• Restorative Dentistry and Endodontics
• /
• v.38 no.2
• /
• pp.93-97
• /
• 2013

During root canal preparation procedures, the potential for instrument breakage is always present. When instrument breakage occurs, it leads to anxiety of the clinician and as well as a metallic obstruction of the canal which hinders further cleaning and shaping. Separated instruments must always be attempted for retrieval and if retrieval is not possible bypass should be tried. With the increased use of nickel-titanium (NiTi) instruments the incidence of separated instruments has increased. A considerable amount of research has been done to understand the various factors related to the fracture of NiTi instruments to minimize its occurrence. This paper presents a review of the literature regarding the fracture of NiTi instruments and also describes a case report showing the use of a modified 18-guage needle and cyanoacrylate glue to retrieve a separated NiTi instrument from the mesiolingual canal of a mandibular first molar.

• Restorative Dentistry and Endodontics
• /
• v.45 no.2
• /
• pp.14.1-14.7
• /
• 2020

Objective: The aim of this study was to perform a comparative evaluation of the effectiveness of ultrasonic tips versus the Terauchi file retrieval kit (TFRK) for the removal of broken endodontic instruments. Materials and Methods: A total of 80 extracted human first mandibular molars with moderate root canal curvature were selected. Following access cavity preparation canal patency was established with a size 10/15 K-file in the mesiobuccal canals of all teeth. The teeth were divided into 2 groups of 40 teeth each: the P group (ProUltra tips) and the T group (TFRK). Each group was further subdivided into 2 smaller groups of 20 teeth each according to whether ProTaper F1 rotary instruments were fractured in either the coronal third (C constituting the PC and TC groups) or the middle third (M constituting the PM and TM groups). Instrument retrieval was performed using either ProUltra tips or the TFRK. Results: The overall success rate at removing the separated instrument was 90% in group P and 95% in group T (p > 0.05) The mean time for instrument removal was higher with the ultrasonic tips than with the TFRK (p > 0.05). Conclusion: Both systems are acceptable clinical tools for instrument retrieval but the loop device in the TFRK requires slightly more dexterity than is needed for the ProUltra tips.

• Restorative Dentistry and Endodontics
• /
• v.31 no.3
• /
• pp.161-168
• /
• 2006

During root canal preparation procedures, the potential for instrument separation is always present. Files, a lentulo, a Gates-Glidden (GG) bur or any manufactured obstruction can be left behind in the canal Nickel-titanium (NiTi) rotary files are in common usage in these days. Despite their undeniable advantages, there is a potential risk of separation within the canals. It is very rapid, unpredictable, and creates a great deal of stress for the practitioner. When an endodontic instrument separates, the best option is to remove it. Ultrasonic instruments and microscopes have improved the success rate for removing separated instruments. But It is difficult and not always possible. Therefore prevention is the key. In this case report, several management methods of separated file in the canal are presented.

• Journal of Korean society of Dental Hygiene
• /
• v.9 no.3
• /
• pp.468-478
• /
• 2009

This research was performed to provide basic data for the development of infection related dental hygiene studies by surveying the current condition of recognition among students in the department of dental hygiene toward hospital infection management while receiving the following results by using a personal self-administered survey method targeting 303 students in the department of dental hygiene from certain areas. 1. With the current condition of recognition on the sanitization and sterilization of instruments among students in the department of dental hygiene(study), the rate at which surgical instruments are to be sterilized with autoclaves was 79.9% which was relatively higher than other instruments while it was shown that prosthetic instruments for treatment was 56.4%, conservative instruments for treatment was 51.8%, and ultrasonic scaler tip was 51.1% while the way syringe tips(36.1%) and the dental anesthetic apparatus(27.9%) were revealed to require sanitization by alcohol. 2. The 'hand wash' area was the highest with 4.71 while the 'materials and environment management' area and 'equipment management' area appeared high respectively with 4.43 and 4.41. 3. With the current condition of recognition on equipment management, 'equipments used for contagious patients are separately washed after a one-time use and must be sterilized or separated-and-discarded' was the highest with 4.82 while 'sterilization equipments with humidity or water on it are considered contaminated and are not used' showed the lowest recognition level with 3.90. 4. Regarding the current condition of materials and environment management, 'contagious and general trash are separated and discarded' was the highest with 4.70 while 'the refrigerator for medicine storage is cleaned on a regular basis once a month' was revealed as the lowest with 4.11. 5. With the current condition of recognition on hand washing, 'one must wash their hands after coming in contact with contagious patients, was the highest with 4.90 while washing hands after taking off gloves' appeared as the lowest with 4.51 point. To conclude department of dental hygiene there is to infection management and necessary about organization disinfecting and pasteurization to strengthen an education in order raising a stamp helping practical ratio about the infection management which whole, is from presence at a sickbed and connection does and about the infection management which is substantial and educational program development leads feed with the fact that deepening studying which is continuous must become accomplished becomes.

• Restorative Dentistry and Endodontics
• /
• v.46 no.4
• /
• pp.49.1-49.8
• /
• 2021

Objectives: To evaluate the fracture incidence of Reciproc R25 instruments (VDW) used during non-surgical root canal retreatments performed by students in a postgraduate endodontic program. Materials and Methods: From the analysis of clinical record cards and periapical radiographs of root canal retreatments performed by postgraduate students using the Reciproc R25, a total of 1,016 teeth (2,544 root canals) were selected. The instruments were discarded after a single use. The general incidence of instrument fractures and its frequency was analyzed considering the group of teeth and the root thirds where the fractures occurred. Statistical analysis was performed using the χ² test (p < 0.01). Results: Seven instruments were separated during the procedures. The percentage of fracture in relation to the number of instrumented canals was 0.27% and 0.68% in relation to the number of instrumented teeth. Four fractures occurred in maxillary molars, 1 in a mandibular molar, 1 in a mandibular premolar and 1 in a maxillary incisor. A greater number of fractures was observed in molars when compared with the number of fractures observed in the other dental groups (p < 0.01). Considering all of the instrument fractures, 71.43% were located in the apical third and 28.57% in the middle third (p < 0.01). One instrument fragment was removed, one bypassed, while in 5 cases, the instrument fragment remained inside the root canal. Conclusions: The use of Reciproc R25 instruments in root canal retreatments carried out by postgraduate students was associated with a low incidence of fractures.

• Progress in Superconductivity
• /
• v.14 no.2
• /
• pp.77-81
• /
• 2012

With conventional mass spectrometry (MS), ions are separated according to mass/charge (m/z) ratios. We must speculate the z values to obtain the m values. Superconducting tunnel junction (STJ) detectors can solve this problem, and true mass spectrometry becomes possible instead of m/z spectrometry. The STJ detectors were installed in MS instruments with a variety of ion sources. As an example, we report fragmentation analysis of a non-covalent protein complex of hemoglobin.

• Journal of Broadcast Engineering
• /
• v.23 no.6
• /
• pp.925-930
• /
• 2018

In this paper, we present a low profile dual-microstripline-fed double 4-arrayed meander monopole antenna with a cross-type element back by separated four-segments mesh-type reflector. The cross-type element and separated four-segments mesh-type reflector leads to enhance radiation patterns and antenna gain characteristics. The measurement value of the proposed antenna show that it has dipole-like radiation pattern characteristics. The experimental peak gain of fabricated antenna is about 2.89 dBi, which presents relatively high gain characteristics for a low profile(small-size) one. This antenna can be applied mobile RFID(radio frequency identification) readers, small medical instruments, broadcasting and home-networking operations, and other low profile high-gain systems.

• Korean Journal of Remote Sensing
• /
• v.21 no.1
• /
• pp.15-29
• /
• 2005

Superconducting Gravimeters (SG) are the most sensitive instruments for measuring temporal gravity variations. The gravimeter is an integrating sensor therefore the gravity variations caused by different sources must be separated for studying a special effect by applying different models and data analysis methods. The present reduction methods for gravity variations induced by atmosphere and hydrosphere including the ocean and the detection and determination of the most surface gravity effects are shown. Some examples demonstrate the combination of ground (SG) and space techniques especially the combination of SG with GRACE satellite derived temporal gravity variations. Resulting from the performance of the SG and the applied data analysis methods some proposals are made for future SG applications.

• Journal of Distribution Science
• /
• v.10 no.11
• /
• pp.89-99
• /
• 2012

Purpose - Mobile devices, especially mobile terminals capable of telecommunication and wireless connectivity, are leading the advancements in consumer electronics. Digital convergence drives the functions of various devices, such as cellular phones, MP3 players, personal digital assistants, and gaming, into a single device. This trend would continue and applications such as digital audio and video streaming (including personalized content delivery mechanisms) would soon be on a handheld device. As customers want mobile convergence devices, manufacturers are driving new initiatives in the emerging mobile device market. Given the roles played by device design and service content in user satisfaction of a mobile convergence device, this study focuses on identifying and measuring the constructs for the process by which user satisfaction is achieved. This study synthesizes the expectation-disconfirmation paradigm with empirical theories in user satisfaction. Device and service levels are separated, and nine key constructs for user satisfaction of mobile convergence devices are proposed. Insight into this process could help web-based businesses to improve user satisfaction, thus enhancing the effectiveness of e-commerce for sellers and buyers. Research design, data, methodology - This study draws on three users of mobile convergence devices as examples. To test there search model and hypotheses, survey questionnaires were sent to 607 mobile device users. Mobile device users were initially identified from several members, and subjects were randomly drawn. Data from 577 survey responses were finally analyzed. The unit of measurement and analysis in this research study is at a personal level. Results - The measurements for the constructs were developed and tested in a two-phase study. In the first phase, the device and service dimensions were identified, and instruments for measuring them were developed and tested. In the second phase, using the salient dimensions of the device and service as the formulating first-order factors, instruments were developed and empirically tested to measure satisfaction of the device and service. In measuring satisfaction of mobile convergence devices, the critical tasks are to identify the key constructs of such user satisfaction and to develop validated instruments to measure them. Hence, the results of this study have immediate implications for businesses and for research in user satisfaction of mobile convergence devices. Conclusions - This study provides reliable instruments for operationalizing key constructs in the analysis of user satisfaction of mobile convergence devices within the expectation-disconfirmation paradigm. Hence, convergence device makers will be able to examine whether their websites meet their customers' expectations by examining the device aspect of the mobile convergence device customers, and the service aspect expectations and disconfirmation. Moreover, the introduction of expectation and disconfirmation constructs brings the marketing aspect of convergence devices into focus for such retailers, an aspect crucial to the effective design of websites for online businesses. In addition,this study provides the metrics required to initiate future studies on user satisfaction of mobile convergence devices.

• Journal of the Korean Society of Tobacco Science
• /
• v.27 no.1 s.53
• /
• pp.134-140
• /
• 2005

The purpose of this study was the discrimination of different tobacco types by the E-Nose/tongue and the analysis of what human sensory attributes are correlated with e-instrument's sensors. Samples were made from five groups of Korean domestic tobacco leaves, aged burley and not aged, aged flue-cured and not aged and blending types of the four. Instrumental tests were conducted to discriminate characteristics among different tobacco samples by the E-Nose and the E-Tongue. Sensory attributes of tobacco tastes were impact, irritation, bitterness, hay-like, tobacco taste, smoke volume, smoke pungent and mouth cleanness. STATISTICA software was used to analyze correlation between the human sensory data and the raw data of e-instruments. Discrimination analysis can be achieved using principal components analysis (PCA) and discriminant factorial analysis(DFA). As a result, impact, bitterness, irritation, smoke volume and smoke pungent of human sensory attributes were correlated with data from the several clustered E-Nose sensors(p < 0.10). And bitterness, irritation, and smoke pungent of human sensory attributes were correlated with data from the E-Tongue sensors(p < 0.10). PCA plot by the E-Nose shows that aged tobacco and not aged were discriminated and DFA plot shows that three groups(aged burley, not aged burley and flue-cured) were discriminated. PCA plot by the E- Tongue shows that flue-cured tobacco was separated from burley. Our results indicated that the e-instruments are sensitive enough to distinguish among tobacco types and their several sensors are reacted to the human sensory attributes.