![]() Middle right: Instrumentation to just short of the apical foramen. Middle left: Instrumentation of the middle third of the canal using a file with 6% taper. Left: The procedure is initiated using the orifice-widener and instrumentation to just short of the curvature of the canal. The file with a taper of 4% can be used up to 2 mm above the apex the 2% taper file is then used to the full working length. Following coronal widening of the canal orifice, the initial depth is prepared with a file with 6% taper. The estimated working length is transferred to the various files, resulting in a crown-down instrumentation technique. Size selection is carried out with the apical “scouting” file: Using the size 8 file, the canal is instrumented using the yellow sequence, increasing the file size by one number at a time until the final apical opening corresponds to a size 25 file tip.Īlpha files for estimating the working length. The 4% file can be used up to 2 mm above the apex, and the 2% file is then used to the full working length. The instrumentation is carried out using the crown-down technique with increasing taper of the instruments. The speed of rotation of the orifice-widening files should not exceed 800 rpm all other instruments are used at a speed of 250 rpm. ![]() This process guarantees the maintenance of sharpness even following repeated sterilization (Schäfer, 2002). Right: Instruments for basic treatment of small (yellow sequence), medium (red sequence), and larger root canals (blue sequence).Īll instruments are coated with a layer of titanium nitride. Using the green sequence, canals are instrumented with an apical scouting file of size 20. Instrument set with additional sizes indicated for larger root canals. This instrument cross section is designed for a high level of fracture resistance. Right above: Pentagonal cross section of the Alpha file. Right: Working end of files with tapers of 2%, 4%, and 6%. Left above: Kite-shaped cross section of the orifice-opening file. Left: Working end of the orifice widener with a large chip space for necessary dentin removal from the canal. The taper is indicated by notches on the instrument shaft: 2% taper file has three notches, 4% taper file has two, and 6% taper file has one notch. ![]() Right: The color coding corresponds to ISO recommendations. The 19-mm long orifice widener exhibits a taper of 10% (.06), making the entire instrument length 22 mm all other files are 25 mm long with a working portion of 13 mm. The negative cutting angle achieves passive dentin removal and prevents excessive cutting into the root canal wall.ĭesign principles of the Alpha file. ![]() This design aims to prevent instrument fracture the tested torque values are the highest in comparison to all other instruments. This makes the introduction of other files into the canal less complicated by reducing the chances of coronal sticking of the files and permits a larger quantity of irrigating fluid to be used to improve the cleaning and antibacterial effect, thus reducing postoperative complications to a minimum.įor the apical finish, instruments with a pentagonal cross-section should be used. This “pre-enlargement” provides improved tactile control and makes possible an improved insertion path with the prebent size 10 K file. Their large chip space makes them a good choice as the first instrument to work with. The files for coronal widening are kite-shaped in cross section with 10% taper. The Alpha files are commercially available in two different cross-sectional conformations. The Alpha system, developed in 2005, consists of NiTi instruments with tapers of 2%, 4%, 6%, and 10%. ![]()
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