The use of mechanical instruments in reciprocation with unequal forward and reverse rotation was introduced in 2008. Reciproc® series of instruments (VDW GmbH, Munich, Germany) were designed specifically for this type of motion.
The present article describes the use of Reciproc® blue instruments for the canal preparation without any prior instrumentation and without a glide path. Only one instrument is needed to enlarge the majority of the canals to an adequate size and taper regardless of the size of the canal, the degree of canal curvature or canal calcification.
The Reciproc® blue system includes 3 instruments, similar to the original Reciproc® series, the Reciproc® blue 25, Reciproc® blue 40 and Reciproc® blue 50, matching paper points, matching gutta-percha cones, and matching gutta-percha obturators (GuttaFusion®) (Fig. 1).
The technique is simple. In the majority of the canals, only one Reciproc® blue instrument is used in reciprocation to complete the canal preparation without the need for hand filing or creating a glide path. The requirements for the access cavity and the straight-line access to the canals, and the irrigation protocols remain unchanged. The use of drills or orifice openers is not required prior to starting the canal preparation with the Reciproc® blue instrument.
The selection of the appropriate Reciproc® blue instrument is based on an adequate radiograph (Fig. 4).
With continuous rotation it is necessary to create a glide path in order to minimize instrument binding and the risk of fracture. Binding is less likely to occur when an instrument is used in reciprocation with unequal forward and reverse angles and with the limited in- and out- movements as described earlier. Therefore, a glide path is not required in the majority of the canals when instruments are used in this manner. It has been shown the incidence of fracture of instruments used in reciprocation with unequal forward and reverse angles and with a pecking motion is very low in comparison to rotary instruments. However, just as with any continuous rotary system, it is possible to use the Reciproc® blue instruments after creating a glide path with for example with a new reciprocating instrument, the R-Pilot® (VDW GmbH, Munich, Germany) (Fig.7) specifically designed for this purpose.
A glide path should be created with the R-Pilot® prior to using the Reciproc® blue in some canals, or for example when the Reciproc® blue instrument stops advancing in the canal or if advancement becomes difficult. In these canals, apical pressure should not be exerted on the Reciproc® blue file. The instrument should be removed from the canal and the canal should be
irrigated. Patency is established to the working length with a #8 file and the R-Pilot® instrument is used to create a glide path to the working length. The Reciproc® blue instrument can then be used safely to the working length. The R-Pilot® instrument is used with the same reciprocating motor and settings, with a light and short pecking motion similar to the use of Reciproc® blue. A glide path can also be created with the R-Pilot to reduce the stresses on the Reciproc® blue instruments for example in canals with difficult access or canals presenting with a curvature in their coronal third (Fig. 8).
If an increased apical enlargement is required, a larger Reciproc® blue instrument, or a nickel-titanium hand or rotary instrument can be used.