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At least 127 records · Page 7Linked to original sources

PubMed2001

The use of computed tomography when comparing nickel-titanium and stainless steel files during preparation of simulated curved canals.

AIM: The aim of this study was to compare canal preparations completed with Hedstrom and K-files of ISO size 15 - 40, made of nickel-titanium (Ni-Ti) and stainless steel (SS). METHODOLOGY: Eighty simulated canals with 200 and 30 degrees C curvatures were prepared using the step-back technique and quarter turn/pull instrument manipulation. Middle and apical level canal sections were taken using computed tomography. RESULTS: No significant difference was found between any of the file types at either level with respect to canal curvature (20 degrees or 30 degrees). At the middle level, the stainless steel files caused more enlargement toward the inner part, compared to nickel-titanium files. At the apical level, nickel-titanium canal files caused more enlargement toward the inner part, whereas more outward enlargement was caused by stainless steel instruments. No significant difference could be observed at the middle level (P > 0.05) related to the enlargement toward the outer side of the canal curvature. Transportation at both levels was significantly less (P < 0.001) for the Ni-Ti files than the SS ones. Centring ratios of the file types at the middle level were low, but not significantly different (P > 0.05), whereas at the apical level the centring ratios were significantly higher for the Ni-Ti files (P < 0.001). CONCLUSIONS: Ni-Ti instruments produced preparations with adequate enlargement, less transportation, and a better centring ratio.

Dental Instruments↗

PubMed2003

Light and scanning electron microscopic evaluation of Glyde File Prep in smear layer removal.

AIM: To evaluate the effectiveness of Glyde File Prep used in conjunction with sodium hypochlorite irrigation in the removal of smear layer produced during root canal instrumentation. METHODOLOGY: Thirty-nine extracted human teeth with single root canals were used. Access cavities were prepared and the teeth divided into three groups of 13 teeth each. Each group was treated by one of the three different regimes of irrigation and conditioning during root canal instrumentation. Group A: 0.5 mL of 1% NaOCl irrigation after each file size with an additional final irrigation of 10 mL 1% NaOCl; group B: 0.5 mL of 1% NaOCl irrigation after each file size with an additional final irrigation of 10 mL 17% EDTA; group C: Glyde File Prep coated on each instrumentation file used in conjunction with 0.5 mL 1% NaOCl irrigation after each file size and an additional final irrigation of 10 mL 1% NaOCl. The teeth were then longitudinally grooved and sectioned. Root canal cleanliness was evaluated with the aid of a Nikon light microscope (x40 and x100) and scanning electron microscope (x1000 and x3000). The debris scores obtained at three canal regions were compared statistically within the same group and among different groups using repeated measurements of analysis of variance (anova) with Bonferroni adjustments and anova with posthoc Tukey HSD, respectively. RESULTS: The canals treated with EDTA and Glyde File Prep were significantly cleaner than those treated with NaOCl alone. The apical region of the root canals generally displayed more residual smear layer, but the difference was not significant. CONCLUSIONS: Used in conjunction with NaOCl irrigation, Glyde File Prep was effective in removing smear layer produced during root canal instrumentation.

Analysis of Variance↗

PubMed1993

The effect of using files with altered tips in a sonic handpiece: an in vitro study.

The objective of this study was to establish the effect of altering the non-cutting tips on Shaper files during canal preparation with the MM1500 Sonic Air handpiece. A total of 90 simulated canals in clear resin blocks of various angles and positions of curvature were prepared using Shaper files activated by an MM1500 Sonic Air handpiece. Thirty canals were prepared with unmodified files having non-cutting tips, 30 canals were prepared with files which had their tips removed completely and a further 30 canals were prepared with files which had tips reduced by half. All canals were prepared using an identical preparation procedure which involved a linear filing motion and an anticurvature technique in curved canals. The parameters investigated included loss of canal length, weight loss from the blocks, smoothness of canal walls, transportation and overall shape of the prepared canals. The effect of altering the file tips was to increase significantly the loss of working distance and the prevalence of canal aberrations such as zips and danger zones. Altering the tips also had a detrimental effect on the pattern and extent of transportation as well as widening canals excessively in their apical third. Overall, under the conditions of this study, alterations to the non-cutting tips of Shaper files was counterproductive and resulted in canals displaying many adverse features. Conversely, retention of the non-cutting tips allowed canal preparation to proceed rapidly and effectively producing canal shapes which displayed many desirable features.

Chi-Square Distribution↗

PubMed1990

A systematic approach to preventing intracanal breakage of endodontic files.

This study was conducted to determine the effectiveness of a method to prevent intracanal breakage of endodontic files. An application schedule with a predetermined number of periods of use for K-files of all sizes was implemented at the author's clinic for a 3-year period. All the files used under this schedule were discarded after the predetermined periods of use, whether they displayed any deformity or not. During the 3-year period, 1933 files (53.7 per month) were discarded after preparation of 3269 root canals. There were 5 file fractures (0.1 per month) compared with 1.4 fractures per month before the adaptation of this system. The monthly average of files discarded during the 3-year research period was 53.7. Before the adoption of the trial system, the monthly average of discarded files was 76.5. It is concluded that the experimental system effectively reduced the incidence of intracanal instrument fractures and the total number of files consumed.

Dental Instruments↗

PubMed1995

Effectiveness of nickel-titanium files for preparing curved root canals.

In this study, the effect of 2 different endodontic files on the final shape of curved root canals of extracted single rooted teeth were examined in the scanning electron microscope. The instruments tested were a newly designed nickel-titanium endodontic file and a conventional K-type file. The files were used with in and out linear movements with a circumferential motion starting with a size 15 file. Final preparation of the apical thirds of the canals was performed with a size 35 file. Shaping effectiveness of the tested instruments was evaluated in terms of respect for conservation of the apical constriction and the presence or absence of ledging. Our observations revealed that more centered and tapered preparations were obtained with the use of the nickel-titanium files than with the conventional K-type files.

Dental Pulp Cavity↗

PubMed1999

Changes in root canal morphology in simulated curved canals over-instrumented with a variety of stainless steel and nickel titanium files.

The purpose of this project was to observe the amount of apical and mid-curve transportation produced by a range of nickel titanium (NiTi), titanium alloy and stainless steel (SS) files. Tests were carried out in simulated curved root canals produced in epoxy resin blocks. Seven commercially available file types were tested using sizes 15 to 40. Instrumentation was carried out to 1 mm beyond the apex. Changes in canal dimensions were measured at 10x magnification under a shadowgraph. There were substantial differences in the amount and the pattern of apical and mid-curve transportation produced. The amount of transportation increased with each subsequent size of file. Under the same conditions, nickel titanium files produced significantly less transportation than stainless steel files. The least apical transportation was obtained with the NiTi Mity Turbo and the most by the SS K file and SS Hedstrom file. The least mid-curve transportation was produced by the NiTi Mity Turbo and the most by the SS Hedstrom file.

Alloys↗

PubMed2004

Evaluation of endodontic files in digital radiographs before and after employing three image processing algorithms.

OBJECTIVES: Two digital image processing algorithms, one aimed at correction for exponential attenuation and one at correction for visual response, have been developed. The aims of the present study were to test whether digital radiographs processed with these algorithms improve determination of the length of endodontic files and whether such processed radiographs are comparable with the radiographs processed with a default image processing method employed by one commercially available digital intraoral system. METHODS: A dried human skull embedded in an acrylic compound was used for exposing radiographs of the upper and lower premolars and molars with endodontic files (Kerr files size 10 and size 15) positioned to the full length of the roots or 1.5 mm short of it. Radiographs were then processed in three sets. In one set, the radiographs were processed to compensate for exponential attenuation and the response of the human visual system. In the second, the radiographs were processed with the same compensation but with an additional shift in grey levels so that the output luminance in dentin at root tips corresponds to the mean of the luminance range of a computer monitor. In the third, the radiographs were processed with the default processing method in the Sidexis program. Ten viewers evaluated all radiographs. Receiver operating characteristic (ROC) curves were obtained and areas under the curves were calculated. RESULTS: For file size 10, ROC curves for processed radiographs were higher than that for originals, while for file size 15, ROC curves for processed and original radiographs were close to each other. Significant differences were found between processed and original radiographs regarding areas under ROC curves for file size 10 but not between the differently processed radiographs. For file size 15, no significant differences were found. CONCLUSION: Radiographs processed to correct for attenuation and visual response may improve determination of the length of thin endodontic files. Such processed radiographs are comparable with the radiographs processed with the default processing method in the Sidexis program.

Algorithms↗

PubMed2004

Scientific LogAnalyzer: a web-based tool for analyses of server log files in psychological research.

Scientific LogAnalyzer is a platform-independent interactive Web service for the analysis of log files. Scientific LogAnalyzer offers several features not available in other log file analysis tools--for example, organizational criteria and computational algorithms suited to aid behavioral and social scientists. Scientific LogAnalyzer is highly flexible on the input side (unlimited types of log file formats), while strictly keeping a scientific output format. Features include (1) free definition of log file format, (2) searching and marking dependent on any combination of strings (necessary for identifying conditions in experiment data), (3) computation of response times, (4) detection of multiple sessions, (5) speedy analysis of large log files, (6) output in HTML and/or tab-delimited form, suitable for import into statistics software, and (7) a module for analyzing and visualizing drop-out. Several methodological features specifically needed in the analysis of data collected in Internet-based experiments have been implemented in the Web-based tool and are described in this article. A regression analysis with data from 44 log file analyses shows that the size of the log file and the domain name lookup are the two main factors determining the duration of an analysis. It is less than a minute for a standard experimental study with a 2 x 2 design, a dozen Web pages, and 48 participants (ca. 800 lines, including data from drop-outs). The current version of Scientific LogAnalyzer is freely available for small log files. Its Web address is http://genpsylab-logcrunsh.unizh.ch/.

Data Interpretation, Statistical↗

PubMed1998

The effect of sterilization on bending and torsional properties of K-files manufactured with different metallic alloys.

The purpose of this study was to assess the effect of dry-heat or autoclave sterilization on the resistance to fracture in torque and angular deflection and the resistance to bending of K-type files made of nickel-titanium (Nitiflex, Naviflex), titanium (Microtitane) or stainless steel (Flexofile, Flex-R). Ten K-type files of each sort, from size 25 to 40, were tested, according to ANSI/ADA specification 28 (1988) and ISO specification 3630 (1992). Sterilization with dry heat and autoclave slightly decreased the flexibility of files made of stainless steel and nickel-titanium for most of the sizes, although the values obtained satisfied ISO specifications. The files made of titanium showed an increased flexibility after sterilization with autoclave (sizes 30 and 35) and dry heat (sizes 30, 35 and 40). Resistance to fracture varied amongst the five groups of files tested as follows: it decreased in some sizes of stainless-steel instruments, decreased in all sizes of titanium files assessed by the torsional moment, and either increased or decreased in some sizes of nickel-titanium files. All files tested, however, satisfied relevant standards for angular deflection after being subjected to sterilization with an autoclave or dry heat.

Alloys↗

PubMed1991

Development of an integrated filing system for endoscopic images.

A new integrated filing system for endoscopic images has been developed, comprising a main image filing system and subsystems located at different stations. A hybrid filing system made up of both digital and analog filing devices was introduced to construct this system that combines the merits of the two filing methods. Each subsystem provided with a video processor, is equipped with a digital filing device, and routine images were recorded in the analog image filing device of the main system. The use of a multi-input adapter enabled simultaneous input of analog images from up to 8 video processors. Recorded magneto-optical disks make it possible to recall the digital images at any station in the hospital; the disks are copied without image degradation and also utilised for image processing. This system promises reliable storage and integrated, efficient management of endoscopic information. It also costs less to install than the so-called PACS (picture archiving and communication system), which connects all the stations of the hospital using optical fiber cables.

Analog-Digital Conversion↗

PubMed2003

Keeping lists and naming names: habitual patient files for suspected nontherapeutic drug-seeking patients.

Emergency departments commonly keep files of patients who are suspected of frequently visiting them and fabricating symptoms to obtain prescription drugs, usually opioids, for nontherapeutic purposes. Such files have previously been given names such as "frequent flyer file," "repeater log," "kook-book," "problem patient file," "patient alert list," or "special needs file." Little has been written about the ethical, legal, and regulatory considerations that should be taken into account when establishing, maintaining, and using such files. This article explores these issues. The term "habitual patient files" is proposed because it is descriptive without being judgmental.

Confidentiality↗

PubMed1995

Computer files.

From what has been said, several recommendations can be made for users of small personal computers regardless of which operating system they use. If your computer has a large hard disk not specially required by any single application, organize the disk into a small number of volumes. You will then be using the computer as if it had several smaller disks, which will help you to create a logical file structure. The size of individual volumes has to be selected carefully with respect to the files kept in each volume. Otherwise, it may be that you will have too much space in one volume and not enough in another. In each volume, organize the structure of directories and subdirectories logically so that they correspond to the logic of your file content. Be aware of the fact that the directories suggested as default when installing new software are often not the optimum. For instance, it is better to put different graphics packages under a common subdirectory rather than to install them at the same level as all other packages including statistics, text processors, etc. Create a special directory for each task you use the computer. Note that it is a bad practice to keep many different and logically unsorted files in the root directory of any of your volumes. Only system and important service files should be kept there. Although any file may be written all over the disk, access to it will be faster if it is written over the minimum number of cylinders. From time to time, use special programs that reorganize your files in this way.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer Storage Devices↗

PubMed2001

Integrating digital teaching-file systems with off-the-shelf presentation software to facilitate speaker-led conferences.

OBJECTIVE: Develop methods for automated transfer of images and associated text from a teaching-file repository into presentation material for speaker-led conferences. MATERIALS/METHODS: Our institution uses a Microsoft Windows (Microsoft Corp, Redmond, WA) software application to maintain a digital teaching-file database that can store and retrieve content in a case-centric fashion. Virtually any number of images can be stored with any given case. Cases and their associated images can be retrieved via a module that supports searches by American College of Radiology (ACR) code and by free-text Boolean queries on the history, findings, diagnosis, and discussion components of a case. In addition to the software system serving directly as an interactive teaching tool, the digital teaching file itself serves as an image repository and resource for attending radiologists who create their own presentations and lectures. To better support this use, software modules were developed for interprocess communication and automated creation of Powerpoint slides. These modules are fully integrated with the teaching-file software application. A single image or a set of selected images can be automatically made into individual slides with two mouse clicks. Images are automatically centered and optimally sized. A slide title is automatically rendered from the user's preference of the case history or diagnosis (stored with the case), or via the entry of freeform text. We describe the programming techniques that are used, as well as how several features of the operating system and Powerpoint itself can be integrated with a customized software application to facilitate this objective. RESULTS: The creation of presentation-ready Powerpoint slides is fully automated from within our teaching-file application, and the time required to create a presentation compared to the conventional method of manually seeking and inserting files from within Powerpoint itself, on a per-slide basis, is drastically reduced. The benefits are magnified by having all imagery stored within an organized and searchable database system so that desired images can be easily located. CONCLUSION: A digital teaching-file system can serve as a useful image repository for purposes ancillary to direct computerized instruction. Software that supports these uses, such as the automated creation of presentation material for speaker-led conferences, facilitates the radiologist's role as an educator.

Computer-Assisted Instruction↗

PubMed2001

Adobe acrobat: an alternative electronic teaching file construction methodology independent of HTML restrictions.

The goal of the project was to create a method by which an in-house digital teaching file could be constructed that was simple, inexpensive, independent of hypertext markup language (HTML) restrictions, and appears identical on multiple platforms. To accomplish this, Microsoft PowerPoint and Adobe Acrobat were used in succession to assemble digital teaching files in the Acrobat portable document file format. They were then verified to appear identically on computers running Windows, Macintosh Operating Systems (OS), and the Silicon Graphics Unix-based OS as either a free-standing file using Acrobat Reader software or from within a browser window using the Acrobat browser plug-in. This latter display method yields a file viewed through a browser window, yet remains independent of underlying HTML restrictions, which may confer an advantage over simple HTML teaching file construction. Thus, a hybrid of HTML-distributed Adobe Acrobat generated WWW documents may be a viable alternative for digital teaching file construction and distribution.

Computer Communication Networks↗

PubMed1988

Survey concerning international computer files of road accidents.

A survey concerning international harmonization of accident reporting was distributed to 80 experts in accident reporting and analysis. Completed surveys were received from 50 persons in 13 countries; 74% of the respondents had more than 10 years of experience in the field of traffic safety. The main findings of this survey are: (1) 86% of the respondents think that an international computer file of disaggregated fatal-accident data would contribute to understanding of traffic safety, and 84% would use such a file. (2) An international non-fatal-accident file was considered to be of value in research on human factors and accident causation (60%), and in determining black spots in the road network (57%). (3) Police was the most frequently mentioned source of data for both the fatal and non-fatal international data files. Nevertheless, fewer than one-quarter of respondents considered police as the suitable exclusive source of either data. (4) The majority view was that the data for both types of files should come from more than one agency. (5) In the case of the fatal-accident file, 78% of the respondents considered it important that the data be cross-checked with the public health records. (6) The 10 most useful variables for a fatal-accident file were traffic unit type (e.g. car), accident type (e.g. angle), road class, driver age, date/time of day, age of person killed, number of killed persons, number of injured persons, drinking or drug use, and restraint usage of person killed.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidents, Traffic↗

PubMed1984

The influence of file size, cleaning, and time on effectiveness of bead sterilizers.

A controlled study was conducted to determine the influence on disinfection of cleaning endodontic files with either dry gauze or alcohol-saturated gauze prior to placement of the files into a hot bead sterilizer. File size and length of time in the hot bead sterilizer were also investigated. Findings indicated that an alcohol wipe was more effective than a dry wipe except in the largest file tested. Using an alcohol wipe and 3 seconds in a hot bead sterilizer for No. 10 files or 5 seconds for either a No. 30 or a No. 45 file was equivalent in disinfecting ability to 8 seconds and a dry wipe using the same file sizes.

Dental Instruments↗

PubMed1995

Cross-sectional configuration of endodontic files compared with manufacturers' design.

The cross-sectional configuration of seven files at coronal and apical levels were compared with diagrams presented by manufacturers. The presence of cutting edges was also examined. Ground-twisted (K-file, K-Reamer, and K-flex) and machined files (Flex-R, Unifile, S-file, and Hedstrom) were included in #10, #25, and #40. Twelve files of each size and brand comprised the samples. Files were embedded in acrylic, which was then cut in cross-section in the apical and coronal parts of the flutes. These were photographed under a microscope. Six clinicians viewed the slides projected onto a screen for comparison with manufacturers' design and evaluation of visible cutting edges. The inconsistencies were primarily in machined files, smaller sizes, and apical sections of the instruments. Data showed that overall the cross-sections and presence of cutting edges compared well with the designs intended by the manufacturers.

Dental Instruments↗

PubMed1996

Comparison of nickel-titanium and stainless steel hand-file instrumentation using computed tomography.

Computed tomography was used to evaluate root canals prepared by nickel-titanium (Ni-Ti) hand and stainless steel hand endodontic instruments. Thirty-six single-rooted teeth of similar shape and canal size were divided into three groups. The teeth were scanned by computed tomography before instrumentation. In group A, canals were instrumented using a quarter turn/pull technique with K-flex files. In group B, canals were prepared with Ni-Ti hand files (Mity files) using the same technique as group A. Group C was prepared with Ni-Ti hand files (Mity files) using a reaming technique. Instrumented teeth were again scanned using computed tomography, and reformated images of the uninstrumented canals were compared with images of the instrumented canals. Ni-Ti instruments (Mity file) used in a reaming technique caused significantly less canal transportation (p < 0.05), removed significantly less volume of dentin (p < 0.05), required less instrumentation time (p < 0.05), and produced more centered and rounder canal preparations than K-flex stainless steel files used in a quarter turn/pull technique. The computed tomography imaging system used in this study provided a repeatable, noninvasive method of evaluating certain aspects of endodontic instrumentation.

Analysis of Variance↗