Reciprocating instruments in endodontics
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The document discusses the history and development of reciprocating systems for shaping root canals. It traces the evolution from early systems that used large, equal angles of rotation to modern single-file systems like WaveOne and Reciproc that use unequal angles of small rotation. These newer systems utilize M-wire alloy and are designed for maximum flexibility and fatigue resistance. Studies show reciprocating systems take less time than rotary systems while maintaining canal anatomy, though results on debris removal are mixed and they may cause more dentinal defects.
Reciprocating instruments in endodontics
- 2. History of development of reciprocating system • The greatest No. of commercially available files utilized to shape root canals are manufactured from NiTi and are mechanically driven in continuous rotation. • On the other hand, reciprocation, defined as any repetitive back-and-forth motion, has been clinically utilized to drive stainless steel files since 1958. • Initially, all reciprocating motors and related handpieces rotated files in large equal angles of 90º clockwise (CW) and counterclockwise (CCW) rotation.
- 3. • Over time, virtually all reciprocating systems in the marketplace began to utilize smaller, yet equal, angles of CW/CCW rotation. The M4, Endo-Eze, and Endo-Express are examples of reciprocating systems that utilize small, equal 30º angles of CW/CCW rotation. Further, these systems have recognized limitations, including decreased cutting efficiency, more required inward pressure, and a limited capacity to auger debris out of a canal. • In about 1998, Dr. Ben Johnson and Professor Pierre Machtou co-discovered the unmistakable advantages of reciprocating NiTi files utilizing unequal bidirectional movements. • After that, Machtou and his endodontic residents extensively analyzed this novel unequal reciprocating movement using the entire series of not-yet-to market PT files.
- 4. • Dr. Ghassan Yared, a former student of Professor Machtou, performed exhaustive work to identify the precise unequal CW/CCW angles that would enable a single reciprocating 25/.08 PT file to optimally shape virtually any canal. • In 2008, a team of 8 international clinicians including Drs. Ben Johnson, Sergio Kuttler, Pierre Machtou, Wilhelm Pertot, Julian Webber, John West, Ghassan Yared, and Ruddle, in collaboration with Dentsply International, began the serious work of developing both a new reciprocating file and motor for shaping canals. • In 2011, following 4 years of research and development, both WaveOne (Dentsply Tulsa Dental Specialties and Dentsply Maillefer) and RECIPROC (VDW) were internationally launched as single-file shaping techniques.
- 5. Rotation and Reciprocation • Compared to reciprocation, continuous rotation utilizing well- designed active NiTi files requires less inward pressure and improves hauling capacity auguring debris out of a canal. • On the other hand, a mechanical reciprocating movement has merit because it somewhat mimics manual movement and reduces the various risks associated with continuously rotating a file through canal curvatures. • Reciprocation of Ni-Ti instruments have the following advantages over continuous rotation: 1. Binding of the instruments into the root canal dentine walls is less frequent, reducing torsional stress. 2. The reduction of the number of cycles within the root canal during preparation results in less flexural stress on the instrument. 3. There is decreased risk of instrument fracture.
- 6. • RECIPROC file and WaveOne file are able to completely prepare root canals with only one instrument. • These files are made of a special nickel–titanium alloy called M-wire that is created by an innovative thermal treatment process. The benefits of this M-wire alloy are increased flexibility and improved resistance to cyclic fatigue of the instruments. • The RECIPROC and WaveOne files are used in a reciprocal motion that requires special automated device (motor). • These files are single use to avoid stress and wear on the active portion of the files and to prevent potential for cross- contamination between and among patients. Reciprocating files
- 7. WaveOne file system • It is a new single-instrument mechanized shaping system (DENTSPLY Maillefer, Ballaigues, Switzerland). In most instances, the WaveOne concept provides a single file shaping technique, regardless of the length, diameter, or curvature of any given canal. • In fact, it has been shown that a single file reciprocating shaping technique utilizing unequal CW/CCW angles is over 4 times safer and almost 3 times faster than using multiple rotary files to achieve the same final shape.
- 8. • Strategically, only 1 file is generally utilized to fully shape virtually any given canal. However, there are 3 WaveOne files available to effectively address a wide range of endodontic anatomy commonly encountered in everyday practice. 1. WaveOne Small file: is used in fine canals. The tip size is ISO 21 with a continuous taper of 6%. 2. WaveOne Primary file: is used in the majority of canals. The tip size is ISO 25 with an apical taper of 8% that reduces towards the coronal end. 3. WaveOne Large file: is used in large canals. The tip size is ISO 40 with an apical taper of 8% that reduces towards the coronal end.
- 9. Design features of WaveOne files system • The WaveOne files have changing pitch and helical angle along their active portions, and 2 distinct cross-sections along the length of their active portions. From D1-D8, the WaveOne files have a modified convex triangular cross-section, whereas from D9-D16, these files have a convex triangular cross-section. • The WaveOne files have noncutting modified guiding tips which enable these files to safely progress through virtually any secured canal. • Together, these design features enhance safety and efficiency when shaping canals that have a confirmed, smooth, and reproducible glide path.
- 10. Reciprocation movement & WaveOne motor • The e3 motors (Dentsply Tulsa Dental Specialties) is specially engineered and programmed to drive the new WaveOne reciprocating files. The WaveOne motor is rechargeable battery operated with a 6:1 reducing handpiece. • This motor produces a feature-specific, unequal bidirectional file movement. Because of the reverse helix design, the CCW engaging angle is 5 times the CW disengaging angle. Additionally, it should be noted, this motor can drive any market version file system in full CW rotation at the desired speed and torque.
- 11. File selection • If a # 10 K-file is very resistant to movement, use WaveOne Small file. • If a # 10 K-file moves to length easily, is loose or very loose, use WaveOne Primary file. • If a # 20 K-file or larger goes to length, use WaveOne Large file.
- 12. Clinical guidelines for the use of WaveOne file • Create straight line access. • Negotiate canals to patency and create a reproducible glide path. • Select the correct WaveOne file. • Clean the cutting flutes of the instrument after each cutting cycle. • Irrigate and recapitulate the root canal system after each cutting cycle, and lubricated canal before using file. • Faster preparation time requires longer irrigation times preferably with activation of irrigation solution. Because of the reduced preparation time, the tissue in uninstrumented parts of the root canal system have generally been exposed for a shorter period of time to the irrigation solution of choice.
- 13. • A WaveOne file was used in a reciprocating motion according to the manufacturer’s instructions using (WaveOneTM endo motor). The silicon stopper was set on the WaveOne file at 2/3 of WL. • Then, the file was introduced in the canal with a slow in (light apical directed force) and out (circumferential brushing) motion without pulling the instrument completely out of canal. • After 3 in-and-out movements, the WaveOne file was pulled out of the canal to clean the flutes, and the canal was irrigated. • The WaveOne file was used until it had reached 2/3 of the WL as indicated by stopper on the file. Then the file was reused in the same manner until the WL had been reached. Shaping technique of WaveOne
- 14. RECIPROC file system • It is a new system for single file reciprocation without prior use of hand files. It was developed as single-file shaping techniques (VDW). • The system includes three instruments (R25, R40 and R50) Only one RECIPROC instrument is used for the canal preparation depending on the initial size of the canal. The three instruments have regressive taper, which are: 1. R25 has a diameter of 0.25mm at the tip and an 8% taper over the first 3mm from the tip. The diameter at D16 is 1.05mm. 2. R40 has a diameter of 0.40mm at the tip and a 6% taper over the first 3mm from the tip. The diameter at D16 is 1.10mm. 3. R50 has a diameter of 0.50mm at the tip and a 5% taper over the first 3mm from the tip. The diameter at D16 is 1.17mm.
- 15. Design features of RECIPROC file system • These instruments are made from an M-wire NiTi. The three instruments have non-cutting tips. They have an S shaped cross- section.
- 16. • VDW. SILVERS® RECIPROC® is battery operated motor used with RECIPROC system. The battery is rechargeable and the motor can be used while the battery is charging. • There are preprogrammed settings for reciprocating system The instruments are used at 10 cycles of reciprocation per second. Reciprocation movement & RECIPROC motor • When the instrument rotates in the cutting direction it will advance in the canal and engage dentine to cut it. When it rotates in the opposite direction (smaller rotation) the instrument will be immediately disengaged.
- 17. File selection
- 18. Shaping technique of RECIPROC file Clinical guidelines for the use of RECIPROC file • Same as in WaveOne file
- 19. Studies on reciprocating instruments • The reciprocating movement induced less cyclic fatigue and promoted an extended life of the ProTaper F2 instruments in comparison with conventional rotation. • RECIPROC instruments were associated with a significantly higher cyclic fatigue resistance than the WaveOne instruments. • The authors speculated that this could be attributed to the possible difference in the cross-sectional designs of the two instruments. 1. Cyclic fatigue
- 20. • The use of Reciproc and WaveOne instruments resulted in less debris removal compared with canal shaping performed with ProTaper instruments. • The studies showed that pecking motion could lead to debris compaction while a brushing motion leads to debris removal. 3. Debris extrusion 2. Debris removal • Filing with Reciproc showed more apical debris extrusion compared with that seen withWaveOne and also with rotation ProTaper. • A probable explanation for this finding is that rotary motion tends to pull dentinal debris into the flutes of the file and directs it toward the coronal aspect of the canal. Also, continuous rotation compared to reciprocation, requires less inward pressure and improves capacity to auger the debris out of a canal. • Many researchers found that instrumentation techniques produce some debris extrusion and this can induce inflammation within the periapical area; therefore, instrumentation technique that causes less extrusion of debris is more desirable.
- 21. • The presence of bacteria is the main cause of the development of periodontal infection and apical periodontitis. The aim of chemomechanical root canal preparation is to eradicate residual vital and non-vital pulp tissue and reduce the number of pathogenic organisms. Mechanical instrumentation can disrupt the bacterial biofilm and has the potential to reduce the presence of bacteria in the main root canal. • Reciprocating systems resulted in similar bacterial reductions to those obtained with rotary systems or with the manual instrumentation technique. 4. Bacterial reduction
- 22. 5. Maintenance of root canal anatomy • Reciproc and WaveOne instruments were found to maintain the original canal contour. • In curved canals, Its better instrumented with reciprocating files than with rotary, which tend to transport the outer canal wall of the curve in the apical part of the canal. • Reciprocating systems showed good ability and suitable for shaping curved canals with only one instrument.
- 23. • A recent study compared the incidence of dentinal defects after root canal preparation with reciprocating (WaveOne 40/08 and Reciproc R40) and with rotary instrumentation (Mtwo and Pro- Taper Universal) on extracted human central lower incisors: The study concluded that all four systems caused dentinal defects, but both reciprocating systems caused significantly more incomplete cracks in the apical (3mm) portion of the root canals. RECIPROC was associated with more complete cracks compared with the full sequence rotary systems. 6. Dentinal defects/cracks
- 24. • Reciprocating files were faster than rotating files. • The primary WaveOne files were significantly faster for canal preparation compared to the Reciproc R25 files. • According to the authors with the study the difference can be attributed to the fact that WaveOne instruments have three cutting blades and might have better cutting efficacy than the two-bladed Reciproc properties of the instruments. 7. Clinical efficiency 8. Centric ability • WaveOne and Reciproc instruments obtained better centering ability at all levels especially at the end point of preparation comparing with Protaper and Mtwo instruments.
- 25. • The clinical technique in which reciprocating instruments like WaveOne and RECIPROC are used can play a vital role in the successful outcome of the cleaning and preparation phase of endodontic treatment. Most studies agree that the reciprocating movement can reduce torsional (binding to dentine is reduced) and flexural stresses (number of rotation cycles are reduced) on endodontic instruments. • These instruments, also maintain the original canal anatomy and demonstrate reduced time for canal preparation compared with full rotary systems. • However, there are conflicting results in the literature regarding the efficacy of debris removal and bacterial reduction and there remains the possibility of debris extrusion and dentinal crack formation during root canal preparation with reciprocating instruments. Conclusions