Simulated Curved Root Canals Research Articles

OR 17 Variable instrument precurving and transportation in simulated curved root canals: T.A. Svec,* M.M. Wang (UT-Houston Dental Branch, Houston, TX, USA)

OR 17 Variable instrument precurving and transportation in simulated curved root canals: T.A. Svec,* M.M. Wang (UT-Houston Dental Branch, Houston, TX, USA)

Effect of preflaring on canal transportation: Evaluation of ultrasonio, sonic, and conventional techniques

This study evaluated the effect on canal transportation when acrylic canals were preflared with Peeso reamers before the use of ultrasonic, sonic, and hand instrumentation techniques. Twenty resin blocks with simulated curved root canals were shaped with each technique to a size 40 file 0.5 mm from the apical foramen. Ten of the canals were preflared in the cervical region with No. 1 and No. 2 Peeso reamers before instrumentation; 10 canals that were not preflared served as controls. Transportation was measured on the inside canal curvature 3 mm from the canal orifice and 8 mm cervical to the working length, and on the outside canal curvature 1 mm cervical to the working length. Statistical analysis with Student'sttest did not show a significant reduction in canal transportation for the preflared groups. In some areas the amount of transportation was less for the preflared groups; in other areas it was greater.

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.

The effect of endosonic instrumentation in simulated curved root canals

This study evaluated the effects of ultrasonic, sonic, and conventional instrumentation techniques on curved root canals. Fifty resin blocks with curved canals were divided into five groups. Each group was instrumented by one of the following techniques: conventional hand instrumentation, sonic instrumentation using the Medidenta MM3000 unit, sonic instrumentation using the Syntex Endostar 5 unit, ultrasonic instrumentation using the Caulk Cavi-Endo unit, and ultrasonic instrumentation using the Osada Enac OE-2 unit. All preparations were made to the size of a#35 K-type file. Measurements of the amount of transportation of the canal were made at the apical and middle portions of the preparations. The results were significantly different based on statistical analysis of variance. A multiple comparison test revealed that the Medidenta and Caulk systems transported significantly less at the apex of the curved canals than the Syntex system and hand instrumentation techniques. The Medidenta, Syntex, and hand instrumentation transported significantly less in the middle portion of the curved canals than the Caulk and Osada systems. This study evaluated the effects of ultrasonic, sonic, and conventional instrumentation techniques on curved root canals. Fifty resin blocks with curved canals were divided into five groups. Each group was instrumented by one of the following techniques: conventional hand instrumentation, sonic instrumentation using the Medidenta MM3000 unit, sonic instrumentation using the Syntex Endostar 5 unit, ultrasonic instrumentation using the Caulk Cavi-Endo unit, and ultrasonic instrumentation using the Osada Enac OE-2 unit. All preparations were made to the size of a#35 K-type file. Measurements of the amount of transportation of the canal were made at the apical and middle portions of the preparations. The results were significantly different based on statistical analysis of variance. A multiple comparison test revealed that the Medidenta and Caulk systems transported significantly less at the apex of the curved canals than the Syntex system and hand instrumentation techniques. The Medidenta, Syntex, and hand instrumentation transported significantly less in the middle portion of the curved canals than the Caulk and Osada systems.