Performance Evaluation of Copper and Stainless-steel Electrodes in Electrical Tomographic Imaging

Geophysicists use electrical methods to investigate and characterise the earth’s subsurface geology. This study aims to evaluate the performance of copper and conventional stainless-steel electrodes in subsurface tomographic investigations using electrical resistivity tomography (ERT) and induced polarisation (IP) at two sites in Penang, Malaysia. Site 1 and Site 2 employed profile lengths of 200 m and 100 m, with electrodes spacing of 5.0 m and 2.5 m, respectively. In the results of the final data inversion, it was observed that the ERT and IP tomographic models of Site 1 have the best convergence limits with percentage relative differences (copper as reference model) ranging from –70% to 70%, while Site 2 recorded –8% to 8%. The electrodes performance evaluation showed that population root mean square (RMS) error and population mean absolute percentage error (MAPE) of data points between copper and stainless-steel electrodes yielded large values for Site 1 with values above 28% and that of Site 2 was less than 4%. Hence, copper (good electrical conductivity and non-polarisable) electrodes have improved the quality and quantity of infield data which give low values of population RMS error and population MAPE compared to conventional stainless-steel electrodes, especially for large unit electrode spacing surveys. Most notably, this work has contributed to the understanding of the capability of copper electrodes in providing precise and reliable inversion models for subsurface tomographic investigations in pre- and post-land uses (engineering work), hydrogeology/groundwater, environmental studies, etc.

CROWN DOWN PREPARATION TECHNIQUE WITH LARGE TAPER ENDODONTIC HAND INSTRUMENT

Introduction: Root canal preparation is an important step in root canal treatment. The use of stainless steel K-Files is time-consuming and causes fatigue to patients and operators. The large taper endodontic hand instrument can be used as an option for another preparation instrument. The purpose of this article is to determine the advantages of using large taper endodontic hand instruments as a preparation instrument compared to conventional stainless steel K-Files. Case: The 24-year-old male patient presented with pain in his lower left tooth even though it was not used. Examination of teeth 35, percussion and press (+), palpation (-), CE (-), exploration of root canals with smooth broach (+). There was a radiolucent image in the distal crown that had reached the pulp chamber, radiolucency with a blurred border of 2 mm in diameter at the periapical area, and the dilation of the periodontal ligaments along with the roots. Tooth 35 diagnosis was partial pulp necrosis with periapical lesions. Case Management: Root canal treatment of teeth 35 using hand-used ProTaper with the crown down technique up to F4 WL = 21 mm. Obturation with single cone technique with Endomethasone as a sealer. Discussion: The large taper instrument is very flexible and easily enters narrow and bent root canals, thus it can shorten the working time, reduce the risk of fatigue for patients and operators, improves the cleaning of the root canal system, and consistent root canal formation. The crown down technique used can reduce the risk of preparation errors, prevent debris extrusion and improve obturation quality. Conclusion: Root canal preparation using a large taper endodontic hand instrument can shorten the working time and reduce the risk of fatigue for patients and operators compared to preparations using conventional stainless steel K-File.

Abstaining from symptomatic implants of modified tension band wiring by nonabsorbable suture fixation for transverse patella fractures

Background Modified tension band fixation has become commonly used for transverse patella fractures. The conventional stainless steel wire provides sufficient stability but may be associated with complications. Objective The study aimed to evaluate the effectiveness of a new modified tension band fixation technique for transverse patella fractures using a nonabsorbable suture. Material and methods We present the result of a prospective series using a nonabsorbable suture (FiberWire) for transverse patella fractures. The mean follow-up period totaled 12 months. A total of 16 patients were evaluated by radiographic and clinical review. The postoperative clinical evaluation employed Lysholm and Böstman scores. Result All clinical results on follow-up were good to excellent. Minimal intra-articular joint stepping and further fracture displacement were recorded. No patient needed re-operation, and functional outcomes of the knee were satisfactory. No significant differences were found between the injured and contralateral knee range of motion. No symptomatic implants and skin complications were noted, and all fractures were completed heal within 15 weeks. Conclusion FiberWire provided sufficient stability and reduced postoperative complications. The results proved appropriate, and the technique has merit, as it obviates the need for re-operation.

Measure and compare the Degree of Root Canal Transportation and Canal-centering ability of Twisted, ProTaper, and Conventional Stainless Steel K Files using Spiral Computed Tomography: An in vitro Study

ABSTRACT Aim The aim of this study was to compare canal transportation and centering ability of Twisted files (TF) and ProTaper (PT) files with conventional stainless steel (SS) K files. Materials and methods Thirty mandibular premolar teeth with root curvature of 25 to 35° were selected. The samples were randomly divided into three groups of 10 each according to the type of files used for instrumentation. Group I was instrumented using TF, group II with PT files according to the manufacturer's recommendations, and group III with samples prepared with precurved SS K files using a step-back technique. After preparation, the samples were assessed using spiral computed tomography. Three sections were recorded at coronal, middle, and apical levels. Amount of transportation was assessed comparing with preinstrumentation images. Centering ability was calculated using Gambill's formula. The three groups were statistically compared using Student's t-test. Results Twisted files showed the least canal transportation and the best centering ability followed by PT file system. Stainless steel K files showed the highest transportation and least centering ability. Conclusion Twisted files showed the least amount of transportation and better centering compared with the other file systems. Clinical significance The study gives information of TF, a recently introduced rotary system (2008) with regard to its efficacy in preparing curved root canals. This study has shown that the centering ratio of rotary nickel titanium was better than that of SS files. How to cite this article Rejula F, Christalin R, Ahmed W, Dinakaran S, Gopinathan AS, Babu A. Measure and compare the Degree of Root Canal Transportation and Canalcentering ability of Twisted, ProTaper, and Conventional Stainless Steel K Files using Spiral Computed Tomography: An in vitro Study. J Contemp Dent Pract 2017;18(6):463-469.

An in vitro Evaluation of Friction Characteristics of Conventional Stainless Steel and Self-ligating Stainless Steel Brackets with different Dimensions of Archwires in Various Bracket–archwire Combination

ABSTRACT Aim The purpose of this research is to compare the frictional attributes of stainless steel conventional brackets and selfligating stainless steel brackets with different dimensions of archwires. Materials and methods The test was carried with two sets of maxillary brackets: (1) Conventional stainless steel (Victory Series), (2) stainless steel self-ligating (SmartClip) without first premolar brackets. Stainless steel, nickel–titanium (NiTi), and beta-Ti which are the types of orthodontic wire alloys were tested in this study. To monitor the frictional force, a universal testing machine (Instron 33R 4467) that comprises 10 kg tension load cell was assigned on a range of 1 kg and determined from 0 to 2 kg, which allows moving of an archwire along the brackets. One-way analysis of variance was used to test the difference between groups. To analyze the statistical difference between the two groups, Student's t-test was used. Results For Victory Series in static friction, p-value was 0.946 and for kinetic friction it was 0.944; at the same time for SmartClip, the p value for static and kinetic frictional resistance was 0.497 and 0.518 respectively. Hence, there was no statistically significant difference between the NiTi and stainless steel archwires. Conclusion It is concluded that when compared with conventional brackets with stainless steel ligatures, self-ligating brackets can produce significantly less friction during sliding. Beta-Ti archwires expressed high amount of frictional resistance and the stainless steel archwires comprise low frictional resistance among all the archwire materials. Clinical significance In orthodontics, frictional resistance has always had a major role. Its ability to impair tooth movement leads to the need for higher forces to move the teeth and it extends the treatment time which results in loss of posterior anchorage. Friction in orthodontics is related with sliding mechanics when a wire is moving through one or a series of bracket slots. How to cite this article Sridharan K, Sandbhor S, Rajasekaran UB, Sam G, Ramees MM, Abraham EA. An in vitro Evaluation of Friction Characteristics of Conventional Stainless Steel and Selfligating Stainless Steel Brackets with different Dimensions of Archwires in Various Bracket–archwire Combination. J Contemp Dent Pract 2017;18(8):660-664.

Safe use of subdermal needles for intraoperative monitoring with MRI

OBJECTIVE The purpose of this study was to develop safe, site-specific procedures for placing and leaving subdermal needle leads for intraoperative monitoring (IOM) during intraoperative MRI procedures. METHODS The authors tested a variety of standard subdermal needle electrodes designed and FDA-approved for IOM in the conventional operating room. Testing was used to determine the conditions necessary to avoid thermal injury and significant image artifacts with minimal disruption of IOM and MRI procedures. Phantom testing was performed with a fiber optic (lead) temperature monitoring system and was followed by testing of leads placed in a healthy volunteer. The volunteer testing used electrode placements typical of standard IOM cases, together with radiofrequency (RF) coil placement and imaging sequences routinely employed for these case types. Lead length was investigated to assess heating effects for electrodes placed within the RF coil. RESULTS The authors found that conventional stainless steel (SS) and platinum/iridium (Pt/Ir) subdermal needles can be used safely without significant heating when placed outside the RF coil, and this accounts for the majority or entirety of electrode placements. When placed within the RF coil, Pt/Ir leads produced minimal image artifacts, while SS leads produced potentially significant artifacts. In phantom testing, significant heating was demonstrated in both SS and Pt/Ir leads placed within the RF coil, but only during high-resolution T2-weighted scanning. This problem was largely, but not completely, eliminated when leads were shortened to 25 cm. Human testing was unremarkable except for nonpainful heating detected in a few electrodes during thin-slice (1.5 mm) FLAIR scanning. Transient irritation (skin reddening along the needle tract) was noted at 2 of the electrodes with detectable heating. CONCLUSIONS The authors were satisfied with the safety of their site-specific procedures and have begun with off-label use (following institutional review board approval and obtaining patient informed consent) of tested monitoring leads in cases that combine IOM and MRI. The authors recommend that all facilities perform their own site-specific testing of monitoring leads before proceeding with their routine use.

Electroanalytical devices with pins and thread

This work describes the adaptive use of conventional stainless steel pins—used in unmodified form or coated with carbon paste—as working, counter and quasi-reference electrodes in electrochemical devices fabricated using cotton thread or embossed omniphobic RF paper to contain the electrolyte and sample.