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.

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