (United States)

    Janse, Juliënne A; Goedegebuure, Ruben S A; Veersema, Sebastiaan; Broekmans, Frank J M; Schreuder, Henk W R

    2013-01-01

    To assess the learning curve using a virtual reality simulator for hysteroscopic sterilization with the Essure method. Prospective multicenter study (Canadian Task Force classification II-2). University and teaching hospital in the Netherlands. Thirty novices (medical students) and five experts (gynecologists who had performed >150 Essure sterilization procedures). All participants performed nine repetitions of bilateral Essure placement on the simulator. Novices returned after 2 weeks and performed a second series of five repetitions to assess retention of skills. Structured observations on performance using the Global Rating Scale and parameters derived from the simulator provided measurements for analysis. The learning curve is represented by improvement per procedure. Two-way repeated-measures analysis of variance was used to analyze learning curves. Effect size (ES) was calculated to express the practical significance of the results (ES ≥ 0.50 indicates a large learning effect). For all parameters, significant improvements were found in novice performance within nine repetitions. Large learning effects were established for six of eight parameters (p learning curve established in this study endorses future implementation of the simulator in curricula on hysteroscopic skill acquisition for clinicians who are interested in learning this sterilization technique. Copyright © 2013 AAGL. Published by Elsevier Inc. All rights reserved.

  5. Comparative Study on Two Melting Simulation Methods: Melting Curve of Gold

    International Nuclear Information System (INIS)

    Liu Zhong-Li; Li Rui; Sun Jun-Sheng; Zhang Xiu-Lu; Cai Ling-Cang

    2016-01-01

    Melting simulation methods are of crucial importance to determining melting temperature of materials efficiently. A high-efficiency melting simulation method saves much simulation time and computational resources. To compare the efficiency of our newly developed shock melting (SM) method with that of the well-established two-phase (TP) method, we calculate the high-pressure melting curve of Au using the two methods based on the optimally selected interatomic potentials. Although we only use 640 atoms to determine the melting temperature of Au in the SM method, the resulting melting curve accords very well with the results from the TP method using much more atoms. Thus, this shows that a much smaller system size in SM method can still achieve a fully converged melting curve compared with the TP method, implying the robustness and efficiency of the SM method. (paper)

  6. Geometric analysis of root canals prepared by four rotary NiTi shaping systems.

    Science.gov (United States)

    Hashem, Ahmed Abdel Rahman; Ghoneim, Angie Galal; Lutfy, Reem Ahmed; Foda, Manar Yehia; Omar, Gihan Abdel Fatah

    2012-07-01

    A great number of nickel-titanium (NiTi) rotary systems with noncutting tips, different cross-sections, superior resistance to torsional fracture, varying tapers, and manufacturing method have been introduced to the market. The purpose of this study was to evaluate and compare the effect of 4 rotary NiTi preparation systems, Revo-S (RS; Micro-Mega, Besancon Cedex, France), Twisted file (TF; SybronEndo, Amersfoort, The Netherlands), ProFile GT Series X (GTX; Dentsply, Tulsa Dental Specialties, Tulsa, OK), and ProTaper (PT; Dentsply Maillefer, Ballaigues, Switzerland), on volumetric changes and transportation of curved root canals. Forty mesiobuccal canals of mandibular molars with an angle of curvature ranging from 25° to 40° were divided according to the instrument used in canal preparation into 4 groups of 10 samples each: group RS, group TF, group GTX, and group PT. Canals were scanned using an i-CAT CBCT scanner (Imaging Science International, Hatfield, PA) before and after preparation to evaluate the volumetric changes. Root canal transportation and centering ratio were evaluated at 1.3, 2.6, 5.2, and 7.8 mm from the apex. The significance level was set at P ≤ .05. The PT system removed a significantly higher amount of dentin than the other systems (P = .025). At the 1.3-mm level, there was no significant difference in canal transportation and centering ratio among the groups. However, at the other levels, TF maintained the original canal curvature recording significantly the least degree of canal transportation as well as the highest mean centering ratio. The TF system showed superior shaping ability in curved canals. Revo-S and GTX were better than ProTaper regarding both canal transportation and centering ability. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  7. Modificações da curvatura de canais simulados após emprego de instrumentos rotatórios Curvature modification of simulated root canals after use of rotary instruments

    Directory of Open Access Journals (Sweden)

    Suely Maria Santos LAMARÃO

    1999-01-01

    Full Text Available É a partir da instrumentação que o canal radicular adquire a forma necessária à adaptação perfeita do material obturador. Durante essa fase, é necessário que ocorra uma interação entre instrumento e canal radicular com vistas a reduzir o número de alterações decorrentes desse passo improcedente. Neste estudo, procurou-se observar a ação de dois tipos de instrumentos endodônticos mecânico-rotatórios: as limas Quantec series 2000 tipo SC, com ponta cortante, e tipo LX, com ponta embotada, na instrumentação de canais simulados com curvaturas entre 20 e 35 graus, valendo-se da técnica Quantec Graduating TapersTM. Os resultados evidenciaram que a média de alteração da curvatura dos canais do Grupo I, que foram instrumentados com limas SC, foi 2,15%; para os canais do Grupo II, instrumentados com limas LX, foi de 2,61%. Embora tenha-se verificado que os canais do Grupo I apresentaram menor percentagem de alteração da curvatura, o teste estatístico pertinente de Mann-Whitney demonstrou não existir diferença significante para ± 5% entre os dois grupos experimentais.After instrumentation, the root canal acquires the necessary shape for a perfect adaptation of filling material. During this phase cutting end and LX type an interaction between instrument and root canal is necessary in order to reduce alterations that could occur at this point. This study evaluated the action of two mechanical-rotatory endodontic instruments, Quantec files 2000 serie type SC with blunt end, during the instrumentation of simulated canals curved between 20 and 35 degrees, using quantec graduating tapers. Results showed that the mean curvature alteration of group I canals that were instrumented with SC files, was 2,15%, and for group II instrumented with LX files, was 2,61%. Furthermore group I canals showed lower percentage of curvature alteration. Mann-Whitney tests showed no significant statistical difference at 5% between experimental groups.

  8. Comparative Study of Three Rotary Instruments for root canal Preparation using Computed Tomography

    International Nuclear Information System (INIS)

    Mohamed, A.M.E.

    2015-01-01

    Cleaning and shaping the root canal is a key to success in root canal treatment. This includes the removal of organic substrate from the root canal system by chemo mechanical methods, and the shaping of the root canal system into a continuously tapered preparation. This should be done while maintaining the original path of the root canal. Although instruments for root canal preparation have been progressively developed and optimized, a complete mechanical debridement of the root canal system is rarely achievable. One of the main reasons is the geometrical dis symmetry between the root canal and preparation instruments. Rotary instruments regardless of their type and form produce a preparation with a round outline if they are used in a simple linear filing motion, which in most of the cases do not coincide with the outline of the root canal. Root canal preparation in narrow, curved canals is a challenge even for experienced endodontists. Shaping of curved canals became more effective after the introduction of nickel-titanium (Ni-Ti) endodontic instruments. Despite the advantages of Ni-Ti rotary instruments, intra canal fracture is the most common procedural accident that occurs with these instruments during clinical use. It is a common experience between clinicians that Ni-Ti rotary instruments may undergo unexpected fracture without any visible warning, such as any previous permanent defect or deformation. Pro Taper Ni-Ti instruments were introduced with a unique design of variable taper within one instrument and continuously changing helical angles. Pro Taper rotary instruments are claimed to generate lower torque values during their use because of their modified nonradial landed cross-section that increases the cutting efficiency and reduces contact areas. On the other hand, the variable taper within one instrument is believed to reduce the ‘taper lock’ effect (torsional failure) in comparison with similarly tapered instruments. Nevertheless, Pro Taper

  9. S-Shaped Canals: A Series of Cases Performed by Four Specialists around the World

    Directory of Open Access Journals (Sweden)

    Ricardo Machado

    2014-01-01

    Full Text Available Recognition of anatomical variations is a real challenge for clinicians undertaking therapy regardless of the teeth that are to be treated. The extent of the curvature is one of the most important variables that could lead to instrument fracture. In clinical conditions, two curves can be present in the same root canal trajectory. This type of geometry is denoted as the “S” shape, and it is a challenging condition. This report describes a different clinical and educational scenario where four specialists around the world present different approaches for the treatment of root canals with double curvatures or S-shaped canals. Endodontic therapy is a very nuanced and challenging science and art. The clinical and teaching experience of the authors show different approaches that can be successfully employed to treat challenging teeth having roots with multiple curves. The necessity of precise knowledge of the root canal morphology and its variation is also underlined.

  10. Influence of Operator's Experience on the Shaping Ability of Protaper Universal and Waveone Systems: A Comparative Study on Simulated Root Canals.

    Science.gov (United States)

    Troiano, Giuseppe; Dioguardi, Mario; Cocco, Armando; Giannatempo, Giovanni; Laino, Luigi; Ciavarella, Domenico; Berutti, Elio; Lo Muzio, Lorenzo

    2016-01-01

    To assess the influence of operator experience on: shaping and centering ability, mean preparation time and presence of canal aberrations of ProTaper Universal and WaveOne systems on simulated root canals. Sixty S-shaped canals in resin blocks were assigned to four groups (n=15 for each group). Group1 (Experienced operator, ProTaper), Group2 (Experienced operator, WaveOne), Group3 (Inexperienced operator, ProTaper), Group4 (Inexperienced operator, WaveOne). Photographic method was used to record pre- and post-instrumentations images. After superimposition, it has been evaluated presence of canal aberrations and differences in shaping and centering ability between groups. WaveOne system produced a lower amount of canal aberrations both in the hand of expert than inexpert operators. However, a WaveOne instrument breakage occurred in the hands of an inexperienced operator. No differences have been found in the evaluation of shaping ability with both systematics. Operator's experience doesn't influence the shaping ability of ProTaper and WaveOne systems. Experience factor could influence the centering ability in the use of both the systematics. However, WaveOne Primary reduce the mean preparation time and the presence of canal aberrations.

  11. Discharge Estimation in a Lined Canal Using Information Entropy

    Directory of Open Access Journals (Sweden)

    Yen-Chang Chen

    2014-03-01

    Full Text Available This study applies a new method and technology to measure the discharge in a lined canal in Taiwan. An Acoustic Digital Current Meter mounted on a measurement platform is used to measure the velocities over the full cross-section for establishing the measurement method. The proposed method primarily employs Chiu’s Equation which is based on entropy to establish a constant ratio the relation between the maximum and mean velocities in an irrigation canal, and compute the maximum velocity by the observed velocity profile. In consequence, the mean velocity of the lined canal can be rapidly determined by the maximum velocity and the constant ratio. The cross-sectional area of the artificial irrigation canal can be calculated for the water stage. Finally, the discharge in the lined canal can be efficiently determined by the estimated mean velocity and the cross-sectional area. Using the data of discharges and stages collected in the Wan-Dan Canal, the correlation of stage and discharge is also developed for remote real-time monitoring and estimating discharge from the pumping station. Overall, Chiu’s Equation is demonstrated to reliably and accurately measure discharge in a lined canal, and can serve as reference for future calibration for a stage-discharge rating curve.

  12. SIMULATED PERFORMANCE OF TIMESCALE METRICS FOR APERIODIC LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Findeisen, Krzysztof; Hillenbrand, Lynne [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Cody, Ann Marie, E-mail: krzys@astro.caltech.edu [Spitzer Science Center, California Institute of Technology, MC 314-6, Pasadena, CA 91125 (United States)

    2015-01-10

    Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time-domain surveys, it is increasingly essential to develop methods to quantify and analyze aperiodic variability. We develop three timescale metrics that have been little used in astronomy—Δm-Δt plots, peak-finding, and Gaussian process regression—and present simulations comparing their effectiveness across a range of aperiodic light curve shapes, characteristic timescales, observing cadences, and signal to noise ratios. We find that Gaussian process regression is easily confused by noise and by irregular sampling, even when the model being fit reflects the process underlying the light curve, but that Δm-Δt plots and peak-finding can coarsely characterize timescales across a broad region of parameter space. We make public the software we used for our simulations, both in the spirit of open research and to allow others to carry out analogous simulations for their own observing programs.

  13. SIMULATED PERFORMANCE OF TIMESCALE METRICS FOR APERIODIC LIGHT CURVES

    International Nuclear Information System (INIS)

    Findeisen, Krzysztof; Hillenbrand, Lynne; Cody, Ann Marie

    2015-01-01

    Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time-domain surveys, it is increasingly essential to develop methods to quantify and analyze aperiodic variability. We develop three timescale metrics that have been little used in astronomy—Δm-Δt plots, peak-finding, and Gaussian process regression—and present simulations comparing their effectiveness across a range of aperiodic light curve shapes, characteristic timescales, observing cadences, and signal to noise ratios. We find that Gaussian process regression is easily confused by noise and by irregular sampling, even when the model being fit reflects the process underlying the light curve, but that Δm-Δt plots and peak-finding can coarsely characterize timescales across a broad region of parameter space. We make public the software we used for our simulations, both in the spirit of open research and to allow others to carry out analogous simulations for their own observing programs

  14. Simulation of a G-tolerance curve using the pulsatile cardiovascular model

    Science.gov (United States)

    Solomon, M.; Srinivasan, R.

    1985-01-01

    A computer simulation study, performed to assess the ability of the cardiovascular model to reproduce the G tolerance curve (G level versus tolerance time) is reported. A composite strength duration curve derived from experimental data obtained in human centrifugation studies was used for comparison. The effects of abolishing automomic control and of blood volume loss on G tolerance were also simulated. The results provide additional validation of the model. The need for the presence of autonomic reflexes even at low levels of G is pointed out. The low margin of safety with a loss of blood volume indicated by the simulation results underscores the necessity for protective measures during Shuttle reentry.

  15. Evaluation of Root Canal Cleaning and Shaping Efficacy of Three Engine-driven Instruments: SafeSider, ProTaper Universal and Lightspeed LSX.

    Science.gov (United States)

    Wigler, Ronald; Koren, Tal; Tsesis, Igor

    2015-11-01

    To compare the cleaning effectiveness and shaping ability of SafeSider, ProTaper Universal and Lightspeed rotary instruments during the preparation of curved root canals in extracted human teeth. A total of 63 roots with curved root canals were divided into three groups. Canals were prepared using SafeSider, ProTaper Universal or Lightspeed LSX. Using pre- and post-instrumentation radiographs, straightening of the canal curvatures and loss of working length were determined with a computer image analysis program. The amounts of debris at the apical 5 mm were quantified on the basis of a numerical evaluation scale. The data were analyzed statistically using the two-way analysis of variance (ANOVA). There was significantly more transportation among the Lightspeed LSX group compared to the SafeSider and ProTaper Universal groups only at the 4 mm level (p engine-driven instruments with regards to debris removal. SafeSider, ProTaper Universal and Lightspeed LSX rotary instruments maintained the original canal curvature well at the apical 3 mm and were safe to use. No difference was found in cleaning efficacy and none rendered the apical part of the canal free of debris. SafeSider, ProTaper Universal and Lightspeed LSX rotary instruments are safe to use in curved root canals.

  16. Incidence of dentinal defects after preparation of severely curved root canals using the Reciproc single-file system with and without prior creation of a glide path.

    Science.gov (United States)

    Saber, S E D M; Schäfer, E

    2016-11-01

    To investigate the incidence of dentinal defects after preparation of severely curved root canals using the Reciproc single-file system with and without prior creation of a glide path. Mesial roots from extracted mandibular first molars were collected and scanned with CBCT to assess the morphology of the root canal systems. Three groups of 20 anatomically comparable specimens were generated. The control group was left unprepared, whilst the experimental groups were prepared with Reciproc R25 with and without a glide path (groups RG and R, respectively). Roots were then sectioned perpendicular to the long axis at 2, 4, 6, 8 and 10 mm from the apex, and coloured photographs of the sections at 40× were obtained. Two blinded examiners registered the presence of dentinal defects twice at 2-week interval. Data were statistically analysed using the Fisher exact and Cochran's Q tests. No defects were observed in the control group. The overall incidence of dentinal defects was 26% in group R and 24% in group RG, with no significant differences between them (P > 0.05). Dentinal defects occurred significantly more often in the middle and coronal thirds compared to the apical third of the canals (P files. © 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  17. The Simulation of an Oxidation-Reduction Titration Curve with Computer Algebra

    Science.gov (United States)

    Whiteley, Richard V., Jr.

    2015-01-01

    Although the simulation of an oxidation/reduction titration curve is an important exercise in an undergraduate course in quantitative analysis, that exercise is frequently simplified to accommodate computational limitations. With the use of readily available computer algebra systems, however, such curves for complicated systems can be generated…

  18. Light Curve Simulation Using Spacecraft CAD Models and Empirical Material Spectral BRDFS

    Science.gov (United States)

    Willison, A.; Bedard, D.

    This paper presents a Matlab-based light curve simulation software package that uses computer-aided design (CAD) models of spacecraft and the spectral bidirectional reflectance distribution function (sBRDF) of their homogenous surface materials. It represents the overall optical reflectance of objects as a sBRDF, a spectrometric quantity, obtainable during an optical ground truth experiment. The broadband bidirectional reflectance distribution function (BRDF), the basis of a broadband light curve, is produced by integrating the sBRDF over the optical wavelength range. Colour-filtered BRDFs, the basis of colour-filtered light curves, are produced by first multiplying the sBRDF by colour filters, and integrating the products. The software package's validity is established through comparison of simulated reflectance spectra and broadband light curves with those measured of the CanX-1 Engineering Model (EM) nanosatellite, collected during an optical ground truth experiment. It is currently being extended to simulate light curves of spacecraft in Earth orbit, using spacecraft Two-Line-Element (TLE) sets, yaw/pitch/roll angles, and observer coordinates. Measured light curves of the NEOSSat spacecraft will be used to validate simulated quantities. The sBRDF was chosen to represent material reflectance as it is spectrometric and a function of illumination and observation geometry. Homogeneous material sBRDFs were obtained using a goniospectrometer for a range of illumination and observation geometries, collected in a controlled environment. The materials analyzed include aluminum alloy, two types of triple-junction photovoltaic (TJPV) cell, white paint, and multi-layer insulation (MLI). Interpolation and extrapolation methods were used to determine the sBRDF for all possible illumination and observation geometries not measured in the laboratory, resulting in empirical look-up tables. These look-up tables are referenced when calculating the overall sBRDF of objects, where

  19. Comparison of radiographic density and compaction index of root canal obturation using nickel titanium or stainless-steel spreaders

    Directory of Open Access Journals (Sweden)

    M. Adel

    2016-08-01

    Full Text Available Background: Both nickel titanium and stainless-steel spreaders are available. The obvious advantage of nickel titanium spreader over stainless steel spreaders is greater penetration in curved canals. Objective: To compare the radiographic density and compaction index of root canal obturation using nickel-titanium or stainless-steel spreaders in curved canals. Methods: In this experimental study the primary weight of 30 acrylic blocks with 45o degrees of apical curvature were measured by a scale (W1. After canals were prepared by step back master apical up to file #30 all blocks were weighed again (W2 and randomly divided in two groups of 15each. All canals were obturated by Cold lateral compaction technique (with nickel-titanium in one group and stainless-steel finger spreaders in another group. After all blocks were reweighed (W3, compaction index (W3-W2/W1-W2 was calculated. One radiograph was taken for each sample. Apical density of the apical third of each canal was measured by digital transmission densitometer. Data were analyzed statistically using T-test. Findings: Mean compaction index for nickel-titanium group was 7.67±2.38 and for stainless-steel group was 9.14±4.06. There was no significant difference between two groups. Mean radiographic density of obturation was 2.05±0.14 in nickel-titanium group and was 2.07±0.21 in stainless-steel group. There was no significant difference between two groups. Conclusion: It is concluded that nickel-titanium spreaders are not superior than stainless-steel spreaders in obturating curved canal.

  20. CT evaluation of canal preparation using rotary and hand NI-TI instruments: An in vitro study.

    Science.gov (United States)

    Nagaraja, Shruthi; Sreenivasa Murthy, B V

    2010-01-01

    Controlled, uniformly tapered radicular preparation is a great challenge in endodontics. Improper preparation can lead to procedural errors like transportation of foramen, uneven dentine thickness, stripping of root canal, formation of ledge, zip, and elbow in curved canals. These procedural errors and their sequel can adversely affect the prognosis of treatment. The present in vitro study aims to evaluate canal preparation based on the following factors: canal transportation, remaining dentine thickness and comparing centering ability between hand Ni-Ti K files and ProTaper rotary Ni-Ti instruments using computed tomography (CT). For evaluation, 30 mesiobuccal roots of maxillary molars were selected. Of these, 15 roots were distributed into two groups where Group 1 included hand instrumentation with Ni-Ti K-files; and Group 2 comprised ProTaper NiTi rotary system. Pre instrumentation and post instrumentation three-dimensional CT images were obtained from root cross-sections that were 1 mm thick from apex to the canal orifice; scanned images were then superimposed and compared. It was observed that the manual technique using hand Ni-Ti K-file produced lesser canal transportation and maintained greater dentine thickness than the rotary ProTaper technique at middle and coronal third and this difference was statistically significant. No significant difference was seen with regard to canal transportation and remaining root dentine at apical levels. With regard to centering ratio, no significant difference was seen between both the groups at all levels. ProTaper should be used judiciously, especially in curved canals, as it causes higher canal transportation and thinning of root dentine at middle and coronal levels. None of the groups showed optimal centering ability.

  1. An in vitro comparison of root canal transportation by reciproc file with and without glide path.

    Science.gov (United States)

    Nazarimoghadam, Kiumars; Daryaeian, Mohammad; Ramazani, Nahid

    2014-09-01

    The aim of ideal canal preparation is to prevent iatrogenic aberrations such as transportation. The aim of this study was to evaluate the root canal transportation by Reciproc file with and without glide path. Thirty acrylic-resin blocks with a curvature of 60° and size#10 (2% taper) were assigned into two groups (n= 15). In group 1, the glide path was performed using stainless steel k-files size#10 and 15 at working length In group 2, canals were prepared with Reciproc file system at working length. By using digital imaging software (AutoCAD 2008), the pre-instrumentation and post-instrumentation digital images were superimposed over, taking the landmarks as reference points. Then the radius of the internal and external curve of the specimens was calculated at three α, β and γ points (1mm to apex as α, 3mm to apex as β, and 5mm to apex as γ). The data were statically analyzed using the independent T-test and Mann-Whitney U test by SPSS version 16. Glide path was found significant for only external curve in the apical third of the canal; that is, 5mm to apex (P=0.005). But in the other third, canal modification was not significant (P> 0.008). Canal transportation in the apical third of the canal seems to be significantly reduced when glide path is performed using reciprocating files.

  2. Adductor Canal Block versus Femoral Nerve Block and Quadriceps Strength

    DEFF Research Database (Denmark)

    Jæger, Pia Therese; Nielsen, Zbigniew Jerzy Koscielniak; Henningsen, Lene Marianne

    2013-01-01

    : The authors hypothesized that the adductor canal block (ACB), a predominant sensory blockade, reduces quadriceps strength compared with placebo (primary endpoint, area under the curve, 0.5-6 h), but less than the femoral nerve block (FNB; secondary endpoint). Other secondary endpoints were...

  3. Comparison of canal transportation and centering ability of hand Protaper files and rotary Protaper files by using micro computed tomography

    OpenAIRE

    Amit Gandhi; Taru Gandhi

    2011-01-01

    Introduction and objective: The aim of the present study was to compare root canal preparation with rotary ProTaper files and hand ProTaper files to find a better instrumentation technique for maintaining root canal geometry with the aid of computed tomography. Material and methods: Twenty curved root canals with at least 10 degree of curvature were divided into 2 groups of 10 teeth each. In group I the canals were prepared with hand ProTaper files and in group II the canals were prepared wit...

  4. Micro-CT evaluation of several glide path techniques and ProTaper Next shaping outcomes in maxillary first molar curved canals.

    Science.gov (United States)

    Alovisi, M; Cemenasco, A; Mancini, L; Paolino, D; Scotti, N; Bianchi, C C; Pasqualini, D

    2017-04-01

    To evaluate the ability of ProGlider instruments, PathFiles and K-files to maintain canal anatomy during glide path preparation using X-ray computed micro-tomography (micro-CT). Forty-five extracted maxillary first permanent molars were selected. Mesio-buccal canals were randomly assigned (n = 15) to manual K-file, PathFile or ProGlider groups for glide path preparation. Irrigation was achieved with 5% NaOCl and 10% EDTA. After glide path preparation, each canal was shaped with ProTaper Next X1 and X2 to working length. Specimens were scanned (isotropic voxel size 9.1 μm) for matching volumes and surface areas and post-treatment analyses. Canal volume, surface area, centroid shift, canal geometry variation through ratio of diameter ratios and ratio of cross-sectional areas were assessed in the apical and coronal levels and at the point of maximum canal curvature. One-way factorial anovas were used to evaluate the significance of instrument in the various canal regions. Post-glide path analysis revealed that instrument factor was significant at the apical level for both the ratio of diameter ratios and the ratio of cross-sectional areas (P flare the root canal compared with K-file and PathFile. PathFile and ProGlider demonstrated a significantly lower centroid shift compared with K-file at the apical level (P = 0.023). Post-shaping analysis demonstrated a more centred preparation of ProGlider, compared with PathFile and K-files, with no significant differences for other parameters. Use of ProGlider instruments led to less canal transportation than PathFiles and K-files. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  5. CT evaluation of canal preparation using rotary and hand NI-TI instruments: An in vitro study

    Science.gov (United States)

    Nagaraja, Shruthi; Sreenivasa Murthy, B V

    2010-01-01

    Background: Controlled, uniformly tapered radicular preparation is a great challenge in endodontics. Improper preparation can lead to procedural errors like transportation of foramen, uneven dentine thickness, stripping of root canal, formation of ledge, zip, and elbow in curved canals. These procedural errors and their sequel can adversely affect the prognosis of treatment. Aim/Objectives: The present in vitro study aims to evaluate canal preparation based on the following factors: canal transportation, remaining dentine thickness and comparing centering ability between hand Ni-Ti K files and ProTaper rotary Ni-Ti instruments using computed tomography (CT). Materials and Methods: For evaluation, 30 mesiobuccal roots of maxillary molars were selected. Of these, 15 roots were distributed into two groups where Group 1 included hand instrumentation with Ni-Ti K-files; and Group 2 comprised ProTaper NiTi rotary system. Pre instrumentation and post instrumentation three-dimensional CT images were obtained from root cross-sections that were 1 mm thick from apex to the canal orifice; scanned images were then superimposed and compared. Result: It was observed that the manual technique using hand Ni-Ti K-file produced lesser canal transportation and maintained greater dentine thickness than the rotary ProTaper technique at middle and coronal third and this difference was statistically significant. No significant difference was seen with regard to canal transportation and remaining root dentine at apical levels. With regard to centering ratio, no significant difference was seen between both the groups at all levels. Conclusion: ProTaper should be used judiciously, especially in curved canals, as it causes higher canal transportation and thinning of root dentine at middle and coronal levels. None of the groups showed optimal centering ability. PMID:20582214

  6. Multi-Band Light Curves from Two-Dimensional Simulations of Gamma-Ray Burst Afterglows

    Science.gov (United States)

    MacFadyen, Andrew

    2010-01-01

    The dynamics of gamma-ray burst outflows is inherently multi-dimensional. 1.) We present high resolution two-dimensional relativistic hydrodynamics simulations of GRBs in the afterglow phase using adaptive mesh refinement (AMR). Using standard synchrotron radiation models, we compute multi-band light curves, from the radio to X-ray, directly from the 2D hydrodynamics simulation data. We will present on-axis light curves for both constant density and wind media. We will also present off-axis light curves relevant for searches for orphan afterglows. We find that jet breaks are smoothed due to both off-axis viewing and wind media effects. 2.) Non-thermal radiation mechanisms in GRB afterglows require substantial magnetic field strengths. In turbulence driven by shear instabilities in relativistic magnetized gas, we demonstrate that magnetic field is naturally amplified to half a percent of the total energy (epsilon B = 0.005). We will show high resolution three dimensional relativistic MHD simulations of this process as well as particle in cell (PIC) simulations of mildly relativistic collisionless shocks.

  7. On a framework for generating PoD curves assisted by numerical simulations

    Energy Technology Data Exchange (ETDEWEB)

    Subair, S. Mohamed, E-mail: prajagopal@iitm.ac.in; Agrawal, Shweta, E-mail: prajagopal@iitm.ac.in; Balasubramaniam, Krishnan, E-mail: prajagopal@iitm.ac.in; Rajagopal, Prabhu, E-mail: prajagopal@iitm.ac.in [Indian Institute of Technology Madras, Department of Mechanical Engineering, Chennai, T.N. (India); Kumar, Anish; Rao, Purnachandra B.; Tamanna, Jayakumar [Indira Gandhi Centre for Atomic Research, Metallurgy and Materials Group, Kalpakkam, T.N. (India)

    2015-03-31

    The Probability of Detection (PoD) curve method has emerged as an important tool for the assessment of the performance of NDE techniques, a topic of particular interest to the nuclear industry where inspection qualification is very important. The conventional experimental means of generating PoD curves though, can be expensive, requiring large data sets (covering defects and test conditions), and equipment and operator time. Several methods of achieving faster estimates for PoD curves using physics-based modelling have been developed to address this problem. Numerical modelling techniques are also attractive, especially given the ever-increasing computational power available to scientists today. Here we develop procedures for obtaining PoD curves, assisted by numerical simulation and based on Bayesian statistics. Numerical simulations are performed using Finite Element analysis for factors that are assumed to be independent, random and normally distributed. PoD curves so generated are compared with experiments on austenitic stainless steel (SS) plates with artificially created notches. We examine issues affecting the PoD curve generation process including codes, standards, distribution of defect parameters and the choice of the noise threshold. We also study the assumption of normal distribution for signal response parameters and consider strategies for dealing with data that may be more complex or sparse to justify this. These topics are addressed and illustrated through the example case of generation of PoD curves for pulse-echo ultrasonic inspection of vertical surface-breaking cracks in SS plates.

  8. Centering Ability of ProTaper Next and WaveOne Classic in J-Shape Simulated Root Canals.

    Science.gov (United States)

    Troiano, Giuseppe; Dioguardi, Mario; Cocco, Armando; Giuliani, Michele; Fabiani, Cristiano; D'Alessandro, Alfonso; Ciavarella, Domenico; Lo Muzio, Lorenzo

    Introduction . The aim of this study was to evaluate and compare the shaping and centering ability of ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland) and WaveOne Classic systems (Dentsply Maillefer) in simulated root canals. Methods . Forty J-shaped canals in resin blocks were assigned to two groups ( n = 20 for each group). Photographic method was used to record pre- and postinstrumentation images. After superimposition, centering and shaping ability were recorded at 9 different levels from the apex using the software Autocad 2013 (Autodesk Inc., San Rafael, USA). Results . Shaping procedures with ProTaper Next resulted in a lower amount of resin removed at each reference point level. In addition, the pattern of centering ability improved after the use of ProTaper Next in 8 of 9 measurement points. Conclusions . Within the limitations of this study, shaping procedures with ProTaper Next instruments demonstrated a lower amount of resin removed and a better centering ability than WaveOne Classic system.

  9. Performance curves of room air conditioners for building energy simulation tools

    International Nuclear Information System (INIS)

    Meissner, José W.; Abadie, Marc O.; Moura, Luís M.; Mendonça, Kátia C.; Mendes, Nathan

    2014-01-01

    Highlights: • Experimental characteristic curves for two room air conditioners are presented. • These results can be implemented in building simulation codes. • The energy consumption under different conditions can numerically determine. • The labeled higher energy efficiency product not always provides the best result. - Abstract: In order to improve the modeling of air conditioners in building simulation tools, the characteristic curves for total cooling capacity, sensible cooling capacity and energy efficiency ratio of two room units were determined. They were obtained by means of standard capacity tests on climatic chambers in a set of environmental conditions described by external dry- and internal wet bulb temperatures. Afterward, the performance of these two units and that of four other units, with and without taking into to account the thermodynamic variations of the surrounding environments on it, were compared using a whole building simulation program for simulating a conditioned space. The comparative analysis showed that the air conditioner with the higher energy efficiency rating not always provides the lowest power consumption in real conditions of use

  10. Characterization of mandibular molar root and canal morphology using cone beam computed tomography and its variability in Belgian and Chilean population samples

    International Nuclear Information System (INIS)

    Torres, Andres; Jacobs, Reinhilde; Lambrechts, Paul; Brizuela, Claudia; Cabrera, Carolina; Concha, Guillermo; Pedemonte, Maria Eugenia

    2015-01-01

    This study used cone-beam computed tomography (CBCT) to characterize mandibular molar root and canal morphology and its variability in Belgian and Chilean population samples. We analyzed the CBCT images of 515 mandibular molars (257 from Belgium and 258 from Chile). Molars meeting the inclusion criteria were analyzed to determine (1) the number of roots; (2) the root canal configuration; (3) the presence of a curved canal in the cross-sectional image of the distal root in the mandibular first molar and (4) the presence of a C-shaped canal in the second mandibular molar. A descriptive analysis was performed. The association between national origin and the presence of a curved or C-shaped canal was evaluated using the chi-squared test. The most common configurations in the mesial root of both molars were type V and type III. In the distal root, type I canal configuration was the most common. Curvature in the cross-sectional image was found in 25% of the distal canals of the mandibular first molars in the Belgian population, compared to 11% in the Chilean population. The prevalence of C-shaped canals was 10% or less in both populations. In cases of unclear or complex root and canal morphology in the mandibular molars, CBCT imaging might assist endodontic specialists in making an accurate diagnosis and in treatment planning

  11. Two dimensional hybrid simulation of a curved bow shock

    International Nuclear Information System (INIS)

    Thomas, V.A.; Winske, D.

    1990-01-01

    Results are presented from two dimensional hybrid simulations of curved collisionless supercritical shocks, retaining both quasi-perpendicular and quasi-parallel sections of the shock in order to study the character and origin of the foreshock ion population. The simulations demonstrate that the foreshock ion population is dominated by ions impinging upon the quasi-parallel side of the shock, while nonlocal transport from the quasi-perpendicular side of the shock into the foreshock region is minimal. Further, it is shown that the ions gain energy by drifting significantly in the direction of the convection electric field through multiple shock encounters

  12. Identification of dental root canals and their medial line from micro-CT and cone-beam CT records

    Directory of Open Access Journals (Sweden)

    Benyó Balázs

    2012-10-01

    Full Text Available Abstract Background Shape of the dental root canal is highly patient specific. Automated identification methods of the medial line of dental root canals and the reproduction of their 3D shape can be beneficial for planning endodontic interventions as severely curved root canals or multi-rooted teeth may pose treatment challenges. Accurate shape information of the root canals may also be used by manufacturers of endodontic instruments in order to make more efficient clinical tools. Method Novel image processing procedures dedicated to the automated detection of the medial axis of the root canal from dental micro-CT and cone-beam CT records are developed. For micro-CT, the 3D model of the root canal is built up from several hundred parallel cross sections, using image enhancement, histogram based fuzzy c-means clustering, center point detection in the segmented slice, three dimensional inner surface reconstruction, and potential field driven curve skeleton extraction in three dimensions. Cone-beam CT records are processed with image enhancement filters and fuzzy chain based regional segmentation, followed by the reconstruction of the root canal surface and detecting its skeleton via a mesh contraction algorithm. Results The proposed medial line identification and root canal detection algorithms are validated on clinical data sets. 25 micro-CT and 36 cone-beam-CT records are used in the validation procedure. The overall success rate of the automatic dental root canal identification was about 92% in both procedures. The algorithms proved to be accurate enough for endodontic therapy planning. Conclusions Accurate medial line identification and shape detection algorithms of dental root canal have been developed. Different procedures are defined for micro-CT and cone-beam CT records. The automated execution of the subsequent processing steps allows easy application of the algorithms in the dental care. The output data of the image processing procedures

  13. Stability of guest molecules in urea canal complexes by canal polymerization

    International Nuclear Information System (INIS)

    Yoshii, Fumio; Makuuchi, Keizo

    1995-01-01

    It was found that various organic materials are attracted into urea canal by hexanediol diacrylate (HDDA) and long chain compounds. This means that materials which does not form complex by itself are induced in canal by HDDA and long chain compounds. To include with stability perfumes, insecticides, attractants and repellents in urea canal, leaf alcohol was used as a model compound for guest molecules in the canal. The leaf alcohol from the canal released gradually over many days and the release was inhibited for 15 days by long chain compounds and for 30 days by polymerized HDDA after irradiation. After releasing, the leaf alcohol in the canal remained 25 % stable for long chain compounds and 40 % for polymerized HDDA. The dose required for stabilization of leaf alcohol in the urea canal by canal polymerization of HDDA was 30 kGy. (author)

  14. Simulation-optimization model of reservoir operation based on target storage curves

    Directory of Open Access Journals (Sweden)

    Hong-bin Fang

    2014-10-01

    Full Text Available This paper proposes a new storage allocation rule based on target storage curves. Joint operating rules are also proposed to solve the operation problems of a multi-reservoir system with joint demands and water transfer-supply projects. The joint operating rules include a water diversion rule to determine the amount of diverted water in a period, a hedging rule based on an aggregated reservoir to determine the total release from the system, and a storage allocation rule to specify the release from each reservoir. A simulation-optimization model was established to optimize the key points of the water diversion curves, the hedging rule curves, and the target storage curves using the improved particle swarm optimization (IPSO algorithm. The multi-reservoir water supply system located in Liaoning Province, China, including a water transfer-supply project, was employed as a case study to verify the effectiveness of the proposed join operating rules and target storage curves. The results indicate that the proposed operating rules are suitable for the complex system. The storage allocation rule based on target storage curves shows an improved performance with regard to system storage distribution.

  15. The melting curve of MgSiO3 perovskite from molecular dynamics simulation

    International Nuclear Information System (INIS)

    Liu Zijiang; Zhang Cairong; Sun Xiaowei; Song Ting; Chu Yandong; Hu Jianbo

    2011-01-01

    The high-pressure melting curve of MgSiO 3 perovskite is simulated by using the constant temperature and pressure molecular dynamics method combined with effective pair potentials. The simulated structural properties of MgSiO 3 perovskite at ambient conditions reproduce the experiments and agree well with other theoretical works. The calculated equation of state is very successful in reproducing accurately the recent experimental data over wide pressure ranges. The predicted high-pressure melting curve is in good agreement with the recent experimental and the latest theoretical ones, and the melting curve up to the core-mantle boundary pressure, being very steep at lower pressures, rapidly flattens on increasing pressure. The present results also suggest the validity of the experimental data of Zerr and Boehler (1993 Science 262 553) and Shen and Lazor (1995 J. Geophys. Res. 100 17699).

  16. Root canal irrigants

    OpenAIRE

    Kandaswamy, Deivanayagam; Venkateshbabu, Nagendrababu

    2010-01-01

    Successful root canal therapy relies on the combination of proper instrumentation, irrigation, and obturation of the root canal. Of these three essential steps of root canal therapy, irrigation of the root canal is the most important determinant in the healing of the periapical tissues. The primary endodontic treatment goal must thus be to optimize root canal disinfection and to prevent reinfection. In this review of the literature, various irrigants and the interactions between irrigants are...

  17. Curve Boxplot: Generalization of Boxplot for Ensembles of Curves.

    Science.gov (United States)

    Mirzargar, Mahsa; Whitaker, Ross T; Kirby, Robert M

    2014-12-01

    In simulation science, computational scientists often study the behavior of their simulations by repeated solutions with variations in parameters and/or boundary values or initial conditions. Through such simulation ensembles, one can try to understand or quantify the variability or uncertainty in a solution as a function of the various inputs or model assumptions. In response to a growing interest in simulation ensembles, the visualization community has developed a suite of methods for allowing users to observe and understand the properties of these ensembles in an efficient and effective manner. An important aspect of visualizing simulations is the analysis of derived features, often represented as points, surfaces, or curves. In this paper, we present a novel, nonparametric method for summarizing ensembles of 2D and 3D curves. We propose an extension of a method from descriptive statistics, data depth, to curves. We also demonstrate a set of rendering and visualization strategies for showing rank statistics of an ensemble of curves, which is a generalization of traditional whisker plots or boxplots to multidimensional curves. Results are presented for applications in neuroimaging, hurricane forecasting and fluid dynamics.

  18. Development of theoretical oxygen saturation calibration curve based on optical density ratio and optical simulation approach

    Science.gov (United States)

    Jumadi, Nur Anida; Beng, Gan Kok; Ali, Mohd Alauddin Mohd; Zahedi, Edmond; Morsin, Marlia

    2017-09-01

    The implementation of surface-based Monte Carlo simulation technique for oxygen saturation (SaO2) calibration curve estimation is demonstrated in this paper. Generally, the calibration curve is estimated either from the empirical study using animals as the subject of experiment or is derived from mathematical equations. However, the determination of calibration curve using animal is time consuming and requires expertise to conduct the experiment. Alternatively, an optical simulation technique has been used widely in the biomedical optics field due to its capability to exhibit the real tissue behavior. The mathematical relationship between optical density (OD) and optical density ratios (ODR) associated with SaO2 during systole and diastole is used as the basis of obtaining the theoretical calibration curve. The optical properties correspond to systolic and diastolic behaviors were applied to the tissue model to mimic the optical properties of the tissues. Based on the absorbed ray flux at detectors, the OD and ODR were successfully calculated. The simulation results of optical density ratio occurred at every 20 % interval of SaO2 is presented with maximum error of 2.17 % when comparing it with previous numerical simulation technique (MC model). The findings reveal the potential of the proposed method to be used for extended calibration curve study using other wavelength pair.

  19. Endodontic shaping performance using nickel-titanium hand and motor ProTaper systems by novice dental students.

    Science.gov (United States)

    Tu, Ming-Gene; Chen, San-Yue; Huang, Heng-Li; Tsai, Chi-Cheng

    2008-05-01

    Preparing a continuous tapering conical shape and maintaining the original shape of a canal are obligatory in root canal preparation. The purpose of this study was to compare the shaping performance in simulated curved canal resin blocks of the same novice dental students using hand-prepared and engine-driven nickel-titanium (NiTi) rotary ProTaper instruments in an endodontic laboratory class. Twenty-three fourth-year dental students attending China Medical University Dental School prepared 46 simulated curved canals in resin blocks with two types of NiTi rotary systems: hand and motor ProTaper files. Composite images were prepared for estimation. Material removed, canal width and canal deviation were measured at five levels in the apical 4 mm of the simulated curved canals using AutoCAD 2004 software. Data were analyzed using Wilcoxon's rank-sum test. The hand ProTaper group cut significantly wider than the motor rotary ProTaper group in the outer wall, except for the apical 0 mm point. The total canal width was cut significantly larger in the hand group than in the motor group. There was no significant difference between the two groups in centering canal shape, except at the 3 mm level. These findings show that the novice students prepared the simulated curved canal that deviated more outwardly from apical 1 mm to 4 mm using the hand ProTaper. The ability to maintain the original curvature was better in the motor rotary ProTaper group than in the hand ProTaper group. Undergraduate students, if following the preparation sequence carefully, could successfully perform canal shaping by motor ProTaper files and achieve better root canal geometry than by using hand ProTaper files within the same teaching and practicing sessions.

  20. Training, Simulation, the Learning Curve, and How to Reduce Complications in Urology.

    Science.gov (United States)

    Brunckhorst, Oliver; Volpe, Alessandro; van der Poel, Henk; Mottrie, Alexander; Ahmed, Kamran

    2016-04-01

    Urology is at the forefront of minimally invasive surgery to a great extent. These procedures produce additional learning challenges and possess a steep initial learning curve. Training and assessment methods in surgical specialties such as urology are known to lack clear structure and often rely on differing operative flow experienced by individuals and institutions. This article aims to assess current urology training modalities, to identify the role of simulation within urology, to define and identify the learning curves for various urologic procedures, and to discuss ways to decrease complications in the context of training. A narrative review of the literature was conducted through December 2015 using the PubMed/Medline, Embase, and Cochrane Library databases. Evidence of the validity of training methods in urology includes observation of a procedure, mentorship and fellowship, e-learning, and simulation-based training. Learning curves for various urologic procedures have been recommended based on the available literature. The importance of structured training pathways is highlighted, with integration of modular training to ensure patient safety. Valid training pathways are available in urology. The aim in urology training should be to combine all of the available evidence to produce procedure-specific curricula that utilise the vast array of training methods available to ensure that we continue to improve patient outcomes and reduce complications. The current evidence for different training methods available in urology, including simulation-based training, was reviewed, and the learning curves for various urologic procedures were critically analysed. Based on the evidence, future pathways for urology curricula have been suggested to ensure that patient safety is improved. Copyright © 2016 European Association of Urology. Published by Elsevier B.V. All rights reserved.

  1. Computed micro-tomographic evaluation of glide path with nickel-titanium rotary PathFile in maxillary first molars curved canals.

    Science.gov (United States)

    Pasqualini, Damiano; Bianchi, Caterina Chiara; Paolino, Davide Salvatore; Mancini, Lucia; Cemenasco, Andrea; Cantatore, Giuseppe; Castellucci, Arnaldo; Berutti, Elio

    2012-03-01

    X-ray computed micro-tomography scanning allows high-resolution 3-dimensional imaging of small objects. In this study, micro-CT scanning was used to compare the ability of manual and mechanical glide path to maintain the original root canal anatomy. Eight extracted upper first permanent molars were scanned at the TOMOLAB station at ELETTRA Synchrotron Light Laboratory in Trieste, Italy, with a microfocus cone-beam geometry system. A total of 2,400 projections on 360° have been acquired at 100 kV and 80 μA, with a focal spot size of 8 μm. Buccal root canals of each specimen (n = 16) were randomly assigned to PathFile (P) or stainless-steel K-file (K) to perform glide path at the full working length. Specimens were then microscanned at the apical level (A) and at the point of the maximum curvature level (C) for post-treatment analyses. Curvatures of root canals were classified as moderate (≤35°) or severe (≥40°). The ratio of diameter ratios (RDRs) and the ratio of cross-sectional areas (RAs) were assessed. For each level of analysis (A and C), 2 balanced 2-way factorial analyses of variance (P < .05) were performed to evaluate the significance of the instrument factor and of canal curvature factor as well as the interactions of the factors both with RDRs and RAs. Specimens in the K group had a mean curvature of 35.4° ± 11.5°; those in the P group had a curvature of 38° ± 9.9°. The instrument factor (P and K) was extremely significant (P < .001) for both the RDR and RA parameters, regardless of the point of analysis. Micro-CT scanning confirmed that NiTi rotary PathFile instruments preserve the original canal anatomy and cause less canal aberrations. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  2. Hand and nickel-titanium root canal instrumentation performed by dental students: a micro-computed tomographic study.

    Science.gov (United States)

    Peru, M; Peru, C; Mannocci, F; Sherriff, M; Buchanan, L S; Pitt Ford, T R

    2006-02-01

    The aim of this study was to evaluate root canals instrumented by dental students using the modified double-flared technique, nickel-titanium (NiTi) rotary System GT files and NiTi rotary ProTaper files by micro-computed tomography (MCT). A total of 36 root canals from 18 mesial roots of mandibular molar teeth were prepared; 12 canals were prepared with the modified double-flared technique, using K-flexofiles and Gates-Glidden burs; 12 canals were prepared using System GT and 12 using ProTaper rotary files. Each root was scanned using MCT preoperatively and postoperatively. At the coronal and mid-root sections, System GT and ProTaper files produced significantly less enlarged canal cross-sectional area, volume and perimeter than the modified double-flared technique (P ProTaper (P ProTaper and System GT were able to prepare root canals with little or no procedural error compared with the modified double-flared technique. Under the conditions of this study, inexperienced dental students were able to prepare curved root canals with rotary files with greater preservation of tooth structure, low risk of procedural errors and much quicker than with hand instruments.

  3. Evaluation of interference of calcium hydroxide-based intracanal medication in filling root canal systems.

    Science.gov (United States)

    Vilela, Deyla Duarte; Neto, Manoel Matos; Villela, Alexandre Mascarenhas; Pithon, Matheus Melo

    2011-09-01

    To evaluate the interference of the intracanal medication Calen® (SSWhite, Sao Paulo, Brazil) on the filling of simulated lateral canals. Twenty human anterior teeth were used. Before the endodontic filling procedures the access of cavity was made, and after this root canals were made in all the teeth to simulate the presence of lateral canals. After preparation, the teeth were randomly divided into two groups (n=10). In group I, the root canal system was filled directly after chemicalmechanical preparation; in group II, endodontic treatment was performed in multiple sessions, and after preparation the calcium hydroxide-based intracanal medication Calen® was inserted. After the period of 7 days, the root canals were vigorously irrigated and then they were filled. Next, the teeth were radiographed to verify the quality of the filling. The results demonstrated that the teeth treated in a single session, without calcium hydroxide medication, presented 47 canals out of 60 with radiographic evidence of filling, whereas the teeth in which intracanal medication was used, only 07 presented a radiographic image compatible with filling (p < 0.05). The use of the calcium hydroxide-based medication Calen made it difficult to obtain a hermetic filling of the root canal system. The clinical significance of this work basing on the fact that once the dentist knowing that property obliteration of calcium hydroxide can be taken care when they are used in the presence of lateral canals.

  4. Instrument separation analysis of multi-used ProTaper Universal rotary system during root canal therapy.

    Science.gov (United States)

    Wu, Jintao; Lei, Gang; Yan, Ming; Yu, Yan; Yu, Jinhua; Zhang, Guangdong

    2011-06-01

    The purpose of this study was to identify the influential factors responsible for clinical instrument separation of reused ProTaper Universal rotary instruments (Dentsply Maillefer, Ballaigues, Switzerland). Six thousand one hundred fifty-four root canals in 2,654 teeth were prepared using ProTaper Universal files in endodontic clinics. Separation incidence was determined based on the number of treated teeth or canals. Data were collected including the size of fractured instrument, the length and location of a broken segment within the root canal, and the curvature of canal. The chi-square test and independent samples t test were used to determine the statistical significance. The overall instrument separation incidences were 2.6% according to the number of teeth and 1.1% according to the canal number, respectively. Separation incidences according to the number of teeth or canals were significantly higher (P molars than those in premolars or anterior teeth. Because of its largest diameter, F3 file presented the highest separation incidence according to the number of teeth (1.0%) or canals (0.4%); 47.5% instrument separation of mandibular molars and 61.5% instrument separation of maxillary molars happened in the mesiobuccal canals. Moreover, 91.4% fragments were located in the apical third of root canals, and 54.2% instrument separation occurred in severely curved canals. There was a significant difference (P < .05) in the mean fracture length between shaping (2.42 ± 0.73 mm) and finishing files (3.32 ± 0.73 mm). Separation incidence according to the canal number is more reliable than that according to the number of teeth because of the variable canal number in different teeth. The tooth type, rotary file size, canal location, and anatomy were correlated with the instrument separation of reused ProTaper Universal files. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  5. Comparison of canal transportation and centering ability of rotary protaper, one shape system and wave one system using cone beam computed tomography: An in vitro study

    Science.gov (United States)

    Tambe, Varsha Harshal; Nagmode, Pradnya Sunil; Abraham, Sathish; Patait, Mahendra; Lahoti, Pratik Vinod; Jaju, Neha

    2014-01-01

    Aim: The aim of the present study was to compare the canal transportation and centering ability of Rotary ProTaper, One Shape and Wave One systems using cone beam computed tomography (CBCT) in curved root canals to find better instrumentation technique for maintaining root canal geometry. Materials and Methods: Total 30 freshly extracted premolars having curved root canals with at least 10 degrees of curvature were divided into three groups of 10 teeth each. All teeth were scanned by CBCT to determine the root canal shape before instrumentation. In Group 1, the canals were prepared with Rotary ProTaper files, in Group 2 the canals were prepared with One Shape files and in Group 3 canals were prepared with Wave One files. After preparation, post-instrumentation scan was performed. Pre-instrumentation and post-instrumentation images were obtained at three levels, 3 mm apical, 3 mm coronal and 8 mm apical above the apical foramen were compared using CBCT software. Amount of transportation and centering ability were assessed. The three groups were statistically compared with analysis of variance and Tukey honestly significant. Results: All instruments maintained the original canal curvature with significant differences between the different files. Data suggested that Wave One files presented the best outcomes for both the variables evaluated. Wave One files caused lesser transportation and remained better centered in the canal than One Shape and Rotary ProTaper files. Conclusion: The canal preparation with Wave One files showed lesser transportation and better centering ability than One Shape and ProTaper. PMID:25506145

  6. Positional glow curve simulation for thermoluminescent detector (TLD) system design

    International Nuclear Information System (INIS)

    Branch, C.J.; Kearfott, K.J.

    1999-01-01

    Multi- and thin element dosimeters, variable heating rate schemes, and glow-curve analysis have been employed to improve environmental and personnel dosimetry using thermoluminescent detectors (TLDs). Detailed analysis of the effects of errors and optimization of techniques would be highly desirable. However, an understanding of the relationship between TL light production, light attenuation, and precise heating schemes is made difficult because of experimental challenges involved in measuring positional TL light production and temperature variations as a function of time. This work reports the development of a general-purpose computer code, thermoluminescent detector simulator, TLD-SIM, to simulate the heating of any TLD type using a variety of conventional and experimental heating methods including pulsed focused or unfocused lasers with Gaussian or uniform cross sections, planchet, hot gas, hot finger, optical, infrared, or electrical heating. TLD-SIM has been used to study the impact on the TL light production of varying the input parameters which include: detector composition, heat capacity, heat conductivity, physical size, and density; trapped electron density, the frequency factor of oscillation of electrons in the traps, and trap-conduction band potential energy difference; heating scheme source terms and heat transfer boundary conditions; and TL light scatter and attenuation coefficients. Temperature profiles and glow curves as a function of position time, as well as the corresponding temporally and/or spatially integrated glow values, may be plotted while varying any of the input parameters. Examples illustrating TLD system functions, including glow curve variability, will be presented. The flexible capabilities of TLD-SIM promises to enable improved TLD system design

  7. Irrigant flow in the root canal: experimental validation of an unsteady Computational Fluid Dynamics model using high-speed imaging.

    Science.gov (United States)

    Boutsioukis, C; Verhaagen, B; Versluis, M; Kastrinakis, E; van der Sluis, L W M

    2010-05-01

    To compare the results of a Computational Fluid Dynamics (CFD) simulation of the irrigant flow within a prepared root canal, during final irrigation with a syringe and a needle, with experimental high-speed visualizations and theoretical calculations of an identical geometry and to evaluate the effect of off-centre positioning of the needle inside the root canal. A CFD model was created to simulate irrigant flow from a side-vented needle inside a prepared root canal. Calculations were carried out for four different positions of the needle inside a prepared root canal. An identical root canal model was made from poly-dimethyl-siloxane (PDMS). High-speed imaging of the flow seeded with particles and Particle Image Velocimetry (PIV) were combined to obtain the velocity field inside the root canal experimentally. Computational, theoretical and experimental results were compared to assess the validity of the computational model. Comparison between CFD computations and experiments revealed good agreement in the velocity magnitude and vortex location and size. Small lateral displacements of the needle inside the canal had a limited effect on the flow field. High-speed imaging experiments together with PIV of the flow inside a simulated root canal showed a good agreement with the CFD model, even though the flow was unsteady. Therefore, the CFD model is able to predict reliably the flow in similar domains.

  8. Learning curves and long-term outcome of simulation-based thoracentesis training for medical students

    Science.gov (United States)

    2011-01-01

    Background Simulation-based medical education has been widely used in medical skills training; however, the effectiveness and long-term outcome of simulation-based training in thoracentesis requires further investigation. The purpose of this study was to assess the learning curve of simulation-based thoracentesis training, study skills retention and transfer of knowledge to a clinical setting following simulation-based education intervention in thoracentesis procedures. Methods Fifty-two medical students were enrolled in this study. Each participant performed five supervised trials on the simulator. Participant's performance was assessed by performance score (PS), procedure time (PT), and participant's confidence (PC). Learning curves for each variable were generated. Long-term outcome of the training was measured by the retesting and clinical performance evaluation 6 months and 1 year, respectively, after initial training on the simulator. Results Significant improvements in PS, PT, and PC were noted among the first 3 to 4 test trials (p 0.05). Clinical competency in thoracentesis was improved in participants who received simulation training relative to that of first year medical residents without such experience (p simulation-based thoracentesis training can significantly improve an individual's performance. The saturation of learning from the simulator can be achieved after four practice sessions. Simulation-based training can assist in long-term retention of skills and can be partially transferred to clinical practice. PMID:21696584

  9. The role of stenosis ratio as a predictor of surgical satisfaction in patients with lumbar spinal canal stenosis: a receiver-operator characteristic (ROC) curve analysis.

    Science.gov (United States)

    Mohammadi, Hassanreza R; Azimi, Parisa; Benzel, Edward C; Shahzadi, Sohrab; Azhari, Shirzad

    2016-09-01

    The aim of this study was to elucidate independent factors that predict surgical satisfaction in lumbar spinal canal stenosis (LSCS) patients. Patients who underwent surgery were grouped based on the age, gender, duration of symptoms, walking distance, Neurogenic Claudication Outcome Score (NCOS) and the stenosis ratio (SR) described by Lurencin. We recorded on 2-year patient satisfaction using standardized measure. The optimal cut-off points in SR, NCOS and walking distance for predicting surgical satisfaction were estimated from sensitivity and specificity calculations and receiver operator characteristic (ROC) curves. One hundred fifty consecutive patients (51 male, 99 female, mean age 62.4±10.9 years) were followed up for 34±13 months (range 24-49). One, two, three and four level stenosis was observed in 10.7%, 39.3%, 36.0 % and 14.0% of patients, respectively. Post-surgical satisfaction was 78.5% at the 2 years follow up. In ROC curve analysis, the asymptotic significance is less than 0.05 in SR and the optimal cut-off value of SR to predict worsening surgical satisfaction was measured as more than 0.52, with 85.4% sensitivity and 77.4% specificity (AUC 0.798, 95% CI 0.73-0.90; Ppatients with degenerative lumbar stenosis considered for surgical treatment. Using a ROC curve analysis, a radiological feature, the SR, demonstrated superiority in predicting patient satisfaction, compared to functional and clinical characteristics such as walking distance and NCOS.

  10. Cyclic fatigue resistance tests of Nickel-Titanium rotary files using simulated canal and weight loading conditions

    Directory of Open Access Journals (Sweden)

    Ok-In Cho

    2013-02-01

    Full Text Available Objectives This study compared the cyclic fatigue resistance of nickel-titanium (NiTi files obtained in a conventional test using a simulated canal with a newly developed method that allows the application of constant fatigue load conditions. Materials and Methods ProFile and K3 files of #25/.06, #30/.06, and #40/.04 were selected. Two types of testing devices were built to test their fatigue performance. The first (conventional device prescribed curvature inside a simulated canal (C-test, the second new device exerted a constant load (L-test whilst allowing any resulting curvature. Ten new instruments of each size and brand were tested with each device. The files were rotated until fracture and the number of cycles to failure (NCF was determined. The NCF were subjected to one-way ANOVA and Duncan's post-hoc test for each method. Spearman's rank correlation coefficient was computed to examine any association between methods. Results Spearman's rank correlation coefficient (ρ = -0.905 showed a significant negative correlation between methods. Groups with significant difference after the L-test divided into 4 clusters, whilst the C-test gave just 2 clusters. From the L-test, considering the negative correlation of NCF, K3 gave a significantly lower fatigue resistance than ProFile as in the C-test. K3 #30/.06 showed a lower fatigue resistance than K3 #25/.06, which was not found by the C-test. Variation in fatigue test methodology resulted in different cyclic fatigue resistance rankings for various NiTi files. Conclusions The new methodology standardized the load during fatigue testing, allowing determination fatigue behavior under constant load conditions.

  11. Antibacterial Efficacy of a New Sonic Irrigation Device for Root Canal Disinfection.

    Science.gov (United States)

    Neuhaus, Klaus W; Liebi, Melanie; Stauffacher, Simone; Eick, Sigrun; Lussi, Adrian

    2016-12-01

    Passive ultrasonic irrigation (PUI) is the most widespread method used to activate irrigation solutions. Concerns have been raised that PUI is less effective in curved root canals and is not passive at all. Our aim was to compare a novel passive sonic irrigation (PSI) device (6000 Hz) with PUI and manual irrigation (MI) with respect to their efficiency in removing different endodontic microorganisms from curved and straight root canals. We performed 2 experiments as follows. In a 3-day infection model, we included 8 groups of single or dual microbial species that were rinsed with 0.9% sodium chloride using PSI, PUI, or MI. Colony-forming units (CFUs) were counted after incubation, and log 10 transformations were performed for statistical comparisons. In a 21-d infection model, we tested the same irrigation protocols on 4 groups of microorganisms and used 1.5% sodium hypochlorite as an irrigant. Infection control samples were taken at day 0, 3, 5, and 7 after treatment and were subsequently reincubated. Using sodium chloride as an irrigant, the amount of reduction in CFUs compared with the negative control was approximately 3 log 10 units for PSI at 6000 Hz, 2 log 10 units for PUI, and 1 log 10 unit for MI. PSI reduced the microorganism CFUs significantly better than PUI. Using sodium hypochlorite led to a significant reduction in microorganism CFUs even with MI. After 3 days, compared with MI, microorganism regrowth significantly reduced after PSI and PUI treatment, but in these groups, in at least half of the samples, microorganisms were detectable after 7 days. PSI at 6000 Hz might be at least equal to PUI with respect to reduction of the microbial load in curved and straight root canals. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  12. The use of plastic models for teaching root canal cleansing and shaping

    Directory of Open Access Journals (Sweden)

    Eftekhar B

    2004-02-01

    Full Text Available The use of root canal models in endodontics education is of high importance. So, in this article"na new method is presented that the students can produce these models with simple and low cost"ninstruments."nThese plastic models are made of polyester which is low cost, available and has the approximate cutting"nproperties of dentin. The best molds were disposable syringes due to their low cost, availability and"nproducing smooth surfaces on polyester models. A spreader with desired curve and tapering is used for"nproducing canals. Rockwell A hardness coefficient of polyester is "33", which is near dentin "31" and"nforeign made models "35.5". Since these polyester models can tolerate up to 280°C and have acceptable"nresistance to chloroform, all root canal therapy techniques such as vertical condensation and retreatments"nare practicable. Their transparency encourage the students to work on them. As a result, the use of these"nmodels is recommended for endodontics training.

  13. Optodynamic Phenomena During Laser-Activated Irrigation Within Root Canals

    Science.gov (United States)

    Lukač, Nejc; Gregorčič, Peter; Jezeršek, Matija

    2016-07-01

    Laser-activated irrigation is a powerful endodontic treatment for smear layer, bacteria, and debris removal from the root canal. In this study, we use shadow photography and the laser-beam-transmission probe to examine the dynamics of laser-induced vapor bubbles inside a root canal model and compare ultrasonic needle irrigation to the laser method. Results confirm important phenomenological differences in the two endodontic methods with the laser method resulting in much deeper irrigation. Observations of simulated debris particles show liquid vorticity effects which in our opinion represents the major cleaning mechanism.

  14. The labyrinthine portion of the facial canal in patients with Bell's palsy investigated by computed tomography

    International Nuclear Information System (INIS)

    Wadin, K.; Thomander, L.; Wilbrand, H.

    1987-01-01

    The reproducibility of the labyrinthine portion of the facial canal by computed tomography was investigated in 22 patients with Bell's palsy. The CT images were compared with those obtained in 18 temporal bone specimens. Measurements of the diameters of different parts of the facial canal were made of these images and also microscopically in plastic casts of the temporal bone specimens. No marked difference was found between the dimensions of the labyrinthine portion of the facial canal of the involved and healthy temporal bone in the patient, nor did these differ from the dimensions in the specimens. CT of the slender, curved labyrinthine portion was found to be of doubtful value for metric estimation of small differences in width. The anatomic variations of the canal rendered the evaluation more difficult. CT with a slice thickness of 2 mm was of no value for assessment of this part of the canal. Measurement of the diameters of the labyrinthine portion on CT images is an inappropriate and unreliable method for clinical purposes. (orig.)

  15. [Root canal treatment of mandibular first premolar with 4 root canals: a case report].

    Science.gov (United States)

    Liu, Xin-yang; Zhan, Fu-Liang

    2015-10-01

    The mandibular first premolar can be considered one of the most challenging teeth to treat, due to the complexity of its root canal morphology and increased incidence of multiple canals. A case of endodontic treatment of a mandibular first premolar exhibiting a total of 4 distinct root canals and 4 apical foramina was described. Anatomic variation of root canal morphology should be considered in endodontic treatment to ensure a favorable healing outcome, and its identification could be enhanced by careful examination using a dental operating microscope. Obturation of root canals using a warm vertical compaction technique with a highly-radiopaque root canal sealer, such as AH Plus, after careful ultrasonic activated irrigation might allow the flow of sealer into the narrowed but unprepared part of the canal, thereby facilitating optimum chemo-mechanical debridement of the root canal system.

  16. Evaluation of Control and Adjustment Structures of the Shibab Main Canal Using HEC-RAS

    Directory of Open Access Journals (Sweden)

    maryam mohammadi

    2017-02-01

    existing structures on the Shibab main canal. HEC-RAS model was prepared by United States army corps of engineers which is developed by the hydrologicengineering center.HEC-RAS analyzes river system and runs under the Windows operating system. This software package is of hydraulic analysis program series, where the user communicates with the system via a graphical user interface (GUI. The system is capable of performing steady and unsteady flow water surfaceprofile calculations. HEC-RAS software is designed to perform one dimensional hydraulic calculation for a full network of natural and synthetic channels. Visits were made before and after the beginning of irrigation, and during the Operation, in order to record the data of the flow and observe the way of utilization of canal, and existing structures. Then, the model was calibrated on the basis of depth and discharge measurement and simulation data in real condition of operation for 10 days impoundment during 21 to 30 April, and the Statistical parameter values:RMSE, EF, MBEand R2 were calculated. Then the objective functionwas evaluatedusingoperational performance indexes of adequacy, efficiency, equity and reliability of Molden and Gates regarding to HEC-RAS simulation results in unsteady condition. Results and Discussion: According to the simulation results in existing condition,theerror of delivery dischargeis equal to 0.54 while applying the management onthe adjustment structure of irrigation networkdeclined theerror to 0.42. By the canal routstructuremanagement in HEC-RAS model, on the basis of proposed operation option, according to existing operation condition, delivery discharge loss in comparison to the total discharge of the network 0.12 value decreases.Based on the simulation results, the mean percentage of improvementin performance indexes of adequacy,efficiency, equity and reliability, as well as objective functionofdelivery discharge are equal to 19.7, 20.90, 66.07, 65.24and54.81. Therefore based on

  17. Cervical shaping in curved root canals: comparison of the efficiency of two endodontic instruments

    OpenAIRE

    Busquim Sandra Soares Kühne; Santos Marcelo dos

    2002-01-01

    The aim of this study was to determine the removal of dentin produced by number 25 (0.08) Flare files (Quantec Flare Series, Analytic Endodontics, Glendora, California, USA) and number 1 e 2 Gates-Glidden burs (Dentsply - Maillefer, Ballaigues, Switzerland), in the mesio-buccal and mesio-lingual root canals, respectively, of extracted human permanent inferior molars, by means of measuring the width of dentinal walls prior and after instrumentation. The obtained values were compared. Due to th...

  18. A Comparative SEM Investigation of Smear Layer Remaining on Dentinal Walls by Three Rotary NiTi Files with Different Cross Sectional Designs in Moderately Curved Canals

    Science.gov (United States)

    Kakkar, Pooja; Vats, Asit

    2015-01-01

    Objective: The objective of this study was to compare the smear layer formed on root canal walls during canal preparation of extracted human teeth by Twisted, Mtwo, and ProTaper rotary nickel titanium instruments. Materials and Methods: Sixty single rooted human premolar teeth with root curvature rotary nickel titanium instruments were used, Twisted (SybronEndo, Orange, CA, USA), Mtwo (VDW, Munich, Germany) and ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) according to manufacturer’s instructions to instrument the root canals. Irrigation for all groups was performed after each instrument change with 3ml of 3% sodium hypochlorite followed by Glyde (File Prep, Dentsply, Maillefer, Ballaigues, Switzerland) as chelator paste and lubricant. Three different areas (coronal, middle and apical thirds) of the root canal were evaluated using scanning electron microscopy (SEM). The canal wall of each sample was assessed and compared using a predefined scale for the presence or absence of smear layer. Data were analysed statistically using ANOVA and Tukey HSD test Results: All three groups showed statistically significant more smear layer in the apical thirds of the canal as compared to the coronal and middle thirds (protary file system produced significantly less smear layer (protary instruments in the apical portion. Twisted Files resulted in less smear layer formation in the apical thirds of the canal compared to ProTaper rotary instruments but were statistically insignificant. Conclusion: Completely clean root canals were not found after instrumentation with any of the three instruments. Under the confines of this study Mtwo instruments produced significantly cleaner dentin wall surfaces throughout the canal length in comparison to Twisted and ProTaper rotary files. Twisted Files proved to be comparable to ProTaper rotary instruments with respect to canal cleanliness in the apical thirds of the root canal. PMID:25954704

  19. MULTIPLE SPINAL CANAL MENINGIOMAS

    Directory of Open Access Journals (Sweden)

    Nandigama Pratap Kumar

    2016-10-01

    Full Text Available BACKGROUND Meningiomas of the spinal canal are common tumours with the incidence of 25 percent of all spinal cord tumours. But multiple spinal canal meningiomas are rare in compare to solitary lesions and account for 2 to 3.5% of all spinal meningiomas. Most of the reported cases are both intra cranial and spinal. Exclusive involvement of the spinal canal by multiple meningiomas are very rare. We could find only sixteen cases in the literature to the best of our knowledge. Exclusive multiple spinal canal meningiomas occurring in the first two decades of life are seldom reported in the literature. We are presenting a case of multiple spinal canal meningiomas in a young patient of 17 years, who was earlier operated for single lesion. We analysed the literature, with illustration of our case. MATERIALS AND METHODS In September 2016, we performed a literature search for multiple spinal canal meningiomas involving exclusively the spinal canal with no limitation for language and publication date. The search was conducted through http://pubmed.com, a wellknown worldwide internet medical address. To the best of our knowledge, we could find only sixteen cases of multiple meningiomas exclusively confined to the spinal canal. Exclusive multiple spinal canal meningiomas occurring in the first two decades of life are seldom reported in the literature. We are presenting a case of multiple spinal canal meningiomas in a young patient of 17 years, who was earlier operated for solitary intradural extra medullary spinal canal meningioma at D4-D6 level, again presented with spastic quadriparesis of two years duration and MRI whole spine demonstrated multiple intradural extra medullary lesions, which were excised completely and the histopathological diagnosis was transitional meningioma. RESULTS Patient recovered from his weakness and sensory symptoms gradually and bladder and bowel symptoms improved gradually over a period of two to three weeks. CONCLUSION Multiple

  20. Comparison of Alterations in the Surface Topographies of HyFlex CM and HyFlex EDM Nickel-titanium Files after Root Canal Preparation: A Three-dimensional Optical Profilometry Study.

    Science.gov (United States)

    Uslu, Gülşah; Özyürek, Taha; Yılmaz, Koray

    2018-01-01

    The aims of the present study were to examine the surface topographies of intact HyFlex CM and HyFlex EDM nickel-titanium files and to compare alterations in the surface topographies of these files after root canal preparation of severely curved canals of molar teeth. Eight HyFlex CM (25/.08) and 8 HyFlex EDM (25/.08) files were included in the present study. In total, 64 severely curved canals of molar teeth, with curvature angles ranging between 50° and 70°, were prepared with HyFlex CM and EDM (n = 32 in each group). Quantitative and qualitative analyses of the files' surface deformation were performed by using three-dimensional optical profilometry before and after root canal preparation. The data were analyzed with the Student t test at the 5% significant level by using SPSS 21.0 software. In the HyFlex EDM group, the qualitative evaluation revealed the presence of cracks and microcavities after use of the file for root canal preparation, whereas only minor surface deformation was observed in the HyFlex CM group. The average roughness, root mean square roughness, and peak to valley height values of the HyFlex EDM group were significantly higher than those of the HyFlex CM group before and after root canal preparation (P EDM group was not statistically significant (P > .5). Within the limitations of the present study, the HyFlex CM files showed significantly higher surface alterations compared with the HyFlex EDM files after the preparation of severely curved root canals. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  1. Nerve canals at the fundus of the internal auditory canal on high-resolution temporal bone CT

    International Nuclear Information System (INIS)

    Ji, Yoon Ha; Youn, Eun Kyung; Kim, Seung Chul

    2001-01-01

    To identify and evaluate the normal anatomy of nerve canals in the fundus of the internal auditory canal which can be visualized on high-resolution temporal bone CT. We retrospectively reviewed high-resolution (1 mm thickness and interval contiguous scan) temporal bone CT images of 253 ears in 150 patients who had not suffered trauma or undergone surgery. Those with a history of uncomplicated inflammatory disease were included, but those with symptoms of vertigo, sensorineural hearing loss, or facial nerve palsy were excluded. Three radiologists determined the detectability and location of canals for the labyrinthine segment of the facial, superior vestibular and cochlear nerve, and the saccular branch and posterior ampullary nerve of the inferior vestibular nerve. Five bony canals in the fundus of the internal auditory canal were identified as nerve canals. Four canals were identified on axial CT images in 100% of cases; the so-called singular canal was identified in only 68%. On coronal CT images, canals for the labyrinthine segment of the facial and superior vestibular nerve were seen in 100% of cases, but those for the cochlear nerve, the saccular branch of the inferior vestibular nerve, and the singular canal were seen in 90.1%, 87.4% and 78% of cases, respectiveIy. In all detectable cases, the canal for the labyrinthine segment of the facial nerve was revealed as one which traversed anterolateralIy, from the anterosuperior portion of the fundus of the internal auditory canal. The canal for the cochlear nerve was located just below that for the labyrinthine segment of the facial nerve, while that canal for the superior vestibular nerve was seen at the posterior aspect of these two canals. The canal for the saccular branch of the inferior vestibular nerve was located just below the canal for the superior vestibular nerve, and that for the posterior ampullary nerve, the so-called singular canal, ran laterally or posteolateralIy from the posteroinferior aspect of

  2. Nerve canals at the fundus of the internal auditory canal on high-resolution temporal bone CT

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Yoon Ha; Youn, Eun Kyung; Kim, Seung Chul [Sungkyunkwan Univ., School of Medicine, Seoul (Korea, Republic of)

    2001-12-01

    To identify and evaluate the normal anatomy of nerve canals in the fundus of the internal auditory canal which can be visualized on high-resolution temporal bone CT. We retrospectively reviewed high-resolution (1 mm thickness and interval contiguous scan) temporal bone CT images of 253 ears in 150 patients who had not suffered trauma or undergone surgery. Those with a history of uncomplicated inflammatory disease were included, but those with symptoms of vertigo, sensorineural hearing loss, or facial nerve palsy were excluded. Three radiologists determined the detectability and location of canals for the labyrinthine segment of the facial, superior vestibular and cochlear nerve, and the saccular branch and posterior ampullary nerve of the inferior vestibular nerve. Five bony canals in the fundus of the internal auditory canal were identified as nerve canals. Four canals were identified on axial CT images in 100% of cases; the so-called singular canal was identified in only 68%. On coronal CT images, canals for the labyrinthine segment of the facial and superior vestibular nerve were seen in 100% of cases, but those for the cochlear nerve, the saccular branch of the inferior vestibular nerve, and the singular canal were seen in 90.1%, 87.4% and 78% of cases, respectiveIy. In all detectable cases, the canal for the labyrinthine segment of the facial nerve was revealed as one which traversed anterolateralIy, from the anterosuperior portion of the fundus of the internal auditory canal. The canal for the cochlear nerve was located just below that for the labyrinthine segment of the facial nerve, while that canal for the superior vestibular nerve was seen at the posterior aspect of these two canals. The canal for the saccular branch of the inferior vestibular nerve was located just below the canal for the superior vestibular nerve, and that for the posterior ampullary nerve, the so-called singular canal, ran laterally or posteolateralIy from the posteroinferior aspect of

  3. The effect of a manual instrumentation technique on five types of premolar root canal geometry assessed by microcomputed tomography and three-dimensional reconstruction

    International Nuclear Information System (INIS)

    Li, Ke-Zeng; Gao, Yuan; Zhang, Ru; Hu, Tao; Guo, Bin

    2011-01-01

    Together with diagnosis and treatment planning, a good knowledge of the root canal system and its frequent variations is a necessity for successful root canal therapy. The selection of instrumentation techniques for variants in internal anatomy of teeth has significant effects on the shaping ability and cleaning effectiveness. The aim of this study was to reveal the differences made by including variations in the internal anatomy of premolars into the study protocol for investigation of a single instrumentation technique (hand ProTaper instruments) assessed by microcomputed tomography and three-dimensional reconstruction. Five single-root premolars, whose root canal systems were classified into one of five types, were scanned with micro-CT before and after preparation with a hand ProTaper instrument. Instrumentation characteristics were measured quantitatively in 3-D using a customized application framework based on MeVisLab. Numeric values were obtained for canal surface area, volume, volume changes, percentage of untouched surface, dentin wall thickness, and the thickness of dentin removed. Preparation errors were also evaluated using a color-coded reconstruction. Canal volumes and surface areas were increased after instrumentation. Prepared canals of all five types were straightened, with transportation toward the inner aspects of S-shaped or multiple curves. However, a ledge was formed at the apical third curve of the type II canal system and a wide range in the percentage of unchanged canal surfaces (27.4-83.0%) was recorded. The dentin walls were more than 0.3 mm thick except in a 1 mm zone from the apical surface and the hazardous area of the type II canal system after preparation with an F3 instrument. The 3-D color-coded images showed different morphological changes in the five types of root canal systems shaped with the same hand instrumentation technique. Premolars are among the most complex teeth for root canal treatment and instrumentation techniques

  4. The effect of a manual instrumentation technique on five types of premolar root canal geometry assessed by microcomputed tomography and three-dimensional reconstruction

    Directory of Open Access Journals (Sweden)

    Hu Tao

    2011-06-01

    Full Text Available Abstract Background Together with diagnosis and treatment planning, a good knowledge of the root canal system and its frequent variations is a necessity for successful root canal therapy. The selection of instrumentation techniques for variants in internal anatomy of teeth has significant effects on the shaping ability and cleaning effectiveness. The aim of this study was to reveal the differences made by including variations in the internal anatomy of premolars into the study protocol for investigation of a single instrumentation technique (hand ProTaper instruments assessed by microcomputed tomography and three-dimensional reconstruction. Methods Five single-root premolars, whose root canal systems were classified into one of five types, were scanned with micro-CT before and after preparation with a hand ProTaper instrument. Instrumentation characteristics were measured quantitatively in 3-D using a customized application framework based on MeVisLab. Numeric values were obtained for canal surface area, volume, volume changes, percentage of untouched surface, dentin wall thickness, and the thickness of dentin removed. Preparation errors were also evaluated using a color-coded reconstruction. Results Canal volumes and surface areas were increased after instrumentation. Prepared canals of all five types were straightened, with transportation toward the inner aspects of S-shaped or multiple curves. However, a ledge was formed at the apical third curve of the type II canal system and a wide range in the percentage of unchanged canal surfaces (27.4-83.0% was recorded. The dentin walls were more than 0.3 mm thick except in a 1 mm zone from the apical surface and the hazardous area of the type II canal system after preparation with an F3 instrument. Conclusions The 3-D color-coded images showed different morphological changes in the five types of root canal systems shaped with the same hand instrumentation technique. Premolars are among the most

  5. Labyrinthine portion of the facial canal in patients with Bell's palsy investigated by computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Wadin, K.; Thomander, L.; Wilbrand, H.

    The reproducibility of the labyrinthine portion of the facial canal by computed tomography was investigated in 22 patients with Bell's palsy. The CT images were compared with those obtained in 18 temporal bone specimens. Measurements of the diameters of different parts of the facial canal were made of these images and also microscopically in plastic casts of the temporal bone specimens. No marked difference was found between the dimensions of the labyrinthine portion of the facial canal of the involved and healthy temporal bone in the patient, nor did these differ from the dimensions in the specimens. CT of the slender, curved labyrinthine portion was found to be of doubtful value for metric estimation of small differences in width. The anatomic variations of the canal rendered the evaluation more difficult. CT with a slice thickness of 2 mm was of no value for assessment of this part of the canal. Measurement of the diameters of the labyrinthine portion on CT images is an inappropriate and unreliable method for clinical purposes.

  6. Scanning electron microscopy investigation of canal cleaning after canal preparation with nickel titanium files

    Directory of Open Access Journals (Sweden)

    Živković Slavoljub

    2010-01-01

    Full Text Available Introduction. Root canal preparation is the most important phase of endodontic procedure and it consists of adequate canal space cleaning and shaping. In recent years, rotary instruments and techniques have gained importance because of the great efficacy, speed and safety of the preparation procedure. Objective. The aim of this research was to investigate the influence of different NiTi files on the canal wall cleaning quality, residual dentine debris and smear layer. Methods. The research was conducted on extracted human teeth in vitro conditions. Teeth were divided in 7 main groups depending on the kind of instruments used for root canal preparation: ProTaper, GT, ProFile, K-3, FlexMaster, hand ProTaper and hand GT. Root canal preparation was accomplished by crown-down technique. Prepared samples were assessed on scanning electron microscopy JEOL, JSM-6460 LV. The evaluation of dentine debris was done with 500x magnification, and the evaluation of smear layer with 1,000 times magnification. Quantitive assessment of dentine debris and smear layer was done according to the criteria of Hulsmann. Results. The least amount of debris and smear layer has been found in canals shaped with ProFile instruments, and the largest amount in canals shaped with FlexMaster instruments. Canal cleaning efficacy of hand GT and ProTaper files has been similar to cleaning efficacy of rotary NiTi files. Statistic analysis has shown a significant difference in amount of dentine debris and smear layer on the canal walls between sample groups shaped with different instruments. Conclusion. Completely clean canals have not been found in any tested group of instruments. The largest amount of debris and smear layer has been found in the apical third of all canals. The design and the type of endodontic instruments influence the efficacy of the canal cleaning.

  7. A study on FlexMaster : a Ni-Ti rotary engine driven system for root canal preparation.

    Science.gov (United States)

    Alam, M S; Bashar, A K; Begumr, J A; Kinoshita, J I

    2006-07-01

    In the present study, the effectiveness of recently introduced rotary Nickel Titanium FlexMaster engine driven system was evaluated for cleaning and shaping of root canals in extracted human teeth and compared with that done by the Nickel Titanium Flexofile hand instruments. A total of 40 root canals from 36 extracted mandibular and maxillary teeth with curvature ranging between 20 and 30 degree were divided into two groups, consisting 20 canals in each. FlexMaster instrumentation was done in 20 canals, using crown-down technique and manual filing with Flexofile was done in other 20 canals, using conventional and step-back techniques. 5.25% sodium hypochlorite (NaOCl) solution and 17% ethelene di-amine tetra-acetic acid (EDTA) were used alternatively for irrigation after canal preparation by each instrument size. Time needed for canal preparation of individual canal was recorded. A procedural error such as instrument breakage was also noted. After preparation, all the roots were cut longitudinally by using diamond burs in turbine handpiece and examined under scanning electron microscope. Apical region was quantified for debris and smear layer based on a 5-score numerical evaluation scale. The data established for scoring the debris and smear layer and preparation time of individual canal were analyzed statistically using the Mann-Whitney U test. Completely cleaned root canals were not found with any of the two instruments and none of the instruments maintained the original canal uniformity and regular dentine surface. Because significantly less debris was found in the apical region using the manual filing technique (p< 0.05). Thus the flexmaster system was found to produce less cleaner root canal walls than manual technique. Only one FlexMaster finishing file sized 30 was separated in the apical region during preparation of 30 degree curved canal. The time taken by FlexMaster was significantly better (p< 0.01) than that of hand instruments.

  8. An analytical mechanical model to describe the response of NiTi rotary endodontic files in a curved root canal.

    Science.gov (United States)

    Leroy, Agnès Marie Françoise; Bahia, Maria Guiomar de Azevedo; Ehrlacher, Alain; Buono, Vicente Tadeu Lopes

    2012-08-01

    To build a mathematical model describing the mechanical behavior of NiTi rotary files while they are rotating in a root canal. The file was seen as a beam undergoing large transformations. The instrument was assumed to be rotating steadily in the root canal, and the geometry of the canal was considered as a known parameter of the problem. The formulae of large transformations mechanics then allowed the calculation of the Green-Lagrange strain field in the file. The non-linear mechanical behavior of NiTi was modeled as a continuous piecewise linear function, assuming that the material did not reach plastic deformation. Criteria locating the changes of behavior of NiTi were established and the tension field in the file, and the external efforts applied on it were calculated. The unknown variable of torsion was deduced from the equilibrium equation system using a Coulomb contact law which solved the problem on a cycle of rotation. In order to verify that the model described well reality, three-point bending experiments were managed on superelastic NiTi wires, whose results were compared to the theoretical ones. It appeared that the model gave a good mentoring of the empirical results in the range of bending angles that interested us. Knowing the geometry of the root canal, one is now able to write the equations of the strain and stress fields in the endodontic instrument, and to quantify the impact of each macroscopic parameter of the problem on its response. This should be useful to predict failure of the files under rotating bending fatigue, and to optimize the geometry of the files. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. [Deformations occurring in the apical third of curved root canals during biomechanical preparation using manual impulsion-traction techniques].

    Science.gov (United States)

    Roig Cayón, M; Basilio Monné, J; Canalda Sahli, C

    1990-01-01

    Apical deformations, specially zips and elbows, during instrumentation of the root canals, are studied. The authors study why do they appear, their effect on endodontic therapy, and the way of avoiding them.

  10. The effect of four different irrigation systems in the removal of a root canal sealer.

    Science.gov (United States)

    Grischke, J; Müller-Heine, A; Hülsmann, M

    2014-09-01

    The aim of this study was to compare the efficiency of sonic, ultrasonic, and hydrodynamic devices in the removal of a root canal sealer from the surface and from simulated irregularities of root canals. Fifty-three root canals with two standardized grooves in the apical and coronal parts of longitudinally split roots were covered with AH Plus root canal sealer. Compared were the effects of (control) syringe irrigation, (1) CanalBrush, (2) passive ultrasonic irrigation, (3) EndoActivator, and (4) RinsEndo on the removal of the sealer. The specimens were divided into four groups (N = 12) and one control group (N = 5) via randomization. The amount of remaining sealer in the root canal irregularities was evaluated under a microscope using a 4-grade scoring system, whereas the remaining sealer on the root canal surface was evaluated with a 7-grade scoring system. Passive ultrasonic irrigation is more effective than the other tested irrigation systems or syringe irrigation in removing sealer from root canal walls (p irrigation shows a superior effect on sealer removal from the root canal surface during endodontic retreatment. Cleaning of lateral grooves seems not to be possible with one of the techniques investigated. Incomplete removal of root canal sealer during re-treatment may cause treatment failure. Passive Ultrasonic irrigation seems to be the most effective system to remove sealer from a root canal.

  11. Microcanonical Monte Carlo approach for computing melting curves by atomistic simulations

    OpenAIRE

    Davis, Sergio; Gutiérrez, Gonzalo

    2017-01-01

    We report microcanonical Monte Carlo simulations of melting and superheating of a generic, Lennard-Jones system starting from the crystalline phase. The isochoric curve, the melting temperature $T_m$ and the critical superheating temperature $T_{LS}$ obtained are in close agreement (well within the microcanonical temperature fluctuations) with standard molecular dynamics one-phase and two-phase methods. These results validate the use of microcanonical Monte Carlo to compute melting points, a ...

  12. Endoscopic root canal treatment.

    Science.gov (United States)

    Moshonov, Joshua; Michaeli, Eli; Nahlieli, Oded

    2009-10-01

    To describe an innovative endoscopic technique for root canal treatment. Root canal treatment was performed on 12 patients (15 teeth), using a newly developed endoscope (Sialotechnology), which combines an endoscope, irrigation, and a surgical microinstrument channel. Endoscopic root canal treatment of all 15 teeth was successful with complete resolution of all symptoms (6-month follow-up). The novel endoscope used in this study accurately identified all microstructures and simplified root canal treatment. The endoscope may be considered for use not only for preoperative observation and diagnosis but also for active endodontic treatment.

  13. Comparative Analysis of Canal Centering Ability of Different Single File Systems Using Cone Beam Computed Tomography- An In-Vitro Study.

    Science.gov (United States)

    Agarwal, Rolly S; Agarwal, Jatin; Jain, Pradeep; Chandra, Anil

    2015-05-01

    The ability of an endodontic instrument to remain centered in the root canal system is one of the most important characteristic influencing the clinical performance of a particular file system. Thus, it is important to assess the canal centering ability of newly introduced single file systems before they can be considered a viable replacement of full-sequence rotary file systems. The aim of the study was to compare the canal transportation, centering ability, and time taken for preparation of curved root canals after instrumentation with single file systems One Shape and Wave One, using cone-beam computed tomography (CBCT). Sixty mesiobuccal canals of mandibular molars with an angle of curvature ranging from 20(o) to 35(o) were divided into three groups of 20 samples each: ProTaper PT (group I) - full-sequence rotary control group, OneShape OS (group II)- single file continuous rotation, WaveOne WO - single file reciprocal motion (group III). Pre instrumentation and post instrumentation three-dimensional CBCT images were obtained from root cross-sections at 3mm, 6mm and 9mm from the apex. Scanned images were then accessed to determine canal transportation and centering ability. The data collected were evaluated using one-way analysis of variance (ANOVA) with Tukey's honestly significant difference test. It was observed that there were no differences in the magnitude of transportation between the rotary instruments (p >0.05) at both 3mm as well as 6mm from the apex. At 9 mm from the apex, Group I PT showed significantly higher mean canal transportation and lower centering ability (0.19±0.08 and 0.39±0.16), as compared to Group II OS (0.12±0.07 and 0.54±0.24) and Group III WO (0.13±0.06 and 0.55±0.18) while the differences between OS and WO were not statistically significant. It was concluded that there was minor difference between the tested groups. Single file systems demonstrated average canal transportation and centering ability comparable to full sequence

  14. Comparative Analysis of Canal Centering Ability of Different Single File Systems Using Cone Beam Computed Tomography- An In-Vitro Study

    Science.gov (United States)

    Agarwal, Jatin; Jain, Pradeep; Chandra, Anil

    2015-01-01

    Background The ability of an endodontic instrument to remain centered in the root canal system is one of the most important characteristic influencing the clinical performance of a particular file system. Thus, it is important to assess the canal centering ability of newly introduced single file systems before they can be considered a viable replacement of full-sequence rotary file systems. Aim The aim of the study was to compare the canal transportation, centering ability, and time taken for preparation of curved root canals after instrumentation with single file systems One Shape and Wave One, using cone-beam computed tomography (CBCT). Materials and Methods Sixty mesiobuccal canals of mandibular molars with an angle of curvature ranging from 20o to 35o were divided into three groups of 20 samples each: ProTaper PT (group I) – full-sequence rotary control group, OneShape OS (group II)- single file continuous rotation, WaveOne WO – single file reciprocal motion (group III). Pre instrumentation and post instrumentation three-dimensional CBCT images were obtained from root cross-sections at 3mm, 6mm and 9mm from the apex. Scanned images were then accessed to determine canal transportation and centering ability. The data collected were evaluated using one-way analysis of variance (ANOVA) with Tukey’s honestly significant difference test. Results It was observed that there were no differences in the magnitude of transportation between the rotary instruments (p >0.05) at both 3mm as well as 6mm from the apex. At 9 mm from the apex, Group I PT showed significantly higher mean canal transportation and lower centering ability (0.19±0.08 and 0.39±0.16), as compared to Group II OS (0.12±0.07 and 0.54±0.24) and Group III WO (0.13±0.06 and 0.55±0.18) while the differences between OS and WO were not statistically significant Conclusion It was concluded that there was minor difference between the tested groups. Single file systems demonstrated average canal

  15. Influence of operator's experience on root canal shaping ability with a rotary nickel-titanium single-file reciprocating motion system.

    Science.gov (United States)

    Muñoz, Estefanía; Forner, Leopoldo; Llena, Carmen

    2014-04-01

    The aim of this study was to evaluate the influence of the operator's experience on the shaping of double-curvature simulated root canals with a nickel-titanium single-file reciprocating motion system. Sixty double-curvature root canals simulated in methacrylate blocks were prepared by 10 students without any experience in endodontics and by 10 professionals who had studied endodontics at the postgraduate level. The Reciproc-VDW system's R25 file was used in the root canal preparation. The blocks were photographed before and after the instrumentation, and the time of instrumentation was also evaluated. Changes in root canal dimensions were analyzed in 6 positions. Significant differences (P file reciprocating motion system Reciproc is not seen to be influenced by the operator's experience regarding the increase of the canal area. Previous training and the need to acquire experience are important in the use of this system, in spite of its apparent simplicity. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  16. Optimization of ISOL targets based on Monte-Carlo simulations of ion release curves

    International Nuclear Information System (INIS)

    Mustapha, B.; Nolen, J.A.

    2003-01-01

    A detailed model for simulating release curves from ISOL targets has been developed. The full 3D geometry is implemented using Geant-4. Produced particles are followed individually from production to release. The delay time is computed event by event. All processes involved: diffusion, effusion and decay are included to obtain the overall release curve. By fitting to the experimental data, important parameters of the release process (diffusion coefficient, sticking time, ...) are extracted. They can be used to improve the efficiency of existing targets and design new ones more suitable to produce beams of rare isotopes

  17. Optimization of ISOL targets based on Monte-Carlo simulations of ion release curves

    CERN Document Server

    Mustapha, B

    2003-01-01

    A detailed model for simulating release curves from ISOL targets has been developed. The full 3D geometry is implemented using Geant-4. Produced particles are followed individually from production to release. The delay time is computed event by event. All processes involved: diffusion, effusion and decay are included to obtain the overall release curve. By fitting to the experimental data, important parameters of the release process (diffusion coefficient, sticking time, ...) are extracted. They can be used to improve the efficiency of existing targets and design new ones more suitable to produce beams of rare isotopes.

  18. Decreased levels of matrix metalloproteinase-2 in root-canal exudates during root canal treatment.

    Science.gov (United States)

    Pattamapun, Kassara; Handagoon, Sira; Sastraruji, Thanapat; Gutmann, James L; Pavasant, Prasit; Krisanaprakornkit, Suttichai

    2017-10-01

    To determine the matrix metalloproteinase-2 (MMP-2) levels in root-canal exudates from teeth undergoing root-canal treatment. The root-canal exudates from six teeth with normal pulp and periradicular tissues that required intentional root canal treatment for prosthodontic reasons and from twelve teeth with pulp necrosis and asymptomatic apical periodontitis (AAP) were sampled with paper points for bacterial culture and aspirated for the detection of proMMP-2 and active MMP-2 by gelatin zymography and the quantification of MMP-2 levels by ELISA. By gelatin zymography, both proMMP-2 and active MMP-2 were detected in the first collection of root-canal exudates from teeth with pulp necrosis and AAP, but not from teeth with normal pulp, and their levels gradually decreased and disappeared at the last collection. Consistently, ELISA demonstrated a significant decrease in MMP-2 levels in the root-canal exudates of teeth with pulp necrosis and AAP following root canal procedures (papical lesions, similar to the clinical application of MMP-8 as a biomarker. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Non-destructive, preclinical evaluation of root canal anatomy of human teeth with flat-panel detector volume CT (FD-VCT)

    International Nuclear Information System (INIS)

    Heidrich, G.; Hassepass, F.; Dullin, C.; Grabbe, E.; Attin, T.; Hannig, C.

    2005-01-01

    Purpose: Successful endodontic diagnostics and therapy call for adequate depiction of the root canal anatomy with multimodal diagnostic imaging. The aim of the present study is to evaluate visualization of the endodont with flat-panel detector volume CT (FD-VCT). Materials and methods: 13 human teeth were examined with the prototype of a FD-VCT. After data acquisition and generation of volume data sets in volume rendering technology (VRT), the findings obtained were compared to conventional X-rays and cross-section preparations of the teeth. Results: The anatomical structures of the endodont such as root canals, side canals and communications between different root canals as well as dentricles could be detected precisely with FD-VCT. The length of curved root canals was also determined accurately. The spatial resolution of the system is around 140 μm. Only around 73% of the main root canals detected with FD-VCT and 87% of the roots could be visualized with conventional dental X-rays. None of the side canals, shown with FD-VCT, was detectable on conventional X-rays. In all cases the enamel and dentin of the teeth could be well delineated. No differences in image quality could be discerned between stored and freshly extracted teeth, or between primary and adult teeth. (orig.)

  20. Endodontic complications of root canal therapy performed by dental students with stainless-steel K-files and nickel-titanium hand files.

    Science.gov (United States)

    Pettiette, M T; Metzger, Z; Phillips, C; Trope, M

    1999-04-01

    Straightening of curved canals is one of the most common procedural errors in endodontic instrumentation. This problem is commonly encountered when dental students perform molar endodontics. The purpose of this study was to compare the effect of the type of instrument used by these students on the extent of straightening and on the incidence of other endodontic procedural errors. Nickel-titanium 0.02 taper hand files were compared with traditional stainless-steel 0.02 taper K-files. Sixty molar teeth comprised of maxillary and mandibular first and second molars were treated by senior dental students. Instrumentation was with either nickel-titanium hand files or stainless-steel K-files. Preoperative and postoperative radiographs of each tooth were taken using an XCP precision instrument with a customized bite block to ensure accurate reproduction of radiographic angulation. The radiographs were scanned and the images stored as TIFF files. By superimposing tracings from the preoperative over the postoperative radiographs, the degree of deviation of the apical third of the root canal filling from the original canal was measured. The presence of other errors, such as strip perforation and instrument breakage, was established by examining the radiographs. In curved canals instrumented by stainless-steel K-files, the average deviation of the apical third of the canals was 14.44 degrees (+/- 10.33 degrees). The deviation was significantly reduced when nickel-titanium hand files were used to an average of 4.39 degrees (+/- 4.53 degrees). The incidence of other procedural errors was also significantly reduced by the use of nickel-titanium hand files.

  1. Cyclic fatigue of nickel-titanium rotary instruments in a double (S-shaped) simulated curvature.

    Science.gov (United States)

    Al-Sudani, Dina; Grande, Nicola M; Plotino, Gianluca; Pompa, Giorgio; Di Carlo, Stefano; Testarelli, Luca; Gambarini, Gianluca

    2012-07-01

    The goal of the present study was to test the fatigue resistance of nickel-titanium rotary files in a double curvature (S-shaped) artificial root canal and to compare those results with single curvature artificial root canals. Two nickel-titanium endodontic instruments consisting of identical instrument sizes (constant .06 taper and 0.25 tip diameter) were tested, ProFile instruments and Vortex instruments. Both instruments were tested for fatigue inside an artificial canal with a double curvature and inside a curved artificial canal with a single curvature. Ten instruments for each group were tested to fracture in continuous rotary motion at 300 rpm. Number of cycles to failure (NCF) was calculated to the nearest whole number, and the length of the fractured fragment was measured in millimeters. Data were statistically analyzed with a level of significance set at 95% confidence level. The NCF value was always statistically lower in the double curved artificial canal when compared with the single curve (P instruments of the same size of different brand only in the single curve; ProFile registered a mean of 633.5 ± 75.1 NCF, whereas Vortex registered a mean of 548 ± 48.9 NCF. Regardless of the differences between the instruments used in the present study, the results suggest that the more complex is the root canal, the more adverse are the effects on the cyclic fatigue resistance of the instruments. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  2. Intraspinal canal rod migration causing late-onset paraparesis 8 years after scoliosis surgery.

    Science.gov (United States)

    Obeid, Ibrahim; Vital, Jean-Marc; Aurouer, Nicolas; Hansen, Steve; Gangnet, Nicolas; Pointillart, Vincent; Gille, Olivier; Boissiere, Louis; Quraishi, Nasir A

    2016-07-01

    Complete intraspinal canal rod migration with posterior bone reconstitution has never been described in the adolescent idiopathic scoliosis (AIS) population. We present an unusual but significant delayed neurological complication after spinal instrumentation surgery. A 24-year-old woman presented with lower limb weakness (ASIA D) 8 years after posterior instrumentation from T2 to L4 for AIS. CT scan and MRI demonstrated intra-canal rod migration with complete laminar reconstitution. The C-reactive protein was slightly elevated (fluctuated between 10 and 20 mg/l). Radiographs showed the convex rod had entered the spinal canal. The patient was taken into the operating room for thoracic spinal decompression and removal of the convex rod. This Cotrel-Dubousset rod, which had been placed on the convexity of the thoracic curve had completely entered the canal from T5 to T10 and was totally covered by bone with the eroded laminae entirely healed and closed. There was no pseudarthrosis. Intra-operatively, the fusion mass was opened along the whole length of this rod and the rod carefully removed and the spinal cord decompressed. The bacteriological cultures returned positive for Propionibacterium acnes. The patient recovered fully within 2 months post-operatively. We opine that the progressive laminar erosion with intra-canal rod migration resulted from mechanical and infectious-related factors. The very low virulence of the strain of Propionibacterium acnes is probably involved in this particular presentation where the rod was trapped in the canal, owing to the quite extensive laminar reconstitution.

  3. Design of canals

    CERN Document Server

    Swamee, P K

    2015-01-01

    The book presents firsthand material from the authors on design of hydraulic canals. The book discusses elements of design based on principles of hydraulic flow through canals. It covers optimization of design based on usage requirements and economic constraints. The book includes explicit design equations and design procedures along with design examples for varied cases. With its comprehensive coverage of the principles of hydraulic canal design, this book will prove useful to students, researchers, and practicing engineers. End-of-chapter pedagogical elements make it ideal for use in graduate courses on hydraulic structures offered by most civil engineering departments across the world.

  4. An evaluation of canal curvature at the apical one third in type II mesial canals of mandibular molars

    Directory of Open Access Journals (Sweden)

    Hye-Rim Yun

    2012-05-01

    Full Text Available Objectives The purpose of this study was to evaluate the buccolingual curvature at the apical one third in type II mesial canals of mandibular molars using the radius and angle of curvature. Materials and Methods Total 100 mandibular molars were selected. Following an endodontic access in the teeth, their distal roots were removed. #15 H- or K-files (Dentsply Maillefer were inserted into the mesiobuccal and mesiolingual canals of the teeth. Radiographs of the teeth were taken for the proximal view. Among them, type II canals were selected and divided into two subgroups, IIa and IIb. In type IIa, two separate canals merged into one canal before reaching the apex and in type IIb, two separate canals merged into one canal within the apical foramen. The radius and angle of curvature of specimens were examined. Results In type II, mean radius of curvature in mesiolingual and mesiobuccal canals were 2.82 mm and 3.58 mm, respectively. The radius of the curvature of mesiolingual canals were significantly smaller than that of mesiobuccal canals in type II, and especially in type IIa. However, there were no statistically significant differences in radius of curvature between mesiobuccal and mesiolingual canals in type IIb and there were no significant differences in angle of curvature between type IIa and IIb. Conclusion In this study, type II mesial canals of mandibular molars showed severe curvature in the proximal view. Especially, mesiolingual canals of type IIa had more abrupt curvature than mesiobuccal canals at the apical one third.

  5. Osmolarity and root canal antiseptics.

    Science.gov (United States)

    Rossi-Fedele, G; Guastalli, A R

    2014-04-01

    Antiseptics used in endodontics for disinfection purposes include root canal dressings and irrigants. Osmotic shock is known to cause the alteration of microbial cell viability and might have a role in the mechanism of action of root canal antiseptics. The aim of this review was to determine the role of osmolarity on the performance of antiseptics in root canal treatment. A literature search using the Medline electronic database was conducted up to 30 May 2013 using the following search terms and combinations: 'osmolarity AND root canal or endodontic or antiseptic or irrigation or irrigant or medication or dressing or biofilm; osmolality AND root canal or endodontic or antiseptic or irrigation or irrigant or medication or dressing or biofilm; osmotic AND root canal or endodontic or antiseptic or irrigation or irrigant or medication or dressing or biofilm; osmosis AND root canal or endodontic or antiseptic or irrigation or irrigant or medication or dressing or biofilm; sodium chloride AND root canal or endodontic or antiseptic or irrigation or irrigant or medication or dressing or biofilm'. Publications were included if the effects of osmolarity on the clinical performance of antiseptics in root canal treatment were stated, if preparations with different osmolarities values were compared and if they were published in English. A hand search of articles published online, 'in press' and 'early view', and in the reference list of the included papers was carried out following the same criteria. A total of 3274 publications were identified using the database, and three were included in the review. The evidence available in endodontics suggests a possible role for hyperosmotic root canal medicaments as disinfectants, and that there is no influence of osmolarity on the tissue dissolution capacity of sodium hypochlorite. There are insufficient data to obtain a sound conclusion regarding the role of hypo-osmosis in root canal disinfection, or osmosis in any further desirable

  6. An analytical mechanical model to describe the response of NiTi rotary endodontic files in a curved root canal

    Energy Technology Data Exchange (ETDEWEB)

    Leroy, Agnes Marie Francoise [Department of Metallurgical and Materials Engineering, School of Engineering, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Department of Mechanical and Materials Engineering, Ecole des Ponts Paristech (ENPC), Champs-sur-Marne (France); Bahia, Maria Guiomar de Azevedo [Department of Restorative Dentistry, Faculty of Dentistry, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Ehrlacher, Alain [Department of Mechanical and Materials Engineering, Ecole des Ponts Paristech (ENPC), Champs-sur-Marne (France); Buono, Vicente Tadeu Lopes, E-mail: vbuono@demet.ufmg.br [Department of Metallurgical and Materials Engineering, School of Engineering, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)

    2012-08-01

    Aim: To build a mathematical model describing the mechanical behavior of NiTi rotary files while they are rotating in a root canal. Methodology: The file was seen as a beam undergoing large transformations. The instrument was assumed to be rotating steadily in the root canal, and the geometry of the canal was considered as a known parameter of the problem. The formulae of large transformations mechanics then allowed the calculation of the Green-Lagrange strain field in the file. The non-linear mechanical behavior of NiTi was modeled as a continuous piecewise linear function, assuming that the material did not reach plastic deformation. Criteria locating the changes of behavior of NiTi were established and the tension field in the file, and the external efforts applied on it were calculated. The unknown variable of torsion was deduced from the equilibrium equation system using a Coulomb contact law which solved the problem on a cycle of rotation. Results: In order to verify that the model described well reality, three-point bending experiments were managed on superelastic NiTi wires, whose results were compared to the theoretical ones. It appeared that the model gave a good mentoring of the empirical results in the range of bending angles that interested us. Conclusions: Knowing the geometry of the root canal, one is now able to write the equations of the strain and stress fields in the endodontic instrument, and to quantify the impact of each macroscopic parameter of the problem on its response. This should be useful to predict failure of the files under rotating bending fatigue, and to optimize the geometry of the files. - Highlights: Black-Right-Pointing-Pointer A mechanical model of the behavior of a NiTi endodontic instrument was developed. Black-Right-Pointing-Pointer The model was validated with results of three-point bending tests on NiTi wires. Black-Right-Pointing-Pointer The model is appropriate for the optimization of instruments' geometry.

  7. An analytical mechanical model to describe the response of NiTi rotary endodontic files in a curved root canal

    International Nuclear Information System (INIS)

    Leroy, Agnès Marie Françoise; Bahia, Maria Guiomar de Azevedo; Ehrlacher, Alain; Buono, Vicente Tadeu Lopes

    2012-01-01

    Aim: To build a mathematical model describing the mechanical behavior of NiTi rotary files while they are rotating in a root canal. Methodology: The file was seen as a beam undergoing large transformations. The instrument was assumed to be rotating steadily in the root canal, and the geometry of the canal was considered as a known parameter of the problem. The formulae of large transformations mechanics then allowed the calculation of the Green–Lagrange strain field in the file. The non-linear mechanical behavior of NiTi was modeled as a continuous piecewise linear function, assuming that the material did not reach plastic deformation. Criteria locating the changes of behavior of NiTi were established and the tension field in the file, and the external efforts applied on it were calculated. The unknown variable of torsion was deduced from the equilibrium equation system using a Coulomb contact law which solved the problem on a cycle of rotation. Results: In order to verify that the model described well reality, three-point bending experiments were managed on superelastic NiTi wires, whose results were compared to the theoretical ones. It appeared that the model gave a good mentoring of the empirical results in the range of bending angles that interested us. Conclusions: Knowing the geometry of the root canal, one is now able to write the equations of the strain and stress fields in the endodontic instrument, and to quantify the impact of each macroscopic parameter of the problem on its response. This should be useful to predict failure of the files under rotating bending fatigue, and to optimize the geometry of the files. - Highlights: ► A mechanical model of the behavior of a NiTi endodontic instrument was developed. ► The model was validated with results of three-point bending tests on NiTi wires. ► The model is appropriate for the optimization of instruments' geometry.

  8. Anatomic study on mental canal and incisive nerve canal in interforaminal region in Chinese population.

    Science.gov (United States)

    Xu, Yun; Suo, Ning; Tian, Xiufen; Li, Fei; Zhong, Guangxin; Liu, Xiaoran; Bao, Yongxing; Song, Tao; Tian, Hua

    2015-08-01

    This study was aimed to detect the positions of mental canal and incisive nerve canal as well as the prolongation of mandibular canal in interforaminal region in Chinese population to supply the reference data of the surgical safe zone in chin for clinicians. A total of 80 formalin-fixed semi-mandibles of Chinese adult cadavers were dissected, the positions and courses of mental canal and incisive nerve canal as well as the prolongation of mandibular canal in interforaminal region were measured. The mental foramina were present in all cases (100 %), and most of them were located below 2nd premolar (58.75 %). Accessory mental foramina were observed in 5 %. The anterior end of mandibular canal, extending along the course of 7.37 ± 1.10 mm above the lower border of mandible to interforaminal region about 3.54 ± 0.70 mm medial to the mental foramen, most often ended below between the two premolars (73.75 %), where it continued as the incisive nerve canal (100 %) and the mental canal (96.25 %). Mental canal, with the wall formed by compact bone, being 2.60 ± 0.60 mm in diameter and 4.01 ± 1.20 mm in length, opened into mental foramen. Incisive nerve canal, with the wall formed by thin compact bone and/or partly or completely by spongy bone, being 1.76 ± 0.27 mm in diameter and 24.87 ± 2.23 mm in length, extended to the incisor region along the course of 9.53 ± 1.43 mm above the lower border of mandible, and most often ended below the lateral incisor (70.00 %). This research recommended for chin operations in Chinese population: the surgical safe zone could be set in the region about over 4 mm anterior to the mental foramen, and over 12 mm above inferior border of mandible for anterior alveolar surgery, or within 9 mm above inferior border of mandible for genioplasty.

  9. Periapical repair after root canal filling with different root canal sealers.

    Science.gov (United States)

    Tanomaru-Filho, Mário; Tanomaru, Juliane Maria Guerreiro; Leonardo, Mario Roberto; da Silva, Lea Assed Bezerra

    2009-01-01

    The aim of this study was to evaluate periapical repair after root canal filling with different endodontic sealers. Sixty-four root canals from dog s teeth were filled, divided into 4 groups (n=16). Root canals were instrumented with K-type files and irrigated with 1% sodium hypochlorite solution. Root canals were filled in the same session by active lateral condensation of the cones and sealers: Intrafill, AH Plus, Roeko Seal and Resilon/Epiphany System. After 90 days, the animals were euthanized and the tissues to be evaluated were processed and stained with hematoxylin and eosin. For histopathological analysis, the following parameters were evaluated: inflammatory process, mineralized tissue resorption, and apical mineralized tissue deposition. Histopathological analysis demonstrated that Intrafill had less favorable results in terms of apical and periapical repair, compared to the other sealers (p0.05). In conclusion, AH Plus and the materials Roeko Seal and Epiphany are good options for clinical use in Endodontics.

  10. Posterior semicircular canal dehiscence: a morphologic cause of vertigo similar to superior semicircular canal dehiscence

    International Nuclear Information System (INIS)

    Krombach, G.A.; Schmitz-Rode, T.; Haage, P.; Guenther, R.W.; DiMartino, E.; Prescher, A.; Kinzel, S.

    2003-01-01

    Heading Abstract.The aim of this study was to assess imaging findings of posterior semicircular dehiscence on computed tomography and to evaluate incidence of posterior and superior semicircular canal dehiscence in patients presenting with vertigo, sensorineuronal hearing loss or in a control group without symptoms related to the inner ear. Computed tomography was performed in 507 patients presenting either with vertigo (n=128; 23 of these patients suffered also from sensorineuronal hearing loss), other symptoms related to the inner ear, such as hearing loss or tinnitus (n=183) or symptoms unrelated to the labyrinth (n=196). All images were reviewed for presence of dehiscence of the bone, overlying the semicircular canals. Twenty-nine patients had superior semicircular canal dehiscence. Of these patients, 83% presented with vertigo, 10% with hearing loss or tinnitus and the remaining 7% with symptoms unrelated to the inner ear. In 23 patients dehiscence of the posterior semicircular canal was encountered. Of these patients, 86% presented with vertigo, 9% with hearing loss or tinnitus and 5% with symptoms unrelated to the inner ear. Defects of the bony overly are found at the posterior semicircular canal, in addition to the recently introduced superior canal dehiscence syndrome. Significant prevalence of vertigo in these patients suggests that posterior semicircular canal dehiscence can cause vertigo, similar to superior semicircular canal dehiscence. (orig.)

  11. Posterior semicircular canal dehiscence: a morphologic cause of vertigo similar to superior semicircular canal dehiscence

    Energy Technology Data Exchange (ETDEWEB)

    Krombach, G A; Schmitz-Rode, T; Haage, P; Guenther, R W [Department of Diagnostic Radiology, University of Technology, Pauwelstrasse 30, 52057, Aachen (Germany); DiMartino, E [Department of Otorhinolaryngology, University of Technology, Pauwelstrasse 30, 52057, Aachen (Germany); Prescher, A [Department of Anatomy, University of Technology, Pauwelstrasse 30, 52057, Aachen (Germany); Kinzel, S [Department of Experimental Veterinarian Medicine, University of Technology, Pauwelstrasse 30, 52057, Aachen (Germany)

    2003-06-01

    Heading Abstract.The aim of this study was to assess imaging findings of posterior semicircular dehiscence on computed tomography and to evaluate incidence of posterior and superior semicircular canal dehiscence in patients presenting with vertigo, sensorineuronal hearing loss or in a control group without symptoms related to the inner ear. Computed tomography was performed in 507 patients presenting either with vertigo (n=128; 23 of these patients suffered also from sensorineuronal hearing loss), other symptoms related to the inner ear, such as hearing loss or tinnitus (n=183) or symptoms unrelated to the labyrinth (n=196). All images were reviewed for presence of dehiscence of the bone, overlying the semicircular canals. Twenty-nine patients had superior semicircular canal dehiscence. Of these patients, 83% presented with vertigo, 10% with hearing loss or tinnitus and the remaining 7% with symptoms unrelated to the inner ear. In 23 patients dehiscence of the posterior semicircular canal was encountered. Of these patients, 86% presented with vertigo, 9% with hearing loss or tinnitus and 5% with symptoms unrelated to the inner ear. Defects of the bony overly are found at the posterior semicircular canal, in addition to the recently introduced superior canal dehiscence syndrome. Significant prevalence of vertigo in these patients suggests that posterior semicircular canal dehiscence can cause vertigo, similar to superior semicircular canal dehiscence. (orig.)

  12. Unpredictable Root Canal Morphology: Expect the Unexpected

    Directory of Open Access Journals (Sweden)

    Sohez J Makani

    2015-01-01

    Full Text Available Background: A maxillary first molar with more than four canals is an interesting example of anatomic variations, especially when two of these canals are detected, with separate apical foramen in the distal root. The inability to locate the unexpected canals of various anatomical configuration and subsequently treat them , may lead to therapeutic failures. Endodontic retreatment is usually the modality of choice in such cases. This report describes a case of a maxillary first molar with five canals (two mesial canals in mesial root, two distal canals in two distal roots and a palatal canal in palatal root. Additionally it shows a rare anatomic configuration and emphasizes the importance of identifying additional canals.

  13. Quantifying canal leakage rates using a mass-balance approach and heat-based hydraulic conductivity estimates in selected irrigation canals, western Nebraska, 2007 through 2009

    Science.gov (United States)

    Hobza, Christopher M.; Andersen, Michael J.

    2010-01-01

    The water supply in areas of the North Platte River Basin in the Nebraska Panhandle has been designated as fully appropriated or overappropriated by the Nebraska Department of Natural Resources (NDNR). Enacted legislation (Legislative Bill 962) requires the North Platte Natural Resources District (NPNRD) and the NDNR to develop an Integrated Management Plan (IMP) to balance groundwater and surface-water supply and demand in the NPNRD. A clear understanding of the groundwater and surface-water systems is critical for the development of a successful IMP. The primary source of groundwater recharge in parts of the NPNRD is from irrigation canal leakage. Because canal leakage constitutes a large part of the hydrologic budget, spatially distributing canal leakage to the groundwater system is important to any management strategy. Surface geophysical data collected along selected reaches of irrigation canals has allowed for the spatial distribution of leakage on a relative basis; however, the actual magnitude of leakage remains poorly defined. To address this need, the U.S. Geological Survey, in cooperation with the NPNRD, established streamflow-gaging stations at upstream and downstream ends from two selected canal reaches to allow a mass-balance approach to be used to calculate daily leakage rates. Water-level and sediment temperature data were collected and simulated at three temperature monitoring sites to allow the use of heat as a tracer to estimate the hydraulic conductivity of canal bed sediment. Canal-leakage rates were estimated by applying Darcy's Law to modeled vertical hydraulic conductivity and either the estimated or measured hydraulic gradient. This approach will improve the understanding of the spatial and temporal variability of canal leakage in varying geologic settings identified in capacitively coupled resistivity surveys. The high-leakage potential study reach of the Tri-State Canal had two streamflow-gaging stations and two temperature monitoring

  14. Scanning electron microscopic evaluation of the influence of manual and mechanical glide path on the surface of nickel-titanium rotary instruments in moderately curved root canals: An in-vivo study

    Science.gov (United States)

    Patel, Dishant; Bashetty, Kusum; Srirekha, A.; Archana, S.; Savitha, B.; Vijay, R.

    2016-01-01

    Aim: The aim of this study was to evaluate the influence of manual versus mechanical glide path (GP) on the surface changes of two different nickel-titanium rotary instruments used during root canal therapy in a moderately curved root canal. Materials and Methods: Sixty systemically healthy controls were selected for the study. Controls were divided randomly into four groups: Group 1: Manual GP followed by RaCe rotary instruments, Group 2: Manual GP followed by HyFlex rotary instruments, Group 3: Mechanical GP followed by RaCe rotary instruments, Group 4: Mechanical GP followed by HyFlex rotary instruments. After access opening, GP was prepared and rotary instruments were used according to manufacturer's instructions. All instruments were evaluated for defects under standard error mean before their use and after a single use. The scorings for the files were given at apical and middle third. Statistical Analysis Used: Chi-squared test was used. Results: The results showed that there is no statistical difference between any of the groups. Irrespective of the GP and rotary files used, more defects were present in the apical third when compared to middle third of the rotary instrument. Conclusion: Within the limitations of this study, it can be concluded that there was no effect of manual or mechanical GP on surface defects of subsequent rotary file system used. PMID:27994317

  15. Study of seepage losses from irrigation canals using radioactive tracer technique

    International Nuclear Information System (INIS)

    Ahmad, M.; Tariq, J.A.; Rashid, A.; Rafiq, M.; Iqbal, N.

    2004-06-01

    Pakistan has an intricate irrigation system comprising a huge network of canals. A significant fraction of water in irrigation canals is lost through seepage, which is further responsible for water logging and salinity in some areas. Government is considering lining of irrigation canals to overcome this twin menace. Due to involvement of huge costs, highly pervious sections where the seepage rate is appreciably high, are needed to be identified for planning and execution of remedial actions to eliminate or minimize seepage losses. The conventional methods of measuring seepage rate from canals are limited to 'ponding' and 'inflow-outflow' methods. The ponding method is usually restricted to small canals because of the costly bulkheads and water requirement, unaffordable closure of canal, non representation of the line source and variation in the rate of seepage loss with time due to the sealing effects of fine sediments settling out. Inaccurate measurement of discharge under field conditions and complication due to diversion do not favour the inflow-outflow method. It is believed that the analytical methods represent the most accurate and convenient means of determining seepage values using accurate insitu hydraulic conductivity of the subsoil determined by radiotracer, geometry of the canal and position of the groundwater. As a practical application, radiotracer experiments were carried out at Rakh branch canal near Sukhiki, District Hafizabad (Punjab) to determine groundwater filtration velocity by single well point dilution technique using Technetium-99m (sup 99m/Tc) radioactive tracer, Hydraulic conductivity (determined from filtration velocity and hydraulic gradient) and canal parameters were used in the parametric equation of parachute curve to estimate the seepage rate. The average seepage rate was 4.05 cubic meter per day per meter length of the canal (equivalent to 3.795 cusec per million square feet or 1.157 cumec per second per million square meter of

  16. Comparison of effects of ProTaper, HeroShaper, and Gates Glidden Burs on cervical dentin thickness and root canal volume by using multislice computed tomography.

    Science.gov (United States)

    Mahran, Abeer H; AboEl-Fotouh, Mona M

    2008-10-01

    The purpose of this study was to compare the effects of 3 different instruments used to prepare curved root canals on the remaining cervical dentin thickness and total amount of dentin removed from root canals during instrumentation by using multislice computed tomography. Mesiobuccal canals of 45 mandibular first molars with curvature between 30-40 degrees were divided into 3 equal groups: ProTaper, Hero Shaper, and Gates Glidden Bur with Flex-R hand file. Cervical dentin thickness and canal volume were measured before and after instrumentation by using multislice computed tomography and image analysis software. The results indicated that ProTaper removed significantly less cervical dentin from distal wall of the root (dangerous zone) than HeroShaper and Gates Glidden Bur (P ProTaper system (P < .05).

  17. Simulation of time curves in small animal PET using GATE

    International Nuclear Information System (INIS)

    Simon, Luc; Strul, Daniel; Santin, Giovanni; Krieguer, Magalie; Morel, Christian

    2004-01-01

    The ClearPET project of the Crystal Clear Collaboration (CCC) is building spin-off technology for high resolution small animal Positron Emission Tomography (PET). Monte Carlo simulation is essential for optimizing the specifications of these systems with regards to their most important characteristics, such as spatial resolution, sensitivity, or count rate performance. GATE, the Geant4 Application for Tomographic Emission simulates the passing of time during real acquisitions, allowing to handle dynamic systems such as decaying source distributions or moving detectors. GATE output is analyzed on an event-by-event basis. The time associated with each single event allows to sort coincidences and to model dead-time. This leads to the study of time curves for a prospective small animal PET scanner design. The count rates of true, and random coincidences are discussed together with the corresponding Noise Equivalent Count (NEC) rates as a function of some PET scanner specifications such as detector dead time, or coincidence time window

  18. Identification of possible factors impacting dental students' ability to locate MB2 canals in maxillary molars.

    Science.gov (United States)

    Park, Ellen; Chehroudi, Babak; Coil, Jeffrey M

    2014-05-01

    This study examined the effect of the access size and straight-line path of access on third-year dental students' ability to locate a second mesiobuccal (MB2) canal in maxillary first and second molars. One hundred and six third-year dental students at one Faculty of Dentistry performed simulated root canal treatment with the aid of 2x magnification loupes on extracted teeth. A postgraduate endodontic student subsequently made a reasonable search for an untreated MB2 canal with the aid of a dental operating microscope. The mesiobuccal roots were then sectioned horizontally for determination of the canal configuration. The dental students were able to treat an MB2 canal in 15.8 percent of the teeth, but this was not associated with satisfactory access criteria. The postgraduate endodontic student identified an MB2 canal in 54.7 percent of the remaining tooth samples excluding those where the MB2 canal was found by the dental students; this represented 94.3 percent of those teeth confirmed by horizontal sectioning of the root to have an MB2 canal. The postgraduate student troughed, on average, 2.6 mm before negotiating the MB2 canal. As satisfactory access criteria and straight-line path of access did not correlate with the dental students' ability to find a second mesiobuccal canal, this result has important implications for educational goals with respect to endodontic treatment of maxillary molar teeth.

  19. Quality aspects of ex vivo root canal treatments done by undergraduate dental students using four different endodontic treatment systems.

    Science.gov (United States)

    Jungnickel, Luise; Kruse, Casper; Vaeth, Michael; Kirkevang, Lise-Lotte

    2018-04-01

    To evaluate factors associated with treatment quality of ex vivo root canal treatments performed by undergraduate dental students using different endodontic treatment systems. Four students performed root canal treatment on 80 extracted human teeth using four endodontic treatment systems in designated treatment order following a Latin square design. Lateral seal and length of root canal fillings was radiographically assessed; for lateral seal, a graded visual scale was used. Treatment time was measured separately for access preparation, biomechanical root canal preparation, obturation and for the total procedure. Mishaps were registered. An ANOVA mirroring the Latin square design was performed. Use of machine-driven nickel-titanium systems resulted in overall better quality scores for lateral seal than use of the manual stainless-steel system. Among systems with machine-driven files, scores did not significantly differ. Use of machine-driven instruments resulted in shorter treatment time than manual instrumentation. Machine-driven systems with few files achieved shorter treatment times. With increasing number of treatments, root canal-filling quality increased, treatment time decreased; a learning curve was plotted. No root canal shaping file separated. The use of endodontic treatment systems with machine-driven files led to higher quality lateral seal compared to the manual system. The three contemporary machine-driven systems delivered comparable results regarding quality of root canal fillings; they were safe to use and provided a more efficient workflow than the manual technique. Increasing experience had a positive impact on the quality of root canal fillings while treatment time decreased.

  20. Mandibular second premolar with three canals: Re-treatment of a case with unusual root canal anatomy

    Directory of Open Access Journals (Sweden)

    Niranjan Desai

    2011-01-01

    Full Text Available A thorough knowledge of root canal anatomy along with the anatomical variations that may be present is essential for success of endodontic therapy. Unusual presentations in the number of the roots or the canals should be expected in every tooth. Mandibular second premolars are thought of as having a single root and canal. Studies have stated that the prevalence of three canals with three orifices in this tooth is 0.4%. The mandibular second premolar is particularly difficult to treat owing to the fact that a wide variation in the number, location and curvature of the roots and canals exist. Added to this is the fact that the access opening is restricted and location of the lingually placed orifices is difficult. This case report details the re-treatment of a mandibular second premolar with three canals and three separate orifices using the surgical microscope.

  1. A Low-Cost Teaching Model of Inguinal Canal: A Useful Method to Teach Surgical Concepts in Hernia Repair

    Science.gov (United States)

    Ansaloni, Luca; Catena, Fausto; Coccolini, Frederico; Ceresoli, Marco; Pinna, Antonio Daniele

    2014-01-01

    Objectives: Inguinal canal anatomy and hernia repair is difficult for medical students and surgical residents to comprehend. Methods: Using low-cost material, a 3-dimensional inexpensive model of the inguinal canal was created to allow students to learn anatomical details and landmarks and to perform their own simulated hernia repair. In order to…

  2. In vitro comparison rate of dental root canal transportation using two single file systems on the simulated resin blocks

    Directory of Open Access Journals (Sweden)

    Mohammad Javad Etesami

    2016-07-01

    Full Text Available Background and Aims: Cleaning and shaping is one of the most important stages in endodontic treatment. Single-file systems save time and reduce the risk of transmission of pathogens. This in vitro study was aimed to compare the rate of canal transportation after the preparation of the stimulated resin root canal with two single-file systems, namely Waveone and Reciproc. Materials and Methods: Thirty stimulated resin root canal blocks with size 8/0. 02 K file were randomly divided into two study groups. The preparation in Group A and Group B was performed using Reciproc and Waveone files, respectively. Pre and post- preparation photographs were taken and the images were superimposed to evaluate the inner and outer wall’s curvature tendency at three points (apical, middle and coronal using AutoCad pragram. Data were analyzed using T-test. Results: Based on the results, the degree of transportation in the inner and outer walls of the canal was less at the level of 3 millimeters (P0.05. Conclusion: Waveone showed better performance in the middle third of canal and this system maybe recommended.

  3. The enlargement of geniculate fossa of facial nerve canal: a new CT finding of facial nerve canal fracture

    International Nuclear Information System (INIS)

    Gong Ruozhen; Li Yuhua; Gong Wuxian; Wu Lebin

    2006-01-01

    Objective: To discuss the value of enlargement of geniculate fossa of facial nerve canal in the diagnosis of facial nerve canal fracture. Methods: Thirty patients with facial nerve canal fracture underwent axial and coronal CT scan. The correlation between the fracture and the enlargement of geniculate fossa of facial nerve canal was analyzed. The ability of showing the fracture and enlargement of geniculate fossa of facial nerve canal in axial and coronal imaging were compared. Results: Fracture of geniculate fossa of facial nerve canal was found in the operation in 30 patients, while the fracture was detected in CT in 18 patients. Enlargement of geniculate ganglion of facial nerve was detected in 30 patients in the operation, while the enlargement of fossa was found in CT in 28 cases. Enlargement and fracture of geniculate fossa of facial nerve canal were both detected in CT images in 18 patients. Only the enlargement of geniculate fossa of facial nerve canal was shown in 12 patients in CT. Conclusion: Enlargement of geniculate fossa of facial nerve canal was a useful finding in the diagnosis of fracture of geniculate fossa in patients with facial paralysis, even no fracture line was shown on CT images. (authors)

  4. Pair-instability Supernova Simulations: Progenitor Evolution, Explosion, and Light Curves

    Energy Technology Data Exchange (ETDEWEB)

    Gilmer, Matthew S.; Fröhlich, Carla [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Kozyreva, Alexandra [The Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel); Hirschi, Raphael [Astrophysics group, School of Chemical and Physical Sciences, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom); Yusof, Norhasliza, E-mail: msgilmer@ncsu.edu [Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2017-09-10

    In recent years, the viability of the pair-instability supernova (PISN) scenario for explaining superluminous supernovae has all but disappeared except for a few slowly-evolving examples. However, PISNe are not predicted to be superluminous throughout the bulk of their mass range. In fact, it is more likely that the first PISN we see (if we have not seen one already) will not be superluminous. Here, we present hydrodynamic simulations of PISNe for four stellar models with unique envelope properties spanning the PISN mass range. In addition, we compute synthetic light curves (LCs) for comparison with current and future observations. We also investigate, in the context of our most massive model, the prospect of mixing in the supernova ejecta, alleviating discrepancies between current PISN models and the remaining superluminous candidate events. To this end, we present the first published 3D hydrodynamic simulations of PISNe. After achieving convergence between 1D, 2D, and 3D simulations, we examine mixing in the supernova ejecta and its affect on the bolometric LC. We observe slight deviations from spherical symmetry, which increase with the number of dimensions. We find no significant effects on the bolometric LC; however, we conclude that mixing between the silicon and oxygen rich layers caused by the Rayleigh–Taylor instability may affect spectra.

  5. Preliminary Hybrid Modeling of the Panama Canal: Operations and Salinity Diffusion

    Directory of Open Access Journals (Sweden)

    Luis Rabelo

    2012-01-01

    Full Text Available This paper deals with the initial modeling of water salinity and its diffusion into the lakes during lock operation on the Panama Canal. A hybrid operational model was implemented using the AnyLogic software simulation environment. This was accomplished by generating an operational discrete-event simulation model and a continuous simulation model based on differential equations, which modeled the salinity diffusion in the lakes. This paper presents that unique application and includes the effective integration of lock operations and its impact on the environment.

  6. Industrial canal waterfronts in The Netherlands : transforming the canal zones of B5

    NARCIS (Netherlands)

    Curulli, G.I.

    2012-01-01

    Industrial Canal Waterfronts in The Netherlands provides a comprehensive presentation of the characteristics and challenges of five interconnected and dismissed industrial canal zones located in the Dutch Brabant cities of Eindhoven, Breda, Tilburg, s’-Hertogenbosch and Helmond (B5). Through the

  7. Influence of the rotary and/or oscillatory reciprocating systems in the morphological changes of narrow and curved molar root canals anatomy

    Directory of Open Access Journals (Sweden)

    Joedy Maria Costa Santa Rosa

    Full Text Available OBJECTIVE: This study evaluated four mechanized Endodontic systems, ProTaper Universal, K3 Endo, Twisted file (rotary and the oscillatory reciprocating system Endo - Eze TiLOS, in order to verify and measure alterations in original anatomy with deviations at cervical, medium and apical root canal thirds. MATERIAL AND METHOD: It was used MB root canals of 60 extract human lower molars, to produce a line of severe angles, according to the classification of Schneider. Samples were included in Ester vinyl resin, mounted in the Teflon Furnace, transversally sectioned at the cervical, middle and apical thirds, which were subsequently photographed using a digital camera Cyber Shot DSC-TX10,attached to an operating microscope 3101XY DFVasconcelos with 40× magnification in order to measure the anatomical transversal area of the root canal, using the software AutoCAD 2008, comparing pre and post-instrumentation. All samples assembled in the Furnace also were submitted to x-ray in a standardized way to enable the comparison of the angle of Schneider pre-and post-instrumentation. Once collected the data, they were compared statistically using the program BioEstat 5.0. RESULT: The analysis of the results showed that in the cervical third, rotary systems were more effective than Endo-Eze TiLOS System with statistically significant differences (p ≤ 0,05. Apical and middle third changes in anatomy were similar, but apically, the ProTaper system caused more deviations when comparing the angle of Schneider,and areas before and after instrumentation(p ≤ 0,05. CONCLUSION: It was concluded that all the systems caused alteration in the original anatomy of the root canal when parameters as angle of Schneider and areas before and after preparation were used.

  8. Diagnosis and root canal treatment in a mandibular premolar with three canals.

    Science.gov (United States)

    Soares, Lanuce Rosa; Arruda, Marcos; de Arruda, Marcos Pôrto; Rangel, Andréa Leão; Takano, Edson; de Carvalho Júnior, Jacy Ribeiro; Saquy, Paulo Cesar

    2009-01-01

    This paper presents a case report of a left mandibular second premolar with three canals and three different apical foramina. A 39-year-old male patient presented to our clinic with pain in the mandibular left second premolar. Initially, pain was caused by cold stimulus and later was spontaneously. The intraoral clinical examination revealed a fractured amalgam restoration with occlusal caries. Percussion and cold (Endo-Frost) tests were positive. The radiographic examination showed the presence of two roots. The probable diagnosis was an acute pulpitis. After access cavity, it was observed remaining roof of the pulp chamber and mild bleeding in the tooth lingual area, indicating the possible presence of a third canal. The endodontic treatment was completed in a single session using Root ZX apex locator and K3 NiTi rotary system with surgical diameter corresponding to a .02/45 file in the three canals and irrigation with 1% sodium hypochlorite. The canals were obtured with gutta-percha cones and Sealer 26 using the lateral condensation technique. After 1 year of follow-up, the tooth was asymptomatic and periapical repair was observed radiographically. Internal alterations should be considered during the endodontic treatment of mandibular second premolars. The correct diagnosis of these alterations by the analysis of preoperative radiographs can help the location of two or more canals, thereby avoiding root therapy failure.

  9. Considerations concerning the Possibility of Contamination in the area of the Poarta Albă – Midia – Năvodari Canal

    OpenAIRE

    DINU, Irina

    2009-01-01

    Abstract. Pollution of the Danube – Black Sea and Poarta Albă – Midia – Năvodari canals is possible due to various sources, such as wastewater from different industrial units, sewage water discharged directly in the canals or along the tributary valleys, navigation, pipelines for the transport of petroleum products. Groundwater flow modeling has provided a useful tool for the simulation of pollution events scenarios, in order to estimate their consequences on the canal water and drinking wate...

  10. Laser dentistry: A new application of excimer laser in root canal therapy

    International Nuclear Information System (INIS)

    Pini, R.; Salimbeni, R.; Vannini, M.; Barone, R.; Clauser, C.

    1989-01-01

    We report the first study of the application of excimer lasers in dentistry for the treatment of dental root canals. High-energy ultraviolet (UV) radiation emitted by an XeCl excimer laser (308 nm) and delivered through suitable optical fibers can be used to remove residual organic tissue from the canals. To this aim, UV ablation thresholds of dental tissues have been measured, showing a preferential etching of infiltrated dentin in respect to healthy dentin, at laser fluences of 0.5-1.5 J/cm 2 . This technique has been tested on extracted tooth samples, simulating a clinical procedure. Fibers of decreasing core diameters have been used to treat different sections of the root canal down to its apical portion, resulting in an effective, easy, and fast cleaning action. Possible advantages of excimer laser clinical applications in respect to usual procedures are also discussed

  11. Hydrocele of the canal of Nuck

    Directory of Open Access Journals (Sweden)

    Nourah ALSaleh

    2018-02-01

    Full Text Available Hydrocele of the canal of Nuck is a rare condition in female children caused by a failure of complete obliteration of the canal of Nuck. The canal of Nuck is an abnormal patent pouch of the peritoneum extending anterior to the round ligament of the uterus into the labia majora. Incomplete obliteration of this canal (patent processus vaginalis can result in either an inguinal hernia or a hydrocele. Here, we report two cases of hydrocele of the canal of Nuck presented within a two-month period. In the first case, incarcerated right-sided inguinal hernia was suspected while the second case was clinically diagnosed as encysted hydrocele of canal of Nuck. Both patients underwent surgical exploration. Hydrocelectomy with high ligation was also performed. One month after the surgery, the first patient showed signs of hydrocele on contralateral side, while the other patient showed no sign of contralateral hydrocele or hernia.

  12. Assessment of three root canal preparation techniques on root canal geometry using micro-computed tomography: In vitro study

    Directory of Open Access Journals (Sweden)

    Shaikha M Al-Ali

    2012-01-01

    Full Text Available Aim: To assess the effects of three root canal preparation techniques on canal volume and surface area using three-dimensionally reconstructed root canals in extracted human maxillary molars. Materials and Methods: Thirty extracted Human Maxillary Molars having three separate roots and similar root shape were randomly selected from a pool of extracted teeth for this study and stored in normal saline solution until used. A computed tomography scanner (Philips Brilliance CT 64-slice was used to analyze root canals in extracted maxillary molars. Specimens were scanned before and after canals were prepared using stainless steel K-Files, Ni-Ti rotary ProTaper and rotary SafeSiders instruments. Differences in dentin volume removed, the surface area, the proportion of unchanged area and canal transportation were calculated using specially developed software. Results: Instrumentation of canals increased volume and surface area. Statistical analysis found a statistically significant difference among the 3 groups in total change in volume (P = 0.001 and total change in surface area (P = 0.13. Significant differences were found when testing both groups with group III (SafeSiders. Significant differences in change of volume were noted when grouping was made with respect to canal type (in MB and DB (P < 0.05. Conclusion: The current study used computed tomography, an innovative and non destructive technique, to illustrate changes in canal geometry. Overall, there were few statistically significant differences between the three instrumentation techniques used. SafeSiders stainless steel 40/0.02 instruments exhibit a greater cutting efficiency on dentin than K-Files and ProTaper. CT is a new and valuable tool to study root canal geometry and changes after preparation in great details. Further studies with 3D-techniques are required to fully understand the biomechanical aspects of root canal preparation.

  13. MODELING AND SIMULATION OF CYCLOID CURVES WITH APPLICATION IN ROBOTICS

    Directory of Open Access Journals (Sweden)

    Lucia PASCALE

    2010-10-01

    Full Text Available Mechanical power transmission by reducing the rotating speed under a constant transmission ratio represents the function of a large group of products known as speed reducers. Cycloid gearing roller (invented by L. Braren, through its qualities, has an important role in modern mechanical transmissions. The difference between numbers of teeth of the cycloid gear roller can be equal to 1 (| Z1 - Z2 |  1, without risk of interference, as a result, can be obtained big gear ratios in accordance with in lower overall dimensions.Thus, this paper presents the modeling and simulation of cycloid curves (epicycloids, respectively hypocycloid, which generates the cycloid gears used a lot in robotics.

  14. 21 CFR 872.3810 - Root canal post.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Root canal post. 872.3810 Section 872.3810 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3810 Root canal post. (a) Identification. A root canal... of the platinum group intended to be cemented into the root canal of a tooth to stabilize and support...

  15. IGBT Switching Characteristic Curve Embedded Half-Bridge MMC Modelling and Real Time Simulation Realization

    Science.gov (United States)

    Zhengang, Lu; Hongyang, Yu; Xi, Yang

    2017-05-01

    The Modular Multilevel Converter (MMC) is one of the most attractive topologies in recent years for medium or high voltage industrial applications, such as high voltage dc transmission (HVDC) and medium voltage varying speed motor drive. The wide adoption of MMCs in industry is mainly due to its flexible expandability, transformer-less configuration, common dc bus, high reliability from redundancy, and so on. But, when the sub module number of MMC is more, the test of MMC controller will cost more time and effort. Hardware in the loop test based on real time simulator will save a lot of time and money caused by the MMC test. And due to the flexible of HIL, it becomes more and more popular in the industry area. The MMC modelling method remains an important issue for the MMC HIL test. Specifically, the VSC model should realistically reflect the nonlinear device switching characteristics, switching and conduction losses, tailing current, and diode reverse recovery behaviour of a realistic converter. In this paper, an IGBT switching characteristic curve embedded half-bridge MMC modelling method is proposed. This method is based on the switching curve referring and sample circuit calculation, and it is sample for implementation. Based on the proposed method, a FPGA real time simulation is carried out with 200ns sample time. The real time simulation results show the proposed method is correct.

  16. Root Canal Stripping: Malpractice or Common Procedural Accident-An Ethical Dilemma in Endodontics.

    Science.gov (United States)

    Ciobanu, Ionela Elisabeta; Rusu, Darian; Stratul, Stefan-Ioan; Didilescu, Andreea Cristina; Cristache, Corina Marilena

    2016-01-01

    Root canal stripping is defined as an oblong, vertical perforation that appears especially in the middle section of curved root canals during endodontic treatments with nickel-titanium (Ni-Ti) instruments. Its occurrence may drastically affect the outcome of the treatment, transforming a common otherwise efficient endodontic procedure into a complication such as tooth extraction. In order to discuss the ethical and legal consequences, two cases of dental strip perforations are herewith presented. Due to the existence of risk factors for dental strip perforation, experience of the clinician and the use of magnification and modern imagistic methods (CBCT) may avoid or reduce the frequency of this type of accidents. Under correct working circumstances, dental stripping should not be regarded as a malpractice but as a procedural accident. However, the patient must always be informed, before and during the endodontic procedure, about the event and the possible complications that may occur.

  17. Revisión del estado del arte deIR-Ultra-Wideband y simulación de la respuesta impulsiva del canal IEEE802.15.4a Review of the state of art of IR-Ultra-Wideband and simulation of Impulse Responce of the IEEE 802.15.4a channel

    Directory of Open Access Journals (Sweden)

    Julio Suárez Páez

    2010-06-01

    Full Text Available Este artículo realiza una revisión del estado del arte de la tecnología basada en canales de Banda Ultra Ancha (UWB, Ultra–Wideband enfocándose en su regulación, estandarización, aplicaciones básicas, modelo de canal IEEE 802.15.4a y simulación de la respuesta impulsiva de este tipo de canal. También se pretende introducir al lector en las tecnologías basadas en canales IR–UWB y en los parámetros para el modelamiento y simulación del canal UWB IEEE 802.15.4a.This paper reviews the state of the art of the technology based in channels of Ultra Wide band (UWB Ultra–Wideband focusing on its regulation, standardization, basic applications, IEEE 802.15.4a channel model and simulation of the impulsive response of this type of channel. Also, it aims to introduce the reader to the technologies based on IR–UWB channels and the parameters for modeling and simulation of IEEE 802.15.4a UWB channel.

  18. Semiconductor laser irradiation improves root canal sealing during routine root canal therapy

    Science.gov (United States)

    Hu, Xingxue; Wang, Dashan; Cui, Ting; Yao, Ruyong

    2017-01-01

    Objective To evaluate the effect of semiconductor laser irradiation on root canal sealing after routine root canal therapy (RCT). Methods Sixty freshly extracted single-rooted human teeth were randomly divided into six groups (n = 10). The anatomic crowns were sectioned at the cementoenamel junction and the remaining roots were prepared endodontically with conventional RCT methods. Groups A and B were irradiated with semiconductor laser at 1W for 20 seconds; Groups C and D were ultrasonically rinsed for 60 seconds as positive control groups; Groups E and F without treatment of root canal prior to RCT as negative control groups. Root canal sealing of Groups A, C and E were evaluated by measurements of apical microleakage. The teeth from Groups B, D and F were sectioned, and the micro-structures were examined with scanning electron microscopy (SEM). One way ANOVA and LSD-t test were used for statistical analysis (α = .05). Results The apical sealing of both the laser irradiated group and the ultrasonic irrigated group were significantly different from the control group (pirrigated group (p>0.5). SEM observation showed that most of the dentinal tubules in the laser irradiation group melted, narrowed or closed, while most of the dentinal tubules in the ultrasonic irrigation group were filled with tooth paste. Conclusion The application of semiconductor laser prior to root canal obturation increases the apical sealing of the roots treated. PMID:28957407

  19. Glide path preparation in S-shaped canals with rotary pathfinding nickel-titanium instruments.

    Science.gov (United States)

    Ajuz, Natasha C C; Armada, Luciana; Gonçalves, Lucio S; Debelian, Gilberto; Siqueira, José F

    2013-04-01

    This study compared the incidence of deviation along S-shaped (double-curved) canals after glide path preparation with 2 nickel-titanium (NiTi) rotary pathfinding instruments and hand K-files. S-shaped canals from 60 training blocks were filled with ink, and preinstrumentation images were obtained by using a stereomicroscope. Glide path preparation was performed by an endodontist who used hand stainless steel K-files (up to size 20), rotary NiTi PathFile instruments (up to size 19), or rotary NiTi Scout RaCe instruments (up to size 20). Postinstrumentation images were taken by using exactly the same conditions as for the preinstrumentation images, and both pictures were superimposed. Differences along the S-shaped canal for the mesial and distal aspects were measured to evaluate the occurrence of deviation. Intragroup analysis showed that all instruments promoted some deviation in virtually all levels. Overall, regardless of the group, deviations were observed in the mesial wall at the canal terminus and at levels 4, 5, 6 and 7 mm and in the distal wall at levels 1, 2, and 3 mm. These levels corresponded to the inner walls of each curvature. Both rotary NiTi instruments performed significantly better than hand K-files at all levels (P instruments showed significantly better results than PathFiles at levels 0, 2, 3, 5, and 6 mm (P rotary NiTi instruments are suitable for adequate glide path preparation because they promoted less deviation from the original canal anatomy when compared with hand-operated instruments. Of the 2 rotary pathfinding instruments, Scout RaCe showed an overall significantly better performance. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  20. The shape of the human lumbar vertebral canal A forma do canal vertebral lombar humano

    Directory of Open Access Journals (Sweden)

    Edmundo Zarzur

    1996-09-01

    Full Text Available Literature on the anatomy of the human vertebral column characterizes the shape of the lumbar vertebral canal as triangular. The purpose of the present study was to determine the precise shape of the lumbar vertebral canal. Ten lumbar vertebral columns of adult male cadavers were dissected. Two transverse sections were performed in the third lumbar vertebra. One section was performed at the level of the lower border of the ligamenta flava, and the other section was performed at the level of the pedicles. The shape of the lumbar vertebral canal at the level of the pedicles tends to be oval or circular, whereas the shape of the lumbar vertebral canal at the level of the lower border of the ligamenta flava is triangular. Thus, the shape of the human lumbar vertebral canal is not exclusively triangular, as reported in the literature. It is related to the level of the transversal section performed on the lumbar vertebra. This finding should be taken into consideration among factors involved in the spread of solutions introduced into the epidural space.A literatura sobre a anatomia da coluna vertebral descreve como sendo triangular o formato do canal vertebral na região lombar. O objetivo deste estudo é determinar a real forma do canal da coluna vertebral lombar.Dez colunas vertebrais de cadáveres de homens adultos foram dissecadas. Dois cortes transversais foram executados na terceira vértebra lombar. Um corte foi feito no nível das bordas inferiores de dois ligamentos amarelos vizinhos e o outro corte foi transversal, no nível dos pedículos. A forma do canal vertebral variou: no nível dos pedículos ela tende a ser oval ou circular e junto às bordas inferiores dos ligamentos amarelos passa a ser triangular. Portanto, a forma do canal vertebral lombar não é somente triangular; ela depende do nível em que se faz o corte transversal da vértebra. Estes achados devem ser levados em consideração entre os fatores envolvidos na difusão das

  1. Atomistic simulation of the premelting of iron and aluminum : Implications for high-pressure melting-curve measurements

    NARCIS (Netherlands)

    Starikov, Sergey V.; Stegailov, Vladimir V.

    2009-01-01

    Using atomistic simulations we show the importance of the surface premelting phenomenon for the melting-curve measurements at high pressures. The model under consideration mimics the experimental conditions deployed for melting studies with diamond-anvil cells. The iron is considered in this work

  2. Shaping ability of two M-wire and two traditional nickel-titanium instrumentation systems in S-shaped resin canals.

    Science.gov (United States)

    Ceyhanli, K T; Kamaci, A; Taner, M; Erdilek, N; Celik, D

    2015-01-01

    The aim of this study was to evaluate the shaping effects of two M-wire and two traditional nickel-titanium (NiTi) rotary systems in simulated S-shaped resin canals. Forty simulated S-shaped canals in resin blocks were instrumented with two traditional (ProTaper, Sendoline S5) and two M-wire (WaveOne, GT series X) NiTi systems according to the manufacturers' instructions. Ten resin blocks were used for each system. Pre- and post-instrumentation images were captured using a stereomicroscope and superimposed with an image program. Canal transportation, material removal, and aberrations were evaluated and recorded as numeric parameters. Data were analyzed using one-way ANOVA and post-hoc Tukey tests with a 95% confidence interval. There were significant differences between systems in terms of transportation and material removal (Pwire or traditional NiTi) and kinematics (rotary or reciprocating motion) did not affect the shaping abilities of the systems. The extended file designs of highly tapered NiTi systems (ProTaper, WaveOne) resulted in greater deviations from the original root canal trace and more material removal when compared to less tapered systems (Sendoline S5, GT series X).

  3. Multivariate analysis of the cleaning efficacy of different final irrigation techniques in the canal and isthmus of mandibular posterior teeth

    Directory of Open Access Journals (Sweden)

    Yeon-Jee Yoo

    2013-08-01

    Full Text Available Objectives The aim of this study was to compare the cleaning efficacy of different final irrigation regimens in canal and isthmus of mandibular molars, and to evaluate the influence of related variables on cleaning efficacy of the irrigation systems. Materials and Methods Mesial root canals from 60 mandibular molars were prepared and divided into 4 experimental groups according to the final irrigation technique: Group C, syringe irrigation; Group U, ultrasonics activation; Group SC, VPro StreamClean irrigation; Group EV, EndoVac irrigation. Cross-sections at 1, 3 and 5 mm levels from the apex were examined to calculate remaining debris area in the canal and isthmus spaces. Statistical analysis was completed by using Kruskal-Wallis test and Mann-Whitney U test for comparison among groups, and multivariate linear analysis to identify the significant variables (regular replenishment of irrigant, vapor lock management, and ultrasonic activation of irrigant affecting the cleaning efficacy of the experimental groups. Results Group SC and EV showed significantly higher canal cleanliness values than group C and U at 1 mm level (p < 0.05, and higher isthmus cleanliness values than group U at 3 mm and all levels of group C (p < 0.05. Multivariate linear regression analysis demonstrated that all variables had independent positive correlation at 1 mm level of canal and at all levels of isthmus with statistical significances. Conclusions Both VPro StreamClean and EndoVac system showed favorable result as final irrigation regimens for cleaning debris in the complicated root canal system having curved canal and/or isthmus. The debridement of the isthmi significantly depends on the variables rather than the canals.

  4. Dorello's Canal for Laymen: A Lego-Like Presentation.

    Science.gov (United States)

    Ezer, Haim; Banerjee, Anirban Deep; Thakur, Jai Deep; Nanda, Anil

    2012-06-01

    Objective Dorello's canal was first described by Gruber in 1859, and later by Dorello. Vail also described the anatomy of Dorello's canal. In the preceding century, Dorello's canal was clinically important, in understanding sixth nerve palsy and nowadays it is mostly important for skull base surgery. The understanding of the three dimensional anatomy, of this canal is very difficult to understand, and there is no simple explanation for its anatomy and its relationship with adjacent structures. We present a simple, Lego-like, presentation of Dorello's canal, in a stepwise manner. Materials and Methods Dorello's canal was dissected in five formalin-fixed cadaver specimens (10 sides). The craniotomy was performed, while preserving the neural and vascular structures associated with the canal. A 3D model was created, to explain the canal's anatomy. Results Using the petrous pyramid, the sixth nerve, the cavernous sinus, the trigeminal ganglion, the petorclival ligament and the posterior clinoid, the three-dimensional structure of Dorello's canal was defined. This simple representation aids in understanding the three dimensional relationship of Dorello's canal to its neighboring structures. Conclusion Dorello's canal with its three dimensional structure and relationship to its neighboring anatomical structures could be reconstructed using a few anatomical building blocks. This method simplifies the understanding of this complex anatomical structure, and could be used for teaching purposes for aspiring neurosurgeons, and anatomy students.

  5. Effective analysis of the use of peracetic acid after instrumentation of root canals contaminated with Enterococcus faecalis.

    Science.gov (United States)

    Cord, Caroline Berwanger; Velasco, Rafael Vidal Cortez; Ribeiro Melo Lima, Laíla Fernanda; Rocha, Daniel Guimarães Pedro; da Silveira Bueno, Carlos Eduardo; Pinheiro, Sérgio Luiz

    2014-08-01

    The aim of this study was to evaluate the effectiveness of peracetic acid (PAA) in cleaning root canals contaminated with Enterococcus faecalis. Sixty first and second mandibular molars were used. Their mesiobuccal canals were prepared with the Reciproc System (VDW, Munich, Germany). The canals were irrigated with 10 mL saline during instrumentation. The teeth were randomly divided into 3 groups (n = 20), according to the irrigation solution to be used after instrumentation: group PAA (5 mL 1% PAA), group EDTA/sodium hypochlorite (NaOCl) (5 mL 17% EDTA followed by 5 mL 2.5% sodium hypochlorite), and group S (5 mL saline). Microbiological samples were collected before instrumentation and after final irrigation. Bacterial quantification was performed by counting the number of colony-forming units (CFUs/mL). The results were analyzed by the nonparametric Wilcoxon and Kruskal-Wallis tests. The 3 groups showed a significant reduction (P  .05). According to the results of the present study, the effectiveness of 1% PAA was similar to that of 17% EDTA + 2.5% NaOCl in cleaning curved root canals contaminated with E. faecalis. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  6. MR evaluation of cervical CSF flow. An examination in patients with spinal canal stenosis

    Energy Technology Data Exchange (ETDEWEB)

    Iida, Makoto [Miyoshi General Hospital, Hiroshima (Japan); Kajima, Toshio; Miyasaka, Kenji; Nakanishi, Tadashi; Ono, Chiaki; Ito, Katsuhide

    1999-06-01

    To evaluate the flow dynamics of cerebrospinal fluid (CSF) throughout the cervical spine, 18 healthy controls and 14 patients with spinal canal stenosis were examined by phase-contrast cine MR. MR imaging was performed using a sagittal technique that is flow-sensitive in the craniocaudal direction. Flow encoding depicted craniocaudal flow as high intensity and caudocranial flow as low intensity. In this technique, either retrospective cardiac or peripheral gating was used to cover the complete cardiac cycle. This pulse sequence yielded 16 quantitative flow-encoded images per cardiac cycle. Using a region-of-interest cursor at each vertebral level, the graphs of flow-velocity versus time were generated. The recorded CSF at each vertebral level in the controls showed almost the same pattern in the change of flow in the craniocaudal direction, indicating that the onset of craniocaudal CSF flow was synchronous with the onset of cardiac systole in these subjects. At all vertebral levels, flow-velocity time curves showed the same variation in pattern. CSF flow was significantly lower in patients than in controls at each vertebral level (p<0.01). In addition, the flow patterns of the patients with spinal canal stenosis differed at each vertebral level. As a results, the total sum of the difference in velocity between graphs of two serial vertebrae at all sampling points (the area between the curves: ABC) per mean velocity amplitude in the patients was significantly higher than controls (p<0.05). Furthermore, the ABC per mean velocity amplitude at the stenotic level was significantly larger in the patients than that at the non-stenotic level (p<0.01). These data suggest that turbulent CSF flow occurs at the stenotic level. Thus, assessment of CSF flow dynamics is a useful adjunct to routine MRI in patients with spinal canal stenosis. (author)

  7. Influence of Cone-Beam Computed Tomography filters on diagnosis of simulated endodontic complications.

    Science.gov (United States)

    Verner, F S; D'Addazio, P S; Campos, C N; Devito, K L; Almeida, S M; Junqueira, R B

    2017-11-01

    To evaluate the influence of cone-beam computed tomography (CBCT) filters on diagnosis of simulated endodontic complications. Sixteen human teeth, in three mandibles, were submitted to the following simulated endodontic complications: (G1) fractured file, (G2) perforations in the canal walls, (G3) deviated cast post, and (G4) external root resorption. The mandibles were submitted to CBCT examination (I-Cat ® Next Generation). Five oral radiologists evaluated the images independently with and without XoranCat ® software filters. Accuracy, sensitivity and specificity were determined. ROC curves were calculated for each group with the filters, and the areas under the curves were compared using anova (one-way) test. McNemar test was applied for pair-wise agreement between all images versus the gold standard and original images versus images with filters (P originals images (P = 0.00 for all filters) only in G1 group. There were no differences in the other groups. The filters did not improve the diagnosis of the simulated endodontic complications evaluated. Their diagnosis remains a major challenge in clinical practice. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  8. Microbiological examination of infected dental root canals.

    Science.gov (United States)

    Gomes, B P F A; Pinheiro, E T; Gadê-Neto, C R; Sousa, E L R; Ferraz, C C R; Zaia, A A; Teixeira, F B; Souza-Filho, F J

    2004-04-01

    The aim of this study was to investigate the root canal microbiota of primary and secondary root-infected canals and the association of constituent species with specific endodontic signs and symptoms. Microbial samples were taken from 60 root canals, 41 with necrotic pulp tissues (primary infection) and 19 with failed endodontic treatment (secondary infection). Strict anaerobic techniques were used for serial dilution, plating, incubation and identification. A total of 224 cultivable isolates were recovered belonging to 56 different bacterial species. Individual root canals yielded a maximum of 10 bacterial species. Of the bacterial isolates, 70% were either strict anaerobes or microphilic. The anaerobes most frequently isolated were: Peptostreptococcus micros (35%), Fusobacterium necrophorum (23.3%), Fusobacterium nucleatum (11.7%), Prevotella intermedia/nigrescens (16.7%), Porphyromonas gingivalis (6.7%) and Porphyromonas endodontalis (5%). The root canal microflora of untreated teeth with apical periodontitis was found to be mixed, comprising gram-negative and gram-positive and mostly anaerobic microorganisms and usually containing more than 3 species per canal. On the other hand, facultative anaerobic and gram-positive bacteria predominated in canals with failed endodontic treatment, which harbored 1-2 species per canal. Suggested relationships were found between anaerobes, especially gram-negatives, and the presence or history of pain, tenderness to percussion and swelling (PEubacterium spp. (both Pspp. (Pspp. (Pspp. (Pspp. (Pspp. (Pspp. (Pspp. (Pspp., P. micros, F. necrophorum (P<0.05). Our findings indicate potential complex interactions of species resulting in characteristic clinical pictures which cannot be achieved by individual species alone. They also indicate that the microbiota of primary infected canals with apical periodontitis differs in number and in species from the secondary infected canals by using the culture technique.

  9. External dose conversion factor from canal water

    International Nuclear Information System (INIS)

    Bhargava, Pradeep; Chitra, S.; Mhatre, Arti S.; Singh, Kapil Deo

    2016-01-01

    External dose needs to be estimated for the radioactivity discharged into the canal, as it constitutes one of the pathways of exposure to the public. Two activities are considered here: i) a walk along the bank of the canal ii) and the walk on the bridge. A concentration of 1 Bq/l is assumed here for the gross beta activity for the estimation of the dose conversion factor. A canal of width 14.39 m and the depth of 2.5 m is considered for this study. Length of the canal is taken to be infinite. Canal side wall is assumed to be the 25 cm thick concrete. Two points are selected, one on the bank, and the second on a bridge 1 m above the top surface of canal water. Dose Conversion factors for the person moving on the Bridge (at one meter above the water surface) and standing on bank of canal is estimated by using the QAD CG code for 137 Cs. Dose conversion factors for the location mentioned above are found to be 1.11E-10 Sv/hr/(Bq/l) and 1.55 E-11 Sv/hr/(Bq/l) for bridge and bank of canal respectively. (author)

  10. Clinical significance of dental root canal microflora.

    Science.gov (United States)

    Gomes, B P; Lilley, J D; Drucker, D B

    1996-01-01

    Previous work by this group has shown that a significant association exists between pain and the presence of either Prevotella or Peptostreptococcus spp. in dental root canals. The aim of this study was to examine a more extensive series of canals microbiologically, to determine whether any other particular endodontic symptoms or clinical signs showed specific associations with individual bacterial species. Seventy root canals were examined microbiologically and clinical data collected to investigate in detail such associations. Of the canals studied, 37 were associated with pain, 49 with tenderness to percussion, 23 with swelling, six with purulent exudate and 57 presented with wet root canals. Anaerobes were isolated from 70.3% of painful canals and from 29.7% of pain-free canals. Significant associations were found between (a) pain and either Prevotella spp. or peptostreptococci, both with P spp. (P Eubacterium spp. (P spp. or Pstr. micros, both with P spp. (each P Eubacterium, Peptostreptococcus, Prevotella or Propionibacterium (each P < 0.05). It was concluded that several different endodontic clinical signs and symptoms are significantly associated with specific bacterial species.

  11. El Canal del Atazar I

    Directory of Open Access Journals (Sweden)

    López de Berges y de los Santos, Emilio

    1967-03-01

    Full Text Available The Atazar Canal helps to supply Madrid with water, from the rivers Lozoya, Jarama and Sorbe. The section which operates at present starts at the Torrelaguna dam and finishes at the El Goloso reservoir. Later a further section will be added, from the Atazar dam, on the Lozoya river, to link up with the control dam at Torrelaguna. The canal capacity is 16 m3/sec, and it is 43.47 km long. It has a slope of 4/10.000. The cross section is similar to that of the Jarama canal, already built. There are interconnections between this canal and the Canal Alto, which previously supplied the high and medium part of Madrid. To overcome the ground unevenness 5 syphons have been built, the most important of which is the Colmenar Goloso syphon, which is 10.88 km in length. Construction commenced on December 10, 1962, and water reached Madrid on June 15th, 1966. The initial budget for this project was 1,500 million pesetas.El canal del Atazar refuerza considerablemente el abastecimiento de aguas a Madrid, procedentes de los ríos Lozoya, Jarama y, en un próximo futuro, del Sorbe. El tramo, actualmente en funcionamiento, empieza en el salto de Torrelaguna y finaliza en los depósitos de El Goloso. Más adelante se completará su trazado mediante un nuevo tramo que partirá del embalse de Atazar, en el Lozoya, para unirse al actual en el depósito regulador de Torrelaguna. Su capacidad es de 16 m3/s; su longitud, 43,471 km, y su pendiente, 4 diezmilésimas. La sección tipo es análoga a la del canal del Jarama, de construcción anterior. Mediante la oportuna obra de transvase se realizan intercambios entre este Canal y el Canal Alto que abastecía anteriormente la parte media y alta de la capital. Para salvar los desniveles del terreno se han construido 5 sifones, siendo el más importante el de Colmenar-Goloso, con una longitud de 10,8S4 km. El comienzo de las obras tuvo lugar el 10 de diciembre de 1962, y el agua llegó a Madrid el 15 de junio de 1966. Su

  12. Detection of Mesiobuccal Canal in Maxillary Molars and Distolingual Canal in Mandibular Molars by Dental CT: A Retrospective Study of 100 Cases

    Directory of Open Access Journals (Sweden)

    Sushma Rathi

    2010-01-01

    Full Text Available Objective. To detect presence of MB2 canal in maxillary molars and distolingual canal in mandibular molars by Dental CT. Material and Methods. A retrospective study of 100 Dental CTs was done. Axial and paraxial images obtained were used to assess the presence of MB2 canal in maxillary molars and distolingual canal in mandibular molars. Results. The youngest patient was of 11 years while the eldest patient was of 77 years. Males were 58 in number and females were 42 in number. MB2 canals were present in 57 patients and distolingual canal was present in 18 patients. Maximum MB2 canals were present in age group between 51 and 60 years, while distolingual canals were present in age group of 21–30 years. Conclusion. Dental CT allows adequate visualization of variation in root canal morphology and can be important diagnostic tool for successful endodontic therapy.

  13. Molecular dynamics simulations of the melting curve of NiAl alloy under pressure

    OpenAIRE

    Wenjin Zhang; Yufeng Peng; Zhongli Liu

    2014-01-01

    The melting curve of B2-NiAl alloy under pressure has been investigated using molecular dynamics technique and the embedded atom method (EAM) potential. The melting temperatures were determined with two approaches, the one-phase and the two-phase methods. The first one simulates a homogeneous melting, while the second one involves a heterogeneous melting of materials. Both approaches reduce the superheating effectively and their results are close to each other at the applied pressures. By fit...

  14. 77 FR 42644 - Safety Zone; Canal Fest of the Tonawandas, Erie Canal, Tonawanda, NY

    Science.gov (United States)

    2012-07-20

    .... ACTION: Temporary final rule. SUMMARY: The Coast Guard is establishing a temporary safety zone on the... Canal during the Canal Fest of the Tonawandas Fireworks display. This temporary safety zone is necessary to protect spectators and vessels from the hazards associated with a fireworks display. DATES: This...

  15. Water Environment Evolution along the China Grand Canal

    International Nuclear Information System (INIS)

    Mao, F; Wu, Y X; Yang, B F; Li, X J

    2014-01-01

    The China Grand Canal is one of the earliest canals in the world, having lasted for nearly 3000 years. Even its section canals have a rich history, such as the North-South Grand Canal that was established during the Sui Dynasty, whereas the Beijing-Hangzhou Canal was excavated during the Yuan Dynasty and the east line of the South-to-North Water Diversion. As one of the longest in the world, the China Grand Canal's total length is over 3500 kilometers. This length includes the navigable, unnavigable, and underground sections. Making the best use of situations and according to local conditions, the Chinese people harmoniously constructed the Beijing-Hangzhou Canal with nature. Tens of millions of workers took nearly 3000 years to complete the great shipping system. Navigable sections still exist for up to 900 kilometers and the volume of freight traffic is approximately 300 million tons. The canal remains the main logistical channel of the North-to-South Coal Transportation, South-to-North Water Diversion, and resources circulation. To date, China is promoting the success of heritage application. Part of these efforts is the declaration of the China Grand Canal as a World Cultural Heritage by 2014. In addition, the east route of the South-to-North Water Transfer project is planned to be navigable by 2016. The ancient Beijing-Hangzhou Grand Canal will usher in the new ecological civilization and cultural revival along the canal. This paper presents technical methods of water environment evolution research on the river system, river, and water quality along the Beijing-Hangzhou Canal through the integration of historical literature and modern remote sensing image data. The study carried out water environment investigation and analysis along the Beijing-Hangzhou canal by using ETM, SPOT image data, and GPS measurement data. Spatial and temporal evolution characteristics and regulations of the Beijing-Hangzhou Grand Canal regional water environment in the span of

  16. Computed tomography of the facial canal

    International Nuclear Information System (INIS)

    Kiuchi, Sousuke

    1983-01-01

    The radiological details of the facial canal was investigated by computed tomography. In the first part of this study, dry skulls were used to delineate the full course of the facial canal by computed tomography. In the second part of this study, the patients with chronic otitis media and secondary cholesteatoma were evaluated. The labyrinthine and tympanic parts of the canal were well demonstrated with the axial scanning, and the mastoid part with the coronal scanning. Moreover, computed tomography showed excellent delineation of the middle ear contents. In patients with secondary cholesteatoma, the destructions of the intratympanic course of the bony facial canal were also assessed preoperatively. (author)

  17. Radiation-induced external ear canal cholesteatoma-like disease

    Energy Technology Data Exchange (ETDEWEB)

    Ishihara, Akiko; Okuno, Hideji; Noguchi, Keisuke; Komatsuzaki, Atsushi [Tokyo Medical and Dental Univ. (Japan). School of Medicine

    1999-06-01

    Three cases of cholesteatoma-like disease in the ear canals after radiation therapy for head and neck tumor were reported. Effect of irradiation on bone and soft tissue including skin brings about pathological reaction to the external ear canal as well. Two types of disease resembling cholesteatomas have been recognized: keratosis obturans (KO) and external auditory canal cholesteatoma (EACC). KO appears to be derived from disease of canal skin involved with keratinization, creating a widning of the canal. EACC, on the other hand, seems to develop in the disease of bony canal where a localized absorption of its bone with invasion of squamous epithelium takes place. (author)

  18. Signature Curves Statistics of DNA Supercoils

    OpenAIRE

    Shakiban, Cheri; Lloyd, Peter

    2004-01-01

    In this paper we describe the Euclidean signature curves for two dimensional closed curves in the plane and their generalization to closed space curves. The focus will be on discrete numerical methods for approximating such curves. Further we will apply these numerical methods to plot the signature curves related to three-dimensional simulated DNA supercoils. Our primary focus will be on statistical analysis of the data generated for the signature curves of the supercoils. We will try to esta...

  19. Effect of yield curves and porous crush on hydrocode simulations of asteroid airburst

    Science.gov (United States)

    Robertson, D. K.; Mathias, D. L.

    2017-03-01

    Simulations of asteroid airburst are being conducted to obtain best estimates of damage areas and assess sensitivity to variables for asteroid characterization and mitigation efforts. The simulations presented here employed the ALE3D hydrocode to examine the breakup and energy deposition of asteroids entering the Earth's atmosphere, using the Chelyabinsk meteor as a test case. This paper examines the effect of increasingly complex material models on the energy deposition profile. Modeling the meteor as a rock having a single strength can reproduce airburst altitude and energy deposition reasonably well but is not representative of real rock masses (large bodies of material). Accounting for a yield curve that includes different tensile, shear, and compressive strengths shows that shear strength determines the burst altitude. Including yield curves and compaction of porous spaces in the material changes the detailed mechanics of the breakup but only has a limited effect on the burst altitude and energy deposition. Strong asteroids fail and create peak energy deposition close to the altitude at which ram dynamic pressure equals the material strength. Weak asteroids, even though they structurally fail at high altitude, require the increased pressure at lower altitude to disrupt and disperse the rubble. As a result, a wide range of weaker asteroid strengths produce peak energy deposition at a similar altitude.

  20. An explanation for the shape of nanoindentation unloading curves based on finite element simulation

    International Nuclear Information System (INIS)

    Bolshakov, A.; Pharr, G.M.

    1995-01-01

    Current methods for measuring hardness and modulus from nanoindentation load-displacement data are based on Sneddon's equations for the indentation of an elastic half-space by an axially symmetric rigid punch. Recent experiments have shown that nanoindentation unloading data are distinctly curved in a manner which is not consistent with either the flat punch or the conical indenter geometries frequently used in modeling, but are more closely approximated by a parabola of revolution. Finite element simulations for conical indentation of an elastic-plastic material are presented which corroborate the experimental observations, and from which a simple explanation for the shape of the unloading curve is derived. The explanation is based on the concept of an effective indenter shape whose geometry is determined by the shape of the plastic hardness impression formed during indentation

  1. Acceleration induced water removal from ear canals.

    Science.gov (United States)

    Kang, Hosung; Averett, Katelee; Jung, Sunghwan

    2017-11-01

    Children and adults commonly experience having water trapped in the ear canals after swimming. To remove the water, individuals will shake their head sideways. Since a child's ear canal has a smaller diameter, it requires more acceleration of the head to remove the trapped water. In this study, we theoretically and experimentally investigated the acceleration required to break the surface meniscus of the water in artificial ear canals and hydrophobic-coated glass tubes. In experiments, ear canal models were 3D-printed from a CT-scanned human head. Also, glass tubes were coated with silane to match the hydrophobicity in ear canals. Then, using a linear stage, we measured the acceleration values required to forcefully eject the water from the artificial ear canals and glass tubes. A theoretical model was developed to predict the critical acceleration at a given tube diameter and water volume by using a modified Rayleigh-Taylor instability. Furthermore, this research can shed light on the potential of long-term brain injury and damage by shaking the head to push the water out of the ear canal. This research was supported by National Science Foundation Grant CBET-1604424.

  2. Hood Canal Steelhead - Hood Canal Steelhead Supplementation Experiment

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Hood Canal Steelhead Project is a 17-year before-after-control-impact experiment that tests the effects of supplementation on natural steelhead populations in...

  3. Molecular dynamics simulations of the melting curve of NiAl alloy under pressure

    International Nuclear Information System (INIS)

    Zhang, Wenjin; Peng, Yufeng; Liu, Zhongli

    2014-01-01

    The melting curve of B2-NiAl alloy under pressure has been investigated using molecular dynamics technique and the embedded atom method (EAM) potential. The melting temperatures were determined with two approaches, the one-phase and the two-phase methods. The first one simulates a homogeneous melting, while the second one involves a heterogeneous melting of materials. Both approaches reduce the superheating effectively and their results are close to each other at the applied pressures. By fitting the well-known Simon equation to our melting data, we yielded the melting curves for NiAl: 1783(1 + P/9.801) 0.298 (one-phase approach), 1850(1 + P/12.806) 0.357 (two-phase approach). The good agreement of the resulting equation of states and the zero-pressure melting point (calc., 1850 ± 25 K, exp., 1911 K) with experiment proved the correctness of these results. These melting data complemented the absence of experimental high-pressure melting of NiAl. To check the transferability of this EAM potential, we have also predicted the melting curves of pure nickel and pure aluminum. Results show the calculated melting point of Nickel agrees well with experiment at zero pressure, while the melting point of aluminum is slightly higher than experiment

  4. Effect of canal preparation with TRUShape and Vortex rotary instruments on three-dimensional geometry of oval root canals.

    Science.gov (United States)

    Arias, Ana; Paqué, Frank; Shyn, Stephanie; Murphy, Sarah; Peters, Ove A

    2018-04-01

    The purpose of this study was to assess the geometry of non-round root canals after preparation with TRUShape (a novel instrument with s-shaped longitudinal design) in comparison to conventional rotary instrumentation using micro-computed tomography. Twenty distal root canals of mandibular molars were randomly distributed in two groups to be shaped with either TRUShape or Vortex rotaries. Percentages of unprepared surface and volume of dentin removal for the entire canal and for the apical 4 mm were calculated. Canal transportation and the structure model index (SMI) were assessed. Data were compared with Student t-tests. Shaping with both techniques resulted in similar prepared surface and volume of dentin removed, as well as the extent of canal transportation. The SMI shape factor was significantly lower for TRUShape preparations (P = 0.04) suggesting less rounding during rotary preparation. Although both instruments were suitable for the preparation of oval canals, TRUShape appeared to better conform to the original ribbon-shaped anatomy. © 2017 Australian Society of Endodontology Inc.

  5. Radioanatomy of the singular nerve canal

    Energy Technology Data Exchange (ETDEWEB)

    Muren, C. [Dept. of Diagnostic Radiology, Sabbatsbergs Hospital, Stockholm (Sweden); Wadin, K. [University Hospital, Uppsala (Sweden); Dimopoulos, P. [University Hospital, Uppsala (Sweden)

    1991-08-01

    The singular canal conveys vestibular nerve fibers from the ampulla of the posterior semicircular canal to the posteroinferior border of the internal auditory meatus. Radiographic identification of this anatomic structure helps to distinguish it from a fracture. It is also a landmark in certain surgical procedures. Computed tomography (CT) examinations of deep-frozen temporal bone specimens were compared with subsequently prepared plastic casts of these bones, showing good correlation between the anatomy and the images. The singular canal and its variable anatomy were studied in CT examinations of 107 patients. The singular canal could be identified, in both the axial and in the coronal planes. Its point of entry into the internal auditory meatus varied considerably. (orig.)

  6. Cyclic fatigue resistance of R-Pilot, HyFlex EDM and PathFile nickel-titanium glide path files in artificial canals with double (S-shaped) curvature.

    Science.gov (United States)

    Uslu, G; Özyürek, T; Yılmaz, K; Gündoğar, M

    2018-05-01

    To examine the cyclic fatigue resistances of R-Pilot, HyFlex EDM and PathFile NiTi glide path files in S-shaped artificial canals. Twenty R-Pilot (12.5/.04), 20 HyFlex EDM (10/.05) and 20 PathFile (19/.02) single-file glide path files were included. Sixty files (n: 20/each) were subjected to static cyclic fatigue testing using double-curved canals until fracture occurred (TF). The number of cycles to fracture (NCF) was calculated by multiplying the rpm value by the TF. The length of the fractured fragment (FL) was determined by a digital microcaliper. Six samples of fractured files (n: 2/each) were examined by SEM to determine the fracture mode. The NCF and the FL data were analysed using one-way anova, post hoc Tamhane and Kruskal-Wallis tests using SPPS 21 software. The significance level was set at 5%. In the double-curved canal, all the files fractured first in the apical curvature and then in the coronal curvature. The NCF values revealed that the R-Pilot had the greatest cyclic fatigue resistance, followed by the HyFlex EDM and PathFile in both the apical and coronal curvatures (P < 0.05). R-Pilot NiTi glide path files, used in a reciprocating motion, had the greatest cyclic fatigue resistance amongst the tested NiTi glide path files in an artificial S-shaped canal. © 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  7. A comparative study for different shielding material composition and beam geometry applied to PET facilities: simulated transmission curves

    Energy Technology Data Exchange (ETDEWEB)

    Hoff, Gabriela [Pontificia Univ. Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil). Grupo de Experimentacao e Simulacao Computacional em Fisica Medica; Costa, Paulo Roberto, E-mail: pcosta@if.usp.br [Universidade de Sao Paulo (IF/USP), SP (Brazil). Dept. de Fisica Nuclear. Lab. de Dosimetria das Radiacoes e Fisica Medica

    2013-03-15

    The aim of this work is to simulate transmission data for different beam geometry and material composition in order to evaluate the effect of these parameters on transmission curves. The simulations are focused on outgoing spectra for shielding barriers used in PET facilities. The behavior of the transmission was evaluated as a function of the shielding material composition and thickness using Geant4 Monte Carlo code, version 9.2 p 03.The application was benchmarked for barited mortar and compared to The American Association of Physicists in Medicine (AAPM) data for lead. Their influence on the transmission curves as well the study of the influence of the shielding material composition and beam geometry on the outgoing spectra were performed. Characteristics of transmitted spectra, such as shape, average energy and Half-Value Layer (HVL), were also evaluated. The Geant4 toolkit benchmark for the energy resulting from the positron annihilation phenomena and its application in transmission curves description shown good agreement between data published by American Association on Physicists in Medicine task group 108 and experimental data published by Brazil. The transmission properties for different material compositions were also studied and have shown low dependency with the considered thicknesses. The broad and narrow beams configuration presented significant differences on the result. The fitting parameter for determining the transmission curves equations, according to Archer model is presented for different material. As conclusion were defined that beam geometry has significant influence and the composition has low influence on transmission curves for shielding design for the range of energy applied to PET. (author)

  8. A comparative study for different shielding material composition and beam geometry applied to PET facilities: simulated transmission curves

    International Nuclear Information System (INIS)

    Hoff, Gabriela; Costa, Paulo Roberto

    2013-01-01

    The aim of this work is to simulate transmission data for different beam geometry and material composition in order to evaluate the effect of these parameters on transmission curves. The simulations are focused on outgoing spectra for shielding barriers used in PET facilities. The behavior of the transmission was evaluated as a function of the shielding material composition and thickness using Geant4 Monte Carlo code, version 9.2 p 03.The application was benchmarked for barited mortar and compared to The American Association of Physicists in Medicine (AAPM) data for lead. Their influence on the transmission curves as well the study of the influence of the shielding material composition and beam geometry on the outgoing spectra were performed. Characteristics of transmitted spectra, such as shape, average energy and Half-Value Layer (HVL), were also evaluated. The Geant4 toolkit benchmark for the energy resulting from the positron annihilation phenomena and its application in transmission curves description shown good agreement between data published by American Association on Physicists in Medicine task group 108 and experimental data published by Brazil. The transmission properties for different material compositions were also studied and have shown low dependency with the considered thicknesses. The broad and narrow beams configuration presented significant differences on the result. The fitting parameter for determining the transmission curves equations, according to Archer model is presented for different material. As conclusion were defined that beam geometry has significant influence and the composition has low influence on transmission curves for shielding design for the range of energy applied to PET. (author)

  9. Learning curves of basic laparoscopic psychomotor skills in SINERGIA VR simulator.

    Science.gov (United States)

    Sánchez-Peralta, L F; Sánchez-Margallo, F M; Moyano-Cuevas, J L; Pagador, J B; Enciso, S; Gómez-Aguilera, E J; Usón-Gargallo, J

    2012-11-01

    Surgical simulators are currently essential within any laparoscopic training program because they provide a low-stakes, reproducible and reliable environment to acquire basic skills. The purpose of this study is to determine the training learning curve based on different metrics corresponding to five tasks included in SINERGIA laparoscopic virtual reality simulator. Thirty medical students without surgical experience participated in the study. Five tasks of SINERGIA were included: Coordination, Navigation, Navigation and touch, Accurate grasping and Coordinated pulling. Each participant was trained in SINERGIA. This training consisted of eight sessions (R1-R8) of the five mentioned tasks and was carried out in two consecutive days with four sessions per day. A statistical analysis was made, and the results of R1, R4 and R8 were pair-wise compared with Wilcoxon signed-rank test. Significance is considered at P value psychomotor skills that can be trained in SINERGIA. Therefore, and based on these results together with previous works, SINERGIA could be used as training tool with a properly designed training program.

  10. Three distal root canals in mandibular first molar with different canal configurations: Report of two cases and literature review

    Directory of Open Access Journals (Sweden)

    Parul Bansal

    2015-01-01

    Full Text Available With the increasing number of reports of aberrant root canal morphology, the clinician needs to be aware of the variable anatomy. Various case reports have been published with the finding of middle mesial canal in mandibular first molar, however finding of three distal canals in distal roots of mandibular first molar is rare. This article reports endodontic management of two mandibular first molars presented with three distal canals present in a single distal root (Sert and Bayirli type XVIII and distal and distolingual root.

  11. canal24

    Data.gov (United States)

    California Natural Resource Agency — Canal system center lines in the Central Valley of California and adjacent areas captured from 1:24,000-scale USGS topographic maps. Updates and modifications made...

  12. The fluid mechanics of root canal irrigation.

    Science.gov (United States)

    Gulabivala, K; Ng, Y-L; Gilbertson, M; Eames, I

    2010-12-01

    Root canal treatment is a common dental operation aimed at removing the contents of the geometrically complex canal chambers within teeth; its purpose is to remove diseased or infected tissue. The complex chamber is first enlarged and shaped by instruments to a size sufficient to deliver antibacterial fluids. These irrigants help to dissolve dying tissue, disinfect the canal walls and space and flush out debris. The effectiveness of the procedure is limited by access to the canal terminus. Endodontic research is focused on finding the instruments and clinical procedures that might improve success rates by more effectively reaching the apical anatomy. The individual factors affecting treatment outcome have not been unequivocally deciphered, partly because of the difficulty in isolating them and in making the link between simplified, general experimental models and the complex biological objects that are teeth. Explicitly considering the physical processes within the root canal can contribute to the resolution of these problems. The central problem is one of fluid motion in a confined geometry, which makes the dispersion and mixing of irrigant more difficult because of the absence of turbulence over much of the canal volume. The effects of treatments can be understood through the use of scale models, mathematical modelling and numerical computations. A particular concern in treatment is that caustic irrigant may penetrate beyond the root canal, causing chemical damage to the jawbone. In fact, a stagnation plane exists beyond the needle tip, which the irrigant cannot penetrate. The goal is therefore to shift the stagnation plane apically to be coincident with the canal terminus without extending beyond it. Needle design may solve some of the problems but the best design for irrigant penetration conflicts with that for optimal removal of the bacterial biofilm from the canal wall. Both irrigant penetration and biofilm removal may be improved through canal fluid

  13. The fluid mechanics of root canal irrigation

    International Nuclear Information System (INIS)

    Gulabivala, K; Ng, Y-L; Gilbertson, M; Eames, I

    2010-01-01

    Root canal treatment is a common dental operation aimed at removing the contents of the geometrically complex canal chambers within teeth; its purpose is to remove diseased or infected tissue. The complex chamber is first enlarged and shaped by instruments to a size sufficient to deliver antibacterial fluids. These irrigants help to dissolve dying tissue, disinfect the canal walls and space and flush out debris. The effectiveness of the procedure is limited by access to the canal terminus. Endodontic research is focused on finding the instruments and clinical procedures that might improve success rates by more effectively reaching the apical anatomy. The individual factors affecting treatment outcome have not been unequivocally deciphered, partly because of the difficulty in isolating them and in making the link between simplified, general experimental models and the complex biological objects that are teeth. Explicitly considering the physical processes within the root canal can contribute to the resolution of these problems. The central problem is one of fluid motion in a confined geometry, which makes the dispersion and mixing of irrigant more difficult because of the absence of turbulence over much of the canal volume. The effects of treatments can be understood through the use of scale models, mathematical modelling and numerical computations. A particular concern in treatment is that caustic irrigant may penetrate beyond the root canal, causing chemical damage to the jawbone. In fact, a stagnation plane exists beyond the needle tip, which the irrigant cannot penetrate. The goal is therefore to shift the stagnation plane apically to be coincident with the canal terminus without extending beyond it. Needle design may solve some of the problems but the best design for irrigant penetration conflicts with that for optimal removal of the bacterial biofilm from the canal wall. Both irrigant penetration and biofilm removal may be improved through canal fluid

  14. Development of Reinforcement Learning Algorithm for Automation of Slide Gate Check Structure in Canals

    Directory of Open Access Journals (Sweden)

    K. Shahverdi

    2016-02-01

    Full Text Available Introduction: Nowadays considering water shortage and weak management in agricultural water sector and for optimal uses of water, irrigation networks performance need to be improveed. Recently, intelligent management of water conveyance and delivery, and better control technologies have been considered for improving the performance of irrigation networks and their operation. For this affair, providing of mathematical model of automatic control system and related structures, which connected with hydrodynamic models, is necessary. The main objective of this research, is development of mathematical model of RL upstream control algorithm inside ICSS hydrodynamic model as a subroutine. Materials and Methods: In the learning systems, a set of state-action rules called classifiers compete to control the system based on the system's receipt from the environment. One could be identified five main elements of the RL: an agent, an environment, a policy, a reward function, and a simulator. The learner (decision-maker is called the agent. The thing it interacts with, comprising everything outside the agent, is called the environment. The agent selects an action based on existing state in the environment. When the agent takes an action and performs on environment, the environment goes new state and reward is assigned based on it. The agent and the environment continually interact to maximize the reward. The policy is a set of state-action pair, which have higher rewards. It defines the agent's behavior and says which action must be taken in which state. The reward function defines the goal in a RL problem. The reward function defines what the good and bad events are for the agent. The higher the reward, the better the action. The simulator provides environment information. In irrigation canals, the agent is the check structures. The action and state are the check structures adjustment and the water depth, respectively. The environment comprises the hydraulic

  15. Magmatic evolution of Panama Canal volcanic rocks: A record of arc processes and tectonic change.

    Directory of Open Access Journals (Sweden)

    David W Farris

    Full Text Available Volcanic rocks along the Panama Canal present a world-class opportunity to examine the relationship between arc magmatism, tectonic forcing, wet and dry magmas, and volcanic structures. Major and trace element geochemistry of Canal volcanic rocks indicate a significant petrologic transition at 21-25 Ma. Oligocene Bas Obispo Fm. rocks have large negative Nb-Ta anomalies, low HREE, fluid mobile element enrichments, a THI of 0.88, and a H2Ocalc of >3 wt. %. In contrast, the Miocene Pedro Miguel and Late Basalt Fm. exhibit reduced Nb-Ta anomalies, flattened REE curves, depleted fluid mobile elements, a THI of 1.45, a H2Ocalc of <1 wt. %, and plot in mid-ocean ridge/back-arc basin fields. Geochemical modeling of Miocene rocks indicates 0.5-0.1 kbar crystallization depths of hot (1100-1190°C magmas in which most compositional diversity can be explained by fractional crystallization (F = 0.5. However, the most silicic lavas (Las Cascadas Fm. require an additional mechanism, and assimilation-fractional-crystallization can reproduce observed compositions at reasonable melt fractions. The Canal volcanic rocks, therefore, change from hydrous basaltic pyroclastic deposits typical of mantle-wedge-derived magmas, to hot, dry bi-modal magmatism at the Oligocene-Miocene boundary. We suggest the primary reason for the change is onset of arc perpendicular extension localized to central Panama. High-resolution mapping along the Panama Canal has revealed a sequence of inward dipping maar-diatreme pyroclastic pipes, large basaltic sills, and bedded silicic ignimbrites and tuff deposits. These volcanic bodies intrude into the sedimentary Canal Basin and are cut by normal and subsequently strike-slip faults. Such pyroclastic pipes and basaltic sills are most common in extensional arc and large igneous province environments. Overall, the change in volcanic edifice form and geochemistry are related to onset of arc perpendicular extension, and are consistent with the

  16. Magmatic evolution of Panama Canal volcanic rocks: A record of arc processes and tectonic change

    Science.gov (United States)

    Cardona, Agustin; Montes, Camilo; Foster, David; Jaramillo, Carlos

    2017-01-01

    Volcanic rocks along the Panama Canal present a world-class opportunity to examine the relationship between arc magmatism, tectonic forcing, wet and dry magmas, and volcanic structures. Major and trace element geochemistry of Canal volcanic rocks indicate a significant petrologic transition at 21–25 Ma. Oligocene Bas Obispo Fm. rocks have large negative Nb-Ta anomalies, low HREE, fluid mobile element enrichments, a THI of 0.88, and a H2Ocalc of >3 wt. %. In contrast, the Miocene Pedro Miguel and Late Basalt Fm. exhibit reduced Nb-Ta anomalies, flattened REE curves, depleted fluid mobile elements, a THI of 1.45, a H2Ocalc of arc basin fields. Geochemical modeling of Miocene rocks indicates 0.5–0.1 kbar crystallization depths of hot (1100–1190°C) magmas in which most compositional diversity can be explained by fractional crystallization (F = 0.5). However, the most silicic lavas (Las Cascadas Fm.) require an additional mechanism, and assimilation-fractional-crystallization can reproduce observed compositions at reasonable melt fractions. The Canal volcanic rocks, therefore, change from hydrous basaltic pyroclastic deposits typical of mantle-wedge-derived magmas, to hot, dry bi-modal magmatism at the Oligocene-Miocene boundary. We suggest the primary reason for the change is onset of arc perpendicular extension localized to central Panama. High-resolution mapping along the Panama Canal has revealed a sequence of inward dipping maar-diatreme pyroclastic pipes, large basaltic sills, and bedded silicic ignimbrites and tuff deposits. These volcanic bodies intrude into the sedimentary Canal Basin and are cut by normal and subsequently strike-slip faults. Such pyroclastic pipes and basaltic sills are most common in extensional arc and large igneous province environments. Overall, the change in volcanic edifice form and geochemistry are related to onset of arc perpendicular extension, and are consistent with the idea that Panama arc crust fractured during collision

  17. The Impact of Grading on a Curve: Assessing the Results of Kulick and Wright's Simulation Analysis

    Science.gov (United States)

    Bailey, Gary L.; Steed, Ronald C.

    2012-01-01

    Kulick and Wright concluded, based on theoretical mathematical simulations of hypothetical student exam scores, that assigning exam grades to students based on the relative position of their exam performance scores within a normal curve may be unfair, given the role that randomness plays in any given student's performance on any given exam.…

  18. Numerical modeling of the 1964 Alaska tsunami in western Passage Canal and Whittier, Alaska

    Directory of Open Access Journals (Sweden)

    D. J. Nicolsky

    2010-12-01

    Full Text Available A numerical model of the wave dynamics in Passage Canal, Alaska during the Mw 9.2 megathrust earthquake is presented. During the earthquake, several types of waves were identified at the city of Whittier, located at the head of Passage Canal. The first wave is thought to have been a seiche, while the other two waves were probably triggered by submarine landslides. We model the seiche wave, landslide-generated tsunami, and tectonic tsunami in Passage Canal and compute inundation by each type of wave during the 1964 event. Modeled results are compared with eyewitness reports and an observed inundation line. Results of the numerical experiments let us identify where the submarine landslides might have occurred during the 1964 event. We identify regions at the head and along the northern shore of Passage Canal, where landslides triggered a wave that caused most of the damage in Whittier. An explanation of the fact that the 1964 tectonic tsunami in Whittier was unnoticed is presented as well. The simulated inundation by the seiche, landslide-generated tsunami, and tectonic tsunami can help to mitigate tsunami hazards and prepare Whittier for a potential tsunami.

  19. Viscoelastic assessment of anal canal function using acoustic reflectometry: a clinically useful technique.

    Science.gov (United States)

    Mitchell, Peter J; Klarskov, Niels; Telford, Karen J; Hosker, Gordon L; Lose, Gunnar; Kiff, Edward S

    2012-02-01

    Anal acoustic reflectometry is a new reproducible technique that allows a viscoelastic assessment of anal canal function. Five new variables reflecting anal canal function are measured: the opening and closing pressure, opening and closing elastance, and hysteresis. The aim of this study was to assess whether the parameters measured in anal acoustic reflectometry are clinically valid between continent and fecally incontinent subjects. This was an age- and sex-matched study of continent and incontinent women. The study was conducted at a university teaching hospital. One hundred women (50 with fecal incontinence and 50 with normal bowel control) were included in the study. Subjects were age matched to within 5 years. Parameters measured with anal acoustic reflectometry and manometry were compared between incontinent and continent groups using a paired t test. Diagnostic accuracy was assessed by the use of receiver operator characteristic curves. Four of the 5 anal acoustic reflectometry parameters at rest were significantly different between continent and incontinent women (eg, opening pressure in fecally incontinent subjects was 31.6 vs 51.5 cm H2O in continent subjects, p = 0.0001). Both anal acoustic reflectometry parameters of squeeze opening pressure and squeeze opening elastance were significantly reduced in the incontinent women compared with continent women (50 vs 99.1 cm H2O, p = 0.0001 and 1.48 vs 1.83 cm H2O/mm, p = 0.012). In terms of diagnostic accuracy, opening pressure at rest measured by reflectometry was significantly superior in discriminating between continent and incontinent women in comparison with resting pressure measured with manometry (p = 0.009). Anal acoustic reflectometry is a new, clinically valid technique in the assessment of continent and incontinent subjects. This technique, which assesses the response of the anal canal to distension and relaxation, provides a detailed viscoelastic assessment of anal canal function. This technique

  20. The Comparative Efficacy of Different Files in The Removal of Different Sealers in Simulated Root Canal Retreatment- An In-vitro Study.

    Science.gov (United States)

    Kanaparthy, Aruna; Kanaparthy, Rosaiah

    2016-05-01

    Root canal treatment enjoys a high success rate all over the world and has saved billions of teeth from extraction. However, there are instances of failure, the main causes being insufficient cleaning and inadequate obturation. In such cases the most conservative treatment option would be non-surgical retreatment. It requires regaining access to the entire root canal system through removal of the original root canal filling thus permitting further cleaning and re- obturation. Removal of gutta-percha and sealer becomes a critical step to gain access to the root canal system, remove necrotic tissue debris, bacteria and infected dentin. To compare and evaluate the efficacy of manual hand Hedstrom files and two rotary retreatment file systems ProTaper Universal retreatment files and Mtwo(R) (retreatment) files in the removal of root canal filling material during root canal retreatment and the influence of the type of sealers zinc oxide eugenol and AH plus on the presence of remaining debris in the reinstrumented canals in the apical, middle and coronal third. Sixty single rooted human premolar teeth were divided into 3 Groups of 20 teeth each Group I (20 Teeth): prepared using hand K Files, Group II (20 Teeth): prepared using ProTaper rotary system and Group III (20 Teeth): prepared using Mtwo rotary system. In Groups- IA, IIA, IIIA: (10 teeth each) Obturation was done using Zinc Oxide Eugenol sealer and gutta percha. In Groups- IB, IIB, IIIB: (10 teeth each) obturation was done with AH Plus sealer and gutta percha. All the teeth were subjected to retreatment. Groups IA and IB with Hedstrom files, Groups IIA and IIB with ProTaper retreatment files and for Groups IIIA and IIIB with Mtwo retreatment Files. The roots were longitudinally split and were observed under a stereomicroscope for remaining amount of filling material on the canal walls. Statistical analysis was done using One-way ANOVA (Analysis of variance) test and Tukey HSD Test. Mtwo(R) files showed

  1. Canal of Nuck hernia: a multimodality imaging review

    Energy Technology Data Exchange (ETDEWEB)

    Rees, Mitchell A. [University of Pittsburgh Medical Center, Department of Radiology, Pittsburgh, PA (United States); Squires, James E. [Children' s Hospital of Pittsburgh of UPMC, Department of Gastroenterology, Pittsburgh, PA (United States); Tadros, Sameh; Squires, Judy H. [University of Pittsburgh Medical Center, Department of Radiology, Pittsburgh, PA (United States); Children' s Hospital of Pittsburgh of UPMC, Department of Radiology, Pittsburgh, PA (United States)

    2017-07-15

    Canal of Nuck abnormalities are a rare but important cause of morbidity in girls, most often those younger than 5 years of age. The canal of Nuck, which is the female equivalent of the male processus vaginalis, is a protrusion of parietal peritoneum that extends through the inguinal canal and terminates in the labia majora. The canal typically obliterates early in life, but in some cases the canal can partially or completely fail to close, potentially resulting in a hydrocele or hernia of pelvic contents. Recognition of this entity is especially important in cases of ovarian hernia due to the risk of incarceration and torsion. We aim to increase awareness of this condition by reviewing the embryology, anatomy and diagnosis of canal of Nuck disorders with imaging findings on US, CT and MRI using several cases from a single institution. (orig.)

  2. Canal of Nuck hernia: a multimodality imaging review

    International Nuclear Information System (INIS)

    Rees, Mitchell A.; Squires, James E.; Tadros, Sameh; Squires, Judy H.

    2017-01-01

    Canal of Nuck abnormalities are a rare but important cause of morbidity in girls, most often those younger than 5 years of age. The canal of Nuck, which is the female equivalent of the male processus vaginalis, is a protrusion of parietal peritoneum that extends through the inguinal canal and terminates in the labia majora. The canal typically obliterates early in life, but in some cases the canal can partially or completely fail to close, potentially resulting in a hydrocele or hernia of pelvic contents. Recognition of this entity is especially important in cases of ovarian hernia due to the risk of incarceration and torsion. We aim to increase awareness of this condition by reviewing the embryology, anatomy and diagnosis of canal of Nuck disorders with imaging findings on US, CT and MRI using several cases from a single institution. (orig.)

  3. Remote sensing used for power curves

    International Nuclear Information System (INIS)

    Wagner, R; Joergensen, H E; Paulsen, U S; Larsen, T J; Antoniou, I; Thesbjerg, L

    2008-01-01

    Power curve measurement for large wind turbines requires taking into account more parameters than only the wind speed at hub height. Based on results from aerodynamic simulations, an equivalent wind speed taking the wind shear into account was defined and found to reduce the power standard deviation in the power curve significantly. Two LiDARs and a SoDAR are used to measure the wind profile in front of a wind turbine. These profiles are used to calculate the equivalent wind speed. The comparison of the power curves obtained with the three instruments to the traditional power curve, obtained using a cup anemometer measurement, confirms the results obtained from the simulations. Using LiDAR profiles reduces the error in power curve measurement, when these are used as relative instrument together with a cup anemometer. Results from the SoDAR do not show such promising results, probably because of noisy measurements resulting in distorted profiles

  4. Long-term hydrological simulation based on the Soil Conservation Service curve number

    Science.gov (United States)

    Mishra, Surendra Kumar; Singh, Vijay P.

    2004-05-01

    Presenting a critical review of daily flow simulation models based on the Soil Conservation Service curve number (SCS-CN), this paper introduces a more versatile model based on the modified SCS-CN method, which specializes into seven cases. The proposed model was applied to the Hemavati watershed (area = 600 km2) in India and was found to yield satisfactory results in both calibration and validation. The model conserved monthly and annual runoff volumes satisfactorily. A sensitivity analysis of the model parameters was performed, including the effect of variation in storm duration. Finally, to investigate the model components, all seven variants of the modified version were tested for their suitability.

  5. Type III apical transportation of root canal

    Directory of Open Access Journals (Sweden)

    Shiv P Mantri

    2012-01-01

    Full Text Available Procedural accidents leading to complications such as canal transportation have been ascribed to inapt cleaning and shaping concepts. Canal transportation is an undesirable deviation from the natural canal path. Herewith a case of apical transportation of root canal resulting in endodontic retreatment failure and its management is presented. A healthy 21-year-old young male presented discomfort and swelling associated with painful endodontically retreated maxillary incisor. Radiograph revealed periradicular radiolucency involving underfilled 11 and overfilled 12. Insufficiently obturated 11 exhibited apical transportation of canal. This type III transportation was treated by periradicular surgery and repair using white mineral trioxide aggregate (MTA. Comfortable asymptomatic patient presented uneventful healing at third and fourth month recall visits. A decrease in the size of radiolucency in radiograph supported the clinical finding. In the present case, MTA is useful in repairing the transportation defect. The result of these procedures is predictable and successful.

  6. The nonlinear Maxwell-type model for viscoelastoplastic materials: simulation of temperature influence on creep, relaxation and strain-stress curves

    Directory of Open Access Journals (Sweden)

    Andrew V. Khokhlov

    2017-04-01

    Full Text Available The nonlinear Maxwell-type constitutive relation with two arbitrary material functions for viscoelastoplastic multi-modulus materials is studied analytically in uniaxial isothermic case to reveal the model abilities and applicability scope and to develop techniques of its identification, tuning and fitting. The constitutive equation is aimed at adequate modeling of the rheological phenomena set which is typical for reonomic materials exhibiting non-linear hereditary properties, strong strain rate sensitivity, secondary creep, yielding at constant stress, tension compression asymmetry and such temperature effects as increase of material compliance, strain rate sensitivity and rates of dissipation, relaxation, creep and plastic strain accumulation with temperature growth. The model is applicable for simulation of mechanical behaviour of various polymers, their solutions and melts, solid propellants, sand-asphalt concretes, composite materials, titanium and aluminum alloys, ceramics at high temperature and so on. To describe the influence of temperature on material mechanical behavior (under isothermic conditions, two scalar material parameters of the model (viscosity coefficient and “modulus of elasticity” are considered as a functions of temperature level. The general restrictions on their properties which are necessary and sufficient for adequate qualitative description of the basic thermomechanical phenomena related to typical temperature influence on creep and relaxation curves, creep recovery curves, creep curves under step-wise loading and quasi-static stress-strain curves of viscoelastoplastic materials are obtained. The restrictions are derived using systematic analytical study of general qualitative features of the theoretic creep and relaxation curves, creep curves under step-wise loading, long-term strength curves and stress-strain curves at constant strain or stress rates generated by the constitutive equation (under minimal

  7. Mandibular molar with five root canals.

    Science.gov (United States)

    Barletta, Fernando Branco; Dotto, Sidney Ricardo; Reis, Magda de Sousa; Ferreira, Ronise; Travassos, Rosana Maria Coelho

    2008-12-01

    The purpose of this study was to demonstrate the importance of knowledge of the internal anatomy of root canals for the success of endodontic treatment. Lack of knowledge of anatomic variations and their characteristics in different teeth has been pointed out as one of the main causes of endodontic therapy failure. In this report, the authors describe the endodontic treatment of a mandibular first molar with five root canals, evaluate the rate of occurrence of this number of canals, and discuss the importance of their identification and treatment.

  8. Lumbar Vertebral Canal Diameters in Adult Ugandan Skeletons ...

    African Journals Online (AJOL)

    Background: Normal values of lumbar vertebral canal diameters are useful in facilitating diagnosis of lumbar vertebral canal stenosis. Various studies have established variation on values between different populations, gender, age, and ethnic groups. Objectives: To determine the lumbar vertebral canal diameters in adult ...

  9. The Use of a Reciprocating Handpiece to Create a Glide Path in Curved Canals: Comparison with Manual Glide Path Preparation

    Science.gov (United States)

    2016-06-01

    instruments into the root canal system, manufacturers recommend creating a glide path to reduce the risk of instrument fracture due to taper lock . This...Results The two groups had almost identical mean and standard...The groups had identical median values of 85 seconds, and there was no significant difference between the groups (Mann-Whitney U test; p=0.15; two

  10. Impact of canal water shortages on groundwater in the Lower Bari Doab Canal system in Pakistan

    International Nuclear Information System (INIS)

    Shakir, A.S.; Rehman, H.U.; Khan, N.M.; Qazi, A.U.

    2011-01-01

    This paper presents rigorous analysis of shortage of canal water supplies, crop water requirements, and groundwater use and its quality in the command of Lower Bari Doab Canal, Pakistan. The annual canal water supplies are 36% less than the crop water requirements. This shortage further increases to 56% if actual canal supplies (averaged over last ten years) are compared with the crop water requirement. The groundwater levels are depleting at the rate of 30 to 40 cm per year in most parts of the LBDC command and this tendency of lowering may increase in future due to further increase in crop water requirements. The analysis of data for the last seven years indicate that quality of groundwater in most parts of LBDC command is generally good (64% of the area) or marginally acceptable (28%) for irrigation use. However, declining trends in groundwater quality are visible and can create long term sustain ability problems if proper remedial actions are not taken well in time. (author)

  11. Gender and laterality in semicircular canal dehiscence syndrome.

    Science.gov (United States)

    Karimnejad, K; Czerny, M S; Lookabaugh, S; Lee, D J; Mikulec, A A

    2016-08-01

    To determine if there is gender or laterality predilection in patients with semicircular canal dehiscence syndrome. A multi-institutional chart review was performed to identify patients diagnosed with semicircular canal dehiscence between 2000 and 2015. A systematic literature search was conducted using PubMed to further identify patients with semicircular canal dehiscence. Age, gender and laterality data were collected. Statistical analysis was performed to evaluate for gender or laterality preponderance. A total of 682 patients with semicircular canal dehiscence were identified by literature and chart review. Mean age of diagnosis was 49.75 years (standard deviation = 15.33). Semicircular canal dehiscence was associated with a statistically significant female predominance (chi-square = 7.185, p = 0.007); the female-to-male ratio was 1.2 to 1. Left-sided semicircular canal dehiscence was most common, followed by right-sided then bilateral (chi-square = 23.457, p < 0.001). Semicircular canal dehiscence syndrome is most commonly left-sided and exhibits a female predominance. This may be secondary to morphological cerebral hemisphere asymmetries in both sexes and a predilection of women to seek more medical care than men.

  12. Environmental pollution and shipping feasibility of the Nicaragua Canal

    International Nuclear Information System (INIS)

    Chen, Jihong; Zeng, Xin; Deng, Yibing

    2016-01-01

    In recent years, the Nicaraguan government's renewed interest in constructing this interoceanic canal has once again aroused widespread concern, particularly in the global shipping industry. The project's immense ecological risks, coupled with the recent expansions of both the Panama Canal and the Suez Canal, have raised questions among scientists and experts about its viability. Whether the Nicaragua Canal is really feasible for international shipping, given its high marine pollution risks, requires the further study. This paper discusses and analyses the feasibility of the Nicaragua Canal in the context of its environmental impact and value as a shipping service. This paper aims to provide an important information reference to inform strategic decision-making among policymakers and stakeholders. Our research results indicate that the environmental complexity, economic costs and safety risks of building a new transoceanic canal are simply too high to justify the project. - Highlights: • The Nicaragua Canal is a long-standing controversial maritime project. • We develop specific analysis of the high environmental pollution risks of the canal. • The shipping service feasibility of the canal is faced with great uncertainty. • The government and stakeholders are suggested to be discreet to the mega project.

  13. The failures of root canal preparation with hand ProTaper.

    Science.gov (United States)

    Bătăiosu, Marilena; Diaconu, Oana; Moraru, Iren; Dăguci, C; Tuculină, Mihaela; Dăguci, Luminiţa; Gheorghiţă, Lelia

    2012-07-01

    The failures of root canal preparation are due to some anatomical deviation (canal in "C" or "S") and some technique errors. The technique errors are usually present in canal root cleansing and shaping stage and are the result of endodontic treatment objectives deviation. Our study was made on technique errors while preparing the canal roots with hand ProTaper. Our study was made "in vitro" on 84 extracted teeth (molars, premolars, incisors and canines). The canal root of these teeth were cleansed and shaped with hand ProTaper by crown-down technique and canal irrigation with NaOCl(2,5%). The dental preparation control was made by X-ray. During canal root preparation some failures were observed like: canal root overinstrumentation, zipping and stripping phenomenon, discarded and/or fractured instruments. Hand ProTaper represents a revolutionary progress of endodontic treatment, but a deviation from accepted rules of canal root instrumentation can lead to failures of endodontic treatment.

  14. Numerical simulation of the double pits stress concentration in a curved casing inner surface

    Directory of Open Access Journals (Sweden)

    Wei Yan

    2016-12-01

    Full Text Available Sour or sweet oil fields development is common in recent years. Casing and tubing are usually subjected to pitting corrosion because of exposure to the strong corrosion species, such as CO2, H2S, and saline water. When the corrosion pits formed in the casing inner surface, localized stress concentration will occur and the casing strength will be degraded. Thus, it is essential to evaluate the degree of stress concentration factor accurately. This article performed a numerical simulation on double pits stress concentration factor in a curved inner surface using the finite element software ABAQUS. The results show that the stress concentration factor of double pits mainly depends on the ratio of two pits distance to the pit radius (L/R. It should not be only assessed by the absolute distance between the two pits. When the two pits are close and tangent, the maximum stress concentration factor will appear on the inner tangential edges. Stress concentration increased by double pits in a curved casing inner surface is more serious than that in a flat surface. A correction factor of 1.9 was recommended in the curved inner surface double pits stress concentration factor predict model.

  15. Infected Hydrocele of the Canal of Nuck

    Directory of Open Access Journals (Sweden)

    Parkash Mandhan

    2013-01-01

    Full Text Available Hydrocele of the canal of Nuck in children is rare. It may present as incarcerated inguinal hernia and necessitates emergency exploration. Risk of infection in hydrocele of the canal of nuck is very rare. We present a case report of a 5-year-old girl who presented with a left tender inguinolabial region swelling with fever, tachycardia, and mild dehydration. The clinical features were suggestive of strangulated left inguinal hernia and further imaging and surgical exploration revealed it to be an infected hydrocele of the canal of Nuck. High ligation and hydrocelectomy were performed. Hydrocele of the canal of Nuck in a female child presenting with an inguinal swelling should be considered in differential diagnosis.

  16. Algorithm for Automatic Generation of Curved and Compound Twills

    Institute of Scientific and Technical Information of China (English)

    WANG Mei-zhen; WANG Fu-mei; WANG Shan-yuan

    2005-01-01

    A new arithmetic using matrix left-shift functions for the quicker generation of curved and compound twills is introduced in this paper. A matrix model for the generation of regular, curved and compound twill structures is established and its computing simulation realization are elaborated. Examples of the algorithm applying in the simulation and the automatic generation of curved and compound twills in fabric CAD are obtained.

  17. Incidence and characteristics of mandibular accessory canals: A radiographic investigation.

    Science.gov (United States)

    Borgonovo, Andrea Enrico; Taschieri, Silvio; Vavassori, Virna; Re, Dino; Francetti, Luca; Corbella, Stefano

    2017-11-01

    The aim of the present study was to explore, through tridimensional reconstructions of cone-beam computed tomography (CBCT) scans, the presence and the characteristics of mandibular accessory canals. For each included participant, the presence of accessory canals was recorded. The diameter of the canal, as well as the distance between the canal walls and the walls of the mandibular bone (lingual, buccal, cranial and caudal), were measured and recorded. Mandibular accessory canals could be found in 8.8% of participants. Retromolar canals were the most frequently found accessory mandibular canals. Accessory mandibular canals were found in a relatively high number of participants through the examination of CBCT scans and tridimensional reconstruction. The presence of such structures should be considered cautiously when planning and performing surgical interventions in mandibular area. © 2017 John Wiley & Sons Australia, Ltd.

  18. A pilot study to assess adductor canal catheter tip migration in a cadaver model.

    Science.gov (United States)

    Leng, Jody C; Harrison, T Kyle; Miller, Brett; Howard, Steven K; Conroy, Myles; Udani, Ankeet; Shum, Cynthia; Mariano, Edward R

    2015-04-01

    An adductor canal catheter may facilitate early ambulation after total knee arthroplasty, but there is concern over preoperative placement since intraoperative migration of catheters may occur from surgical manipulation and result in ineffective analgesia. We hypothesized that catheter type and subcutaneous tunneling may influence tip migration for preoperatively inserted adductor canal catheters. In a male unembalmed human cadaver, 20 catheter insertion trials were divided randomly into one of four groups: flexible epidural catheter either tunneled or not tunneled; or rigid stimulating catheter either tunneled or not tunneled. Intraoperative patient manipulation was simulated by five range-of-motion exercises of the knee. Distance and length measurements were performed by a blinded regional anesthesiologist. Changes in catheter tip to nerve distance (p = 0.225) and length of catheter within the adductor canal (p = 0.467) were not different between the four groups. Two of five non-tunneled stimulating catheters (40 %) were dislodged compared to 0/5 in all other groups (p = 0.187). A cadaver model may be useful for assessing migration of regional anesthesia catheters; catheter type and subcutaneous tunneling may not affect migration of adductor canal catheters based on this preliminary study. However, future studies involving a larger sample size, actual patients, and other catheter types are warranted.

  19. 21 CFR 872.3820 - Root canal filling resin.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Root canal filling resin. 872.3820 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3820 Root canal filling resin. (a) Identification. A root canal filling resin is a device composed of material, such as methylmethacrylate, intended...

  20. Mejoras en el canal de Panamá

    Directory of Open Access Journals (Sweden)

    Brandl, Charles McG.

    1963-07-01

    Full Text Available The Panama Canal, together with the Suez Canal, is an engineering accomplishment which is now regarded as a master work marking the initiation of modern civil engineering. Other projects, also of great magnitude, do not seem to maintain the reputation of the above two, because they cannot continue to serve their function with sustained usefulness in the new circumstances of today. The Panama Canal, with its limited dock capacity, and the narrow, so called Serpent, canal, has had to cope with a continuously increasing volume of shipping traffic; a natural consequence of commercial evolution. In order to keep up with these increasing demands, it has been necessary to carry out an almost uninterrupted series of modifications and improvements, affecting both the method of operation and organisation, and the actual nature of the canal. Thanks to these alterations the Panama Canal has continued to maintain, at least nominally, an adequate standard of functional efficiency. At present the canal is being widened over certain sections to enable the easy passage of ships of great displacement. The work is being done very rapidly, and in order to gain time, it has been distributed to various contractors simultaneously.El canal a través del ismo de Panamá es una obra de ingeniería civil que, junto con el de Suez, empiezan ya a clasificarse como obras maestras que señalan el primer jalón del desarrollo de la ingeniería moderna. Otras obras, también importantes, no conservan, sin embargo, la misma reputación que aquéllas, por no seguir un paralelismo con las exigencias en cada época. El canal de Panamá, con sus exclusas, y angosto paso llamado de la. Culebra, ha tenido que afrontar un tráfico creciente de navíos que siguen la evolución del tiempo. Para conseguir este paralelismo, tanto el material de explotación como la organización, dragados y mejoras, han tenido que conocer una sucesión ininterrumpida de modificaciones que han permitido

  1. Comparison of the rheological properties of four root canal sealers

    Institute of Scientific and Technical Information of China (English)

    Seok Woo Chang; Kwang Shik Bae; Young-Kyu Lee; Qiang Zhu; Won Jun Shon; Woo Cheol Lee; Kee Yeon Kum; Seung Ho Baek; In Bog Lee; Bum-Soon Lim

    2015-01-01

    The flowability of a root canal sealer is clinically important because it improves the penetration of the sealer into the complex root canal system. The purpose of this study was to compare the flowabilities of four root canal sealers, measured using the simple press method (ISO 6876), and their viscosities, measured using a strain-controlled rheometer. A newly developed, calcium phosphate-based root canal sealer (Capseal) and three commercial root canal sealers (AH Plus, Sealapex and Pulp Canal Sealer EWT) were used in this study. The flowabilities of the four root canal sealers were measured using the simple press method (n55) and their viscosities were measured using a strain-controlled rheometer (n55). The correlation between these two values was statistically analysed using Spearman’s correlation test. The flow diameters and the viscosities of the root canal sealers were strongly negatively correlated (r520.8618). The viscosity of Pulp Canal Sealer EWT was the lowest and increased in the following order:AH Plus,Sealapex,Capseal (P,0.05). All of the tested root canal sealers showed characteristic time-and temperature-dependent changes in their rheological properties. The viscosities measured using the strain-controlled rheometer were more precise than the flowabilities measured using the simple press method, suggesting that the rheometer can accurately measure the rheological properties of root canal sealers.

  2. Management of Acquired Atresia of the External Auditory Canal.

    Science.gov (United States)

    Bajin, Münir Demir; Yılmaz, Taner; Günaydın, Rıza Önder; Kuşçu, Oğuz; Sözen, Tevfik; Jafarov, Shamkal

    2015-08-01

    The aim was to evaluate surgical techniques and their relationship to postoperative success rate and hearing outcomes in acquired atresia of the external auditory canal. In this article, 24 patients with acquired atresia of the external auditory canal were retrospectively evaluated regarding their canal status, hearing, and postoperative success. Acquired stenosis occurs more commonly in males with a male: female ratio of 2-3:1; it seems to be a disorder affecting young adults. Previous ear surgery (13 patients, 54.2%) and external ear trauma (11 patients, 45.8%) were the main etiological factors of acquired ear canal stenosis. Mastoidectomy (12/13) and traffic accidents (8/11) comprise the majority of these etiological factors. Endaural incision is performed in 79.2% and postauricular incision for 20.8% of cases during the operation. As types of surgical approach, transcanal (70.8%), transmastoid (20.8%), and combined (8.4%) approaches are chosen. The atretic plate is generally located at the bony-cartilaginous junction (37.5%) and in the cartilaginous canal (33.3%); the bony canal is involved in a few cases only. Preserved healthy canal skin, split- or full-thickness skin grafts, or pre- or postauricular skin flaps are used to line the ear canal, but preserved healthy canal skin is preferred. The results of surgery are generally satisfactory, and complications are few if surgical principles are followed.

  3. Endodontic Shaping Performance Using Nickel–Titanium Hand and Motor ProTaper Systems by Novice Dental Students

    OpenAIRE

    Tu, Ming-Gene; Chen, San-Yue; Huang, Heng-Li; Tsai, Chi-Cheng

    2008-01-01

    Preparing a continuous tapering conical shape and maintaining the original shape of a canal are obligatory in root canal preparation. The purpose of this study was to compare the shaping performance in simulated curved canal resin blocks of the same novice dental students using hand-prepared and engine-driven nickel–titanium (NiTi) rotary ProTaper instruments in an endodontic laboratory class. Methods: Twenty-three fourth-year dental students attending China Medical University Dental Schoo...

  4. Comparative study of root-canal shaping with stainless steel and rotary NiTi files performed by preclinical dental students.

    Science.gov (United States)

    Alrahabi, Mothanna

    2015-01-01

    We evaluated the use of NiTi rotary and stainless steel endodontic instruments for canal shaping by undergraduate students. We also assessed the quality of root canal preparation as well as the occurrence of iatrogenic events during instrumentation. In total, 30 third-year dental students attending Taibah University Dental College prepared 180 simulated canals in resin blocks with NiTi rotary instruments and stainless steel hand files. Superimposed images were prepared to measure the removal of material at different levels from apical termination using the GSA image analysis software. Preparation time, procedural accidents, and canal shape after preparation were analyzed using χ 2 and t-tests. The statistical significance level was set at P instruments and stainless steel files; the former was associated with shorter preparation time, less ledge formation (1.1% vs. 14.4%), and greater instrument fracture (5.56% vs. 1.1%). These results indicate that NiTi rotary instruments result in better canal geometry and cause less canal transportation. Manual instrumentation using stainless steel files is safer than rotary instrumentation for inexperienced students. Intensive preclinical training is a prerequisite for using NiTi rotary instruments. These results prompted us to reconsider theoretical and practical coursework when teaching endodontics.

  5. Air-Leak Effects on Ear-Canal Acoustic Absorbance

    Science.gov (United States)

    Rasetshwane, Daniel M.; Kopun, Judy G.; Gorga, Michael P.; Neely, Stephen T.

    2015-01-01

    Objective: Accurate ear-canal acoustic measurements, such as wideband acoustic admittance, absorbance, and otoacoustic emissions, require that the measurement probe be tightly sealed in the ear canal. Air leaks can compromise the validity of the measurements, interfere with calibrations, and increase variability. There are no established procedures for determining the presence of air leaks or criteria for what size leak would affect the accuracy of ear-canal acoustic measurements. The purpose of this study was to determine ways to quantify the effects of air leaks and to develop objective criteria to detect their presence. Design: Air leaks were simulated by modifying the foam tips that are used with the measurement probe through insertion of thin plastic tubing. To analyze the effect of air leaks, acoustic measurements were taken with both modified and unmodified foam tips in brass-tube cavities and human ear canals. Measurements were initially made in cavities to determine the range of critical leaks. Subsequently, data were collected in ears of 21 adults with normal hearing and normal middle-ear function. Four acoustic metrics were used for predicting the presence of air leaks and for quantifying these leaks: (1) low-frequency admittance phase (averaged over 0.1–0.2 kHz), (2) low-frequency absorbance, (3) the ratio of compliance volume to physical volume (CV/PV), and (4) the air-leak resonance frequency. The outcome variable in this analysis was the absorbance change (Δabsorbance), which was calculated in eight frequency bands. Results: The trends were similar for both the brass cavities and the ear canals. ΔAbsorbance generally increased with air-leak size and was largest for the lower frequency bands (0.1–0.2 and 0.2–0.5 kHz). Air-leak effects were observed in frequencies up to 10 kHz, but their effects above 1 kHz were unpredictable. These high-frequency air leaks were larger in brass cavities than in ear canals. Each of the four predictor variables

  6. Middle mesial canals in mandibular molars: incidence and related factors.

    Science.gov (United States)

    Nosrat, Ali; Deschenes, Raney J; Tordik, Patricia A; Hicks, M Lamar; Fouad, Ashraf F

    2015-01-01

    Although the internal anatomy of mandibular molars has been extensively studied, information about middle mesial (MM) canals is limited. The primary aim of this retrospective study was to evaluate the incidence of MM canals in mandibular first and second molars. The secondary aim was to correlate the incidence of MM canals with variables of molar type, sex, age, ethnicity, and presence of a second distal canal. All mature permanent first and second mandibular molars treated from August 2012 to May 2014 were included in the analysis. After completion of root canal instrumentation in all main canals, the clinician inspected the isthmus area of the mesial root using the dental operating microscope. If there was a catch point in this area with a file or explorer, the operator spent more time attempting to negotiate an MM canal. Seventy-five mandibular first and second molars were treated during the specified period. Fifteen (20%) teeth had negotiable MM canals. The incidence of MM canals was 32.1% in patients ≤ 20 years old, 23.8% in patients 21-40 years old, and 3.8% in patients > 40 years. Analysis of data revealed a significant difference in the distribution of MM canals among different age groups (P molar type, and presence of a second distal canal were not significant. The incidence of negotiable MM canals overall and their frequency of identification in younger patients were higher than in previous reports. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  7. Radiographic evaluation of the quality of root canal obturation of single-matched cone Gutta-percha root canal filling versus hot lateral technique

    Directory of Open Access Journals (Sweden)

    Randa Suleiman Obeidat

    2014-01-01

    Full Text Available Aim: The aim of this study is to evaluate radiographically the quality of root canal filling in mesiodistal and buccolingual view when comparing matched cone condensation and warm lateral Gutta-percha condensation using system B heating instrument in a low-heat warm lateral condensation technique in0 vitro. Materials and Methods: A total of 40 mandibular premolars with straight single canals were divided into two groups with 20 each. The root canals were shaped by hand file and Revo-S rotary files to size (25, 0.06 at the end point, then they filled by Gutta-percha cone and meta-seal sealer. In group A, a single matched cone technique was used to fill the root canals. In group B, a hot lateral condensation using system B instrument at 101°C was performed. Result: The result of this study showed no significant difference in density of Gutta-percha fill in apical and coronal two-third when comparing matched cone root canal filling and hot lateral technique (P > 0.05. The only significant difference (P < 0.05 was in matched cone between buccolingual and mesiodistal view in the coronal two-third. Conclusion: Within the limitation of this study, single matched cone technique has a good density in the apical one-third as that of the hot lateral technique so it may be used for filling narrow canals. In the coronal two-third of the root canal, single matched cone technique showed inferior density of root canal filling which can be improved by using accessory cones Gutta-percha in wide canal.

  8. Newer Root Canal Irrigants in Horizon: A Review

    Directory of Open Access Journals (Sweden)

    Sushma Jaju

    2011-01-01

    Full Text Available Sodium hypochloride is the most commonly used endodontic irrigant, despite limitations. None of the presently available root canal irrigants satisfy the requirements of ideal root canal irrigant. Newer root canal irrigants are studied for potential replacement of sodium hypochloride. This article reviews the potential irrigants with their advantages and limitations with their future in endodontic irrigation.

  9. A comparative study for different shielding material composition and beam geometry applied to PET facilities: simulated transmission curves

    OpenAIRE

    Hoff, Gabriela; Costa, Paulo Roberto

    2013-01-01

    The aim of this work is to simulate transmission data for different beam geometry and material composition in order to evaluate the effect of these parameters on transmission curves. The simulations are focused on outgoing spectra for shielding barriers used in PET facilities. The behavior of the transmission was evaluated as a function of the shielding material composition and thickness using Geant4 Monte Carlo code, version 9.2 p 03.The application was benchmarked for barited mortar and com...

  10. Neuronal hyperplasia in the anal canal

    DEFF Research Database (Denmark)

    Fenger, C; Schrøder, H D

    1990-01-01

    In a consecutive series of minor surgical specimens from the anal canal, neuronal hyperplasia was found in nine of 56 haemorrhoidectomy specimens and in four of 23 fibrous polyps. In an additional series of 14 resections of the anal canal, neuronal hyperplasia was present in six cases, of which f...

  11. THE BUSINESS OF THE CANAL: THE ECONOMICS AND POLITICS OF THE CARTER ADMINISTRATION’S PANAMA CANAL ZONE INITIATIVE, 1978

    Directory of Open Access Journals (Sweden)

    Mary C. Swilling

    2004-01-01

    Full Text Available The Carter-Torrijos Treaty of 1978, the initiative to relinquish controi of the Panama Canal Zone to the Republic of Panama, allowed Panama for the first time in its short history to become an autonomous nation and to take control of its destiny as a global trading crossroads. Conservatives rallied against President Carter and accused him of jeopardizing U. S. security and hegemony. Fears were that Panama did not have the economic or technical resources to maintain Canal operations, lacked the administrative knowledge and resources to manage the business of the Canal, lacked the military presence to insure security of the Canal, and did not have the political and social will to maintain the environmental integrity of the region. In short, disastrous results were predicted. Carter prevailed. December 31, 1999 saw the surrender of the Canal Zone, and all its facilities, to Panama. This paper discusses events that precipitated Carter’s decision, economic and political arguments presented during the 1977-78 debate, implementation of the treaty, and an evaluation of the ‘business of the Canal’ today.

  12. Hydrology and environmental aspects of Erie Canal (1817-99)

    Science.gov (United States)

    Langbein, Walter Basil

    1976-01-01

    As the first major water project in the United States, the old Erie Canal provides an example of the hydrological and environmental consequences of water development. The available record shows that the project aroused environmental fears that the canal might be impaired by the adverse hydrologic effects of land development induced by the canal. Water requirements proved greater than anticipated, and problems of floods and hydraulic inefficiencies beset navigation throughout its history. The Erie Canal proved the practicality of major hydraulic works to the extent that operations and maintenance could cope with the burdens of deficiencies in design. The weight of prior experience that upland streams, such as the Potomac and Mohawk Rivers, had proved unsatisfactory for dependable navigation, led to a decision to build an independent canal which freed the location from the constraints of river channels and made possible a cross-country water route directly to Lake Erie. The decision on dimensioning the canal prism--chiefly width and depth-involved balance between a fear of building too small and thus not achieving the economic potentials, and a fear of building too expensively. The constraints proved effective, and for the first part of its history the revenues collected were sufficient to repay all costs. So great was the economic advantage of the canal that the rising trend in traffic soon induced an enlargement of the canal cross section, based upon a new but riskier objective-build as large as the projected trend in toll revenues would finance. The increased revenues did not materialize. Water supplies were a primary concern for both the planners and the operators of the canal. Water required for lockage, although the most obvious to the planners, proved to be a relatively minor item compared with the amounts of water that were required to compensate for leakage through the bed and banks of the canal. Leakage amounted to about 8 inches of depth per day. The total

  13. Single-rooted maxillary first molar with a single canal: endodontic retreatment.

    Science.gov (United States)

    de la Torre, Francisco; Cisneros-Cabello, Rafael; Aranguren, José Luis; Estévez, Roberto; Velasco-Ortega, Eugenio; Segura-Egea, Juan José

    2008-12-01

    This case report presents an unusual root canal system in a maxillary first molar tooth: a single canal in a single root. The endodontic access cavity displayed only 1 canal orifice. This case demonstrated that: 1) clinicians must have adequate knowledge about root canal morphology and its variations; 2) the location and morphology of root canals should be identified radiologically before the root canal treatment; and 3) careful examination of radiographs and the internal anatomy of teeth is essential.

  14. The failures of root canal preparation with hand ProTaper

    OpenAIRE

    Bătăiosu, Marilena; Diaconu, Oana; Moraru, Iren; Dăguci, C.; Ţuculină, Mihaela; Dăguci, Luminiţa; Gheorghiţă, Lelia

    2012-01-01

    The failures of root canal preparation are due to some anatomical deviation (canal in “C” or “S”) and some technique errors. The technique errors are usually present in canal root cleansing and shaping stage and are the result of endodontic treatment objectives deviation. Objectives: Our study was made on technique errors while preparing the canal roots with hand ProTaper. Methodology: Our study was made “in vitro” on 84 extracted teeth (molars, premolars, incisors and canines). The canal roo...

  15. Shaping ability of reciprocating motion of WaveOne and HyFlex in moderate to severe curved canals: A comparative study with cone beam computed tomography

    Science.gov (United States)

    Simpsy, Gurram Samuel; Sajjan, Girija S.; Mudunuri, Padmaja; Chittem, Jyothi; Prasanthi, Nalam N. V. D.; Balaga, Pankaj

    2016-01-01

    Introduction: M-Wire and reciprocating motion of WaveOne and controlled memory (CM) wire) of HyFlex were the recent innovations using thermal treatment. Therefore, a study was planned to evaluate the shaping ability of reciprocating motion of WaveOne and HyFlex using cone beam computed tomography (CBCT). Methodology: Forty-five freshly extracted mandibular teeth were selected and stored in saline until use. All teeth were scanned pre- and post-operatively using CBCT (Kodak 9000). All teeth were accessed and divided into three groups. (1) Group 1 (control n = 15): Instrumented with ProTaper. (2) Group 2 (n = 15): Instrumented with primary file (8%/25) WaveOne. (3) Group 3 (n = 15): Instrumented with (4%/25) HyFlex CM. Sections at 1, 3, and 5 mm were obtained from the pre- and post-operative scans. Measurement was done using CS3D software and Adobe Photoshop software. Apical transportation and degree of straightening were measured and statistically analyzed. Results: HyFlex showed lesser apical transportation when compared to other groups at 1 and 3 mm. WaveOne showed lesser degree of straightening when compared to other groups. Conclusion: This present study concluded that all systems could be employed in routine endodontics whereas HyFlex and WaveOne could be employed in severely curved canals. PMID:27994323

  16. Speed choice and steering behavior in curve driving

    NARCIS (Netherlands)

    Winsum, W. van; Godthelp, J.

    1996-01-01

    The relation between speed choice and steering performance during curve negotiation was studied in a driving simulator. The hypothesis was that curve radius and steering competence both affect steering error during curve driving, resulting in compensatory speed choice. In this, the control of safety

  17. Root canal treatment of mandibular second premolar tooth with taurodontism

    Directory of Open Access Journals (Sweden)

    Vujašković Mirjana

    2008-01-01

    Full Text Available INTRODUCTION Taurodontism is a morphoanatomical change in the shape of a tooth. An enlarged body of a tooth with smaller than usual roots is a characteristic feature. Internal tooth anatomy correlates with this appearance, which means that a taurodontal tooth has a large pulp chamber and apically positioned furcations. This dental anomaly may be associated with different syndromes and congenital discoders. CASE OUTLINE The case report presents the patient of a rare case of taurodontism in the mandibular second premolar with chronic periodontitis. Endodontic treatment was performed after dental history and clinical examination. Special care is required in all segments of endodontic treatment of a taurodontal tooth from the identification orifice, canal exploration, determining working length, cleaning and shaping and obturation of the root canal. Precurved K-file was used for canal exploration and location of the furcation. One mesial and one distal canal with the buccal position were identified in the apical third of the root canal. The working lengths of two canals were determined by radiographic interpretation with two K-files in each canal and verified with the apex locator. During canal instrumentation, the third canal was located in the disto-lingual position. The working length of the third canal was established using the apex locator. CONCLUSION Thorough knowledge of tooth anatomy and its variations can lead to lower percentage of endodontic failure. Each clinical case involving these teeth should be investigated carefully, clinically and radiographically to detect additional root canals. High quality radiographs from different angles and proper instrumentarium improve the quality of endodontic procedure.

  18. [Upper lateral incisor with 2 canals].

    Science.gov (United States)

    Fabra Campos, H

    1991-01-01

    Clinical case summary of the patient with an upper lateral incisor with two root canals. The suspicion that there might be an anatomic anomaly in the root that includes a complex root canal system was made when an advanced radicular groove was detected in the lingual surface or an excessively enlarged cingulum.

  19. Environmental pollution and shipping feasibility of the Nicaragua Canal.

    Science.gov (United States)

    Chen, Jihong; Zeng, Xin; Deng, Yibing

    2016-12-15

    In recent years, the Nicaraguan government's renewed interest in constructing this interoceanic canal has once again aroused widespread concern, particularly in the global shipping industry. The project's immense ecological risks, coupled with the recent expansions of both the Panama Canal and the Suez Canal, have raised questions among scientists and experts about its viability. Whether the Nicaragua Canal is really feasible for international shipping, given its high marine pollution risks, requires the further study. This paper discusses and analyses the feasibility of the Nicaragua Canal in the context of its environmental impact and value as a shipping service. This paper aims to provide an important information reference to inform strategic decision-making among policymakers and stakeholders. Our research results indicate that the environmental complexity, economic costs and safety risks of building a new transoceanic canal are simply too high to justify the project. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Assessment of periapical health, quality of root canal filling, and ...

    African Journals Online (AJOL)

    Sixty three teeth were found to have short root canal fillings, whereas 74 teeth had adequate root canal fillings, and the remaining 10 teeth had over extended root canal filling. A significant correlation was observed between the length of root filling and apical periodontitis (P = 0,023). Inadequately dense root canal filling was ...

  1. Study on the transmission efficiency of curved neutron guide

    International Nuclear Information System (INIS)

    Wang Hongli; Zhang Li; Guo Liping; Yang Tonghua; Zhao Zhixiang

    2004-01-01

    Monte-Carlo simulation program NGT2002 is used to study the transmission efficiency of curved neutron guide from character wavelength, film reflectivity, film material, geometry adjustment error, gap between guides and guide fabricate error, the authors get the transmission efficiency curves of the Ni, supper mirror curved neutron guides, also we have a discuss of how to choose the curved neutron guide's character wavelength. By the simulation results, the authors determine the proper film reflectivity value, guide horizontal geometry adjustment error range, optimized gap value between guide elements and guide width fabricate geometry error range. (authors)

  2. Endodontic management of a permanent mandibular first molar with six canals

    Directory of Open Access Journals (Sweden)

    Mohammad Ahmad Alenezi

    2016-01-01

    Full Text Available An excellent knowledge of root canal anatomy of teeth is a golden standard for the successful clinical outcome of root canal therapy. Several anatomic variations may occur in a permanent mandibular first molar. Usually, three to four root canals are found, but six to eight canals have been reported. A 22-year-old Bangladeshi woman was referred for endodontic treatment of mandibular right first molar. Rigorous clinical examination revealed the presence of three canals in mesial root and three canals in distal root as well. The dentists should expect any variation in root canal system and use the diagnostic tools to manage the cases.

  3. MRI diagnosis of intraspinal dermoid ruptured into central spinal canal

    International Nuclear Information System (INIS)

    Zhang Yong; Cheng Jingliang; Wang Juan; Li Huali; Ren Cuiping; Zhang Yan; Gao Xuemei

    2009-01-01

    Objective: To evaluate the appearances of intraspinal dermoid ruptured into the central spinal canal, as well as the MRI diagnosis and differential diagnosis. Methods: Eleven cases of intraspinal dermoid ruptured into the central spinal canal were reviewed. Six cases underwent whole spine MRI scan, 2 cases with thoracic and lumbar spine MRI, as well as 3 cases only with lumbar spine MRI. Results: Free fat droplets within spinal cord central canal demonstrated high signal intensity on T 1 WI, slight declined signal intensity on T 2 WI, and extremely low signal on fat suppression sequence. Of the 11 cases, 2 cases broke into neighboring central spinal canal of the dermoid, 3 cases scattered within thoracic spinal cord central canal, 4 cases discontinuously distributed in the whole spinal cord central canal, 2 cases showed continuous distribution. Conclusion: Intraspinal dermoid ruptured in the central spinal canal had specific appearance on MRI, when a dermoid tumor is suspected, MRI of the entire spine were recommended to detect possible leakage of' fat within central spinal canal. (authors)

  4. Canalization and control in automata networks: body segmentation in Drosophila melanogaster.

    Directory of Open Access Journals (Sweden)

    Manuel Marques-Pita

    Full Text Available We present schema redescription as a methodology to characterize canalization in automata networks used to model biochemical regulation and signalling. In our formulation, canalization becomes synonymous with redundancy present in the logic of automata. This results in straightforward measures to quantify canalization in an automaton (micro-level, which is in turn integrated into a highly scalable framework to characterize the collective dynamics of large-scale automata networks (macro-level. This way, our approach provides a method to link micro- to macro-level dynamics--a crux of complexity. Several new results ensue from this methodology: uncovering of dynamical modularity (modules in the dynamics rather than in the structure of networks, identification of minimal conditions and critical nodes to control the convergence to attractors, simulation of dynamical behaviour from incomplete information about initial conditions, and measures of macro-level canalization and robustness to perturbations. We exemplify our methodology with a well-known model of the intra- and inter cellular genetic regulation of body segmentation in Drosophila melanogaster. We use this model to show that our analysis does not contradict any previous findings. But we also obtain new knowledge about its behaviour: a better understanding of the size of its wild-type attractor basin (larger than previously thought, the identification of novel minimal conditions and critical nodes that control wild-type behaviour, and the resilience of these to stochastic interventions. Our methodology is applicable to any complex network that can be modelled using automata, but we focus on biochemical regulation and signalling, towards a better understanding of the (decentralized control that orchestrates cellular activity--with the ultimate goal of explaining how do cells and tissues 'compute'.

  5. Canalization and control in automata networks: body segmentation in Drosophila melanogaster.

    Science.gov (United States)

    Marques-Pita, Manuel; Rocha, Luis M

    2013-01-01

    We present schema redescription as a methodology to characterize canalization in automata networks used to model biochemical regulation and signalling. In our formulation, canalization becomes synonymous with redundancy present in the logic of automata. This results in straightforward measures to quantify canalization in an automaton (micro-level), which is in turn integrated into a highly scalable framework to characterize the collective dynamics of large-scale automata networks (macro-level). This way, our approach provides a method to link micro- to macro-level dynamics--a crux of complexity. Several new results ensue from this methodology: uncovering of dynamical modularity (modules in the dynamics rather than in the structure of networks), identification of minimal conditions and critical nodes to control the convergence to attractors, simulation of dynamical behaviour from incomplete information about initial conditions, and measures of macro-level canalization and robustness to perturbations. We exemplify our methodology with a well-known model of the intra- and inter cellular genetic regulation of body segmentation in Drosophila melanogaster. We use this model to show that our analysis does not contradict any previous findings. But we also obtain new knowledge about its behaviour: a better understanding of the size of its wild-type attractor basin (larger than previously thought), the identification of novel minimal conditions and critical nodes that control wild-type behaviour, and the resilience of these to stochastic interventions. Our methodology is applicable to any complex network that can be modelled using automata, but we focus on biochemical regulation and signalling, towards a better understanding of the (decentralized) control that orchestrates cellular activity--with the ultimate goal of explaining how do cells and tissues 'compute'.

  6. Numerical Simulation of the Vortex-Induced Vibration of A Curved Flexible Riser in Shear Flow

    Science.gov (United States)

    Zhu, Hong-jun; Lin, Peng-zhi

    2018-06-01

    A series of fully three-dimensional (3D) numerical simulations of flow past a free-to-oscillate curved flexible riser in shear flow were conducted at Reynolds number of 185-1015. The numerical results obtained by the two-way fluid-structure interaction (FSI) simulations are in good agreement with the experimental results reported in the earlier study. It is further found that the frequency transition is out of phase not only in the inline (IL) and crossflow (CF) directions but also along the span direction. The mode competition leads to the non-zero nodes of the rootmean- square (RMS) amplitude and the relatively chaotic trajectories. The fluid-structure interaction is to some extent reflected by the transverse velocity of the ambient fluid, which reaches the maximum value when the riser reaches the equilibrium position. Moreover, the local maximum transverse velocities occur at the peak CF amplitudes, and the values are relatively large when the vibration is in the resonance regions. The 3D vortex columns are shed nearly parallel to the axis of the curved flexible riser. As the local Reynolds number increases from 0 at the bottom of the riser to the maximum value at the top, the wake undergoes a transition from a two-dimensional structure to a 3D one. More irregular small-scale vortices appeared at the wake region of the riser, undergoing large amplitude responses.

  7. Three root canals in the maxillary second premolar

    Directory of Open Access Journals (Sweden)

    de Almeida-Gomes Fabio

    2009-01-01

    Full Text Available In this study, we report an endodontic treatment of the maxillary second premolar with three root canals and distinct foramens. The possibility of three root canals in this tooth is quite small; however, it must be taken into account in clinical and radiographic evaluation during endodontic treatment. Many times, their presence is noticed only after canal treatment due to continuing post-operative discomfort.

  8. The crazy project – Canal Istanbul

    Directory of Open Access Journals (Sweden)

    Seda Kundak

    2011-10-01

    Full Text Available It was late April 2011 when “the Crazy Project - Canal Istanbul” was proposed by the Prime Minister of Turkey, during his election campaign.  Although the idea of an artificial canal is not new, since it is initiated without any consensus between the people and institutions in Istanbul, the project immediately set a large number of debates. These vary from the legitimacy of decentralization of governance, to potential impacts of the canal on international politics, economy, environment and urban life.  Regarding past infrastructure projects in Istanbul, such large scale investments have caused extensive acceleration in construction sector in one hand and social and economic shifts on the other.  In this paper, the Canal Istanbul Project is evaluated according to basic motivations and claims of the PM, multi-perspective view through challenges and limitation that the project is likely to face with and speculations on implementation approach. The final discussion on the project is based on benefits/losses of Istanbul once the project will be implemented.

  9. Non-destructive, preclinical evaluation of root canal anatomy of human teeth with flat-panel detector volume CT (FD-VCT); Zerstoerungsfreie praeklinische Evaluation der Wurzelkanalanatomie menschlicher Zaehne mittels Flaechendetektor-Volumen-CT (FD-VCT)

    Energy Technology Data Exchange (ETDEWEB)

    Heidrich, G.; Hassepass, F.; Dullin, C.; Grabbe, E. [Universitaetsklinikum Goettingen, Abt. Diagnostische Radiologie (Germany); Attin, T.; Hannig, C. [Universitaetsklinikum Goettingen, Abt. fuer Zahnerhaltung, Praeventive Zahnheilkunde und Paradontologie (Germany)

    2005-12-15

    Purpose: Successful endodontic diagnostics and therapy call for adequate depiction of the root canal anatomy with multimodal diagnostic imaging. The aim of the present study is to evaluate visualization of the endodont with flat-panel detector volume CT (FD-VCT). Materials and methods: 13 human teeth were examined with the prototype of a FD-VCT. After data acquisition and generation of volume data sets in volume rendering technology (VRT), the findings obtained were compared to conventional X-rays and cross-section preparations of the teeth. Results: The anatomical structures of the endodont such as root canals, side canals and communications between different root canals as well as dentricles could be detected precisely with FD-VCT. The length of curved root canals was also determined accurately. The spatial resolution of the system is around 140 {mu}m. Only around 73% of the main root canals detected with FD-VCT and 87% of the roots could be visualized with conventional dental X-rays. None of the side canals, shown with FD-VCT, was detectable on conventional X-rays. In all cases the enamel and dentin of the teeth could be well delineated. No differences in image quality could be discerned between stored and freshly extracted teeth, or between primary and adult teeth. (orig.)

  10. Perfluoroalkyl substances in waters along the Grand Canal, China.

    Science.gov (United States)

    Piao, H T; Jiao, X C; Gai, N; Chen, S; Lu, G H; Yin, X C; Yamazaki, E; Yamashita, N; Tan, K Y; Yang, Y L; Pan, J

    2017-07-01

    The Grand Canal, also known as the Beijing-Hangzhou Grand Canal, is a UNESCO World Heritage Site and the longest canal in the world. It is an important trunk line of the South-to-North Water Diversion Project in China. The contamination status and spatial distributions of perfluoroalky substances (PFASs) in waters of the Grand Canal were investigated. The total concentrations of PFASs (∑PFASs) range from 7.8 ng/L to 218.0 ng/L, with high ∑PFASs occurring in the southern part of the Grand Canal which is located in a highly urbanized and economically developed region. The dominance of PFOA showed a decreasing trend toward north while shorter chain homologue proportions increased in the northern part of the Canal which mainly traverses underdeveloped and rural areas in Eastern China. Positive correlations were observed between ∑PFASs and the population density as well as GDP per capita. Intersection with large rivers may affect the contamination levels and composition of PFASs in the water of the Grand Canal near the intersection sites. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. A STUDY OF ROOT CANAL MORPHOLOGY OF Cebus apella TEETH ESTUDO ANATÔMICO DO CANAL RADICULAR DE DENTES DE Cebus apella

    Directory of Open Access Journals (Sweden)

    Priscilla Rocha Afonso

    2008-12-01

    Full Text Available Realizou-se um estudo anatômico em dentes do Cebus apella, para análise da anatomia interna do canal radicular dessa espécie, normatizando seu uso como modelo experimental. Utilizaram-se doze animais adultos. Após a remoção do tecido orgânico, os dentes foram removidos, seccionados e fotografados, sendo analisados com um estereomicroscópio. Os resultados mostraram que os dentes apresentaram características semelhantes às dos seres humanos, mas com algumas peculiaridades, tais como: a anatomia do canal radicular variou de oval para circular; nos caninos inferiores, os canais são semelhantes a um rim, o que reflete o contorno externo da raiz; nos molares superiores, os canais mesiobucal e distobucal são ovais, seguindo o contorno geral do dente. Os autores concluem que esta espécie pode ser utilizada como modelo em pesquisas odontológicas, principalmente em estudos do tratamento do sistema de canal radicular.

    PALAVRAS-CHAVES: Anatomia, dentes, Cebus apella. An anatomic study of Cebus apella root teeth was performed to analyze the internal anatomy of permanent dentition, normalizing its use as experimental model endodontic research. Twelve adult animals were used in this study. After the removal of the organic tissue, the all teeth were removed, sectioned, analyzed and photographed with a stereomicroscope. The results showed that the anatomy of root canal of this species are similar to human dental anatomy, considering the shape, pathway and number of canals, but with some peculiarities, such as: the root canal anatomy varied from oval to circular; in the lower canines, the canals are resembled a kidney, reflecting the outside contour of the root; in the upper molars, the mesiobuccal and distobuccal canals are oval, following the general contour of the tooth. The authors conclude that this primate can be applied as models for study of root canal treatment in human beings, in special the upper central and lateral incisors

  12. Computed tomography in lumbar canal stenosis

    International Nuclear Information System (INIS)

    Ohta, Shu; Baba, Itsushi; Ishida, Akihisa; Sumida, Tadayuki; Sasaki, Seishu

    1984-01-01

    Preoperative CT was done in 39 patients with lumbar canal stenosis. Marked symmetrical narrowing of the whole vertebral canal was seen in the group with nervous symptoms in the cauda equina. Deformed bilateral intervertebral joints were seen in the group with both nervous symptoms in the cauda equina and radicular sciatica. The lateral recess on the affected side was markedly narrowed by the projection of the upper and lower joints and herniation. In the group with radicular sciatica, the vertebral canal itself was not so narrowed, but the unilateral intervertebral joint was extremely deformed, causing a narrowing of the lateral recess. There were large differences in the angle of the left and right intervertebral joints. (Namekawa, K)

  13. Canal switch after canalith repositioning procedure for benign paroxysmal positional vertigo.

    Science.gov (United States)

    Lin, Giant C; Basura, Gregory J; Wong, Hiu Tung; Heidenreich, Katherine D

    2012-09-01

    Canal switch is a complication following canalith repositioning procedure (CRP) for posterior canal benign paroxysmal positional vertigo (BPPV). Instead of being returned to the utricle, the loose otoconia migrate into the superior or horizontal semicircular canal. Patients remain symptomatic, and treatment can be ineffective unless the switch is recognized and additional repositioning maneuvers directed toward the appropriate semicircular canal are performed. This report provides the first videographic documentation of canal switch involving conversion of unilateral posterior semicircular canal BPPV to geotropic horizontal canalithiasis. Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.

  14. C-shaped root canal in a maxillary first molar: a case report.

    Science.gov (United States)

    Yilmaz, Z; Tuncel, B; Serper, A; Calt, S

    2006-02-01

    This case report presents an unusual C-shaped root canal system in a maxillary first molar tooth. Although C-shaped root canals are most frequently seen in the mandibular second molar, they may also appear in maxillary molars. A literature search revealed only a few case reports of C-shaped root canal systems in maxillary molars. The present case describes a C-shaped canal in the buccal root of a maxillary first molar. The endodontic access cavity displayed two canal orifices, one leading to the canal system in the buccal root, the other into the palatal root canal system. In the buccal root, what appeared to be the mesial and distal canals joined to form a single C-shaped canal. --Careful examination of radiographs and the internal anatomy of teeth is essential.-- The location and morphology of root canals should be identified at high magnification under the microscope.

  15. ROBUST DECLINE CURVE ANALYSIS

    Directory of Open Access Journals (Sweden)

    Sutawanir Darwis

    2012-05-01

    Full Text Available Empirical decline curve analysis of oil production data gives reasonable answer in hyperbolic type curves situations; however the methodology has limitations in fitting real historical production data in present of unusual observations due to the effect of the treatment to the well in order to increase production capacity. The development ofrobust least squares offers new possibilities in better fitting production data using declinecurve analysis by down weighting the unusual observations. This paper proposes a robustleast squares fitting lmRobMM approach to estimate the decline rate of daily production data and compares the results with reservoir simulation results. For case study, we usethe oil production data at TBA Field West Java. The results demonstrated that theapproach is suitable for decline curve fitting and offers a new insight in decline curve analysis in the present of unusual observations.

  16. Fractional-order mathematical model of an irrigation main canal pool

    Directory of Open Access Journals (Sweden)

    Shlomi N. Calderon-Valdez

    2015-09-01

    Full Text Available In this paper a fractional order model for an irrigation main canal is proposed. It is based on the experiments developed in a laboratory prototype of a hydraulic canal and the application of a direct system identification methodology. The hydraulic processes that take place in this canal are equivalent to those that occur in real main irrigation canals and the results obtained here can therefore be easily extended to real canals. The accuracy of the proposed fractional order model is compared by deriving two other integer-order models of the canal of a complexity similar to that proposed here. The parameters of these three mathematical models have been identified by minimizing the Integral Square Error (ISE performance index existing between the models and the real-time experimental data obtained from the canal prototype. A comparison of the performances of these three models shows that the fractional-order model has the lowest error and therefore the higher accuracy. Experiments showed that our model outperformed the accuracy of the integer-order models by about 25%, which is a significant improvement as regards to capturing the canal dynamics.

  17. About ecological aspects of "Eurasia" canal construction

    Directory of Open Access Journals (Sweden)

    G. M. Abdurakhmanov

    2010-01-01

    Full Text Available Ecological aspects of "Eurasia" canal construction are considered here. The fact that can negatively affect natural area preservation (preserves, reserves, located in Kumo-Manych depression, along where the canal construction will take place, is shown in this article.

  18. Influence of root canal sealer on the radiographic appearance of filling voids in maxillary single-rooted teeth.

    Science.gov (United States)

    Bodanezi, Augusto; Munhoz, Etiene Andrade; Capelozza, Ana Lúcia Álvares; Bernardineli, Norberti; Moraes, Ivaldo Gomes de; Garcia, Roberto Brandão; Bramante, Clovis Monteiro

    2012-01-01

    This study compared the influence of three epoxy resin-based sealers with distinct radiopacities on the observers' ability to detect root canal filling voids during radiographic analysis. The root canals of 48 extracted maxillary canines were prepared and divided into three groups. Each group was laterally condensed with one sealer (AH Plus®, Acroseal® or a non-radiopaque sealer), and a longitudinal void was simulated in half of the specimens from each group (n=8). Buccolingual radiographs were obtained and randomly interpreted for voids by a radiologist and an endodontist in a blinded fashion. Teeth were cut and inspected under a microscope to confirm the position of void. Differences in sensitivity and specificity between groups and examiners were compared using the Fisher's Exact and McNemar tests, respectively (α=0.05). Significantly lower sensitivity levels (p<0.05) were observed in the coronal portion of fillings performed with both radiopaque sealers. Specificity values for Acroseal® were significantly higher (p<0.05) in the coronal and apical portions of fillings. The type of root canal sealer can affect the observers' ability to detect root canal filling voids during radiographic analysis of upper single-rooted teeth.

  19. Otolith and canal reflexes in human standing

    Science.gov (United States)

    Cathers, Ian; Day, Brian L; Fitzpatrick, Richard C

    2005-01-01

    We used galvanic vestibular stimulation (GVS) to identify human balance reflexes of the semicircular canals and otolith organs. The experiment used a model of vestibular signals arising from GVS modulation of the net signal from vestibular afferents. With the head upright, the model predicts that the GVS-evoked canal signal indicates lateral head rotation while the otolith signal indicates lateral tilt or acceleration. Both signify body sway transverse to the head. With the head bent forward, the model predicts that the canal signal indicates body spin about a vertical axis but the otolith signal still signifies lateral body motion. Thus, we compared electromyograms (EMG) in the leg muscles and body sway evoked by GVS when subjects stood with the head upright or bent forward. With the head upright, GVS evoked a large sway in the direction of the anodal electrode. This response was abolished with the head bent forward leaving only small, oppositely directed, transient responses at the start and end of the stimulus. With the head upright, GVS evoked short-latency (60–70 ms), followed by medium-latency (120 ms) EMG responses, of opposite polarity. Bending the head forward abolished the medium-latency but preserved the short-latency response. This is compatible with GVS evoking separate otolithic and canal reflexes, indicating that balance is controlled by independent canal and otolith reflexes, probably through different pathways. We propose that the short-latency reflex and small transient sway are driven by the otolith organs and the medium-latency response and the large sway are driven by the semicircular canals. PMID:15618274

  20. ROOT CANAL IRRIGANTS AND IRRIGATION TECHNIQUES: A REVIEW

    OpenAIRE

    Aniketh; Mohamed; Geeta; Nandakishore; Gourav Kumar; Patrick Timothy; Jayson Mathew; Sahle Abdul

    2015-01-01

    Root canal irrigation is not much emphasised in endodontic therapy. Most articles discussed are on root canal shaping and obturation not much emphasis is given for irrigation. There are many irrigation solutions which are introduced into market. The primary objective of root canal therapy is the ret ention of the pulpless or pulpally involved tooth with its associated periapical tissues in a healthy state. Achievement of this objective requires that the pulpal spaces and con...

  1. Cervical shaping in curved root canals: comparison of the efficiency of two endodontic instruments

    Directory of Open Access Journals (Sweden)

    Busquim Sandra Soares Kühne

    2002-01-01

    Full Text Available The aim of this study was to determine the removal of dentin produced by number 25 (0.08 Flare files (Quantec Flare Series, Analytic Endodontics, Glendora, California, USA and number 1 e 2 Gates-Glidden burs (Dentsply - Maillefer, Ballaigues, Switzerland, in the mesio-buccal and mesio-lingual root canals, respectively, of extracted human permanent inferior molars, by means of measuring the width of dentinal walls prior and after instrumentation. The obtained values were compared. Due to the multiple analyses of data, a nonparametric test was used, and the Kruskal-Wallis test was chosen. There was no significant difference between the instruments as to the removal of dentin in the 1st and 2nd millimeters. However, when comparing the performances of the instruments in the 3rd millimeter, Flare files promoted a greater removal than Gates-Glidden drills (p > 0.05. The analysis revealed no significant differences as to mesial wear, which demonstrates the similar behavior of both instruments. Gates-Glidden drills produced an expressive mesial detour in the 2nd and 3rd millimeters, which was detected trough a statistically significant difference in the wear of this region (p > 0.05. There was no statistically significant difference between mesial and lateral wear when Flare instruments were employed.

  2. Cervical shaping in curved root canals: comparison of the efficiency of two endodontic instruments.

    Science.gov (United States)

    Busquim, Sandra Soares Kühne; dos Santos, Marcelo

    2002-01-01

    The aim of this study was to determine the removal of dentin produced by number 25 (0.08) Flare files (Quantec Flare Series, Analytic Endodontics, Glendora, California, USA) and number 1 e 2 Gates-Glidden burs (Dentsply - Maillefer, Ballaigues, Switzerland), in the mesio-buccal and mesio-lingual root canals, respectively, of extracted human permanent inferior molars, by means of measuring the width of dentinal walls prior and after instrumentation. The obtained values were compared. Due to the multiple analyses of data, a nonparametric test was used, and the Kruskal-Wallis test was chosen. There was no significant difference between the instruments as to the removal of dentin in the 1st and 2nd millimeters. However, when comparing the performances of the instruments in the 3rd millimeter, Flare files promoted a greater removal than Gates-Glidden drills (p > 0.05). The analysis revealed no significant differences as to mesial wear, which demonstrates the similar behavior of both instruments. Gates-Glidden drills produced an expressive mesial detour in the 2nd and 3rd millimeters, which was detected trough a statistically significant difference in the wear of this region (p > 0.05). There was no statistically significant difference between mesial and lateral wear when Flare instruments were employed.

  3. Maxillary second molar with four roots and five canals

    Directory of Open Access Journals (Sweden)

    Xinjia Sha

    2018-06-01

    Full Text Available In this case report, we present a maxillary second molar variant, which had two palatal roots with two canals and two buccal roots with three canals, including a second mesiobuccal canal. A 44-year-old female patient complained about a tooth crown fracture and severe pain in her right maxillary second molar. A clinical intraoral inspection and radiography were carried out on the tooth, and a diagnosis of chronic apical periodontitis was made. Four roots (two buccal and two palatal and five canals (three buccal and two palatal were found. The anatomical variation of the tooth was further confirmed by cone-beam computed tomography, a cone-fit procedure, and a radiograph with a shifted projection angle. Root-canal treatment was performed under an endodontic microscope.

  4. Root canal treatment and special needs patients.

    Science.gov (United States)

    Yap, E; Parashos, P; Borromeo, G L

    2015-04-01

    To identify current trends of root canal treatment for patients with special needs. A postal questionnaire was sent to General Dentists in Victoria, Australia and Endodontists and Special Needs Dentists across Australia to determine the extent of root canal treatment performed on special needs patients. Over a four-month period, 1120 questionnaires were distributed with an overall response rate of 63.9% (n = 716). Response rates were 63.2% (n = 655), 68.5% (n = 50) and 100.0% (n = 11) amongst General Dentists, Endodontists and Special Needs Dentists, respectively. Endodontists (95.7%) and Special Needs Dentists (100.0%) performed significantly more root canal treatment on adult patients with special needs compared with 51.2% of General Dentists, (P special needs patients compared with only 29.7% of General Dentists (P special needs patients was more likely to be carried out by specialist dental practitioners who were more likely to utilize a pharmacological approach for behaviour guidance and to perform single-visit root canal treatment compared with General Dentists. A multidisciplinary approach for special needs patients who require root canal treatment provides an opportunity for these patients to retain their dentition. © 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  5. An endodontic management of mandibular third molar with five root canals

    OpenAIRE

    Dakshita Joy Sinha; Ashish Amit Sinha

    2014-01-01

    The existence of several anatomical variations in the root canal system may contribute to failure of the root canal therapy. The planning and performing of endodontic therapy requires knowledge of the internal dental morphology. This paper reports the case of a left mandibular third molar that presented with five root canals; a case of unusual root canal morphology so as to demonstrate the anatomic variations in mandibular third molars. Root canal therapy and case management are described. Th...

  6. The Effect of Canal Contamination with Saliva on Apical Sealing

    Directory of Open Access Journals (Sweden)

    S Sabaghi

    2014-08-01

    Full Text Available Introduction: Root canal obturation aims at sealing the root canal system to prevent re-contamination of canal and periapical space. Presence of moisture in canal before obturation may posit a negative effect on the quality of canal sealing. Therefore, this study was conducted to investigate the effect of canal contamination with saliva on apical microleakage. Methods: In this laboratory study, 58 human uni-root teeth were cleaned and shaped for obturation with gutta percha and sealer AH26. In the case group, specimens were contaminated with human saliva immediately before obturation, whereas the teeth in the control group were kept dry. All canals were filled by lateral condensation technique. Moreover, the teeth were placed in methylene blue dye for 3 days. Dye penetration was measured using a stereomicrosope. As a matter of fact, the study data were analyzed via utilizing t-test. Results: A significant difference was found between the two groups in regard with the apical leakage(P<0.001. The microleakage mean of dye in the dry group was 3/48mm, whereas it was 6/36mm in the saliva contaminated group. Conclusion: The study findings revealed that complete drying of canal can improve apical sealing.

  7. Evaluation of surface preparation and maintenance of canal curvature following instrumentation with hand 'K' file and three different Ni-Ti rotary systems: A radiographic and SEM study.

    Science.gov (United States)

    Bhatti, Namrata; Sroa, Renu; Sikri, Vimal K

    2010-04-01

    To determine the shaping ability and cleaning efficiency of hand K-flexofiles, ProTaper, LightSpeed and Mtwo instruments during the preparation of curved root canals in extracted human teeth. A total of 120 root canals of mandibular and maxillary molars with curvature more than 20° were divided into four groups of 30 each. In group A, canals were prepared using hand K-flexofiles following the crown down technique. In group B LightSpeed, in group C ProTaper, and in group D Mtwo rotary instruments were used to prepare the root canals. Using pre- and post-instrumentation radiographs, straightening of the canal curvature was determined with Corel Draw 9.0 software tools. The amount of debris and smear layer were quantified at three different areas (coronal, middle, and apical thirds) of root canal using SEM. The collected data were analyzed statistically using Student's paired 't' test. The mean change in curvature for hand K-files was 7.71°, for ProTaper files 6.03°, for Mtwo 5.43°, and for LightSpeed instruments were found to be 4.57°. The percentage change in the curvature for all the four groups was statistically highly significant (PProTaper (65.48%) followed by Mtwo (66.22%), LightSpeed (71.67%) and the maximum with hand K-files (74.16%). However, the difference in mean leftover debris between ProTaper and Mtwo was not significant. ProTaper and Mtwo resulted in good cleaning, and LightSpeed maintained the original canal curvature better than the ProTaper, Mtwo, or Hand K-files.

  8. An endodontic management of mandibular third molar with five root canals

    Directory of Open Access Journals (Sweden)

    Dakshita Joy Sinha

    2014-01-01

    Full Text Available The existence of several anatomical variations in the root canal system may contribute to failure of the root canal therapy. The planning and performing of endodontic therapy requires knowledge of the internal dental morphology. This paper reports the case of a left mandibular third molar that presented with five root canals; a case of unusual root canal morphology so as to demonstrate the anatomic variations in mandibular third molars. Root canal therapy and case management are described. This report highlights the importance of looking for additional roots and root canals so as to enable clinicians to treat a case successfully, which might have ended in failure.

  9. Optimizing the chemical aspect of root canal irrigation

    OpenAIRE

    de Macedo, R.G.

    2013-01-01

    Root canal treatment is aimed at the removal of inflamed and infected tissue present in the root canal system. It will prevent the entrance of new microorganisms or nutrients in order to maintain or create a healthy environment around the root. There is sufficient evidence that shows that traditional endodontic therapy cannot make the root canal system completely free of bacteria. Moreover, it may not always result in complete healing of apical periodontitis, highlighting the need of optimizi...

  10. Magnetic resonance imaging of the internal auditory canal

    International Nuclear Information System (INIS)

    Daniels, D.L.; Herfkins, R.; Koehler, P.R.; Millen, S.J.; Shaffer, K.A.; Williams, A.L.; Haughton, V.M.

    1984-01-01

    Three patients with exclusively or predominantly intracanalicular neuromas and 5 with presumably normal internal auditory canals were examined with prototype 1.4- or 1.5-tesla magnetic resonance (MR) scanners. MR images showed the 7th and 8th cranial nerves in the internal auditory canal. The intracanalicular neuromas had larger diameter and slightly greater signal strength than the nerves. Early results suggest that minimal enlargement of the nerves can be detected even in the internal auditory canal

  11. Roles of the combined irrigation, drainage, and storage of the canal network in improving water reuse in the irrigation districts along the lower Yellow River, China

    Science.gov (United States)

    Liu, Lei; Luo, Yi; He, Chansheng; Lai, Jianbin; Li, Xiubin

    2010-09-01

    SummaryThe commonly used irrigation system in the irrigation districts (with a combined irrigation area of 3.334 × 10 6 ha) along the lower Yellow River of China is canal network. It delivers water from the Yellow River to the fields, collects surface runoff and drainage from cropland, and stores both of them for subsequent irrigation uses. This paper developed a new combined irrigation, drainage, and storage (CIDS) module for the SWAT2000 model, simulated the multiple roles of the CIDS canal system, and estimated its performance in improving water reuse in the irrigation districts under different irrigation and water diversion scenarios. The simulation results show that the annual evapotranspiration (ET) of the double-cropping winter wheat and summer maize was the highest under the full irrigation scenario (automatic irrigation), and the lowest under the no irrigation scenario. It varied between these two values when different irrigation schedules were adopted. Precipitation could only meet the water requirement of the double-cropping system by 62-96% on an annual basis; that of the winter wheat by 32-36%, summer maize by 92-123%, and cotton by 87-98% on a seasonal basis. Hence, effective irrigation management for winter wheat is critical to ensure high wheat yield in the study area. Runoff generation was closely related to precipitation and influenced by irrigation. The highest and lowest annual runoff accounted for 19% and 11% of the annual precipitation under the full irrigation and no irrigation scenarios, respectively. Nearly 70% of the annual runoff occurred during months of July and August due to the concentrated precipitation in these 2 months. The CIDS canals play an important role in delivering the diversion water from the Yellow River, intercepting the surface runoff and drainage from cropland (inflow of the CIDS canal) and recharging the shallow aquifer for later use. Roughly 14-26% of the simulated total flow in the CIDS canal system recharged

  12. Maxillary First Molars with 2 Distobuccal Canals: A Case Series.

    Science.gov (United States)

    Fogel, Howard M; Cunha, Rodrigo Sanches

    2017-11-01

    An appreciation of the anatomic complexity of the root canal system is essential at every step of endodontic treatment. Endodontic treatment of teeth with unusual root canal anatomy presents a unique challenge. Eight patients underwent nonsurgical root canal treatment of 3-rooted maxillary first molars in a specialty endodontic private practice. Four cases of Weine type II and 4 cases of Weine type III canal configurations in the distobuccal root of maxillary first molars were presented.This article highlighted an uncommon anatomic variation of 2 canals in the distobuccal root of the maxillary first molar. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  13. Testing the validity of stock-recruitment curve fits

    International Nuclear Information System (INIS)

    Christensen, S.W.; Goodyear, C.P.

    1988-01-01

    The utilities relied heavily on the Ricker stock-recruitment model as the basis for quantifying biological compensation in the Hudson River power case. They presented many fits of the Ricker model to data derived from striped bass catch and effort records compiled by the National Marine Fisheries Service. Based on this curve-fitting exercise, a value of 4 was chosen for the parameter alpha in the Ricker model, and this value was used to derive the utilities' estimates of the long-term impact of power plants on striped bass populations. A technique was developed and applied to address a single fundamental question: if the Ricker model were applicable to the Hudson River striped bass population, could the estimates of alpha from the curve-fitting exercise be considered reliable. The technique involved constructing a simulation model that incorporated the essential biological features of the population and simulated the characteristics of the available actual catch-per-unit-effort data through time. The ability or failure to retrieve the known parameter values underlying the simulation model via the curve-fitting exercise was a direct test of the reliability of the results of fitting stock-recruitment curves to the real data. The results demonstrated that estimates of alpha from the curve-fitting exercise were not reliable. The simulation-modeling technique provides an effective way to identify whether or not particular data are appropriate for use in fitting such models. 39 refs., 2 figs., 3 tabs

  14. Assessment of bifid and trified mandicular canals using cone beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Rashsyren, Oyuntugs [Dept. of Oral and Maxillofacial Radiology, School of Dentistry, Mongolian National University Medical Science, Ulaanbaatar (United States); Choi, Jin Woo; Han, Won Jeong; Kim Eun Kyung [Dept. of Oral and Maxillofacial Radiology, Dankook University College of Dentistry, Cheonan (Korea, Republic of)

    2014-09-15

    To investigate the prevalence of bifid and trifid mandibular canals using cone-beam computed tomography (CBCT) images, and to measure their length, diameter, and angle. CBCT images of 500 patients, involving 755 hemi-mandibles, were used for this study. The presence and type of bifid mandibular canal was evaluated according to a modified classification of Naitoh et al. Prevalence rates were determined according to age group, gender, and type. Further, their diameter, length, and angles were measured using PACSPLUS Viewer and ImageJ 1.46r. Statistical analysis with chi-squared and analysis of variance (ANOVA) tests was performed. Bifid and trifid mandibular canals were found in 22.6% of the 500 patients and 16.2% of the 755 sides. There was no significant difference between genders and among age groups. The retromolar canal type accounted for 71.3% of the identified canals; the dental canal type, 18.8%; the forward canal type, 4.1%; and the trifid canal type, 5.8%. Interestingly, seven cases of the trifid canal type, which has been rarely reported, were observed. The mean diameter of the bifid and trifid mandibular canals was 2.2 mm and that of the main mandibular canal was 4.3 mm. Their mean length was 16.9 mm; the mean superior angle was 149.2 degrees, and the mean inferior angle was 37.7 degrees. Bifid and trifid mandibular canals in the Korean population were observed at a relatively high rate through a CBCT evaluation, and the most common type was the retromolar canal. CBCT is suggested for a detailed evaluation of bifid and trifid mandibular canals before mandibular surgery.

  15. A study of incisive canal using a cone beam computed tomography

    International Nuclear Information System (INIS)

    Kim, Gyu Tae; Hwang, Eui Hwan; Lee, Sang Rae

    2004-01-01

    To investigate the anatomical structure of the incisive canal radiographically by a cone beam computed tomography. 38 persons (male 26, female 12) were chosen to take images of maxillary anterior region in dental CT mode using a cone beam computed tomography. The tube voltage were 65, 67, and 70 kVp, the tube current was 7 mA, and the exposure time was 13.3 seconds. The FH plane of each person was parallel to the floor. The images were analysed on the CRT display. The mean length of incisive canal was 15.87 mm ± 2.92. The mean diameter at the side of palate and nasal fossa were 3.49 mm ± 0.76 and 3.89 mm ± 1.06, respectively. In the cross-sectional shape of incisive canal, 50% were round, 34.2% were ovoid, and 15.8% were lobulated. 87% of incisive canal at the side of nasal fossa have one canal, 10.4% have two canals, and 2.6% have three canals, but these canals were merged into one canal in the middle portion of palate. The mean angles of the long axis of incisive canal and central incisor to the FH plane were 110.3 ± 6.96 and 117.45 ± 7.41, respectively. The angles of the long axis of incisive canal and central incisor to the FH plane were least correlated (r 0.258). This experiment suggests that a cone beam computed radiography will be helpful in surgery or implantation on the maxillary incisive area.

  16. A study of incisive canal using a cone beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gyu Tae; Hwang, Eui Hwan; Lee, Sang Rae [Kyunghee University College of Medicine, Seoul (Korea, Republic of)

    2004-03-15

    To investigate the anatomical structure of the incisive canal radiographically by a cone beam computed tomography. 38 persons (male 26, female 12) were chosen to take images of maxillary anterior region in dental CT mode using a cone beam computed tomography. The tube voltage were 65, 67, and 70 kVp, the tube current was 7 mA, and the exposure time was 13.3 seconds. The FH plane of each person was parallel to the floor. The images were analysed on the CRT display. The mean length of incisive canal was 15.87 mm {+-} 2.92. The mean diameter at the side of palate and nasal fossa were 3.49 mm {+-} 0.76 and 3.89 mm {+-} 1.06, respectively. In the cross-sectional shape of incisive canal, 50% were round, 34.2% were ovoid, and 15.8% were lobulated. 87% of incisive canal at the side of nasal fossa have one canal, 10.4% have two canals, and 2.6% have three canals, but these canals were merged into one canal in the middle portion of palate. The mean angles of the long axis of incisive canal and central incisor to the FH plane were 110.3 {+-} 6.96 and 117.45 {+-} 7.41, respectively. The angles of the long axis of incisive canal and central incisor to the FH plane were least correlated (r 0.258). This experiment suggests that a cone beam computed radiography will be helpful in surgery or implantation on the maxillary incisive area.

  17. Bilateral duplication of the internal auditory canal

    International Nuclear Information System (INIS)

    Weon, Young Cheol; Kim, Jae Hyoung; Choi, Sung Kyu; Koo, Ja-Won

    2007-01-01

    Duplication of the internal auditory canal is an extremely rare temporal bone anomaly that is believed to result from aplasia or hypoplasia of the vestibulocochlear nerve. We report bilateral duplication of the internal auditory canal in a 28-month-old boy with developmental delay and sensorineural hearing loss. (orig.)

  18. 33 CFR 117.769 - Black Rock Canal.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Black Rock Canal. 117.769 Section 117.769 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New York § 117.769 Black Rock Canal. The draws of the...

  19. Laser scanning dental probe for endodontic root canal treatment

    Science.gov (United States)

    Blank, Molly A. B.; Friedrich, Michal; Hamilton, Jeffrey D.; Lee, Peggy; Berg, Joel; Seibel, Eric J.

    2011-03-01

    Complications that arise during endodontic procedures pose serious threats to the long-term integrity and health of the tooth. Potential complexities of root canals include residual pulpal tissue, cracks, mesial-buccal 2 and accessory canals. In the case of a failed root canal, a successful apicoectomy can be jeopardized by isthmuses, accessory canals, and root microfracture. Confirming diagnosis using a small imaging probe would allow proper treatment and prevent retreatment of endodontic procedures. An ultrathin and flexible laser scanning endoscope of 1.2 to 1.6mm outer diameter was used in vitro to image extracted teeth with varied root configurations. Teeth were opened using a conventional bur and high speed drill. Imaging within the opened access cavity clarified the location of the roots where canal filing would initiate. Although radiographs are commonly used to determine the root canal size, position, and shape, the limited 2D image perspective leaves ambiguity that could be clarified if used in conjunction with a direct visual imaging tool. Direct visualization may avoid difficulties in locating the root canal and reduce the number of radiographs needed. A transillumination imaging device with the separated illumination and light collection functions rendered cracks visible in the prepared teeth that were otherwise indiscernible using reflected visible light. Our work demonstrates that a small diameter endoscope with high spatial resolution may significantly increase the efficiency and success of endodontic procedures.

  20. Radiographic versus electronic root canal working length determination

    Directory of Open Access Journals (Sweden)

    Lumnije Kqiku

    2011-01-01

    Conclusions: The present ex vivo study showed that electronic root canal working length determination is not superior to radiographic methods. Both methods provided a good performance in determining the root canal working length.

  1. 46 CFR 69.7 - Vessels transiting the Panama and Suez Canals.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Vessels transiting the Panama and Suez Canals. 69.7... MEASUREMENT OF VESSELS MEASUREMENT OF VESSELS General § 69.7 Vessels transiting the Panama and Suez Canals. (a... Canal must be measured and certificated under the Arab Republic of Egypt Suez Canal Authority Rules of...

  2. Evaluation of root canal morphology of human mandibular incisors in Yazd

    Directory of Open Access Journals (Sweden)

    Tabrizi-zadeh M. Assistant Professor

    2003-06-01

    Full Text Available Statement of Problem: The main objective of endodontic therapy is chemomechanical cleansing of entire pulp cavity and its complete obturation with an inert material. During this procedure, the failure of detection and inadequate cleaning of a canal will result in failed endodontic therapy. Therefore, the dentist must have enough knowledge of root canal morphology to treat a tooth successfully."nAim: The aim of this study was to determine the number and type of root canals of mandibular incisor teeth."nMaterials and Methods: In order to do this in-vitro, descriptive study, 68 non-carious mandibular incisor teethj collected from different clinics in Yazd, were immersed in indian ink, decalcified and cleared."nResults: It was found that 55.9% of the teeth had two separate canals that in 5.5% of them, the canals"nmerged before' apical foramen. In 4.4% of these samples, two separate canals existed along the whole"nroot."nConclusion: Considering high percentage of two canals in lower mandibular incisors, during access preparation, more attempts in detection of the second canal, is emphasized.

  3. Prior-knowledge-based feedforward network simulation of true boiling point curve of crude oil.

    Science.gov (United States)

    Chen, C W; Chen, D Z

    2001-11-01

    Theoretical results and practical experience indicate that feedforward networks can approximate a wide class of functional relationships very well. This property is exploited in modeling chemical processes. Given finite and noisy training data, it is important to encode the prior knowledge in neural networks to improve the fit precision and the prediction ability of the model. In this paper, as to the three-layer feedforward networks and the monotonic constraint, the unconstrained method, Joerding's penalty function method, the interpolation method, and the constrained optimization method are analyzed first. Then two novel methods, the exponential weight method and the adaptive method, are proposed. These methods are applied in simulating the true boiling point curve of a crude oil with the condition of increasing monotonicity. The simulation experimental results show that the network models trained by the novel methods are good at approximating the actual process. Finally, all these methods are discussed and compared with each other.

  4. Prevalence of the middle mesial canal in non surgical root canal treated mandibular first and second molars in a local military population

    Science.gov (United States)

    2016-06-13

    or second mandibular molar), sex, and age. Materials and Methods Approximately 7, 000 dental records in paper chart format were reviewed at a...Army Post Graduate Dental School Douglas D. Lancaster, COL, DC 3 August 2016 Prevalence of the middle mesial canal in non-surgical root canal...Methods: 7000 dental records were reviewed for non-surgical root canals performed from October 1970 to October 2015. The data collected included

  5. Effects of canal enlargement and irrigation needle depth on the cleaning of the root canal system at 3 mm from the apex

    Directory of Open Access Journals (Sweden)

    Ho-Jin Moon

    2012-02-01

    Full Text Available Objectives The aim of this study was to test the hypothesis, that the effectiveness of irrigation in removing smear layer in the apical third of root canal system is dependent on the depth of placement of the irrigation needle into the root canal and the enlargement size of the canal. Materials and Methods Eighty sound human lower incisors were divided into eight groups according to the enlargement size (#25, #30, #35 and #40 and the needle penetration depth (3 mm from working length, WL-3 mm and 9 mm from working length, WL-9 mm. Each canal was enlarged to working length with Profile.06 Rotary Ni-Ti files and irrigated with 5.25% NaOCl. Then, each canal received a final irrigation with 3 mL of 3% EDTA for 4 min, followed by 5 mL of 5.25% NaOCl at different level (WL-3 mm and WL-9 mm from working length. Each specimen was prepared for the scanning electron microscope (SEM. Photographs of the 3mm area from the apical constriction of each canal with a magnification of ×250, ×500, ×1,000, ×2,500 were taken for the final evaluation. Results Removal of smear layer in WL-3 mm group showed a significantly different effect when the canal was enlarged to larger than #30. There was a significant difference in removing apical smear layer between the needle penetration depth of WL-3 mm and WL-9 mm. Conclusions Removal of smear layer from the apical portion of root canals was effectively accomplished with apical instrumentation to #35/40 06 taper file and 3 mm needle penetration from the working length.

  6. C-SHAPED CONFIGURATION OF THE ROOT CANAL SYSTEM – PROBLEMS AND SOLUTIONS.

    Directory of Open Access Journals (Sweden)

    Janet Kirilova

    2014-06-01

    Full Text Available Introduction: The patients with C-shaped configuration of the root canal system are definitely a problem in the everyday dental practice. The C-shaped configuration of the root canal can be seen in the mandibular and maxillary molars. The treatment of these teeth is very difficult. Purpose: To trace the treatment of clinical cases with C-shaped configuration of the root canal system. Material and methods: There are some different cases that are described with a C-shaped configuration of the root canal system with one, two, three and four separate root canals. Careful exploration of the floor of the pulp chamber, inspection with magnification, use of ultrasonic irrigation and a modified filling technique are of particular use. Results and Discussion: Clinical cases of a C-shaped pulp chamber and root canal system shows that this root canal aberration occurs in a wide variety and variability with a single root canal up to two, three and four separate root canals. The diameter of the root canal themselves also varies from very wide to such with a small diameter. Conclusions: Knowledge of the different anatomical variations will improve the endododntic practice of the general dental practitioners.

  7. Canal transportation and centering ability of protaper and self-adjusting file system in long oval canals: An ex-vivo cone-beam computed tomography analysis.

    Science.gov (United States)

    Shah, Dipali Yogesh; Wadekar, Swati Ishwara; Dadpe, Ashwini Manish; Jadhav, Ganesh Ranganath; Choudhary, Lalit Jayant; Kalra, Dheeraj Deepak

    2017-01-01

    The purpose of this study was to compare and evaluate the shaping ability of ProTaper (PT) and Self-Adjusting File (SAF) system using cone-beam computed tomography (CBCT) to assess their performance in oval-shaped root canals. Sixty-two mandibular premolars with single oval canals were divided into two experimental groups ( n = 31) according to the systems used: Group I - PT and Group II - SAF. Canals were evaluated before and after instrumentation using CBCT to assess centering ratio and canal transportation at three levels. Data were statistically analyzed using one-way analysis of variance, post hoc Tukey's test, and t -test. The SAF showed better centering ability and lesser canal transportation than the PT only in the buccolingual plane at 6 and 9 mm levels. The shaping ability of the PT was best in the apical third in both the planes. The SAF had statistically significant better centering and lesser canal transportation in the buccolingual as compared to the mesiodistal plane at the middle and coronal levels. The SAF produced significantly less transportation and remained centered than the PT at the middle and coronal levels in the buccolingual plane of oval canals. In the mesiodistal plane, the performance of both the systems was parallel.

  8. Report from the Panama Canal Stakeholder Working Group.

    Science.gov (United States)

    2013-03-01

    This project assists the Texas Department of Transportation (TxDOT) in assessing the potential impacts of the Panama Canal expansion on Texas ports and the landside transportation system. TxDOT formed a Panama Canal Stakeholder Working Group (PCSWG) ...

  9. Morphometric study of the lumbar spinal canal in the Korean population.

    Science.gov (United States)

    Lee, H M; Kim, N H; Kim, H J; Chung, I H

    1995-08-01

    The anatomic dimensions of the vertebral body and spinal canal of the lumbar spine were analyzed in Koreans. To determine the normal dimension of the lumbar spinal canal in Koreans, to determine whether there are any racial differences in the morphometry of the lumbar spinal canal, and to provide criteria for diagnosing spinal stenosis in the Far Eastern Asian. Some radiologic and anatomic studies have been conducted regarding the size of the lumbar spinal canal of whites and blacks in western and African countries. One-thousand-eight-hundred measurements were performed on the transverse and sagittal diameters of vertebral bodies and spinal canals using complete sets of 90 lumbar vertebrae. The mean mid-sagittal diameter of the lumbar spinal canal in the Korean population was less than that measured in white and African populations, but there was no significant differences between the Korean, white, and African populations regarding the transverse diameter of the lumbar spinal canal. The mid-sagittal diameter of the lumbar spinal canal is narrowest in the Far Eastern Asian population; the radiologic criteria of spinal stenosis should be reconsidered for these people.

  10. Root Canal Configuration of Mandibular First and Second Premolars in an Iranian Population

    Directory of Open Access Journals (Sweden)

    Nemat Eskandarzadeh

    2007-08-01

    Full Text Available

    Background and aims. It is critical to have a proper knowledge of the normal anatomy of the pulp and its variations for the success of endodontic treatment. The aim of this study was to determine the canal configuration and the prevalence of C-shaped canals in mandibular first and second premolars in a North-Western Iranian population.

    Materials and methods. A total of 163 extracted mandibular first and 103 mandibular second premolars were injected with India ink and demineralized . They were made clear and transparent with methyl salicylate and the anatomy of their canal(s was studied.

    Results. The results showed that 98% of mandibular first premolars had one root, 2% had two roots, 70.6% had one canal, 27.8% had two canals, 1.2% had three canals and the prevalence of C-shaped canals was 2.4%. All mandibular second premolars had one root, 80.5% had one canal, 17.5% had two canals and the prevalence of C-shaped canals was 2%.

    Conclusion. It is important that clinicians, before treatment of mandibular first and second premolars, pay complete attention to radiographs, have a true concept of the number of root(s and canal(s, and prepare a correct access cavitiy.

  11. Asymptotic scalings of developing curved pipe flow

    Science.gov (United States)

    Ault, Jesse; Chen, Kevin; Stone, Howard

    2015-11-01

    Asymptotic velocity and pressure scalings are identified for the developing curved pipe flow problem in the limit of small pipe curvature and high Reynolds numbers. The continuity and Navier-Stokes equations in toroidal coordinates are linearized about Dean's analytical curved pipe flow solution (Dean 1927). Applying appropriate scaling arguments to the perturbation pressure and velocity components and taking the limits of small curvature and large Reynolds number yields a set of governing equations and boundary conditions for the perturbations, independent of any Reynolds number and pipe curvature dependence. Direct numerical simulations are used to confirm these scaling arguments. Fully developed straight pipe flow is simulated entering a curved pipe section for a range of Reynolds numbers and pipe-to-curvature radius ratios. The maximum values of the axial and secondary velocity perturbation components along with the maximum value of the pressure perturbation are plotted along the curved pipe section. The results collapse when the scaling arguments are applied. The numerically solved decay of the velocity perturbation is also used to determine the entrance/development lengths for the curved pipe flows, which are shown to scale linearly with the Reynolds number.

  12. RETRATAMENTO ENDODÔNTICO: ESTUDO COMPARATIVO ENTRE TÉCNICA MANUAL, ULTRA-SOM E CANAL FINDER ENDODONTIC RETREATMENT: COMPARATIVE STUDY BETWEEN MANUAL TECHNIQUE, ULTRASONIC SCALER, AND CANAL FINDER

    Directory of Open Access Journals (Sweden)

    Clovis Monteiro BRAMANTE

    1998-01-01

    Full Text Available Instrumentações manual, ultra-sônica e com Canal Finder foram utilizadas para retratamento de 30 dentes com canais obturados com guta-percha e óxido de zinco e eugenol. Avaliaram-se: 1. tempo gasto para a penetração inicial até o ápice; 2. tempo para completar a limpeza; 3. extrusão de material e 4. limpeza dos canais. O Canal Finder foi a técnica que propiciou melhor limpeza, seguida da manual e da ultra-sônica. A parede palatina do canal foi constantemente mais limpa do que a vestibular. Quanto à extrusão, a técnica de ultra-som foi a que propiciou mais extravasamento de material obturador.Endodontic retreatment of 30 teeth filled with guta percha and zinc oxide-eugenol was carried out using manual instrumentation, ultrasonic scaler, and the Canal Finder System. The following variables were evaluated: time spent to reach the apex; time spent to complete cleaning of the canal; apical extrusion of material; and cleanliness of the canals. Results showed the Canal Finder System as providing the highest level of cleanliness of the canal system; lingual walls were constantly cleaner than buccal walls; ultrasonic technique presented a greater degree of apical extrusion of filling material.

  13. Computed tomography imaging for superior semicircular canal dehiscence syndrome

    International Nuclear Information System (INIS)

    Dobeli, Karen

    2006-01-01

    Superior semicircular canal dehiscence is a newly described syndrome of sound and/or pressure induced vertigo. Computed tomography (CT) imaging plays an important role in confirmation of a defect in the bone overlying the canal. A high resolution CT technique utilising 0.5 mm or thinner slices and multi-planar reconstructions parallel to the superior semicircular canal is required. Placement of a histogram over a suspected defect can assist CT diagnosis

  14. Influence of root canal sealer on the radiographic appearance of filling voids in maxillary single-rooted teeth

    Directory of Open Access Journals (Sweden)

    Augusto Bodanezi

    2012-08-01

    Full Text Available OBJECTIVE: This study compared the influence of three epoxy resin-based sealers with distinct radiopacities on the observers' ability to detect root canal filling voids during radiographic analysis. MATERIAL AND METHODS: The root canals of 48 extracted maxillary canines were prepared and divided into three groups. Each group was laterally condensed with one sealer (AH Plus®, Acroseal® or a non-radiopaque sealer, and a longitudinal void was simulated in half of the specimens from each group (n=8. Buccolingual radiographs were obtained and randomly interpreted for voids by a radiologist and an endodontist in a blinded fashion. Teeth were cut and inspected under a microscope to confirm the position of void. Differences in sensitivity and specificity between groups and examiners were compared using the Fisher's Exact and McNemar tests, respectively (α=0.05. RESULTS: Significantly lower sensitivity levels (p<0.05 were observed in the coronal portion of fillings performed with both radiopaque sealers. Specificity values for Acroseal® were significantly higher (p<0.05 in the coronal and apical portions of fillings. CONCLUSIONS: The type of root canal sealer can affect the observers' ability to detect root canal filling voids during radiographic analysis of upper single-rooted teeth.

  15. Interaction of Aquifer and River-Canal Network near Well Field.

    Science.gov (United States)

    Ghosh, Narayan C; Mishra, Govinda C; Sandhu, Cornelius S S; Grischek, Thomas; Singh, Vikrant V

    2015-01-01

    The article presents semi-analytical mathematical models to asses (1) enhancements of seepage from a canal and (2) induced flow from a partially penetrating river in an unconfined aquifer consequent to groundwater withdrawal in a well field in the vicinity of the river and canal. The nonlinear exponential relation between seepage from a canal reach and hydraulic head in the aquifer beneath the canal reach is used for quantifying seepage from the canal reach. Hantush's (1967) basic solution for water table rise due to recharge from a rectangular spreading basin in absence of pumping well is used for generating unit pulse response function coefficients for water table rise in the aquifer. Duhamel's convolution theory and method of superposition are applied to obtain water table position due to pumping and recharge from different canal reaches. Hunt's (1999) basic solution for river depletion due to constant pumping from a well in the vicinity of a partially penetrating river is used to generate unit pulse response function coefficients. Applying convolution technique and superposition, treating the recharge from canal reaches as recharge through conceptual injection wells, river depletion consequent to variable pumping and recharge is quantified. The integrated model is applied to a case study in Haridwar (India). The well field consists of 22 pumping wells located in the vicinity of a perennial river and a canal network. The river bank filtrate portion consequent to pumping is quantified. © 2014, National GroundWater Association.

  16. Evolution of canals system linking the Vistula, Dnieper and Neman basins

    Science.gov (United States)

    Brykala, Dariusz; Badziai, Vitali

    2014-05-01

    The aim of this study is to reconstruct landscape changes in the Polesie Region - one of the largest European swampy areas (Belarus), as a result of the creation and operation of a network of canals. From the 16th century efforts were undertaken to connect the Polish areas located in the drainage basins of the Black Sea and Baltic Sea with canals. Already in 1631 the Polish Sejm (parliament) approved the project to build a canal linking the River Berezina (Dnieper basin) with the River Neris (Neman basin). However, the complicated political and economic situation of the country did not allow doing this. Only in the second half of the 18th c. hetman Ogiński financed the construction of a canal linking the Dnieper and Neman basins. The canal connecting the River Szczara (Neman basin) with the River Jasiołda (Pripyat basin) was named after its creator - the Ogiński Canal. At the same time the construction of the Królewski (Royal) Canal linking the River Muchavets (Vistula basin) and the River Pina (Pripyat basin) was under way. The construction of the canal was completed in 1783. The winding channels of the Pina and Muchavets were straightened, and the numerous canals feeding the waterway system drained vast area of marshes and wetlands of the Polesia Region. The last element that connects the catchments of the Vistula and Neman is the Augustów Canal built in the years 1825-1839 (linking the catchments of the Biebrza and Neman). Numerous changes in political boundaries in the watershed area between the Black Sea and the Baltic Sea drainage basins caused the destruction of the hydraulic structures. All the analysed canals were completely destroyed during the two world wars. In the last 200 years the amount and type of locks and weirs has changed. For example, there were no weirs on the Royal Canal in the late 18th c., in the middle of the 19th c. there were 22 such structures, while now that number has gone down to 10. All canals were created for economic reasons

  17. Effect of Instrument Design and Access Outlines on the Removal of Root Canal Obturation Materials in Oval-shaped Canals.

    Science.gov (United States)

    Niemi, Tuomas K; Marchesan, Melissa A; Lloyd, Adam; Seltzer, Robert J

    2016-10-01

    The aim of this study was to compare the effectiveness of TRUShape (TS) instruments with ProFile Vortex Blue (VB) instruments for the removal of obturation materials during retreatment of single-canal mandibular premolars performed through 2 access outlines. Initial root canal treatment was completed through a contracted endodontic cavity (CEC) design. Canals were instrumented to an F2 ProTaper instrument, obturated with warm lateral condensation of gutta-percha with AH Plus sealer, and allowed to set for 30 days at 37°C and 100% humidity. For retreatment, specimens were divided into 2 groups (n = 24) on the basis of access outline, CEC or traditional endodontic cavity (TEC). Retreatment was initiated by using ProTaper Retreatment instruments (D1-D3). Specimens were then stratified, further divided (n = 12), and reinstrumented up to TS 40 .06v or 40 .06 VB. Irrigation was performed by using 8.25% NaOCl and QMix 2in1. Retreatment time was recorded. Teeth were sectioned and photographed, and the percentage of remaining obturation materials was measured. Data were analyzed with Kruskal-Wallis analysis of variance for two-factor tests (α canal surface when compared with TEC-VB, CEC-TS, and TEC-TS (P ≤ .05). None of these other combinations were different from each other (P > .05). Significantly more time was required for retreatment with CEC-TS (27.68 ± 1.4 minutes) than the other groups (P root canal surface of mandibular premolars. However, in the presence of a CEC access design, using TS instruments removed more obturating material in single-rooted, oval-shaped canals. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  18. Root canal preparation in endodontics: conventional versus laser methods

    Science.gov (United States)

    Goodis, Harold E.; White, Joel M.; Marshall, Sally J.; Marshall, Grayson W.; Moskowitz, Emrey

    1992-06-01

    Conventional cleaning and shaping of root canal systems employs hand and/or rotary instrumentation to remove the contents of the canal and shape the canal to receive a filling material. With the advent of the Nd:YAG laser system another method of accomplishing proper cleaning and shaping is evaluated. Single rooted teeth were radiographed bucco- lingually and mesio-distally and were divided into 2 groups. The first group was accessed and the root canal systems cleaned and shaped with a step back technique utilizing hand files and gates glidden burs. At completion of the procedure the teeth were again radiographed at the same positions as those prior to the procedure. The teeth were split longitudinally and examined under scanning electron microscopy to assess cleaning. The second group of teeth were accessed, and cleaning and shaping was accomplished using the Nd:YAG laser in combination with hand files and rotary instruments. These teeth were subjected to the same analysis as those in the first group. The before and after radiographs of each group were subjected to image analysis to determine effectiveness of the two methods in shaping the canal systems. We will discuss the ability of Nd:YAG to clean and shape root canal spaces and remove smear layer and organic tissue remnants from those areas.

  19. Preclinical endoscopic training using a part-task simulator: learning curve assessment and determination of threshold score for advancement to clinical endoscopy.

    Science.gov (United States)

    Jirapinyo, Pichamol; Abidi, Wasif M; Aihara, Hiroyuki; Zaki, Theodore; Tsay, Cynthia; Imaeda, Avlin B; Thompson, Christopher C

    2017-10-01

    Preclinical simulator training has the potential to decrease endoscopic procedure time and patient discomfort. This study aims to characterize the learning curve of endoscopic novices in a part-task simulator and propose a threshold score for advancement to initial clinical cases. Twenty novices with no prior endoscopic experience underwent repeated endoscopic simulator sessions using the part-task simulator. Simulator scores were collected; their inverse was averaged and fit to an exponential curve. The incremental improvement after each session was calculated. Plateau was defined as the session after which incremental improvement in simulator score model was less than 5%. Additionally, all participants filled out questionnaires regarding simulator experience after sessions 1, 5, 10, 15, and 20. A visual analog scale and NASA task load index were used to assess levels of comfort and demand. Twenty novices underwent 400 simulator sessions. Mean simulator scores at sessions 1, 5, 10, 15, and 20 were 78.5 ± 5.95, 176.5 ± 17.7, 275.55 ± 23.56, 347 ± 26.49, and 441.11 ± 38.14. The best fit exponential model was [time/score] = 26.1 × [session #] -0.615 ; r 2  = 0.99. This corresponded to an incremental improvement in score of 35% after the first session, 22% after the second, 16% after the third and so on. Incremental improvement dropped below 5% after the 12th session corresponding to the predicted score of 265. Simulator training was related to higher comfort maneuvering an endoscope and increased readiness for supervised clinical endoscopy, both plateauing between sessions 10 and 15. Mental demand, physical demand, and frustration levels decreased with increased simulator training. Preclinical training using an endoscopic part-task simulator appears to increase comfort level and decrease mental and physical demand associated with endoscopy. Based on a rigorous model, we recommend that novices complete a minimum of 12 training

  20. ROUTING DEMAND CHANGES TO USERS ON THE WM LATERAL CANAL WITH SACMAN

    Science.gov (United States)

    Most canals have either long travel times or insufficient in-canal storage to operate on-demand. Thus, most flow changes must be routed through the canal. Volume compensation has been proposed as a method for easily applying feedforward control to irrigation canals. SacMan (Software for Automated Ca...

  1. MR determination of neonatal spinal canal depth.

    Science.gov (United States)

    Arthurs, Owen; Thayyil, Sudhin; Wade, Angie; Chong, W K Kling; Sebire, Neil J; Taylor, Andrew M

    2012-08-01

    Lumbar punctures (LPs) are frequently performed in neonates and often result in traumatic haemorrhagic taps. Knowledge of the distance from the skin to the middle of the spinal canal (mid-spinal canal depth - MSCD) may reduce the incidence of traumatic taps, but there is little data in extremely premature or low birth weight neonates. Here, we determined the spinal canal depth at post-mortem in perinatal deaths using magnetic resonance imaging (MRI). Spinal canal depth was measured in 78 post-mortem foetuses and perinatal cases (mean gestation 26 weeks; mean weight 1.04kg) at the L3/L4 inter-vertebral space at post-mortem MRI. Both anterior (ASCD) and posterior (PSCD) spinal canal depth were measured; MSCD was calculated and modelled against weight and gestational age. ASCD and PSCD (mm) correlated significantly with weight and gestational age (all r>0.8). A simple linear model MSCD (mm)=3×Weight (kg)+5 was the best fit, identifying an SCD value within the correct range for 87.2% (68/78) (95% CI (78.0, 92.9%)) cases. Gestational age did not add significantly to the predictive value of the model. There is a significant correlation between MSCD and body weight at post-mortem MRI in foetuses and perinatal deaths. If this association holds in preterm neonates, use of the formula MSCD (mm)=3×Weight (kg)+5 could result in fewer traumatic LPs in this population. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  2. MR determination of neonatal spinal canal depth

    Energy Technology Data Exchange (ETDEWEB)

    Arthurs, Owen, E-mail: owenarthurs@uk2.net [Centre for Cardiovascular MR, Great Ormond Street Hospital for Children, London WC1N 3JH (United Kingdom); Thayyil, Sudhin, E-mail: s.thayyil@ucl.ac.uk [Academic Neonatology, Institute for Women' s Health, London WC1E 6AU (United Kingdom); Wade, Angie, E-mail: a.wade@ucl.ac.uk [Centre for Paediatric Epidemiology and Biostatistics, UCL Institute of Child Health, London (United Kingdom); Chong, W.K., E-mail: Kling.Chong@gosh.nhs.uk [Paediatric Neuroradiology, Great Ormond Street Hospital for Children, London (United Kingdom); Sebire, Neil J., E-mail: Neil.Sebire@gosh.nhs.uk [Histopathology, Great Ormond Street Hospital for Children, London WC1E 6AU (United Kingdom); Taylor, Andrew M., E-mail: a.taylor76@ucl.ac.uk [Centre for Cardiovascular MR, Cardiorespiratory Unit, Great Ormond Street Hospital for Children and UCL Institute of Cardiovascular Science, London WC1E 6AU (United Kingdom)

    2012-08-15

    Objectives: Lumbar punctures (LPs) are frequently performed in neonates and often result in traumatic haemorrhagic taps. Knowledge of the distance from the skin to the middle of the spinal canal (mid-spinal canal depth - MSCD) may reduce the incidence of traumatic taps, but there is little data in extremely premature or low birth weight neonates. Here, we determined the spinal canal depth at post-mortem in perinatal deaths using magnetic resonance imaging (MRI). Patients and methods: Spinal canal depth was measured in 78 post-mortem foetuses and perinatal cases (mean gestation 26 weeks; mean weight 1.04 kg) at the L3/L4 inter-vertebral space at post-mortem MRI. Both anterior (ASCD) and posterior (PSCD) spinal canal depth were measured; MSCD was calculated and modelled against weight and gestational age. Results: ASCD and PSCD (mm) correlated significantly with weight and gestational age (all r > 0.8). A simple linear model MSCD (mm) = 3 Multiplication-Sign Weight (kg) + 5 was the best fit, identifying an SCD value within the correct range for 87.2% (68/78) (95% CI (78.0, 92.9%)) cases. Gestational age did not add significantly to the predictive value of the model. Conclusion: There is a significant correlation between MSCD and body weight at post-mortem MRI in foetuses and perinatal deaths. If this association holds in preterm neonates, use of the formula MSCD (mm) = 3 Multiplication-Sign Weight (kg) + 5 could result in fewer traumatic LPs in this population.

  3. CANAL user's manual

    International Nuclear Information System (INIS)

    Faya, A.; Wolf, L.; Todreas, N.

    1979-11-01

    CANAL is a subchannel computer program for the steady-state and transient thermal hydraulic analysis of BWR fuel rod bundles. The purpose of this manual is to introduce the user into the mechanism of running the code by providing information about the input data and options

  4. GEOPOLITICS AND TRANSPORTATION. UNITED STATES AND PANAMA CANAL

    Directory of Open Access Journals (Sweden)

    Benea Ciprian Beniamin

    2009-05-01

    Full Text Available This article presents the great connection which exists between the realization of Panama Canal and the rising power on United States; and how this state, after the construction of this canal, could promote efficiently at global level its interests.

  5. "Alarm-corrected" ergonomic armrest use could improve learning curves of novices on robotic simulator.

    Science.gov (United States)

    Yang, Kun; Perez, Manuela; Hossu, Gabriela; Hubert, Nicolas; Perrenot, Cyril; Hubert, Jacques

    2017-01-01

    In robotic surgery, the professional ergonomic habit of using an armrest reduces operator fatigue and increases the precision of motion. We designed and validated a pressure surveillance system (PSS) based on force sensors to investigate armrest use. The objective was to evaluate whether adding an alarm to the PSS system could shorten ergonomic training and improve performance. Twenty robot and simulator-naïve participants were recruited and randomized in two groups (A and B). The PSS was installed on a robotic simulator, the dV-Trainer, to detect contact with the armrest. The Group A members completed three tasks on the dV-Trainer without the alarm, making 15 attempts at each task. The Group B members practiced the first two tasks with the alarm and then completed the final tasks without the alarm. The simulator provided an overall score reflecting the trainees' performance. We used the new concept of an "armrest load" score to describe the ergonomic habit of using the armrest. Group B had a significantly higher performance score (p ergonomic errors and accelerated professional ergonomic habit acquisition. The combination of the PSS and alarm is effective in significantly shortening the learning curve in the robotic training process.

  6. SCADA system with predictive controller applied to irrigation canals

    OpenAIRE

    Figueiredo, João; Botto, Miguel; Rijo, Manuel

    2013-01-01

    This paper applies a model predictive controller (MPC) to an automatic water canal with sensors and actuators controlled by a network (programmable logic controller), and supervised by a SCADA system (supervisory control and a data acquisition). This canal is composed by a set of distributed sub-systems that control the water level in each canal pool, constrained by discharge gates (control variables) and water off-takes (disturbances). All local controllers are available through an industria...

  7. Endodontic management of a mandibular first molar with six root canal systems.

    Science.gov (United States)

    Jain, Dilip; Reddy, Smitha; Venigalla, Bhuvan Shome; Kamishetty, Shekhar

    2015-01-01

    Internal anatomy of pulp is complex. The first mandibular molars typically have two roots, one mesial with two root canals and another distal root, which contains one or two canals. A 20-year-old female patient reported with intermittent pain and incomplete root canal treatment in left lower back region since 1-week. Refined access cavity revealed initially two canals in mesial and two canals in the distal root. With operating microscope and cone beam computerized tomography, two additional canals (L-mesio-buccal and B-mesio-lingual) were identified in mesial root. One-year follow-up showed patient was asymptomatic and complete healing of periapical radiolucency.

  8. Topographical evaluation of the mandibular canal through panoramic radiograph

    Directory of Open Access Journals (Sweden)

    Ingrid Macedo Oliveira

    2016-10-01

    Full Text Available The mandibular canal is located inside the body of the mandible and may have anatomical variations. The topographic knowledge of the mandibular canal by the Dental surgeons is fundamental to achieving success in surgical planning, anesthetics and clinical interventions involving the jaw. To study the anatomy of the mandibular canal through panoramic radiographs. A retrospective descriptive study, developed after review and approval by the Ethics and Research Committee with the number of opinion 431095. Were analyzed 252 panoramic radiographs of patients of male and female attended in dental clinics UNINOVAFAPI University Center, Teresina-Pi, Brazil. The radiographs were analyzed with the aid of a light box and each antimere the jaw was observed separately. The classification of Nortjé and Langlais for description of the topography of the mandibular canal were used. Descriptive statistical analysis was performed with SPSS version 18.0. There was a prevalence of 38.89% in both antimeres, of mandibular channel the Type II. The type IV was present in 25.4% in the right hemi-arch and 26.6% on the left. Mandibular canal with unilateral bifurcation was observed in 0.77% of the sample and molar straight channel has not been identified. We observed anatomical variations as for the number and path, of the mandibular canal with the highest prevalence of Types II and IV, and the absence of bifurcations. Most was mandibular channels showed no bifurcation. The panoramic radiograph showed up an aid important to identify the mandibular canal and its variations.

  9. Cervical spinal canal narrowing and cervical neurologi-cal injuries

    Directory of Open Access Journals (Sweden)

    ZHANG Ling

    2012-04-01

    Full Text Available 【Abstract】Cervical spinal canal narrowing can lead to injury of the spinal cord and neurological symptoms in-cluding neck pain, headache, weakness and parasthesisas. According to previous and recent clinical researches, we investigated the geometric parameters of normal cervical spinal canal including the sagittal and transverse diameters as well as Torg ratio. The mean sagittal diameter of cervical spinal canal at C 1 to C 7 ranges from 15.33 mm to 20.46 mm, the mean transverse diameter at the same levels ranges from 24.45 mm to 27.00 mm and the mean value of Torg ratio is 0.96. With respect to narrow cervical spinal canal, the following charaterstics are found: firstly, extension of the cervical spine results in statistically significant stenosis as compared with the flexed or neutral positions; secondly, females sustain cervical spinal canal narrowing more easily than males; finally, the consistent narrowest cervical canal level is at C 4 for all ethnicity, but there is a slight variation in the sagittal diameter of cervical spinal stenosis (≤14 mm in Whites, ≤ 12 mm in Japanese, ≤13.7 mm in Chinese. Narrow sagittal cervical canal diameter brings about an increased risk of neurological injuries in traumatic, degenerative and inflam-matory conditions and is related with extension of cervical spine, gender, as well as ethnicity. It is hoped that this re-view will be helpful in diagnosing spinal cord and neuro-logical injuries with the geometric parameters of cervical spine in the future. Key words: Spinal cord injuries; Spinal stenosis; Trauma, nervous system

  10. Evaluation of surface preparation and maintenance of canal curvature following instrumentation with hand ′K′ file and three different Ni-Ti rotary systems: A radiographic and SEM study

    Directory of Open Access Journals (Sweden)

    Namrata Bhatti

    2010-01-01

    Full Text Available Aim: To determine the shaping ability and cleaning efficiency of hand K-flexofiles, ProTaper, LightSpeed and Mtwo instruments during the preparation of curved root canals in extracted human teeth. Materials and Methods: A total of 120 root canals of mandibular and maxillary molars with curvature more than 20° were divided into four groups of 30 each. In group A, canals were prepared using hand K-flexofiles following the crown down technique. In group B LightSpeed, in group C ProTaper, and in group D Mtwo rotary instruments were used to prepare the root canals. Using pre- and post-instrumentation radiographs, straightening of the canal curvature was determined with Corel Draw 9.0 software tools. The amount of debris and smear layer were quantified at three different areas (coronal, middle, and apical thirds of root canal using SEM. The collected data were analyzed statistically using Student′s paired ′t′ test. Results: The mean change in curvature for hand K-files was 7.71°, for ProTaper files 6.03°, for Mtwo 5.43°, and for LightSpeed instruments were found to be 4.57°. The percentage change in the curvature for all the four groups was statistically highly significant (P< 0.01. LightSpeed instruments maintained the original canal curvature significantly (P< 0.01 better than the other instruments. For leftover debris, the minimum percentage was found to be associated with ProTaper (65.48% followed by Mtwo (66.22%, LightSpeed (71.67% and the maximum with hand K-files (74.16%. However, the difference in mean leftover debris between ProTaper and Mtwo was not significant. Conclusion: ProTaper and Mtwo resulted in good cleaning, and LightSpeed maintained the original canal curvature better than the ProTaper, Mtwo, or Hand K-files.

  11. Superior Canal Dehiscence Syndrome: Lessons from the First 20 Years

    Directory of Open Access Journals (Sweden)

    Bryan K. Ward

    2017-04-01

    Full Text Available Superior semicircular canal dehiscence syndrome was first reported by Lloyd Minor and colleagues in 1998. Patients with a dehiscence in the bone overlying the superior semicircular canal experience symptoms of pressure or sound-induced vertigo, bone conduction hyperacusis, and pulsatile tinnitus. The initial series of patients were diagnosed based on common symptoms, a physical examination finding of eye movements in the plane of the superior semicircular canal when ear canal pressure or loud tones were applied to the ear, and high-resolution computed tomography imaging demonstrating a dehiscence in the bone over the superior semicircular canal. Research productivity directed at understanding better methods for diagnosing and treating this condition has substantially increased over the last two decades. We now have a sound understanding of the pathophysiology of third mobile window syndromes, higher resolution imaging protocols, and several sensitive and specific diagnostic tests. Furthermore, we have a treatment (surgical occlusion of the superior semicircular canal that has demonstrated efficacy. This review will highlight some of the fundamental insights gained in SCDS, propose diagnostic criteria, and discuss future research directions.

  12. A review of potential tsunami impacts to the Suez Canal

    Science.gov (United States)

    Finkl, C.; Pelinovsky, E.

    2012-04-01

    Destructive tsunamis in the eastern Mediterranean and Red seas, induced by earthquakes and/or volcanic activity, pose potential hazards to docked seaport shipping and fixed harbor infrastructure as well as to in-transit international shipping within the Suez Canal. Potential vulnerabilities of the Suez Canal to possible tsunami impacts are reviewed by reference to geological, historical, archaeoseismological, and anecdotal data. Tsunami catalogues and databases compiled by earlier researchers are perused to estimate potential return periods for tsunami events that could affect directly the Suez Canal and its closely associated operational infrastructures. Analysis of these various records indicates a centurial return period, or multiples thereof, for long-wave repetition that could generally affect the Nile Delta. It is estimated that tsunami waves 2 m high would have a breaking length about 5 km down Canal whereas a 10 m wave break would occur about 1 km into the Canal. Should a tsunami strike the eastern flanks of the Nile Delta, it would damage Egypt's maritime infrastructure and multi-national commercial vessels and military ships then using the Canal.

  13. Study of mastoid canals and grooves in north karnataka human skulls.

    Science.gov (United States)

    Hadimani, Gavishiddappa Andanappa; Bagoji, Ishwar Basavantappa

    2013-08-01

    This study was undertaken to observe the frequency of mastoid canals and grooves in north Karnataka dry human skulls. 100 dry human skulls of unknown age and sex from the department of Anatomy were selected and observed for the present study. The mastoid regions of dry skulls were observed for the presence of mastoid canals and grooves, if any. A metallic wire was passed through the canal for its confirmation and then the length was measured. The Mastoid canals were present in 53% of the total 100 skulls observed either bilaterally or unilaterally. Mastoid grooves were present in 18% of the total skulls (100) observed. Double mastoid canal was found in 01% of total skull studied and both Mastoid canals & Mastoid grooves together were present in 02% of the total skulls (100) observed. The knowledge of mastoid canals and grooves is very important for otolaryngologists and neurosurgeons. Because they contain an arterial branch of occipital artery with its accompanying vein which is liable to injury resulting into severe bleeding.

  14. Two-Rooted Maxillary First Molars with Two Canals: A Case Series

    OpenAIRE

    Shakouie, Sahar; Mokhtari, Hadi; Ghasemi, Negin; Gholizadeh, Seddigheh

    2013-01-01

    Thorough understanding of the anatomic and internal morphology of a root canal system is absolutely essential for the success of endodontic treatment. Since permanent maxillary first molars have shown variation in internal anatomy, morphology, this tooth has been reviewed extensively. Presence of two canals in a two-rooted maxillary first molar has rarely been reported in studies describing tooth and root canal anatomies. In this report, three cases are presented, which involve the root canal...

  15. Development of Rating Curve Estimators for Suspended-Sediment Concentration and Transport in the C-51 Canal Based on Surrogate Technology, Palm Beach County, Florida, 2004-05

    National Research Council Canada - National Science Library

    Lietz, A. C; Debiak, Elizabeth A

    2005-01-01

    .... The major cause of these sediment deposits most likely is due to stormwater heavily laden with fluvial sediment, discharging through the S-155 control structure on the West Palm Beach (C-51) Canal...

  16. Effect of Suez Canal Marine Sediment on Sorption of Cesium

    International Nuclear Information System (INIS)

    Hassan, H.B.

    2016-01-01

    Suez Canal is surrounded by navigation, industrial, agricultural activities and suffers from high rate of population growth that discharging waste into Suez Canal. The Suez Canal coastal waters are influenced by a complex variety of physical, geochemical and biological processes, which influence the behavior, transport and fate of containments released into the marine environment. Sorption of releasing containment such as cesium in Suez Canal water is investigated because of its toxic effect on the marine environment. The object of present study is to determine the effects some of physical and chemical characteristics of collected sediment samples from the three important locations on Suez Canal (Suez Bay, Bitter Lakes and El- Temsah Lake beaches) on sorption behavior of cesium by using batch experiment. Batch experiment was used to study the sorption of the cesium ion. The sorption process is dependent on mineral constituents of Suez Canal sediment and their characteristics. Analytical methods which included particle size and X-ray diffraction (XRD) analyses found that particle size of Suez Canal sediment samples is characterized by sand to fine sand and quartz is the main mineralogical species. Distribution coefficient (K d ) which represent geochemical processes and particle size of these sediment samples effect on the degree of cesium sorption to the sediment. Also (K d ) increase with increase cation exchangeable capacity (CEC). The Suez Canal sediment samples have low (K d ) values which effected by their physical and chemical properties. Sample (2) has highest distribution coefficient (K d ) between measured samples due to containing ratio 30% of fine sand and high ratio of organic matter.

  17. Viperous fangs: development and evolution of the venom canal.

    Science.gov (United States)

    Zahradnicek, Oldrich; Horacek, Ivan; Tucker, Abigail S

    2008-01-01

    Fangs are specialised long teeth that contain either a superficial groove (Gila monster, Beaded lizard, some colubrid snakes), along which the venom runs, or an enclosed canal (viperid, elapid and atractaspid), down which the venom flows inside the tooth. The fangs of viperid snakes are the most effective venom-delivery structures among vertebrates and have been the focus of scientific interests for more than 200 years. Despite this interest the questions of how the canal at the centre of the fang forms remains unresolved. Two different hypotheses have been suggested. The mainstream hypothesis claims that the venom-conducting canal develops by the invagination of the epithelial wall of the developing tooth germ. The sides of this invagination make contact and finally fuse to form the enclosed canal. The second hypothesis, known as the "brick chimney", claims the venom-conducting canal develops directly by successive dentine deposition as the tooth develops. The fang is thus built up from the tip to the base, without any folding of the tooth surface. In an attempt to cast further light on this subject the early development of the fangs was followed in a pit viper, Trimeresurus albolabris, using the expression of Sonic hedgehog (Shh). We demonstrate that the canal is indeed formed by an early folding event, resulting from an invagination of epithelial cells into the dental mesenchyme. The epithelial cells proliferate to enlarge the canal and then the cells die by apoptosis, forming an empty tube through which the poison runs. The entrance and discharge orifices at either end of the canal develop by a similar invagination but the initial width of the invagination is very different from that in the middle of the tooth, and is associated with higher proliferation. The two sides of the invaginating epithelium never come into contact, leaving the orifice open. The mechanism by which the orifices form can be likened to that observed in reptiles with an open groove along

  18. CT and MR Imagings of Semicircular Canal Aplasia

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Chung Hee; Hong, Hyun Sook; Yi, Beom Ha; Cha, Jang Gyu; Park, Seong Jin; Kim, Dae Ho; Lee, Hae Kyung; Kim, Shi Chan [Soonchunhyang University Bucheon Hospital, Bucheon (Korea, Republic of)

    2009-07-15

    To evaluate the clinical, CT and MR imaging findings of semicircular canal (SCC) aplasia and to evaluate if a correlation exists between these findings and the associated anomalies or syndromes. This study retrospectively reviewed the CT and MRI findings of five patients with SCC aplasia. The CT and MR findings were analyzed for SCC, direction of facial nerve canal, cochlea, vestibule, oval or round window, middle ear ossicles, and internal auditory canal (IAC). The subjects included three boys and two girls ranging in age from one to 120 months (mean age; 51 months). Four of the subjects had the CHARGE syndrome, and one had the Goldenhar syndrome. Moreover, four subjects had sensorineural hearing loss and one had combined hearing loss. The course of the facial nerve canal was abnormal in all five cases. Moreover, trapped cochlea and dysplastic modiolus were each observed in one case. Four subjects had atresia of the oval window; whereas ankylosis of the ossicles was present in three subjects. IAC stenosis was present in one patient with the CHARGE syndrome. The aberrant course of the facial nerve canal, atresia of the oval window, and abnormal ossicles were frequently associated in patients with SCC aplasia. In addition, the Goldenhar and CHARGE syndromes were also commonly associated syndromes.

  19. Kyphoplasty for osteoporotic fractures with spinal canal compromise

    International Nuclear Information System (INIS)

    Gan Minfeng; Yang Huilin; Zou Jun; Wang Genlin; Mei Xin; Zhou Feng; Chen Liang; Jiang Weimin

    2010-01-01

    Objective: To explore the feasibility and clinical outcome of kyphoplasty in the treatment of osteoporotic fractures with canal compromise. Methods: A total of 16 patients with osteoporotic fractures with canal compromise without neurological deficit were attempted to be treated by kyphoplasty. During kyphoplasty, modified techniques including staged bone cement injection and dynamic fluoroscopic monitoring were used. Pain was measured using the self-reporting Visual Analogue pain Scale (VAS) preoperatively, postoperatively and in the final follow-up. Disability was measured using the Oswestry Disability questionnaire (ODI) preoperatively, postoperatively and in the final follow-up. The height of the compromised vertebral body, the kyphotic angle and the spinal canal compromise were measured preoperatively, postoperatively and in the final follow-up. Results: Operations were completed smoothly, with the exception of one patient with less cement leakage but without clinical symptom occurred. Relief of pain was achieved after kyphoplasty. The mean VAS score of these patients decreased from 8.1 ± 1.2 pre-operatively to 2.7 ± 0.6 post-operatively (P 0.05). In the final follow-up, the spinal canal compromise was (14.4 ± 3.1)%. Conclusion: Kyphoplasty is a relatively safe and effective method for the treatment of osteoporotic fractures with canal compromise without neurological deficit. (authors)

  20. Numerical modeling of simultaneous tracer release and piscicide treatment for invasive species control in the Chicago Sanitary and Ship Canal, Chicago, Illinois

    Science.gov (United States)

    Zhu, Zhenduo; Motta, Davide; Jackson, P. Ryan; Garcia, Marcelo H.

    2017-01-01

    In December 2009, during a piscicide treatment targeting the invasive Asian carp in the Chicago Sanitary and Ship Canal, Rhodamine WT dye was released to track and document the transport and dispersion of the piscicide. In this study, two modeling approaches are presented to reproduce the advection and dispersion of the dye tracer (and piscicide), a one-dimensional analytical solution and a three-dimensional numerical model. The two approaches were compared with field measurements of concentration and their applicability is discussed. Acoustic Doppler current profiler measurements were used to estimate the longitudinal dispersion coefficients at ten cross sections, which were taken as reference for calibrating the longitudinal dispersion coefficient in the one-dimensional analytical solution. While the analytical solution is fast, relatively simple, and can fairly accurately predict the core of the observed concentration time series at points downstream, it does not capture the tail of the breakthrough curves. These tails are well reproduced by the three-dimensional model, because it accounts for the effects of dead zones and a power plant which withdraws nearly 80 % of the water from the canal for cooling purposes before returning it back to the canal.

  1. Endodontic Shaping Performance Using Nickel–Titanium Hand and Motor ProTaper Systems by Novice Dental Students

    Directory of Open Access Journals (Sweden)

    Ming-Gene Tu

    2008-05-01

    Conclusion: These findings show that the novice students prepared the simulated curved canal that deviated more outwardly from apical 1 mm to 4 mm using the hand ProTaper. The ability to maintain the original curvature was better in the motor rotary ProTaper group than in the hand ProTaper group. Undergraduate students, if following the preparation sequence carefully, could successfully perform canal shaping by motor ProTaper files and achieve better root canal geometry than by using hand ProTaper files within the same teaching and practicing sessions.

  2. Mechanics of the Panama Canal slides

    Science.gov (United States)

    Becker, George F.

    1917-01-01

    Dr. Becker visited the Canal Zone in 1913 as a geologist of the United States Geological Survey and since that time has given the problem the benefit of his study. His appointment as a member of the committee of the National Academy of Sciences has made it appropriate for his conclusions, based upon his personal observations and already reported in part to the Canal Commission, to be stated for the benefit of his associates and other American scientists and engineers.

  3. Reflected Light Curves of Extrasolar Planets

    Science.gov (United States)

    Green, D.; Matthews, J.; Kuschnig, R.; Seager, S.

    The planned launches of ultra-precise photometric satellites such as MOST, COROT and MONS should provide the first opportunity to study the reflected light curves from extrasolar planets. To predict the capabilities of these missions, we have constructed a series of models of such light curves, improving upon the Monte Carlo simulations by Seager et al. (2000). These models include more realistic features such limb darkening of the star and broad band photometry. For specific models, the resulting planet light curves exhibit unique behavior with the variation of radius, inclination and presence or absence of clouds.

  4. tgcd: An R package for analyzing thermoluminescence glow curves

    Directory of Open Access Journals (Sweden)

    Jun Peng

    2016-01-01

    Full Text Available Thermoluminescence (TL glow curves are widely used in dosimetric studies. Many commercial and free-distributed programs are used to deconvolute TL glow curves. This study introduces an open-source R package tgcd to conduct TL glow curve analysis, such as kinetic parameter estimation, glow peak simulation, and peak shape analysis. TL glow curves can be deconvoluted according to the general-order empirical expression or the semi-analytical expression derived from the one trap-one recombination center (OTOR model based on the Lambert W function by using a modified Levenberg–Marquardt algorithm from which any of the parameters can be constrained or fixed. The package provides an interactive environment to initialize parameters and offers an automated “trial-and-error” protocol to obtain optimal fit results. First-order, second-order, and general-order glow peaks (curves are simulated according to a number of simple kinetic models. The package was developed using a combination of Fortran and R programming languages to improve efficiency and flexibility.

  5. Impaired Curve Negotiation in Drivers with Parkinson’s Disease

    Directory of Open Access Journals (Sweden)

    Ergun Y Uç

    2009-03-01

    Full Text Available OBJECTIVE: To assess the ability to negotiate curves in drivers with Parkinson’s disease (PD. METHODS: Licensed active drivers with mild-moderate PD (n= 76; 65 male, 11 female and elderly controls (n= 51; 26 male, 25 female drove on a simulated 2-lane rural highway in a high-fidelity simulator scenario in which the drivers had to negotiate 6 curves during a 37-mile drive. The participants underwent motor, cognitive, and visual testing before the simulator drive. RESULTS: Compared to controls, the drivers with PD had less vehicle control and driving safety, both on curves and straight baseline segments, as measured by significantly higher standard deviation of lateral position (SDLP and lane violation counts. The PD group also scored lower on tests of motor, cognitive, and visual abilities. In the PD group, lower scores on tests of motion perception, visuospatial ability, executive function, postural instability, and general cognition, as well as a lower level of independence in daily activities predicted low vehicle control on curves. CONCLUSION: Drivers with PD had less vehicle control and driving safety on curves compared to controls, which was associated primarily with impairments in visual perception and cognition, rather than motor function

  6. Root canal treatment of a maxillary first premolar with three roots

    OpenAIRE

    Mathew, Josey; Devadathan, Aravindan; Syriac, Gibi; Shamini, Sai

    2015-01-01

    Successful root canal treatment needs a thorough knowledge of both internal and external anatomy of a tooth. Variations in root canal anatomy constitute an impressive challenge to the successful completion of endodontic treatment. Undetected extra roots and canals are a major reason for failed root canal treatment. Three separate roots in a maxillary first premolar have a very low incidence of 0.5?6%. Three rooted premolars are anatomically similar to molars and are sometimes called ?small mo...

  7. 3D-printed pediatric endoscopic ear surgery simulator for surgical training.

    Science.gov (United States)

    Barber, Samuel R; Kozin, Elliott D; Dedmon, Matthew; Lin, Brian M; Lee, Kyuwon; Sinha, Sumi; Black, Nicole; Remenschneider, Aaron K; Lee, Daniel J

    2016-11-01

    Surgical simulators are designed to improve operative skills and patient safety. Transcanal Endoscopic Ear Surgery (TEES) is a relatively new surgical approach with a slow learning curve due to one-handed dissection. A reusable and customizable 3-dimensional (3D)-printed endoscopic ear surgery simulator may facilitate the development of surgical skills with high fidelity and low cost. Herein, we aim to design, fabricate, and test a low-cost and reusable 3D-printed TEES simulator. The TEES simulator was designed in computer-aided design (CAD) software using anatomic measurements taken from anthropometric studies. Cross sections from external auditory canal samples were traced as vectors and serially combined into a mesh construct. A modified tympanic cavity with a modular testing platform for simulator tasks was incorporated. Components were fabricated using calcium sulfate hemihydrate powder and multiple colored infiltrants via a commercial inkjet 3D-printing service. All components of a left-sided ear were printed to scale. Six right-handed trainees completed three trials each. Mean trial time (n = 3) ranged from 23.03 to 62.77 s using the dominant hand for all dissection. Statistically significant differences between first and last completion time with the dominant hand (p 3D-printed simulator is feasible for TEES simulation. Otolaryngology training programs with access to a 3D printer may readily fabricate a TEES simulator, resulting in inexpensive yet high-fidelity surgical simulation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  8. Endodontic management of radix paramolaris with six canals: a clinical case report.

    Science.gov (United States)

    Acharya, N; Singh, A; Samant, P S; Gautam, V

    2013-01-01

    Endodontic therapy of mandibular molars is a challenging task due to its varied root canal morphology. A mandibular first molar with additional buccal root (Radix paramolaris) and additional distolingual root (Radix Entomolaris) is an example of its varied anatomy. A successful management of atypical root canal configurations is an important aspect in determining the success rate of root canal therapy. The detail knowledge of the root morphology and canal anatomy allows the clinician for accurate location of the extra roots and canals and accordingly the refinement of the access cavity for the stress free entry of complex anatomy. Hence, for a successful root canal therapy, clinician must be aware of the external and internal anatomic variations .The aim of this clinical case report is to present and describe the unusual presence of two separate mesial roots and six root canals in mandibular first molar, detected during routine endodontic therapy.

  9. An In Vitro Comparative Study of Intracanal Fluid Motion and Wall Shear Stress Induced by Ultrasonic and Polymer Rotary Finishing Files in a Simulated Root Canal Model

    OpenAIRE

    Koch, Jon; Borg, John; Mattson, Abby; Olsen, Kris; Bahcall, James

    2012-01-01

    Objective. This in vitro study compared the flow pattern and shear stress of an irrigant induced by ultrasonic and polymer rotary finishing file activation in an acrylic root canal model. Flow visualization analysis was performed using an acrylic canal filled with a mixture of distilled water and rheoscopic fluid. The ultrasonic and polymer rotary finishing file were separately tested in the canal and activated in a static position and in a cyclical axial motion (up and down). Particle moveme...

  10. Characterizing time series via complexity-entropy curves

    Science.gov (United States)

    Ribeiro, Haroldo V.; Jauregui, Max; Zunino, Luciano; Lenzi, Ervin K.

    2017-06-01

    The search for patterns in time series is a very common task when dealing with complex systems. This is usually accomplished by employing a complexity measure such as entropies and fractal dimensions. However, such measures usually only capture a single aspect of the system dynamics. Here, we propose a family of complexity measures for time series based on a generalization of the complexity-entropy causality plane. By replacing the Shannon entropy by a monoparametric entropy (Tsallis q entropy) and after considering the proper generalization of the statistical complexity (q complexity), we build up a parametric curve (the q -complexity-entropy curve) that is used for characterizing and classifying time series. Based on simple exact results and numerical simulations of stochastic processes, we show that these curves can distinguish among different long-range, short-range, and oscillating correlated behaviors. Also, we verify that simulated chaotic and stochastic time series can be distinguished based on whether these curves are open or closed. We further test this technique in experimental scenarios related to chaotic laser intensity, stock price, sunspot, and geomagnetic dynamics, confirming its usefulness. Finally, we prove that these curves enhance the automatic classification of time series with long-range correlations and interbeat intervals of healthy subjects and patients with heart disease.

  11. Root canal morphology of primary molars: a micro-computed tomography study.

    Science.gov (United States)

    Fumes, A C; Sousa-Neto, M D; Leoni, G B; Versiani, M A; da Silva, L A B; da Silva, R A B; Consolaro, A

    2014-10-01

    This was to investigate the root canal morphology of primary molar teeth using micro-computed tomography. Primary maxillary (n = 20) and mandibular (n = 20) molars were scanned at a resolution of 16.7 μm and analysed regarding the number, location, volume, area, structured model index (SMI), area, roundness, diameters, and length of canals, as well as the thickness of dentine in the apical third. Data were statistically compared by using paired-sample t test, independent sample t test, and one-way analysis of variance with significance level set as 5%. Overall, no statistical differences were found between the canals with respect to length, SMI, dentine thickness, area, roundness, and diameter (p > 0.05). A double canal system was observed in the mesial and mesio-buccal roots of the mandibular and maxillary molars, respectively. The thickness in the internal aspect of the roots was lower than in the external aspect. Cross-sectional evaluation of the roots in the apical third showed flat-shaped canals in the mandibular molars and ribbon- and oval-shaped canals in the maxillary molars. External and internal anatomy of the primary first molars closely resemble the primary second molars. The reported data may help clinicians to obtain a thorough understanding of the morphological variations of root canals in primary molars to overcome problems related to shaping and cleaning procedures, allowing appropriate management strategies for root canal treatment.

  12. Optimizing the chemical aspect of root canal irrigation

    NARCIS (Netherlands)

    de Macedo, R.G.

    2013-01-01

    Root canal treatment is aimed at the removal of inflamed and infected tissue present in the root canal system. It will prevent the entrance of new microorganisms or nutrients in order to maintain or create a healthy environment around the root. There is sufficient evidence that shows that

  13. Forced extrusion for removal of impacted third molars close to the mandibular canal Extrusión forzada para extraer los terceros molares impactados cerca del canal mandibular

    Directory of Open Access Journals (Sweden)

    Dennis Flanagan DDS

    2012-03-01

    Full Text Available Impacted mandibular third molars can be located in close proximity to the mandibular canal. This creates a risk for the nerve or artery injury. These are contained in the canal. However, the impacted third molar can be moved coronally by orthodontic means, after removal of overlying bone, and safely extracted. The orthodontic intervention slowly moves the tooth apex away from the mandibular canal and reduces the potential for a neural injury. This method may be useful for older patients with root apices that approximate or are actually located in the mandibular canal. This technique needs further study. There is a theoretical potential for neural or arterial injury from physical contact of the tooth apex as it moves by or through the mandibular canal.Los terceros molares inferiores impactados pueden localizarse muy cerca del canal mandibular. Esto constituye un riesgo de lesión del nervio o la arteria, que se localizan dentro del canal. No obstante, el tercer molar impactado puede desplazarse en dirección coronal con ortodoncia, tras ostectomía del hueso suprayacente, y extraerse sin riesgos. La intervención ortodóncica desplaza lentamente el ápice del diente fuera del canal mandibular y reduce la posibilidad de lesión neural. Este método puede ser útil para pacientes de edad avanzada con ápices dentales que se aproximan o en realidad se localizan en el canal mandibular. La técnica necesita un estudio adicional. Hay la posibilidad teórica de lesión neural o arterial a partir del contacto físico del ápice del diente a medida que se desplaza a través del canal mandibular.

  14. Three-dimensional analysis of mesiobuccal root canal of Japanese maxillary first molar using Micro-CT

    International Nuclear Information System (INIS)

    Yamada, Masashi; Ide, Yoshinobu; Matsunaga, Satoru; Kato, Hiroshi; Nakagawa, Kan-Ichi

    2011-01-01

    The objective of this study was to three-dimensionally observe the morphological characteristics of mesiobuccal root canals of Japanese maxillary first molars using microcomputed tomography (Micro-CT) and classify root canal variations. This study used 90 maxillary first molars. Three-dimensional reconstruction was performed using data obtained by Micro-CT, and cross-sections of the root canals were observed. Moreover, the root canal morphology was classified by the configuration and root canal diameter, and was evaluated for occurrence using the classification by Weine et al. (1969) as a reference. Overall, single root canals were observed in 44.4%, incomplete separation root canals in 22.3%, and completely separate root canals (upper and lower separation root canals) in 33.3%. Mesiobuccal root canals often had intricate configurations, and accessory root canals (lateral canals and apical ramifications) were observed in most of the mesiobuccal root canals (76.7%), irrespective of whether there were ramifications of the main root canals. While there were no marked differences in the incidence of root canal ramifications between this study and earlier reports, the incidence of accessory root canals was higher in this study. This result may be explained by the far more superior visualization ability of Micro-CT than conventional methods, which allowed the detection of microscopic apical ramifications previously difficult to observe. (author)

  15. AFSC/ABL: Lynn Canal Overwinter Acoustic Survey, 2004-2005

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The acoustic trawl database for Lynn Canals echo-trawl survey was conducted from 2001 to 2004 throughout southern Lynn Canal in southeast Alaska. Acoustic surveys...

  16. Direct and CT measurements of canals and foramina of the skull base

    International Nuclear Information System (INIS)

    Berlis, A.; Schumacher, M.; Putz, R.

    1992-01-01

    This investigation is based on measurements of 60 macerated adult European skulls from the Alexander-Ecker Collection at the Anatomy Department of the University of Freiburg. Computer tomographical (CT) and anatomical measurements were compared to assess the accuracy of the CT representation of osseous structures. Nine structures were examined: the optic canal, superior orbital fissure, foramen rotundum, foramen ovale, foramen spinosum,foramen Vesalii (venosum), carotid canal, internal auditory canal and hypoglossal canal. Results show a good and even excellent correlation if the cranial opening is approximately at a right angle to the scanline. For this reason, the results of the coronal examination of the internal auditory canal are less satisfactory, and the coronal and axial measurements of the hypoglossal canal show only a moderately good correlation. (author)

  17. On the ecological role of Copepoda in the Suez Canal marine ...

    African Journals Online (AJOL)

    Moreover, the importance of copepods in the marine food web and secondary productivity in the canal water, as well as their response to environmental variations in the Suez Canal ecosystem were discussed. KEY WORDS: Zooplankton, Copepoda, food web, marine ecosystem, Suez Canal Egyptian Journal of Biology ...

  18. Root canal treatment of bilateral three-rooted maxillary first premolars

    Directory of Open Access Journals (Sweden)

    Bhavana Gandhi

    2012-01-01

    Full Text Available In endodontics, several anatomic variations occur in teeth, both externally and in the internal root morphology, which play a very significant role in the diagnosis and treatment outcome. A thorough knowledge of the root canal anatomy, careful interpretation of the angled radiographs, proper endodontic access cavity preparation, and exploration of the root canal are the prerequisites for endodontic success. In a maxillary first premolar, it is rare to find extra roots and canals, and the aim of the present article is to report a case about the successful diagnosis and clinical management of bilateral three-rooted maxillary first premolars, with three independent root canals.

  19. Radioactivity level of the gamma emitters in Ismailia Canal environment

    International Nuclear Information System (INIS)

    Abdel Malik, W.E.Y.; Youssef, S.K.; Ibrahim, A.S.

    1993-01-01

    The activity level of the γ-emitting radionuclides was measured in the different component of Ismalia Canal (bottom sediment, biota and water) by γ-spectrometry. The average activity level of the dry samples ranged from 12 to 89 Bq/kg for the detected natural radionuclides. The annual external γ-dose to the living organisms in the canal, close to the sediment beds, was found to be in the range of 1.21±0.24 mSv/y and does not present any significant hazards when compared with the natural γ-ray background around the Ismalia Canal(IC) environment which ranges from 0.80 to 1.73 mSv/y. (orig.)

  20. Radiographic analysis of odontogenic cysts showing displacement of the mandibular canal

    International Nuclear Information System (INIS)

    Cho, Bong Hae

    2003-01-01

    To assess the radiographic findings of odontogenic cysts showing displacement of the mandibular canal using computed tomographic (CT) and panoramic images. CT and panoramic images of 63 odontogenic cysts (27 dentigerous, 16 odontogenic keratocysts, and 20 radicular cysts) were analyzed to evaluate the following parameters: the dimension and shape of the cysts, and the effect of the cysts on the mandibular canal and cortical plates. Of the 63 cysts examined in the study, 35 (55.6%) showed inferior displacement of the mandibular canal and 46 (73.0%) showed perforation of the canal. There were statistically significant differenced between CT and panoramic images in depicting displacement and perforation of the mandibular canal. Cortical expansion was seen in 46 cases (73.0%) and cortical perforation in 23 cases (36.5%). The radicular cysts showed cortical expansion and perforation less frequently than the other cyst groups. Large cysts of mandible should be evaluated by multiplanar CT images in order to detect the mandibular canal and cortical bone involvement.

  1. Root and Canal Morphology of Mandibular Third Molars in an Iranian Population

    Directory of Open Access Journals (Sweden)

    Maryam Kuzekanani

    2012-06-01

    Full Text Available Background and aims. A through knowledge of the root canal morphology is required for successful endodontic therapy. The aim of this study was to investigate the root and canal morphology of mandibular third molars in Kerman, a province in southeast of Iran. Materials and methods. One-hundred-fifty extracted mandibular third molars were collected randomly from different dental clinics in Kerman. The root canal anatomy and morphology of each tooth was carefully studied using a clearing technique. Root number and morphology, number of canals per root, root canal configuration according to Vertucci classification, and incidence of dilacerated roots and C-shaped canals in mandibular third molars were evaluated under stereomicroscope with ×2 to ×3 magnifications. Results. From the total of 150 mandibular third molars studied, 21% had one root. The majority of teeth (73% had two roots. 5.5% of the teeth had three roots. The incidence of C-shaped canal was 3.5% in this study and 8% of the teeth had at least one dilacerated root. Conclusion. Although root canal anatomy and morphology of mandibular third molars is very variable having two roots seems to be the normal anatomy for these teeth.

  2. Effectiveness of Various Irrigation Protocols in Removing Calcium Hydroxide from Root Canals

    Directory of Open Access Journals (Sweden)

    Hakan Göktürk

    2018-04-01

    Full Text Available Objective: The purpose of this study was to investigate the removal efficiency of calcium hydroxide (CH by CanalBrush, Vibringe, laser-activated irrigation (LAI, conventional syringe irrigation (CSI, XP-endo Finisher, and passive ultrasonic irrigation (PUI in the root canal walls. Materials and Methods: Ninety-eight human mandibular premolar teeth were prepared. Root canals were filled with CH. The roots were divided into six experimental groups (n=15/group according to the irrigation protocol used: group 1 (CSI, group 2 (Vibringe, group 3 (CanalBrush, group 4 (XP-endo Finisher, group 5 (PUI, and group 6 (LAI. The amount of residual CH in the canal walls for each canal third was scored. Data were analysed by using Kruskal-Wallis and Bonferroni-correction Mann-Whitney U tests. Results: None of the investigated protocols renders the root canal walls free of CH remnants. Significant differences were found between tooth regions in terms of CH removal (p<0.05, and all groups except group 6 (LAI showed more residual CH in the apical region. PUI and LAI eliminated significantly more CH than CSI from the middle and apical thirds of the root canal, respectively. Conclusion: The activation of sodium hypochlorite with various devices increased CH removal at the apical and middle part of the canal. LAI and PUI produce better results in the apical and middle thirds, respectively.

  3. A central incisor with 4 independent root canals: a case report

    NARCIS (Netherlands)

    Aznar Portoles, C.; Moinzadeh, A.T.; Shemesh, H.

    2015-01-01

    The maxillary central incisor is the tooth with the least anatomic variations. Despite the fact that several studies have reported a prevalence of 100% for the presence of a single canal, root canal aberrations of maxillary central incisors with up to 3 canals have also been reported. Such cases

  4. Synthesization of the Ar VIII 3s-3p beam-foil decay curve

    International Nuclear Information System (INIS)

    Lindgaard, A.; Veje, E.

    1981-01-01

    The beam-foil decay curve for the 3s-3p transition in Ar VIII has been simulated from experimentally determined relative initial level populations and transition probabilities calculated in the numerical Coulomb approximation. Good agreement is observed between simulated and measured decay curves. A discussion of the simulation is given. (Auth.)

  5. Two-rooted maxillary first molars with two canals: a case series.

    Science.gov (United States)

    Shakouie, Sahar; Mokhtari, Hadi; Ghasemi, Negin; Gholizadeh, Seddigheh

    2013-01-01

    Thorough understanding of the anatomic and internal morphology of a root canal system is absolutely essential for the success of endodontic treatment. Since permanent maxillary first molars have shown variation in internal anatomy, morphology, this tooth has been reviewed extensively. Presence of two canals in a two-rooted maxillary first molar has rarely been reported in studies describing tooth and root canal anatomies. In this report, three cases are presented, which involve the root canal treatment of maxillary first molars with fusion of the two buccal roots.

  6. File list: His.CDV.05.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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    Lifescience Database Archive (English)

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    Lifescience Database Archive (English)

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  10. File list: Unc.CDV.50.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  11. File list: His.CDV.10.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  12. File list: His.CDV.50.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  13. File list: Unc.CDV.10.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.CDV.10.AllAg.Atrioventicular_canals mm9 Unclassified Cardiovascular Atrioventicular canals... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Unc.CDV.10.AllAg.Atrioventicular_canals.bed ...

  14. QUANTITATIVE SIZE ASSESSMENT OF THE LUMBAR SPINAL CANAL BY COMPUTED TOMOGRAPHY

    Directory of Open Access Journals (Sweden)

    M. Midia Z. Miabi

    2007-08-01

    Full Text Available By determining normal ranges of spinal canal diameters we can make early diagnosis in persons who have lower diameters of spinal canal. These persons are predisposed to spinal canal stenosis that is a major cause of spinal radiculopathies. In different studies performed in several countries, minimum and maximum ranges of spinal canal diameters were different for each population. In this study, we tried to determine the mean values of normal spinal canal diameters and areas in Tabriz and its suburb. 39 healthy, young to mid-age cases were selected. Our study was focused on L3-L4 and L4-L5. The following parameters were measured: the area of cross-section of the vertebral body, the area of cross-section of the dural sac, interarticular diameter, interligamentous diameter, antero-posterior diameter of the lumbar canal, inter-pedicular diameter, and the area of cross-section of the vertebral canal. A correlation between the parameters studied and the height of subjects was significant for interligamentous diameter (for L3/L4 and L4/L5 and interarticular diameter (only at L3/L4, cross-section area of the vertebrae (both L3 and L4, cross-section area of vertebral canal (only at L5 level, area of dural sac (at L3/L4 and L4. It was suggested that these diameters and areas should be interpreted as a unction of height of the subject. Most of diameters studied had smaller means than those in previous studies. This can be attributed to differences between populations and it can be interpreted as predisposition to spinal canal stenosis in our population.

  15. Canal configuration of mandibular first premolars in an Egyptian population

    Directory of Open Access Journals (Sweden)

    Hatem A. Alhadainy

    2013-03-01

    Full Text Available The purpose of this study was to investigate canal configuration of mandibular first premolars in an Egyptian population. Two hundred fifty human extracted mandibular first premolars were collected from Egyptian patients and a small hole in the center of the occlusal surface of each tooth was made perforating the roof of the pulp chamber. Teeth were decalcified by immersing in nitric acid and dehydrated in ascending concentrations of ethyl alcohol. A waterproof black ink was passively injected from the occlusal hole into pulp system and stained teeth were immersed in methyl salicylate solution for clearing. Standardized pictures of the cleared teeth were obtained and anatomical features of the root canal were observed. The average length of the mandibular first premolar teeth was 22.48 ± 1.74 mm, one-rooted teeth were 96.8% and the two-rooted were 3.2%. Vertucci Type I canal configuration represented the highest percentage (61.2% followed by Type V (16.4%, Type IV (13.2%, Type II (5.6% and Type III (2.8%. Vertucci Type VI canal configuration represented the lowest percentage (0.4% and a complex configuration was found in one tooth. Accessory canals were detected in 22.8% and inter-canal connections were observed in 24.8% while 54% showed apical delta. Such knowledge is clinically useful for localization and negotiation of canals of mandibular first premolar, as well as their subsequent management in Egyptian population.

  16. Research on the Integration of Bionic Geometry Modeling and Simulation of Robot Foot Based on Characteristic Curve

    Science.gov (United States)

    He, G.; Zhu, H.; Xu, J.; Gao, K.; Zhu, D.

    2017-09-01

    The bionic research of shape is an important aspect of the research on bionic robot, and its implementation cannot be separated from the shape modeling and numerical simulation of the bionic object, which is tedious and time-consuming. In order to improve the efficiency of shape bionic design, the feet of animals living in soft soil and swamp environment are taken as bionic objects, and characteristic skeleton curve, section curve, joint rotation variable, position and other parameters are used to describe the shape and position information of bionic object’s sole, toes and flipper. The geometry modeling of the bionic object is established by using the parameterization of characteristic curves and variables. Based on this, the integration framework of parametric modeling and finite element modeling, dynamic analysis and post-processing of sinking process in soil is proposed in this paper. The examples of bionic ostrich foot and bionic duck foot are also given. The parametric modeling and integration technique can achieve rapid improved design based on bionic object, and it can also greatly improve the efficiency and quality of robot foot bionic design, and has important practical significance to improve the level of bionic design of robot foot’s shape and structure.

  17. The 'Amstel Canal' in Amsterdam Canal construction as part of the medieval reclamation and drainage system of the Western Netherlands wilderness

    Science.gov (United States)

    Abrahamse, Jaap-Evert; Kosian, Menne; Weerts, Henk

    2013-04-01

    Usually, Amsterdam is presented as a river city, with the river Amstel as the trade route towards its hinterland, the IJ sea-branch as the portal to the world and its Dam as a focal point of transshipment and trade. Geomorphological, sedimentological, historical and historical-geographical evidence however, points towards the straight part of the Amstel, now located in Amsterdam, as a drainage canal that was dug in the aftermath of the 'Great Reclamation' of the 11th and 12th centuries. During this period, large parts of the wilderness in Utrecht and Holland were cultivated and put to agricultural use. Prior to the 'Great Reclamations', large oligotrophic (Sphagnum) peat bogs drained by small rivers were characteristic of the entire region. All along the straight Amstel canal, Sphagnum peat is found, which is indicative of the area's former peat bog conditions. The 'Amstel Canal' connected two natural meandering watercourses, one at the north and one at the south of the canal. The soil along both watercourses exists of eutrophic peat, which is indicative of repeated natural flooding. This is a strong indication of the anthropogenous origin of the straight part of the Amstel. The reason for digging the Amstel canal was not to create better trade links; it was a local component of a solution for major regional drainage problems in the provinces of Utrecht and Holland. These problems arose from the silting up of the Rhine rivermouth around 1100AD. Because of this, the precipitation surplus of the entire region could not be drained to the North Sea by this route anymore. This led to increased flooding and subsequently to conflicts between the rulers of Holland and Utrecht. In 1165AD, these conflicts reached a point where the Holy Roman Emperor intervened. The ruling of Barbarossa eventually led to a compromise: Utrecht and Holland redirected the entire drainage system of the region from the North Sea to the Zuiderzee in a concerted effort. This operation consisted of

  18. Piquet Caroline, Histoire du canal de Suez, Paris, Perrin, 2009, 372 p.

    Directory of Open Access Journals (Sweden)

    Claudine Piaton

    2011-01-01

    Full Text Available Les études sur l'histoire du canal de Suez connaissent un regain d'intérêt chez les historiens français. Nathalie Montel avait ouvert la voie en 1998 en publiant un ouvrage passionnant sur le percement du canal, Le chantier du canal de Suez, 1859-1869. Une histoire des pratiques techniques. L'étude s'arrêtait à l'ouverture du canal en 1869, laissant le champ libre à de futurs travaux. La publication en 2008 de l'ouvrage de Caroline Piquet, La Compagnie du canal de Suez, une concession françai...

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    Lifescience Database Archive (English)

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  20. File list: Pol.CDV.05.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  1. File list: Pol.CDV.50.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  2. File list: DNS.CDV.50.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  3. File list: Pol.CDV.20.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  4. File list: DNS.CDV.05.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  5. File list: DNS.CDV.10.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  6. File list: DNS.CDV.20.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  7. Greater Activity in the Frontal Cortex on Left Curves: A Vector-Based fNIRS Study of Left and Right Curve Driving.

    Directory of Open Access Journals (Sweden)

    Noriyuki Oka

    Full Text Available In the brain, the mechanisms of attention to the left and the right are known to be different. It is possible that brain activity when driving also differs with different horizontal road alignments (left or right curves, but little is known about this. We found driver brain activity to be different when driving on left and right curves, in an experiment using a large-scale driving simulator and functional near-infrared spectroscopy (fNIRS.The participants were fifteen healthy adults. We created a course simulating an expressway, comprising straight line driving and gentle left and right curves, and monitored the participants under driving conditions, in which they drove at a constant speed of 100 km/h, and under non-driving conditions, in which they simply watched the screen (visual task. Changes in hemoglobin concentrations were monitored at 48 channels including the prefrontal cortex, the premotor cortex, the primary motor cortex and the parietal cortex. From orthogonal vectors of changes in deoxyhemoglobin and changes in oxyhemoglobin, we calculated changes in cerebral oxygen exchange, reflecting neural activity, and statistically compared the resulting values from the right and left curve sections.Under driving conditions, there were no sites where cerebral oxygen exchange increased significantly more during right curves than during left curves (p > 0.05, but cerebral oxygen exchange increased significantly more during left curves (p < 0.05 in the right premotor cortex, the right frontal eye field and the bilateral prefrontal cortex. Under non-driving conditions, increases were significantly greater during left curves (p < 0.05 only in the right frontal eye field.Left curve driving was thus found to require more brain activity at multiple sites, suggesting that left curve driving may require more visual attention than right curve driving. The right frontal eye field was activated under both driving and non-driving conditions.

  8. Greater Activity in the Frontal Cortex on Left Curves: A Vector-Based fNIRS Study of Left and Right Curve Driving

    Science.gov (United States)

    Oka, Noriyuki; Yoshino, Kayoko; Yamamoto, Kouji; Takahashi, Hideki; Li, Shuguang; Sugimachi, Toshiyuki; Nakano, Kimihiko; Suda, Yoshihiro; Kato, Toshinori

    2015-01-01

    Objectives In the brain, the mechanisms of attention to the left and the right are known to be different. It is possible that brain activity when driving also differs with different horizontal road alignments (left or right curves), but little is known about this. We found driver brain activity to be different when driving on left and right curves, in an experiment using a large-scale driving simulator and functional near-infrared spectroscopy (fNIRS). Research Design and Methods The participants were fifteen healthy adults. We created a course simulating an expressway, comprising straight line driving and gentle left and right curves, and monitored the participants under driving conditions, in which they drove at a constant speed of 100 km/h, and under non-driving conditions, in which they simply watched the screen (visual task). Changes in hemoglobin concentrations were monitored at 48 channels including the prefrontal cortex, the premotor cortex, the primary motor cortex and the parietal cortex. From orthogonal vectors of changes in deoxyhemoglobin and changes in oxyhemoglobin, we calculated changes in cerebral oxygen exchange, reflecting neural activity, and statistically compared the resulting values from the right and left curve sections. Results Under driving conditions, there were no sites where cerebral oxygen exchange increased significantly more during right curves than during left curves (p > 0.05), but cerebral oxygen exchange increased significantly more during left curves (p right premotor cortex, the right frontal eye field and the bilateral prefrontal cortex. Under non-driving conditions, increases were significantly greater during left curves (p right frontal eye field. Conclusions Left curve driving was thus found to require more brain activity at multiple sites, suggesting that left curve driving may require more visual attention than right curve driving. The right frontal eye field was activated under both driving and non-driving conditions

  9. IGMtransmission: Transmission curve computation

    Science.gov (United States)

    Harrison, Christopher M.; Meiksin, Avery; Stock, David

    2015-04-01

    IGMtransmission is a Java graphical user interface that implements Monte Carlo simulations to compute the corrections to colors of high-redshift galaxies due to intergalactic attenuation based on current models of the Intergalactic Medium. The effects of absorption due to neutral hydrogen are considered, with particular attention to the stochastic effects of Lyman Limit Systems. Attenuation curves are produced, as well as colors for a wide range of filter responses and model galaxy spectra. Photometric filters are included for the Hubble Space Telescope, the Keck telescope, the Mt. Palomar 200-inch, the SUBARU telescope and UKIRT; alternative filter response curves and spectra may be readily uploaded.

  10. Teacher's Guide to Canal. The Middlesex Canal: A Role Playing Exercise.

    Science.gov (United States)

    Holmes, Cary W.; Tedesco, Paul H.

    The document consists of a role-playing game and related teacher's guide designed to illustrate decision-making processes leading to the building of the Middlesex Canal in Massachusetts in 1793. The primary educational objective is to involve students in the decision-making process through role play. The game is designed to facilitate…

  11. Strategies of Coping With Stress During Root Canal Therapy

    Directory of Open Access Journals (Sweden)

    Zare Jahromi

    2015-12-01

    Full Text Available Background Endodontic treatment is one of the stress producing situations. Objectives The purpose of this article was to determine the most stressful stage of root canal therapy among endodontists, endodontic residents, and undergraduate dental students and offering some strategies for reducing stress during this treatment. Patients and Methods This descriptive survey comprised three groups. Thirty-six endodontists, 41 endodontic residents, and 47 undergraduate dental students selected by convenience sampling. Participants were asked about age, sex, the most stressful stage of root canal therapy and stress reducing strategies during the procedure. Results The most stressful stage of root canal therapy was endodontic treatment for children in male endodontists and residents, preparing access cavity on crowns in female endodontists, obturation of apically root Resorped canals in female residents, obturation in female students, and preparing access cavity on molar teeth in male students. The most suggested strategy for reducing stress during root canal therapy was related to experience, knowledge, enough study, and technical mastery. Conclusions It is required to consider the strategies during student education in dental schools for both under and post-graduation dental students and better to follow them in workshops for other dentists and even endodontists.

  12. Review of root canal irrigant delivery techniques and devices

    Directory of Open Access Journals (Sweden)

    Yeon-Jee Yoo

    2011-05-01

    Full Text Available Introduction Eliminating the residual debris and bacteria in the root canal system is one of the main purposes of the endodontic treatment. However, the complexity on the anatomy of the root canal system makes it difficult to eliminate the bacterial biofilm existing along the root canal surface and necrotic pulp tissue by mechanical instrumentation and chemical irrigation. Recently, more effective irrigant delivery systems for root canal irrigation have been developed. The purpose of this review was to present an overview of root canal irrigant delivery techniques and devices available in endodontics. Review The contents of this paper include as follows; - syringe-needle irrigation, manual dynamic irrigation, brushes - sonic and ultrasonic irrigation, passive ultrasonic irrigation, rotary brush, RinsEndo, EndoVac, Laser Conclusion Though technological advances during the last decade have brought to fruition new agitation devices that rely on various mechanisms, there are few evidence based study to correlate the clinical efficacy of these devices with improved outcomes except syringe irrigation with needle and ultrasonic irrigation. The clinicians should try their best efforts to deliver antimicrobial and tissue solvent solutions in predictable volumes safely to working length.

  13. Learning Curves of Virtual Mastoidectomy in Distributed and Massed Practice

    DEFF Research Database (Denmark)

    Andersen, Steven Arild Wuyts; Konge, Lars; Cayé-Thomasen, Per

    2015-01-01

    IMPORTANCE: Repeated and deliberate practice is crucial in surgical skills training, and virtual reality (VR) simulation can provide self-directed training of basic surgical skills to meet the individual needs of the trainee. Assessment of the learning curves of surgical procedures is pivotal...... in understanding skills acquisition and best-practice implementation and organization of training. OBJECTIVE: To explore the learning curves of VR simulation training of mastoidectomy and the effects of different practice sequences with the aim of proposing the optimal organization of training. DESIGN, SETTING...... plateaued on a score of 16.0 (15.3-16.7) at approximately the ninth repetition, but the individual learning curves were highly variable. CONCLUSIONS AND RELEVANCE: Novices can acquire basic mastoidectomy competencies with self-directed VR simulation training. Training should be organized with distributed...

  14. Prominent central spinal canal on MRI - normal variant or pathology

    International Nuclear Information System (INIS)

    Dugal, T.P.; Brazier, D.; Roche, J.

    2002-01-01

    Full text: The sensitivity of MRI can make differentiation of normal from abnormal challenging.The study investigates whether a visible central spinal canal is pathological or a normal variant. We review eight MRI (mostly on a 1.5 Tesla unit) cases where there is a visible central cavity in keeping with a central canal and review the literature. The central canal is a space in the medial part of the grey-matter commissure between the anterior and posterior horns. Histopathological studies show that the canal is present at birth with the majority showing subsequent involution but is uncommonly imaged on MRI. The main differential diagnosis is syringomyelia which usually presents with deficits in pain and sensation corresponding to the appropriate level often with a demonstrable aetiology. Two thirds of our patients were female with an average age of thirty-six years (range 26-45). The patients were largely asymptomatic or their symptoms appeared unrelated to the imaging findings. Three patients had minor previous trauma and two others had non-bacterial meningitis up to twenty years earlier. No patient had known spinal surgery or trauma.The cavity corresponded tomographically to the expected site of the central canal. The canal was in the thoracic location. The canal diameter ranged from one to five millimetres and its length varied from one half a vertebral body height to extending over the entire thoracic region. Its configuration was either filiform or fusiform, with smooth contours. No predisposing features to suggest syringomyelia or other structural abnormalities were noted. Where Gadolinium was given no abnormal enhancement was observed. These cases add to the literature and suggest that these prominent canals are largely asymptomatic and should be viewed as normal variants. Copyright (2002) Blackwell Science Pty Ltd

  15. Adaptation and penetration of resin-based root canal sealers in root canals irradiated with high-intensity lasers

    Science.gov (United States)

    Moura-Netto, Cacio; Mello-Moura, Anna Carolina Volpi; Palo, Renato Miotto; Prokopowitsch, Igor; Pameijer, Cornelis H.; Marques, Marcia Martins

    2015-03-01

    This research analyzed the quality of resin-based sealer adaptation after intracanal laser irradiation. Extracted teeth (n=168) were root canal treated and divided into four groups, according to dentin surface treatment: no laser; Nd:YAG laser (1.5 W, 100 mJ, 15 Hz) diode laser (2.5 W in CW), and Er:YAG laser (1 W, 100 mJ, 10 Hz). The teeth were divided into four subgroups according to the sealer used: AH Plus, EndoREZ, Epiphany, and EpiphanySE. For testing the sealing after root canal obturation, the penetration of silver nitrate solution was measured, whereas to evaluate the adaptation and penetration of the sealer into the dentin, environmental scanning electron microscopy (ESEM) was used. The ESEM images were analyzed using a four-grade criteria score by three evaluators. The inter-examiner agreement was confirmed by Kappa test and the scores statistically compared by the Kruskal-Wallis' test (p<0.05). Both adaptation and sealer penetration in root canals were not affected by the laser irradiation. Nd:YAG and diode laser decreased the tracer penetration for AH Plus, whereas EndoREZ and EpiphanySE performances were affected by Nd:YAG irradiation (p<0.05). It can be concluded that intracanal laser irradiation can be used as an adjunct in endodontic treatment; however, the use of hydrophilic resin sealers should be avoided when root canals were irradiated with Nd:YAG laser.

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    Lifescience Database Archive (English)

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  17. File list: ALL.CDV.20.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  18. File list: ALL.CDV.05.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  19. File list: ALL.CDV.50.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.CDV.50.AllAg.Atrioventicular_canals mm9 All antigens Cardiovascular Atrioventicular canals... SRX1271841 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/ALL.CDV.50.AllAg.Atrioventicular_canals.bed ...

  20. Cervical spinal canal narrowing in idiopathic syringomyelia

    International Nuclear Information System (INIS)

    Struck, Aaron F.; Carr, Carrie M.; Shah, Vinil; Hesselink, John R.; Haughton, Victor M.

    2016-01-01

    The cervical spine in Chiari I patient with syringomyelia has significantly different anteroposterior diameters than it does in Chiari I patients without syringomyelia. We tested the hypothesis that patients with idiopathic syringomyelia (IS) also have abnormal cervical spinal canal diameters. The finding in both groups may relate to the pathogenesis of syringomyelia. Local institutional review boards approved this retrospective study. Patients with IS were compared to age-matched controls with normal sagittal spine MR. All subjects had T1-weighted spin-echo (500/20) and T2-weighted fast spin-echo (2000/90) sagittal cervical spine images at 1.5 T. Readers blinded to demographic data and study hypothesis measured anteroposterior diameters at each cervical level. The spinal canal diameters were compared with a Mann-Whitney U test. The overall difference was assessed with a Friedman test. Seventeen subjects were read by two reviewers to assess inter-rater reliability. Fifty IS patients with 50 age-matched controls were studied. IS subjects had one or more syrinxes varying from 1 to 19 spinal segments. Spinal canal diameters narrowed from C1 to C3 and then enlarged from C5 to C7 in both groups. Diameters from C2 to C4 were narrower in the IS group (p < 0.005) than in controls. The ratio of the C3 to the C7 diameters was also smaller (p = 0.004) in IS than controls. Collectively, the spinal canal diameters in the IS were significantly different from controls (Friedman test p < 0.0001). Patients with IS have abnormally narrow upper and mid cervical spinal canal diameters and greater positive tapering between C3 and C7. (orig.)

  1. Cervical spinal canal narrowing in idiopathic syringomyelia

    Energy Technology Data Exchange (ETDEWEB)

    Struck, Aaron F. [Massachusetts General Hospital, Department of Neurology, Boston, MA (United States); Carr, Carrie M. [Mayo Clinic, Department of Radiology, Rochester, MN (United States); Shah, Vinil [University of California San Francisco, Department of Radiology, San Francisco, CA (United States); Hesselink, John R. [University of California San Diego, Department of Radiology, San Diego, CA (United States); Haughton, Victor M. [University of Wisconsin, Department of Radiology, Madison, WI (United States)

    2016-08-15

    The cervical spine in Chiari I patient with syringomyelia has significantly different anteroposterior diameters than it does in Chiari I patients without syringomyelia. We tested the hypothesis that patients with idiopathic syringomyelia (IS) also have abnormal cervical spinal canal diameters. The finding in both groups may relate to the pathogenesis of syringomyelia. Local institutional review boards approved this retrospective study. Patients with IS were compared to age-matched controls with normal sagittal spine MR. All subjects had T1-weighted spin-echo (500/20) and T2-weighted fast spin-echo (2000/90) sagittal cervical spine images at 1.5 T. Readers blinded to demographic data and study hypothesis measured anteroposterior diameters at each cervical level. The spinal canal diameters were compared with a Mann-Whitney U test. The overall difference was assessed with a Friedman test. Seventeen subjects were read by two reviewers to assess inter-rater reliability. Fifty IS patients with 50 age-matched controls were studied. IS subjects had one or more syrinxes varying from 1 to 19 spinal segments. Spinal canal diameters narrowed from C1 to C3 and then enlarged from C5 to C7 in both groups. Diameters from C2 to C4 were narrower in the IS group (p < 0.005) than in controls. The ratio of the C3 to the C7 diameters was also smaller (p = 0.004) in IS than controls. Collectively, the spinal canal diameters in the IS were significantly different from controls (Friedman test p < 0.0001). Patients with IS have abnormally narrow upper and mid cervical spinal canal diameters and greater positive tapering between C3 and C7. (orig.)

  2. Analysis of velocity planning interpolation algorithm based on NURBS curve

    Science.gov (United States)

    Zhang, Wanjun; Gao, Shanping; Cheng, Xiyan; Zhang, Feng

    2017-04-01

    To reduce interpolation time and Max interpolation error in NURBS (Non-Uniform Rational B-Spline) inter-polation caused by planning Velocity. This paper proposed a velocity planning interpolation algorithm based on NURBS curve. Firstly, the second-order Taylor expansion is applied on the numerator in NURBS curve representation with parameter curve. Then, velocity planning interpolation algorithm can meet with NURBS curve interpolation. Finally, simulation results show that the proposed NURBS curve interpolator meet the high-speed and high-accuracy interpolation requirements of CNC systems. The interpolation of NURBS curve should be finished.

  3. Estimation of Typhoon Wind Hazard Curves for Nuclear Sites

    Energy Technology Data Exchange (ETDEWEB)

    Choun, Young-Sun; Kim, Min-Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    The intensity of such typhoons, which can influence the Korean Peninsula, is on an increasing trend owing to a rapid change of climate of the Northwest Pacific Ocean. Therefore, nuclear facilities should be prepared against future super-typhoons. Currently, the U.S. Nuclear Regulatory Commission requires that a new NPP should be designed to endure the design-basis hurricane wind speeds corresponding to an annual exceedance frequency of 10{sup -7} (return period of 10 million years). A typical technique used to estimate typhoon wind speeds is based on a sampling of the key parameters of typhoon wind models from the distribution functions fitting statistical distributions to the observation data. Thus, the estimated wind speeds for long return periods include an unavoidable uncertainty owing to a limited observation. This study estimates the typhoon wind speeds for nuclear sites using a Monte Carlo simulation, and derives wind hazard curves using a logic-tree framework to reduce the epistemic uncertainty. Typhoon wind speeds were estimated for different return periods through a Monte-Carlo simulation using the typhoon observation data, and the wind hazard curves were derived using a logic-tree framework for three nuclear sites. The hazard curves for the simulated and probable maximum winds were obtained. The mean hazard curves for the simulated and probable maximum winds can be used for the design and risk assessment of an NPP.

  4. File list: Oth.CDV.05.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.CDV.05.AllAg.Atrioventicular_canals mm9 TFs and others Cardiovascular Atrioventicular canals... SRX1271841 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.CDV.05.AllAg.Atrioventicular_canals.bed ...

  5. File list: Oth.CDV.20.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.CDV.20.AllAg.Atrioventicular_canals mm9 TFs and others Cardiovascular Atrioventicular canals... SRX1271841 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.CDV.20.AllAg.Atrioventicular_canals.bed ...

  6. File list: Oth.CDV.10.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.CDV.10.AllAg.Atrioventicular_canals mm9 TFs and others Cardiovascular Atrioventicular canals... SRX1271841 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.CDV.10.AllAg.Atrioventicular_canals.bed ...

  7. File list: Oth.CDV.50.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.CDV.50.AllAg.Atrioventicular_canals mm9 TFs and others Cardiovascular Atrioventicular canals... SRX1271841 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.CDV.50.AllAg.Atrioventicular_canals.bed ...

  8. First branchial cleft fistula associated with external auditory canal stenosis and middle ear cholesteatoma.

    Science.gov (United States)

    Abdollahi Fakhim, Shahin; Naderpoor, Masoud; Mousaviagdas, Mehrnoosh

    2014-10-01

    First branchial cleft anomalies manifest with duplication of the external auditory canal. This report features a rare case of microtia and congenital middle ear and canal cholesteatoma with first branchial fistula. External auditory canal stenosis was complicated by middle ear and external canal cholesteatoma, but branchial fistula, opening in the zygomatic root and a sinus in the helical root, may explain this feature. A canal wall down mastoidectomy with canaloplasty and wide meatoplasty was performed. The branchial cleft was excised through parotidectomy and facial nerve dissection. It should be considered that canal stenosis in such cases can induce cholesteatoma formation in the auditory canal and middle ear.

  9. Tullio phenomenon in superior semicircular canal dehiscence syndrome.

    Science.gov (United States)

    Basura, Gregory J; Cronin, Scott J; Heidenreich, Katherine D

    2014-03-18

    Tullio phenomenon refers to eye movements induced by sound.(1) This unusual examination finding may be seen in superior semicircular canal dehiscence (SSCD) syndrome.(2) This disorder is due to absent bone over the superior semicircular canal (figure). Patients complain of dizziness triggered by loud sound, aural fullness, autophony, and pulsatile tinnitus. When Tullio phenomenon exists in SSCD syndrome, the patient develops a mixed vertical-torsional nystagmus in which the slow phase rotates up and away from the affected ear (video on the Neurology® Web site at Neurology.org). This pattern of nystagmus aligns in the plane of the dehiscent semicircular canal and is due to excitation of its afferent nerves.

  10. The Melting Curve and Premelting of MgO

    OpenAIRE

    Cohen, R. E.; Weitz, J. S.

    1996-01-01

    The melting curve for MgO was obtained using molecular dynamics and a non-empirical, many-body potential. We also studied premelting effects by computing the dynamical structure factor in the crystal on approach to melting. The melting curve simulations were performed with periodic boundary conditions with cells up to 512 atoms using the ab-initio Variational Induced Breathing (VIB) model. The melting curve was obtained by computing $% \\Delta H_m$ and $\\Delta V_m$ and integrating the Clapeyro...

  11. Qualitative analysis of the Dix-Hallpike maneuver in multi-canal BPPV using a biomechanical model: Introduction of an expanded Dix-Hallpike maneuver for enhanced diagnosis of multi-canal BPPV

    Directory of Open Access Journals (Sweden)

    Henri Traboulsi

    2017-09-01

    Conclusion: The Dix–Hallpike maneuver may cause simultaneous movement of otoliths present in multiple canals and create an obstacle to accurate diagnosis in multi-canal BPPV. An expanded Dix-Hallpike maneuver is described which adds intermediate steps with the head positioned to the right and left in the horizontal position before head-hanging. This expanded maneuver has helped to isolate affected semi-circular canals for individual assessment in multiple canal BPPV.

  12. Combined Monte Carlo and path-integral method for simulated library of time-resolved reflectance curves from layered tissue models

    Science.gov (United States)

    Wilson, Robert H.; Vishwanath, Karthik; Mycek, Mary-Ann

    2009-02-01

    Monte Carlo (MC) simulations are considered the "gold standard" for mathematical description of photon transport in tissue, but they can require large computation times. Therefore, it is important to develop simple and efficient methods for accelerating MC simulations, especially when a large "library" of related simulations is needed. A semi-analytical method involving MC simulations and a path-integral (PI) based scaling technique generated time-resolved reflectance curves from layered tissue models. First, a zero-absorption MC simulation was run for a tissue model with fixed scattering properties in each layer. Then, a closed-form expression for the average classical path of a photon in tissue was used to determine the percentage of time that the photon spent in each layer, to create a weighted Beer-Lambert factor to scale the time-resolved reflectance of the simulated zero-absorption tissue model. This method is a unique alternative to other scaling techniques in that it does not require the path length or number of collisions of each photon to be stored during the initial simulation. Effects of various layer thicknesses and absorption and scattering coefficients on the accuracy of the method will be discussed.

  13. Management of foreign object in the root canal of central incisor tooth

    Directory of Open Access Journals (Sweden)

    Mothanna Alrahabi

    2014-01-01

    Full Text Available There are several reports describing the impaction of foreign objects into the exposed pulp chambers and canals by patients, especially children as they often have the habit of inserting foreign objects in the oral cavity. These objects will become a potent source of infection.This case report describes the retrieval of a foreign object impacted into the root canal of a 12-year-old male patient who was referred to the endodontic specialty clinic at Taibah University College of Dentistry. The patient′s chief complaint was a pain in the upper left central tooth. Clinical examination revealed a complicated enamel-dentin fracture with a large caries cavity. A periapical radiographic image showed a radiopaque object in the root canal system. Stainless steel Hedstrom files were used to retrieve the object from the canal. Following a proper cleaning and shaping of the root canal system, an intra-canal calcium hydroxide dressing was placed for 1 week. The root canal system was then filled with sealer and gutta-percha using the lateral compaction technique and the tooth received an aesthetic restoration.

  14. Rainfall - CN (Curve Number relationships in a tropical rainforest microbasin within the Panamá Canal watershed

    Directory of Open Access Journals (Sweden)

    José R. Fábrega D

    2012-01-01

    Full Text Available Relaciones de Precipitación (P y Número de Curva (CN para diferentesrangos de flujo base obtenidas dentro de la cuenca alta del Río Chagres fueron aplicadas a una microcuenca de 6.5 Ha localizada dentro de la cuenca del Canal de Panamá. Estas relaciones estiman valores de CN a partir de los datos de P empleando una ecuación establecida por Calvo et al (10. Esta ecuación usa k y CN∞ como parámetros de ajuste. Datos de precipitación/escorrentía de la microcuenca, colectados en un período de 6 meses fueron analizados. Estos análisis mostraron que los valores de CN en la microcuenca son más cercanos a los valores de CN predichos por la ecuación correspondiente al rango más bajo de los flujos base (14-42 m3/s de la cuenca alta del Río Chagres. Estos resultados se explican si consideramos no los valores absolutos del flujo base Qbase, sino los valores relativos de este parámetro con respecto al área de la cuenca bajo estudio.

  15. Effectiveness of EDTA as the irrigation solution to remove smear layer in root canal

    Directory of Open Access Journals (Sweden)

    Kurniasri Amas Achiar

    2009-07-01

    Full Text Available One of the objectives of successful endodontic treatment is the hermetic obturation of the root canal system. To achieve this, the root canal filling must seal the canal space both apically and coronally to prevent the ingress of microorganisms or tissue fluids into the canal space. Apical leakage is reported a common reason for the clinical failure of endodontic therapy. Leakage through an obturated root canal is expected to take place at interfaces between sealer and dentin or sealer and gutta-percha, or through voids within the sealer. Hence, the sealing quality of root canal filling depends much on the sealing ability of the sealer. Therefore, anything that may influence the adaptation of the root filling to the canal wall is can determine the degree and the extent of leakage, and ultimately the prognosis of the endodontic therapy. In endodontic therapy, the smear layer formation results from root canal preparation and may influence the effective seal of the root canal system. The smear layer formation is mainly composed of inorganic components (dentin debris and organic materials, such as pulp tissue remnant, bacteria, and blood cells. Removal of the smear layer from the root canal walls before the obturation can reduce the leakage of root canal sealer. To remove the smear layer use 10 ml 17% EDTA followed by 10 ml of 5.25% NaOCl as irrigating solution. This paper discribe about how the effectivity of EDTA as irigating solution to remove the smear layer especially in the apical root canal with many lateral canal to reduce the apical leakage.

  16. Magnetic resonance imaging anatomy of the anal canal

    International Nuclear Information System (INIS)

    Kashyap, P.; Bates, N.

    2004-01-01

    The anatomy of the anal canal is complex but well demonstrated by MRI. Understanding the anatomy is a prerequisite for determining the true site and the extent of pathology, especially for surgical workup. In this article, the MRI anatomy of the anal canal has been displayed using highlighted MRI images and line diagrams. Copyright (2004) Blackwell Science Pty Ltd

  17. Nodular Fasciitis of External Auditory Canal

    Directory of Open Access Journals (Sweden)

    Jihyun Ahn

    2016-09-01

    Full Text Available Nodular fasciitis is a pseudosarcomatous reactive process composed of fibroblasts and myofibroblasts, and it is most common in the upper extremities. Nodular fasciitis of the external auditory canal is rare. To the best of our knowledge, less than 20 cases have been reported to date. We present a case of nodular fasciitis arising in the cartilaginous part of the external auditory canal. A 19-year-old man complained of an auricular mass with pruritus. Computed tomography showed a 1.7 cm sized soft tissue mass in the right external auditory canal, and total excision was performed. Histologic examination revealed spindle or stellate cells proliferation in a fascicular and storiform pattern. Lymphoid cells and erythrocytes were intermixed with tumor cells. The stroma was myxoid to hyalinized with a few microcysts. The tumor cells were immunoreactive for smooth muscle actin, but not for desmin, caldesmon, CD34, S-100, anaplastic lymphoma kinase, and cytokeratin. The patient has been doing well during the 1 year follow-up period.

  18. Incisive canal deflation for correct implant placement: case report.

    Science.gov (United States)

    Spin-Neto, Rubens; Bedran, Telma Blanca Lombardo; de Paula, Wagner Nunes; de Freitas, Rubens Moreno; de Oliveira Ramalho, Lizeti Toledo; Marcantonio, Elcio

    2009-12-01

    This article is a case report of a patient in whom the prosthetic planning indicated the necessity of an incisive canal deflation for the correct installation of an implant that is to be osseointegrated. In the reopening phase after the bone graft installation, the incisive canal deflation (biopsy of its content) was done and titanium implants were installed with one of them invading the anatomical space occupied previously by the incisive canal. The biopsy analysis showed fragments of the incisive artery and nerve, which are responsible for the anterior upper-tooth pulp, the periodontium vascularization and the innervation. From the anastomosis present along with other structures allied with the absence of teeth in the region, there was no detriment to the patient caused by the deflation. Incisive canal deflation is a viable technique in implantology. It can permit ideal prosthetic planning with no detriment to the patient.

  19. First Branchial Cleft Fistula Associated with External Auditory Canal Stenosis and Middle Ear Cholesteatoma

    Science.gov (United States)

    Abdollahi fakhim, Shahin; Naderpoor, Masoud; Mousaviagdas, Mehrnoosh

    2014-01-01

    Introduction: First branchial cleft anomalies manifest with duplication of the external auditory canal. Case Report: This report features a rare case of microtia and congenital middle ear and canal cholesteatoma with first branchial fistula. External auditory canal stenosis was complicated by middle ear and external canal cholesteatoma, but branchial fistula, opening in the zygomatic root and a sinus in the helical root, may explain this feature. A canal wall down mastoidectomy with canaloplasty and wide meatoplasty was performed. The branchial cleft was excised through parotidectomy and facial nerve dissection. Conclusion: It should be considered that canal stenosis in such cases can induce cholesteatoma formation in the auditory canal and middle ear. PMID:25320705

  20. First Branchial Cleft Fistula Associated with External Auditory Canal Stenosis and Middle Ear Cholesteatoma

    Directory of Open Access Journals (Sweden)

    shahin abdollahi fakhim

    2014-10-01

    Full Text Available Introduction: First branchial cleft anomalies manifest with duplication of the external auditory canal.   Case Report: This report features a rare case of microtia and congenital middle ear and canal cholesteatoma with first branchial fistula. External auditory canal stenosis was complicated by middle ear and external canal cholesteatoma, but branchial fistula, opening in the zygomatic root and a sinus in the helical root, may explain this feature. A canal wall down mastoidectomy with canaloplasty and wide meatoplasty was performed. The branchial cleft was excised through parotidectomy and facial nerve dissection.   Conclusion:  It should be considered that canal stenosis in such cases can induce cholesteatoma formation in the auditory canal and middle ear.

  1. New configuration factors for curved surfaces

    International Nuclear Information System (INIS)

    Cabeza-Lainez, Jose M.; Pulido-Arcas, Jesus A.

    2013-01-01

    Curved surfaces have not been thoroughly considered in radiative transfer analysis mainly due to the difficulties arisen in the integration process and perhaps because of the lack of spatial vision of the researchers. It is a fact, especially for architectural lighting, that when concave geometries appear inside a curved space, they are mostly avoided. In this way, a vast repertoire of significant forms is neglected and energy waste is evident. Starting from the properties of volumes enclosed by the minimum number of surfaces, the authors formulate, with little calculus, new simple laws, which enable them to discover a set of configuration factors for caps and various segments of the sphere. The procedure is subsequently extended to previously unimagined surfaces as the paraboloid, the ellipsoid or the cone. Appropriate combination of the said forms with right truncated cones produces several complex volumes, often used in architectural and engineering creations and whose radiative performance could not be accurately predicted for decades. To complete the research, a new method for determining interreflections in curved volumes is also presented. Radiative transfer simulation benefits from these findings, as the simplicity of the results has led the authors to create innovative software more efficient for design and evaluation and applicable to emerging fields like LED lighting. -- Highlights: ► Friendly revision of fundamentals of radiative transfer. ► New configuration factors for curved surfaces obtained without calculus. ► New method for interreflections in curved geometries. ► Enhanced simulation algorithms. ► Fast comparison of radiative performances of surfaces

  2. Experimental circumferential canaloplasty with a new Schlemm canal microcatheter

    Directory of Open Access Journals (Sweden)

    Mao-Song Xie

    2018-01-01

    Full Text Available AIM: To present a new, simple, inexpensive Schlemm canal microcatheter for circumferential canaloplasty in a rabbit model. METHODS: A rabbit glaucoma animal model was established by intravitreal injection of triamcinolone acetonide. Circumferential canaloplasty with a new Schlemm canal microcatheter (patent license number: 201220029850.0 was performed. The Schlemm canal microcatheter was composed of microcatheter wall and lumen. The wall was made of high refractive index plastic optical fiber that could be attached to an illuminant so that the whole lighted microcatheter was visible during circumferential canaloplasty. The lumen could be attached to an injector for injection of viscoelastic during catheterization. Rabbits were divided randomly into the control, model and treatment groups. Intraocular pressure (IOP was measured with a Tono-pen tonometer pre-operation and 3, 7, 14, 21 and 28d post-operation. Ultrasound biomicroscopy was performed to visualize the Schlemm canal microcatheter in the Schlemm canal and the sclera pool. RESULTS: The Schlemm canal microcatheter could be used to perform circumferential canaloplasty in the rabbit glaucoma animal model. IOP was lower in the treatment group than that in the model group 3, 7, 14 and 28d after operation. There were no significant differences in IOP between the control group and treatment group. The differences among the three groups were statistically significant (3d: F=41.985, P<0.001; 7d: F=65.696, P<0.001; 14d: F=114.599, P<0.001; 28d: F=55.006, P<0.001. CONCLUSION: Circumferential canaloplasty is safe and effective in control of experimental glaucoma model in rabbits.

  3. Roentgenographic study of the mandibular canal

    International Nuclear Information System (INIS)

    Ahn, Hyung Kyu

    1980-01-01

    The mandibular canal must be considered carefully during the surgical treatment, especially surgical extraction of the impacted tooth and intraosseous implant, because it contains the important inferior alveolar nerve and vessels. The author investigated the curvature of the mandibular canal and its relation to the mandibular molars and positional relation between the mental foramen and the mandibular premolars in orthopantomogram. The materials consisted of 441 orthopantomograms divided four groups; Group I consisted of 56 males and 44 females from 1 to 6 years of age, Group II consisted of 58 males and 45 females from 7 to 12 years of age, Group III consisted of 65 males and 33 females from 13 to 18 years of age, Group IV consisted of 86 males and 54 females over 19 years of age. The results were as followings; 1. The curvature of mandibular canal was 144.50 .deg. in Group II, 148.11 .deg. in Group III, 147.33 .deg. in Group IV. 2. The curvature of mandibular canal was located most frequently on the area between mandibular 1st molar and mandibular 2nd molar in Group I (42%) and on the mandibular 2nd molar area in Group II (54%), Group III (59%), Group IV (53%). 3. The position of mental foramen was most frequently below the mandibular 1st premolar in Group I (58%), between the mandibular 1st premolar and the 2nd premolar in Group II (62%), Group III (47%), and below the mandibular 2nd premolar in Group IV (58%).

  4. Root anatomy and canal configuration of the permanent mandibular first molar: a systematic review.

    Science.gov (United States)

    de Pablo, Oliver Valencia; Estevez, Roberto; Péix Sánchez, Manuel; Heilborn, Carlos; Cohenca, Nestor

    2010-12-01

    The main goal of endodontic therapy is to prevent or heal apical periodontitis. However, root canal anatomy might present a clinical challenge directly related to the treatment outcome. The purpose of this study was to review published literature related to root anatomy and root canal configuration of the permanent mandibular first molar. An exhaustive search was undertaken to identify published literature related to the root anatomy and root canal morphology of the permanent mandibular first molar by using key words. The search of the MEDLINE database included all publications from 1966-May 2010. Selected articles were then obtained and reviewed. Data evaluated and summarized in the data sheet included methodology, population, number of teeth per study (power), number of root canals, type of root canal configuration, and identification of number of apical foramina. Forty-one studies were identified including a total of 18,781 teeth. The incidence of a third root was 13% and was strongly correlated with the ethnicity of the studied population. Three canals were present in 61.3%, 4 canals in 35.7%, and 5 canals in approximately 1%. Root canal configuration of the mesial root revealed 2 canals in 94.4% and 3 canals in 2.3%. The most common canal system configuration was Vertucci type IV (52.3%), followed by type II (35%). Root canal configuration of the distal root revealed type I configuration in 62.7%, followed by types II (14.5%) and IV (12.4%). The presence of isthmus communications averaged 54.8% on the mesial and 20.2% on the distal root. The number of roots on the mandibular first molar is directly related to ethnicity. Root canal morphology and configuration might present the clinician with a complex anatomy requiring more diagnostic approaches, access modifications, and clinical skills to successfully localize, negotiate, disinfect, and seal the root canal system. Crown Copyright © 2010. Published by Elsevier Inc. All rights reserved.

  5. Unusual root canal morphology of mandibular second premolars: A case series and review

    Directory of Open Access Journals (Sweden)

    Snehal Sonarkar

    2017-01-01

    Full Text Available Mandibular second premolars (MSPs have varied anatomy ranging from 1 to 3 roots and 1–5 canals. Successful endodontic treatment is achieved by proper access opening, cleaning, and shaping and three-dimensional obturation. This case series describes five cases in which MSPs have been diagnosed with aberrant canal system. The Case 1 and 5 has one root with Vertucci's Type V canal configuration. The Case 2 has two roots with two canals, the Case 3 has one root with Vertucci's Type IV canal configuration, whereas the Case 4 has three roots with three canals. This case series also describes a classification for describing the root configuration. The clinical implications of this paper are first to reach at appropriate diagnosis of canal system using diagnostic aids (angulated radiographs and dental operating microscope. Second, to use advanced endodontic instruments for achieving successful endodontic therapy (NiTi rotary instruments.

  6. Root Canal Configuration of Maxillary First Permanent Molars in an Iranian Population

    Directory of Open Access Journals (Sweden)

    Saeed Rahimi

    2007-06-01

    Full Text Available

    Background and aims. It is critical to have a proper knowledge of the normal anatomy of the pulp and its variations for the success of endodontic treatment. The purpose of this study was to investigate variations in the root canal system of maxillary first permanent molars in an Iranian population.

    Materials and methods. In this study, 137 maxillary first molars were decalcified, dye-injected, cleared and studied.

    Results. The results demonstrated that 37.96% of the maxillary first molars under study had three canals, 58.4% had four canals and 3.64% had five canals.

    Conclusion. According to the results of this study and considering variations in the root canal systems of maxillary first molars, it seems that great care should be taken in the root canal treatment of these teeth.

  7. Incidence of apical root cracks and apical dentinal detachments after canal preparation with hand and rotary files at different instrumentation lengths

    NARCIS (Netherlands)

    Liu, R.; Kaiwar, A.; Shemesh, H.; Wesselink, P.R.; Hou, B.; Wu, M.K.

    2013-01-01

    Introduction The aim of this study was to compare the incidence of apical root cracks and dentinal detachments after canal preparation with hand and rotary files at different instrumentation lengths. Methods Two hundred forty mandibular incisors were mounted in resin blocks with simulated

  8. Anatomy and morphology of the nasopalatine canal using cone-beam computed tomography

    International Nuclear Information System (INIS)

    Thakur, Arpita Rai; Burde, Krishna; Guttai, Kruthika; Naikmasu, Venkatesh

    2013-01-01

    This study was performed to evaluate the general anatomy and morphology of the nasopalatine canal using cone-beam computed tomography (CBCT) and to determine the human anatomic variability of the nasopalatine canal in relation to age and gender. The study included 100 subjects aged between 20 and 86 years who were divided into the following 3 groups: 1) 20-34 years old; 2) 35-49 years old; 3) ≥50 years old. The subjects were equally distributed between the genders. CBCT was performed using a standard exposure and patient positioning protocol. The data of the CBCT images were sliced in three dimensions. Image planes on the three axes (X, Y, and Z) were sequentially analyzed for the location, morphology and dimensions of the nasopalatine canal by two independent observers. The correlation of age and gender with all the variables was evaluated. The present study did not reveal statistically significant differences in the number of openings at the nasal fossa; diameter of the nasal fossa openings; diameter of the incisive fossa; shape, curvature, and angulation of the canal as viewed in the sagittal sections; antero-posterior dimensions and length of the canal in the sagittal sections; or the level of division of the canal in the coronal plane by age. However, males and females showed significant differences in the length of the canal in the sagittal sections and level of the division of the canal in the coronal plane. The present study highlighted important variability observed in the anatomy and morphology of the nasopalatine canal.

  9. Anatomy and morphology of the nasopalatine canal using cone-beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Arpita Rai [Dept. of Oral Medicine and Radiology, Faculty of Dentistry, Jamia Millia Islamia University, New Delhi (India); Burde, Krishna; Guttai, Kruthika; Naikmasu, Venkatesh [Dept. of Oral Medicine and Radiology, S.D.M. College of Dental Sciences and Hospital, Dharwad (India)

    2013-12-15

    This study was performed to evaluate the general anatomy and morphology of the nasopalatine canal using cone-beam computed tomography (CBCT) and to determine the human anatomic variability of the nasopalatine canal in relation to age and gender. The study included 100 subjects aged between 20 and 86 years who were divided into the following 3 groups: 1) 20-34 years old; 2) 35-49 years old; 3) ≥50 years old. The subjects were equally distributed between the genders. CBCT was performed using a standard exposure and patient positioning protocol. The data of the CBCT images were sliced in three dimensions. Image planes on the three axes (X, Y, and Z) were sequentially analyzed for the location, morphology and dimensions of the nasopalatine canal by two independent observers. The correlation of age and gender with all the variables was evaluated. The present study did not reveal statistically significant differences in the number of openings at the nasal fossa; diameter of the nasal fossa openings; diameter of the incisive fossa; shape, curvature, and angulation of the canal as viewed in the sagittal sections; antero-posterior dimensions and length of the canal in the sagittal sections; or the level of division of the canal in the coronal plane by age. However, males and females showed significant differences in the length of the canal in the sagittal sections and level of the division of the canal in the coronal plane. The present study highlighted important variability observed in the anatomy and morphology of the nasopalatine canal.

  10. Anomalous facial nerve canal with cochlear malformations.

    Science.gov (United States)

    Romo, L V; Curtin, H D

    2001-05-01

    Anteromedial "migration" of the first segment of the facial nerve canal has been previously identified in a patient with a non-Mondini-type cochlear malformation. In this study, several patients with the same facial nerve canal anomaly were reviewed to assess for the association and type of cochlear malformation. CT scans of the temporal bone of 15 patients with anteromedial migration of the first segment of the facial nerve canal were collected from routine departmental examinations. In seven patients, the anomalous course was bilateral, for a total of 22 cases. The migration was graded relative to normal as either mild/moderate or pronounced. The cochlea in each of these cases was examined for the presence and size of the basilar, second, and apical turns. The turns were either absent, small, normal, or enlarged. The CT scans of five patients with eight Mondini malformations were examined for comparison. The degree of the facial nerve migration was pronounced in nine cases and mild/moderate in 13. All 22 of these cases had associated cochlear abnormalities of the non-Mondini variety. These included common cavity anomalies with lack of definition between the cochlea and vestibule (five cases), cochleae with enlarged basilar turns and absent second or third turns (five cases), and cochleae with small or normal basilar turns with small or absent second or third turns (12 cases). None of the patients with Mondini-type cochlear malformations had anteromedial migration of the facial nerve canal. Anteromedial migration of the facial nerve canal occurs in association with some cochlear malformations. It did not occur in association with the Mondini malformations. A cochlea with a Mondini malformation, being similar in size to a normal cochlea, may physically prohibit such a deviation in course.

  11. Pollution of Lahore canal water in the city premises

    International Nuclear Information System (INIS)

    Hussain, Z.; Baig, M.A.

    1997-01-01

    Water contamination is one of the major environmental pollution problems facing Pakistan because it has a direct impact on the health of human beings and crops. Lahore Canal water is being used both for irrigation and a source of ground water recharge. For the best use of this water, extent of pollution and its effect on soil hydraulic properties needs to be studied. For this purpose, water samples from twenty three sites and soil samples from three sites were collected along the Canal within the city limits of Lahore. The survey of the area from Jallo Park to Mall Road, show that all the abadies/colonies and industries situated on both sides of the canal dump their waste water and garbage in to canal. This result in increase of salinity as well as BOD and COD values which were found maximum at the locations of Herbuns Pura, Mughal Pura Dharam Pura, and Thoker Niaz Baig. (authors)

  12. CT of the external auditory canal: Correlation with clinical otoscopy

    International Nuclear Information System (INIS)

    Shankar, L.; Hawke, M.; Leekam, R.N.

    1987-01-01

    CT is the modality of choice in the assessment of external auditory canal abnormalities. Disorders of the complex structures within the ear that may be difficult to define clinically are well visualized on high-resolution CT. This exhibit illustrates various external auditory canal abnormalities and correlates these with color illustrations from clinical otoscopy. Congenital lesions of the external auditory canal - microtia, temporo-bandibular joint herniation, and fistulas - and various acquired lesions - traumatic, inflammatory, and neoplastic - are reviewed in this exhibit

  13. Variation of Bragg curve characteristic induced by changing the position of inhomogeneous material: Geant4 simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Park, So-Hyun; Jung, Won-Gyun; Suh, Tae-Suk [Catholic University, Seoul (Korea, Republic of); Jang, Hong-Seok; Choi, Byeong-Oak [Seoul St. Mary' s Hospital, Seoul (Korea, Republic of); Rah, Jeong-Eun; Park, Sun-Gyong; Lee, Se-Byeong [National Cancer Center, Ilsan (Korea, Republic of)

    2011-02-15

    When proton beam passes through the human body, the stopping power and the depth-dose distribution of the proton are influenced by the relative location among adjacent materials or the difference in material conditions. Our study demonstrates the effect of inhomogeneous materials placed in the Plateau and Bragg peak regions of the Bragg curve in water. We evaluated the Bragg peak position, range, penumbra and integrated doses by using the Geant4 simulation toolkit. The positions of inhomogeneities were selected as the proximal 36% and 50% points of the maximum dose, which indicates the location at entrance regions of the Plateau and the Bragg peak, respectively. Bone (density {rho} = 1.85 g/cm{sup 3}) and adipose tissue (density {rho} = 0.92 g/cm{sup 3}) were selected as inhomogeneous materials. The thickness of each material was varied by 0.1 cm between 0.1 cm and 1.0 cm. In addition, the initial energy of the proton beam was changed in 30 MeV steps between 108 MeV and 220 MeV. The effects of inhomogeneous conditions were performed for various parameters: Bragg peak position, range, penumbra width, full width at half maximum and dose of Bragg curve. A dose perturbation was observed in the region of the Bragg peak and inhomogeneous material, especially, When the bone equivalent material was inserted within the Bragg curve. However, there were no significant variations in the other parameters, except for the dose perturbation depending on the inserted location of each material. This study shows the characteristic changes in the Bragg curve due to inhomogeneous materials.

  14. Incidence of two canals in extracted mandibular incisors teeth of Saudi Arabian samples

    Directory of Open Access Journals (Sweden)

    Khalid S Al-Fouzan

    2012-01-01

    Full Text Available Aim: The purpose of this in vitro study is to provide clinical data on the presence of the second canal in mandibular incisor teeth of Saudi Arabian Samples. Materials and Methods: Eighty extracted human mandibular incisors were collected from Saudi patients. The teeth were accessed by small round bur then placed in 5.25% sodium hypochlorite for 24 hours to dissolve the organic debris. Indian ink was injected inside the root canal systems under negative pressure. The teeth were decalcified in 5% nitric acid for three days then dehydrated in different concentrations of ethyl alcohol. Following the decalcification process, the teeth were cleared in methyl salicylate and evaluated according to Vertucci′s classification. Result: Fifty six of both mandibular central and lateral incisor teeth (70% had type I canal configuration (one main canal and one main apical foramen, while the remaining 30% of the sample (24 teeth had a type III canal configuration (two separate canals and merged into one canal before exiting the tooth through single apical foramen. Conclusion : The incidence of two canals in mandibular incisor teeth is about one third of the examined Saudi Arabian samples with no difference between the centrals and laterals. The clinician should deal with these teeth as if they have two canals unless it is proved otherwise.

  15. AFSC/ABL: Lynn Canal Echo-Integrated Trawl Surveys, 2001-2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The acoustic trawl database for Lynn Canals echo-trawl survey was conducted from 2001 to 2004 throughout southern Lynn Canal in southeast Alaska. Acoustic surveys...

  16. EL TRANSPORTE DE CANTIDAD DE MOVIMIENTO EN CANALES

    Directory of Open Access Journals (Sweden)

    Francisco Jaime Mejía

    Full Text Available Este artículo tiene por objeto aplicar el transporte de cantidad de movimiento al flujo en canales como una metodología independiente de otros principios físicos. Así se subsana una carencia de la literatura técnica cuando aborda la interpretación adicional de fenómenos hidráulicos que habitualmente se tratan desde la conservación de la energía. Concluye acerca del comportamiento de la profundidad de flujo en un canal ante diversas condiciones de flujo o variaciones de la profundidad o en presencia de controles hidráulicos. Con la ayuda de la ecuación de transporte de cantidad de movimiento a lo largo de un canal se interpreta el comportamiento del tirante hidráulico en flujo uniforme, en flujo no uniforme con variación gradual y en algunos fenómenos locales de flujo rápidamente variado como ocurre en las transiciones y en el resalto hidráulico. Se obtienen las ecuaciones del resalto hidráulico para calcular la profundidad inicial y secuente, conocida una de las dos, en diversas secciones transversales del canal.

  17. Spectral optimization simulation of white light based on the photopic eye-sensitivity curve

    International Nuclear Information System (INIS)

    Dai, Qi; Hao, Luoxi; Lin, Yi; Cui, Zhe

    2016-01-01

    Spectral optimization simulation of white light is studied to boost maximum attainable luminous efficacy of radiation at high color-rendering index (CRI) and various color temperatures. The photopic eye-sensitivity curve V(λ) is utilized as the dominant portion of white light spectra. Emission spectra of a blue InGaN light-emitting diode (LED) and a red AlInGaP LED are added to the spectrum of V(λ) to match white color coordinates. It is demonstrated that at the condition of color temperature from 2500 K to 6500 K and CRI above 90, such white sources can achieve spectral efficacy of 330–390 lm/W, which is higher than the previously reported theoretical maximum values. We show that this eye-sensitivity-based approach also has advantages on component energy conversion efficiency compared with previously reported optimization solutions

  18. Spectral optimization simulation of white light based on the photopic eye-sensitivity curve

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Qi, E-mail: qidai@tongji.edu.cn [College of Architecture and Urban Planning, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Institute for Advanced Study, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Key Laboratory of Ecology and Energy-saving Study of Dense Habitat (Tongji University), Ministry of Education, 1239 Siping Road, Shanghai 200092 (China); Hao, Luoxi; Lin, Yi; Cui, Zhe [College of Architecture and Urban Planning, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Key Laboratory of Ecology and Energy-saving Study of Dense Habitat (Tongji University), Ministry of Education, 1239 Siping Road, Shanghai 200092 (China)

    2016-02-07

    Spectral optimization simulation of white light is studied to boost maximum attainable luminous efficacy of radiation at high color-rendering index (CRI) and various color temperatures. The photopic eye-sensitivity curve V(λ) is utilized as the dominant portion of white light spectra. Emission spectra of a blue InGaN light-emitting diode (LED) and a red AlInGaP LED are added to the spectrum of V(λ) to match white color coordinates. It is demonstrated that at the condition of color temperature from 2500 K to 6500 K and CRI above 90, such white sources can achieve spectral efficacy of 330–390 lm/W, which is higher than the previously reported theoretical maximum values. We show that this eye-sensitivity-based approach also has advantages on component energy conversion efficiency compared with previously reported optimization solutions.

  19. Treatment of Two Canals in All Mandibular Incisor Teeth in the Same Patient

    Directory of Open Access Journals (Sweden)

    Vandana B. Kokane

    2014-01-01

    Full Text Available The main reason for unfavourable outcome in endodontic treatment of mandibular incisor is the inability to detect the presence of second canal. Pain even after extirpation of complete pulp tissue from root canal of vital teeth is the main indication of hidden canals. The present case report is also on pain because of another neglected canal in all mandibular incisors in the same patient.

  20. Determination of electron clinical spectra from percentage depth dose (PDD) curves by classical simulated annealing method

    International Nuclear Information System (INIS)

    Visbal, Jorge H. Wilches; Costa, Alessandro M.

    2016-01-01

    Percentage depth dose of electron beams represents an important item of data in radiation therapy treatment since it describes the dosimetric properties of these. Using an accurate transport theory, or the Monte Carlo method, has been shown obvious differences between the dose distribution of electron beams of a clinical accelerator in a water simulator object and the dose distribution of monoenergetic electrons of nominal energy of the clinical accelerator in water. In radiotherapy, the electron spectra should be considered to improve the accuracy of dose calculation since the shape of PDP curve depends of way how radiation particles deposit their energy in patient/phantom, that is, the spectrum. Exist three principal approaches to obtain electron energy spectra from central PDP: Monte Carlo Method, Direct Measurement and Inverse Reconstruction. In this work it will be presented the Simulated Annealing method as a practical, reliable and simple approach of inverse reconstruction as being an optimal alternative to other options. (author)

  1. Extracting Environmental Benefits from a New Canal in Nicaragua: Lessons from Panama.

    Directory of Open Access Journals (Sweden)

    Richard Condit

    2015-07-01

    Full Text Available Biologists have raised objections to a new canal in Nicaragua, but in this Essay I argue that dire predictions of environmental catastrophe are exaggerated. I present an alternative view based on my research experience in Panama, where Canal operations foster forest conservation. Currently in Nicaragua, the rate of forest loss is so rapid that the canal cannot make it worse. Rather, I contend, adoption of international standards in canal construction could lead to net environmental and social benefits for the country.

  2. Continuous Adductor Canal Blocks

    DEFF Research Database (Denmark)

    Monahan, Amanda M; Sztain, Jacklynn F; Khatibi, Bahareh

    2016-01-01

    on cutaneous knee sensation in volunteers. METHODS: Bilateral adductor canal catheters were inserted in 24 volunteers followed by ropivacaine 0.2% administration for 8 hours. One limb of each subject was assigned randomly to a continuous infusion (8 mL/h) or automated hourly boluses (8 m...

  3. The width of the incisive canal and labial alveolar bone of the incisive canal: an assessment on CT images

    International Nuclear Information System (INIS)

    Roh, Yang Gyun; Jang, Hyun Seon; Kim, Byung Ock; Kim, Jin Soo

    2006-01-01

    To assess the width of the labial alveolar bone of the incisive canal and the width of the incisive canal on spiral computed tomographic images of the anterior portion of the maxilla. Study materials included 38 CT scans taken for preoperative planning of implant placement. Axial cross-sectioned image entirely showing the incisive canal at an orifice to the oral cavity, middle portion, and an orifice to the nasal cavity and the diameter of the incisive canal at the middle portion were determined by two specialist using Digora for Windows 2.1. The statistical analyses were carried out using SPSS 12.0.1. When the maxillary central incisors remained, the mean labial alveolar bone width were 6.81±1.41 mm, 6.46±1.33 mm, and 7.91±1.33 mm. When the maxillary central incisors were missed the mean width were 5.42±2.20 mm, 6.23±2.29 mm, and 7.89±2.13 mm. The labial alveolar bone width at middle portion and an orifice to the nasal cavity were of no statistical significant difference according to presence of the maxillary central incisors (P>0.05). The width between oral cavity and nasal cavity, middle portion and to masal cavity revealed statistically significant difference (P<0.05)

  4. An experimental study on the computed tomography of the cervical spinal canal

    International Nuclear Information System (INIS)

    Wakabayashi, Tsuguru

    1980-01-01

    A study was carried out to investigate how accurately CT could delineate the vertebral canal, vertebral body, lamina, intervertebral foramen and transverse process, and which factor influences the size of the vertebral canal, using cervical vertebrae obtained from four cadavers and one skeleton. EMI CT 5005 scanner was used. CT picture depicted accurate shapes of the vertebral canal, body and transverse process. The sagittal diameter of the vertebral canal of CT picture varied by various conditions, such as difference of scanning chance, scanning angle, window width and level, but variations due to different absorption coefficients of the bone surrounding the vertebral canal were negligible. It was most significantly changed by scanning angle. Permissible scanning angle was within 5 0 , and morphological findings were not influenced up to 15 0 . The size of the vertebral canal was most accurately measured under the condition of 400 in width and 250 in level. The optimal condition for delineation of the spine seemed to be 400 in width and 100 - 150 in level. Under the condition at width 400 and level 100, the vertebral canal was delineated narrower by an average 0.6 mm and 0.2 mm in the sagittal and transverse diameter respectively. In CT picture of the imitational ossified posterior Longitudinal ligament made of plastic and alginate, the average narrowing rate of the vertebral canal was 4.4% greater than the one obtained by lateral view of radiograph, but both correlated well with each other. The narrowing rate of the vertebral canal by CT tended to increase in proportion to the increase in scanning angle. (J.P.N.)

  5. Root canal debris removal using different irrigating needles: An SEM study

    Directory of Open Access Journals (Sweden)

    Sheetal Ghivari

    2011-01-01

    Full Text Available Aim: This study was carried out to compare the efficacy of three irrigating needle designs in removal of debris from different parts of the root canal. Materials and Methods: Thirty human maxillary canines were prepared using HERO Shaper rotary system and irrigated with 1 ml of 5.25% sodium hypochlorite (NaOCl after each instrument change. Three 25-gauge irrigation needle designs - brush-covered Navi Tip FX (Group I, side-vented needle RC Twents (Group II and single-beveled (Group III irrigating needles - were tested for their efficiency in debris removal in three different parts of the root canal (n=10 canals per group. Following instrumentation, the roots were vertically sectioned and divided into coronal, middle and apical thirds for observation under scanning electron microscope (×200 magnification. Debris on the canal wall was evaluated by using a four-scale scoring system described by Paque and his co-workers. Results: The canals irrigated with brush-covered needle Navi Tip FX (Group I showed lower average debris score, indicating greater removal of debris in coronal third as compared to middle and apical thirds, whereas the canals irrigated with side-vented needle (Group II and single-beveled needle (Group III exhibited lower average score in the middle third than coronal and apical thirds. All the three needle designs exhibited higher debris score in apical third of the root canal. Tukey multiple comparisons test was applied at a significance level of P>0.05. A statistically significant difference (P<0.05 was observed in the debris removal in the coronal and middle thirds of root canals irrigated with brush-covered Navi Tip FX (Group I and side-vented (Group II needles, respectively, when compared with other needle design groups. Conclusion: Within the limitations of this study, it can be concluded that all the needle designs tested were effective in certain regions of the root canal with apical third uncleaned. Side-vented needle by

  6. Estresse crônico melhora a função miocárdica sem alterar a atividade do canal-L para Ca+2 em ratos

    Directory of Open Access Journals (Sweden)

    Thiago Bruder-Nascimento

    2012-10-01

    Full Text Available FUNDAMENTO: O estresse crônico está associado à remodelação cardíaca; entretanto, os mecanismos permanecem a ser descobertos. OBJETIVO: A proposta deste estudo foi testar a hipótese de que o estresse crônico promove disfunção cardíaca associada a depressão da atividade do canal-L para Ca2+. M MÉTODOS: Ratos Wistar machos com 30 dias de idade (70 - 100 g foram distribuídos dentro de dois grupos: controle (C e estresse crônico (St. O estresse consistiu na imobilização durante 15 semanas, cinco vezes por semana, 1 h por dia. A função cardíaca foi avaliada pela performance do ventrículo esquerdo por meio do ecocardiograma e pelo músculo papilar ventricular isolado. A função do músculo papilar foi avaliada em condição basal e com manobras inotrópicas, como: pós-pausa e elevação na concentração extracelular de Ca2+, na presença ou ausência de um bloqueador específico de canal-L para Ca2+. RESULTADOS: O estresse ficou caracterizado por hipertrofia das glândulas adrenais, aumento nos níveis de corticosterona circulante e por hipertensão arterial. Ainda, o estresse crônico gerou hipertrofia ventricular esquerda. O estresse crônico foi capaz de melhorar a resposta no músculo papilar para manobras inotrópicas positivas. A melhora de função não esteve associada com o canal-L para Ca2+. CONCLUSÃO: O estresse produziu hipertrofia cardíaca; entretanto, nos estudos de músculo papilar isolado, as manobras inotrópicas positivas potencializaram a função cardíaca em ratos estressados, sem o envolvimento do canal-L para Ca2+. Assim os mecanismos responsáveis permanecem incertos para alterações no influxo de Ca2+.

  7. Spinal canal stenosis; Spinalkanalstenose

    Energy Technology Data Exchange (ETDEWEB)

    Papanagiotou, P.; Boutchakova, M. [Klinikum Bremen-Mitte/Bremen-Ost, Klinik fuer Diagnostische und Interventionelle Neuroradiologie, Bremen (Germany)

    2014-11-15

    Spinal stenosis is a narrowing of the spinal canal by a combination of bone and soft tissues, which can lead to mechanical compression of spinal nerve roots or the dural sac. The lumbal spinal compression of these nerve roots can be symptomatic, resulting in weakness, reflex alterations, gait disturbances, bowel or bladder dysfunction, motor and sensory changes, radicular pain or atypical leg pain and neurogenic claudication. The anatomical presence of spinal canal stenosis is confirmed radiologically with computerized tomography, myelography or magnetic resonance imaging and play a decisive role in optimal patient-oriented therapy decision-making. (orig.) [German] Die Spinalkanalstenose ist eine umschriebene, knoechern-ligamentaer bedingte Einengung des Spinalkanals, die zur Kompression der Nervenwurzeln oder des Duralsacks fuehren kann. Die lumbale Spinalkanalstenose manifestiert sich klinisch als Komplex aus Rueckenschmerzen sowie sensiblen und motorischen neurologischen Ausfaellen, die in der Regel belastungsabhaengig sind (Claudicatio spinalis). Die bildgebende Diagnostik mittels Magnetresonanztomographie, Computertomographie und Myelographie spielt eine entscheidende Rolle bei der optimalen patientenbezogenen Therapieentscheidung. (orig.)

  8. Hydrodynamic Modeling to Assess the Impact of Man-Made Fishing Canals on Floodplain Dynamics: A Case Study in the Logone Floodplain

    Science.gov (United States)

    Shastry, A. R.; Durand, M. T.; Fernandez, A.; Phang, S. C.; Hamilton, I.; Laborde, S.; Mark, B. G.; Moritz, M.; Neal, J. C.

    2017-12-01

    The Logone floodplain in northern Cameroon, also known as Yaayre, is an excellent example of coupled human-natural systems because of strong couplings between social, ecological and hydrologic systems. Overbank flow from the Logone River inundates the floodplain ( 8000 km2) annually and the flood is essential for fish populations and the fishers that depend on them for their livelihood. However, a recent trend of construction of fishing canals threatens to change flood dynamics like duration and timing of onset and may reduce fish productivity. Fishers dig canals during dry season, which are used to catch fish by collecting and channeling water during the flood recession. By connecting the floodplain to the river, these fishing canals act an extension of the river drainage network. The goal of this study is to characterize the relationship between the observed exponential increase in numbers of fishing canals and flood dynamics. We modelled the Logone floodplain as a two-dimensional hydrodynamic model with sub-grid parameterizations of channels using LISFLOOD-FP. We use a simplified version of the hydraulic system at a grid-cell size of 1-km, upscaled using a new high accuracy map of global terrain elevations from Shuttle Radar Topography Mission (SRTM). Using data from a field-collected survey performed in 2014, 1120 fishing canal were collated and parameterized as 111 sub-grid channels and the fishnet structure was represented as a combination of weir and mesh screens. 49 mapped floodplain depressions were also represented as sub-grid channels. In situ discharge observations available at Katoa between 2001 and 2007 were used as input for the model. Preliminary results show that presence of canals resulted in a 24% quicker recession of water in the natural depressions showing increasing canal numbers lead to quicker flood recession. We also investigate the rate of effect increasing number of fishing canals has on flood recession by simulating varying numbers of

  9. Preparación de canales curvos y calcificados

    Directory of Open Access Journals (Sweden)

    Karen Sofia Gallego Lopez

    2013-10-01

    in curved canals and calcified due to the complexity of these, the implemented techniques, and instrumentation suitable for the preparation of pipes have been many in order to minimize errors during preparation. But any technique or instrument itself ideal in preventing these errors, it is necessary to comply with some basic principles for the preparation of these channels, such as proper preparation coronal, the continued use of irrigants and chelating agents, maintenance of the permeability, filing anticurvatura and double taper. The incorrectness of these principles leads to errors which hinder the success of endodontic treatment. The progress of science and the advent of nickel-titanium instrument, it has been facilitating both root canal treatment is no longer considered previously attributed to him was a difficult procedure, the important thing to predict the orientation and anatomy through before using or instrumental techniques, since an error in them will lead to treatment failure.Keywords: development; calcification; root canal.

  10. Effects of irrigation solutions and Calcium hydroxide dressing on root canal treatments of periapical lesions

    OpenAIRE

    Nirmala, Vita

    2006-01-01

    The preparation of root canal in endodontic treatment plays an important role in treating non vital teeth with periapical lesion. Some factors influence the success of root canal treatment in short and long terms are the irrigation of root canal using antiseptic solution and the use of root canal medicament. The aim of this literature study is to determined the effect of irrigation solution and Calcium hydroxide dressing in root canal treatment of periapical lesions. The use of root canal med...

  11. Momento de inercia a la torsión de barras de perfil canal // Torsional inertia Moment for a profile bar channel

    Directory of Open Access Journals (Sweden)

    R. Rivero Galán

    1998-01-01

    Full Text Available En el presente trabajo se brindan fórmulas y coeficientes para la determinación del momento de inercia a la torsión de una barrade perfil canal. Las fórmulas obtenidas se validan mediante la simulación de diferentes estructuras de uniones entre canales conel uso del método de los elementos finitos._______________________________________________________________________AbstractIn the paper are offered formulations and coefficients for the determination of the moment of inertia to the twist for a profilebar channel. The obtained formulations are validated through the simulation by the finite elements method of differentstructures of unions between channels.

  12. The Effects of NiTi Hand and Rotary Canal Master U and K-Flex Instrumentation of Root Canal Morphology

    Science.gov (United States)

    1992-09-01

    Rotary Canal Master "U" and K-Flex Instrumentation of Root Canal Morphology 6. AUTHOR(S) Robert H. Haller 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES... endodontic failure. B. STATET OF THE PREL]2U Conventional endodontic instruments have re.nained basically unchanged since the introduction of the K-type...F;hcw"e that this nO𔃾 instruneent destim tended ti- produce rounder pr rMticns with • t!-rnnVortaticn than c rnvrnticnal 4 endodontic instruments

  13. 33 CFR 117.181 - Oakland Inner Harbor Tidal Canal.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Oakland Inner Harbor Tidal Canal. 117.181 Section 117.181 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... Tidal Canal. The draws of the Alameda County highway drawbridges at Park Street, mile 5.2; Fruitvale...

  14. File list: InP.CDV.05.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.CDV.05.AllAg.Atrioventicular_canals mm9 Input control Cardiovascular Atrioventicular canals... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/InP.CDV.05.AllAg.Atrioventicular_canals.bed ...

  15. File list: NoD.CDV.20.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available NoD.CDV.20.AllAg.Atrioventicular_canals mm9 No description Cardiovascular Atrioventicular canals... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/NoD.CDV.20.AllAg.Atrioventicular_canals.bed ...

  16. File list: InP.CDV.20.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  17. File list: NoD.CDV.50.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  18. File list: NoD.CDV.10.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  19. File list: NoD.CDV.05.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  20. File list: InP.CDV.50.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  1. File list: InP.CDV.10.AllAg.Atrioventicular_canals [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.CDV.10.AllAg.Atrioventicular_canals mm9 Input control Cardiovascular Atrioventicular canals... http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/InP.CDV.10.AllAg.Atrioventicular_canals.bed ...

  2. Evaluation of the anterior and posterior ethmoidal canal by computed tomography

    International Nuclear Information System (INIS)

    Cankal, F.; Apaydin, N.; Acar, H.I.; Elhan, A.; Tekdemir, I.; Yurdakul, M.; Kaya, M.; Esmer, A.F.

    2004-01-01

    AIM: To examine the anatomy, length and angulation of the anterior and posterior ethmoidal canals (AECs and PECs) using computed tomography (CT), and to determine the anatomical landmarks in which the canals are expected to be seen in transverse and coronal planes. MATERIALS AND METHODS: CT images of 150 patients were analysed. One, 2, and 3 mm thick sections were obtained separately in axial and coronal images. The frequency of visualization of the AECs and PECs, and if present, a third canal, was noted. The course and the angulation of the AEC and the PEC in transverse and coronal planes were recorded. On axial sections the distance between the AEC and PEC and the previously defined landmarks were measured. On coronal images, the distances were calculated from the thickness of the cross-section and the number of sections between the various structures. RESULTS: The AEC was identified as a separate canal in 84% of patients, and was embedded in the ethmoid roof in 16%. The PEC was seen as a separate canal in 8% and was present in the ethmoid roof in 92%. On the 1 mm thick coronal and transverse sections, a third canal was identified at the junction of the middle and posterior third of the AEC-PEC distance in both of the images. The average lengths of these canals were 4-12 mm (mean 8.2 mm) for the AEC, and 2-13 mm (mean 7.6 mm) for the PEC. CONCLUSIONS: To avoid the complications that can develop during endoscopic sinus surgery; the course, length and the angulations of the anterior and posterior ethmoidal arteries and their canals can be identified by CT in standard positions if a sufficiently thin section thickness is used. The present study has shown the exact CT localization of the AECs and PECS, which are frequently overlooked when evaluating para-nasal sinuses

  3. Effectiveness of EDTA as the irrigation solution to remove smear layer in root canal

    OpenAIRE

    Kurniasri Amas Achiar; Endang Sukartini

    2009-01-01

    One of the objectives of successful endodontic treatment is the hermetic obturation of the root canal system. To achieve this, the root canal filling must seal the canal space both apically and coronally to prevent the ingress of microorganisms or tissue fluids into the canal space. Apical leakage is reported a common reason for the clinical failure of endodontic therapy. Leakage through an obturated root canal is expected to take place at interfaces between sealer and dentin or sealer and gu...

  4. Magnetic Resonance Imaging Quantification of Lumbar Spinal Canal Stenosis in Symptomatic Subjects

    Directory of Open Access Journals (Sweden)

    Siddarth Ragupathi

    2017-10-01

    Full Text Available Introduction: Low backache is a common condition to occur in the middle age. It is mainly caused by the degeneration of the intervertebral disc which forms the main support to the vertebral column. Lumbar spinal canal stenosis results in the compression of spinal cord and nerves at the level of lumbar vertebra. Aim: The purpose of this study is to measure the spinal canal dimensions and correlate with the clinical symptoms to establish a radiological criterion based on MRI for diagnosis of lumbar canal stenosis. This study is done to improve the diagnostic accuracy of lumbar spinal canal stenosis. Materials and Methods: Two hundred subjects with complaints of low backache without a traumatic history underwent Magnetic Resonance Imaging (MRI after assessment of pain by two methods: 1. Oswestry Disability Index (ODI scoring and 2. Wong Baker Facial Expression scale. All the images were qualitatively analyzed to obtain the MRI grading for central canal at various levels from L1 to S1 vertebra after making sure that the neural foramina is not involved. Anteroposterior (AP and transverse diameter of spinal canal at intervertebral disc and upper part of vertebral body levels and spinal canal area are measurements that are taken. Descriptive and inferential statistical analysis has been carried out in the present study. Results on continuous measurements are presented on mean±SD (min-max and results on categorical measurements are presented in number (%. Significance is assessed at 5% level of significance. Results: The spinal canal diameter measured along its AP and transverse direction is found to be correlating with the severity of low backache complained by the patient. Comparing the two methods of clinical assessment, ODI scoring was found to be more significant. Conclusion: The spinal canal measurements can be used as a radiologic criterion for diagnosis of acquired lumbar spinal canal stenosis. This will improve the diagnostic accuracy. However

  5. Cervical Cord-Canal Mismatch: A New Method for Identifying Predisposition to Spinal Cord Injury.

    Science.gov (United States)

    Nouri, Aria; Montejo, Julio; Sun, Xin; Virojanapa, Justin; Kolb, Luis E; Abbed, Khalid M; Cheng, Joseph S

    2017-12-01

    The risk for spinal cord injuries (SCIs) ranging from devastating traumatic injuries, compression because of degenerative pathology, and neurapraxia is increased in patients with congenital spinal stenosis. Classical diagnostic criteria include an absolute anteroposterior diameter of spinal cord, which varies across patients, independent of canal size. Recent large magnetic resonance imaging studies of population cohorts have allowed newer methods to emerge that account for both cord and canal size by measuring a spinal cord occupation ratio (SCOR). A SCOR defined as ≥70% on midsagittal imaging or ≥80% on axial imaging appears to be an effective method of identifying cord-canal mismatch, but requires further validation. Cord-canal size mismatch predisposes patients to SCI because of 1) less space within the canal lowering the amount of degenerative changes needed for cord compression, and 2) less cerebrospinal fluid surrounding the spinal cord decreasing the ability to absorb kinetic forces directed at the spine. Patients with cord-canal mismatch have been reported to be at a substantially higher risk of traumatic SCI, and present with degenerative cervical myelopathy at a younger age than patients without cord-canal mismatch. However, neurologic outcome after SCI has occurred does not appear to be different in patients with or without a cord-canal mismatch. Recognition that canal and cord size are both factors which predispose to SCI supports that cord-canal size mismatch rather than a narrow cervical canal in isolation should be viewed as the underlying mechanism predisposing to SCI. Copyright © 2017. Published by Elsevier Inc.

  6. Evaluation of the root canal shaping ability of two rotary nickel-titanium systems.

    Science.gov (United States)

    Al-Manei, K K; Al-Hadlaq, S M S

    2014-10-01

    The aim was to investigate the canal shaping abilities of the twisted file (TF) and GT series X file (GTX) systems. Sixty mesial root canals of mandibular molars with curvatures of 15-50° were divided randomly into two groups of 30 canals each. The teeth were sectioned horizontally at 3, 6 and 9 mm from the apex. Root canals were prepared with TF and GTX files, respectively, and the shaping abilities of the systems were evaluated at three levels (coronal, middle and apical) based on the comparison of pre- and post-instrumentation photographs using AutoCAD software. Preparation time was also assessed. Data from the two groups were compared statistically using the Student's t-test. There was no significant difference between the rotary systems in terms of change in root canal cross-sectional area, root canal transportation, centring ability or minimum dentine thickness. Remaining dentine thickness at the coronal and middle levels was similar in the TF and GTX groups, but GTX instruments left significantly less dentine than TF instruments on the mesial aspects of root canals at the apical level. Root canal preparation with TF instruments required significantly less time than with GTX instruments. The TF and GTX NiTi rotary instruments showed similar shaping abilities, but root canal preparation was more rapid with the TF than with the GTX system. © 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  7. Design Of The Canal System Of KLA-60 Condensation Produce

    International Nuclear Information System (INIS)

    Sriawan; Wiranto, Slamet

    2000-01-01

    The RSG-GAS reactor pool ventilation system (KLA-60) which be used to avoid circulation of contamination air in the reactor hall, flow the 60% air from the pool surface to stack through the various filters. In case the isolation building the air from the pool surface is flooded back to the operation hall after exceed the heat exchanger, cooler and the various filters. One of the weakness of this system and must be solved by RSG is handing of the condensation water because in the canal system of the KLA-60 condensation produce is to be found some soiled like algae and to go the reactor pool. To solve this problem should be carried out research about the canal system of KLA-60 condensation produce and design the new canal system to find the good function. At the first design is carried out study about the function of the old of canal system of KLA-60 condensation produce. Base on this study have been carried out design of the canal system KLA-60 condensation produce, with can prevent the soiled to go to the reactor pool

  8. Mandibular lingual vascular canals (MLVC): Evaluation on dental CTs of a case series

    Energy Technology Data Exchange (ETDEWEB)

    Scaravilli, Maria Serena; Mariniello, Mauro [Department of Oral and Maxillo-Facial Sciences, Section of Oral and Implant Surgery, University of Naples ' Federico II' , Naples (Italy); Sammartino, Gilberto, E-mail: serena.scaravilli@gmail.com [Department of Oral and Maxillo-Facial Sciences, Section of Oral and Implant Surgery, University of Naples ' Federico II' , Naples (Italy)

    2010-11-15

    Purpose: The aim of this study was to assess the anatomy of the mandibular lingual foramen (MLF) and its linked canals (mandibular lingual vascular canals - MLVC), describing their frequency, diameter, location, and course. Materials and methods: One hundred and fourteen computed tomography (CT) images of the mandible (57 male and 57 female; mean age 44.70 {+-} 12.53; age range 13-75 years, were evaluated. The CT sections were obtained on axial plane by using a bone reconstruction algorithm and then processed with dedicated software (Dentascan), with a standard protocol. Results: 103 patients (90.35%) had at least one lingual vascular canal and 52 (45.61%) had multiple (two or three) canals. The typical locations of MLVC were the midline of the mandible (median lingual canal [MLC]). The mean diameter of the lingual canals in the midline (MLC) was 0.8 mm {+-} 0. The direction of MLC progresses in an anterior and slightly caudal sense. Conclusions: Dental CT examination easily demonstrates the presence, position, direction and size of the lingual foramen and of the lingual vascular canals of the mandible. Radiologists and oral surgeons should be aware of these canals and their importance, in order to prevent bleeding complications during implants placement and other surgical procedures.

  9. Leiomyoma of the anal canal: report of two cases.

    Science.gov (United States)

    Witz, M; Bernheim, J; Griffel, B; Dinbar, A

    1986-10-01

    Leiomyoma of the rectum and anal canal is an unusual clinical entity. Generally, it does not produce any clinical signs and in most cases it is discovered incidentally in the course of routine rectal examination. The clinical presentation, diagnosis, and surgical treatment are described in two presented cases of anal canal leiomyoma.

  10. ProTaper rotary instrument fracture during root canal preparation: a comparison between rotary and hybrid techniques.

    Science.gov (United States)

    Farid, Huma; Khan, Farhan Raza; Rahman, Munawar

    2013-03-01

    This study aimed to compare the frequency of ProTaper rotary instrument fracture with rotary (conventional) and hybrid (rotary and hand files) canal preparation techniques. Secondary objectives were to determine whether there was an association of ProTaper file fracture with the canal curvature and to compare the mean time required for canal preparation in the two techniques. An in vitro experiment was conducted on 216 buccal canals of extracted maxillary and mandibular first molars. After creating an access cavity and a glide path for each canal, a periapical radiograph was taken and the canal curvature was measured with Schneider's technique. The canals were then randomly divided into Group A (rotary technique) and Group B (hybrid technique). The length of ProTaper files were measured before and after each canal preparation. Time taken for each canal preparation was recorded. A total of seven ProTaper files fractured in Group A (P=0.014) in canals with a curvature >25 degrees (PProTaper rotary files, although time consuming, was safer in canals having a curvature greater than 25 degrees.

  11. Vestibulo-Ocular Reflex Abnormalities in Posterior Semicircular Canal Benign Paroxysmal Positional Vertigo: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Tayyebe Fallahnezhad

    2017-09-01

    Full Text Available Introduction: Benign paroxysmal positional vertigo (BPPV, involving the semicircular canals, is one of the most common diseases of the inner ear. The video head impulse test (vHIT is a new test that examines the function of the canals. This study aimed to investigate the vestibulo-ocular reflex (VOR gain, gain asymmetry and saccades after stimulating all six canals in patients definitively diagnosed with posterior semicircular canal BPPV (PSC-BPPV.   Materials and Methods: Twenty-nine unilateral PSC-BPPV patients with normal oculographic and caloric results were enrolled in this study. vHIT was performed on six canals, and VOR gain, gain asymmetry and saccades were measured.   Results: Sixteen (55.17% patients had abnormal posterior canal VOR gains in the ipsilesional ear. VOR gains in both horizontal canals were within normal limits. Superior canal VOR gains were mostly lower than normal and were not correlated to PSC abnormalities (P>0.05. No corrective saccades could be observed.   Conclusion: VOR gain in the direction of the posterior semicircular canal may be reduced in PSC-BPPV patients. Evaluation of PSC-VOR parameters could be beneficial, although superior canal measurements should be interpreted with caution.

  12. The circulation of the cerebrospinal fluid (CSF) in the spinal canal

    Science.gov (United States)

    Sanchez, Antonio L.; Martinez-Bazan, Carlos; Lasheras, Juan C.

    2016-11-01

    Cerebrospinal Fluid (CSF) is secreted in the choroid plexus in the lateral sinuses of the brain and fills the subarachnoid space bathing the external surfaces of the brain and the spinal canal. Absence of CSF circulation has been shown to impede its physiological function that includes, among others, supplying nutrients to neuronal and glial cells and removing the waste products of cellular metabolism. Radionuclide scanning images published by Di Chiro in 1964 showed upward migration of particle tracers from the lumbar region of the spinal canal, thereby suggesting the presence of an active bulk circulation responsible for bringing fresh CSF into the spinal canal and returning a portion of it to the cranial vault. However, the existence of this slow moving bulk circulation in the spinal canal has been a subject of dispute for the last 50 years. To date, there has been no physical explanation for the mechanism responsible for the establishment of such a bulk motion. We present a perturbation analysis of the flow in an idealized model of the spinal canal and show how steady streaming could be responsible for the establishment of such a circulation. The results of this analysis are compared to flow measurements conducted on in-vitro models of the spinal canal of adult humans.

  13. NMR imaging of the vertebral column and the spinal canal. 2. rev. and enl. ed.

    International Nuclear Information System (INIS)

    Forsting, Michael; Uhlenbrock, Detlev; Wanke, Isabel; Universitaetsklinikum Essen

    2009-01-01

    The book on the MRT (magnetic resonance tomography) of the vertebral cord and spinal canal covers the following topics: physics fundamentals and application; malformation of the spinal canal; degenerative vertebral column diseases; vertebral column and spinal canal carcinomas; inflammatory diseases of the vertebral column and the spinal canal; applicability of MRT in case of acute spinal cord traumata; vascular diseases of the spinal canal

  14. Modeling and simulation of driver's anticipation effect in a two lane system on curved road with slope

    Science.gov (United States)

    Kaur, Ramanpreet; Sharma, Sapna

    2018-06-01

    The complexity of traffic flow phenomena on curved road with slope is investigated and a new lattice model is presented with the addition of driver's anticipation effect for two lane system. The condition under which the free flow turns into the jammed one, is obtained theoretically by using stability analysis. The results obtained through linear analysis indicates that the stable region increases (decreases) corresponding to uphill (downhill) case due to increasing slope angle for fixed anticipation parameter. It is found that when the vehicular density becomes higher than a critical value, traffic jam appears in the form of kink antikink density waves. Analytically, the kink antikink density waves are described by the solution of mKdV equation obtained from non linear analysis. In addition, the theoretical results has been verified through numerical simulation, which confirm that the slope on a curved highway significantly influence the traffic dynamics and traffic jam can be suppressed efficiently by considering the anticipation parameter in a two lane lattice model when lane changing is allowed.

  15. Classification of ASKAP Vast Radio Light Curves

    Science.gov (United States)

    Rebbapragada, Umaa; Lo, Kitty; Wagstaff, Kiri L.; Reed, Colorado; Murphy, Tara; Thompson, David R.

    2012-01-01

    The VAST survey is a wide-field survey that observes with unprecedented instrument sensitivity (0.5 mJy or lower) and repeat cadence (a goal of 5 seconds) that will enable novel scientific discoveries related to known and unknown classes of radio transients and variables. Given the unprecedented observing characteristics of VAST, it is important to estimate source classification performance, and determine best practices prior to the launch of ASKAP's BETA in 2012. The goal of this study is to identify light curve characterization and classification algorithms that are best suited for archival VAST light curve classification. We perform our experiments on light curve simulations of eight source types and achieve best case performance of approximately 90% accuracy. We note that classification performance is most influenced by light curve characterization rather than classifier algorithm.

  16. Bank erosion of navigation canals in the western and central Gulf of Mexico

    Science.gov (United States)

    Thatcher, Cindy A.; Hartley, Stephen B.; Wilson, Scott A.

    2011-01-01

    Erosion of navigation canal banks is a direct cause of land loss, but there has been little quantitative analysis to determine why certain major canals exhibit faster widening rates (indicative of erosion) than others in the coastal zones of Texas, Louisiana, Mississippi, and Alabama. We hypothesize that navigation canals exhibit varying rates of erosion based on soil properties of the embankment substrate, vegetation type, geologic region (derived from digital versions of state geologic maps), and the presence or absence of canal bank armaments (that is, rock rip-rap, concrete bulkheads, or other shoreline protection structures). The first objective of this project was to map the shoreline position and substrate along both banks of the navigation canals, which were digitized from 3 different time periods of aerial photography spanning the years of 1978/79 to 2005/06. The second objective was to quantify the erosion rates of the navigation canals in the study area and to determine whether differences in erosion rates are related to embankment substrate, vegetation type, geologic region, or soil type. To measure changes in shoreline position over time, transects spaced at 50-m (164-ft) intervals were intersected with shorelines from all three time periods, and an annual rate of change was calculated for each transect. Mean annual rates of shoreline change ranged from 1.75 m/year (5.74 ft/year) on the west side of the Atchafalaya River, La., where there was shoreline advancement or canal narrowing, to -3.29 m/year (-10.79 ft/year) on the south side of the Theodore Ship Channel, Ala., where there was shoreline retreat or erosion. Statistical analysis indicated that there were significant differences in shoreline retreat rates according to geologic region and marsh vegetation type, and a weak relationship with soil organic content. This information can be used to better estimate future land loss rates associated with navigation canals and to prioritize the location of

  17. MRI diagnosis of embryonal tumors in the spinal canal

    International Nuclear Information System (INIS)

    Sun Jilin; Zhang Xinchuan; Zhang Huaning; Liu Lianxiang; Wu Yujin

    1997-01-01

    To evaluate MRI diagnostic value of the embryonal tumors in the spinal canal. Materials and methods: The MRI appearances of 15 cases of histologically confirmed embryonal tumors in the spinal canal were analyzed. (1) Lipoma (3 cases) had characteristic MRI appearance, demonstrating high signal intensity on T 1 WI, and moderately high signal on T 2 WI. High signal intensity of the lipoma was turned into low signal intensity by fat suppression technique. (2) Dermoids (2 cases) and epidermoid (7 cases) exhibiting low or iso-low signal on T 1 WI and high or iso-high signal on T 2 WI. All had an iso-intense capsule on T 1 WI. However, the two tumors could not be distinguished from each other. (3) Teratoma (3 cases) appeared as a mass of inhomo-generous signals in the spinal canal including soft tissue, fatty tissue and calcification within the same tumor. The diagnosis of embryonal tumors in the spinal canal mainly depend on their MRI appearances, specific tumor location and patient's age

  18. Nutrient canals on mandibular anterior region in cone beam computed tomography

    International Nuclear Information System (INIS)

    Kang, Jung Ho; Kim, Gyu Tae; Choi, Yong Suk; Hwang, Eui Hwan

    2006-01-01

    To evaluate location, distribution, diameter, and length of the nutrient canals on mandibular anterior region using a cone beam computed tomography (CBCT). Mandibular CBCT was performed on 33 adults (18 males and 15 female) with no history of systemic disease, and any other dental surgery history. Location, distribution, diameter, and length of the nutrient canals on mandibular anterior region were radiographically evaluated. A statistical comparison was done by SPSS. In the location and distribution of nutrient canals, they were found in 6.8% at labial portion above root apex, in 93.28% at lingual portion above root apex in 46.2% at labial portion below root apex, and in 53.6% at lingual portion below root apex. Nutrient canals at lingual portion above root apex were most frequently observed between central and lateral incisors, and those at labial and lingual portion below root apex were most frequently observed between central incisors. The mean diameters of nutrient canals were 0.54 mm at labial portion above root apex, 0.61 mm at lingual portion above root apex, 0.66 mm at labial portion below root apex, and 0.76 mm at lingual portion below root apex. The mean lengths of nutrient canals were 2.63 mm at labial portion above root apex, 3.74 mm at lingual portion above root apex, 4.51 mm at labial portion below root apex, and 6.77 mm at lingual portion below root apex. CBCT is useful device to evaluate the anatomical structure of nutrient canals on mandibular anterior region

  19. Nutrient canals on mandibular anterior region in cone beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Jung Ho; Kim, Gyu Tae; Choi, Yong Suk; Hwang, Eui Hwan [Kyung Hee Univ. College of Dentistry, Seoul (Korea, Republic of)

    2006-09-15

    To evaluate location, distribution, diameter, and length of the nutrient canals on mandibular anterior region using a cone beam computed tomography (CBCT). Mandibular CBCT was performed on 33 adults (18 males and 15 female) with no history of systemic disease, and any other dental surgery history. Location, distribution, diameter, and length of the nutrient canals on mandibular anterior region were radiographically evaluated. A statistical comparison was done by SPSS. In the location and distribution of nutrient canals, they were found in 6.8% at labial portion above root apex, in 93.28% at lingual portion above root apex in 46.2% at labial portion below root apex, and in 53.6% at lingual portion below root apex. Nutrient canals at lingual portion above root apex were most frequently observed between central and lateral incisors, and those at labial and lingual portion below root apex were most frequently observed between central incisors. The mean diameters of nutrient canals were 0.54 mm at labial portion above root apex, 0.61 mm at lingual portion above root apex, 0.66 mm at labial portion below root apex, and 0.76 mm at lingual portion below root apex. The mean lengths of nutrient canals were 2.63 mm at labial portion above root apex, 3.74 mm at lingual portion above root apex, 4.51 mm at labial portion below root apex, and 6.77 mm at lingual portion below root apex. CBCT is useful device to evaluate the anatomical structure of nutrient canals on mandibular anterior region.

  20. Canal rays

    International Nuclear Information System (INIS)

    Goldstein, Eugen

    2010-01-01

    For more than fifty years the German physicist Eugen Goldstein was engaged in an obscure fringe field of physics, on which he has impressed like no other: Electrical gas discharges. Goldstein describes in this book his discovery of canal rays, which has given important impulses for modern atomic physics. For his research Goldstein received the Prix Hebert of the Parisienne Academie des sciences, the Hughes medal, and was repeatedly proposed for the Nobel prize. In Germany for the Jewish scientist the acknowledgement remained far-reachingly refused until after the war.