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Endo Tribune Asia Pacific Edition

18 Endo Tribune Asia Pacific Edition | 11/2016 ENDO NEWS with a cutting tip being more dangerous that a non-cutting pilot tip. While reciprocation with NiTi instruments have become very popular in recent years, with a sig- nificant number of published ar- ticles, some of these studies have shown that there is also inherent disadvantages in the reciprocating movements. It is well known that a small inadvertent extrusion of debris and irrigants into the peri- apical tissues is a frequent com- plication during the cleaning and shaping procedures, both with manual stainless steel and nick- el-titanium rotary instrumenta- tion techniques.29,30 However, re- cent studies have shown that commercially available reciprocat- ing instrumentation techniques seem to significantly increase the amount of debris extruded beyond the apex31,32 and, consequently, the risk of postoperative pain. A clini- cal study comparing Reciproc and NiTi rotary instruments has also confirmed these findings.33 Since reciprocation movement is formed by a wider cutting angle and a smaller releasing angle, while ro- tating in the releasing angle, the flutes will not remove debris but push them apically. Reciproc and WaveOne motions are very similar (even if not precisely disclosed by manufacturers),andthisfactcould also explain the higher incidence and intensity of postoperative pain that has been found in recent re- search studies.33,34 Moreover, both WaveOne and Reciproc techniques use a quite rigid, large single-file of increased taper (usually 08 taper, size 25), which is directed to reach the apex. In many cases, in order to reach the apical working length, reciprocat- ing instruments are used with api- cally directed pressure, which pro- duces an effective piston to propel debris through a patent apical fora- men, and possibly directing debris laterally, making canal debride- ment more difficult. Since instru- ments are commonly used with- out first performing preliminary coronal enlargement, this may result in a greater engagement of the file flutes and consequently may produce more torque and/or applied pressure on the file. More- over, the cutting ability of a recip- rocating file is decreased when compared to continuous rotation. Debris removal is also less, thus in- creasing the frictional stress and torque demand on the file, due to entrapment of debris within the flutes. To reduce this tendency some authors have advocated the use of NiTi rotary glide path in- struments, before using a Wave- One or Reciproc instruments, but in this case the overall technique is no longer a single file technique but a more complex and more costly technique which utilises two different types of Niti instru- ments, glide path instruments and then shapers.35,15 TF Adaptive The TF Adaptive technique has been proposed in order to maximise the advantages of re- ciprocation, while minimising its disadvantages. By using a unique, patented motion, the innovative TF Adaptive Motion technology, together with an original three-file technique, most clinical cases can be treated effectively and safely (Fig. 2). TF Adaptive employs a pat- ented unique motion technology, which automatically adapts to in- strumentation stress, when used in the Elements Motor while in TF Adaptive setting (Fig. 3). When the TF Adaptive instrument is not (or very lightly) stressed in the canal, the movement can be de- scribed as a continuous rotation, allowing better cutting efficiency and removal of debris. The cross- sectional and flute design are meant to perform at their best in a clockwise motion. More precisely, it is an inter- rupted motion with the following CW-CCW angles: 600–0°. This in- terrupted motion is as effective as continuous rotation in lateral cut- ting, allowing optimal brushing or circumferential filing for better debris removal in oval canals. This interrupted motion also min- imises iatrogenic errors by reduc- ing the tendency of ‘screwing in’ (aka pull down), that is commonly seen with NiTi instruments of great taper that are used in contin- uous rotation. On the contrary, while nego- tiating the canal, due to increased instrumentation stress and metal fatigue, the motion of the TF Adap- tive instrument changes into a re- ciprocation mode, with specifically designed CW and CCW angles that may vary from 600–0° to 370–50° (Fig. 4). These angles are not con- stant, but vary depending on the anatomical complexities and the intracanal stresses placed on the instrument. This ‘adaptive’ motion is therefore meant to reduce the risk of intracanal failure, without affecting performance, due to the fact that the best movement for each different clinical situation is automatically selected by the Adaptive motor. It is quite interest- ing that the clinician will hardly perceive the differences in the changing motion, due to a very so- phisticated algorithm, which per- mits a smooth transition between the changing angles. As far as disadvantages of reciprocation are concerned, TF Adaptive motion is a reciprocating motion with cutting angles (CW angles) much greater than Wave- One/Reciproc movements. This results in the TF Adaptive instru- ment is working for a longer time with a CW angle, which allows bet- ter cutting efficiency and removal of debris (and less tendency to push debris apically and laterally), because the flutes are designed to remove debris in a CW rotation. This results in TF Adaptive taking advantage of the use of a motion that is more similar to continuous rotation for optimal debris re- moval. There are obviously some changes in the angles depending on canal anatomy (the more com- plex, the smaller the CW angle), but they do not seem to significantly influence the overall result. On the contrary, these changes influence resistance to metal fatigue, since TF instruments used with Adap- tive motion were found to have superior resistance to cyclic fatigue when compared to the same TF instruments used in continuous rotation.36 As mentioned before, flexibil- ity is a fundamental property to minimise iatrogenic errors while negotiating canals, both in recip- rocation and in continuous rota- tion. The use of a reciprocating movement, therefore, does not sig- nificantly help a NiTi instrument of greater taper to negotiate curved canals with no iatrogenic errors. It mainly helps to reduce instrumentation stress and the risk of intracanal failure. In addi- tion, a study aimed to compare the frequency of dentinal microcracks after root canal shaping with two reciprocating (Reciproc and Wave- One) and one combined continu- ous reciprocating motion Twisted Files Adaptive (TFA) rotary system. Ninety molars were chosen and divided into three groups of 30 each. Root canal preparation was achieved by using Reciproc R25, Primary WaveOne and TFA sys- tems. All the roots were horizon- tally sectioned at 15, 9 and 3 mm from the apex. The slices were then viewed each under a micro- scope at x25 magnification to de- termine the presence of cracks. The absence/presence of cracks was recorded, and the data were analysed with a Chi-square test. The significance level was set at P<0.05. The results found that instrumentation with Reciproc produced significantly more com- plete cracks than WaveOne and TFA (P = 0.032). The TFA system produced significantly less cracks then the Reciproc and WaveOne systems apically (P = 0.004). The study concluded that within the limits of this study, the TFA system caused less cracks then the full reciprocating system (Reciproc and WaveOne). Single-file recipro- cating files produced significantly more incomplete dentinal cracks than full-sequence adaptive ro- tary motion.39 The TF Adaptive technique is basically a three file technique, designed to treat the majority of cases encountered in clinical prac- tice. Available are two sets of three file systems, one for small, calcify- ing and severely curved canals and one system for more ‘standard’ and larger canals, allowing ade- quate taper and increased apical preparation in both scenarios. The number of instruments within each sequence can also vary and adapt to canal anatomy, with the last instrument of the sequence used only when a greater apical enlargement is needed due to larger original canal dimensions and/or enhanced final irrigation techniques. The sequences are also different in their shaping con- cepts. Each file of the sequence being used is taken to full working length in a ‘crown down’ manner so that the root canal wall is in- ternally sculpted incrementally, allowing dentin debris and tissue to be evacuated coronally rather than to be pushed apically. This may reduce the risk of canal block- age and the extrusion of debris into the apical tissues. The SM 1 file (single colour band green, 04 taper 20 tip size) is an excellent flexible Glide Path file which may be used with either sequence to pre- enlarge the canal thereby decreas- ing instrument stress for the next larger size file in sequence. This also allows better maintenance of the original canal trajectory (Figs. 2 & 5). The final apical enlargement with a size #35 file is not only meant to allow the use of the Endovac (EndoVac Kerr Endodontics, Orange, CA) irrigation technique, but to improve canal shaping by touching more canal walls. Figure 6 clearly shows how improved and deeper the apical one-third shape is when a 06 taper 35 tip instru- ment follows a 08 taper 25 tip in- strument. This is why in the ma- jority of cases two instruments are much better than a single file technique, provided that the sec- ond instrument is a flexible one. The superior flexibility allowed by the use of TF technology permits TF Adaptive to follow these crite- ria, and safely enlarge canals with minimal risk of iatrogenic errors like tooth weakening and canal/ apical transportation. The use of a more rigid alloy would have not made this possible, especially in curved canals.”15 TF Adaptive technique TF Adaptive is an intuitive, color-coded system designed for efficiency and ease of use. The colour-coded system is based on a traffic light. The first instrument in sequence is green. The second instrument in sequence is yellow and the third instrument in se- quence, if required, is red. Green means go. Yellow means continue or stop. Red means stop (Fig. 2). Fig. 6: Deep shaping. The clinical use of a second instrument (06/35) after the 08/25 significantly increases the preparation in the apical one third, improving the quality of canal shaping and allowing room for enhanced irrigation. This will also al- low the use of the apical negative pressure devices such as the EndoVac to safely deliver abundant quantities of sodium hy- pochlorite to the apex without the risk of apical extrusion.—Fig. 7: M4 Safety Handpiece. Fig. 8: TFTM Adaptive Technique Card. Size and Sequence Determination.—Fig. 9: EndoVac Apical Negative Pressure Irrigation System. The Master Delivery Tip (MDT) accommodates different sizes of syringes filled with irrigant, the macro cannula is attached to the autoclavable aluminum hand piece and the micro cannula is attached to an autoclavable aluminum finger piece. The macro cannula, the micro cannula and the MDT are connected via clear plastic tubing. The tubes are connected to the high volume suction of the dental chair via the Multi-Port Adaptor. 6 7 8 9 67 89

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