It has been recognised for some time that nickel-titanium
(NiTi) rotary systems reduce the time required for biomechanical preparation, as well as diminishing the number
of failures related to instrumentation (0). Since their
introduction, numerous NiTi rotary systems have been
added to the arsenal of endodontic instruments. The same
manufacturer can make several designs, in an attempt to
improve the performance of such systems. The ProTaper™ and ProTaper Universal™ systems (Dentsply/
Maillefer, Ballaigues, Switzerland) are an example of this.
Different cross-sectional geometries of rotary instruments are believed to increase cutting efficiency, consequently reducing contact areas and torsional loads (0).
ProTaper™ instruments, in particular, were developed
with a non-radial land design intended for more effective
cutting (0). In addition, these instruments present multiple tapers over the length of their cutting blades that are
designed to allow each instrument to engage a smaller
zone of dentin (0). The ProTaper™ rotary instruments
have a convex triangular cross-sectional design and a
non-cutting safety tip. The basic series of ProTaper™ files
comprises six instruments: three shaping and three finishing files. According to the manufacturer, the auxiliary
shaping file SX should be used to produce more shape in
the coronal portion of the root canal. The shaping file S0
should be used initially up to 0 mm short of the apex and
the shaping files S0 and S0 throughout the working
length (WL) to progressively enlarge the apical third. The
finishing files (F0, F0 and F0) should be used to complete
the apical third of the root canal (0).
The ProTaper™ rotary system has been upgraded to the
ProTaper Universal™ rotary system, which includes
shaping, finishing and retreatment instruments. It incorporates a shallow U-shaped groove at each of its convex
triangular sides in cross-section, trying to improve the
flexibility of the larger instruments.