Filing Motion Research Articles

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.

Shaping of simulated root canals in resin blocks using the step-back technique with K-files manipulated in a simple in/out filling motion.

A total of 60 simulated root canals in clear resin blocks of various lengths and degree of curvature were prepared by hand with K-files using a step-back enlargement technique. The instruments were manipulated exclusively with a simple in/out filing or rasping motion with no attempt at rotation or twisting. The preparation technique was assessed by instrumentation time, deformation and fracture of instruments, and loss of working distance. The shape of the prepared canals was assessed by direct inspection and from composite photographic prints produced by superimposing negatives of the canals obtained before and after preparation. In general, the preparations were time-consuming and tedious to complete. Deformation and separation of instruments occurred mainly in those canals with short, severe curves. Loss of working distance was a universal finding and was associated to a degree with the straightening of curved canals inherent in their preparation. Prepared straight canals displayed a continuously tapering form being narrowest at their end-point. On the other hand, prepared curved canals were invariably hourglass in shape. Under the conditions of this study the manipulation of K-files in a simple in/out filing motion proved an unsatisfactory method of preparing simulated curved root canals in resin blocks.

Cutting efficiency of endodontic hand instruments. Part 4. Comparison of hybrid and traditional instrument designs

In this study the cutting efficiency of three hybrid designs of endodontic instruments were compared with traditional K-type and H-type files for their ability to enlarge standardized artificial root canals. Sizes #15 through 30 instruments were tested in a clinical manner by serial preparation using a circumferential filing motion as the method of canal enlargement. The relative cutting ability of each group was evaluated in terms of the mean specimen weight loss following serial preparation. The cutting efficiency of each group was reported as the rate of canal enlargement, based on the mean specimen weight loss versus time. Significantly greater cutting efficiency occurred with the newly designed S file and traditional Hedstrom files over other types of hand instruments.

File damage during root canal preparation

The purpose of this study was to determine the frequency of file damage during root canal preparation and to observed any difference in the frequency of damage between United and K-Flex files. Canals of 126 extracted human teeth were prepared with filing motions by 18 sophomore dental students. Eight students used Unitek and 10 used K-Flex files. File damage or separation was evaluated by two endodontists. The rate of damage or separation was low (98 files) compared with previous rates in this laboratory. Most file damage occurred while filling canals in posterior teeth with # 10 files. One file separated for every 3.91 posterior teeth that were filed. The mean number of separated or damage files per student in the K-Flex group was 5.7 while the mean for the Unitek group was 5.13. There was no statistical difference between the two groups. The purpose of this study was to determine the frequency of file damage during root canal preparation and to observed any difference in the frequency of damage between United and K-Flex files. Canals of 126 extracted human teeth were prepared with filing motions by 18 sophomore dental students. Eight students used Unitek and 10 used K-Flex files. File damage or separation was evaluated by two endodontists. The rate of damage or separation was low (98 files) compared with previous rates in this laboratory. Most file damage occurred while filling canals in posterior teeth with # 10 files. One file separated for every 3.91 posterior teeth that were filed. The mean number of separated or damage files per student in the K-Flex group was 5.7 while the mean for the Unitek group was 5.13. There was no statistical difference between the two groups.

Root canal instrumentation with unitek and K-Flex files

The purposes of this study were to determine the effectiveness and any significant differences between K-Flex and Unitek files in maintaining original canal shape during instrumentation. Three-hundred twenty-five canals of extracted human anterior and posterior teeth were prepared by 22 sophomore dental students using circumferential filing motions to make flared preparations. Three endodontists examined pre- and postoperative radiographs to see if length, shape, and foramen position were maintained and to observe any canal perforations. Generally, the canals were well prepared and there were no significant differences between the performances with the two types of files. Perforations were not frequent but when present, they occurred in the apical one-third of the canal.

An electronic tachometer for disk file motion control

An electronic tachometer system used as a velocity transducer for the track-accessing control system of a disk file is described. Rather than employing a conventional moving magnet and fixed-coil velocity transducer, this electronic tachometer combines information from the servo head position signal and from the actuator motor current to generate an accurate measurement of actuator velocity. Transducer bandwidths of several kilohertz, together with good calibration accuracy and linearity, are obtained over the 100:1 dynamic range of 0.013 to 1.3 meters per second.

The Filing and Cataloguing of Motion Picture Film<!--<xref ref-type="other" rid="fn1-10.5594_J11851">*</xref>-->

This paper describes the improved methods of cataloguing and filing motion picture film. While very compact, the film catalogue system permits very rapid location of a single frame of the desired shot.