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PubMed1992

Observations of acoustic streaming fields around an oscillating ultrasonic file.

The steady acoustic streaming generated around straight and precurved oscillating ultrasonic files driven by the Piezon-Master 400 unit was examined in the free field and in small channels using a stereomicroscope. In addition, the effect of file-wall contact on streaming production was also investigated. The results indicated that the ultrasonic files can generate acoustic streaming both in the free field and in the small channel. Higher velocity streaming was observed when smaller size files were employed and when the file was precurved. Light file-wall contact did not totally inhibit streaming while severe file-wall contact inhibited movement of the file and, as a result, no streaming was observed. The positions and length scales of the streaming vortices appeared to be influenced by the presence of boundaries. In the free field, two rows of vortices were situated along the sides of the file while in the small channel, the vortices were positioned above the surface of the file. These results indicated that it is possible for acoustic streaming to occur in a confined space as in a root canal provided that severe file-wall contact is avoided. It is therefore recommended that light filing or allowing the file to freely vibrate during some stage of treatment should be carried out in order to generate streaming in the root canal.

Humans↗

PubMed1996

Taper and stiffness of sonic endodontic files.

The aims of this investigation were to measure the thickness and taper of the different files (Heliosonic 15-40. Shaper 15-40 and Rispisonic 1-6) supplied with the MM1500 sonic instrument and relate this to their stiffness. The diameter of the files (n = 5 for each file type) was measured at 2 mm intervals using light microscopy and a calibrated graticule (mag x 120). A model system was developed for the stiffness testing. The file was held 3 mm from its tip and the load in g required to produce a 45 degrees deflection of the file was recorded. Measurements of file diameter showed that the width of the Heliosonic and Shaper increased in a linear manner and that the file taper was the same for increasing file sizes in accordance with ISO recommendations. The Rispisonic files however showed differing widths and degrees of taper which were not consistent with ISO standards. The stiffness testing results showed the Heliosonic files to be less flexible than the Rispisonic and Shaper files for all sizes (ANOVA, p < 0.001). The differences in stiffness of the Heliosonic, Shaper and Rispisonic files were due to the variation in cross sectional area of metal. In conclusion sonic endodontic files do not have the same taper and stiffness.

Analysis of Variance↗

PubMed2005

Contamination of patients' files in intensive care units: an indication of strict handwashing after entering case notes.

BACKGROUND: The extent to which bedside patients' files become contaminated and the range of bacterial flora attributable to contamination in high-risk areas of the hospital are not known with certainty. The aim of the present study was to determine the degree of contamination of the patient's files and also to analyze and compare the spectrum of contaminant bacterial flora between the intensive care unit (ICU) and surgical wards, the 2 most high-risk areas for nosocomial transmission of infection. METHODS: Microbiologic samples were collected from the exposed outer surface of the patients' files kept bedside in the ICU and surgical wards with sterile swabs moistened with sterile normal saline. Swabs were cultured within an hour of collection on blood agar and MacConkey's agar plates, which were incubated at 37 degrees C for 48 hours. Gram-negative bacilli were identified by Gram's stain, catalase, oxidase tests, and API 20E and API 20NE. Staphylococcus species were identified by Gram's stain, catalase test, and tube coagulase test. Antibiotic susceptibility of the isolated bacteria was determined by the disk diffusion technique according to the criteria of National Committee for Clinical Laboratory Standards (NCCLS). RESULTS: In ICU, 85.2% (87/102) and, in surgical wards, 24.7% (22/89) of patient's files were found to be contaminated with pathogenic and potentially pathogenic bacteria (OR, 17.664; 95% CI: 8.050-39.423; P < .0001). Pseudomonas aeruginosa was the most commonly isolated bacteria (32.3%, 33/102) in ICUs, whereas Staphylococcus aureus was the peak contaminant (11.2%, 10/89) of the files in surgical wards. Methicillin-resistant Staphylococcus aureus (MRSA) was isolated from 6.8% (7/102) of ICU patient's files, whereas only 1.1% (1/89) of patient's files in surgical wards were contaminated with MRSA (OR, 6.484; 95% CI: 3.215-13.463; P < .0001). The multidrug-resistant P aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, and Serretia marcesens isolated from the patient's files had the same antibiotic resistance pattern as of these bacteria isolated from the patients. CONCLUSION: The majority of the patient's files in ICUs were contaminated often with multidrug-resistant bacteria and even MRSA. Contaminated files could be a source of transmission of infection. To prevent this, handwashing practice should be strictly followed after attending the patient and before entering the case notes in the patient's file. The maintenance of good hand hygiene by the health care workers (HCWs) after handling contaminated files should perhaps be the most prudent approach to prevent patient-patient transmission of infection in high-risk areas including ICU and surgical wards.

Cross Infection↗

PubMed1990

Comparison of endodontic file tip quality.

Tip angulation and four visual characteristics denoting manufacturing quality of endodontic files were studied. One-hundred eighty K-type, Hedstrom, and Flex-type files from two manufacturers (Kerr and Mallefer) were evaluated. Photomicrographs (x 115) were made of each file. Two evaluators examined the photomicrographs. Tip angulation was studied to determine if files were compliant with ANSI/ADA Specification Nos. 28 and 58. The four visual characteristics compared in the study were symmetry versus asymmetry, smooth versus irregular, tip configuration, and shoulder configuration. Statistical analysis was made using the chi-square method. Mallefer files appear to be more in conformity with specifications for tip angle and more meticulously manufactured than Kerr files. Kerr Hedstrom files appear to conform less often to tip angle specifications than Kerr K-type or K-Flex files. K-type and Flex-type file tips appear to be better manufactured than Hedstrom file tips. Certification status of a file manufacturer did not correlate with a higher level of compliance with tip angulation specifications or with a better machined file tip.

Chi-Square Distribution↗

PubMed1992

Comparison of six files to prepare simulated root canals. 2.

A total of 300 simulated root canals of various angles and positions of curvature in clear resin blocks were prepared by hand using either K-files, K-Flex files, Flexofiles, Flex-R files, Hedstrom files or Unifiles. Each file type was used to prepare 50 canals employing a linear filing motion and an anticurvature stepback technique. Part 2 of this two-part report describes the efficacy of the files in terms of the prevalence of canal aberrations, the amount and direction of canal transportation and the overall postoperative canal shape. Hourglass shaped canals were found in 4.5% of curved canals, the majority of these being created by K-files and K-Flex files. Perforations were seen in 6.3% of curved canals, the majority being produced by Flex-R files and K-files. Excessive removal of material from along the inner aspect of the canal curve occurred in 10.4% of canals, by far the majority being created by Hedstrom files. Transportation of canals was a consistent finding with all instruments. Two-way analysis of variance revealed how significant differences in the absolute magnitude of transportation occurred between instruments, between canal types and by an interaction between instrument and canal type. In general, transportation was towards the outer aspect of the canal curve at the end-point of preparation and the zip and elbow, but towards the inner aspect at the beginning of the curve. Further towards the orifice, transportation reverted to the outer aspect of the canal curve.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMedDate not supplied

A new approach to the film library: time-unit filing.

The installation of a new radiology information system (RIS) at Children's Hospital Medical Center of Akron in Akron, Ohio, took the radiology department into a new world of technology, but raised issues we never anticipated. The major problem the new RIS forced the department to overcome was how to eliminate the film file's reliance on a proprietary radiology numbering system. Previously, the department had used its own numbering system--a proprietary x-ray number--to file film jackets and had used the hospital-issued medical record number to access patient and payer information from the hospital information system. It became clear that we should use a single number--the medical record number--to access all data, but we wondered how that would affect our film file room. An RIS consultant suggested that we consider filing films by last date of service, a system called "time-unit filing." Time-unit filing means keeping the most recent two-weeks worth of films in the main file room. They are organized by gender in blue or pink jackets and marked alphabetically by the patient's last name in a way that makes mis-files easy to see. If a patient's film jacket is activated again, it is refiled in the current two-week time unit. Inactive jackets remain in their two-week time unit indefinitely. Time-unit filing has had many benefits for the radiology department at Children's Hospital Medical Center of Akron: fewer mis-files, less time needed for filing and searching, and successful implementation of the new RIS.

Evaluation Studies as Topic↗

PubMed2007

An integrated approach to a teaching file linked to PACS.

To meet the educational needs of a medical imaging department with a strong teaching commitment, a teaching file that uses digital data supplied by the institutional picture archiving and communications system (PACS) was required. This teaching file had to be easily used by the end users, have a simple submission process, be able to support multiple users, be searchable on all data fields, and implementing the teaching file must not incur any additional software or hardware costs. The teaching file developed to address this problem takes advantage of the database structure and capabilities of several components included in the commercial PACS installed at the hospital. MS Access is used to seamlessly integrate with the digital imaging and communication in medicine (DICOM) database of a normal work station that is part of the PACS. This integration allows relevant patient and study demographics to be copied from images of interest and then to be stored in a separate database as the back-end of the digital teaching file. When images for a particular teaching file case need to be reviewed, they are automatically retrieved and displayed from the main PACS database using an open application programming interface (API) connection defined on the PACS web server. Utilizing this open API connection means the teaching file contains only the relevant demographic information of each teaching file case; no image data is stored locally. The open API connection allows access to imaging data usually not encountered in a teaching file, allowing more comprehensive imaging case files to be developed by the radiologist. Other advantages of this teaching file design are that it does not duplicate image data, it is small allowing simple ongoing backup, and it can be opened with multiple users accessing the database without compromising data access or integrity.

Computer-Assisted Instruction↗

PubMed1992

Effect of precurving on the performance of endosonic K files.

This study compared the performance of precurved and straight endosonic files. Size 15, 20, and 25 endosonic K files were precurved to different degrees (20 to 90 degrees) and the resultant oscillatory pattern showed no significant difference compared with corresponding straight files. Endovue blocks were prepared with either a #15, 20, or 25 endosonic file which was either straight or precurved. Those blocks prepared with precurved files had a continuous taper while blocks prepared with straight files had constrictions along their lengths. Finally, a curved root of a human natural tooth had windows prepared along its length so that the oscillatory pattern of the file could be observed. The precurved file oscillated more freely than a straight file as observed by the presence of antinodes along the file and the accumulation of dentin chips within the canal. The results of this study suggest that it is advantageous to precurve endosonic files before using them in curved canals.

Dental Cavity Preparation↗

PubMed1990

Machining efficiency of Flex-R, K-Flex, Trio-Cut, and S Files.

Many root canal instruments with several different designs have been introduced during recent years. This article evaluates the machining properties of four such instruments: the Flex-R, K-Flex, Trio-Cut, and S file. There are large variations in the machining properties of these instruments. The results are comparable to findings when evaluating conventional root canal files which show that the Hedstrom file is much more efficient when considering removal of material than the K file. The Flex-R file, K-Flex file, and Trio-Cut file are similar in design. The two former brands perform in a similar fashion, while the Trio-Cut file is less efficient than any of the evaluated K files. The S file performs as a Hedstrom file which can be expected from its similarity in design to that instrument.

Equipment Design↗

PubMed2006

[Providing medical files to patients: analysis of 52 requests].

BACKGROUND: Since enactment of a statute on 4 March 2002 to allow patients direct access to their medical files, the number of requests for these files has increased substantially. The objective of this survey was to learn the patients' motivations for requesting files, what they did with them once they received them, and the effects of this direct access on the patient and on the relationship and confidentiality between physician and patient. METHODS: A questionnaire was sent to 100 persons randomly selected among patients requesting their medical file from the Dijon University Hospital Center after the new law became effective. RESULTS: The response rate to this survey was 58%. In 75% of the cases, patients requested their own medical files. Their reasons varied: curiosity (38%), transfer of the file to another physician (35%), disagreement with the medical team (12%), death of a family member (10%). After receiving the file, 35% of the respondents read it with a physician and 13% with their attorney. In two thirds of the cases, the medical files were transmitted directly to a third party: physician (51%), attorney (34%), or insurance company (20%). The file provided patients with the information they wanted in 79% of cases and allowed them to sue the physician in 12%. Only a quarter of the persons requesting files met with the physician concerned before making their request. CONCLUSION: The disclosure of secret medical information can lead to serious consequences to patients, of which they are not necessarily aware. This may require that clear information about patient-doctor confidentiality be provided to persons requesting files.

Disclosure↗

PubMed2005

A study of visual and blood contamination on reprocessed endodontic files from general dental practice.

OBJECTIVE: This study examined methods used for reprocessing endodontic instruments in general dental practice and determined the degree of residual visual contamination and blood contamination on 250 reprocessed files collected from 25 general dental practices. MATERIALS AND METHODS: A questionnaire was administered to 25 general dental practitioners to obtain information on the re-processing of used endodontic files. Ten files which had been used and reprocessed were also collected from each practice. These were examined visually under a dissecting light microscope for residual contamination and then tested for blood deposits using the Kastle-Meyer test. RESULTS: Nineteen of the 25 practices used stainless steel hand files. No practitioners used endodontic files as single use devices. Ninety-two per cent of the practitioners discarded and replaced files when they were bent or damaged. Several decontamination methods were reported. The two combinations employed most frequently were manual cleaning and autoclaving or manual cleaning, followed by ultrasonic cleaning and autoclaving. Of the 250 files, 75% showed some degree of visual contamination and seven percent tested positive for residual blood. Blood contaminated files were significantly more heavily contaminated when examined visually. Large variations were found in residual contamination of files collected from practices using the same methods of decontamination. CONCLUSIONS: While all practitioners re-used endodontic files, the variations in decontamination methods reported indicate a lack of clarity on best practice. This study demonstrates that endodontic files are not reliably decontaminated by methods currently employed in dental practice.

Blood↗

PubMed2002

The effect of instrument type and preflaring on apical file size determination.

AIM: The aim of this study was to investigate the effect of instrument type (K-files and Lightspeed (LS) instruments) and the impact of preflaring on the first file size that binds at working length (WL) in a range of canal types of varying sizes and curvatures. METHODOLOGY: One hundred and twenty-one canals from 60 extracted intact human maxillary and mandibular premolars and molars were utilized. After standard access cavities, a size 6 K-file was inserted into each canal until the tip of the file was visible outside the apical foramen. WL were set 0.5 mm short of these measurements. Each canal was sized using consecutively larger K-files and hand-held LS instruments until one bound at WL. The file sizes were recorded. The same procedures were repeated after coronal and middle third flaring using Profile rotary instruments. RESULTS: Statistical analysis (univariate analysis of variance: ANOVA) showed that overall, the estimate of mean apical diameter with the LS instrument was larger than with the K-file by 9.4 x 10(-2) mm (P < 0.001; 95% confidence interval: 8.7 x 10(-2), 10.2 x 10(-2)), i.e. almost 2 ISO file sizes larger. Flaring of the cervical and middle thirds of the canal had an impact on apical sizing by both types of instruments, with an average increase of 5.3 x 10(-2) mm (P < 0.001; 95% confidence interval: 4.5 x 10(-2), 6.0 x 10(-2)), i.e. approximately 1 ISO file size larger. CONCLUSIONS: Preflaring and use of hand-held LS instruments resulted in an increase in the instrument size that bound at WL. If an operator wishes to determine an accurate master apical file size, canal orifice enlargement should be performed first before the placement of the assessment file.

Analysis of Variance↗

PubMed2004

Assessment of elemental composition, microstructure, and hardness of stainless steel endodontic files and reamers.

The purpose of this study was to determine the elemental composition, microstructure, and hardness of commercially available reamers, K files, and H files. Five instruments of each type from different manufacturers (Antaeos, FKG, Maillefer, Mani, and Micromega) were embedded in epoxy resin along their longitudinal axis. After metallographic grinding and polishing, the specimens were chemically etched and their microstructure investigated under an incident light microscope. The specimens were studied under a scanning electron microscope, and their elemental compositions were determined by energy dispersive X-ray microanalysis. The same surfaces were repolished and X-ray diffraction was performed. The same specimen surface was used for the assessment of the Vickers hardness (HV200) by using a microhardness tester with a 200-g load and 20-s contact time. The hardness results were statistically analyzed with two-way ANOVA and Tukey's test (a = 0.05). All files demonstrated extensively elongated grains parallel to longitudinal file axis because of cold drawing. The elemental composition of Maillefer and Mani reamers, Antaeos K files, and Mani H files were found in the range of AISI 303 SS, whereas all the rest were determined as AISI 304 SS. Two different phases (austenite SSt and martensite SSt) were identified with X-ray diffraction for all files tested. The results of hardness classified reamers in the following decreasing order (HMV200): Micromega = 673 +/- 29, Mani = 662 +/- 24, Maillefer = 601 +/- 34, Antaeos = 586 +/- 18, FKG = 557 +/- 19, and the K files (HV200): FKG = 673 +/- 16, Mani = 647 +/- 19, Maillefer = 603 +/- 41, Antaeos = 566 +/- 21, Micromega = 555 +/- 15, and the H files (HMV200): Mani = 640 +/- 12, FKG = 583 +/- 31, Maillefer = 581 +/- 5, Antaeos = 573 +/- 3, Micromega = 546 +/- 14. Although only two stainless steel alloys were used for the production of endodontic files, the differences in hardness are independent to the alloys used, implying that other factors, such as the production method or the thermomechanical history of the alloys, play an important role on the mechanical properties of endodontic files.

Acid Etching, Dental↗

PubMed2005

A comparison of torque required to fracture rotary files with tips bound in simulated curved canal.

The purpose of this study was to compare torque force and rotation needed to fracture three types of nickel titanium alloy rotary instruments in a simulated curved root canal space that were bound at the file tip. Files of similar size tips were studied. The files studied were ProFiles with 0.04 taper diameters of 15, 20, 25, 30, 35, 40, 45; 0.04 ProFile GT sizes 20, 30, 40; and ProTaper files sizes S1, S2, F1, F2, and F3. All files were 25 mm in length. Unwinding was defined as the rotation in degrees it took for a file to fracture after the first evidence of permanent deformation. All files exhibited permanent deformation before breaking, with the ProFile GT files demonstrating the greatest unwinding. The #45 0.04 ProFile withstood the most force while the #20 ProFile GT required the least amount of force before beginning to exhibit permanent deformation. The S1 and S2 ProTaper files fractured with so little rotation that no extended data were recorded. Generally, as the file diameter increased, the force needed to begin unwinding also increased. Also, as the file diameter increased, the force needed to fracture also increased.

Analysis of Variance↗

PubMed1989

Shaping of simulated root canals in resin blocks using files activated by a sonic handpiece.

A total of 180 simulated root canals in clear resin blocks with various lengths and degree of curvature were prepared by either Heliosonic, Rispisonic or Shaper files activated by a sonic handpiece. Each file type was used to prepare 60 canals employing an in/out, circumferential filing motion. The efficacy of the sonic handpiece and the three file designs were assessed by instrumentation time, deformation and fracture of instruments and loss of working distance. The shape of the prepared canals was assessed by direct observation and from composite photographic prints produced by super-imposing negatives of the canals obtained before and after preparation. Overall, canal shaping with the Rispisonic and Shaper files was rapid and efficient whilst that with the Heliosonic files was slower and ineffective. With each file type, prepared straight canals displayed a continuously tapering form that was narrowest at their end-point. The majority of curved canals prepared with Heliosonic files were hourglass in shape whilst the majority prepared with the Rispisonic and Shaper files were tapered. Zips and elbows were only created with Rispisonic and Shaper files in those canals with very short, acute curves. Under the conditions of this study the use of Rispisonic and Shaper files activated by a sonic handpiece proved a satisfactory method of shaping simulated root canals in resin blocks.

Dental Cavity Preparation↗

PubMed1997

Comparison of two stainless steel files to shape simulated root canals.

The aim of this study was to compare the shaping ability of two stainless steel files using simulated canals. A total of 80 simulated canals of various angles and positions of curvature were prepared by hand using either Mani K-Files or Micro Mega K-Files. Following orifice enlargement each file type was used to prepare 40 canals employing a linear filing motion and an anticurvature stepback technique. Pre- and post-operative longitudinal images of the canals were taken with a video camera and stored and manipulated in a computer with image analysis software. The presence of canal aberrations and the amount of material removed as a result of preparation were determined from composite images of superimposed pre- and post-operative views. Overall, canal preparation with Mani K-Files was significantly quicker (P < 0.005) and was associated with fewer instrument failures. Zips and elbows were observed in 70% of specimens with significantly more (P < 0.05) occurring following preparation with Micro Mega K-Files. Mani K-Files created significantly more (P < 0.01) danger zones. Micro Mega K-Files created significantly wider (P < 0.001) zips with significantly more (P < 0.01) resin removed from the outer aspect of the curves and, thus, significantly more (P < 0.01) transportation. Canal shape had a significant influence on preparation time (P < 0.001), the incidence of zips (P < 0.05) and danger zones (P < 0.005), the width of zips (P < 0.001) and transportation at the zips (P < 0.001). Under the conditions of this study, Mani K-Files were more effective than Micro Mega K-Files and produced canals with better shapes. Original canal shape had a substantial influence on the outcome of shaping procedures.

Analysis of Variance↗

PubMed1992

Effectiveness of different endodontic files for preparing curved root canals: a scanning electron microscopic study.

In this study, the effect of using four endodontic files from different manufacturers on the final shape of 80 prepared curved root canals of extracted single-rooted teeth were comparatively analyzed with scanning electron microscopy. The instruments tested were Tri-files, Flex-R files, Flexofiles and conventional K-type files. All 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 was performed with a size 30 file. Shaping effectiveness of the tested files was qualitatively evaluated in terms of respect for conservation of the apical constriction and the presence or absence of ledging, specially in the apical third of the root canals. A well-centered and tapered preparation without apical transportation or ledging was detected when Tri-file or Flex-R files were used. Conversely, the use of Flexofile or conventional K-type files resulted in frequent alteration of the initial pattern of the root canals, showing an hour-glass preparation with alteration of the apical constriction and ledge formations.

Dental Cavity Preparation↗

PubMed1994

Some observations on the breakage of ultrasonic files driven piezoelectrically.

The incidence of breakage of Piezon-Master ultrasonic K files were evaluated. Three groups of unused files were subjected to three treatments, namely; free vibration in air without irrigation, free vibration in root canal while minimizing contact with the wall of canal in the presence of irrigation and light filing in root canal with free flow of irrigation. Cavitation produced by files in contact and free of contact with a glass surface was examined in order to observe the relationship between cavitation defects and breakage. In addition, the fractured and unfractured files were examined under a scanning electron microscope for the presence of cavitation pits. The results indicated that more files broke in air. In water, a higher incidence of breakage occurred when files were allowed to freely vibrate while no breakage occurred when the files were used in filing. All files generated cavitation which resulted in pitting of their surfaces. However, it was considered unlikely that the pits contributed to fracture. Fatigue cracks which could be the result of the manufacturing process were observed at some of the corners of the cross sections of the fractured files and could be the main contributory factor to fracture.

Chemical Phenomena↗