Wednesday, December 14, 2011


The stepdown technique may be modified with the use of this range of files described by Buchanan in 1996. The balanced force technique is used as described previously, except that these instruments are used in the opposite rotation to conventional files. It was considered that the crucial part of the balanced force technique is the cutting cycle. Right-handed clinicians (representing some 90% of the work-force) can make this movement more easily in a clockwise direction than anticlockwise. Thus the initial movement to engage the dentine with these files only is a 60  turn anticlockwise, and the balanced force cutting motion is 360  clockwise.  
Following access to and irrigation of the pulp chamber the canal must first be gently explored to length with conventional 2% taper hand files. A gentle watchwinding technique is used with size 08, 10 and 15 files. The tip of the Greater Taper File then acts as a pathfinder rather than as a preparation file.  Using EDTA lubrication paste, the largest file with a blue handle and a taper of 12%, is used first to gain coronal access. When resistance is met the instrument is not forced further apically, but the red handled 10% taper file is used to penetrate further. The yellow handled 8% taper and white handled 6% taper follow in sequence, until the canal is prepared to working length.  The technique is varied according to the clinical situation. In a wide, straight canal, only a single 12% taper file may be required. In a narrow, curved canal, the
clinician may only use the smaller files, alternating them repeatedly to create space for further apical penetration. Before attempting to instrument narrow, curved canals it is again always advisable to use conventional 2% taper instruments from size 08 through to size 20. The tip of the Greater Taper file then acts as a pathfinder, dentine removal occurring at the side of the instrument, not the tip. Once a smooth-tapered canal has been prepared, the clinician may consider it necessary in some cases to enlarge the apical constriction slightly with conventional hand files. The technique is summarised in Table 1, and shown in Figure 13.