Peet J van der Vyver and Michael J Scianamblo illustrate the use of Protaper Next instruments in difficult and challenging endodontic cases

Recently, the Protaper Next system (Dentsply/Maillefer) was launched into the dental market. In part one of this series, published in December’s issue of Endodontic Practice, the authors outlined the clinical guidelines for the use of the Protaper Next instruments. There are five instruments in the system but most canals can be prepared by using only the first two instruments. The first instrument in the system is the Protaper Next X1, with a tip size of 0.17mm and a 4% taper. This instrument is used after creation of a reproducible glide path by means of hand instruments or rotary Pathfiles (Dentsply/Maillefer). The Protaper Next X1 is always followed by the second instrument: the Protaper Next X2 (0.25mm tip and 6% taper). The Protaper Next X2 can be regarded as the first finishing file in the system as it leaves the prepared root canal with adequate shape and taper for optimal irrigation and root canal obturation. The PTN X1 and X2 have an increasing and decreasing percentage tapered design over the active portion of the instruments. The last three finishing instruments are the Protaper Next X3 (0.30mm tip with 7% taper), Protaper Next X4 (0.40 mm tip with 6% taper) and the Protaper Next X5 (0.5mm tip with 6% taper). These instruments have a decreasing percentage taper from the tip to the shank. The Protaper Next X3, X4 and X5 can be used to either create more taper in a root canal or to prepare larger root canal systems. The advantages of the Protaper Next system include: • The instruments are manufactured from M-Wire that contributes towards more flexible instruments, increased safety and protection against instrument fracture (Gutmann, Gao, 2012) allowing the clinician to treat more complex root canal systems with a high level of success • The instruments have a bilateral symmetrical rectangular cross section with an offset from the central axis of rotation (except in the last 3mm of the instrument, D0-D3) creating an asymmetric rotary motion. The exception is the Protaper X1, which has a square cross section in the last 3mm to give the instruments a bit more core strength in the narrow apical part. The asymmetric rotary motion allows the instrument to experience a rotational phenomenon known as precession or swagger (Scianamblo, 2011). According to Van der Vyver and Scianamblo (2013), the benefits of this design characteristic include: 1. It further reduces (in addition to the progressive tapered design) the engagement between the instrument and the dentine walls because only two cutting points make contact with the canal wall at any time. This will contribute to a reduction in taper lock, screw-in effect and stress on the file 2. It ensures debris removal in a coronal direction because the off-centre cross-section allows for more space around the CPD Aims and objectives This clinical article aims to provide clinical guidelines for the use of Protaper instruments in complex and challenging endodontic cases. CLINICAL